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Dixit, Sameer M. "Antagonistic activity of probiotic bacteria based on bacterial diversity in the porcine gut." View thesis, 2004. http://handle.uws.edu.au:8081/1959.7/35614.
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Thesis (Ph.D.)--University of Western Sydney, Hawkesbury, 2004.A thesis presented to the University of Western Sydney, Hawkesbury, Centre for Advanced Food Research, in fulfilment of the requirements for the degree of Doctor of Philosophy. Includes bibliographies.
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Revetta, Randy P. "Isolation and identification of freshwater bacteria antagonistic to Giardia Intestinalis." Cincinnati, Ohio : University of Cincinnati, 2006. http://www.ohiolink.edu/etd/view.cgi?acc%5Fnum=ucin1141305893.
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Thesis (M.S.)--University of Cincinnati, 2006.Title from electronic thesis title page (viewed Apr. 13, 2006). Includes abstract. Keywords: Giardia intestinalis; Cytophaga-Flavobacterium; Cyst degradation; Microbial antagonism. Includes bibliographical references.
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Tydings, Heather Anne. "Identification and Optimization of the Antagonistic Potential of Native Spinach Microbiota towards Escherichia coli O157:H7." Thesis, Virginia Tech, 2010. http://hdl.handle.net/10919/43364.
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Leafy greens such as spinach have been the object of several recent food-borne pathogen outbreaks. The purpose of this study was to isolate bacteria spinach epiphytic bacteria that inhibit growth of E. coli O157:H7, which we describe as antagonism. The mechanism of antagonism was investigated and we attempted to improve the antagonistic potential in vitro and on spinach leaves when cellobiose, a carbon source utilized by the antagonists but not E. coli O157:H7, was added.
There were larger culturable populations of bacteria on the leaves of savoyed cultivars compared to flat. From the isolated colonies, 47 displayed antagonism towards E.coli O157:H7, and were identified as members of 11 different genera and sixteen species. A representative isolate from each species was evaluated for three possible mechanisms of antagonism: acid production, secretion of an inhibitory compounds or secreted protease. The majority (14/16) produced at least a moderate level of acid. Two of these strains, Paenibacillus polymyxa and Pseudomonas espejiana, were found to secrete a non- protease antagonistic compound.
These antagonists varied in their reduction of E.coli O157:H7 numbers in vitro, but all significantly reduced numbers in 48 hours of co-culturing in nutrient rich media. Five antagonists resulted in a significant reduction in E.coli O157:H7 populations when co-cultured on spinach leaves. Application of cellobiose did not improve the amount of antagonism in vitro or on the leaf surface after 24 hours.Master of Science
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REVETTA, RANDY PRIMO. "ISOLATION AND IDENTIFICATION OF FRESHWATER BACTERIA ANTAGONISTIC TO GIARDIA INTESTINALIS." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1141305893.
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Saijonma-Koulumies, Leena E. M. "Bacterial interference in the control of canine pyoderma." Thesis, Royal Veterinary College (University of London), 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368117.
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Mahdy, Magdy. "Biological control of plant parasitic nematodes with antagonistic bacteria on different host plants." Bonn : Rheinische Friedrick-Wilhelms-Universität, Institut für Pflanzenkrankheiten, 2002. http://hss.ulb.uni-bonn.de/ulb_bonn/diss_online/landw_fak/2002/mahdy_magdy/0203.pdf.
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Kumar, Pratheesh [Verfasser]. "Study on Antagonistic and Growth Promotion Potential of Certain Exo and Endophytic Bacteria of Mulberry (Morus SPP.) : Biological control / Pratheesh Kumar." München : GRIN Verlag, 2019. http://d-nb.info/118869961X/34.
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Chidburee, Siripun. "Biological control of soil-borne disease in soybean by denitrifying antagonistic bacteria : the possible role of reduced nitrogen compounds for control of plant pathogens." Thesis, University of Aberdeen, 1998. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU602299.
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A number of experiments were carried out to study the potential of denitrifying bacteria and reduced nitrogen compounds for control of soil-borne damping-off pathogens. Measurement of the rhizosphere pH of growing soybean roots was carried out in soil adjusted to different pH states and packed into sheet microcosms. The results showed that the rhizosphere pH of soybean was lower than the bulk soil. Nitrate reductase activity and nitrite production was then characterised for the rhizosphere of intact 14 day-old soybean roots that were incubated in nitrate substrates adjusted to different pH values under water-logged conditions. The results showed that the rate and the quantity of nitrite production increased with increasing nitrate concentration and pH in the solution. A growth room experiment was carried out to determine root colonization by denitrifying bacteria in relation to disease caused by soil-borne pathogens, which are favoured by high soil moisture (approximately -5 KPa) and low oxygen levels. Nitrite producing bacteria were isolated from soybean roots grown in Grampian (Insch) soils which had not been cropped with soybean and Thai (Phitsanulok) soils which previously had been cropped with soybean. In the first pot experiment, the nitrite producing bacteria were isolated from different root sections of 12 and 19 day-old soybean plants after 8 weeks of continuous cropping of soils with soybean (a new crop was planted every week), and using different isolation media in order to determine the genus/species composition of the denitrifying bacteria on the rhizoplane. The results showed that continuous cropping of Thai soil and Insch soil with soybean increased pre-emergence damping-off disease and decreased fresh weight yields in seedlings that did emerge. ANOVA showed significant differences between root sections for most bacterial groups monitored {Bacillus spp., Pseudomonas and Enterobacteriaceae), with regression analysis generally showing densities increasing with root age or toward the shoot base. All nitrite producing bacterial isolates were screened for antifungal activity against Macrophomina phaseolina on agar plates and between 10 and 25% of nitrite producing bacteria were found to show in vitro antagonism. In a second pot experiment, the nitrite producing bacteria were isolated from root tissue below the crown (5 cm in length) every 2 weeks of continuous cropping of soils with soybean (a new crop was planted every 2 weeks). Plate-counting was carried out to determine the population of nitrite producing bacteria while a liquid culture MPN method was used for determination of NO, N2O and N2 producing bacteria. Linear regression analysis of the incidence of pre-emergence damping-off and soybean yields in seedling that did emerge showed a highly significant negative correlation between these parameters for both soils. ANOVA showed that there was a significant difference between soil type, with the Thai soil showing higher population densities of antagonistic bacteria on soybean roots. All nitrite producing bacterial isolates were screened for antifungal activity, but the plant pathogenic fungus, Pythium ultimum, was used in this experiment. The results showed that between 10 and 40% of nitrite producing bacteria showed in vitro antagonism. However, regression analysis showed that there was no significant increase or decrease in the nitrite producing antagonistic bacterial population with continuous soybean cropping. All 900 isolates of nitrite producing bacteria isolated from the soybean rhizoplane were screened for antagonistic activity towards Pythium ultimum based on a pot trial assay in the greenhouse. As expected, very low numbers of nitrite producing bacteria showed activity against P. ultimum and only one isolate gave a significant reduction in disease incidence in pot trials. The interactive effects of nitrite producing antagonist and an Arbuscular Mycorrhizal fungus (Glomus mosseae) and Bradryrhizobium japonicum, on control of the fungal pathogens, P. ultimum or M. phaseolina were investigated in the greenhouse. The results showed that improved plant growth was obtained with certain combined inocula involving nitrite producing bacterial antagonists, Glomus mosseae and Bradryrhizobium japonicum.
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Souza, Ariane do Carmo. "Controle biológico de Alternaria alternata, agente causal da mancha marrom de alternaria, por Bacillus SPP." Universidade Federal de São Carlos, 2018. https://repositorio.ufscar.br/handle/ufscar/10473.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
The alternaria brown spot, caused by Alternaria alternata f sp. citri, causes large economic damages in tangor Murcott (Citrus sinensis Osbeck x Citrus reticulata [L.] Blanco). Its control is carried out through the spraying of agrochemicals, implying up to 15 pulverizations per year, which causes an increase in the production costs of the cultures and damages to the environment. As an alternative, the use of microorganisms, in particular Bacillus spp., has been used to diseases’ control. Therefore, the aim of this work was to evaluate the viability of Bacillus spp in in vitro and in vivo conditions. The methodologies were based on the interactions between biological control agents (Bacillus spp.) and the phytopathogen A. alternata, evaluated by the paired culture technique, by the production of volatile, thermostable and cell-free metabolites by different Bacillus spp. isolates. The molecular identification of the isolates tested and the efficacy of bacterial isolates were evaluated in leaves and plants under greenhouse conditions. The results showed that most of the isolates affected the development of phytopathogen and produced some types of metabolite, being antibiosis one of the probable mechanisms of action of the bacterium. The isolates ACB-01, ACB-07, ACB-08, ACB-18 and ACB-57 presented potential for disease control of A. alternata.
A mancha marrom de alternaria, causada por Alternaria alternata f sp. citri, causa grandes danos econômicos em tangor Murcott (Citrus sinensis L. Osbeck x Citrus reticulata [L.] Blanco). Seu controle é realizado através de pulverizações com agroquímicos, implicando em até 15 pulverizações por ano, o que acarreta em aumento no custo de produção da cultura e prejuízos ao meio ambiente. Como alternativa, o uso de microrganismos, em particular, as bactérias do gênero Bacillus spp., têm sido empregadas para o controle de doenças. Portanto, esse trabalho teve por objetivo avaliar em condições in vitro e in vivo a viabilidade de 47 isolados de Bacillus spp. para o controle da doença. As metodologias foram embasadas nas interações entre agentes de controle biológico (Bacillus spp.) e o fitopatógeno A. alternata avaliadas pela técnica de cultivo pareado, pela produção de metabólitos voláteis, termoestáveis e livre de células por diferentes isolados de Bacillus spp.. Realizou-se, ainda, a identificação molecular dos isolados testados e a eficácia dos isolados da bactéria em folhas destacadas e em plantas, sob condições de casa de vegetação. Os resultados obtidos mostraram que a maioria dos isolados afetou o desenvolvimento do fitopatógeno e produziram algum tipo de metabólito, sendo, a antibiose um dos prováveis mecanismos de ação da bactéria. Os isolados ACB-01, ACB-07, ACB-08, ACB-18 e ACB-57 apresentaram potencial para o biocontrole de A. alternata.
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Goh, Wai Kean Chemistry Faculty of Science UNSW. "Novel antagonists of bacterial signaling pathways." Publisher:University of New South Wales. Chemistry, 2008. http://handle.unsw.edu.au/1959.4/41458.
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Traditional bacterial disease therapies utilize compounds that ultimately kill the target bacteria but it exerts a strong selective pressure on the bacteria to develop multi-drug resistance mutants. The increasing occurrence of resistance in common pathogens has highlighted the need to identify new anti-microbials that target the control of bacterial pathogenicity in a non-extermination manner to reduce the incidence of bacteria resistance. One new strategy exploits the discrete signaling molecules that regulate the various bacterial signaling pathways, which are responsible for the expression of pathogenicity traits. Halogenated furanones (fimbrolides) from the marine red alga, Delisea pulchra have been shown to interfere with the key signaling pathway present in Gram-negative bacteria by competitively displacing the cognate signaling molecule from the transcription protein. This project focused on the design and synthesis of 1,5-dihydropyrrol-2-ones, a new class of fimbrolide derivatives capable of displaying strong antagonistic properties of the fimbrolides. Primary synthetic methodologies examined include the halolactamization of allenamides and the direct lactone-lactam transformation. No doubt, both methodologies yielded the lactam ring, the former failed to introduce the crucial C-5 bromomethylene group essential for bioactivity. A facile high yielding two-step lactone-lactam transformation method was developed and using this method, a wide range of substituted 5-bromomethyl- and 5-dibromomethylene-1,5-dihydropyrrol-2-ones were synthesized. Furthermore, a new class of tricyclic crown-ether type compounds with no literature precedent were discovered. To vary the diversity of the compounds, a related class of compounds, 5,6-dihydroindol-2-ones, were examined. A general versatile method for the synthesis of 7-substituted 5,6-dihydroindol-2-ones was developed. The synthetic strategy proceeds via the established Suzuki-Miyaura cross-coupling reaction of halogenated dihydroindol-2-ones with arylboronic acids/esters. The Suzuki methodology was found to be reliable in furnishing a wide range of 7-substituted products in high yields. A preliminary molecular modeling approach was used to assist in the design of new anti-microbials via the ligand-docking analyses of the TraR and LasR protein. A positive correlation was observed between the docking scores and biological activity and the methodology was further developed into an initial screening tool to filter potential active and non-active compounds. The newly synthesized compounds were analysed for their efficacy in reducing the expression of the Green Fluorescent Protein (GFP) in the presence of natural AHL signaling molecules in an AHL-monitor strain, indicative of the inhibition of bacterial phenotype expression. The dihydropyrrol-2-one class of compounds showed significant biological activity and this highlighted their potential for further development.
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Perez, Fernanda dos Santos Arthuso. "Influência da temperatura de cultivo na expressão de proteínas recombinantes de interesse terapêutico no espaço periplásmico bacteriano, utilizando o promotor lambda PL." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/85/85131/tde-19102015-150711/.
