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1
Ghilamicael, Amanuel Menghs. "Isolation and characterization of n-alkane utilizing bacteria, which produce biomulsifiers." Master's thesis, University of Cape Town, 2003. http://hdl.handle.net/11427/4265.
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Includes bibliographical references.Bacterial strains were isolated by enrichment cultures from oil-contaminated soil samples. In the present study, several strains, capable of growing on crude oil, were isolated. Isolates were screened for their inherent abilities to produce bioemulsifiers when they were grown on hydrocarbon substrates.
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Oelofse, Adriaan. "Isolation and characterisation of the antimicrobial peptides produced by acetic acid bacteria." Thesis, Stellenbosch : Stellenbosch University, 2003. http://hdl.handle.net/10019.1/53479.
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Thesis (MSc)--Stellenbosch University, 2003.ENGLISH ABSTRACT: Wine quality is greatly influenced by the number of microorganisms, which occur throughout the winemaking process. Yeasts are responsible for the alcoholic fermentation, the lactic acid bacteria (LAB) are responsible for malolactic fermentation (MLF), while acetic acid bacteria (AAB) are responsible for converting ethanol to acetic acid. These microorganisms are present on the grapes and in the cellar and these consequently serve as gateways to the fermentation tanks where they will affect the wine quality. However, these microorganisms can be seen either as beneficial or as wine spoilage microorganisms, depending on the conditions that prevail throughout the winemaking process. It is thus very important to prevent any process that could lead to the lowering of the wine quality. In this regard, some of the factors that should always be evaluated include the quality of the grapes, winemaking techniques and quality control. One of the measures that have been implemented during winemaking to ensure the microbial stability is the use of chemical preservatives. Sulphur dioxide (502) has been, and is, used widely as primary preservative in winemaking. However, an ever-increasing consumer resistance against the use of chemical preservatives has developed as it poses possible health risks and decreases the sensorial quality of wine. An alternative approach to chemical preservation that has triggered numerous new investigations, is biological preservation or biopreservation. This is the use of the natural microbial flora and/or their antimicrobial products, such as bacteriocins, to inhibit or destroy the other sensitive microorganisms that are unwanted in the same environment. Evidence in the wine industry has shown that bacterial spoilage still is a very common problem in many wineries. This bacterial spoilage can lead to, amongst other, two main problems, which are of great concern to winemakers. This include high levels of volatile acidity, resulting in the wine having a vinegary off-flavour, and sluggish/stuck fermentation, which is the result of compounds such as acetic- and other fatty acids that causes inhibition of the yeast's growth. With acetic acid being the common link in both cases, it became evident that investigations should be performed on the main producer of acetic acid, namely AAB. As a result, AAB turned out to be one of the main spoilage microorganisms associated with winemaking. Most of the research on biopreservation in the food and beverage industry has been performed on the Gram-positive LAB. The fact that their spectrum of inhibition currently excludes most Gram-negative bacteria, specifically AAB, indicated that AAB should be screened in search of possible antimicrobial compounds that could be applied to control their cell numbers during winemaking. No evidence of antimicrobial action amongst AAB could be found in literature, therefore this work was considered novel. The main objectives of this study were to screen wine isolates of AAB for the production of antimicrobial compounds. This was followed by the isolation and preliminary characterisation of the antimicrobial substances produced. Various attempts to optimise the production of the antimicrobial compounds and isolation procedures, were also included. This study forms part of a larger research programme that has been initiated at the Institute for Wine Biotechnology at Stellenbosch University on the biopreservation in wine. Our results indicated that possible antimicrobial compounds of proteinaceous nature, produced by AAB isolated from wine, do exist. It was found that two different species of AAB, namely Acetobacter aeeti and Gluconobacter frateurii, produced antimicrobial compounds that inhibited other species of AAB. Preliminary results indicated that these compounds are heat sensitive and stable in a wide pH range. It was also shown that after the action of proteolytic enzymes, such as proteinase K and a-chemotrypsin, all inhibitory activity was lost. This study also revealed the existence of the species Gluconobacter frateurii, which have not yet been associated with the winemaking environment. This study made a valuable contribution to the limited amount of information and understanding of AAB, not only in the wine environment, but also elsewhere. The results and findings of this research would serve as platform for further projects. This might soon lead to the development of antimicrobial substances or tailored wine-yeasts with antimicrobial abilities, which can be applied during winemaking to assist the winemaker in combatting high cell numbers and subsequent spoilage by AAB.
AFRIKAANSE OPSOMMING: Wynkwaliteit word beïnvloed deur 'n verskeidenheid van mikroorganismes wat regdeur die wynrnaakproses teenwoordig is. Die giste is vir die alkoholiese fermentasie, die melksuurbakterieë (MSB) vir die appelmelksuurgisting, terwyl die asynsuurbakterieë (ASB) vir die omskakeling van etanol na asynsuur verantwoordelik is. AI hierdie mikroorganismes is teenwoordig op die druiwe en in die kelder, en dit dien gevolglik as 'n weg waardeur hulle in die fermentasietenke kan kom om sodoende die wynkwaliteit te beïnvloed. Hierdie mikroorganismes kan egter gesien word as óf voordelig óf as wynbederfmikroorganismes, afhangende van die heersende kondisies gedurende die wynrnaakproses. Dit is daarom baie belangrik om enige proses te voorkom wat tot 'n verlaging in wynkwaliteit kan lei. Wat laasgenoemde aanbetref, is daar sekere faktore wat altyd geëvalueer moet word, naamlik die druifkwaliteit, wynrnaaktegnieke en kwaliteitsbeheer. Een van die maatreëls wat geïmplementeer is om mikrobiologiese stabiliteit tydens die wynrnaakproses te handhaaf, is die gebruik van chemiese preserveermiddels. Swaweidioksied (S02) word algemeen gebruik as primêre preserveermiddel tydens wynrnaak. Daar is egter 'n toenemende verbruikersweerstand teen die gebruik van chemiese preserveermiddels, aangesien dit moontlike gesondheidsrisiko's kan inhou, asook tot 'n verlaging in sensoriese kwaliteit van die wyn kan lei. 'n Alternatiewe benadering vir chemiese preservering, wat reeds tot verskeie nuwe ondersoeke gelei het, is biologiese preservering of biopreservering. Dit is die gebruik van die natuurlike mikroflora en/of hulle antimikrobiese produkte, soos bv. bakteriosiene, om die sensitiewe mikroorganismes wat in dieselfe omgewing voorkom, se groei te inhibeer óf om hulle dood te maak. Aanduidings vanuit die wynbedryf dui daarop dat bakteriese bederf steeds 'n algemene probleem is wat in baie kelders ondervind word. Hierdie bakteriese bederf kan onder andere twee hoofprobleme veroorsaak, wat 'n groot bekommernis vir verskeie wynmakers is. Dié probleme sluit in hoë vlakke van vlugtige suurheid, wat gevolglik die wyn 'n asyn-afgeur gee, en slepende/gestaakte fermentasies, wat die gevolg is van komponente soos asynsuur en ander vetsure, wat die gis se groei inhibeer. Die feit dat asynsuur die gemeenskaplike faktor in beide gevalle was, het daarop gedui dat 'n ondersoek rakende die hoofproduseerder van asynsuur, naamlik ASB, benodig word. ASB word gevolglik as een van die hoofbederforganismes wat met die wynrnaakproses geassosieer word, beskou. Die meeste navorsing oor biopreservering in die voedsel -en drank bedryf is op die Gram-positiewe MSB gedoen. Die spektrum van inhibisie van die bakteriosiene van MSB sluit egter die meeste Gram-negatiewe bakterieë uit, veral ASB, en dit dui daarop dat ASB gesif moet word in 'n soektog na antimikrobiese substanse wat moontlik gebruik kan word om hul getalle tydens die wynrnaakproses te beheer. Geen bewyse kon tot dusver uit die literatuur gekry word met betrekking tot antimikrobiese aktiwiteit teen ASB nie, daarom word hierdie navorsing dus as nuut beskou. Hierdie studie se hoofdoelwittewas om die wyn-isolate van ASB vir die produksie van antimikrobiese peptiede te sif. Dit is gevolg deur die isolasie en voorlopige karakterisering van die geproduseerde antimikrobiese komponente. Daar is ook verskeie pogings aangewend om die produksie van die antimikrobiese substanse, asook die isolasieprosedures, te optimiseer. Hierdie studie vorm deel van 'n groter navorsingsprogram oor biopreservering van wyn wat deur die Instituut vir Wynbiotegnologie by die Universiteit van Stellenbosch geïnisieer is. Die resultate het daarop gedui dat antimikrobiese substanse van proteïenagtige aard, afkomstig vanaf wyn-isolate van ASB, wel bestaan. Daar is gevind dat twee veskillende spesies, naamlik Aeefobaefer aeefi en Glueonobaefer frafeurii, antimikrobiese peptiede produseer, wat ander spesies van ASB kan inhibeer. Voorlopige resultate het getoon dat hierdie substanse hitte-sensitief is en ook stabiel is oor 'n wye pH-reeks. Daar was ook aanduidings dat, ná die aksie van proteolitiese ensieme, soos bv. proteïnase K en a-chemotripsien, al die inhibitoriese aktiwiteit verlore gegaan het. Hierdie studie het ook die voorkoms van die spesies Glueonobaefer frafeurii aangedui, wat nog nie tot dusver met die wynrnaakomgewing geassosieer is nie. Hierdie studie maak 'n waardevolle bydrae tot die beperkte hoeveelheid inligting oor en begrip van ASB, nie net in die wynomgewing nie, maar ook in die algemeen in die natuur. Die bevindinge en resultate van hierdie navorsing sal as basis dien vir verdere projekte wat sal volg. Dit kan moontlik binnekort lei tot die ontwikkeling van antimikrobiese substanse, en ook pasgemaakte wyngiste met antimikrobiese vermoëns, wat tydens die wynrnaakproses gebruik kan word om sodoende die wynmaker in staat te stelom die hoë bakteriese getalle en die gevolglike bederf deur ASB, te beheer.
