Academic literature on the topic 'Bactera'
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Journal articles on the topic "Bactera"
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Yadav, Amresh Kumar, Sanjeev Kumar Ambasta, Surendra Kumar Prasad, and M. P. Trivedi. "IN VITRO EVALUATION OF ANTIBACTERIAL PROPERTY OF CATHARANTHUS ROSEUS (LINN.) G. DON. VAR. “ROSEA” AND “ALBA”." International Journal of Pharmacy and Pharmaceutical Sciences 10, no. 5 (2018): 55. http://dx.doi.org/10.22159/ijpps.2018v10i5.24977.
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Objective: To evaluate the antibacterial property of crude, aqueous and organic solvent extract from leaf, stem and root parts of two different var. of Catharanthus roseus (i.e. “rosea” and “alba”) under in vitro conditions on various human pathogenic bacteria.Methods: Antibacterial activity of crude (fresh), aqueous, ethanolic, methanolic and equimolar (1:1) mixture of ethanolic dried leaf extract of variety “rosea” and “alba” was evaluated against various pathogenic bacteria viz. Bacillus subtilis, Escherichia coli and Staphylococcus aureus by disk diffusion method under in vitro conditions.Results: Gram-positive bacteria were found to be more susceptible than Gram-negative. Dried extracts of root, stem and leaf of C. roseus var. “rosea” and “alba” plants showed maximum antibacterial potency against all the test microorganisms. The equimolar mixture of ethanolic dried leaf extracts of species “rosea” and “alba” exhibited the maximum zone of inhibition against B. subtilis, E. coli and S. aureus as compare to extract prepared from individual parts. The findings of the ethanolic mixture of dried leaves of the two varieties on the tested bactera confirm that the effect is potentiating which may be synergistic or additive.Conclusion: From the findings, it could be inferred that C. roseus var. “rosea” and “alba” could be efficiently used in the development of new life-saving drugs against bacterial pathogens.
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Kim, Dong-Seon, Joo-Hwan Roh, Chang-Won Cho, and Jin-Yeul Ma. "Analysis of Nodakenetin from Samultangs Fermented by Lactose Bactera Strains." Korea Journal of Herbology 27, no. 1 (2012): 35–39. http://dx.doi.org/10.6116/kjh.2012.27.1.35.
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Grabowska-Markowska, Jolanta, Iwona Pawłowska, Grzegorz Ziółkowski, and Jadwiga Wójkowska-Mach. "BACTERIA CAUSED BY OCHROBACTRUM ANTHROPI – UNUSUAL BEHAVIOR." Wiadomości Lekarskie 72, no. 3 (2019): 489–92. http://dx.doi.org/10.36740/wlek201903131.
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O. anthropi, formerly known as Achromobacter, is an aerobic, Gram-negative bacillus, widespread in the environment, in various ecological niches. Currently, it is an emerging opportunistic microorganism associated with health care, as well as infections in people with immunodeficiency, mainly in children and newborns. The authors of the presented work present a case of a 13-year-old female patient with a neurodegenerative disorder in which O. anthropi was isolated from blood cultures. She was hospitalized in the Social Society of the Cordis Hospice in Katowice, and after discharge from the hospice she was covered by long-term home care under the supervision of a family doctor. Clinical picture O. anthropi can be very different, causes serious infections, such as blood infections. Due to difficulties in identification, Ochrobactrum anthropi can be a diagnostic and therapeutic challenge. The difficulty in differentiating Ochrobactrum spp. Is also related to the lack of a clear clinical picture of infection with bactera O.anthropi. In addition, this microorganism is difficult to treat due to the natural broad spectrum of antibiotic resistance.
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NAKAGAWA, Masaya, and Norihiko MISAWA. "Analysis of Carotenoid Glycosides Produced in Gram-negative Bactera by Introduction of the Erwinia uredovora Carotenoid Biosynthesis Genes." Agricultural and Biological Chemistry 55, no. 8 (1991): 2147–48. http://dx.doi.org/10.1271/bbb1961.55.2147.
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Jin, Tianru, and R. G. E. Murray. "Urease activity related to the growth and differentiation of swarmer cells of Proteus mirabilis." Canadian Journal of Microbiology 33, no. 4 (1987): 300–303. http://dx.doi.org/10.1139/m87-051.
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Urease activity was measured using whole cells of both long (swarming) and short (nonswarming) populations of Proteus mirabilis from casein hydrolysate agar (CHA) and broth (CHB) cultures, and from brain heart infusion broth (BHIB) cultures. Urease is a constitutive enzyme for both long and short cells, but its activity was tremendously increased when urea was incorporated into the media. Urease production was also affected by culture age and media used. Before exponential phase, urease activity was very low, and it increased to its highest point after about 4 h in BHIB and 8 h in both CHA and CHB cultures at 37 °C. Long cells had higher urease activity than did short cells when grown on CHA, and was also expressed by two different strains cultured in BHIB. Strain PM23, in BHIB, was able to form long cells (swarming cells) to a maximum proportion after about 4 h, but strain IM47 could not differentiate in any of the liquid media. The former had more urease when swarming differentiation was initiated. PM23 grew relatively faster than IM47 when the former began to differentiate, but this fast growth could not be observed when nutrient broth or minimal medium was used. These observations suggest that long or swarming cells are "faster growing" rather than "nongrowing bactera."
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Oktanauli, Poetry. "The Effect of Herbal Mouthwash against Halitosis in Elderly." Jurnal Ilmiah dan Teknologi Kedokteran Gigi 16, no. 1 (2020): 25. http://dx.doi.org/10.32509/jitekgi.v16i1.611.
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Introduction: Elderly generally experience a decreased in the level of oral hygiene, number of teeth, mucosal sensitivity of the oral cavity and xerostomia. Xerostomia can cause halitosis. One of halitosis therapy is by using herbal mouthwash (betel leaf). Betel leaf has an antibacterial, antioxidant and antifungal ability. The purpose of this study was to provide information on the benefits of herbal mouthwash on decreasing halitosis score in elderly. Methods: This was a clinical experimental research with cross sectional approach. Spearman correlation test was used to determine the effect of herbal mouthwash on decreasing halitosis scores. The numbers of subject were 30 and obtained by quota sampling. Data collection was done by measuring initial and final halitosis score after rinsing with herbal mouthwash, using Tanita breath checker. Tanita breath checker is an innovative palm-sized monitor that can detect and measure the presence of volatile sulfur compound (VSC) by displaying 6 levels of halitosis. Results: The result showed a decrease in halitosis score before and after rinsing with herbal mouthwash (betel leaf). A significant decrease in the halitosis score is indicated by the p=0,000 obtained from the results of the Spearman correlation test. There was a significant decrease in the halitosis score after rinsing with herbal mouthwash. Conclusion: The present study showed that the decrease in halitosis score is due to the betel leaf containing essential oils. The main component of essential oils consists of phenols and their derivative compounds, namely kavikol. Thus, betel leaf was able to fight gram-positive and gram-negative bactera, so that it can be used to treat halitosis in elderly.
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Tovkach, F. I., and G. I. Zhuminska. "Destabilization of the Phage-Bacteria System during Bacterial Infections of Tree Plants." Mikrobiolohichnyi Zhurnal 81, no. 4 (2019): 118–30. http://dx.doi.org/10.15407/microbiolj81.04.118.
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Ali, Zainab Haider, Wurood Hamzah Muttaleb, and Lubna Abdulazeem. "Anti-Bacterial Action of Silver Nanoparticles Against MDR Bacteria Isolated from Hospital." International Journal of Medical Science and Dental Health 10, no. 10 (2024): 93–99. http://dx.doi.org/10.55640/ijmsdh-10-10-11.
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Hospital-associated infections (HAIs) are considered to be a major source of infections in patients, especially in patients with permanently impaired immunity. There is alarming increase of multi drug resistant (MDR) bacteria and Antibacterial medication resistance has been deemed a serious hazard to public health by the World Health Organisation (WHO). The study aimed to isolate and identify main bacteria caused nosocomial infection, and trying to treatments by using nanoparticles. By measuring the antibacterial activity of the synthesised AgNPs using the agar disc diffusion technique, AgNPs demonstrated antibacterial properties against the Pseudomonas aeruginosa and Staphylococcus aureus MDR.
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Danylenko, S. G., O. V. Naumenko, A. S. Onishchenko, S. M. Teterina, M. O. Khonkiv, and S. O. Skrotskyi. "Biotechnology of Newly Created Bacterial Composition for Siloing Based on Lactic Acid Bacteria." Mikrobiolohichnyi Zhurnal 83, no. 6 (2021): 20–31. http://dx.doi.org/10.15407/microbiolj83.06.020.