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O sistema de expressão baseado nos promotores PL ou PR do fago lambda que usualmente é regulado pelo repressor termo lábil (cIts) é amplamente utilizado para produzir proteínas recombinantes em células procarióticas. No entanto, o aumento da temperatura requerido neste sistema para promover a inativação do repressor apresenta algumas limitações, como o aumento da expressão de proteínas de HSP (Heat Shock Proteins), por exemplo, proteases, que dependendo da natureza da proteína expressa podem ser prejudiciais ou não. Uma outra limitação é a ativação da resposta SOS, resultando na parada da replicação do DNA celular ou dependendo da cepa pode ocorrer lise celular. Nesse trabalho nós descrevemos o uso do promotor λPL para expressão constitutiva, isto é, sem a regulação do repressor. Nós otimizamos diferentes condições de cultura para aumentar a secreção no espaço periplásmico de Escherichia coli de cinco proteínas: o hormônio do crescimento humano (hGH), que tem sido amplamente utilizado no tratamento de crianças com deficiência e/ou resistência ao hGH, síndrome de Turner, entre outras desordens; prolactina humana (hPRL), um hormônio polipeptídico conhecido por estimular a lactação e por exercer ação regulatória no crescimento e na diferenciação da glândula mamária, dois antagonistas de hPRL, estudados como potenciais fármacos para o tratamento de alguns tipos de cânceres e por fim o interferon α2a (IFN-α2a), que é uma citocina produzida pelas células, em resposta a diferentes estímulos, incluindo ácidos nucléicos virais, células estranhas (particularmente as neoplásicas), antígenos de bactérias, protozoários e vírus. No caso do IFN-α2a, essa citocina de alto valor agregado e de importante aplicação terapêutica, foi desenvolvida em nosso laboratório como parte desse trabalho, incluindo o desenvolvimento e a validação da metodologia de análise por HPLC de fase reversa para determinação do IFN presente no fluído periplásmico bacteriano ou na sua forma pura. As principais estratégias utilizadas para melhorar a expressão foram iniciar a indução junto à densidade óptica máxima do crescimento bacteriano e otimizar a temperatura de indução para controlar a expressão da proteína heteróloga. Essa metodologia pode ser utilizada nos casos onde o produto não será tóxico para a célula hospedeira ou quando a instabilidade do plasmídeo não é problema. A possibilidade de cultivo em temperaturas mais baixas, já que o repressor termo-sensível não se encontra presente, colaborou para o aumento significativo da expressão, mesmo para proteínas menos sensíveis à temperatura de cultivo, como o hGH.The expression system based on the PL or PR promoters of the lambda phage that is usually regulated by the term labile repressor (clts) is widely used to produce recombinant proteins in prokaryotic cells. However, the temperature increase required in this system to promote the repressor inactivation shows some limitations, like the increase of the HSP (Heat Shock Proteins) proteins expression, proteases e.g., that depending on the nature of the expressed protein can be harmful or not. Another limitation is the activation of SOS response, resulting on the stop of the DNA cell replication or depending on the strain can occur cell lysis. In this paper we describe the use of the λPL promoter for constitutive expression, without the repressor regulation. We optimized different cultivation conditions to increase the secretion in the periplasmic space of Escherichia coli of five proteins: the human growth hormone (hGH), that is being widely used in the treatment of children with disabilities and/or resistance to hGH, Turner syndrome, within another disorders; human prolactin (hPRL), a polypeptide hormone known for stimulating the lactation and for exercising regulatory action on growth and on the differentiation of the mammary gland; two hPRL antagonists, studied as potential medicine to the treatment of some kinds of cancers and finally the interferon α2a (IFN-α2a), that is a cytokine produced by the cells, in response to different actions, including viral nucleic acids, neoplastic cells, antigens of bacteria, protozoa and viruses. In the case of IFN-α2a, this high value added and important therapeutic application, was developed in our laboratory as a part of this paper, including the development and the validation of the analysis methodology by reversed-phase HPLC to determine the IFN present in the bacterial periplasmic fluid or in its pure form. The main strategies used to improve the expression were to start the induction with the maximum optical density of bacterial growth and optimize the induction temperature to control the expression of heterologous protein. This methodology can be used in cases where the product wont be toxic to the host cell or when the instability of the plasmid is not a problem. The possibility of cultivation in lower temperatures, since the heat-sensitive repressor is not present, contributed to the significant increase of the expression, even to proteins that are less sensitive to the cultivation temperature, like the hGH.
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Zamora, Rodríguez Lucero M. "Aislamiento, identificación y conservación de cultivos de bacterias lácticas antagonistas de microbiota contaminante de sangre de matadero." Doctoral thesis, Universitat de Girona, 2003. http://hdl.handle.net/10803/7925.
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La sangre obtenida en el matadero es un producto altamente contaminado que requiere un procesamiento inmediato si se pretende utilizarla como insumo alimentario en la fabricación de productos destinados al consumo humano. Si bien es cierto que los sistemas de higienización podrían ser muy eficientes desde el punto de vista de calidad microbiológica, su instalación en la línea de sacrificio comportaría muchas dificultades desde el punto de vista técnico y en algún caso sería muy costoso. La bioconservación podría ser una alternativa para mejorar la calidad microbiológica de la sangre, alargar su vida útil y reducir las posibilidades de procesamiento inmediato. El presente estudio nos permitiría formular la posibilidad de aplicar la bioconservación en sangre de cerdo procedente de matadero industrial, utilizando bacterias ácido lácticas (BAL) como cultivo bioprotector, para lo cual se aislaron cepas de BAL autóctonas y se confeccionaron dos colecciones una de BAL mesófilas y otra de psicrótrofas.
Se evaluó el potencial antagonista de la colección de BAL mesófilas y psicrótrofas a 30ºC y a 15ºC respectivamente frente a bacterias contaminantes habituales de este subproducto. Las BAL que demostraron antagonismo en placa (7,1% a 30ºC y 11% a 15ºC) fueron seleccionadas para evaluar el potencial antagonista en sangre, donde el efecto inhibitorio se vio favorecido por la adición de un 2% glucosa. S.aureus y P. fluorescens fueron los indicadores más inhibidos por las cepas mesófilas, en algunos casos con reducciones superiores a 7 unidades logarítmicas. En condiciones psicrótrofas la bacteria más sensible a la presencia de BAL fue Bacillus sp., donde 8 de las 11 BAL ensayadas permitieron reducciones superiores a 4 logs y 1cepa incluso superiores a 7 logs; se obtuvieron reducciones máximas de 3 logs de E.coli y Pseudomonas fue inhibida por todas las BAL ensayadas, en algún caso con reducciones superiores a 5 logs.
Las 5 que cepas que presentaron el espectro de inhibición más amplio en condiciones mesófilas y 7 en condiciones psicrótrofas frente a los microorganismos indicadores contaminantes de sangre de matadero se identificaron mediante técnicas moleculares por comparación de la secuencias correspondientes al gen que codifica la síntesis de 16S ARNr (16S ADNr) con las secuencias publicadas en las bases de datos.
De las 7 cepas antagonistas en condiciones psicrótrofas 5 se identificaron como Lactococcus garvieae y 2 como Enterococcus malodoratus/gilvius raffinosus. Todas las BAL con potencial antagonista en condiciones mesófilas pertenecían al género Lactobacillus, 3 de elllas se identificaron como Lactobacillus murinus/animalis y una se identificó como Lactobacillus reuteri. TA20 que tuvo un gran espectro de inhibición a ambas temperaturas se identificó como Lactococcus garvieae.
En este estudio se evaluaron tres métodos de conservación a largo plazo de las cepas que mostraron potencial antagonista. Se comparó la liofilización, la atomización frente a la congelación a -80ºC que era método que se había utilizado hasta el momento para conservar ambas colecciones de BAL. En general, los métodos de deshidratación (atomización y liofilización) y mantenimiento en refrigeración a 5ºC de los cultivos deshidratados se han mostrado más eficaces que la congelación.
Blood from slaughtered animals is a product with a high contamination level that requires an immediately processing after collection if the object is to use it as a food ingredient destined to human consumption. Nevertheless, even if hygienic collection systems used in abattoirs were be efficient enough to control the microbiological quality, their installation in the slaughtered line would be technically complicate and in some case would be so expensive.
Bioconservation is an alternative to improve microbiological quality, to extend its shelf life and reducing the possibility of immediate processing after collection.
The present study would permit us to formulate the possibility to applicate bioconservation in porcine blood from industrial abattoirs, using lactic acid bacteria (LAB) strains as biopreservative cultures. So a mesophylic and a psicrotrophyc LAB strains collections were confectioned.
The antagonistic capacity toward usual contaminant bacteria in blood of the mesophylic and psicrotrophyc collections at 30ºC and 15ºC respectively were investigated. The LAB that demonstrated the widest inhibitory spectrum in agar plate evaluation (7,1% at 30ºC and 11% at 15ºC) were screened in order to evaluate their inhibitory activity in blood, where was observed that the addition of glucose at 2% had a positive effect in the inhibitory levels.
The most sensible indicators to the mesophylic LAB were S. aureus and P. fluorescens. In some cases it was obtained reductions of 7 logarithmic units. In psicotrophic conditions the most sensible bacteria to LAB presence was Bacillus spp. where 8 of the 11 strains assayed inhibited in more than 4 logarithmic units and 1 of them inhibited this indicator in 7 logarithmic units..
It was obtained maxim reductions of 3 logs versus E. coli. P. fluorescens was inhibited by all the assayed strains and in some case it was obtained reductions superior to 5 logs.
The 5 mesophylic and 7 psictrophyc strains that demonstrated the widest inhibitory spectrum toward the indicators microorganisms from abattoir blood were identified using molecular techniques though comparison of the gene sequences that codify the synthesis of 16S RNAr (16S DNAr) with the sequences in the data base.
5 from the 7 strains with antagonistic capacity in psicotrophyc conditions were identified like Lactococcus garvieae and the other two strains were identified like Enterococcus malodoratus/gilvius/raffinosus. All the antagonistic LAB in mesophylic conditions belonged to genus Lactobacillus, 3 of them were identified like Lactobacillus murinus/animalis and one of them as Lactobacillus reuteri. TA20 that had a widest spectrum at both assay temperatures was identified as Lactococcus garvieae.
In this study there were evaluated three methods of conservation of cultures belonged to those LAB that demonstrated antagonistic capacity. It was compared freeze-drying, spray drying against freezing at -80ºC, that is the method used to conserve both LAB collections. Generally, the dehydration methods (freeze-drying and spray drying) and maintaining in refrigeration at 5ºC of dehydrated cultures showed to be better than freezing at -80ºC.
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Gomes, Fernanda Sgarbosa. "Antagonismo entre leveduras e bactérias láticas na fermentação alcoólica." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/11/11141/tde-23022010-092650/.
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Com o objetivo de avaliar o antagonismo entre leveduras e bactérias contaminantes do processo de produção de etanol com metabolismos distintos (homo e heterofermentativo) em diferentes condições, foi analisado o desempenho fermentativo de linhagens de Saccharomyces cerevisiae empregadas na fermentação industrial (BG- 1, CAT-1, PE-2 e Fleischmann) em co-cultivo com linhagens de Lactobacillus com diferentes metabolismos, sendo uma delas homofermentativa (L. plantarum - FT025B) e duas linhagens heterofermentativas (L. fermentum - FT230B e L. fructosus - FT432B). Foram avaliados o crescimento dos dois grupos de microrganismos com relação à densidade de células no meio e sua viabilidade e também através de suas atividades metabólicas, acessadas pela formação de metabólitos específicos (ácidos lático, succínico e acético, manitol e etanol). Os experimentos foram conduzidos em duas modalidades: I) em condições de laboratório, inoculando-se uma linhagem bacteriana com uma única linhagem de levedura na mesma proporção em meio sintético e sendo incubadas a 32 C por 24h e II) simulando as condições industriais de fermentação, com alimentação utilizando-se mosto misto durante 5 reciclos fermentativos. No Experimento I, a viabilidade da linhagem FT025B mostrou-se reduzida em relação à linhagem FT230. Observou-se também que no meio contendo a bactéria FT025B a viabilidade das 4 linhagens de levedura foi menor do que no meio controle e no meio inoculado com a bactéria FT230B. Os níveis de ácido lático foram mais elevados na presença da bactéria FT025B, enquanto os teores de ácido acético e de glicerol foram maiores nos meios com a linhagem FT230B. A produção de etanol foi reduzida na presença de ambas as bactérias. No Experimento II a presença das bactérias praticamente não afetou a viabilidade das leveduras industriais durante os reciclos. No entanto, ao contrário do que foi observado no Experimento I, as linhagens bacterianas heterofermentativas apresentaram melhor crescimento e maior viabilidade em co-cultivo com as leveduras do que a homofermentativa. Também na presença de ambas as linhagens heterofermentativas observou-se uma significativa redução no rendimento alcoólico. A produção de lactato por tais linhagens foi muito próxima e em alguns ciclos até maior que a produção pela linhagem homofermentativa. No entanto, como no Experimento I, nos tratamentos com a bactéria FT025B a produção de glicerol foi menor até mesmo que no tratamento controle, tratando-se do primeiro registro de menor produção de glicerol por leveduras que se encontram na presença de contaminação bacteriana. Sugere-se que o ácido lático e o acético, juntamente com o etanol, podem ter agido sinergisticamente no metabolismo e crescimento das leveduras, resultando principalmente em uma diminuição do rendimento alcoólico. É também provável que as linhagens bacterianas heterofermentativas foram capazes de resistir melhor aos elevados teores de etanol excretados pelas leveduras e encontrados no processo industrial, uma vez que também são capazes de produzir tal composto.This study aimed to evaluate the antagonism between yeasts and contaminating bacteria of the ethanol production process with different metabolisms (homo- and heterofermentative) in different conditions. Thus, the fermentation performance of Saccharomyces cerevisiae strains used in industrial fermentation (BG-1, CAT-1, PE-2 and Fleischmann) was analyzed in co-cultivation with Lactobacillus strains with different metabolisms, one of them homofermentative (L . plantarum - FT025B) and two heterofermentatives strains (L. fermentum - FT230B and L. fructosus - FT432B). It was evaluated the growth of two microrganisms groups with respect to the cells density in the medium and their viability and also through their metabolic activities, accessed by specific metabolites production (lactic, acetic and succinic acid, mannitol and ethanol). The experiments were conducted in two ways: I) in laboratory conditions, inoculating a bacterial strain with a single yeast strain in the same synthetic medium incubated at 32°C for 24h and II) simulating the industrial fermentation conditions, with fed by using mixed must for 5 fermentative recycle. In Experiment I, the viability of FT025B strain proved to be small in relation to FT230 strain. It was also observed that in the medium containing the bacteria FT025B the viability of the 4 yeast strains was lower than the control and the treatment with FT230B strain. The levels of lactic acid were higher in the presence of bacteria FT025B, while the levels of acetic acid and glycerol were higher in treatments with FT230B strain. The production of ethanol was reduced in the presence of both bacteria. In Experiment II, the presence of bacteria did not affect the viability of industrial yeasts during recycling. However, contrary to what was observed in Experiment I, the heterofermentatives bacterial strains showed higher growth and higher viability in co-cultivation with the yeasts than homofermentative. Also in the presence of both strains heterofermentatives there was a significant reduction in the alcoholic yield. The lactate production by these strains was very close and, in some cycles, higher than the production by the homofermentative strain. However, as in Experiment I,in the treatments with FT025B strain the production of glycerol was lower even than in the control treatment, this is the first record of lower production of glycerol by yeasts that are in the presence of bacterial contamination. It is suggested that the lactic acid and acetic acid along with ethanol, may have acted synergistically in yeasts metabolism and growth, resulting in reduced alcoholic yields. It is also likely that the bacterial strains heterofermentatives were better able to resist the high ethanol levels excreted by yeasts and found in industrial process, since they are also able to produce this compound.