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Knepper, Janosch [Verfasser]. "Isolation and Identification of Natural Products from Bacteria and Amphibia / Janosch Knepper." München : Verlag Dr. Hut, 2019. http://d-nb.info/1188515799/34.
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Bueno, Silvia Messias. "Bactérias produtoras de biossurfactantes : isolamento, produção, caracterização e comportamento num sistema modelo /." São José do Rio Preto : [s.n.], 2008. http://hdl.handle.net/11449/100904.
Full textAbstract:
Orientador: Crispin Humberto Garcia-CruzBanca: Iracema de Oliveira Moraes
Banca: Alexandre Rodrigo Coelho
Banca: Eleni Gomes
Banca: Fernando Leite Hoffmann
Resumo: Surfactantes são agentes ativos de superfície amplamente utilizados em vários setores industriais. Estas moléculas, com propriedades anfifílicas, são produzidas química ou biologicamente. A grande maioria dos surfactantes disponíveis comercialmente é sintetizada a partir de derivados do petróleo. Em vista de suas vantagens ecológicas, há um grande interesse comercial na substituição de surfactantes sintéticos por naturais. Nesta pesquisa, foram coletadas cinco amostras de solos contaminados e não contaminados por hidrocarbonetos designadas 1, 2, 3, 4 e 5 das quais foram isoladas vinte e oito colônias bacterianas pela técnica de diluição decimal em tubos de ensaio e plaqueamento em placas de Petri contendo meio PCA (Ágar Padrão para Contagem). As bactérias isoladas foram coradas pelo método de Gram para observação das características morfológicas. Destas, apenas treze apresentaram hemólise em placas de Ágar Sangue, o que indicou a presença de biossurfactante. Posteriormente, estas foram cultivadas em meio de produção contendo sais minerais e o caldo de cultura, sem a presença de células, foi utilizado para a determinação da tensão superficial e do índice de emulsificação. As oito bactérias cujos caldos (sem a presença de células) apresentaram diminuição de tensão superficial de no mínimo 20% e índice de emulsificação estável após 24 horas foram selecionadas para realização de testes bioquímicos para identificação. A análise dos resultados destes testes mostrou que as bactérias pertencem ao gênero Bacillus. Foi determinada a otimização da produção de biossurfactantes em caldo de fermentação utilizando diferentes pH (5,0; 6,0; 7,0 e 8,0), tempo de fermentação (48, 72 e 96 horas) e diferentes fontes de carbono (glicose, sacarose, manitol, frutose, glicose + frutose e caldo de cana) nas concentrações 1, 2, 3, 4 e 5%... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Surfactants are surface-active agents widely used in various industries. These molecules, with amphiphilic properties, are produced chemical or biologically. The vast majority of commercially available surfactants is synthesized from oil derivatives. In view of its environmental benefits, there is a large commercial interest in the replacement of natural by synthetic surfactants. In this survey, were collected five samples of contaminated and not contaminated soil by hydrocarbons designated 1, 2, 3, 4 and 5 which were isolated twenty-eight bacterial colonies by the technique of decimal dilution in test tubes, and plating in Petri dishes containing PCA medium (Plate Count Agar) The bacteria isolated were stained by the method of Gram for observation of morphological characteristics. Of these, only thirteen had haemolysis in blood agar plates, which indicated the presence of biosurfactant. Later, they were grown in a production medium containing minerals and the culture broth, without the presence of cells was used to determine the surface tension and the emulsification index. The eight bacteria whose broths (without the presence of cells) had reduction of surface tension of at least 20% and emulsification index stable after 24 hours were selected to carrying out biochemical test for identification. The results of these tests showed the bacteria belong to the genus Bacillus. It was determined the optimization of production of biosurfactants in fermentation broth using different pH (5.0, 6.0, 7.0 and 8.0), fermentation time (48, 72 and 96 hours) and different carbon sources (glucose, sucrose, mannitol, fructose, glucose + fructose and cane juice) at concentrations 1, 2, 3, 4 and 5%. The results showed that pH 5.0 and 7.0; time of 72 hours and fermentation of sucrose at low concentrations had the best production of biosurfactant. The 2C bacteria (Bacillus sp) isolated... (Complete abstract click electronic access below)
Doutor
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Morgan, Joanne. "Screening, isolation and characterisation of antimicrobial/antifungal peptides produced by lactic acid bacteria isolated from wine." Thesis, Stellenbosch : Stellenbosch University, 2003. http://hdl.handle.net/10019.1/53582.
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Thesis (MSc)--Stellenbosch University, 2003.Full text to be digitised and attached to bibliographic record.
ENGLISH ABSTRACT: Winemaking is an age-old tradition that dates back to as early as 6000 BC. In our modern era there are several insects and microorganisms that pose a threat to the grapevine, the environment and the final wine product. Farmers and winemakers are becoming aware of the threat and the fight against disease, spoilage and/or pathogenic microorganisms is on the rise. Currently, the natural environment is being altered through rural developments, pollution and disaster, which in turn is responsible for altering the natural micro flora. The result is a harsh battle between man and microorganism. The weapon used often against microorganisms is chemical preservatives, such as sulphur dioxide. These chemical preservatives change the nutritional value, quality and wholesomeness of the wine. Chemical preservatives suppress the quality of the wine with a reduction in wine consumption by the consumers. Until the 18th century, wine was regarded as a safe drink and prescribed by doctors. In the zo" century alcohol consumption became the focus point of some health campaigners. Medical science restored the good name of wine in the 1990s when it came to light that moderate red wine consumption may aid in preventing heart disease and assist in stress management. The only drawback that lowers consumption levels is the use of chemical preservatives. It is of utmost importance to place the focus on health issues and the development of natural preservation methods that are environmentally friendly and contributes to the overall wholesomeness of the wine. Due to these demands, the scientific community placed the focus of research projects on the development and enhancement of biopreservation methods, in order to minimise chemical preservation use. One of the most promising biocontrol agents is bacteriocins. These proteinaceous molecules produced by various lactic acid bacteria exert antimicrobial activity towards closely related organism. Research has shown that bacteriocins may aid in the prevention of wine-spoilage and enhance natural preservation techniques. Most of the research on biopreservation in food and beverages has been performed on the bacteriocins of LAB. No evidence could be found that indicated bacteriocin production by wine isolated LAB in South Africa. This study is therefore, of utmost importance and is considered to be novel pioneering work for the South African wine industry. The main objective of this study was to screen wine isolated LAB for the production of antimicrobial and/or antifungal compounds. This was followed by the isolation and characterisation of the produced bacteriocins. This study forms part of a greater project that focuses on wine preservation, under the auspices of the Institute for Wine Biotechnology.The research results in this study indicated the production of bacteriocins by wine isolated LAB of South African origin. It was found that numerous isolates exerted antimicrobial activity towards other wine associated LAB. The most predominant species that gave the highest activity was Lactobacillus brevis and Lactobacillus paracasei. Experimental results indicated that the bacteriocins produced by these two species were thermo-stable and active over a wide pH range, including the temperatures and pH values that reign in the South African wine environment. The antimicrobial activity was lost after treatment with proteolytic enzymes, such as proteinase K and lysozyme. The size, production and growth kinetic curves of the bacteriocins under investigation showed similar results that are comparable to other findings in the literature. Antifungal activity was detected against Botryfis cinerea that indicated limited inhibitory activity towards spore germination, but had no effect on hyphal growth. This study provides novel information regarding bacteriocin production by LAB isolated from the South African wine industry. The results indicate the suitability of these bacteriocins as possible biopreservatives in the wine environment. The proposed results obtained in this study will aid in the development of bacteriocinproducing, tailored made wine yeast or LAB that may in future, play vital roles in the winemaking process.