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Peculiarities of high-quality silage production are the use of biological products based on lactic acid bacteria. The composition of such starters varies greatly according to the use of bacterial cultures, so among the starters available on the market, the range of their effectiveness is also different. It is very common to use a one-sided approach to the choice of bacterial components, which in combination with imperfect production technology have low preservative activity. The study of combined preparations, which combine homo- and heterofermentative types of lactic acid fermentation, allows to stabilize the preservative properties throughout the ensiling time, and increase the aerobic stability of the silage after access of oxygen. Aim. Development of biotechnology of bacterial preparation for corn ensiling, optimization of cultivation conditions of newly created bacterial composition, and selection of cryoprotectants for its lyophilization. Methods. The combined preparation was created on the basis of heterofermentative strain Lactobacillus buchneri 3806 combining it in two- and three-strain compositions with other representatives of lactic acid bacteria, which are characterized by obligate homofermentative and facultative heterofermentative types of metabolism. Optimization of the environment and technological parameters was carried out using a central-compositional plan, further statistical analysis of the obtained data and determination of optimal values of input parameters according to the created mathematical model of optical density response. The effectiveness of the selected protective media was tested for the survival of bacteria after lyophilization. Results. The most effective bacterial composition was found during experiments: L. buchneri 3806, Enterococcus faecium C-8-12, L. plantarum 3216. The effectiveness of the obtained composition was tested by laboratory silage of corn. Tests of the drug based on the selected bacterial composition showed an improvement in the chemical composition of the silage compared to the untreated control and treated only with monoculture L. buchneri 3806, namely: there was a decrease in dry matter loss by 2.21% and 2.04%, 22 due to the increase of lactic acid content, and increase of aerobic stability of silage – 341 h against 57 h of the control sample, and 313 h in case of using monoculture. For the obtained bacterial composition, the culture medium of the following composition was optimized: base (hydrolyzed milk with the addition of the following components: monosubstituted potassium phosphate – 2 g/L; 5-aqueous manganese sulfate – 0.05 g/L; 7-aqueous magnesium sulfate – 0.2 g/L; twin-80 – 1.0 g/L); glucose – 19.7 g/L; yeast extract – 7.8 g/L; corn extract – 23.6 g/L; peptone – 9.1 g/L; sodium citrate – 6.6 g/L; sodium acetate – 3,4 g/L. Cultivation of the bacterial composition on an optimized medium made it possible to obtain the maximum biomass yield, at which the optical density was 2.01 units, which is almost twice as much as the value obtained by culturing the same composition in MRS medium. The optimal technological parameters of culturing the bacterial composition were established, namely the best growth was observed at a temperature of 36.4±0.4°C with constant maintenance of the pH value in the culture medium at the level of 6.5±0.1 units. In addition, the optimal composition of the protective medium containing sodium citrate, sucrose and agar was selected, and ensures the survival rate of lactic acid bacteria 98.4% after lyophilization. Conclusions. The newly formed bacterial composition can be used for the production of preparations for corn silage, and tested on other raw materials, in particular on some perennial legumes (alfalfa, clover), and the conditions of its production can be used to scale the technology.
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Aini, Fitratul. "The Effectivity of Bacteria Isolated From of Liquid Waste Palm Oil Plantation on Ganoderma Boninense." International Journal of Ecophysiology 1, no. 1 (2019): 1–7. http://dx.doi.org/10.32734/ijoep.v1i1.841.
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Ganoderma boninense is one of the main pathogenic fungus in oil palm plantations. Generally, these pathogen cause root rot (basal stem rot). Biological control that has been widely used reduce the infection is using bacteria. Liquid waste palm oil has potential to produce bacteria that is able to degrade Ganoderma boninense that causes root rot in oil palm. Liquid waste were obtained from Muaro Sabak Regency Jambi Province. Bacteri were isolated and cultivated in nutrient agar medium, characterized and identified for antagonistic test against G. boninense. Results showed that 16 bacterial isolates were identified, among of them are able to inhibit Ganoderma boninense.
Dissertations / Theses on the topic "Bactera"
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Thomas, Lee. "Genetic methods for Rapid Detection of Medically Important Nosocomial Bactera." Thesis, The University of Sydney, 2007. http://hdl.handle.net/2123/3575.
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The role of the microbiology laboratory is (1) to provide infection control information, so that highly transmissible isolates may be identified and appropriate control measures instigated as rapidly as possible and (2) to provide adequate information to the clinician enabling correct antibiotic choices to be made, particularly in the critically ill. Microbiological data is by definition slow as it is culture dependent: this study focused on the development of genetic, culture-independent methods for detection of resistance in nosocomial pathogens that could be introduced into the routine microbiology department and would fit into the routine workflow with a consequent reduction in time to result. Initially a duplex real-time polymerase chain reaction was developed for the rapid identification and detection of S. aureus and methicillin-resistance. This was optimised for immediate as-needs testing of positive blood cultures signalling with “Gram positive cocci, possibly staphylococcus” evident on Gram stain, on a random access real-time PCR platform. This technology, allowing early identification of S. aureus and its susceptibility to methicillin, by simple automated methodology, may soon become the standard for all microbiology laboratories servicing the critically ill. The second part of the study involved the development of a selective broth and multiplex PCR for detection of three important nosocomial isolates at this institution, methicillin-resistant S. aureus (MRSA), carbapenem-resistant Enterobacteriaceae, and multi-resistant Acinetobacter baumannii (MRAB). A multiplex PCR using four primer sets was designed to detect low colonisation levels of these isolates after overnight incubation in selective broth, significantly reducing the time to result and associated costs. This potentially useful epidemiological screening tool is practical, reproducible and sensitive with the potential of moving to an automated test (using real-time PCR, for example) in the future. The availability of early negative results judged by simple visual scanning (or by densitometry), means that the result is less operator-dependent, potentially reducing error rate. The last part of the study dealt with an important resistance phenotype, aminoglycoside resistance. There had been no recent comprehensive local surveys performed to determine the frequency of aminoglycoside resistance amongst the Enterobacteriaceae, or to identify the genetic determinants and their transmissibility. The isolates collected for the study were all resistant to at least one of gentamicin, tobramycin or amikacin. Identification of integron cassette arrays and use of specific internal primers identified at least one genetic determinant for gentamicin and tobramycin resistance in 22 of 23 isolates. Three isolates had two aminoglycoside resistance genes, and three isolates had three aminoglycoside resistance genes identified (Table 6.1). Transferable gentamicin-resistant plasmids were predominant amongst Klebsiella spp., but less so amongst Enterobacter spp. and E. coli. Gentamicin-resistant Klebsiella spp. were often ESBL positive, the genetic determinants of which were typically co-transferred on a conjugative plasmid. The importance of screening at a local level was demonstrated by the unexpected predominance of aac(6')-IIc amongst Enterobacter spp. and the detection of a new gene (aac(6')-LT). This part of the study has provided an understanding of the primary aminoglycoside resistance genes present in the local setting and their association with other resistances. This knowledge will allow development of assays for patient screening (clinical isolates and colonising flora), to better understand the epidemiology of aminoglycoside resistance and to allow better choice of antibiotic therapy related to presence or absence of these genes.
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Thomas, Lee. "Genetic methods for Rapid Detection of Medically Important Nosocomial Bactera." University of Sydney, 2007. http://hdl.handle.net/2123/3575.
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Master of Science<br>The role of the microbiology laboratory is (1) to provide infection control information, so that highly transmissible isolates may be identified and appropriate control measures instigated as rapidly as possible and (2) to provide adequate information to the clinician enabling correct antibiotic choices to be made, particularly in the critically ill. Microbiological data is by definition slow as it is culture dependent: this study focused on the development of genetic, culture-independent methods for detection of resistance in nosocomial pathogens that could be introduced into the routine microbiology department and would fit into the routine workflow with a consequent reduction in time to result. Initially a duplex real-time polymerase chain reaction was developed for the rapid identification and detection of S. aureus and methicillin-resistance. This was optimised for immediate as-needs testing of positive blood cultures signalling with “Gram positive cocci, possibly staphylococcus” evident on Gram stain, on a random access real-time PCR platform. This technology, allowing early identification of S. aureus and its susceptibility to methicillin, by simple automated methodology, may soon become the standard for all microbiology laboratories servicing the critically ill. The second part of the study involved the development of a selective broth and multiplex PCR for detection of three important nosocomial isolates at this institution, methicillin-resistant S. aureus (MRSA), carbapenem-resistant Enterobacteriaceae, and multi-resistant Acinetobacter baumannii (MRAB). A multiplex PCR using four primer sets was designed to detect low colonisation levels of these isolates after overnight incubation in selective broth, significantly reducing the time to result and associated costs. This potentially useful epidemiological screening tool is practical, reproducible and sensitive with the potential of moving to an automated test (using real-time PCR, for example) in the future. The availability of early negative results judged by simple visual scanning (or by densitometry), means that the result is less operator-dependent, potentially reducing error rate. The last part of the study dealt with an important resistance phenotype, aminoglycoside resistance. There had been no recent comprehensive local surveys performed to determine the frequency of aminoglycoside resistance amongst the Enterobacteriaceae, or to identify the genetic determinants and their transmissibility. The isolates collected for the study were all resistant to at least one of gentamicin, tobramycin or amikacin. Identification of integron cassette arrays and use of specific internal primers identified at least one genetic determinant for gentamicin and tobramycin resistance in 22 of 23 isolates. Three isolates had two aminoglycoside resistance genes, and three isolates had three aminoglycoside resistance genes identified (Table 6.1). Transferable gentamicin-resistant plasmids were predominant amongst Klebsiella spp., but less so amongst Enterobacter spp. and E. coli. Gentamicin-resistant Klebsiella spp. were often ESBL positive, the genetic determinants of which were typically co-transferred on a conjugative plasmid. The importance of screening at a local level was demonstrated by the unexpected predominance of aac(6')-IIc amongst Enterobacter spp. and the detection of a new gene (aac(6')-LT). This part of the study has provided an understanding of the primary aminoglycoside resistance genes present in the local setting and their association with other resistances. This knowledge will allow development of assays for patient screening (clinical isolates and colonising flora), to better understand the epidemiology of aminoglycoside resistance and to allow better choice of antibiotic therapy related to presence or absence of these genes.
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Almeida, Beatriz Silveira Viana de. "Análise do proteoma do fluído intercelular de folhas de laranjeiras infectadas com Xylella fastidiosa." Universidade de São Paulo, 2002. http://www.teses.usp.br/teses/disponiveis/11/11138/tde-24072002-164115/.