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Yan, Xibo. "Heptyl mannoside based polymers and nanocapsules : Towards potent anti-adhesive glycomaterials and nanocarriers." Thesis, Lyon, INSA, 2015. http://www.theses.fr/2015ISAL0011/document.
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Ce travail de thèse est consacré à la préparation de glycopolymères porteurs de groupements pendants mannoside d’heptyle et à l’évaluation de la capacité de ces ligands multivalents à inhiber la fixation bactérienne sur les cellules humaines. Nous avons synthétisé, par polymérisation radicalaire contrôlée, une série de glycopolymères linéaires ou en étoile présentant des masses molaires, des densités en mannoside et des microstructures modulables dans le but d’évaluer l’influence de ces paramètres sur les processus d’interactions avec diverses souches de bactéries E coli (AIEC LF82 et UTI 89). Nous avons tout d’abord mis en évidence par diffusion dynamique et statique de la lumière, la formation d’agrégats entre ces glycopolymères et FimH, la lectine à l’origine de la fixation de souches de bactéries E coli, traduisant des interactions fortes entre les motifs mannosides et les sites de reconnaissance au mannose de la lectine. Nous avons ensuite évalué l’aptitude de ces ligands multivalents à bloquer l’adhésion bactérienne d’AIEC LF82 (impliquée dans la maladie de Crohn) sur des cellules épithéliales intestinales T84. Il a été démontré en conditions in vitro que l’ajout de 10 nM ou 100 nM d’unités mannoside (respectivement en pré- ou post-incubation) réduit de moitié l’adhésion des bactéries sur les cellules épithéliales. L’effet anti-adhésif de ces glycopolymères a été confirmé par des tests ex vivo réalisés sur des intestins isolés de souris transgéniques CEABAC10. Enfin, nous avons exploité la technique de nanoprécipitation pour l’élaboration de nanocapsules de glycopolymères à cœur huileux. Le procédé développé permet la synthèse de nanocapsules de dimensions contrôlées, porteuses de groupements fonctionnels (fluorophores, ligands) ou de particules métalliques et l’encapsulation de molécules actives à cœur en une seule étapeThis PhD work focuses on the preparation of glycopolymers bearing pendent heptyl mannose groups and the evaluation of the capability of such multivalent ligands to inhibit bacterial adhesion to human cells. Aiming at understanding the impact of various structural parameters on glycopolymer/ E coli interactions (AIEC LF82 et UTI 89 strains of E. coli), a series of linear and star-shaped glycopolymers with tunable molecular weight, mannoside density and microstructure (block copolymers, gradient copolymers, random copolymers) has been constructed. The association of the glycopolymers with FimH adhesin, a lectin which possesses a mannose-specific receptor site and is responsible for recognition and binding to host cells, was first confirmed by static and dynamic light scattering experiments. The propensity of the glycopolymers to prevent attachment of E. coli (AIEC LF82 involved in Crohn’s disease) to intestinal epithelial cells (T84 cells) was further investigated through adhesion assays. It was shown that under in vitro conditions, the addition of 10 nM or 100 nM of glycopolymer on a mannose unit basis (in pre-incubation and post-incubation respectively) decreases by half the bacterial adhesion to intestinal epithelial cells. The anti-adhesive effect of these multivalent ligands was further confirmed in ex vivo conditions for colonic loops of transgenic CEABAC10 mice (Crohn’s disease model mouse). Finally we took advantage of the nanoprecipitation process to generate glyconanocapsules with oily core. The employed strategy allowed for preparing well-defined nanocapsules bearing groups of interest (tags, ligands) or metal particles within the shell and loaded with active molecules in the core in one step
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Chapuis-Goudy, Catherine. "Etude quantitative des effets inhibiteurs de l'environnement sur la croissance des flores microbiennes sur milieu solide." Lyon 1, 1995. http://www.theses.fr/1995LYO10282.
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La colonisation des surfaces par les bacteries sous forme de colonies, d'agregats ou de biofilms est un phenomene ubiquitaire dans la plupart des ecosystemes naturels. Les bacteries y constituent des communautes dont la composition est gouverne par l'equilibre biologique cree par les interactions entre les individus de la communaute. La connaissance des principes de la croissance a la surface d'un milieu solide et des effets induits par les contraintes environnementales est donc d'importance fondamentale. Dans la premiere partie nous etudions au sein d'une meme espece l'influence, sur la taille des colonies, du nombre de colonies presentes sur la surface etudiee. Nous proposons et validons un modele descriptif de cette interaction monospecifique, prealable indispensable a toute etude et estimation d'un effet exterieur a la culture sur le developpement bacterien. La deuxieme partie traite des interactions entre micro-organismes: un modele d'interaction inhibitrice base sur la diffusion d'une substance toxique est developpe. Ce modele est teste sur des donnees experimentales mettant en presence pseudomonas aeruginosa avec d'une part micrococcus spp. Et d'autre par staphylococcus aureus. La derniere partie de ce travail traite de l'effet substance inhibitrice sur la croissance bacterienne sur agar. L'etude et la modelisation des phenomenes d'inhibition bacterienne lors de processus telle la secretion de substances toxiques naturelles comme les bacteriocines ou les enzymes lytiques rend necessaire l'etude de la sensibilite des bacteries aux antibacteriens naturels ou synthetiques. C'est aussi le principe de l'etude de l'action des antibiotiques au laboratoire. Nous proposons une nouvelle methode utilisable de determination de la sensibilite bacterienne aux antibiotiques, basee sur la mesure de la concentration inhibitrice en diffusion
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Souza, Ivanete Ferreira de. "Prospecção de substâncias com atividade antagonista á Candida albicans produzida por bactéria endofítica da região amazônica." Universidade Federal do Amazonas, 2016. http://tede.ufam.edu.br/handle/tede/5549.
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The Amazon Biodiversity symbolize Is a great potential to Discovery of new bacterial straight producer of active biomolecules with importance biotechnological as antimycotics that can be producing by endophytic microorganisms whose the object may be the yeast Candida albicans. This yeast is present in the human body as commensally, being able to cause serious infections, especially in individual immune depressed by diseases as cancer, AIDS and diabetes. It is resistant to antifungal available actually. This way, the object this study was find, from the Amazon bacteria, a bacteria able of produce actives molecules against the C. Albicans yeast, with a purpose to make the production of a active extract that make possible to fractionate and purify the active substance. In the search this anti-candida substance after a analysis of bacteria from different habitats as Waters of the Rio Negro and Solimões and strains derived from endophytic bacteria work collection of Applied Genetics Laboratory Health and Biotechnology of UEA, initially had their potential antimicrobial tested against different pathogenic organisms (Mycobacterium smegmatis, Pseudomlmonasae ruginosa and Staphylococcus aureaus) by cross streaking. The potentials microorganisms were selected and identified by morphology and for sequences of the 16S rDNA region. The growth was made in two different culture media to production of crud extract. The verification the anti-candida action was by diffusion tests in Agar and the quantification was through the Minimum Inhibitory Concentration (MIC). The extract produced was pré-purified by chromatography in open column and was applied thin layer chromatography (TLC) to check the fractions obtained. In total six endopthytic bacteria were selected because they had antimicrobial activity against at least one of pathogens tested, but only the bacteria 229 presented active against C. albicans being cultivate to produce of extract and possibility of identified of anti-candida substance. The culture media that showed better production of biomolecules was the ISP2, according to analysis of size of the halos from of the extract produced. The colony growth was identified as B. amyloliquefaciens and morphologically characterized as Gram positive bacilli The pré-purification resulted in two actives fractions as MIC of 0,25 and 0,5 ug.mL-1 . This way, conclude that in Amazon is possible the identify of bacteria with pharmacological activities from which can be produce antimycotic molecules.
A Biodiversidade Amazônica representa um grande potencial para descoberta de novas linhagens bacterianas produtoras de biomoléculas ativas de importância biotecnológica, como os antimicóticos que podem ser produzidos por microrganismos endofíticos cujo o alvo pode ser a levedura Candida albicans. Esta levedura está presente no corpo humano de forma comensal, sendo capaz de ocasionar graves infecções, principalmente em individuos com o sistema imunológico debilitado por doenças como câncer, AIDS e diabetes. Ela apresenta resistência aos antifúngicos disponíveis na atualidade. Desta forma, o objetivo deste trabalho foi encontrar, a partir de bactérias da Amazônia, uma bactéria capaz de produzir moléculas ativa contra a levedura C. albicans afim de fazer a produção de um extrato ativo que fosse possível fracionar e purificar a substância ativa. Na busca desta substância anti-candida, após a análise de bactérias de diversos habitats como águas dos Rios Negro e Solimões e de cepas oriundas de coleção de trabalho de bactérias endofiticas do Laboratório de Genética Aplicada a Sáude e a Biotecnologia da UEA tiveram inicialmente seu potencial antimicrobiano testado frente a diferentes microrganismos patogênicos (Micobacterium smegmatis, Pseudomonas aeruginosa e Staphylococcus aureus) por estrias cruzadas. Os microrganismos com potencial foram selecionados e identificados por morfológia e pelas sequências da região 16S do rDNA. Fez-se o cultivo em dois meios de cultura diferentes para produção do extrato bruto. A verificação da ação anti-candida foi por testes de difusão em ágar e a quantificação desta através da Concentração Mínima Inibitória (CIM). O extrato produzido foi pré-purificado por cromatografia em coluna aberta e aplicou-se cromatografia em camada delgada (CCD) para acompanhamento das frações obtidas. Ao total seis bactérias endofíticas foram selecionadas por apresentarem atividade antimicrobiana contra ao menos um dos patógenos testados, porém, somente a bactéria 229 apresentou-se ativa contra C. albicans sendo cultivada para produção do extrato e tentativa de identificação da substância anti-candida. O meio de cultura que apresentou melhor produção da biomolécula foi o ISP2, conforme avaliação do tamanho dos halos a partir do extrato produzido. A colônia cultivada foi identificada como Bacillus amyloliquefaciens e caracterizada morfologicamente como bacilos Gram positivo. A pre-purificação resultou em duas frações ativas com CIM de 0,25 e 0,5 ug.mL-1. Conclui-se desta maneira que na Amazônia é possível a identificação de bactérias com atividades farmacológicas a partir das quais pode-se produzir moléculas antimicóticas
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Moraes, Paula Mendonça. "Identificação molecular de bactérias ácido láticas isoladas de leite cru e queijo, e pesquisa de genes de bacteriocinas." Universidade Federal de Viçosa, 2011. http://locus.ufv.br/handle/123456789/5053.
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Previous issue date: 2011-02-16Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Considering the importance of the lactic acid bacteria (LAB) as biopreservatives, and their inhibitory potencial against pathogens and spoilage microrganisms, the aim of this study was identify using molecular methodologies LAB isolates obtained from raw milk and soft cheese, and to conduct a detailed study about the presence of bacteriocin codifying genes. There were utilized 101 LAB isolates previously characterized as antagonist against Listeria monocytogenes. All LAB were submitted to 16S rDNA sequencing. Considering identified genera, specific bacteriocin codifying genes were analised. Based on their antimicrobial activity and presence of nisin genes, 10 Lactococcus spp. isolates were selected and submitted to nisin codifying gene sequencing and translation, for further comparison of predicted proteins. Enterococcus spp. were submitted to phenotipic evaluation of pathogenicity factors. Considering the 16S rDNA sequencing, the most frequent genera obtained were Enterococcus, Lactococcus e Lactobacillus. Most of the analysed isolates (80%) presented at least one bacteriocin codifying gene, being the lantibiothics the most frequent, followed by nisin and enterocin P. Concerning the translated sequences of nisin codifying gene, two variations were observed: substitution of histidine for asparagine (position 27) in two cultures, typical of nisin Z variation, and the substitution of an histidine for threonine (position 31) in three cultures, a nisin variation not described until now. Concerning the Enterococcus spp. pathogenicity factors, only incomplete haemolysis in horse blood agar and gelatinase production were observed in 23 e 11 isolates, respectively. In conclusion, the evaluated cultures presented great potential to be used as biopreservatives in food, specially the genera Lactococcus wich carry the nisin variants codifying genes not described yet in the literature.
Considerando a importância das bactérias ácido láticas (BAL) como bioconservantes, devido a seu potencial inibidor de patógenos e microrganismos deteriorantes, o objetivo deste trabalho foi identificar por metodologias moleculares isolados desse grupo obtidos de leite cru e queijo frescal, e realizar um estudo detalhado quanto a presença de diversos genes de bacteriocinas. Foram utilizados 101 isolados de BAL previamente caracterizados como antagonistas contra Listeria monocytogenes. Todas as BAL foram submetidas à sequenciamento do gene 16S rDNA para identificação. Considerando os resultados obtidos, genes de bacteriocinas produzidas pelos diferentes gêneros identificados foram pesquisados. Alguns isolados identificados como Lactococcus spp. (10) foram selecionados considerando os resultados de atividade antimicrobiana e apresença de genes de nisina, e submetidos ao seqüenciamento e tradução desses genes para comparação as demais sequencias traduzidas. Os isolados do gênero Enterococcus spp. foram submetidos à ànalises fenotípicas de alguns fatores de patogenicidade. Considerando os resultados obtidos, os gêneros identificados foram principalmente Enterococcus, Lactococcus e Lactobacillus. Grande parte dos isolados (80%) apresentou genes para produção de ao menos uma bacteriocina, sendo mais comuns resultados positivos para lantibióticos, e especificamente para nisina e enterocina P. Na análise das seqüências traduzidas de nisina, foram observadas duas variações: substituição da histidina por asparagina (posição 27) em dois isolados (alteração típica da nisina Z), e substituição da histidina por uma treonina (posição 31) em três isolados (variação ainda não descrita). Quanto aos fatores de patogenicidade de Enterococcus spp., apenas hemólise incompleta em ágar sangue de cavalo e produção de gelatinase foram observadas em 23 e 11 isolados, respectivamente. Considerando os resultados obtidos, os isolados avaliados apresentam grande potencial como bioconservadores em alimentos, especialmente os isolados do gênero Lactococcus carreadores de genes responsáveis por produção de variantes da nisina não descritos na literatura.
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Guinot, Philippe. "Contribution au developpement d'un antagoniste du paf dans le sepsis severe a bacilles a gram negatif." Clermont-Ferrand 1, 1994. http://www.theses.fr/1994CLF1MM02.