AFRIKAANSE OPSOMMING: Wynmaak is 'n eeu oue tradisie wat terugdateer tot so vroeg soos 6000 jaar v.C. In ons moderne eeu is daar verskeie insekte en mikro-organismes wat In bedreiging vir die wingerdstok, asook die omgewing en die finale wynproduk inhou. Boere en wynmakers word al hoe meer bewus van hierdie bedreiging, terwyl die stryd teen siektes, bederf en/of patogene mikro-organismes ook aan die toeneem is. Tans word die natuurlike omgewing deur landelike ontwikkeling, besoedeling en natuurlike rampe verander, wat op sy beurt weer verantwoordelik is vir die verandering van mikroflora. Die gevolg is 'n harde stryd tussen die mens en mikro-organismes. Die wapen wat gereeld ingespan word in die stryd teen mikro-organismes, is chemiese preserveermiddels, soos swaweidioksied. Hierdie chemiese preserveermiddels verander die voedingswaarde, kwaliteit en die voedsaamheid van die wyn. Dit onderdruk ook die gehalte van wyn, wat meebring dat minder wyn deur die verbruiker gedrink word. Tot en met die agtiende eeu is wyn deur dokters as 'n veilige drankie voorgeskryf. In die twintigste eeu het alkoholverbruik die fokuspunt van gesondheidskamvegters geword. In die 1990's het die mediese wetenskap wyn se goeie naam in ere herstel toe dit aan die lig gekom het dat In matige verbruik van rooiwyn moontlik hartsiektes kan voorkom en help om stres te beheer. Die enigste nadelige faktor wat verbruikersvlakke verlaag, is die gebruik van chemiese preserveermiddels. Dit is uiters noodsaaklik om die fokus op gesondheidskwessies te plaas en die ontwikkeling van natuurlike preserveermetodes wat omgewingsvriendelik is en tot die algehele voedsaamheid van wyn bydra. As gevolg van hierdie eise het wetenskaplikes die fokus geplaas op navorsingsprojekte vir die ontwikkeling en verbetering van biopreserveringsmetodes met die doelom die gebruik van chemiese preserveermiddels te verminder. Een van die belowendste biokontrolemiddels is bakteriosiene. Hierdie proteïenagtige molekule word deur verskeie melksuurbakterieë vervaardig en oefen anti-mikrobiese aktiwiteit teenoor nabyverwante organismes uit. Navorsing het getoon dat bakteriosiene moontlik kan help in die voorkoming van wynbederf en natuurlike preserveertegnieke kan verbeter. Die meeste van die navorsing op biopreservering in voedsel en drank is op die bakteriosiene van melksuurbakterieë uitgevoer. Geen bewys kon gevind word in Suid Afrika wat bakteriosienproduksie deur wyn-geïsoleerde melksuurbakterieë aangedui het nie. Hierdie studie is daarom baie belangrik en word as baanbreker werk vir die Suid Afrikaanse wynbedryf beskou. Die hoofdoel van hierdie studie was om wyn-geïsoleerde melksuurbakterieë vir die produksie van anti-mikrobiese en/of anti-fungiese substanse te toets. Dit is gevolg deur die isolasie en karakterisering van die geproduseerde bakteriosiene. Hierdie studie maak deel uit van 'n groter projek wat fokus op wynpreservering en wat onder leiding van die Instituut van Wynbiotegnologie uitgevoer word. Navorsingsresultate van hierdie studie dui op die produksie van bakteriosiene deur wyn-geïsoleerde melksuurbakterieë van Suid Afrikaanse oorsrong. Daar is gevind dat verskeie isolate anti-mikrobiese aktiwiteit teenoor ander wynverwante malksuurbakterieë uitgeoefen het. Die oorheersende spesie wat die hoogste aktiwiteit getoon het, was Lactobacillus brevis en Lactobacillus paracasei. Eksperimentele uitslae dui daarop dat die bakteriosiene wat deur hierdie twee spesies geproduseer word, termostabiel en aktief is oor 'n wye pH reeks, insluitende die temperature en pH-waardes wat in die Suid Afrikaanse wynomgewing voorkom. Die anti-mikrobiese aktiwiteit het verlore gegaan na behandeling met proteolitiese ensieme soos proteïnase K. Die groote, produksie en groeikinetika kurwes van die bakteriosiene wat ondersoek is, toon vergelykbare resultate met ander bevindings in die literatuur. Anti-fungiese aktiwiteit is opgemerk teen Botrytis cinerea, wat beperkte inhiberende aktiwiteit ten opsigte van spoorontkieming aangedui het, maar geen effek op hifegroei gehad nie. Hierdie studie verskaf nuwe inligting aangaande bakteriosienproduksie deur melksuurbakterieë wat van die Suid Afrikaanse wynomgewing geïsoleer is. Die resultate dui op die geskiktheid van hierdie bakteriosiene as moontlike biopreserveermiddels in die wynbedryf. Die voorgestelde resultate deur hierdie studie verkry sal help in die ontwikkeling van bakteriosien produserende, spesifiek vervaardigse wyngis of melksuurbakterieë, wat in die toekoms 'n baie belangrike rol in die wynmaakproses sal speel.
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Liang, Lanfang. "Investigation of Secondary Metabolites of North Sea Bacteria: Fermentation, Isolation, Structure Elucidation and Bioactivity." Doctoral thesis, [S.l. : s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=96850728X.
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Bueno, Silvia Messias [UNESP]. "Bactérias produtoras de biossurfactantes: isolamento, produção, caracterização e comportamento num sistema modelo." Universidade Estadual Paulista (UNESP), 2008. http://hdl.handle.net/11449/100904.
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bueno_sm_dr_sjrp.pdf: 2813626 bytes, checksum: 7480bc5354e8527f4c5d0ba8f75c4f13 (MD5)Surfactantes são agentes ativos de superfície amplamente utilizados em vários setores industriais. Estas moléculas, com propriedades anfifílicas, são produzidas química ou biologicamente. A grande maioria dos surfactantes disponíveis comercialmente é sintetizada a partir de derivados do petróleo. Em vista de suas vantagens ecológicas, há um grande interesse comercial na substituição de surfactantes sintéticos por naturais. Nesta pesquisa, foram coletadas cinco amostras de solos contaminados e não contaminados por hidrocarbonetos designadas 1, 2, 3, 4 e 5 das quais foram isoladas vinte e oito colônias bacterianas pela técnica de diluição decimal em tubos de ensaio e plaqueamento em placas de Petri contendo meio PCA (Ágar Padrão para Contagem). As bactérias isoladas foram coradas pelo método de Gram para observação das características morfológicas. Destas, apenas treze apresentaram hemólise em placas de Ágar Sangue, o que indicou a presença de biossurfactante. Posteriormente, estas foram cultivadas em meio de produção contendo sais minerais e o caldo de cultura, sem a presença de células, foi utilizado para a determinação da tensão superficial e do índice de emulsificação. As oito bactérias cujos caldos (sem a presença de células) apresentaram diminuição de tensão superficial de no mínimo 20% e índice de emulsificação estável após 24 horas foram selecionadas para realização de testes bioquímicos para identificação. A análise dos resultados destes testes mostrou que as bactérias pertencem ao gênero Bacillus. Foi determinada a otimização da produção de biossurfactantes em caldo de fermentação utilizando diferentes pH (5,0; 6,0; 7,0 e 8,0), tempo de fermentação (48, 72 e 96 horas) e diferentes fontes de carbono (glicose, sacarose, manitol, frutose, glicose + frutose e caldo de cana) nas concentrações 1, 2, 3, 4 e 5%...
Surfactants are surface-active agents widely used in various industries. These molecules, with amphiphilic properties, are produced chemical or biologically. The vast majority of commercially available surfactants is synthesized from oil derivatives. In view of its environmental benefits, there is a large commercial interest in the replacement of natural by synthetic surfactants. In this survey, were collected five samples of contaminated and not contaminated soil by hydrocarbons designated 1, 2, 3, 4 and 5 which were isolated twenty-eight bacterial colonies by the technique of decimal dilution in test tubes, and plating in Petri dishes containing PCA medium (Plate Count Agar) The bacteria isolated were stained by the method of Gram for observation of morphological characteristics. Of these, only thirteen had haemolysis in blood agar plates, which indicated the presence of biosurfactant. Later, they were grown in a production medium containing minerals and the culture broth, without the presence of cells was used to determine the surface tension and the emulsification index. The eight bacteria whose broths (without the presence of cells) had reduction of surface tension of at least 20% and emulsification index stable after 24 hours were selected to carrying out biochemical test for identification. The results of these tests showed the bacteria belong to the genus Bacillus. It was determined the optimization of production of biosurfactants in fermentation broth using different pH (5.0, 6.0, 7.0 and 8.0), fermentation time (48, 72 and 96 hours) and different carbon sources (glucose, sucrose, mannitol, fructose, glucose + fructose and cane juice) at concentrations 1, 2, 3, 4 and 5%. The results showed that pH 5.0 and 7.0; time of 72 hours and fermentation of sucrose at low concentrations had the best production of biosurfactant. The 2C bacteria (Bacillus sp) isolated... (Complete abstract click electronic access below)
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Lukanji, Zinathi, and R. N. Ndip. "Isolation and molecular characterization of Bacillus cereus from cow’s raw milk." Thesis, University of Fort Hare, 2015. http://hdl.handle.net/10353/d1021284.
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Bacillus cereus is a group of ubiquitous facultative anaerobic spore forming Gram-positive rods commonly found in soil. It has been detected and implicated in several contaminated food products and raw milk in dairy farms and it causes foodborne gastroenteritis by producing several toxins. This study is aimed at characterizing virulence determinants of B. cereus from cow‟s raw milk. A total of 400 raw milk samples were collected in Fort Hare Dairy Trust and Middledrift Dairy Farm; and cultured on Polymyxin pyruvate Egg-Yolk Mannitol Bromothymol Agar (PEMBA) for 48 hours at 37°C. DNA was isolated from the isolates and 16S rDNA was amplified and sent to Central Analytical Laboratory for sequencing. The gyrB gene of B. cereus was also used to confirm the identity of the isolates. Antibiotic susceptibility profiles of the isolates together with virulence genes were investigated. Multilocus Sequence typing was used to investigate the genetic relatedness of some selected isolates. Furthermore, spores of the isolates were produced, harvested and their concentrations determined. All (100%) of the isolates were identified as having a 96-99% similarity to B. cereus, B. thuringiensis and B. anthracis using sequencing; while gyrB gene was observed in all (100%) of the isolates. Three virulence genes nheA, nheB, nheC encoding for non haemolysin enterotoxin were amplified in all (100%) the isolates. All (100%) of the isolates were susceptible to doxycycline, gentamycin, tetracycline, ciprofloxacin, chloramphenicol and streptomycin. Resistance to rifampicin and penicillin G was predominant with equal rate of 100%, while susceptibility to erythromycin, clindamycin and doxycycline ranged from 60% to 100%. The selected isolates were related and are descendants of the same ancestor. All (100%) the isolates produced spores. The B. cereus isolates contain virulence genes, has multiple antibiotic drug resistance and produce spores, which poses a health risk to the public and cannot be used as probiotics.
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Vystavělová, Růžena. "Identifikace vybraných druhů bakterií mléčného kvašení v mléčných výrobcích." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2012. http://www.nusl.cz/ntk/nusl-216875.