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Com o objetivo de compreender os mecanismos que regulam a interação citros-Xf procurou-se identificar e caracterizar proteínas com acúmulo diferencial no apoplasto de folhas de Citrus sinensis var. Pêra infectadas com Xf, apresentando ou não sintomas de CVC, através de eletroforese bidimensional em géis de poliacrilamida desnaturante e espectrometria de massa (MALDI-ToF). O fluído intercelular (FI) foi extraído de folhas de laranjeira cultivadas em campos experimentais. A presença ou ausência do patógeno foi confirmada por amplificação, através de PCR, de fragmentos específicos de DNA da bactéria a partir de DNA total extraído do pecíolo da folha. Para avaliar a complexidade dos proteomas, e a sua variabilidade entre plantas de diferentes localidades, as proteínas foram separadas por eletroforese em géis de poliacrilamida desnaturantes. Os resultados indicam que o proteoma do FI de plantas de localidades diferentes são distintos, independente da presença de Xf e ou sintomas de CVC, e também independe do local onde as amostras foram coletadas. Para a identificação de proteínas com acúmulo diferencial no FI, quantidades iguais de proteínas do FI de folhas dos diferentes tratamentos foram separadas por eletroforese bidimensional em gel de poliacrilamida desnaturante. Proteínas foram com acúmulo diferencial selecionadas para o seqüenciamento da extremidade N-terminal. As proteínas mais abundantes e com aúmulo diferencial nas condições experimentais possuem massa molecular aparente de 41 kDa e pI variando de 4,1 a 5,5. Algumas proteínas de FI de folhas infectadas sem sintomas de CVC, massa molecular de 41kDa , pI 4,2 a 5 apresentaram aumento no acúmulo de proteínas variando de 89 a 129% relação aos FI de folhas de laranjeiras não-infectadas. Suas seqüências Nterminal, e os espectros de massa de seus peptídeos, após digestão com tripsina, são praticamente idênticos, indicando que elas são isoformas da mesma família de proteinas. As seqüências N-terminal dessas proteínas ou dos peptídeos gerados por clivagem com tripsina não apresentam homologia com proteínas/genes nos bancos de dados públicos, sugerindo que essas proteínas são específicas do apoplasto de folhas de laranjeiras e podem ter papel importante na regulação da interação citros-Xf.<br>In order to understand the mechanisms regulating the Xylella fastidiosacitrus (Citrus sinensis var. Pêra) interaction, proteins with differential accumulation in the apoplast of Xf-infected citrus leaves with or without disease symptoms as compared to non-infected leaves, were identified and characterized using 2D-PAGE and mass spectrometry (MALDI-ToF). The intercellular fluid (IF) was extracted by infiltration and centrifugation from field grown leaves segments. The presence of Xf in the leaves was determined by PCR-amplification of specific DNA fragments. SDS-PAGE was performed in a discontinuous system using equal amounts of IF proteins from non-infected and infected leaves with or without CVC symptoms collected from field grow plants at diferrent locations. Protein profiles were compared using discriminant analyses, based on the relative abundance of each protein. The results indicated that the IF proteome of plants from different localities are distinct, independent of the presence of Xf and/or CVC symptoms. Also, independent of the local where the samples were collected, the IF proteome of non-infected leaves and symptomatic infected leaves were distinct. Using 2D-PAGE it was possible to identify proteins with differential accumulation in the IF of symptomatic and asymptomatic Xf infected citrus leaves, as compared to noninfected controls. The must abundant proteins in the IF showing differential accumulation have apparent molecular mass of 41kDa and pI 4,2-5. The accumulation in the IF asymptomatic Xf infected citrus leaves were 89-129% higher than non-infected controls. Their N-terminal position and the mass spectra of their peptides, after trypsin digestion, are mostly identical, indicating that the are isoforms of the same proteins familiy. N-terminal sequences of the proteins and their internal peptides showed no homology to known genes/proteins in public database, suggesting that these proteins are apoplastic citros specifid proteins, and that they may have a important roles in regulating citrus-Xf interactions.
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Bou, habib Michèle. "Développement et analyse d'un modèle dynamique d'attaque de phages lors de l'acidification du lait pour la fabrication du fromage." Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASB061.
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Avec l'augmentation de la demande pour les produits fromagers, l'optimisation des procédés de production est devenue essentielle. L'une des premières étapes de la fabrication du fromage est l'acidification du lait, qui influence fortement les propriétés organoleptiques, la texture et la sécurité du produit final. Elle consiste à convertir le lactose, sucre du lait, en acide lactique par des bactéries lactiques. Cependant, ces bactéries sont sensibles aux attaques de virus appelés bactériophages. Ces attaques peuvent entraîner la lyse bactérienne, retardant ou arrêtant l'acidification, ce qui engendre des pertes économiques dues au rejet du lait et à la nécessité de nettoyer les installations. Cela souligne l'importance d'une meilleure compréhension des interactions phages-bactéries en fromagerie.Une approche novatrice pour étudier ces interactions est la modélisation mécaniste dynamique. Cette étude vise donc à contribuer à une meilleure compréhension des interactions phages-bactéries dans les processus de fermentation du lait en établissant un modèle dynamique.Pour ce faire, nous avons utilisé une méthode de mesure à haut débit du pH pour générer des données sur l'acidification dans différentes conditions initiales de bactéries et de phages. Cette approche nous a permis de distinguer trois résultats distincts en fonction de ces conditions : pour certaines conditions, l'acidification a été une réussite ; pour d'autres, elle a échoué ; et pour le reste, le résultat n'a été ni un échec complet ni une réussite complète.Le modèle mécaniste développé comprend cinq équations différentielles ordinaires (EDO) et prend en compte divers phénomènes, tels que l'inhibition par le produit, le temps de latence, l'adsorption des phages et la lyse cellulaire. Le modèle a donné des résultats satisfaisants, prédisant avec précision les données expérimentales et identifiant correctement le résultat de l'acidification. Nous avons également comparé différentes structures de modèle et effectué une analyse de sensibilité pour révéler les phénomènes dominants, ce qui a aussi aidé à concevoir de nouvelles expériences informatives.Une analyse théorique du modèle a révélé trois phases temporelles de l'attaque : d'abord, la phase de contamination, un court laps de temps où les phages s'adsorbent aux bactéries ; puis la phase de propagation, dominée par la propagation des phages et l'infection des bactéries sensibles ; et enfin, la phase de décharge, caractérisée par la lyse bactérienne et la libération de nouveaux phages. Le temps de transition entre les deux dernières phases, noté t*, a été relié aux conditions initiales. Nous avons également identifié une composante dynamique rapide qui peut être séparée des dynamiques lentes. En utilisant l'approximation de l'état quasi-stationnaire, nous avons établi une relation analytique entre les conditions initiales des bactéries et des phages et le pH final. Cela montre que l'acidification ne dépend pas uniquement du rapport des conditions initiales. Cette approximation a permis de réduire le modèle, économisant 83 % du temps de simulation.Enfin, nous avons développé un outil pour prédire le nombre d'acidifications réussies possibles avant qu'un nettoyage ne soit nécessaire. Les résultats sont basés sur des données faciles à obtenir, comme la quantité de bactéries utilisée et les résultats d'une acidification précédente. Cela représente une première étape vers la conception d'un outil d'aide à la décision pour les fromagers.Cette étude améliore notre compréhension des dynamiques d'attaque des phages lors de l'acidification du lait et permet des prédictions précises grâce à un système d'EDO et un modèle réduit<br>As the demand for diverse cheeses increases, there is a growing interest in optimizing production processes. One of the earliest steps in cheese-making is milk acidification, which highly influences the final product's organoleptic properties, texture, and safety. Milk acidification involves the conversion of lactose, the sugar in milk, into lactic acid by lactic acid bacteria. However, these bacteria are susceptible to attack by viruses known as bacteriophages. This attack can lead to bacterial lysis, resulting in delayed or halted acidification, which incurs significant economic losses as milk is discarded and production facilities require extensive cleaning. This highlights the need for a deeper understanding of phage-bacteria interactions in cheese-making. Research efforts in the dairy industry have primarily focused on characterizing the phages involved and finding new strategies to mitigate phage attacks.One novel approach to studying these interactions is through dynamic mechanistic modeling. Previous models have been developed but have never been applied to the dairy industry. This study aims to fill this gap by contributing to the broader understanding of phage-bacteria interactions in milk fermentation through the establishment of a dynamic model.To achieve this, we first employed a high-throughput pH measurement method to generate acidification data under different initial conditions of bacteria and phages. This methodology proved useful in distinguishing various dynamic behaviors depending on these conditions. It allowed us to delineate three distinct outcomes depending on these conditions: for some conditions the acidification was a success; for some others, it was a failure; and for the rest, the result was neither a complete failure nor a complete success.The mechanistic model we developed consists of five ordinary differential equations (ODEs) and accounts for various phenomena, including product inhibition, lag time, phage adsorption, and cell lysis. The model yielded satisfactory results, accurately predicting experimental data and correctly identifying the acidification outcome. We further investigated the model's structure by comparing various candidate structures and performing a sensitivity analysis to reveal the dominant phenomena throughout the process. The sensitivity analysis also contributed to the design of new informative experimental setups.A theoretical analysis of the model provided insights into the intrinsic dynamics of the system, revealing three time frames of the attack. First, the contamination phase, a short initial time where phages adsorb to the bacteria. Next, the spread phase, where the dominant dynamics involve the spread of phages and the infection of susceptible bacteria. Finally, the discharge phase, where the dominant dynamics are the lysis of bacteria and the release of new phages. The switch time between the last two phases was defined as t∗ and its dependency on the initial conditions was characterized.We also identified a faster dynamic component of the system that can be separated from slower ones. Utilizing the quasi-steady state approximation, we established an analytical relationship between the initial conditions of bacteria and phages and the resulting pH. This relationship indicates that the final outcome of acidification does not solely depend on the ratio of initial conditions but is more complex. The approximation resulted in a reduced model that saved 83% of the simulation time.Finally, we developed a tool to predict the number of potential successful acidifications that can be run before cleaning is required. The results are based on easily obtainable inputs. This represents a first step toward designing a decision aid tool to help cheese makers in their production.This study enhances our understanding of the dynamics of phage attack in milk acidification and facilitates accurate predictions of these dynamics through an ODE system and a reduced model
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Moyà, Anderico Laura. "Deciphering the utility of Galleria mellonella as an infection and toxicity in vivo model." Doctoral thesis, Universitat de Barcelona, 2021. http://hdl.handle.net/10803/671803.
Full textAbstract:
Galleria mellonella (greater wax moth) is a popular animal model that has been extensively used as an alternative in vivo model for investigating the virulence and pathogenicity of different bacteria. G. mellonella has also been shown to be a suitable model for studying the efficacy and toxicity of various compounds. Recently, this model has been gaining popularity as the larvae are conveniently sized for manipulation, they do not need constant feeding, they are inexpensive to purchase and to breed, they do not require much space or special infrastructure, they present a low biohazard risk, and they are more ethically accepted. More importantly, G. mellonella has an innate immune system very similar to the one found in mammals. In this thesis, G. mellonella was used to develop a standardized and reproducible animal model of infection and toxicity.