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Hernández, Torres Daniela Sandra. "Evaluación de la sensibilidad de la bacteria antagonista Serratia plymuthica cepa CCGG2742 a fungicidas de uso común en vid (Vitis vinifera L.)." Tesis, Universidad de Chile, 2013. http://repositorio.uchile.cl/handle/2250/148005.
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Memoria para optar al título profesional de: Ingeniero Agrónomo Mención: Sanidad VegetalLa pudrición gris, causada por el hongo Botrytis cinerea, corresponde al principal problema fitopatológico que enfrentan los productores de uva de mesa, puesto que limita su producción y exportación al desarrollarse pudriciones incluso en almacenaje. Para su control, se integran diferentes medidas entre las cuales el uso de fungicidas específicos es la base de los programas utilizados. Actualmente, la creciente preocupación por la presencia de residuos de fungicidas en la fruta y el riesgo ambiental asociado a su uso, además del desarrollo de resistencias en Botrytis a estas moléculas, han complicado su empleo como estrategia de control. Ante el cual se han aplicado métodos alternativos como la intensificación de prácticas culturales que disminuyan las condiciones predisponentes de la enfermedad, junto a herramientas naturales que incluyen el uso de extractos de cítricos y controladores biológicos como Trichoderma. Por otro lado, recientemente se ha elaborado un biofungicida con la bacteria antagonista Serratia plymuthica cepa CCGG2742, un controlador biológico de B. cinerea, que en este ensayo se ha probado su sensibilidad frente a fungicidas de uso común en vid, con el objeto de conocer su compatibilidad en un posible programa de control que integre estas estrategias. Se evaluaron los ingredientes activos boscalid, ciprodinil + fludioxonil, fenhexamida, iprodione, kresoxim methyl, pyrimethanil, tebuconazole y extracto de cítrico en concentraciones que fluctuaron entre 0 y 5.000 µg i.a. ∙ mL-1 y se calculó la EC50. Los valores de EC50 obtenidos fueron: 6,00∙104 ; 3,18∙107 ; 7,04∙1012 y 1,38∙1018 µg i.a. ∙ mL-1 , para fenhexamida, extracto de cítrico, tebuconazole y boscalid respectivamente, mientras que con iprodione, kresoxim methyl, pyrimethanil y la mezcla de c+f, no se obtuvieron valores de EC50 positivos, ni indicios de inhibición in vitro. De acuerdo a estos resultados, el uso de dosis comerciales de fungicidas no altera el desarrollo de la cepa CCGG2742.
Gray mold induced by Botrytis cinerea, is the most important disease of table grapes that causes significant losses to grape growers. Its ability to attack in the orchard and its ability to develop under conditions prevailing during storage, shipment and marketing make its control a challenge. Control programs have relied mainly on chemical strategies using specific fungicides. However, the growing public concern about fungicide residues in fruit, and the environmental risk associated to fungicide use, in addition to pathogen’s resistance development, have created a complicated situation for the continuous use of fungicides. Therefore, alternative methods have been developed for non-chemical control, such as cultural practices, and the use of natural products including citrus extracts and biological controls agents, as Trichoderma. Serratia plymuthica, antagonistic to B. cinerea, is a new biocontrol agent, and in this study the sensitivity of the strain CCGG2742 to fungicides commonly used in vineyards was tested, in order to know their compatibility for possible control programs that integrate these tools. Boscalid, ciprodinil + fludioxonil, fenhexamida, iprodione, kresoxim methyl, pyrimethanil, tebuconazole and citric extract were tested at concentrations ranging between 0 and 5,000 µg i.a. ∙ mL-1 . EC50 values obtained ranged between 5.48∙104 and 1.38∙1018 µg i.a. ∙ mL-1 . According to these results, commercial rates of the fungicides tested do not affect the development of S. plymuthica strain CCGG2742.
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Ortolani, Maria Beatriz Tassinari. "Bactérias ácido láticas autóctones de leite cru e queijo minas frescal: isolamento de culturas bacteriocinogênicas, caracterização da atividade antagonista e identificação molecular." Universidade Federal de Viçosa, 2009. http://locus.ufv.br/handle/123456789/4974.
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Previous issue date: 2009-02-13The poor microbiological quality of Brazilian raw milk as a result of poor hygienic conditions usually observed during the production. As consequence, raw milk and dairy products present high levels of hygiene indicators microorganisms, suggesting the presence of pathogens. However, pathogens have low competitive ability, suffering direct interference of the autochthonous microbiota of these products. This interference is confirmed by the low occurrence of pathogens in milk and dairy products with poor microbiological quality. Lactic acid bacteria (LAB) are the main member of dairy microbiota that establishes this interference, due their ability of producing several antimicrobial substances, like bacteriocins. Innumerable bacteriocins are described in literature, such as nisin, plantaricin and enterocins, and they are characterized by their antagonistic activity against pathogens and spoilage microorganisms, and they are often used as tools for food safety. The objectives of this study were characterize the microbiota of raw milk and soft cheese, associate the LAB population with other microbiological indicators, detect LAB that present antagonistic activity and characterize their bacteriocinogenic nature, identify the antagonistic cultures by genetic sequencing, and detect the presence of nisin genes. Raw milk samples (n = 36) and raw milk soft cheese (n = 18) were collected in Viçosa region, MG and submitted to microbiological analysis for mesophilic aerobes, total coliforms, Escherichia coli, LAB, Coagulase positive Staphylococcus (CPS), Listeria monocytogenes and Salmonella sp. Considering the LAB enumeration plates, 389 cultures were randomly selected and evaluated to the production of antimicrobial substances against L. monocytogenes, S. aureus, Salmonella Typhimurium and Lactobacillus sakei, and to the production of bacteriocins against L. monocytogenes. 20 bacteriocinogenic cultures were submitted to enzymatic tests to confirm the protein nature of antagonistic substances, molecular identification by genetic sequencing and phylogenetic analysis. The cultures identified as Lactococcus lactis subsp. lactis were submitted to polymerase chain reaction in order to detect genes related to nisin codification. The analyzed samples presented higher counts of hygiene indicators microorganisms and LAB, low counts of E. coli and CPS, and absence of Salmonella sp. and L. monocytogenes. LAB populations presented high correlation indexes with mesophilic aerobes, suggesting the effective participation of this group in the microbiota of the samples. It was observed high frequencies of samples presenting autochthonous LAB with antagonistic activity against the target microorganisms, except against S. Typhimurium. 58 (14.9%) LAB cultures presented bacteriocinogenic activity against L. monocytogenes. The LAB cultures submitted to enzymatic tests presented distinct patterns of enzymes sensitivity, confirming the bacteriocins production. The bacteriocinogenic cultures were identified as Lb. plantarum (2) and Lc. lactis subsp. lactis (18) with genetic similarity to several strains and grouped in distinct phylogenetic groups. Considering the 18 L. lactis subsp. lactis, 7 presented genes related to nisin codification. The obtained results indicate the presence of bacteriocinogenic LAB as natural compounds of raw milk and soft cheese microbiota, presenting antagonistic activity against pathogens. The wide variability genetic and bacteriocins production of these cultures indicate their potential for controlling L. monocytogenes in foods.
A qualidade microbiológica do leite cru brasileiro é reflexo das precárias condições de higiene usualmente observadas em sua produção. Como consequência, esse produto e seus derivados apresentam altas contagens de microrganismos indicadores de higiene, sugerindo a presença de patógenos. Entretanto, devido a sua fraca capacidade de competição, os patógenos sofrem interferência direta da microbiota autóctone desses produtos. Essa interação é confirmada pela baixa ocorrência desses microrganismos em leite e derivados com elevadas contagens de indicadores de higiene. As bactérias ácido láticas (BAL) são os principais componentes da microbiota láctea que determinam essa interferência, pela habilidade de produzir diversas substâncias com atividade antimicrobiana, como as bacteriocinas. Diversas bacteriocinas são descritas na literatura, como nisina, plantaricina e enterocinas, e são caracterizadas por possuírem atividade antagonista contra diversos patógenos e microrganismos deteriorantes, sendo frequentemente utilizadas como ferramentas para garantia da segurança alimentar. Os objetivos desse estudo foram caracterizar a microbiota de amostras de leite cru e queijo minas frescal, relacionar as populações de BAL com a de outros grupos naturalmente presentes, detectar BAL com atividade antagonista e caracterizar sua natureza bacteriocinogênica, identificar essas culturas por sequenciamento genético, e detectar a presença de genes codificadores de nisina. Amostras de leite cru (n = 36) e queijo minas frescal produzido com leite cru (n = 18) foram coletadas na região de Viçosa, MG e submetidas à pesquisa de aeróbios mesófilos, coliformes totais e Escherichia coli, BAL, Estafilococos coagulase positivoss (ECP), Listeria monocytogenes e Salmonella sp. A partir das placas semeadas para enumeração de BAL, 389 culturas foram aleatoriamente selecionadas e avaliadas quanto à produção de substâncias antimicrobianas com atividade contra L. monocytogenes, S. aureus, Salmonella Typhimurium e Lactobacillus sakei, e quanto à produção de bacteriocinas contra L. monocytogenes. Vinte culturas identificadas como bacteriocinogênicas foram submetidas a testes enzimáticos para confirmação da natureza protéica, à identificação molecular e análise filogenética. O DNA das culturas identificadas como Lactococcus lactis subsp. lactis foram submetidas à reação em cadeia da polimerase para detecção de genes codificadores de nisina. As amostras analisadas apresentaram altas contagens de indicadores de higiene e BAL, baixas contagens de E. coli e ECP e ausência de Salmonella sp. ou L. monocytogenes. As populações de BAL apresentam alta correlação com as populações de aeróbios mesófilos, sugerindo a participação efetiva desse grupo na microbiota das amostras. Foram observadas altas frequências de amostras contendo BAL com atividade antagonista contra os microrganismos alvo, com exceção à S. Typhimurium. Cinquenta e oito (14,9%) culturas de BAL apresentaram atividade bacteriocinogênica contra L. monocytogenes. As culturas submetidas à confirmação da natureza protéica das substâncias antimicrobianas apresentaram distintos padrões de sensibilidade a enzimas, confirmando a produção de bacteriocinas. As culturas bacteriocinogênicas foram identificadas como Lactobacillus plantarum (2) e Lc. lactis subsp. lactis (18), com similaridade genética em diferentes isolados, e agrupadas em diferentes grupos filogenéticos. Das 18 culturas identificas como Lc. lactis subsp. lactis, 7 apresentaram genes relacionados a codificação de nisina. Os resultados obtidos indicam a presença de BAL bacteriocinogênicas como constituintes da microbiota de leite cru e queijo minas frescal, com potencial antagonista contra patógenos. Essas culturas apresentaram diferentes perfis genéticos e quanto à produção de bacteriocinas, revelando seu uso potencial no controle de L. monocytogenes em alimentos.
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Cheng, Yunfeng. "Development of Boronic Acid Flurescent Reporters, Boronic Acid-Modified Thymidine Triphosphates for Sensor Design and Antagonists of Bacterial Quorum Sensing in Vibrio Harveyi." Digital Archive @ GSU, 2011. http://digitalarchive.gsu.edu/chemistry_diss/58.
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Carbohydrates are known to play important roles in a large number of physiological and pathological processes. Conceivably, “binders” of carbohydrates of biological importance could be used as diagnostic and therapeutic agents. Currently, lectins are the major available tools in research for carbohydrate recognition. However, the available lectins often have cross-reactivity issues, along with the high costs and stability issues. Therefore, there is a critical need to develop alternatives (lectin mimics). In this regard, there have been very active efforts in developing different “binders”, such as small molecule lectinmimics and aptamers. Among all the small molecule lectinbmimics developments, boronic acid stands out as the most important building blocks of the sensors design for carbohydrates biomarkers due to its intrinsic binding affinities with diols. To address a fundamental question that whether boronic acid also binds to six-membered ring sugars, with very limited precedents, we provided a concrete experimental evidence of the binding. Specifically, a series of isoquinolinylboronic acids were found to have remarkably high binding affinities with fluorescence change upon binding to representative sugars. Most importantly, these isoquinolinylboronic aicds showed weak but very encouraging bindings with six-membered sugar model. All these promising results paves the way of using boronic acids, especially isoquinolinylboronic acid as building blocks for chemosensors design for biological carbohydrates biomarkers, which universally contain six-membered ring and liner diols.
Aptamer provides another alternative way for sensors development for carbohydrates biomarkers as lectin mimics. Compared to lectins, they are normally cheaper and more stable. However, there is much less options. Another challenging area for aptamer-based lectin mimics development is the difficulty to differentiate changes in glycosylation patterns of a glycoprotein, which affect the function of a glycoprotein and thus recognized as biomarkers. To address this major challenge, our group first demonstrated that the incorporation of a boronic acid into DNA would allow for the aptamer selection process to gravitate towards the glycosylation site. To examine the generality of boronic acid incorporation, increase the structural diversity, and broaden the application of boronic acid-modified DNA, a series of B-TTP analogues with simplified structures were designed, synthesized, and successfully incorporated into DNA. A simple route was also developed using 1,7-octadiyne as a linker for both Sonogashira coupling with thymidine and CuAAC tethering of a boronic acid moiety. This paves the way for the preparation of a large number of B-TTPs with different structural features for aptamer selection or array analysis.
Finally, bacterial quorum sensing has received much attention in recent years because of its relevance to pathological events such as biofilm formation. As one of the very first groups that developed a series of antagonists for AI-2 mediated quorum sensing, we herein designed and synthesized a series of analogues based on the structures of two lead inhibitors identified through virtual screening. Besides, we also examined their inhibitory activities, twelve of which showed equal or better inhibitory activities compared with the lead inhibitors. The best compound showed an IC50 of about 6 mM in a whole cell assay using Vibrio harveyi as the model organism. This encouraging results and SAR discuss also paves the way for the finding of more potent compound through further structure optimization.
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Ulmer, Jonathan Edward. "Analysis and studies of inhibition of the two divergent thymidine biosynthesis pathways in Mycobacterium tuberculosis /." Thesis, Connect to this title online; UW restricted, 2007. http://hdl.handle.net/1773/10297.
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Marquardt, Daniel [Verfasser]. "Field assessment of the influence of a seed treatment with the antagonistic bacterium Serratia plymuthica on the control of major rapeseed pathogens in Brassica napus / Daniel Marquardt." Kiel : Universitätsbibliothek Kiel, 2012. http://d-nb.info/102387041X/34.