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Lactic acid bacteria are natural part of the human gastrointestinal tract. They are often used in food supplements and for the production of fermented dairy products. This thesis focuses on the identification of selected species of lactic acid bacteria and bifidobacteria in cheese and dairy products. Bacterial DNA was isolated by magnetic particles P(HEMA-co-GMA) from crude cell lysates from 9 products. Isolated DNA was amplified in genus-specific and species-specific polymerase chain reactions (PCR). The obtained amplicons were detected by agarose gel electrophoresis. The results of PCR were compared with those provided by the manufacturers and there has been declared a match.
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Klein, Timothy Matsiko Ninsiima. "The isolation and characterisation of novel natural products from marine bacterial symbionts." University of the Western Cape, 2015. http://hdl.handle.net/11394/4747.
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>Magister Scientiae - MScDrug-resistant infections are a global health crisis and drastically hinder the treatment options to effectively combat disease. Today, natural products remain an important source of novel drug candidates. Micro-organisms, in addition to being a source of bioactive natural products, represent a sustainable source of these compounds. As the marine environment is largely underexplored, the oceans represent a potential source of novel NPs. This study aimed at the discovery of novel NPs from bacteria associated with novel marine invertebrate species endemic to the South African coast, including a sponge Spongia (Spongia) sp. 001RSASPN and a tunicate, Pseudodistoma africanum Millar, 1954. The methodology comprised of culture-dependent and culture-independent strategies. The former involved the isolation of bacteria associated with the invertebrate species and subsequent screening for anti-microbial activity against a panel of indicator strains including a multi-drug resistant E. coli strain. Anti-bacterial activity was detected in 6.1% and 4% of bacterial isolates from the sponge and tunicate isolates respectively. The culture-independent strategy involved the use of PCR to select bioactive strains likely to contain novel NRPS or PKS secondary metabolite pathways. An NRPS A- domain exhibiting low sequence identity (65%) to reference sequences in the NCBI database was amplified from isolate PE8-15, a strain belonging to the genus Bacillus. This predicted a novel NRPS pathway within this strain. In addition, this isolate exhibited the most diverse anti-microbial profile including anti-bacterial and anti-fungal activity (A.fumigatus ATCC 46645). Therefore, as the most promising candidate, the genome of PE8-15 was sequenced following which 10 secondary metabolite pathways including bacteriocins (5), NRPS (3), siderophore (1) and a terpene pathway were identified. The A-domain amplified from PE8-15 originated from Cluster 4, and NRPS pathway predicted to encode a lipopeptide. Lipopeptides are an important class of compounds with a range of industrial applications in the pharmaceutical, cosmetic as well as food industry. The identification of potentially novel secondary metabolite pathways from even well- studied groups of organisms demonstrates the importance of sequence-based methods in natural product discovery. Furthermore, this study highlights the South African coast as a rich source of microbial natural products and should be exploited further for drug discovery.
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Borisova, Ralitsa Bogomilova. "Isolation of a Rhodococcus Soil Bacterium that Produces a Strong Antibacterial Compound." Digital Commons @ East Tennessee State University, 2011. https://dc.etsu.edu/etd/1388.
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Rhodococci are notable for their ability to degrade a variety of natural and xenobiotic compounds. Recently, interest in Rhodococcus has increased due to the discovery of a large number of genes for secondary metabolism. Only a few secondary metabolites have been characterized from the rhodococci (including 3 recently described antibiotics). Twenty-four new Rhodococcus strains were isolated from soils in East Tennessee using acetonitrile enrichment culturing and identified using 16S rRNA analysis. Forty-seven Rhodococcus strains were screened for antibiotic production using a growth inhibition assay. One strain, MTM3W5.2, had 90% similarity to the Rhodococcus opacus 16S rRNA gene sequence and produced a large zone of inhibition against R. erythropolis and a large number of closely related species. The antimicrobial compound produced by MTM3W5.2 had a large MW of 911.5452 Da and acts much like a bacteriocin but no amino acids were detected in this molecule based on TLC analysis.
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Domingues, Patrícia Maia. "Isolation of estuarine biosurfactant-producing bacteria." Master's thesis, Universidade de Aveiro, 2011. http://hdl.handle.net/10773/7773.
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Mestrado em BiotecnologiaBioremediation has proven to be an effective strategy in the recuperation of oil contaminated ecosystems. However most bacteria used in this processes, while being able to degrade a wide range of the oil hydrocarbons, have limited action due to the low water solubility of these compounds. Hence, a possible solution for this problem would be the use of biosurfactant-producing bacteria, since the presence of surfactants help improve the hydrocarbons dispersal, solubilization and bioavailability. The objective of this work was to assess the biotechnological potential of Ria de Aveiro estuarine system regarding the presence of hydrocarbonoclastic biosurfactant-producing bacteria and to evaluate different combinations of environmental inocula and carbon sources for the isolation of biosurfactants producing bacteria. Selective cultures (diesel, crude and paraffin) were prepared using inocula from different environmental matrixes: samples from the surface microlayer (SML), bulk estuarine sediments and sediments of the rhizosphere of Halimione portulacoides, a characteristic halophyte from the salt marshes of Ria de Aveiro. During the incubation period, the development of the selective cultures was assessed by quantification of colony forming units (CFU). The highest value of CFU was obtained in the crude-sediment culture, while the lowest value was found with the diesel-rhizosphere combination. The DGGE profiles of the 16s rRNA gene fragments of the total community DNA extracted at the end of the incubation of the selective cultures, show that communities were different in terms of structural diversity. The values of the Shannon-Weaver index of diversity indicate that the higher diversity was achieved in the selective cultures with paraffin as carbon source (2.5231), followed by the crude oil (2.2509), and diesel (1.6726) selective cultures. From the selective cultures, 111 presumably hydrocarbonoclastic isolates were obtained after isolation and purification. Of these, 66 were tested for biosurfactant production by the atomized oil assay, with positive results for 17 isolates (25.8%). The environmental matrix with best results was the SML water and diesel was the most effective carbon source. Having in consideration the high number of isolates obtained from the selective cultures and the percentage of biosurfactant producers, the estuarine system of Ria the Aveiro, and in particular the SML, can be regarded as an interesting seedbank for the prospection of hydrocarbonoclastic and biosurfactants producing bacteria. The SML microhabitat shows particularly high biotechnological potential for the isolation of bacterial strains with interesting properties for application in bioremediation strategies in coastal and estuarine areas.
A biorremediação é tida como uma possível estratégia na recuperação de ecossistemas contaminados com hidrocarbonetos. A aplicação eficaz desta tecnologia é, no entanto, muitas vezes limitada pela natureza hidrofóbica dos contaminantes. O recurso a estirpes bacterianas simultaneamente degradadoras de hidrocarbonetos e produtoras de biossurfactantes apresenta um enorme potencial na reciclagem de compostos hidrofóbicos. Assim, o objectivo deste trabalho consistiu em avaliar o potencial biotecnológico do sistema estuarino da Ria de Aveiro quanto à presença de bactérias hidrocarbonoclásticas produtoras de biossurfactantes e a avaliação de várias combinações de inóculos ambientais e fontes de carbono para a obtenção de isolados bacterianos de interesse. Para tal foram realizadas experiências em meios selectivos (diesel, crude e parafina) a partir de inóculos de diferentes matrizes ambientais: amostras da microcamada superficial (SML), sedimentos estuarinos e rizosfera de bancos de Halimione portulacoides, uma planta halófita dos sapais da Ria de Aveiro. O desenvolvimento da cultura ao longo do período de incubação foi avaliado pela contagem de unidades formadoras de colónias (CFUs). A cultura selectiva com maior teor de bactérias cultiváveis foi a de crude-sedimento e aquela em que a abundância bacteriana foi mais baixa foi a de diesel-rizosfera. A partir da análise dos perfis de DGGE dos fragmentos do gene 16s rRNA do DNA total extraído das culturas selectivas verificou-se que no fim do período de incubação, o grau de semelhança entre as comunidades bacterianas das culturas selectivas é relativamente baixo. Pelo índice de diversidade de Shannon-Weaver a maior diversidade estrutural das comunidades bacterianas encontra-se nas culturas selectivas de parafina (2,5231), seguidas das de crude (2.2509) e das de diesel (1.6727). Das culturas selectivas, foi obtido um conjunto de isolados que foi testado quanto à capacidade de produção de biossurfactantes pelo método atomized oil. De 66 isolados testados, 17 produziram resultado positivo (25,8%), sendo a água da SML a matriz ambiental com melhores resultados e o diesel a melhor fonte de carbono para o isolamento de bactérias produtoras de biossurfactantes. Tendo em conta o elevado número de isolados obtidos e a percentagem de produtores de biossurfactantes, pode concluir-se que na Ria de Aveiro, particularmente na SML, existem comunidades bacterianas adaptadas à utilização se substratos hidrofóbicos, com uma boa representação de produtores de biossurfactantes. Os resultados confirmam a perspectiva de que a SML da Ria de Aveiro é um microhabitat com elevado potencial biotecnológico para isolamento de estirpes de bactérias hidrocarbonoclásticas produtoras de biossurfactantes com promissoras aplicações em processos de biorremediação de regiões estuarinas e costeiras após contaminação acidental com hidrocarbonetos de petróleo.
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Oestreicher, Zachery Walter John. "Magnetotactic Bacteria: Isolation, Imaging, and Biomineralization." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1354146141.
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KUTZ, SUSAN MARIE. "ISOLATION AND CHARACTERIZATION OF A HELICALLY TWISTED BACTERIUM RESEMBLING SELIBERIA." Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/184075.