Pseudomonas aeruginosa is an opportunistic pathogen that has gained great medical importance as it causes serious illnesses in humans and it can be resistant to many antibiotics. During infection, ribonucleotide reductases (RNR) play an essential role as they catalyze the reduction of ribonucleotides to deoxyribonucleotides, thus providing the precursor molecules needed for DNA synthesis. Since G. mellonella has been proven to be a suitable model for P. aeruginosa infections, we developed a promoter probe vector with bioluminescence expression to enhance the study and monitoring of a P. aeruginosa in vivo infection. This vector was used to construct different RNR gene promoter fusions as proof of concept. Additionally, we optimized a total bacterial RNA extraction protocol to facilitate the study of transcriptional gene levels during in vivo infections.
Staphylococcus aureus is also considered an opportunistic pathogen. This bacterium is also capable of forming biofilms and it is considered an important cause of biofilm formation in catheters and prostheses. Due to the misuse and overuse of antimicrobials, multi-resistant bacteria are rapidly appearing so there is a critical need for new antimicrobials. The toxicity and antimicrobial efficacy against S. aureus of novel oleanolic and maslinic acid derivatives were determined using G. mellonella. Out of the 14 derivatives tested, 2 were found to have improved toxicity and efficacy in vivo when compared to the in vitro results.
G. mellonella was also used to test the toxicity of other therapeutical strategies and nanoparticles (NPs). Mycolicibacterium brumae was not toxic to G. mellonella larvae, and the results correlated with the results obtained with mice. The different NPs caused a variety of acute toxicity effects that were detected by an array of indicators within the larvae, such as lethal dose calculation, hemocyte proliferation, NP distribution, behavioral changes, and histological alterations. Due to the broad applicability of the G. mellonella model, new methodologies are warranted to exploit its full potential. Besides the optimized RNA extraction protocol already mentioned, an optical clearing protocol was also optimized in this work. As a proof of concept for our larvae clearance protocol, fluorescent rhodamine NPs were injected into larvae that were then fixed with paraformaldehyde, permeabilized with increasing concentrations of methanol, and cleared with BABB (Benzyl Alcohol and Benzyl Benzoate).<br>Galleria mellonella es un modelo animal utilizado extensamente como alternativa para investigar la virulencia y patogenicidad bacteriana in vivo. También es apropiado para estudiar la eficacia y toxicidad de compuestos. Las larvas tienen un tamaño manejable, son económicas de adquirir y reproducir, presentan un bajo riesgo biológico, y son más aceptadas
éticamente. Además, tienen un sistema inmunológico innato muy similar al de los mamíferos. Utilizamos G. mellonella para desarrollar un modelo animal de infección y toxicidad estandarizado y reproducible.
Pseudomonas aeruginosa, un patógeno oportunista, que infectando emplea ribonucleótido reductasa (RNR), catalizando la reducción de ribonucleótidos a desoxirribonucleótidos y proporcionando así las moléculas precursoras necesarias para la síntesis de ADN. Desarrollamos un vector sin promotor con bioluminiscencia, el cual se utilizó para construir fusiones con los promotores de los genes RNR. Además, optimizamos un protocolo de extracción de ARN bacteriano para facilitar el estudio de los niveles transcripcionales de genes in vivo.
Debido a la multiresistencia emergente de Staphylococcus aureus, se probó la toxicidad
y eficacia antimicrobiana de nuevos derivados del ácido oleanólico y maslínico en G. mellonella. De los catorce derivados probados, dos tenían menos toxicidad y más eficacia in vivo que in vitro.
G. mellonella se usó para determinar la toxicidad de nanopartículas y estrategias terapéuticas. Mycolicibacterium brumae no fue tóxica para las larvas y los resultados se correlacionaron con los obtenidos con ratones. Las nanopartículas causaron efectos tóxicos en las larvas detectados por la medición de la dosis letal y la proliferación de hemocitos, entre otros indicadores.
Debido a la amplia aplicabilidad de G. mellonella, se necesitan nuevas metodologías para maximizar su potencial. Además del protocolo de extracción de ARN previamente mencionado, también se optimizó otro de aclaramiento. Las larvas fueron inyectadas con nanopartículas, fijadas con paraformaldehído, permeabilizadas con metanol y aclaradas con alcohol bencílico y benzoato de bencilo.
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de, Klerk Nele. "Host-bacteria interactions : Host cell responses and bacterial pathogenesis." Doctoral thesis, Stockholms universitet, Institutionen för molekylär biovetenskap, Wenner-Grens institut, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-126425.
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Helicobacter pylori colonizes the human stomach, where it causes gastritis that may develop into peptic ulcer disease or cancer when left untreated. Neisseria gonorrhoeae colonizes the urogenital tract and causes the sexually transmitted disease gonorrhea. In contrast, Lactobacillus species are part of the human microbiota, which is the resident microbial community, and are considered to be beneficial for health. The first host cell types that bacteria encounter when they enter the body are epithelial cells, which form the border between the inside and the outside, and macrophages, which are immune cells that engulf unwanted material. The focus of this thesis has been the interaction between the host and bacteria, aiming to increase our knowledge of the molecular mechanisms that underlie the host responses and their effects on bacterial pathogenicity. Understanding the interactions between bacteria and the host will hopefully enable the development of new strategies for the treatment of infectious disease. In paper I, we investigated the effect of N. gonorrhoeae on the growth factor amphiregulin in cervical epithelial cells and found that the processing and release of amphiregulin changes upon infection. In paper II, we examined the expression of the transcription factor early growth response-1 (EGR1) in epithelial cells during bacterial colonization. We demonstrated that EGR1 is rapidly upregulated by many different bacteria. This upregulation is independent of the pathogenicity, Gram-staining type and level of adherence of the bacteria, but generally requires viable bacteria and contact with the host cell. The induction of EGR1 is mediated primarily by signaling through EGFR, ERK1/2 and β1-integrins. In paper III, we described the interactions of the uncharacterized protein JHP0290, which is secreted by H. pylori, with host cells. JHP0290 is able to bind to several cell types and induces apoptosis and TNF release in macrophages. For both of these responses, signaling through Src family kinases and ERK is essential. Apoptosis is partially mediated by TNF release. Finally, in paper IV, we showed that certain Lactobacillus strains can reduce the colonization of H. pylori on gastric epithelial cells. Lactobacilli decrease the gene expression of SabA and thereby inhibit the binding mediated by this adhesin.<br><p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 4: Manuscript.</p>
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Chvalkovská, Eva. "Využití různých metod izolace DNA baktérií mléčného kvašení v molekulárně biologických metodách." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2019. http://www.nusl.cz/ntk/nusl-401889.
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This thesis focused on the probiotic bacteria, DNA isolated from these bacteria by three different methods and the effect of isolation on DNA identification using molecular biological methods. Probiotic bacteria are an important part of human intestinal tract. They have an important role in the function of the immune system due to adhesion to the mucosa of the intestinal flora. They create a inhostile environment for pathogens. Probiotic bacteria are commonly taken in the food like dairy products or food supplements. However, overuse of antibiotics is at risk of passing on the intrinsic resistance that probiotic bacteria have to the pathogenic bacteria. The intrinsic resistence they have to maintain the natural homeostasis of the intestinal tract. It is important to effectively identify risky probiotic bacteria that have the ability to transmit resistance to eliminate their presence in food and dietary supplements. Three methods of DNA isolation like phenol extraction method, magnetic particle isolation and commercial kit isolation were used in the experimental part. DNA was isolated from three dietary supplements, namely Biopron 9 premium, Linex forte and GS Lactobacily forte 21. The purity and concentration of the isolated DNA was detected spectrophotometrically. The presence of individual DNA strains in dietary supplements was confirmed by real-time polymerase chain reaction. The best method of isolation in terms of purity and concentration of isolated DNA was evaluated by RT-PCR and spectrophotometry using a commercial kit isolation method.
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Gaviria, Cantín Tania Cristina. "Factores Gre de Salmonella enterica serovar Typhimurium, su papel en el control de la filosofía y patogenicidad." Doctoral thesis, Universitat de Barcelona, 2016. http://hdl.handle.net/10803/397788.