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Díaz, Camezán Yohana Lisset. "Aislamiento y caracterización de cepas nativas de Bacillus spp y Trichoderma spp de la rizosfera de cafeto con potencial antagonista frente a Fusarium oxysporum del valle de Monzón – Huánuco-Perú." Bachelor's thesis, Universidad Nacional Mayor de San Marcos, 2019. https://hdl.handle.net/20.500.12672/10188.
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El cafeto (Coffea arábica, L.) es uno de los principales productos de la canasta agroexportadora peruana, hecho que ha contribuido con el desarrollo económico y social del Perú. Sin embargo este se ve afectado por enfermedades fúngicas como la pudrición vascular causado por Fusarium oxysporum, reduciendo el sistema radicular en más de 90% afectando la producción y calidad. Por ello, se busca aislar cepas nativas de Bacillus y Trichoderma de rizósfera de café con capacidad antagonista frente a Fusarium oxysporum que puedan utilizarse en programa de manejo integrado de plagas del cafeto, en el distrito de Monzón, región Huánuco. Se logró aislar 30 cepas de Bacillus ssp. y 20 cepas de Trichoderma spp las mismas que fueron evaluadas por su capacidad antagonista frente al patógeno F. oxysporum, siguiendo la metodología de enfrentamiento directo dual en el medio Agar Papa Dextrosa . Se realizó pruebas bioquímicas, caracterización macroscopica y microscópica a las cepas con actividad antagonista y se identificó por claves taxonómicas. Las 9 cepas de Trichoderma (M3PI.I, B1.T, MTS.I, MT5.A, MT12.A, PLSO1, TL7.R, MT24.I, MT14.e) y 6 cepas de Bacillus (MT1.I, MT1.II, MT2.I, MT2.II, MT7, MT3P3) con actividad antagonista; siendo la cepa M3PI.I la que alcanzó 80 % de actividad de inhibición del fitopatogeno. Las cepas con mayor actividad antagonista (MT3P3, B1.T, MTS.I) fueron identificadas molecularmente como Trichoderma sp, Trichoderma asperellum, Trichoderma sp respectivamente. Las cepas aisladas de Bacillus sp y Trichoderma sp podrían considerarse como potenciales biocontroladores de pudrición vascular en cafeto representando una nueva vía de trabajo en pro de una agricultura sostenible.Tesis
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Casteliani, Ana Gabriele Barbosa. "Estrutura e diversidade das comunidades bacterianas associadas à Triticum aestivum L. e potencial antagonista contra os fitopatógenos Pyricularia grisea e Fusarium graminearum." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/11/11138/tde-18042017-103056/.
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A cultura de trigo (Triticum aestivum L.) é a segunda maior do mundo e o Brasil ocupa o segundo lugar de produção na América do sul. Entretanto, a produtividade desta cultura pode ser limitada devido à ocorrência de doenças como a brusone, causada pelo fungo Pyricularia grisea e a doença denominada giberela, causada pelo fungo Fusarium graminearum Populações bacterianas associadas à rizosfera de trigo podem apresentar potencial como agentes de controle biológico de diferentes fitopatógenos. Neste contexto, esta pesquisa foi direcionada ao estudo da composição da comunidade bacteriana rizosférica do trigo e a busca por micro-organismos com potencial para o controle biológico da brusone e da giberela. Assim, para melhor compreensão das comunidades associadas ao trigo, foram realizadas coletas em duas regiões diferentes no Brasil, sendo possível a obtenção de 606 estirpes entre bactérias e actinobactérias da rizosfera do trigo e de solo de cultivo da mesma cultura. Destas, 16 apresentaram, em testes in vitro, potencial antagonista diante dos fungos fitopatogênicos Pyricularia grisea e Fusarium graminearum com diferentes porcentagens de inibição. Dez dos isolados selecionados apresentaram similaridade com a família Streptomycetaceae, porém, quatro linhagens necessitam de estudos mais detalhados, pois a similaridade foi baixa, podendo indicar uma espécie ainda não descrita; quatro linhagens demonstraram similaridade com a família Bacillaceae e dois com a família Paenibacillaceae. Na avaliação de produção de metabólitos secundários com efeito inibitório, apenas dez apresentam potencial, porém estudos mais detalhados se fazem necessários para a confirmação deste mecanismo. A análise de diversidade bacteriana demonstrou uma maior abundância do filo Actinobacteria, seguido pelo filo Proteobacteria e Acidobacteria em ambas as áreas amostradas, entretanto, o filo Acidobacteria foi o que demonstrou a maior variação entre as classes presentes nas diferentes regiões estudadas, indicando uma seleção da comunidade de acordo com a variedade do cultivar e o estádio de desenvolvimento do vegetal. A comunidade bacteriana de trigo apresenta micro-organismos com potencial para a inibição dos fungos causadores da brusone e da giberela, porém o efeito destas linhagens deve ser melhor investigado em condições de campo. A compreensão das comunidades bacterianas associadas ao trigo pode se apresentar como uma importante ferramenta para direcionar a busca por antagonistas.Wheat (Triticum aestivum) is the second largest crop in the world and Brazil is in the second position in the ranking of production in South America. However, its productivity can be limited due to the occurrence of diseases like wheat blast, caused by the fungus Pyricularia grisea and the disease called Fusarium head blight (FHB), caused by the fungus Fusarium graminearum. Bacterial populations associated to wheat rhizosphere may have potential to act as biological control agents of different plant pathogens. In this context, this research aimed to look at wheat rhizosphere bacterial community and the pursuit of microorganisms with potential for the biological control of wheat blast and FHB. Given this, in order to study wheat bacterial communities, data collection was carried out in two different regions in Brazil, returning 606 bacterial and actinomycetes isolates from wheat rhizosphere and bulk soil. Among these,, 16 strains revealed antagonistic potential against both plant pathogens Pyricularia grisea and Fusarium graminearum, with different percentages of inhibition. Ten strains were selected out of the 16 and showed similarity with the family Streptomycetaceae, whereas four of them displayed a low similarity, requiring a deeper analysis and might indicate new species. Four isolates showed similarity with the family Bacillaceae and two with the family Paenibacillaceae. On the assessment of production of secondary metabolites with inhibitory effects, only ten strains were positive, but more detailed studies are necessary to confirm this mechanism. The analysis of bacterial diversity revealed a larger abundance of the phylum Actinobacteria, followed by the phylum Proteobacteria and Acidobacteria in both areas, however, the phylum Acidobacteria revealed more variation among its classes when both araes were compared, indicating a selection of the community according to the cultivar and the developmental stage. Wheat bacterial community presents microorganism with inhibition potential against fungi responsible for wheat blast and FHB, yet the effect of such strains should be investigated closely under field conditions. The understanding of bacterial communities associated to wheat may be seen as an important tool to help in the search for antagonists.
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Abdou, Mohamed Adam Mohamed [Verfasser]. "Root-knot nematodes: abundance in organic farming, differentiation among populations, microbes attached to juveniles in soil, and bacterial antagonists / Mohamed Adam Mohamed Abdou. Julius Kühn-Institut. Technische Universität Carolo-Wilhelmina zu Braunschweig." Quedlinburg : Julius Kühn-Institut, 2014. http://d-nb.info/1105491455/34.
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Adam, Mohamed [Verfasser]. "Root-knot nematodes: abundance in organic farming, differentiation among populations, microbes attached to juveniles in soil, and bacterial antagonists / Mohamed Adam Mohamed Abdou. Julius Kühn-Institut. Technische Universität Carolo-Wilhelmina zu Braunschweig." Quedlinburg : Julius Kühn-Institut, 2014. http://nbn-resolving.de/urn:nbn:de:101:1-201607056010.
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Zhao, Huifang. "Improved Methods of Sepsis Case Identification and the Effects of Treatment with Low Dose Steroids: A Dissertation." eScholarship@UMMS, 2011. https://escholarship.umassmed.edu/gsbs_diss/529.
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Sepsis is the leading cause of death among critically ill patients and the 10th most common cause of death overall in the United States. The mortality rates increase with severity of the disease, ranging from 15% for sepsis to 60% for septic shock. Patient with sepsis can present varied clinical symptoms depending on the personal predisposition, causal microorganism, organ system involved, and disease severity. To facilitate sepsis diagnosis, the first sepsis consensus definitions was published in 1991 and then updated in 2001. Early recognition of a sepsis patient followed with timely and appropriate treatment and management strategies have been shown to significantly reduce sepsis-related mortality, and allows care to be provided at lower costs. Despite the rapid progress in the knowledge of pathophysiological mechanisms of sepsis and its treatment in the last two decades, identifying patient with sepsis and therapeutic approaches to sepsis and its complications remains challenging to critical care clinicians. Hence, the objectives of this thesis were to 1) evaluate the test characteristics of the two sepsis consensus definitions and delineate the differences in patient profile among patients meeting or not meeting sepsis definitions; 2) determine the relationship between the changes in several physiological parameters before sepsis onset and sepsis, and to determine whether these parameters could be used to identify sepsis in critically ill adults; 3) evaluate the effect of corticosteroids therapy on patient mortality.
Data used in this thesis were prospectively collected from an electronic medical record system for all the adult patients admitted into the seven critical care units (ICUs) in a tertiary medical center. Besides analyzing data at the ICU stay level, we investigated patient information in various time frames, including 24-hour, 12-hour, and 6-hour time windows.
In the first study of this thesis, the 1991 sepsis definition was found to have a high sensitivity of 94.6%, but a low specificity of 61.0%. The 2001 sepsis definition had a slightly increased sensitivity but a decreased specificity, which was 96.9% and 58.3%, respectively. The areas under the ROC curve for the two consensus definitions were similar, but less than optimal. The sensitivity and area under the ROC curve of both definitions were lower at the 24-hour time window level than those of the unit stay level, though the specificity increased slightly. At the time window level, the 1991 definitions performed slightly better than the 2001 definition.
In the second study, minimum systolic blood pressure performed the best, followed by maximum respiratory rate in discriminating sepsis patients from SIRS patients. Maximum heart rate and maximum respiratory rate can differentiate sepsis patients from non-SIRS patients fairly well. The area under ROC of the combination of five physiological parameters was 0.74 and 0.90 for comparing sepsis to non-infectious SIRS patients and comparing sepsis to non-SIRS patients, respectively. Parameters typically performed better in 24-hour windows compared to 6-hour or 12-hour windows.
In the third study, significantly increased hospital mortality and ICU mortality were observed in the group treated with low-dose corticosteroids than the control group based on the propensity score matched comparisons, and multivariate logistic regression analyses after adjustment for propensity score alone, covariates, or propensity score (in deciles) and covariates.
This thesis advances the existing knowledge by systemically evaluating the test characteristics for the 1991 and 2001 sepsis consensus definitions, delineating physiological signs and symptoms of deterioration in the preceding 24 hours prior to sepsis onset, assessing the prediction performances of single or combined physiological parameters, and examining the use of corticosteroids treatment and survival among septic shock patients. In addition, this thesis sets an innovative example on how to use data from electronic medical records as these surveillance systems are becoming increasingly popular. The results of these studies suggest that a more parsimonious set of definitional criteria for sepsis diagnosis are needed to improve sepsis case identification. In addition, continuously monitored physiological parameters could help to identify patients who show signs of deterioration prior to developing sepsis. Last but not least, caution should be used when considering a recommendation on the use of low dose corticosteroids in clinical practice guidelines for the management of sepsis.
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Dixit, Sameer M., University of Western Sydney, and Centre for Advanced Food Research. "Antagonistic activity of probiotic bacteria based on bacterial diversity in the porcine gut." 2004. http://handle.uws.edu.au:8081/1959.7/35614.
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Diversity analysis of Escherichia coli have routinely utilised isolates obtained by culture of faeces on MacConkey selective media, under the assumption that the diversity identified in faecal isolates are representative of similar diversity in E. coli in the gastrointestinal tract (GIT). This study has addressed this important issue by specifically isolating E. coli from different regions of the gut in pigs and subjecting them to enzymatic multilocus enzyme electrophoresis (MLEE) and molecular virulence factor (VF) analysis to ascertain whether E. coli populations inhabiting different regions of the gut are different from each other. Combination of these results showed that on average, E. coli strains isolated from the upper GIT region (small intestine) of the pig are distinctly different from the E. coli strains isolated from the lower GIT region (large intestine). An important aspect of the finding that faecal E. coli are not truly representative of the diversity in the GIT is the mechanism used by specific clonotypes that have adapted to different geographical habitats to survive challenge from incoming strains.Doctor of Philosophy (PhD)
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Chen, Mei-huei, and 陳美惠. "Studies on control of tomato bacterial wilt by endophytic antagonistic bacteria from tomato." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/64399761753765439257.
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碩士國立中興大學
植物病理學系
84
A total of 227 bacterial strains antagonistic to Pseudomonas solanacearum on media were isolated from interior tissues of stems of healthy tomato plants ( 208 strains ) and other sources (welsh onion rhizospheres , tobacco plants ). They were tested for the ability to control tomato bacteria wilt after introducing into plants by the Kijima,s hypocotyl-cuttings method in a screenhouse. Only nine strains can reduce the disease severity significantly. Among the nine strains, strains K8-1、EA2-4、KA4-1 and A10-5 were more consistent in their control efficacy during repeated testing. These four strains were all isolated internaly from the stem of healthy tomato plants, and were termed endophytic antagonistic bacteria in this study. Strain KA8-1 was identified as Bacillus sp., strains KA4-1 and A10-5 as Pseudomonas spp. , but strain EA2-4 could not be identified based on the Biolog identification system. Factors affecting the biocontrol efficacy of the four strains of endophytic antagonistic bacteria by the hypocotyl-cutting method were studied in the greenhouse. The influence of each factor on the control efficacy varied among tested antagonistic bacteria. The antagonistic bacteria were more effective when using 10 and 13-day old seedlings for hypocotyl-cutting treatment than seedlings at the other ages. When soaking period during the hypocotyl-cuttings treatment was too long or short, it was not suitable for all or some strains of the antagonistic bacteria ; the best soaking period was 12 hr. Except strain EA2-4, allstrains showed biocontrol efficacy on susceptible and resistant varieties ( lines ) of tomato. The best concentration of the antagonistic bacteria used for dipping was 108 cfu/ml . Control efficacy of the antagonistic bacteria varied when the disease was caused by different strains of P. solanacearum. The control efficacy of antagonistic bacteria was more easily demonstrable in the soil infested with P. solanacearum at the density of 107 or 106 cfu/g dry soil. Biocontrol efficacy of the antagonistic bacteriawas affected by temperature ; Except strain EA2-4, the best control efficacy was obtained at 30℃. Among different treatment methods of antagonistic bacteria , the hypocotyl-cutting and seed bacterization methods resulted the best control efficacy by all or most strains of the antagonistic bacteria. The antagonistic bacteria existed in stems and roots after introducing into tomato plants by the hypocotyl-cutting method. The populations of antagonistic bacteria declined more slowly in roots than in stems with the time during the growth of tomato. Fourty-two days after introduced into plants, populations of all antagonistic strains in roots and stems remained as 104-106 cfu/g fresh root and 103-105 cfu/g fresh stem, respectively. The population of K8-1 was the highest detected in the plant, which were 1.17×106 cfu/g fresh root and 2.90×105 cfu/g fresh stem, respectively; the population of EA2-4 was the lowest, which were 1.80×104 cfu/g fresh root and 1.35×103 cfu/g fresh stem, respectively.When the antagonistic bacteria and P. solanacearum were present together in the tomato plants, the population dynamics of the antagonistic bacteria in roots and stems were similar to those described above, whereas the populations of P. solanacearum increased with the time. Even though the population of P. solanacearum did not seem to be declined, the disease severities of the plants treated with all antagonistic bacteria were significantly lower than control plants.