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A seliberia-like bacterium (SLO), isolated from reverse osmosis membranes was characterized by morphological, physiological and DNA studies. The helically twisted cells of this organism were often observed in star-shaped clusters. Depending on nutritional conditions, cells ranged from 0.5 to 21 um in length and possessed prosthecae. Small motile cells were produced by asymmetric fission or by a budding process. Ovoid "generative" cells were observed in mixed culture conditions or when the pure culture isolate was grown in the presence of humic acid. The SLO oxidatively utilized glucose, maltose, xylose, cellobiose, and several amino acids as sole carbon and energy sources. The organism is a strict aerobe and does not anaerobically respire. The moles percent guanine plus cytosine (mol% G + C) of the SLO DNA was 38% as compared with 63-67% for Seliberia stellata. Although the cellular morphology and physiology of the SLO closely resembles that of S. stellata, the SLO is considered to be a new species of Seliberia based on the presence of prosthecae and the mol% G + C.
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Mathopa, Byatlela Abel. "Isolation of bacterial strains capable of efficient conversion of n-alkanes into value added products." Master's thesis, University of Cape Town, 2004. http://hdl.handle.net/11427/4294.
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Includes bibliographical references.Bacteria that are capable of degrading alkane fractions, C12-C13 and C14-C17, were isolated from oil-contaminated soil collected from the petrochemical company, CALTEX Refineries, South Africa. A total of twenty-three environmental strains were isolated. A preliminary procedure, Nile Blue A straining suggested that twelve of the twenty-three environmental strains might accumulate polyhydroxyalkanoates (PHAs) in their cytoplasm, which is a good candidate for biodegradable plastics. The gene that catalyzes PHA polymerization, phaC, was detected using PCR in some of the environmental strains. The strains of interest were identified and characterized biochemically using various techniques and later sequenced by 16S rONA PCR. The environmental isolate 2 showed a 99 % identity to Pseudomonas aeruginosa BHP7 -6 and was for that reason given a name, Pseudomonas aeruginosa MB2SA. P. aeruginosa MB2SA was shown to possess a 0.5 kb internal fragment corresponding to the phaC gene and capable of degrading the alkane fractions, Cn-CI3 and CI4-CI7, effectively. P. aeruginosa MB2SA was shown to grow optimally in the long alkane fraction, Cw C17, and was further grown in pure alkanes, n-dodecane, n-tetradecane, and hexadecane for comparison. In addition, the strain, P. aeruginosa MB2SA, was grown in an appropriate medium for PHA synthesis and high yields of PHA were observed when both the long alkane fraction, Cw CI7, and pure alkane, hexadecane, were employed as sole carbon sources respectively.
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Taraban, Ronald H. "Isolation and characterization of carbofuran and dicamba degrading bacteria." Diss., Virginia Tech, 1993. http://hdl.handle.net/10919/40115.
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Ferreira, Ana Lúcia Morgado. "Isolation and characterization of PHAs-accumulating bacteria from HSSL." Master's thesis, Universidade de Aveiro, 2013. http://hdl.handle.net/10773/13401.
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Mestrado em Biotecnologia - Biotecnologia Industrial e AmbientalPolyhydroxyalkanoates (PHAs) are biodegradable and biocompatible biopolymers. PHAs emerge as a possible solution as substitutes of petroleum based plastics, being produced under the Biorefinery concept, in which wastes and by-products of numerous industries may be used as carbon source. This project aimed the isolation and characterization of organisms able to store PHAs from Hardwood Sulphite Spent Liquor (HSSL), a by-product of the pulp and paper industry. Isolation was performed from a Mixed Microbial Culture (MMC) selected under feast and famine conditions, using some components present in HSSL as substrates, such as acetic acid and xylose. Five pure isolates able to produce PHAs resulted from the successive streaking in solid medium containing HSSL. The purity of the isolates was evaluated through Gram staining and FISH analysis and the PHAs accumulation by Nile Blue staining. Two strains were identified as Rhohococcus spp. and three as Pseudomonas spp.. One isolate of each genus was selected and further studied in terms of growth and PHAs accumulation capability from three distinct carbon sources (HSSL, acetic acid and xylose). Both isolates, Rhodococcus spp. and Pseudomonas spp., were able to grow and use the three carbon sources as well as to produce PHAs. However, both strains showed a higher maximum specific growth rate (μmax) when HSSL was used as carbon source, 0.212 ± 0.0219 h-1 and 0.251 ± 0.0526 h-1, respectively. A qualitative evaluation of the PHAs accumulation through Nile Blue staining exhibited a higher accumulation when acetic acid was used as sole carbon source. In an attempt to identify some of the species responsible for PHAs accumulation of the selected MMC, belonging to the dominant class, Alphaproteobacteria, a 16S rDNA clone library was constructed. It was possible to identity Novosphingobium spp., Sphingobium spp. and Pleomorphomonas spp.
Polihidroxialcanoatos (PHAs) são biopolímeros biodegradáveis e biocompatíveis. Os PHAs são considerados uma solução possível como substitutos dos plásticos derivados do petróleo, podendo ser produzidos no âmbito do conceito de Biorefinaria utilizando resíduos como fonte de carbono. Este trabalho teve como objectivo o isolamento e a caracterização de bactérias produtoras de PHAs a partir de licor de cozimento ao sulfito ácido (HSSL), um sub-produto da indústria papeleira. Os isolamentos foram realizados partindo de uma cultura mista seleccionada para a acumulação de PHAs por imposição de ciclos de fome e fartura, utilizando alguns dos componentes do HSSL como substrato, nomeadamente a xilose e o ácido acético. Após repicagens sucessivas em meio sólido contendo HSSL, foi possível obter cinco isolados puros capazes de acumular PHAs. A pureza dos isolados foi avaliada através de coloração de Gram e análise FISH e a capacidade de acumulação de PHAs por coloração de Azul do Nilo. Duas estirpes foram identificadas como Rhohococcus spp. e três como Pseudomonas spp.. Um isolado de cada género foi seleccionado e estudado em termos de crescimento e capacidade de acumulação de PHAs, a partir de três fontes de carbono distintas (HSSL, ácido acético e xilose). Verificou-se que ambos os isolados, Rhodococcus spp. e Pseudomonas spp., foram capzes de crescer nos três meios e produziram PHAs. Contudo, ambas as estirpe apresentaram uma taxa específica de crescimento (μmax) superior com HSSL como fonte de carbono, 0.212 ± 0.0219h-1 e 0.251 ± 0.0526h-1 respectivamente. Uma avaliação qualitativa da acumulação de PHAs utilizando coloração Azul do Nilo mostrou uma acumulação maior nos ensaios em que o ácido acético era a única fonte de carbono. Numa tentativa de identificar algumas das espécies responsáveis pela acumulação de PHAs da cultura mista seleccionada pertencentes à classe dominante, Alfaproteobactéria, recorreu-se à construção de uma biblioteca de clones 16S rDNA. Foram identificadas as espécies Novosphingobium spp., Sphingobium spp e Pleomorphomonas spp.
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Dragana, Tamindžija. "Isolation and characterization of Cr(VI) tolerant soil bacteria." Phd thesis, Univerzitet u Novom Sadu, Prirodno-matematički fakultet u Novom Sadu, 2019. https://www.cris.uns.ac.rs/record.jsf?recordId=110336&source=NDLTD&language=en.
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In this study, tolerance of soil bacteria to hexavalent chromium (Cr(VI)) was investigated. First, influence of high chromium levels of anthropogenic and geogenic origin on the soil cultivable bacterial community was examined. Next, a number of bacterial strains with high Cr(VI) tolerance were isolated from diverse environmental samples such as soil, sediment, water and waste material. Strains were identified and tested for the level of Cr(VI) tolerance and the ability toreduce toxic Cr(VI) to more innocuous Cr(III). Selected Bacillus cereus group strains were further characterized - their morphological and biochemical characteristics, 16S rRNA and pycA gene sequences, biofilm formation potential and resistance to other heavy metals were determined. Also, more detailed study of their tolerance level and Cr(VI) reduction was conducted. Strain with the highest resistance together with the control chromate sensitive strain were analyzed by STEM EDS for their cellular and endospore Cr content under different conditions. Results indicate Cr(VI) tolerant bacteria are present both in low and high Cr environments. Majority of isolates belonged to the B. cereus group indicating its overall high tolerance to Cr(VI). Certain strains exhibited high tolerance and reduction ability, indicating their possibleusefulness in practical bioremediation application. STEM EDS analysis of Cr(VI)-sensitive B. subtilis PY79 strain and Cr(VI)-resistant B. cereus group strain NCr1a revealed significant differences in their response to Cr(VI) and in their Cr cellular and endospore content.U ovom radu ispitana je tolerantnost zemljišnih bakterija na šestovalentni hrom (Cr(VI)). Prvo, ispitan je uticaj visokog nivoa hroma antropogenog i geogenog porekla na kultivabilnu bakterijsku zajednicu zemljišta. Dalje, izolovani su bakterijski sojevi sa visokom tolerancijom na Cr(VI) iz različitih sredinskih uzoraka kao što su zemljište, sediment, voda i otpadni materijal. Sojevi su identifikovani i određen je nivo njihove Cr(VI) tolerancije i sposobnost redukcije toksičnog Cr(VI) u manje toksični Cr(III). Odabrani sojevi Bacillus cereus grupe su dalje karakterisani – određene su njihove morfološke i biohemijske karakteristike, 16S rDNK i pycA sekvence, potencijal formiranja biofilma i otpornost na druge teške metale. Takođe, sprovedeno je detaljnije ispitivanje njihove tolerancije i redukcije Cr(VI). Soj sa najvišom otpornošću je uporedo sa kontrolnim osetljivim sojem analiziran pomoću STEM EDS na sadržaj hroma u ćelijama I endosporama u različitim uslovima. Rezultati ukazuju da su bakterije tolerantne na Cr(VI) prisutne i u sredinama sa niskim i sa visokim koncentracijama hroma. Većina izolata pripadala je B. cereus grupi što ukazuje na njenu uopšteno visoku otpornost na Cr(VI). Pojedini sojevi su pokazali visoku otpornost i sposobnost redukcije Cr(VI), što ukazuje na mogućnost njihove praktične primene u bioremedijaciji. STEM EDS analiza osetljivog B. subtilis PY79 soja i Cr(VI)- rezistentnog soja B. cereus grupe NCr1a otkrila je značajne razlike u njihovom odgovoru na Cr(VI) i sadržaju Cr u njihovim ćelijama i endosporama.