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El género Salmonella, está compuesto de bacterias Gram-negativas, no esporuladas, en forma de bacilo. Salmonella tiene importante relevancia a nivel de salud pública ya que es uno de los principales patógenos entéricos tanto en países desarrollados como en vías de desarrollo. En los casos de gastroenteritis notificados en España, Salmonella se posiciona en segundo lugar, después de Campylobacter. En este trabajo se utilizó como organismo modelo de estudio S. enterica serovar Typhimurium (S. Typhimurium), que en humanos causa salmonelosis, gastroenteritis caracterizada por diarrea inflamatoria, originada normalmente tras la ingestión de alimentos o agua contaminados. Los genes de virulencia de S. Typhimurium están localizados mayoritariamente dentro de islas de patogenicidad (SPI). Los genes codificados en la SPI-1 promueben la invasión de células eucariotas, la regulación de la expresión de los genes de la SPI-1 está mediada por HiIA codificada en el gen, hilA, presente en la misma SPI-1. HiIA activa la expresión de los genes que codifican para la síntesis de un sistema de secreción de tipo 3 (T3SS) encargado de secretar e inyectar proteínas efectoras dentro de la célula hospedadora. La expresión de hilA se encuentra bajo el control de unl bucle de regulación, comprendido por las proteínas HiID, HiIC y RtsA. HiID es el regulador predominante de este sistema, mientras que HiIC y RtsA se encargan de amplificar la señal de activación. Por su parte, los genes que contiene la SPI-2, están implicados en causar infecciones sistémicas y la proliferación intracelular de la bacteria. Los factores Gre son factores que regulan la elongación de la transcripción génica en procariotas. Son conocidos por promover la actividad endorribonucleotídica de la ARN polimerasa (ARNpol) cuando ésta se encuentra en un estado de pausa por retroceso causado durante la elongación de la transcripción. A pesar de que los factores Gre han sido bien caracterizados en otras enterobacterias como Escherichia coli, en Salmonella no existen estudios que describan el papel de los factores Gre en la fisiología celular. Así, el objetivo principal de esta tesis doctoral fue estudiar el papel de los factores Gre en la fisiología y patogenicidad de Salmonella. En este estudio describimos que los factores Gre forman parte de la compleja red reguladora de la expresión de los genes de la SPI-1 y SPI-2 de Salmonella. Los resultados obtenidos indican que los factores Gre de Salmonella son esenciales para la correcta expresión de las proteínas efectoras codificadas dentro de la SPI-1 (SipA, SipC y SipD) y fuera de ella (SopE), y que también juegan un papel importante en la motilidad de la célula bacteriana, fenotipos predominantes en la patogenicidad. Se pudo determinar que la regulación de la expresión de los genes de la SPI-1 y la SPI-2 por parte de los factores Gre, es a través de la regulación transcripcional del gen hilD. La regulación mediada por los factores Gre requiere de la región 3'UTR del gen hilD. Además demostramos que la actividad antipausa de la transcripción de los factores Gre es necesaria para la correcta expresi formación de biofilm en Salmonella. Esta regulación al parecer también es ejercida en una región UTR, en este caso en la región 5’UTR del gen csgD, y es independiente de la temperatura. En análisis transcriptómicos mediante la técnica de microarrays, se observó que los factores Gre de Salmonella estarían implicados en la correcta expresión de muchos de los genes adquiridos horizontalmente (HGT)
como son los genes presentes en las islas de patogenicidad, plásmidos y fagos. También se observó que existe un elevado número de genes distribuidos en diferentes categorías funcionales, que son corregulados por los factores Gre en conjunto con la proteína DksA, proteína que incrementa la fidelidad de la transcripción al disminuir la tasa de incorporación incorrecta de nucleótidos. Estos resultados indican que el patrón general de expresión génica de Salmonella es el resultado de una compleja interacción entre los factores Gre y la proteína DksA, que implica el control mutuo, competición por la unión a la ARNpol, y la acción similar u opuesta sobre la actividad de la ARNpol. Con los resultados presentados en esta tesis doctoral se puede concluir que los factores Gre forman parte de la compleja red de regulación de los genes de virulencia de Salmonella.ón de hilD.<br>Gre factors regulate gene transcription elongation in prokaryotes. In Escherichia coli they promote cleavage of the nascent RNA transcript within the elongation complex when the RNA polymerase is paused by a backtracking. Although the Gre factors have been characterized in other enterobacteria, in Salmonella there are not studies about their role in cellular physiology. The main objective of this thesis was to study the role of Gre factors in physiology and pathogenicity of Salmonella. In this study we describe Gre factors that are part of the complex regulatory network of gene expression of Salmonella pathogenicity island-1 (SPI-1) and SPI-2.
The results indicate that Gre factors are pivotal in the control of predominant phenotypes in pathogenicity. They are essential for the correct expression of effector proteins encoded within (SipA, SipC and SipD) and outside SPI-1 (SopE), and they also play an important role in motility of the bacterial cell. It was determined that the regulation of gene expression of SPI-1 and SPI-2 by Gre factors is through transcriptional regulation of hilD gene. Regulation mediated by Gre factors requires hilD 3'UTR region. We demonstrated that Gre antipausa activity during transcription is necessary for the correct expression of hilD.
It was also observed that Gre factors play an important role in transcriptional expression of csgD, main regulator of biofilm formation in Salmonella. This regulation is also apparently exerted through the 5'UTR region of the csgD gene, and is temperature- independent.
In transcriptome analysis using Microarray, it was observed that Gre factors are implicated in the correct expression of many horizontally transferred genes (HGT) such as genes present in pathogenicity islands, plasmids and phages. It was also noted that there is a large number of genes distributed into different functional categories, which are co-regulated by Gre factors together with DksA protein, a protein that increases the accuracy of the transcript to decrease the rate of nucleotide missincorporation. These results indicate that the overall pattern of gene expression of Salmonella is the result of a complex interaction between Gre factors and DksA protein, involving the mutual control, competition for binding to ARNpol, and similar or opposite action on ARNpol activity. We can conclude that Gre factors are part of complex regulatory network of virulence genes of Salmonella.
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Kassotaki, Elissavet. "Elimination of micropollutants in conventional and novel nitrogen removal processes. A comparative assessment of diverse microbial communities capabilities." Doctoral thesis, Universitat de Girona, 2018. http://hdl.handle.net/10803/664342.
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Pharmaceutically active compounds (PhACs) and endocrine disrupting compounds (EDCs) can pose a significant risk to the environment and human health, undermining prosperity. Current wastewater treatment plants (WWTPs) cannot efficiently act as barriers to their release and have been identified as main points of discharge and contamination. The present thesis aimed to investigate the fate of five PhACs (ibuprofen, sulfamethoxazole, metoprolol, carbamazepine and venlafaxine) and five EDCs (estrone, 17β-estradiol, estriol, 17α-ethinylestradiol and bisphenol A) in different systems simulating wastewater treatment scenarios and to identify factors triggering their elimination. A comparative assessment was carried out to determine the contribution of the microbial groups (either autotrophic or heterotrophic) present in different lab, pilot and full-scale treatment systems performing different processes in the removal of the selected compounds. The results indicated that the overall efficiency of wastewater treatment systems can be broadened by combining different aerobic and anaerobic conditions and different types of biomass<br>Els compostos farmacèuticament actius (PhACs) i els pertorbadors endocrins(EDC) poden suposar un risc considerable per al medi ambient i la salut humana. Les estacions depuradores d'aigües residuals (EDAR) no poden actuar de manera eficient com a barreres per al seu alliberament i s'han identificat com a punts principals de descàrrega. La present tesi pretén determinar el destí de cinc PhACs (ibuprofèn, sulfametoxazol, metoprolol, carbamazepina i venlafaxina) i cinc EDCs (estrona, 17β-estradiol, estriol, 17α-etinilestradiol i bisfenol A), en sistemes que simulen escenaris de tractament d'aigües residuals, per identificar els factors claus en la seva eliminació. Es va realitzar una avaluació comparativa per determinar la contribució dels diferents grups bacterians (autòtrofs o heteròtrofs) presents en diferents sistemes a escala de laboratori, pilot i a gran escala. Els resultats indiquen que l'eficiència global dels sistemes de tractament d'aigües residuals es pot ampliar combinant diferents condicions aeròbiques i anaeròbies i tipus de biomassa
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Lawlor, Kirsten. "Distribution of bacteria and bacterial plasmids in lake water sediments." Thesis, University of Liverpool, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240596.
Full textBooks on the topic "Bactera"
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Ernst, Joel D., and Olle Stendahl, eds. Phagocytosis of Bacteria and Bacterial Pathogenicity. Cambridge University Press, 2006. http://dx.doi.org/10.1017/cbo9780511541513.
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D, Ernst Joel, and Stendahl Olle, eds. Phagocytosis of bacteria and bacterial pathogenicity. Cambridge University Press, 2006.
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J, Dring G., Gould G. W, Ellar D. J, Federation of European Microbiological Societies., Society for Applied Bacteriology, and International Symposium on "Fundamental and Applied Aspects of Bacterial Spores" (1982 : University of Cambridge), eds. Fundamental and applied aspects of bacterial spores. Academic Press, 1985.
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Marshall, William. Of microbes and men: The emotions, drama, and mystery of a struggle to correct a 125-year-old mistake and improve our defenses against epidemics and bioterrorism : a public affairs book. AuthorHouse, 2008.
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Marshall, William. Of microbes and men: The emotions, drama, and mystery of a struggle to correct a 125-year-old mistake and improve our defenses against epidemics and bioterrorism : a public affairs book. AuthorHouse, 2008.
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Marshall, William. Of microbes and men: The emotions, drama, and mystery of a struggle to correct a 125-year-old mistake and improve our defenses against epidemics and bioterrorism : a public affairs book. AuthorHouse, 2008.
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Wyatt, G. M. Immunoassays for Food-poisoning Bacteria and Bacterial Toxins. Springer US, 1992. http://dx.doi.org/10.1007/978-1-4615-2001-6.
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A, Lee H., and Morgan M. R. A, eds. Immunoassays for food-poisoning bacteria and bacterial toxins. Chapman & Hall, 1992.
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Wyatt, G. M. Immunoassays for Food-poisoning Bacteria and Bacterial Toxins. Springer US, 1992.
Find full textBook chapters on the topic "Bactera"
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Christensen, Henrik, and Werner Nicklas. "Bacteria and Bacterial Diagnostics." In Laboratory Animal Science and Medicine. Springer International Publishing, 2024. http://dx.doi.org/10.1007/978-3-031-59103-7_10.
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Gul Guven, Reyhan, and Kemal Guven. "Bacterial Toxins." In Food Safety. Nobel Tip Kitabevleri, 2024. http://dx.doi.org/10.69860/nobel.9786053358787.5.
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In the globalizing world, food safety and food-borne pathogenic microorganisms are among the important public health problems. There are more than 250 known foodborne diseases and many different types of viruses, bacteria, parasites, toxins, metals and prions that cause these diseases. Toxic molecules generated by bacteria, whether within or outside the organisms, are commonly referred to as "toxins". Toxins serve as the primary virulence factors generated by a multitude of bacteria responsible for causing severe illnesses in both humans and animals. Toxins are the primary bacterial component leading to health problems. This chapter provides information about bacterial toxins.
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Cohan, Frederick M. "Genomes reveal the cohesiveness of bacterial species taxa and provide a path towards describing all of bacterial diversity." In Trends in the systematics of bacteria and fungi. CABI, 2021. http://dx.doi.org/10.1079/9781789244984.0282.
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Abstract This book chapter argues that bacterial systematists of the mid-20th century fortuitously created a species-level systematics that actually fits an important universal theory of speciation by discussing taxonomy would allow us to infer the important characteristics of any unknown organism once we classify it to species. It turns out, unexpectedly, that bacterial species taxa share a species-like property with the species taxa of zoology and botany. While recombination within species taxa of all these groups fails to prevent diversification within species, recombination nevertheless appears to act universally as a force of cohesion within species taxa. That is, recurrent recombination within species limits neutral sequence divergence within species taxa of plants, animals, and bacteria; recombination also allows a sharing of generally adaptive genes across a species range. The 95% ANI criterion that demarcates the traditionally defined species taxa of bacteria fortuitously also yields groups of bacteria that are subject to the species-like property of cohesion, where recombination prevents neutral sequence divergence among ecotypes within a species. Use of the ANI criterion, then, not only provides an easily used algorithm for demarcating bacterial species; it also places bacterial demarcation on the same theory-based foundation as the species taxonomy of animals and plants.