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Chen, Chun-Chin, and 陳俊欽. "Application of Antagonistic Bacteria for Controlling Clubroot of Crucifers." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/38695448857365475628.
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碩士國立中興大學
植物病理學系
84
The purpose of this study is to use endophytic and root colonized antaists to control club root disease of crucifers. One hundred and fifteen bacterial strains were isolated either from healthy or slightly diseased cabbage root tissues collected from Ching-jing area. According to analysis of antagonistic ability of these 115 strains against infection of root hairs by Plasmodiophora brassicae, seventeen strains exhibiting the inhibition ability on infection of root hairs in 10 days were selected to evaluate the control ability in pots after six weeks. The results revealed that three out of seventeen strains decreased club root disease index. These three antagonistic strains 10, 73 and 80 were identified as Bacillus spp. and were used as biocontrol agents in further study. Before transplanting the seedlings to infested soil infected with107 spores/g soil, two pretreatments of the seedlings with these antagonistic strains were perfomed. That was, the 10-day-old seedlings with or without cutting at hypocotyl were dipped into antagonistic bacteria suspension (108 cfu/ml) for 12 hours. All three strains of antagonistic bacteria tested reduced club root disease index significantly. The results of population dynamic assay revealed that the population of antigonists declined along with plant growth. In the case the plants have been treated by cutting the seedlings at hypocotyl and dipping into antagonistic bacteria suspension, the population of each strain in stem was declined from 105~106 to 103~104 cfu/g wet stem, and was declined from 106 to 103~105 cfu/g wet root in root during eight weeks period of treatments. Population of all strains in the rhizosphere were declined from 106 to 103~104 cfu/g wet root by dipping root into antagonistic bacteria suspension during eight weeks period of treatments.
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Chan, Shu-Yun, and 詹淑雲. "Biocontrol for fruit diseases of waxapple with antagonistic bacteria." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/85978455595829959294.
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碩士國立屏東科技大學
植物保護系
91
Using self-developed “isolation medium for bacterial antagonist” and “antibiosis testing medium plate”, 21 native isolates of Taiwan antagonistic bacteria were rapidly isolated and screened from leaf surfaces of waxapple, soil solution and air collected from waxapple orchards at Pingtung. Three of them, Bacillus sp. LB5, Paenibacillus polymyxa LB8, and Bacillus sp. LB15 isolates were used as antagonists for testing. Three pathogens of waxapple fruit diseases including anthracnose (Colletotrichum gloeosporioides Penzig)、fruit rot (Pestalotiopsis eugeniae Thuem.), and black rot (Botryodiplodia theobromae Pat.) were used as pathogens for testing. Based on the results of antagonistic experiments including inhibition tests of mycelial growth used with glass-ring containing PSA plates and spore germination, the antagonistic cultivated liquid of PS medium had strong antagonistic efficacy against pathogens increasing with lengthening the culture duration. The antagonistic LB5 or LB8, 10-day cultivated liquid of PS media, and bacterial cell suspension of these two isolates contained very strong antagonistic efficacy, and the long store characteristic for more than 80 days or 1 year, individually. The autoclaved 10-day cultivated liquid of LB5, and autoclaved filtrate of the cultivated liquid through 0.45μm Millipore membrane, all the two kinds of liquid still contained high antagonistic efficiency. The 10-day cultivated liquid of LB5 could keep the persistent ability of antagonism after dropping and drying on the glass slides more than 10 days. LB5 antagonist could tolerate many fungicides and insecticide recommended for controlling the insect pests and diseases of fruit trees. LB5 antagonist could induce unevenly swollen or balloon swollen hyphae and balloon formed cell of conidiospores by its antagonistic effect. LB5 isolate was an antagonistic Bacillus bacterium containing antibiotic effect against pathogenic fungi and an ability of colony rapidly extending, whereas LB8 isolate was an antagonistic bacterium, Paenibacillus polymyxa, containing only the antibiotic effect. For biological control of fruit diseases of waxapple, antagonistic bacterial liquid was prepared from the 10-day cultivated liquid of PS medium made 10-1 dilution, and amended 0.1% soy bean powder and 0.1% sucrose, and sprayed one time at 1 or 2 weeks interval from floral stage to younger fruit stage, and integrated with fruit bagging. According the results of three experiments of biological control on waxapple fruit diseases, two native antagonist bacteria Bacillus sp. LB5 and Paenibacillus polymyxa LB8 isolates were proved to contain a good biocontrol efficacy.
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Lai, Yahn-Liang, and 賴彥良. "Biological control of Fusarium wilt of tomato by antagonistic bacteria." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/30488229237844631671.
Full textAbstract:
碩士國立中興大學
植物病理學系
84
The purpose of this study is to detect the distribution of antagonists withinthe plant and to evaluate the effect of antagonists on control of Fusariumwilt of tomato after introducing antagonists into plant by thehypocotyl- cutting method. Nine isolates of Fusarium oxysporum f.sp.lycopersici (Fol) were collected from Chu Tze Hu, Hsinyi, and Kwantien inTaiwan. Among them, the isolate Fol-04 showed the highest virulence on tomatovareity Know-You 301 in pathogenicity test was used in this study. Based onthe results of evaluating the correlation between the inoculum density ofFol-04 and its disease index with root-prunning and soil infestation method,106 spores / ml and 105 propagules / g soil were selected as inoculumdensities for this study. According to analysis of the antagonistic ability of130 strains against Fol-04 isolates with dural-culture on PDA medium, 74strains expressed the inhibition distance ranging from 0.1~0.5 cm, 45 strainsfrom 0.5 to 1 cm and 11 strains greater than 1 cm. Thirty two strains showingthe inhibition distance greater than 0.7 cm were selected and introduced intotomato plants by the hypocotyl-cutting method to test for the ability ofcontrolling Fusarium wilt of tomato in greenhouse. The results revealed that 6out of 32 strains allowed the survival percentages of plants twice more thannon-treated control. Antagonistic bacterial strains 008, 082, and 085 whichshowed strong ability in disease- controlling were used for furthercharacterization, including their colonization within tomato plants andcontrolling ability. Strains 008 and 082 were Bacillus spp. and 085 strain wasPseudomonas sp. based on the Biolog identification system. The result ofevaluating antagonist populations within the tomato plants showed that thehighest population of these strains were detected in the lower half ofhypocotyl, and consequencely declined in the adventitious roots, the upperhalf of hypocotyl, and epicotyl. It was also found that strain 082 was thebest to spread upward from introducing site, followed by 008 and 085. Thepopulation dynamic of antagonists colonized on roots declined with the timeduring the period of plant growth. Fourteen weeks after introduced antagonistsinto plants, population of 008, 082,and 085 strain on roots remained to be4.1x103 cfu/g wet root, 1.89x104 cfu/g wet root, and 2.18x105 cfu/ g wet root,respectively. Based on the observations under T.E.M., these antagonistslocated in vascular tissues of hypocotyl 12 hours after introduction, and inthe cortex cells 28 days afer introduction. The yield of tomato was notinfluenced after these antagonists were introduced into the plant. Strain 008and 082 reduced significantly tomato Fusarium wilt after inoculation byroot-prunning method, while 085 showed no effectiveness. All theseantagonistic strains significantly reduced the tomato Fusarium wilt afterplants were transplanted in the infested soil.
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Yeh, Jeng-Chyang, and 葉正強. "Studies on the Bacteria in Aquaculture 1.Antagonistic Bacteria of Edwardsiella tarda 2.Culturable Bacteria in Penaeus monodon Pond." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/5s9457.
Full textAbstract:
碩士國立中山大學
海洋資源學系研究所
88
Presently, most bacterial diseases of eel (Anguilla japonica) are controlled by antibiotics. However, antibiotics not only kill the bacterial pathogens but also kill those bacteria which might be beneficial to eels. In the meantime, application of antibiotics may result in spreading and accumulation of the resistance genes which may in turn lower the efficacy the antibiotics in the future and may threat public health. The recent trend to such problems is to screen non-pathogenic bacteria which are competitive to the pathogenic bacteria in the same environments. The eel pathogen, Edwardsiella tarda, was chosen as the target in this study. Bacterial strains were isolated from different eel ponds and tested for the ability to inhibit the growth of E. tarda. Of 2,412 strains tested, eight of them showed the inhibition capability. The molecular weights of the bioactive ingredients are all smaller than 12,000 daltons indicating they are not protein in nature. One of the strains is Bacillus cereus, four of the strains are Bacillus sphaericus, two of the strains are Bacillus laterosporus, and one of the strains of identified as Pseudomonas areuginosa competed extremely well with E. tarda. These antagonistic bacteria may have the potential of becoming as bio-control agents.Tiger shrimp (Penaeus monodon) is an important agricultural product in Taiwan. The over all production peaked in 1988, since then the outbreak of viral infection has caused the shrimp aquaculture a heavy damage. The current production is merely 1/10 of the peak. Many solutions were proposed to solve the problem, such as: increase the immunity of the shrimp, study pumping of the underground water has caused serious land subsidence in the coastal areas. Therefore, conservation of water is the trend of current aquaculture. In this study, culturable bacteria were isolated from a closed tiger shrimp pond. The taxonomy of the bacteria was based on 16S rDNA sequence phylogeny. Roughly 8 groups (genera) of bacteria were identified, including: Vibrio, Pseudoalteromonas, Porphyrobacter, Flavobacterium, Rhodthermus and three uncertain genera.
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Liu, Kuan-Ting, and 劉冠霆. "Screening and application of antagonistic bacteria andplant extracts to control anthracnose disease on mango." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/07448374115196936951.
Full textAbstract:
碩士國立中興大學
植物病理學系所
103
Mango is one of the most important fruit crops and is the highest value of exported fresh fruits in Taiwan. Colletotrichum gloeosporioides causes mango anthracnose and is one of the major pathogens in mango. It can infect mango leaves, flowers, branches and fruit, and causes considerable fruit disqualified during postharvest period. Currently, the disease management strategies majorly rely on fruit bagging and chemical fungicides application. However, fungicide application can result in fungicide resistance and excessive chemical residues. The purpose of this study is to screen and apply microbe- and plant-derived materials to control mango anthracnose. Since mango fruit is seasonally available, a stable inoculation platform for using mango leaf as inoculation material was established in the beginning in my thesis study. Mango (cv. Irwin) leaf with age within 8-days is highly susceptible to the infection of C. gloeosporioides TYC-2 and the infection is stable and repeatable. In addition, anthracnose lesions appeared earlier on the abaxial than the adaxial surface of a leaf, which is not related to the ability of germination and appressorial formation of the pathogen on both surfaces. Among 17 tested plants, ethanol extracts from 4 different plants showed nearly 50% of inhibition on mycelial growth of TYC-2. Plant A ethanol-extracts showed complete inhibition on TYC-2 spore germination at 0.08 mg/ml in vitro. The anthracnose lesion was not appeared when mango leaf and fruit were co-inoculated with TYC-2 and plant A ethanol-extracts (0.08 mg/ml). Total 45 yeast isolates and 83 bacterial isolates were isolated from the soil, leaves or flowers of mango and showed inhibitory ability to the mycelial growth of TYC-2. Among all yeast isolates, isolate 3H-4 showed strong competition against the growth of C. gloeosporioides in PDA medium. Among all bacterial isolates, strain A and B has significant inhibitory effect to 15 Colletotrichum isolates which cause the anthracnose of mango, Chinese cabbage and chili pepper. Strain A and B were identified as Bacillus amyloliquefaciens based on the comparison of 16S rDNA sequence and Biolog analysis. The 100-fold dilution of 4-day-old culture liquid of strain A or B cultured in culture medium (strain A-SSM or strain B-SSM) could completely inhibit anthracnose lesion production on detached leaves and fruit. Moreover, it showed 80% lesion area reduction when treated with 600-fold dilution of strain B-SSM on detached leaf. The bacteria population of strain B -SSM could increase slightly from 1.48 × 109cfu/ml to 2.6 × 109cfu/ml after stored for 20 weeks under room temperature. In addition, the antagonistic activity of strain B -SSM was resistant to heat treatment, 100℃ for 20 minutes. It indicates that strain B -SSM had great stability during short-time storage assay. To improve the antagonistic activity of strain B, various plant oils were added into SSM to culture this bacterial strain. The results showed that 0.5% (v/v) plant oil A amended SSM could increase the antagonistic activity of strain B by increasing the lesion area reduction from 43% to 100% when 200-fold diluted bacterial culture was applied. The active ingredient of strain B -SSM remained in the culture filtrate but not the culture pellets after the bioactivity assay on the detached leaf. Culture filtrate of strain B -SSM could inhibit spore germination and cause abnormal swelling of germ tubes of TYC-2 in vitro and in planta under the examination of light microscopy as well as scanning electron microscopy. There were many vacuole-like structures formed in hyphal 32 h after treated with strain B -SSM, and no necrosis lesion was observed on fruit 72 h after treatment. Thin layer chromatographic (TLC) analysis revealed that two regions (Rf 0.045 and 0.38) with antifungal activity were identified in strain B -SSM and strain B -SSM with 0.5% plant oil A. The bioactive components were recovered from the TLC plate and analyzed by high-performance liquid chromatography (HPLC). The data revealed that the bioactive components contain iturin A. Based on the results presented in this study, the ethanol-extracts of plant A and bacterial strain B has great potential for further development of biological control agents in field applications to control mango anthracnose.