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Silva, Avalos Juan G. (Juan Guillermo). "Isolation, Characterization and Physiological Studies of Cyanide-Utilizing Bacteria." Thesis, University of North Texas, 1991. https://digital.library.unt.edu/ark:/67531/metadc278291/.
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Ten bacteria capable of growth on the metal-cyano complex, tetracyanonickelate (II) {K2 [Ni(CN)J } (TCN), supplied as the sole nitrogen source, were isolated. Seven isolates were identified as pseudomonads while the remaining three were classified as Klebsiella species. In addition to TCN, all isolates were able to utilize KCN although it was significantly more toxic. The degradation of TCN was most complete when supplied at growth-limiting concentrations, did not occur when ammonia was present, and resulted in the formation of nickel cyanide [Ni(CN)2] as a degradation product.
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Thongmee, Acharawan. "Isolation and Characterization of a New Capsule-Forming Bacterium." Thesis, University of North Texas, 1999. https://digital.library.unt.edu/ark:/67531/metadc500460/.
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A unique, previously undescribed Gram-negative bacterium was isolated from several soils in Texas and extensively characterized in this study. The cells measured 1-2 by 4-6 μm. The distinguishing characteristic of the bacterium is the extraordinary capsular material which surrounds the cells. The new isolates are aerobic, mesophilic, non motile and have the ability to utilize a variety of organic compounds as the sole source of carbon and energy. The organism grows optimally at 30° C and the optimal pH lies between 7.0-8.0. The isolates produce catalase but oxidase is not produced. They do not produce indole or hydrogen sulfide. The organism can hydrolyze gelatin and Tween 80 but not starch, esculin and casein. The major cellular fatty acid is anteiso 15:0. The guanine and cytosine content is 58-62 mole%. The organism's taxonomic position was further established by specific gene probes, 16S rRNA homology, DNA homology and "ribotyping." These data showed that it was most closely related to members of the genus Paenibacillus, although somewhat divergent from other species classified in this genus. After careful evaluation of the results obtained during this study, it is proposed that this unique bacterium be named Paenibacillus velasolus sp. nov.
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Revetta, Randy P. "Isolation and identification of freshwater bacteria antagonistic to Giardia Intestinalis." Cincinnati, Ohio : University of Cincinnati, 2006. http://www.ohiolink.edu/etd/view.cgi?acc%5Fnum=ucin1141305893.
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Thesis (M.S.)--University of Cincinnati, 2006.Title from electronic thesis title page (viewed Apr. 13, 2006). Includes abstract. Keywords: Giardia intestinalis; Cytophaga-Flavobacterium; Cyst degradation; Microbial antagonism. Includes bibliographical references.
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Lee, Wan-Jing. "Isolation and characterisation of phages infecting gram positive food bacteria." Thesis, University of Canterbury. School of Biological Sciences, 2008. http://hdl.handle.net/10092/3429.
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Bacteriophage (phage), virus of bacteria, has been proposed as a mean to inactivate bacteria that are pathogens of humans. Applied prophylatically to food, phage might decrease the numbers of potential pathogens we ingest. Much active research on using the phages of bacteria to control Gram negative foodborne pathogens are described in the literatures, but comparatively little research describes the phages of Gram positive bacteria and their use as biocontrol agents on food. In this work, previous undescribed phages, able to infect Bacillus cereus and Listeria monocytogenes, were isolated from soil and ruminants faecal material, respectively. As the first step in assessing their potential as biocontrol agents, the isolated phages were purified, concentrated and characterised (albeit to different degrees). The Bacillus phages had a narrow host range while the Listeria phages had a broad host range. Listeria phages also infected L. monocytogenes 2000/47, a strain which recurs in New Zealand clinical cases. Both Bacillus and Listeria phages appeared to be of the Myoviridae family judging by their structure in electron micrographs. The Bacillus FWLBc1 and FWLBc2 phages were lytic phages with a latent period of 106 and 102 min at 37°C, and an average burst size of 322 and 300 phages per infected cell, respectively. Moreover, they both had genomes of approximately 134 kb. All newly isolated and characterized phages were chloroform resistant and survived storage better at 4°C than at room or freezing temperatures. Bacillus phages significantly reduced the bacterial population in mashed potatoes within 24 h at room temperature, when applied at a phage to host ratio of 1000. Listeria phages rapidly inactivated the host population to a low optical density. The findings of this thesis will add to the current knowledge of phages in the context of various environmental conditions for different bacteria and will demonstrate the potential of phages as food safety biocontrol agents.
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Duvenage, Wineen. "Detection and isolation of thermophilic acidophilic bacteria from fuit juices." Thesis, Stellenbosch : University of Stellenbosch, 2006. http://hdl.handle.net/10019.1/3016.
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Thesis (Msc Food Sc (Food Science))--University of Stellenbosch, 2006.Fruit juices were until recently considered to only be susceptible to spoilage by yeasts, mycelial fungi and lactic acid bacteria. Spoilage by these organisms was prevented by the acidic pH of fruit juices and the heat-treatment applied during the hot-fill-hold process. Despite these control measures, an increasing number of spoilage cases of fruit juices, fruit juice products and acidic vegetables due to contamination by thermophilic acidophilic bacteria (TAB) have been reported. The genus Alicyclobacillus, containing TAB were first classified as Bacillus, but were reclassified in 1992. Species of Alicyclobacillus are Gram-positive, rod-shaped, endospore-forming bacteria. The unique characteristic of these organisms is the presence of ω-alicyclic fatty acids, such as ω-cyclohexane and ω-cycloheptane, as the major components of the cellular membrane. This organism has been shown to survive pasteurisation conditions of 95°C for 2 min and grows within a pH range of 2.5 to 6.0 and temperatures between 25° and 60°C. The genus currently consists of 11 species, with A. acidoterrestris, A. acidocaldarius and A. pomorum being the only species associated with the spoilage of fruit juices and fruit juice products. The aim of this study was to evaluate culture-dependent and culture-independent approaches for the detection and isolation of Alicyclobacillus spp. from pasteurised South African fruit juices and concentrates. The culture-dependent approach was evaluated by comparing five different growth media, for growth and recovery of A. acidoterrestris, A. acidocaldarius and A. pomorum at different incubation temperatures, from sterile saline solution (SSS) (0.85% (m/v) NaCl), diluted and undiluted fruit juice concentrates. The five media evaluated included potato dextrose agar (PDA), orange serum agar (OSA), K-agar, yeast extract (YSG)-agar and Bacillus acidocaldarius medium (BAM). The culture-independent approach was used to identify the micro-organisms present in fruit juices and concentrates from different South African manufacturers before and after pasteurisation, using polymerase chain reaction (PCR)-based denaturing gradient gel electrophoresis (DGGE) and DNA sequencing. Spread plates of PDA at pH 3.7 and incubation temperature of 50°C for 3 days was found to be the best isolation media for species of Alicyclobacillus from fruit juice and fruit juice concentrate. With the inclusion of a heat shock treatment at 80°C for 10 min the growth media of preference for spores of Alicyclobacillus from fruit juice concentrates was OSA at pH 5.5 and an incubation temperature of 50°C for 3 days. The culture-dependent approach could detect cells or endospores at a minimum concentration of 104 cfu.ml-1 in SSS and diluted fruit juices. PCR-based DGGE analysis was more sensitive and detected cells of Alicyclobacillus spp. from fruit juices and concentrates at a minimum concentration of 103 cfu.ml-1. Alicyclobacillus acidoterrestris was found to be present in South African apple juice, pear juice, white grape juice and aloe vera juice. White grape juice was also found to contain A. pomorum. Other organisms present in the orange, apple, mango and pear juices were two uncultured bacteria that were identified as members of the genus Bacillus, and one uncultured bacterium closely related to Alcaligenus faecalis. This study confirmed the presence of TAB in pasteurised South African fruit juices and concentrates and emphasises the need for the rapid and accurate detection of TAB in food products.
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Lightfoot, D. A. "Isolation and characterisation of nitrogen assimilation genes from photosynthetic bacteria." Thesis, University of Leeds, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355472.
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Walsh, Sally. "The isolation and starvation-survival of thermophilic sulphate-reducing bacteria." Thesis, University of Exeter, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.307293.
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Bulut, Çisem Yenidünya Ali Fazıl. "Isolation and molecular characterization of lactic acid bacteria from cheese/." [s.l.]: [s.n.], 2003. http://library.iyte.edu.tr/tezler/master/biyoteknoloji/T000270.pdf.
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D'Elia, Tom V. "Isolation of Bacteria and Fungi from Lake Vostok Accretion Ice." Bowling Green State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1224865593.
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Pike, R. "Isolation and characterisation of mercury and antibiotic-resistant oral bacteria." Thesis, University College London (University of London), 2005. http://discovery.ucl.ac.uk/1445788/.