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Lawley, Trevor, Brian M. Wilkins, and Laura S. Frost. "Bacterial Conjugation in Gram-Negative Bacteria." In Plasmid Biology. ASM Press, 2014. http://dx.doi.org/10.1128/9781555817732.ch9.
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Mikulska, Malgorzata. "Neutropenic Fever." In The EBMT Handbook. Springer International Publishing, 2024. http://dx.doi.org/10.1007/978-3-031-44080-9_35.
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AbstractFever during neutropenia is almost universal after an HCT. In neutropenic HCT recipients, clinicians are faced with a unique combination of issues: (1) high incidence of bacterial bloodstream infections, (2) high mortality in case of infections due to Gram-negative bacteria unless effective antibiotic treatment is provided promptly, and (3) numerous causes of fever other than bacterial infection.
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Malinowska, Agnes. "Bacteria." In Microbium. punctum books, 2023. http://dx.doi.org/10.53288/0396.1.04.
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Bacteria have played a truly outsized role in the evolutionary story of life on earth, and they continue to be crucial to sustaining organisms and ecosystems. Until recently, however, most cultural and scientific interest in bacteria has centered on defeating the nefarious “germ.” This entry focuses in particular on how public health efforts to reign in the threat of bacterial disease in the US around 1900 aligned with the aspirations of a hegemonic Anglo-American culture to control and suppress marginalized groups like immigrants and racial others, easy scapegoats for disease. At the same time, British settler colonialism and, eventually, US government policy catalyzed devastating epidemics amongst Indigenous populations from the colonial period into the twentieth century, such as the tuberculosis crisis in Native health. While bacterial disease has been largely divisive in the US, bacteria themselves can encourage humans to think in terms of cooperation and alliance, rather than the strict enforcement of borders. Both symbiosis—bacteria’s preferred social relation—and binary fission—bacterial reproduction—suggest a radical form of sociality that permeates, ruptures, and transforms “individuals” constantly, so that the one always slips into the collective.
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Lefèvre, Christopher T., Fernanda Abreu, Ulysses Lins, and Dennis A. Bazylinski. "A Bacterial Backbone: Magnetosomes in Magnetotactic Bacteria." In Metal Nanoparticles in Microbiology. Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-18312-6_4.
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Wood, A. P., F. J. Warren, and D. P. Kelly. "Methylotrophic Bacteria in Trimethylaminuria and Bacterial Vaginosis." In Handbook of Hydrocarbon and Lipid Microbiology. Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-540-77587-4_245.
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Paterson, Jamie, Martín López-García, Joseph Gillard, Thomas R. Laws, Grant Lythe, and Carmen Molina-París. "Analysis of Single Bacterium Dynamics in a Stochastic Model of Toxin-Producing Bacteria." In Lecture Notes in Computer Science. Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-91825-5_13.
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AbstractWe stochastically model two bacterial populations which can produce toxins. We propose to analyse this biological system by following the dynamics of a single bacterium during its lifetime, as well as its progeny. We study the lifespan of a single bacterium, the number of divisions that this bacterium undergoes, and the number of toxin molecules that it produces during its lifetime. We also compute the mean number of bacteria in the genealogy of the original bacterium and the number of toxin molecules produced by its genealogy. We illustrate the applicability of our methods by considering the bacteria Bacillus anthracis and antibiotic treatment, making use of in vitro experimental data. We quantify, for the first time, bacterial toxin production by exploiting an in vitro assay for the A16R strain, and make use of the resulting parameterised model to illustrate our techniques.
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Sveinsdottir, Maney, Margret Audur, and Johann Orlygsso. "Ethanol and Hydrogen Production with Thermophilic Bactera from Sugars and Complex Biomass." In Progress in Biomass and Bioenergy Production. InTech, 2011. http://dx.doi.org/10.5772/17404.
Full textConference papers on the topic "Bactera"
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Samoilova, Anna. "https://orcid.org/0000-0002-6551-0955." In Scientific International Symposium “Advanced Biotechnologies - Achievements and Prospects” (VIth Edition). Institute of Genetics, Physiology and Plant Protection, 2022. http://dx.doi.org/10.53040/abap6.2022.73.
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Bacterium Pseudomonas syringae van Hall and its pathovars was placed on the top of the ten most important plant pathogens list due to the huge importance for the science and economics [Mansfield et al, 2012]. At present it is known about 60 pathovars of the bacterium Pseudomonas syringae van Hall. The causative agent of bacterial canker disease, bacterium Ps. syringae pv. syringae, is one of the most economically significant Ps. syringae pathovars which affects about 180 plant species. The bacterial pathogen can substantially reduce the yield of economically important cultures such as pear, apple and quince. Relatively low temperatures and high humidity are favorable for bacteria Ps. syringae pv. syringae growth [Pinheiro et al., 2019]. That is why, the phytopathogen may cause the most serious damage in spring during budding stage of plant vegetation. For to combat bacterial canker agrotechnical, chemical and biological control measures are used. Fungi of the genus Trichoderma as well as bacteria Bacillus subtilis are used as biolo-gical control agents for the bacterial canker disease. The preparation “Pentafag”, elaborated in the Republic of Belarus on the basis of five bacterial viruses strains, bacteriophages, has shown high efficacy in the disease suppressing. Bacteriophages are widely spread and can be detected in the targeted bacteria natural environment. Furthermore, bacteriophages can regulate themselves in the sites of infection, depending of the bacterial population density. Being highly specialized bacterial parasites bac-teriophages, can be applied against antibiotic resistant pathogenic bacteria or when chemical control measures are forbidden, for example, during plants bloom stage. For the moment it is known that bacteriophages from the families, Podoviridae, Myoviridae и Siphoviridae infect Ps. syringae pv. syringae bacteria [Pinheiro et al. 2019, Rabiey et al. 2020]. The aim of the study was to investigate the ability of Ps. syringae pv. syringae bacterio-phage isolate, which we detected in the quince tissues affected with bacterial canker, to inhibit bacteria Ps. syringae pv. syringae growth in the cut quince shoots.
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Steager, Edward, M. Selman Sakar, U. Kei Cheang, et al. "Galvanotactic Control of Self-Powered Microstructures." In ASME 2008 International Mechanical Engineering Congress and Exposition. ASMEDC, 2008. http://dx.doi.org/10.1115/imece2008-66647.
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We are examining microactuation techniques by employing the electrokinetic and galvanotactic behavior of certain bacteria. We cultured selected strains of swarming Serratia marcescens which were attached to microstructures using a blotting technique that creates a bacterial monolayer carpet. These bacterial carpets naturally self-coordinate to propel the microstructures. The microstructures were placed in an open channel and a voltage was applied and polarity was switched. We have demonstrated directional control of the motion of the microstructures patterned with bacteria. This mobility is due to the patterning of bacteria on the microstructure surface and arises from a combination of electrokinetic effects and galvanotaxis.
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Cho, Myoung-Ock, Sunghee Yoon, and Jung Kyung Kim. "Inkjet Printing of High-Density Bacterial Arrays for Biosensor Applications." In ASME 2010 First Global Congress on NanoEngineering for Medicine and Biology. ASMEDC, 2010. http://dx.doi.org/10.1115/nemb2010-13057.
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Inkjet printing technique has been developed and applied in many areas. This rapid and simple technique can dispense small amount of selected material at intended location accurately. Due to these advantages, it has been applied to the field of biology such as tissue engineering and microbiology lately. We developed patterning methods based on inkjet printing technique employing bacteria, and generated two-dimensional bacterial cell array on the agar media using a commercially available thermal inkjet printer reformed partially. In this study, we aimed to apply the inkjet-printed bacterial cell array to biosensor. We measured the maximum resolution, accuracy and reproducibility of the bacterial array printed at 600 dpi. In addition, we were able to print three kinds of bacterial strains simultaneously using color cartridges which also enabling synchronous printing of both bacterial solution and known chemical. We applied this technique for studying the growth response of individual bacteria to different levels of stiffness, and the chemotactic response of bacterial colonies.
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Breica Borozan, Aurica, Despina-Maria Bordean, Gabriel Bujanca, Delia Dumbrava, and Sorina Popescu. "CONTROL OF PLANTS OF LOTUS CORNICULATUS L. ON AEROBIC AND ANAEROBIC FREE NITROGEN-FIXING BACTERIA." In GEOLINKS International Conference. SAIMA Consult Ltd, 2020. http://dx.doi.org/10.32008/geolinks2020/b1/v2/07.
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The free nitrogen fixing bacteria are able to mobilize important soil nutrients, transforming through biological processes the unusable molecular nitrogen into an active form and to improve soil fertility, influence many aspects of plant health and ensure their growth, showing interest for the scientific world and farmers. But, on the other hand, this bacterial segment may be influenced by the edaphic factors and the interconnection with the plants, the growth phase, the physiological state and the root system of the plant, by the root exudates, which demonstrates the importance of the bacterial community monitoring from the area of plants influence throughout the growing periods The aim of this study was to evaluate the influence of the age of the plants used as biofertilizer and soil moisture on the free nitrogen fixing bacterial communities (the genera Azotobacter and Clostridium) associated with the roots of the perennial plants of Lotus corniculatus L. There were two zones of interest, namely the area of influence of the roots of the plants (rhizosphere) but also the more distant area (edaphosphere). For the study of aerobic and anaerobic free nitrogen fixing bacteria soil samples were taken together with adjacent plants of Lotus corniculatus L. The experimental variants were located in the western part of Romania, the plants being cultivated on the same soil type, but on different plots, that were in the I-IV years of culture. The influence of Lotus corniculatus L. plants on the free nitrogen fixing bacteria has been reported in control experimental variants. Isolation and study of this bacterial group from the 8 experimental variants was performed on a specific mineral medium, favorable for the growth of the two bacterial genera. The results were evaluated after 5 and 10 days of incubation. Between the two assesments there were no noticeable differences in the nitrogen fixing bacterial community, except for the stimulatory effect observed in the control vatiant and rhizosphere of the first year culture. The plants influence on aerobic and anaerobic free nitrogen fixing bacteria was obvious in the II and IV years of the Lotus corniculatus L. culture, compared to the 76 control variants and varies substantially depending on the age of the plant. In most analyzed soil samples, both bacterial genera, Azotobacter and Clostridium were present, confirming the known ecological relation of unilateral advantage or passive stimulation of the aerobic bacteria compared to the anaerobic clostridia. Exceptions were the samples from the cultures of the first year (rhizosphere and control), but also the rhizosphere from the culture of the year II, where only anaerobic nitrogen fixing bacteria were detected. Our results suggested that plant-soil interactions exert control over the bacteria being studied.