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Ramarathnam, Rajesh. "Mechanisms of phyllosphere biological control of Leptosphaeria maculans, the blackleg pathogen of canola, using antagonistic bacteria." 2008. http://hdl.handle.net/1993/21236.
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Mahdy, Magdy [Verfasser]. "Biological control of plant parasitic nematodes with antagonistic bacteria on different host plants / von Magdy Mahdy." 2002. http://d-nb.info/968566111/34.
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Lin, Lih-Shin, and 林立心. "Characterization of the Secreted Substances from Antagonistic Bacteria which can Inhibit the Growth of Xanthomonas perforans." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/99197407294072431798.
Full textAbstract:
碩士國立中興大學
植物病理學系所
104
Bacterial spot disease is a worldwide-distributed plant disease on solanaceous plants and reduces plant production. Xanthomonas perforans, one of the pathogenic bacteria causes the bacterial spot disease on tomato in Taiwan. The SAn-03 strain, isolated from agricultural soil, was confirmed to have inhibitory ability against X. perforans using confrontation assays. According to the fatty acid profiles and similarity analysis of 16S rDNA and rpoB gene sequences, the SAn-03 strain was identified as Paenibacillus sp. Imaging mass spectrometry (IMS) analysis was employed to investigate the candidate antagonistic compounds, revealed that the candidate substances secreted by SAn-03 in the spectra of 500-600, 800-950, and 1,000-1,100 mass to charge ratio (m/z) might participate in antagonizing X. perforans. Moreover, to elucidate the effects on plant growth upon the inoculation of SAn-03 alone or together with X. perforans, tomato seeds were sown in the soil mixed with SAn-03, the result indicated that germination of seeds and vegetative growth of tomato seedlings are similar to the results performed by water control. Co-inoculation with SAn-03 and X. perforans on tomato by leaf spraying method, exhibited mild symptoms of bacterial spot disease, while the pre-treatment of cell suspension and the diluted culture broth of SAn-03 using leaf spraying method reduced the disease severity of bacterial spot elicited by X. perforans. On the other hand, the weekly drenching inoculation of cell suspension of SAn-03 for 3 weeks prior to the inoculation of X. perforans could increase the length and weight of stem and root of tomato. Moreover, the pre-treatment of cell suspension and the diluted culture filtrate of SAn-03 by drenching method could reduce the disease severity of bacterial spot disease. Altogether, this study revealed that the SAn-03 strain is potential to be a biocontrol agent for controlling bacterial spot diseases on tomato.
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Liu, Yu-Hsuan, and 劉郁瑄. "Evaluation of lactic acid bacteria for antagonistic activity against uropathogenic Escherichia coli in vitro and in vivo." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/3kury8.
Full textAbstract:
碩士弘光科技大學
食品科技所
103
Urinary tract infections (UTI) are the most common infectious diseases in humans and can be nosocomial infections. In the USA, 40–50% of women and 5% of men develop UTIs, which account for more than 1 million hospitalizations and $1.6 billion in medical expenses each year. Uropathogenic Escherichia coli (UPEC), is the primary pathogen of bacterial UTIs, causing >80% of UTIs. In this study, we screened lactic acid bacteria (LAB) strains with antimicrobial effects on UPEC using a well-diffusion assay, bacterial adherence to the uroepithelium cell line SV-HUC-1 (BCRC 60358), and a co-culture inhibition assay. The results showed that a total of 21 LAB strains had more than a tertiary inhibitory ability (inhibition zone diameter ≥23 mm) against UPEC. Six products showed inhibitory ability. In particular, there was a bigger inhibition zone against UPEC by the antimicrobial products LP142, YiShengMi , YiShengMi + ShuMiChang, and ShuMiChang. In the adhesion assay, 7LAB strains (PM2, PM68, PM78, PM201, PM206, PM229, RY2) exhibited stronger adherence to the uroepithelium cell line. These 7 strains were identified as Lactobacillus paracasei, Pediococcus pentosaceus, L. salivarius, P. pentosaceus, L. plantarum, L. plantarum, and L. crispatus, respectively, using the API 50 CHL kit. In acid tolerance and bile salts tests, the results showed that all strains tolerated acidity and bile salts except for PM68 and PM78. Using the co-culture method, the growth of 3 UPEC strains was visibly inhibited in the presence of these strains after 4 h. Growths of the UPEC strains that survived (BCRC10675, BCRC15479 and BCRC 15585) were almost completely inhibited by the 7 LAB strains. In co-culture with urine, the UPEC strains were almost completely inhibited by the LAB strains after 4 h and were completely inhibited by the antimicrobial products in 2 h. In competitive exclusion test, seven lactic acid bacteria strains significantly produce an inhibition E. coli BCRC10675 from uroepithelial cells, and the complex products YiShengMi + ShuMiChang has the strongest inhibitory effects. ELISA results showed LAB and products decreased the levels of IL-6 significantly which induced by E. coli BCRC10675. PM201 increased the levels of IL-8 compared with control (resting) cell. PM2, PM78, PM206, PM229, RY2, YiShengMi, YiShengMi+ShuMiChang significantly decreased the release of IL-8, and the YiShengMi+ShuMiChang has strong inhibitory effects. Cell membrane integrity was determined by the release of lactic acid dehydrogenase (LDH). All of the LAB strains except for RY2 were effective against cell injury induced by UPEC. Finally, we evaluated the protective effect of the LAB products against UTIs caused by UPEC in a BALB/c mouse animal model. Oral administration with PP366, YiShengMi, and ShuMiChang products reduced the viable count of UPEC in the urine of mice; however, the difference was not statistically significant. The group that received YiShengMi + ShuMiChang had a significantly reduced viable count of UPEC in the urine of mice. Therefore, in in vivo test, UTIs can be prevented or improved by YiShengMi + ShuMiChang. The activity of myeloperoxidase (MPO) in urine was determined, and although PP365, YiShengMi + ShuMiChang, and ShuMiChang decreased MPO activity, these differences were not significant. Therefore, this study development of probiotic products might have preventing or ameliorating urinary tract infections function.
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Wu, Sheng-Yen, and 吳昇晏. "Studies on the antagonistic characteristics of endophytic bacteria from banana against Fusarium oxysporum f. sp. cubense race 4." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/95498264656947310063.
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碩士國立中興大學
土壤環境科學系所
99
Endophytic bacteria reside within plant hosts without having pathogenic effects, and various endophytes have been found to functionally benefit plant pathogen supperssive ability. For this reason, in this study, endophytic bacteria which were isolated from banana (Musa spp. cv. ‘Pei Chiao’, AAA group) roots were tested to use a series of in vitro antagonistic activity assay with Fusarium oxysporum f. sp. cubense race 4 (FOC race 4). Moreover, the effect of the change of endophytic bacterial communities in banana roots to Fusarium wilt pathogen infection were analysed by DGGE on the basis of 16S rDNA sequence. The result demonstrated that 11 species endophytic bacteria were identified as Bacillus altitudinis, Bacillus barbaricus, Bacillus mycoides, Bacillus stratosphericus, Burkholderia anthina, Pseudomonas mendocina, Serratia nematodiphila, Rhizobium miluonense, Rhizobium multihospitium, Rhizobium radiobacter, and Rhodococcus triatomae, respectively. Among these isolated, only the bei-1-7 belong to Burkholderia anthina had ever to report in the reference that it was existing in banana roots; others were found in first. The bei-1-7 had the most antifungal activity against FOC race 4 with 98%, and the influence of this inhibitor that secreted from this bacterium also had a level of prevention efficacy when sterilized. In Burkholderia genus, if bacteria species belong to the flora of B. anthina、B. arboris、B. cenocepacia、B. latens、B. metallica、B. seminalis, and B. vietnamiensis that their 16S rDNA had more closely comparability, and its ability of against FOC race 4 had more remarkably. In pots assay, using root-cutting and soaking methods could make the bei-1-7 into the banana roots, but adding the FOC race 4 could not cause the change of endophytic bacteria communities in these plant that they were inoculating in mixed endophytic bacteria or bei-1-7.
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Balasubramanyam, B. V. "Studies on the application of antagonistic lactic acid bacteria in the biopreservation of selected indigenous milk and cereal / pulse based foods." Thesis, 1995. http://hdl.handle.net/2009/1774.
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Lin, Pai-Pai, and 林佩佩. "Antagonistic activity against enterotoxigenic Escherichia coli and enteroaggregative Escherichia coli infection in vitro for lactic acid bacteria strains from healthy infant stool." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/cs2sy3.
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碩士靜宜大學
食品營養研究所
94
Enterotoxigenic Escherichia coli (ETEC) and Enteroaggregative E. coli (EAggEC) is a major cause of sporadic diarrhea disease in humans, affecting mainly children in developing countries and travelers from industrialized countries visiting tropical or subtropical areas. Probiotics have been shown to be inhibitory to the growth of a wide range of intestinal pathogens in human and animals. They are also able to promote the growth of animals. The possible mechanisms might include the production of acids and other by-products of the bacterial metabolism. In this study, we screen the adhesive strains of lactic acid bacteria (LAB) isolated from infant stool. Antagonistic activity was evaluated by inoculating wells among agar cultures of ETEC or EAggEC to assess zones of inhibition created by the lactobacilli cultures or spent culture supernant (SCS). Only a few isolates having high adhesive properties also possessed antagonistic activity. Identification of the isolates using API 50CHL strips showed that they belonged to different species of Lactobacillus. The objective of this study was to determine if adhesive LAB strains can exert inhibitory action on ETEC or EAggEC. Strains of Lactobacillus acdophilus RY2, Lactobacillus salivarius MM1 and Lactobacillus paracasei En4 were used in this study, based on their acid- and bile-tolerance. L. lactis RY2 and L. paracasei En4 could adhere to the cultured human intestinal C2BBel (Caco-2) cell line. After heating (100℃, 15 min), the SCS still had inhibitory effect on ETEC or EAggEC. The SCS were treated with lactate dehydrogenase, amylase, trypsin, chymotrypsin, pepsin, pronase, proteinase K or catalase, respectively. The treatment of lactate dehydrogenase reduce the inhibitory effect of SCS. The antagonistic activity reduced when the pH of SCS was adjusted to neutral (pH 7.2). Antimicrobial activity was performed by incubating the LAB-SCS with ETEC or EAggEC suspension. After 1 hour co-culture, the growth of ETEC and EAggEC was inhibited. The LAB was used as starter in skim milk fermentation. The fermented milk was stored at 4℃. There are 107 CFU/mL of LAB strains RY2 and MM1 after 14 days storage. The population of strain En4 reduced to 106 CFU/mL. This study suggests that L. acdophilus RY2, L. salivarius MM1 and L. paracasei En4 could be used as an effective control of ETEC or EAggEC on fermented milk processing.
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Miller, Eric Louis. "Evolution of microbial populations with spatial and environmental structure." Thesis, 2010. http://hdl.handle.net/2152/ETD-UT-2010-05-1018.
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Rarely are natural conditions constant, but generally biologists study microbes in artificially constant environments in the laboratory. I relaxed these assumptions of constant environments through time and space as I investigated how microbial populations evolve. First, I examined how bacteriophage evolved in the presence of permissive and nonpermissive hosts. I found that bacteriophage evolved discrimina- tion in mixed environments as well as in one of two environments with homogeneous, permissive hosts. This showed the asymmetry of host-shifting in viruses as well as the possibility of large, and somewhat unpredictable, pleiotropic effects. Secondly, I reconstructed ancestral environmental conditions for soil bacteria groups using phy- logenetics and environmental variables of extant species’ habitats. These generaliza- tions suggested characteristic phenotypes for several phylogenetic groups, including uncultured Acidobacteria. Lastly, I collected genetic sequences and global collection information for 65 bacteria genera across the domain. In examining the relation- ship between genetic distance, environmental conditions, and geography, I observed positive relationships specifically between genetic distance and geography or genetic distance and environmental conditions for bacteria from land sites but not from wa- ter sites. Phylogenic classifications or phenotypes of the genera could not predict these correlations. In all of these projects, variations in the environment created evolutionary signals that hinted at past environments of microbial populations.text
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Chiu, Yen-Shin, and 邱燕欣. "Control of citrus bacterial canker by antagonistic Bacillus subtilis WG6-14." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/46266733272422201238.