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As very little information was available on mercury sensitivity testing, the first aim was to determine the most suitable agar and concentration of mercuric chloride to use in this project. The primary objective of the study was to determine whether mercury released from amalgam fillings could increase the prevalence of mercury-resistant bacteria in the oral flora of children. This was achieved through cross-sectional and longitudinal studies. The second aim was to determine whether changes in mercury resistance correlated with changes in the incidence of antibiotic resistance. The final aim was to determine whether individual mercury-resistant isolates contained the merA gene. In the cross-sectional study, saliva and plaque samples were collected from patients with and without amalgam fillings. No significant differences in the proportion of mercury-resistant bacteria were detected between the two groups. One hundred and thirty nine mercury-resistant bacteria were isolated and 41% (with amalgam) and 33% (without amalgam) of these were also resistant to one or more antibiotics. Resistance to tetracycline was most common. Sixteen patients were enrolled into the longitudinal study. The proportions of mercury-and antibiotic-resistant bacteria were determined on 3 separate occasions (2 pre-amalgam and 1 post-amalgam). There was not a statistically significant change in the incidence of mercury- or antibiotic-resistant bacteria during the month after the installation of the amalgam fillings. However, a linear association between the number of surfaces and proportion of mercury-resistant bacteria was observed. Eighty eight mercury-resistant bacteria were isolated and 27% (pre-amalgam) and 40% (post- amalgam) of these were resistant to one or more antibiotics. Resistance to erythromycin was most common. One hundred and thirty two mercury-resistant bacteria were screened for the merA gene using PCR and 2 sets of primers. Sixty three percent of the streptococci were found to contain the merA gene. Coagulase-negative staphlyococci, Rothia dentocariosa and Neisseria species contained the merA gene, while Staphylococcus aureus and Pseudomonas stutzeri did not. All sequenced amplicons were found to be up to 95% identical to the Bacillus cereus RC607 merA gene. The results of this study have failed to demonstrate any definitive link between the presence of mercury amalgam in teeth and the presence, or proportion, of mercury- or antibiotic-resistant bacteria in the oral cavity of children.
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Minchul, Gim. "Isolation and Identification of Lactic Acid Bacteria from Swedish Foods." Thesis, Örebro universitet, Institutionen för naturvetenskap och teknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-45774.
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Food fermentation is a method widely used in the past to extend the storage life of food. Numerous studies on fermented food have revealed that they not only have biopreservative properties but also health benefits. Lactic acid bacteria are the major group of microorganisms involved in food fermentation and the properties that influence food are primarily due to the compounds released from microorganisms such as organic acids and bacteriocins. Their health benefits are exerted through several mechanisms including inhibiting the growth of pathogenic bacteria and modifying the host immune response. A number of strains that have been investigated show different properties even between the same species thus emphasizing the importance of strain identification. To determine if some traditional fermented Swedish foods contain lactic acid bacteria, bacteria from four fermented Swedish foods (two surströmming and two sausages) were isolated using MRS broth. Bacterial isolates were examined for their colony and cell morphology and Gram staining and were found to be predominantly Gram-positive cocci or rods. 16S rRNA PCR amplifications of selected isolates was performed using universal prokaryotic primers and sequenced. The sequencing results showed that the bacterial isolates from Oskars surströmming Filéer and Gognacs medvurst were Lactobacillus sakei and the isolate from Mannerströms surströmming was Enterococcus sp. This study showed that the traditional Swedish fermented food evaluated did contain lactic acid bacteria.
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Sjögren, Jörgen. "Bioassay-guided isolation and characterisation of antifungal metabolites : studies of lactic acid bacteria and propionic acid bacteria /." Uppsala : Dept. of Chemistry, Swedish University of Agricultural Sciences, 2005. http://epsilon.slu.se/200517.pdf.
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Newbould, E. C. "Catabolism of naphthalene sulphonic acids by three strains of bacteria." Thesis, University of Kent, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379697.
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Taylor, Charles R. "Isolation of environmental lignin-degrading bacteria and identification of extracellular enzymes." Thesis, University of Warwick, 2013. http://wrap.warwick.ac.uk/57457/.
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A novel screening method for detecting lignin-degradation activity on agar plates was developed using nitrated lignin. Using this method, ten lignindegrading bacteria have been isolated from environmental sources, including seven mesophilic soil bacteria and three thermotolerant strains from composted wheat straw. All of the isolates have demonstrated activity towards lignin degradation in the assays, the most active strain being a thermotolerant Sphingobacterium strain from the Bacteroidetes family. The ability of each strain to degrade a variety of aromatic carbon sources and size-fractionated Kraft lignin has been examined by laboratory-scale growth experiments and gel filtration chromatography respectively, and the bioconversion of different lignin-containing feedstocks by three of the most active strains has been examined in a series of laboratory-scale fermentation experiments. Purification of extracellular lignin-degrading enzymes from the culture supernatant of Sphingobacterium sp. has highlighted several different enzyme activities and possible lignin-degrading enzymes.
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Çetin, Ali Emrah Yenidünya Ali Fazıl. "Isolation And Molecular Characterization Of Lactic Acid Bacteria From Raw Milk/." [s.l.]: [s.n.], 2002. http://library.iyte.edu.tr/tezler/master/biyoteknoloji/T000140.rar.
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Aloudah, Eman A. "Isolation and identification of oil degrading bacteria from oil contaminated soil." DigitalCommons@Robert W. Woodruff Library, Atlanta University Center, 2015. http://digitalcommons.auctr.edu/dissertations/2965.
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Oil spills are a universal threat impacting local, national and world communities alike. Bioremediation that is natural, efficient, economical and safe is the best solution for protecting the environment from oil related damages. In this study, motor oil degrading bacteria were isolated from oil-contaminated soil samples from a suburban Atlanta, Georgia community. Mineral salt broth containing 1 Ow-40 motor oil as the sole carbon source was used to isolate motor oil degrading bacteria.
Motor oil tolerant and metabolizing bacteria were identified using morphological and biochemical tests. Two bacterial isolates were then tested for their tolerance varying concentrations of diesel and kerosene oils for comparison with motor oil consumption. Observed results suggest that the isolated bacteria from oil contaminated soil possess abilities to metabolize motor oil, kerosene and diesel. Knowledge of the tolerance ranges of the isolated bacteria can indicate their potential to be of use in the remediation of terrestrial petroleum oil spills in a manner that is natural, economical, quick and efficient.
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Miller, Samuel A. "Electroosmotic Flow Driven Microfluidic Device for Bacteria Isolation Using Magnetic Microbeads." University of Cincinnati / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1544101007184486.
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Phehane, Vuyisile Ntosi. "The isolation and characterisation of thermostable hydantoinases from hydantoinase-producing bacteria." Thesis, Rhodes University, 1999. http://hdl.handle.net/10962/d1004058.
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In order to characterise thermostable hydantoin-hydrolysing enzymes from bacteria, locally-isolated thermophilic organisms were screened for the ability to convert hydantoin to N-carbamylglycine at 55°C using the hydantoinase enzyme. Cell disruption of a selected strain, RU-20-15, was conducted by French pressing to release enzyme from within the cell. In all of the experiments conducted, the amounts of product were low. In view of the low yields of products formed by the thermophiles, a previously-isolated Gram negative strain, RU-KM3L was selected from a number of mesophiles by screening for hydantoinase and carbamylase activity over a 40-55°C temperature range. Hydantoin conversion at 40°C using crude extract from pressed cells of this organism was similar to conversion at 50°C, and therefore subsequent assays were conducted at the higher temperature. The growth kinetics of RU-KM3L cells were studied and the enzyme activities of the extracts were compared in complete and chemically-defined media. The results suggested that the optimal time to harvest cells was at early stationary phase, when using complete medium for culture of cells; the specific activity of enzyme extracts produced by culture in complete medium was higher than that obtained in chemically-defined medium. 5-methylhydantoin was shown to be the preferred substrate for both the hydantoinase and carbamylase enzymes in the crude extract of RU-KM3L. The substrate specificity of the hydantoinase and carbamylase enzymes of the crude RU-KM3L extract was observed to be altered in the presence of increasing amounts of hydantoin, 5,5-dihydrouracil (DHU) and 5-thiouracil (TU) as inducers, showing selectivity for 5-methylhydantoin over hydantoin at inducer concentrations of 0.1 to 1%. A limiting effect on the hydrolysis of 5-methylhydantoin was observed when DHU and 5,5-dimethylhydantoin (DMH) were used as inducers, while the limiting effect on hydantoin specificity was observed when DHU and TU were used as inducers. The limiting effect was observed to be dependent upon the concentration of inducer, and was not observed when hydantoin was used as an inducer. The optimal time for assay of the hydantoinase enzyme in crude extract preparations at 50°C was observed to be 3h. Alkaline conditions were shown to be optimal for both the hydantoinase and carbamylase enzymes of RU-KM3L. Assay for enzyme activities of RU-KM3L extract in the presence of metal ions showed Mn²⁺ ions (and to a lesser extent, Co²⁺) to activate both the hydantoinase and carbamylase activities. Cu²⁺ ions were observed to inhibit the hydantoinase enzyme. In order to determine the location of the enzymes within the cell, cell debris from disrupted cells of RU-KM3L was removed by centrifugation. A decrease in enzyme activity in the supernatant was observed, and suggested association of the enzymes with the cell membrane. Ammonium sulfate fractionation experiments conducted on the crude extract provided further evidence for this result. Sonication of the crude enzyme extract was the only successful method for the releasing of membrane-associated enzyme. Of a number of strategies investigated, the use of sucrose at 50% (w/v) concentration was shown to preserve the hydantoinase and carbamylase enzyme activities during lyophilisation. Furthermore, assay for these enzyme activities showed the activities to be higher after lyophilisation in the presence of sucrose. However, sucrose did not increase the thermostability of lyophilised crude enzyme extracts. Water-miscible organic solvents at 1% concentration were shown to be inhibitory to the hydantoinase and carbamylase enzymes of RU-KM3L, and the inhibition was also observed to increase with increasing concentrations of these solvents. Hydantoinase activity in the presence of water-immiscible organic solvents was shown to increase with an increase in the hydrophobicity of these solvents, but the activity observed was not significantly higher than activity in the absence of solvent when hydantoin and 5-methylhydantoin were used as substrates. The possibility of reversing the hydantoinase enzyme reaction by water-immiscible organic solvents was investigated, and the results obtained suggested that the reaction could be reversed. It was thought that the partitioning of substrates or products into hydrophobic organic solvents could influence the reaction equilibrium, but the partitioning observed was not sufficient to affect reaction rates. Peptide synthesis was shown to have occurred in small amounts when the hydantoinase reaction was carried out in the presence of water-immiscible organic solvents. In conclusion, the hydantoin-hydrolyzing enzyme activity of a crude extract preparation from the bacterial strain RU-KM3L was characterised at elevated temperatures, and in the presence of watermiscible and -immiscible organic solvents.