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Malsam, Jason A., Vishard Ragoonanan, Daniel R. Bond, and Alptekin Aksan. "Desiccation Response of Geobacter sulfurreducens." In ASME 2007 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2007. http://dx.doi.org/10.1115/sbc2007-176271.
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Geobacter sulfurreducens is an electricity producing bacteria. It is used in bacterial fuel cells, microbial-based sensors, and catalytic surfaces for bioremediation. Further development of such applications requires stabilization and preservation of the bacteria as thin films on surfaces. This research investigated G.sulfurreducens response to desiccation to explore the feasibility of room temperature preservation. Room temperature preservation involves drying and storing bacteria at ambient conditions. Dried bacteria can be revived on demand by the addition of water.
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Caraba, Ion Valeriu, Marioara Nicoleta Caraba, Delia Hutanu, Elena Pet, and Roxana Popescu. "EVALUATION OF THE ANTIBACTERIAL POTENTIAL OF THYMUS PULEGIOIDES EXTRACTS." In 23rd SGEM International Multidisciplinary Scientific GeoConference 2023. STEF92 Technology, 2023. http://dx.doi.org/10.5593/sgem2023/6.1/s25.20.
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Increasing resistance of microorganisms to conventional drugs has required scientists to discover new sources of biocides with a broad spectrum of action. Since ancient times, plants and plant derivatives such as essential oils have been used in traditional medicine. In the present study, the ethanolic extracts of the aerial parts (leaves and stem) of Thymus pulegioides were evaluated for their antimicrobial activity against some pathogenic bacteria, Gram+ bacteria: Staphylococcus aureus and Streptococcus pyogenes, respectively Gram- bacteria Escherichia coli. The antibacterial potential was tested by the bacterial cell viability test, the spectrophotometric method. The results of the performed tests indicate a different antibacterial effect depending on the type of vegetative organ from which the extract was made, the concentration tested and the bacterial strain studied. A decrease in the antibacterial potential of the extracts is identified as the concentration decreases, the effect exerted being bacteriolytic or bacteriostatic, at some concentrations the values recorded being almost non-existent. The antibacterial potential of Thymus pulegioides extracts were more evident in Gram+ bacteria compared to Gram- bacteria.
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Muratova, A. A., and L. N. Valentovich. "Inactivation of genes lysR and mtfA increases antagonistic activity of bacteria Pseudomonas brassicacearum S-1." In 2nd International Scientific Conference "Plants and Microbes: the Future of Biotechnology". PLAMIC2020 Organizing committee, 2020. http://dx.doi.org/10.28983/plamic2020.177.
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Genes lysR and mtfA localized in chromosome of bacteria P. brassicacearum S 1 were inactivated. The role of these genes in the expression of strain antagonistic activity against several bacterial and fungal pathogens was investigated. The technique of markerless mutagenesis of bacteria P. brassicacearum was optimized.
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Park, Eun-Jung, Myoung-Ock Cho, and Jung Kyung Kim. "Growth Responses of Swarming and Gliding Bacteria on Substrates With Different Levels of Stiffness." In ASME 2010 First Global Congress on NanoEngineering for Medicine and Biology. ASMEDC, 2010. http://dx.doi.org/10.1115/nemb2010-13154.
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We conducted experiments to decipher the interplays among bacterial motility, surface stiffness of culture medium, and growth of colony when bacteria grow on semi-solid substrate. We observed the growth kinetics of two kinds of bacteria, swarming Escherichia coli (E.coli) and gliding Myxococcus Xanthus (M.xanthus), grown on semi-solid agar substrates with different stiffness. The colony of M.xanthus moved by traction force on the surface shows a tendency to grow larger on soft substrate. The colony of E.coli using flagella shows a similar tendency in the early phase but later grows smaller on substrate with lower stiffness. We found that the growth of bacterial colony is affected by the mechanical properties of the substrate and the type of bacterial motility as well.
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Bohinc, Klemen. "BACTERIAL ADHESION ON FOOD CONTACT SURFACES." In 8th Workshop Food and Drug Safety and Quality. Vinča Institute of Nuclear Sciences - National Institute of the Republic of Serbia, 2024. http://dx.doi.org/10.46793/8fdsq.ilb1kb.
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Bacterial contamination of food contact surfaces can cause foodborne outbreaks. In this study, the bacterial adhesion of different bacterial species on food contact surfaces is considered. For a better understanding the bacterial adhesion, first, the contact surfaces and bacteria need to be characterized. Later the bacterial adhesion extent on contact surfaces can be determined by different techniques. The adhesion results can be, at the end, connected to the food safety issues and quality of the food item
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Krebsbach, Meaghen A., and Karim H. Muci-Ku¨chler. "Effect of Initial Surface Concentration on Bacterial Distribution in a Surrogate Ballistic Wound." In ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-64243.
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In ballistic injuries, contamination can be carried from the environment, clothing, and skin surface into the wound track. Bacteria and contaminated debris can be introduced into the wound by several means, including physical transport by the projectile or by the suction caused by the formation and collapse of the temporary wound cavity. In this paper, the relationship between initial bacterial concentration on the surface and resultant bacterial distribution along the wound channel is examined using a leg surrogate. Escherichia coli strain K-12 was used to represent skin surface contamination. In order to reduce the possibility of contamination by outside bacteria and assist in colony visualization, the E. coli first underwent a transformation protocol to express Green Fluorescent Protein and to be resistant to the antibiotic ampicillin. Different concentrations of bacteria were pipetted onto circular filter paper and placed onto the surface of a ballistic gelatin leg surrogate, and an 11.43-mm (0.45-in) caliber projectile was shot through the contaminated area into the gel. The “wound track” was sliced into small, evenly spaced samples and the permanent cavity was removed using a biopsy punch, liquefied, and grown on selective lysogeny broth media containing ampicillin. Examination of a normalized bacterial colony count and normalized area covered per segment allowed comparison of variations in the initial concentration, and confirmed that within a range the normalized contamination distribution trend along the “wound track” remained similar. This verification allowed additional confidence in results obtained using this bacteria distribution methodology by eliminating concerns over small variations in initial bacterial concentration.
Reports on the topic "Bactera"
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Goddard, Alan, and Rachel Pateman. Exploring the chopping board microbiome – lessons learned. Food Standards Agency, 2023. http://dx.doi.org/10.46756/sci.fsa.eaf949.
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Household surfaces are a well-known source of bacterial contamination, with ~40% of outbreaks of foodborne infections in Europe occurring at home. Whilst disease-causing bacteria may arrive in the home in contaminated food, it is also likely that many disease outbreaks are caused by poor hygiene and cross-contamination from raw food. A key site of such microbial contamination is chopping boards.
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Wilde, E. W., J. C. Radway, T. C. Hazen, and P. Hermann. Immobilization of degradative bacteria in polyurethane-based foams: embedding efficiency and effect on bacterial activity. Office of Scientific and Technical Information (OSTI), 1996. http://dx.doi.org/10.2172/565240.
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Gottlieb, Yuval, Bradley Mullens, and Richard Stouthamer. investigation of the role of bacterial symbionts in regulating the biology and vector competence of Culicoides vectors of animal viruses. United States Department of Agriculture, 2015. http://dx.doi.org/10.32747/2015.7699865.bard.
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Symbiotic bacteria have been shown to influence host reproduction and defense against biotic and abiotic stressors, and this relates to possible development of a symbiont-based control strategy. This project was based on the hypothesis that symbionts have a significant impact on Culicoides fitness and vector competence for animal viruses. The original objectives in our proposal were: 1. Molecular identification and localization of the newly-discovered symbiotic bacteria within C. imicola and C. schultzei in Israel and C. sonorensis in California. 2. Determination of the prevalence of symbiotic bacteria within different vector Culicoides populations. 3. Documentation of specific symbiont effects on vector reproduction and defense: 3a) test for cytoplasmic incompatibility in Cardinium-infected species; 3b) experimentally evaluate the role of the symbiont on infection or parasitism by key Culicoides natural enemies (iridescent virus and mermithid nematode). 4. Testing the role(s) of the symbionts in possible protection against infection of vector Culicoides by BTV. According to preliminary findings and difficulties in performing experimental procedures performed in other insect symbiosis systems where insect host cultures are easily maintained, we modified the last two objectives as follows: Obj. 3, we tested how symbionts affected general fitness of Israeli Culicoides species, and thoroughly described and evaluated the correlation between American Culicoides and their bacterial communities in the field. We also tried alternative methods to test symbiont-Culicoides interactions and launched studies to characterize low-temperature stress tolerances of the main US vector, which may be related to symbionts. Obj. 4, we tested the correlation between EHDV (instead of BTV) aquisition and Cardinium infection. Culicoides-bornearboviral diseases are emerging or re-emerging worldwide, causing direct and indirect economic losses as well as reduction in animal welfare. One novel strategy to reduce insects’ vectorial capacity is by manipulating specific symbionts to affect vector fitness or performance of the disease agent within. Little was known on the bacterial tenants occupying various Culicoides species, and thus, this project was initiated with the above aims. During this project, we were able to describe the symbiont Cardinium and whole bacterial communities in Israeli and American Culicoides species respectively. We showed that Cardinium infection prevalence is determined by land surface temperature, and this may be important to the larval stage. We also showed no patent significant effect of Cardinium on adult fitness parameters. We showed that the bacterial community in C. sonorensis varies significantly with the host’s developmental stage, but it varies little across multiple wastewater pond environments. This may indicate some specific biological interactions and allowed us to describe a “core microbiome” for C. sonorensis. The final set of analyses that include habitat sample is currently done, in order to separate the more intimately-associated bacteria from those inhabiting the gut contents or cuticle surface (which also could be important). We were also able to carefully study other biological aspects of Culicoides and were able to discriminate two species in C. schultzei group in Israel, and to investigate low temperature tolerances of C. sonorensis that may be related to symbionts. Scientific implications include the establishment of bacterial identification and interactions in Culicoides (our work is cited in other bacteria-Culicoides studies), the development molecular identification of C. schultzei group, and the detailed description of the microbiome of the immature and matched adult stages of C. sonorensis. Agricultural implications include understanding of intrinsic factors that govern Culicoides biology and population regulation, which may be relevant for vector control or reduction in pathogen transmission. Being able to precisely identify Culicoides species is central to understanding Culicoides borne disease epidemiology.