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碩士國立中興大學
植物病理學系
92
Control of citrus bacterial canker by antagonistic Bacillus subtilis WG6-14 Abstract Yen-Shin Chiu The major objective of this investigation was to explore the antagonistic Bacillus resources as microbial fungicide for the control of citrus bacterial canker (CBC) disease-the most notorious bacterial disease on citrus in Taiwan and worldwide. The development of biofungicide effective for the control of CBC is in urgent need in Taiwan because the disease was devastative and the effectiveness of chemical control agent (mainly copper) was limited. In a screening trial for antagonistic Bacillus resources with application potential in plant disease control, the unusual antagonisity of Bacillus subtilis group (BSG, Priest, 1993.）against wide spectrum of plant pathogenic Xanthomonads was observed. By a pilot scale liquid fermentor system, technique platform for the production of BSG endospore formulation was established. The broth cultures obtained from the trial production have been shown effective in discouraging the infection caused by Xanthomonads; successful examples include bacterial black spot of mango (Xanthomonas campestris pv. manigiferaeindicae, Chou et al., 1997), bacterial spot of tomato (X. axonopodis pv. vesicatoria, Lee, 2002) and bacterial leaf blight of rice (X. oryzae pv. oryzae, Wang, 2002). To explore the use of BSG resources in the control of CBC in Taiwan, a total of 7 BSG strains known with superior antagonisity against wide spectrum of phytopathogenic fungi and bacteria were screened for the competence of endospore production and discouragement of CBC infection. Among them, strain WG6-14 was shown the best in endospore productivity. A followed greenhouse trial where that a multiple-pin artificial inoculation system was applied for quantitative assay of typical CBC infection, further demonstrated that strain WG6-14 was also among them the best in counteracting the infection by X. axonopodis pv. citri Xac01-a typical pathotype A strain of Xac which appeared to be prevalent all over the island. On the tested Navel orange (Citrus sinensis), the pretreatment by foliar spray a 100X diluted WG6-14 endospore formulation (2×109 endospores/ml) 24 hours before artificial inoculation of Xac01 (3.2×106 cfu/ml) resulted in 94% inhibition of the disease incidence. The disease incidence of the compared control which was pretreated by water spray was 97.7%. By greenhouse trial, the efficacy of disease control by WG6-14 was further shown to be dose dependent and the performance was apparently better as pre-inoculation treatment rather than post-inoculation treatment. The disease control efficacy appeared to persist in the case wherein inoculation concentration of Xac01 used for challenge inoculation was raised to 107cfu/ml. It was worth to mention that with the raised challenge inoculation pressure, the disease control efficacy by WG6-14 may exceed that by Bordeaux mixture (BM) application. On the foliar tissue, the antagonist (WG6-14) population showed a fluctuating increase dynamics about 7days. A slow decline of the population might be observed about 10 days after application. With the use of a rifampicin resistant mutant strain Xac01r, the interaction of antagonist (WG6-14) and pathogen (Xac01r) population in relating to CBC symptom development was examined. The virulence of the mutant strain appeared to be the same as the wild type strain Xac01 in that typical protruding necrotic CBC lesion developed within one week after artificial inoculation. Without pretreatment of WG6-14, a steady and rapid increase of Xac01r population was detected on the foliar tissue at the 1st day after the inoculation. In 10 days, the pathogen population increased by approximately 4 orders. And accompanied to that was the development of typical CBC symptoms which became prominent at 4th day after inoculation. Whereas with the pretreatment foliar application of WG6-14, the increase of challenge inoculated pathogen population was suppressed. And the development of CBC symptom appeared not detectable until 5-10 days after inoculation. It was worth noting that the suppression of the pathogen population and the associated symptom expression were apparently the function of the dosage of WG6-14 applied. The suppressiveness of WG6-14 on the pathogen population on the foliar tissue were further demonstrated in a field trial where that Xac01 in stead of Xac01r was applied for challenge inoculation. In field trial performed, the pretreatment of WG6-14 led to a substantial decrease of the afterward applied Xac01 population by more than 1 order at 14th day after inoculation, although the increase of the Xac01 was observed later on. The deteriorative effect in the pathogen population, however, was not observed in BM pretreated plants. The population density of Xac01 on BM pretreated plants remained at the same level as that of water treated control plants. The results discussed clearly indicated the developed endospore formulation of B. subtilis WG6-14 a useful microbial fungicide for the control of CBC on citrus. The effectiveness of disease control was apparently a function of the antagonisity of WG6-14 and its competition in available space and nutrient on the foliar tissue. During the course of the study, prominent growth promotion was consistently observed among plants pretreated with WG6-14.The growth promotion was manifested by the substantially increased new shoot development, canopy size and growth vigor. By a closed container system, we found that certain volatile metabolites produced by WG6-14 were stimulative to seed germination and seedling growth of cabbage (Brassica oleracea L. co. capitata). The bio-fumigation effect on growth promotion and seed germination appeared to work for cabbage, rice, muskmelon, cucumber, watermelon and tomato. The production of the growth promotive volatile metabolite was a function of the bacterial growth and medium used to culture the bacteria. By Voges-Proskauer test, the production of butanediol (approximately 0.0206μg/ml culture broth) was detected from the endospore formulation of WG6-14. Whether or not it may contribute to the growth promotive effect observed on citrus worth great attention.
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Buonpane, Rebecca Ann. "Engineering soluble, high affinity receptor antagonists for bacterial exotoxins /." 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3250214.
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Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2006.Source: Dissertation Abstracts International, Volume: 68-02, Section: B, page: 0874. Adviser: David M. Kranz. Includes bibliographical references (leaves 184-206) Available on microfilm from Pro Quest Information and Learning.
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Zhang, Yilan. "Biocontrol of sclerotinia stem rot of canola by bacterial antagonists and study of biocontrol mechanisms involved." Thesis, 2005. http://hdl.handle.net/1993/121.
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Wang, Shih-Wen, and 王詩雯. "Control of rice bacterial blight by antagonistic Bacillus spp. - the potential application and the mode of action." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/75590702204773125557.
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碩士國立中興大學
植物病理學系
90
Bacterial leaf blight caused by Xanthomonas oryzae pv. oryzae (Xoo) has recently become one of the most devastating diseases of rice cultivated in Taiwan and in most of Asian rice growing countries. Because the lack of effective chemicals, the disease management depend greatly upon the use of resistance cultivars. Unfortunately, the performance of disease resistance is quite often unsatisfactory due to the fast evolution of pathogen traits and/or the unsuitable environmental conditions. Measurement for effective disease control is urgently in need, and biological control appears to be the best among the known alternative strategies. The main objectives of this investigation were to explore the potential of antagonistic bacilli native in Taiwan for the control of leaf blight on rice, and to learn the possibly involved mechanism. A total of 8 Bacillus spp. isolates, putatively chosen from 375 antagonistic bacilli isolate collection based on the understanding of their superior performance in antagonisity against wide spectrum of fungal and bacterial pathogens and good growth and sporulation characteristic, were screened for their competence in leaf blight control. By dual culture assay, all these isolates showed strong antagonisity against the targeted Xoo isolate XF13. And on greenhouse grown paddy rice, all of them survived well on the foliar tissue up to 20 days after spray application. The disease control efficacy was evaluated by greenhouse test in which culture broths of each test bacterium were applied to leaves of TK8 cultivar rice simultaneously with Xoo isolate XF13 by clip inoculation. Among the 8 isolates tested, 5 appeared to be effective in counteracting the infection by XF13. And among the 5, isolates TKS1-1 and WG6-14 consistently performed the best and were thus used for continued disease control screening trials. By shaking culture, the two isolates both appeared to grow well in SYM broth medium; the yield of endospore achieved 2.1 X 109 cfu/ml 5 days after inoculation and in parallel to that was the increase of the antagonisity. The antagonistic activity was significantly enhanced by supplementation of citrulline, ornithine, and histidine. The efficacy of leaf blight control of both isolates was demonstrated by a greenhouse test by the clip-inoculation described. The application of both isolates successfully controlled the leaf blight infection on TK8, TN 67, TCS 10, and TN 1 rice; the efficacy was manifestated by the significantly reduced disease severity and percent infection. Similar results were later obtained in a field trial conducted in Yun-Li, Miao-Li, indicating both isolates are of great value as regard to biological control of the bacterial leaf blight. The efficacy appeared be concentration dependent; satisfactory control efficacy was consistently observed in 10 to 100X diluted WG6-14 treated plants comparing to that treated by 1000X diluted sample. The disease control efficacy appeared to due mainly to the complete inhibition by the applied antagonist on the propagation of Xoo on the clipping wounds. In 1000X diluted WG6-14 treated plants, although the propagation of Xoo was significantly reduced at the early phase of infection, its propagule number was later increased at 5th day after inoculation to the level comparable to that of water treated control plants. The observed inhibitory effect on Xoo was apparently a combined function of applied WG6-14 propagules (endospores primarily) and the accumulated metabolites in the broth culture. The application of WG6-14 bacteria per se and the culture filtrate-each respectively obtained by centrifugation separation of the culture broth, were both less effective in inhibiting Xoo infection as comparing to that by the whole broth culture. By submerging treatment of the cutting wounds with a 10 X diluted WG6-14 culture broth, effective control of Xoo infection was succeeded even with the submerging treatment performed 3 days before or after the Xoo inoculation. It was also noted that the effectiveness of disease control by WG6-14 was prominent even by drenching application. On TK8 rice grown in greenhouse, drenching application of WG6-14 culture broth at 500X and 1000X in dilution reduced the disease severity approximately 37% as comparing to that of water treated control. Although more extensive field trial are needed in order to conclude the disease control efficacy observed, the data presented clearly demonstrated the great potential of WG6-14 and TKS1-1 as biofungicide for the management of bacterial leaf blight of rice. In order to learn whether or not the observed disease control efficacy may be connected to induction of disease resistance, partial sequence of PAL (phenylalanine ammonia lyase) and PR-1 (pathogenesis related protein) genes were cloned by PCR amplification from TK8 rice and used as the molecular tool for monitoring the expression of these resistance pertained genes. Analysis by northern hybridization has detected a transient increase of PAL gene in foliar tissue 3-4 days after spray application with WG6-14 at 100X in dilution. Whether or not this suggests the enhancement of phenylpropanoid pathway in observed disease control efficacy remains to be elucidated.
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Huang, Ru-Yin, and 黃儒音. "Transposon mutagenesis of antagonistic bacterium Bacillus cereus C1L and the cloning of genes related to antifungal activity." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/32323943802353866981.
Full textAbstract:
碩士臺灣大學
植物病理與微生物學研究所
96
Bacillus cereus C1L, an antagonistic bacterium, was originally isolated from the rhizosphere of Fomorsa lily. In order to identify the genes related to the antagonistic ability of B. cereus C1L, a transponson insertion mutant library was constructed. Totally, 850 mutants were obtained. Alternaria brassicicola and Alternaria longipes were used in mutant screening on potato dextrose agar and a mutant, M-902, with significant decrease on antifungal activity was selected. M-902 loses its inhibitory activity against mycelial growth of A. brassicicola, A. longipes, Botrytis cinerea, and Botrytis elliptica ; in addition, the culture supernatant of M-902 decreases spore germination rate. Sequence analysis revealed that the Tn917ac1 was inserted into a plasmid pC1L8 of B. cereus C1L wild-type strain. Southern blot analysis showed a band shift of pC1L8 of B. cereus M-902. The Tn917ac1 insertion site was located downstream a putative promoter of open reading frames-orf1 and orf2。These two ORFs may constitute a two-gene operon. In a complementay test using A. brassicicola as the test fungus, the vector containing predicted promoter, orf1 and orf2, or orf2 singly showed a partial recovery of the inhibition on conidial germination, but orf1 singly could not recover the inhibition on conidial germination. Thus, orf 2 related to antibiotic production of strain C1L was presumed.
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Wu, Yu-Sheng, and 吳昱陞. "Development of Antagonistic Streptomyces sp. S2 for Controlling Bacterial Leaf Spot Disease of Crucifers Caused by Xanthomonas campestris pv. raphani." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/7k2sy3.
Full textAbstract:
碩士國立中興大學
植物病理學系所
106
Bacterial leaf spot disease of crucifers is caused by Xanthomonas campestris pv. raphani (Xcr). In recent years, it has been reported on crucifers, solanaceous crops, and cucurbits in many countries. In this study, we had found and collected diseased cabbage seedlings from the nursery. According to the results of re-inoculation, 16S-23S rRNA spacer sequence analysis, and detection of Xanthomonas campestris pathovars, the isolates from diseased seedlings were identified as Xanthomonas campestris pv. campestris (Xcc) and Xcr. To develop potential biocontrol agents, screening antagonistic Streptomyces species against with Xcr, other bacterial and fungal pathogens had done by dual culture. Streptomyces sp. S2 was selected as a broad-spectrum antagonist against with tested bacteria, oomycetes, ascomycetes and basidiomycetes. It’s important that potential biocontrol agents have to be harmless for plants and humans. Therefore, Streptomyces sp. S2 was identified by 16S rRNA gene sequence analysis and S2 showed 99.8% 16S rDNA sequence identity to that of S. andamanensis strain KC-112 which appeared to be phylogenetically distinct from scab-causing strains. Furthermore, pathogenicity factors such as thaxtomin synthetase A (txtA), necrotic protein (nec1), and tomatinase (tomA) had not detected in S2 genome by using specific primers TxtA1/TxtA2, Nf/Nr, and Tom3/Tom4 respectively. In addition, S2 cultured broth was analyzed for thaxtomin A by using LC/MS/MS and seedling assay. As a result, S2 didn’t produce thaxtomin A, and no phytotoxicity symptom was observed on the cabbage and radish seedlings treated with S2 cultured broth. In brief, Streptomyces sp. S2 as a potential biocontrol agent is safety for application. To control bacterial leaf spot disease effectively, culture condition of S2 had established. The characteristic of S2 grown on ISP medium were analyzed, in consequence, the growth and sporulation of S2 was best on ISP2 medium. Following utilization of carbon and nitrogen source analysis, S2 has good utilization of glucose, xylose, maltose and lactose, poor utilization of sucrose, and no utilization of starch among materials commonly used to fermentation. All of nitrogen sources tested could be utilized well by S2, but sodium nitrate. Furthermore, the effect on replacement of glucose in ISP2 medium with different carbohydrates was evaluated. The sporulation of S2 in submerged ISP2 medium modified by replacing glucose with maltose (mISP2) could be observed under microscopy. Based on mISP2 medium, different concentration of maltose in mISP2, different ratio of yeast extract to malt extract, different concentration of calcium and phosphate buffer, and initial pH value were evaluated. The result so far, mISP2 medium has been the best recipe for sporulation of S2 in submerged culture with initial pH 6.0-7.0; it was negative effect on growth and sporulation when the amount of calcium ion more than 100 ppm and phosphate buffer more than 0.005M in mISP2. To confirm the spores produced in submerged mISP2 were mature and intact, spores collected from submerged culture were compared with spores from agar plates by using electron transmission microscopy. The thick spore cell wall and nozzles could be observed in solid and submerged culture. Finally, 5-dsy mISP2 cultured broth of S2 was used to control disease caused by Xcr on cabbage seeds and leaf. The disease incidence of contaminated seeds(105 CFU/ml) was significantly reduced by treating with the 10×-diluted S2 cultured broth. As well as, the disease severity of cabbage leaves inoculated with Xcr(106 CFU/ml) was significantly reduced by spreading the 100×-diluted S2 cultured broth on leaf surface. In addition, S2 cultured broth could be mixed with bactericide oxolinic acid 100 ppm without negative effect on disease control. In conclusion, Streptomyces sp. S2 is a safe and broad-spectrum antagonist against phytopathogens. Streptomyces sp. S2 grew well and formed spores in mISP2 submerged culture. In greenhouse trial, bacterial leaf spot disease was significantly controlled by S2 cultured broth. Low sensitivity to several bactericides. S2 as a potential strain that is ready to process scale-up production and apply for integrated pest management.
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"Análise transcricional do fitopatógeno Fusarium graminearum Schwabe na interação antagonista com a bactéria Pantoea agglomerans Gavini." Tese, Biblioteca Digital de Teses e Dissertações da USP, 2006. http://www.teses.usp.br/teses/disponiveis/64/64133/tde-04052007-085012/.
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