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Yedidia, I., H. Senderowitz, and A. O. Charkowski. Small molecule cocktails designed to impair virulence targets in soft rot Erwinias. United States-Israel Binational Agricultural Research and Development Fund, 2020. http://dx.doi.org/10.32747/2020.8134165.bard.
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Chemical signaling between beneficial or pathogenic bacteria and plants is a central factor in determining the outcome of plant-microbe interactions. Pectobacterium and Dickeya (soft rot Erwinias) are the major cause of soft rot, stem rot, and blackleg formed on potato and ornamentals, currently with no effective control. Our major aim was to establish and study specific bacterial genes/proteins as targets for anti-virulence compounds, by combining drug design tools and bioinformatics with experimental work. The approach allowed us to identify and test compounds (small molecules) that specifically interfere with the activities of these targets, by this impairing bacterial virulence. Two main targets were selected within the frame of the BARD project. The first is the ATP-binding cassette (ABC) transporters and methyl-accepting chemotaxis proteins (MCP) that have been characterized here for the first time in Pectobacteriaceae, and the second is the quorum sensing (QS) machinery of Pectobacterium with its major proteins and in particular, the AHL synthase ExpI that was identified as the preferred target for inhibition. Both systems are strongly associated with bacterial virulence and survival in planta. We found that Pectobacteriaceae, namely Dickeya and Pectobacterium, encode more ABC transporters and MCP in their genomes, compared to other bacteria in the order. For MCP, soft rot Pectobacteriaceae not only contain more than 30 MCP genes per strain, but also have more diverse ligand binding domains than other species in the Enterobacteriales. These findings suggest that both ABC transporters and MCP are important for soft rot Pectobacteriaceae pathogenicity. We now have a selection of mutants in these proteins that may be further explored to understand their direct involvement in virulence. In parallel, we studied the QS central proteins in pectobacteria, the signaling molecule N-acyl-homoserine lactone synthase, ExpI, and the response regulator ExpR, and established their phylogenetic relations within plant pathogenic Gram negative bacteria. Next, these proteins were used for virtual screening of millions of compounds in order to discover new compounds with potential to interfere with the QS machinery. Several natural compounds were tested for their interference with virulence related traits in Pectobacterium and their capability to minimize soft rot infections. Our findings using microcalorimetric binding studies have established for the first time direct interaction between the protein ExpI and two natural ligands, the plant hormone salicylic acid and the volatile compound carvacrol. These results supported a model by which plants interfere with bacterial communication through interkingdom signaling. The collaborative project yielded two research papers and a comprehensive review, which included new computational and bioinformatics data, in Annu. Rev. Phytopathol., the highest ranked journal in phytopathology. Additional two papers are in preparation. In order to transform the fundamental knowledge that have been gained during this collaborative BARD project into agricultural practice, to control soft rot bacteria, we have submitted a continual project.
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Beveridge, Terrance J. Composition, Reactivity and Regulation of Extracellular Metal-Reducing Structures (Bacterial Nanowires) Produced by Dissimilatory Metal - Reducing Bacteria. Office of Scientific and Technical Information (OSTI), 2004. http://dx.doi.org/10.2172/893692.
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Scholten, Johannes. Composition, Reactivity, and Regulations of Extracellular Metal-Reducing Structures (Bacterial Nanowires) Produced by Dissimilatory Metal Reducing Bacteria. Office of Scientific and Technical Information (OSTI), 2006. http://dx.doi.org/10.2172/895881.
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Brossia and Sridhar. L52103 Differentiation of Corrosion Mechanism by Morphological Feature Characterization - Experimental. Pipeline Research Council International, Inc. (PRCI), 2004. http://dx.doi.org/10.55274/r0010952.
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Natural gas pipeline systems often contain liquid water and other corrosive agents such as salts, CO2, H2S, O2, and bacteria. The ability to differentiate between corrosion mechanisms is crucial, if corrosion control and mitigation schemes are to be effective. The present project was undertaken to determine whether pipeline steels develop characteristic morphological features that are diagnostic to distinguish between abiotic and biotic pitting corrosion. The present report describes the experimental approach taken to conduct the tests. A separate report (by Exponent Failure Analysis Associates, Menlo Park, CA) will describe the findings and implications of the research. The work conducted has led to the development of a unique test system that enables introduction of bacterial consortia under conditions simulating operational pipelines. The test system also promotes the growth of sessile over planktonic bacteria. A significant difficulty encountered in conducting the tests is ensuring truly abiotic conditions. Several different steps and procedures were attempted to sterilze the testing system, however, due to its complexity this still proved highly difficult. It is suggested that future abiotic tests either be conducted in a completely separate system or biocides introduced to kill any opportunistic bacteria that may be present or introduced into the system.
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Jelinek, Raz, Paul Dawson, Timothy Hanks, William Pennington, and Julie Northcutt. Bacterial sensors for food processing environments. United States Department of Agriculture, 2013. http://dx.doi.org/10.32747/2013.7598157.bard.
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The overall objective of this project was to develop a new bacterial contaminant sensor based upon polydiacetylene(PDA) which is a unique polymer that changes color and configuration in response to external molecular stimuli. While this polymer has been well studied and has been shown to respond to bacterial stimuli in the laboratory, application to food processing environments has not been demonstrated. One hurdle in the application of biosensors in a food processing environment is interference of food sanitizers with the detection of bacteria. Common food sanitizers were evaluated for their response to PDA and different concentrations paving the way for use of modified PDAs developed by the research team to be used in food plants. Further development of PDA bacterial sensors focused on simplifying its application by immobilizing PDA on cotton and paper for use on swabs, wipes and dip papers. Increasing the sensitivity of PDAs was investigated by attaching fluorophores. Future and continued work will include the decoration of PDAs with apatmers to improve the specificity of the biosensor to food pathogens.
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Austin, Robert H. Computation by Bacteria. Defense Technical Information Center, 2011. http://dx.doi.org/10.21236/ada535062.
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Zchori-Fein, Einat, Judith K. Brown, and Nurit Katzir. Biocomplexity and Selective modulation of whitefly symbiotic composition. United States Department of Agriculture, 2006. http://dx.doi.org/10.32747/2006.7591733.bard.
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Whiteflies are sap-sucking insects that harbor obligatory symbiotic bacteria to fulfill their dietary needs, as well as a facultative microbial community with diverse bacterial species. The sweetpotato whitefly Bemisia tabaci (Gennadius) is a severe agricultural pest in many parts of the world. This speciesconsists of several biotypes that have been distinguished largely on the basis of biochemical or molecular diagnostics, but whose biological significance is still unclear. The original objectives of the project were (i) to identify the specific complement of prokaryotic endosymbionts associated with select, well-studied, biologically and phylogeographically representative biotypes of B. tabaci, and (ii) to attempt to 'cure’ select biotypes of certain symbionts to permit assessment of the affect of curing on whitefly fitness, gene flow, host plant preference, and virus transmission competency.To identify the diversity of bacterial community associated with a suite of phylogeographically-diverseB. tabaci, a total of 107 populations were screened using general Bacteria primers for the 16S rRNA encoding gene in a PCR. Sequence comparisons with the available databases revealed the presence of bacteria classified in the: Proteobacteria (66%), Firmicutes (25.70%), Actinobacteria (3.7%), Chlamydiae (2.75%) and Bacteroidetes (<1%). Among previously identified bacteria, such as the primary symbiont Portiera aleyrodidarum, and the secondary symbionts Hamiltonella, Cardinium and Wolbachia, a Rickettsia sp. was detected for the first time in this insect family. The distribution, transmission, and localization of the Rickettsia were studied using PCR and fluorescence in situ hybridization (FISH). Rickettsia was found in all 20 Israeli B. tabaci populations screened as well as some populations screened in the Arizona laboratory, but not in all individuals within each population. FISH analysis of B. tabaci eggs, nymphs and adults, revealed a unique concentration of Rickettsia around the gut and follicle cells as well as its random distribution in the haemolymph, but absence from the primary symbiont housing cells, the bacteriocytes. Rickettsia vertical transmission on the one hand and its partial within-population infection on the other suggest a phenotype that is advantageous under certain conditions but may be deleterious enough to prevent fixation under others.To test for the possible involvement of Wolbachia and Cardiniumin the reproductive isolation of different B. tabacibiotypes, reciprocal crosses were preformed among populations of the Cardinium-infected, Wolbachia-infected and uninfected populations. The crosses results demonstrated that phylogeographically divergent B. tabaci are reproductively competent and that cytoplasmic incompatibility inducer-bacteria (Wolbachia and Cardinium) both interfered with, and/or rescued CI induced by one another, effectively facilitating bidirectional female offspring production in the latter scenario.This knowledge has implications to multitrophic interactions, gene flow, speciation, fitness, natural enemy interactions, and possibly, host preference and virus transmission. Although extensive and creative attempts undertaken in both laboratories to cure whiteflies of non-primary symbionts have failed, our finding of naturally uninfected individuals have permitted the establishment of Rickettsia-, Wolbachia- and Cardinium-freeB. tabaci lines, which are been employed to address various biological questions, including determining the role of these bacteria in whitefly host biology.