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Chen, Chyan-Yuh, and 陳虔郁. "Studies on the Isolation of Protease Inhibitor Producer from Marine Fish Intestinal Bacteria." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/91838939636695911014.
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Ribeiro, Susana Isabel Chaves. "Isolation and characterization of bioactive compounds produced by lactic acid bacteria." Doctoral thesis, 2018. http://hdl.handle.net/10400.3/5263.
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Tese de Doutoramento, Ciências Agrárias, especialidade de Tecnologia Alimentar, 02 de maio de 2018, Universidade dos Açores.A caracterização de queijos tradicionais, em especial os de denominação de origem protegida, é extremamente importante, não só para a obtenção do produto final desejável, mas também de um ponto de vista económico e até ecológico. Estes queijos fabricados com leite cru são uma fonte crucial de bactérias do ácido láctico (BAL) geneticamente diversificada, que podem apresentar características promotoras de saúde e tecnológicas relevantes. Desta forma, 114 BAL isoladas de um queijo tradicional Açoriano (queijo do Pico) foram avaliadas pelo seu potencial em produzir compostos bioativos que podem ser benéficos para a saúde e para a segurança do produto final. As características tecnológicas destes isolados foram igualmente estudadas, tendo em mente o desenvolvimento de produtos funcionais com aplicações industriais. Os isolados de BAL foram primeiramente analisados pela sua capacidade de produzir substâncias antimicrobianas, bacteriocinas, contra várias bactérias patogénicas. […]. Em conclusão, o presente trabalho demonstrou o potencial de algumas estirpes de BAL isoladas do queijo do Pico, em produzir compostos bioactivos com relevância para serem utilizados no desenvolvimento de produtos alimentares funcionais.
ABSTRACT: Characterization of traditional cheeses, namely those with Protected Designation of Origin (PDO) status, is of extremely importance, not only for maintaining the quality of the end product, but also for economic and even ecologic reasons. These raw milk cheeses are considered a crucial source of lactic acid bacteria (LAB), genetically diversified, that can offer particular, health promoting and technological features. So, 114 LAB isolated from a traditional Azorean cheese (Pico cheese), were studied for their potential to produce bioactive compounds that can display safety and health benefits. Technological features were also evaluated, having in mind the development of functional food products and further industrial applications. The LAB isolates were firstly screened for production of antimicrobial substances, bacteriocins, against a group of pathogenic bacteria. […]. Overall, the present work demonstrated the potential of several LAB strains isolated from Pico cheese to produce bioactive compounds with high potential to be use in the development of functional foods.
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XU, GENG-FAN, and 許耕凡. "Histamine-related hygienic quality, and isolation of histamine-forming bacteria and degrading bacteria in kimchi products." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/28es2n.
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碩士國立高雄海洋科技大學
水產食品科學研究所
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The thirty-two kimchi products collected from supermarkets in Taiwan, including 18 samples made from Taiwan and 14 samples imported from Korea, were tested to determine the histamine-related quality and occurrence of histamine-forming bacteria and histamine-degrading bacteria. The results showed that Taiwanese and Korean samples had average levels of pH for 4.07 and 4.17, salt content for 2.44 and 3.24%, water activity for 0.976 and 0.969, moisture for 12.42 and 13.94%, total volatile basic nitrogen for 24.87 and 29.08 mg/100g, titratable acid for 0.70 and 0.87%, nitrite 13.43 and 10.53 μg/g, and aerobic plate count for 7.26 and 6.84 log CFU/g, respectively. None of these samples contained total coliform and Escherichia coli. Moreover, cadaverine in nine different biogenic amines had the highest average contents for 9.49 and 4.97 mg/100 g in Taiwanese and Korean samples, respectively. The histamine content in all samples was lower than 1.97 mg/100 g, less than the 5.0 mg/100 g allowable limit suggested by the U.S. Food and Drug Administration. Six weak histamine-forming bacteria capable of producing 0.15-0.34 ppm of histamine in TSBH broth were identified as Bacillus spp. Furthermore, seven histamine-degrading bacteria isolated from kimchi products were identified as Lactobacillus alimentarius (1 strain), L. buchneri (3 strain), Bacillus amyloliquefaciens (1 strain), L. casei (1 strain) and L. plantarum (1 strain). Among them, L. buchneri F-① and L. casei P-① degraded histamine up to 74% in histamine MRS broth. However, the optimal growth condition of L. buchneri F-① was at 37℃, pH 6 and 0% NaCl for 18 h incubation. And, the optimal growth condition of L. casei P-① was at 37℃, pH 7 and 0% NaCl for 18 h incubation.
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LIU, FANG-LING, and 劉芳伶. "Histamine-Related Hygienic Quality and Isolation of Histamine-Forming Bacteria and Histamine-Degrading Bacteria in Salted Seafood Products." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/43981569335863967480.
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碩士國立高雄海洋科技大學
水產食品科學研究所
99
The fifty-seven salted seafood products sold in the fishing village stores in Taiwan, including salted fish product, salted mollusk product and salted shrimp product, were tested to determine the occurrence of histamine, histamine-forming bacteria and histamine-degrading bacteria. The results showed that salted fish product, salted mollusk product and salted shrimp product had average levels of pH for 5.81, 5.11 and 6.21, salt content for 14.1, 9.49 and 8.43%, water activity for 0.77, 0.84 and 0.86, total volatile basic nitrogen for 99.0, 55.6 and 102 mg/100g, and aerobic plate count for3.14、3.02 and 5.09 log CFU/g, respectively. None of these samples contained total coliform and Escherichia coli. The average salt content of salted fish samples was significantly (P<0.05) higher than that of salted mollusk samples and salted shrimp samples, whereas the average Aw value in the salted fish samples was the lowest (P<0.05). Although the average content of each of nine different biogenic amines in all samples was less than 5.0 mg/100 g, 10.5% (6/57) of tested samples had the histamine content greater than the 5.0 mg/100 g allowable limit suggested by the U.S. Food and Drug Administration. One histamine-producing bacterial strain capable of producing 78.5 ppm of histamine in trypticase soy broth supplemented with 1.0 % L-histidine (TSBH) was identified as Bacillus megaterium. The B. megaterium isolate was a halotolerant bacterium with growing well at elevated NaCl concentration to 15% in TSBH medium. Besides, it had a consistent ability to produce >300 ppm of histamine at 10% NaCl concentration in TSBH medium after 72 h. Furthermore, eight histamine-degrading bacteria isolated from salted fish samples and salted mollusk samples were identified as Rummeliibacillus stabekisii (1strain), Agrobacterium tumefaciens (1 strain), Bacillus cereus (2 strains), B. polymyxa (1 strain), B. licheniformis (1 strain), B. amyloliquefaciens (1 strain), B. subtilis (1 strain). Among them, B. polymyxa degraded histamine up to 100% in histamine broth. Therefore, the well range of temperature, pH and salt concentration for growth and histamine degradation of B. polymyxa were 25-37℃, pH 5-9 and 0.5-5% NaCl, respectively. However, the optimal growth and histamine dehydrogenase activity of B. polymyxa were at 30℃, pH 7 and 0.5% NaCl for 24 h incubation.
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Okudoh, Vincent Ifeanyi. "Isolation and characterization of antibiotic(s) produced by bacteria from KwaZulu-Natal soils." Thesis, 2010. http://hdl.handle.net/10413/4974.
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This work reports the continued search for new antibiotics in the relatively under investigated region of KwaZulu-Natal, South Africa. A soil bacterium designated strain N8 with antibacterial activity against both Gram-positive and Gram-negative bacteria was isolated from a poultry farm in Pietermaritzburg, South Africa. The organism was one of approximately 2600 strains isolated from various habitats in the KwaZulu-Natal midlands, South Africa during an actinomycete screening programme. The highest number of antimicrobially-active isolates came from a forest soil site whereas the lowest number was present in a riparian soil.
Morphological, physiological and cultural characteristics indicated that strain N8 belonged in the genus Intrasporangium. In the literature, members of this actinomycete genus have not been associated previously with antibiotic production. Studies on the influence of different nutritional compounds on antibiotic production showed that the highest antibacterial activities were obtained when glycerol at 1% (w/v) was used as sole carbon source in the presence of mineral trace elements.
Using solvent extraction and various chromatographic techniques, the antibiotic produced by strain N8 was recovered from the fermentation broth. The use of a three-solvent system, petroleum ether: acetone: ethyl acetate enhanced the separation of the antibiotic complex in broth. Bioassay results established that the antibacterial agent was in the ethyl acetate fraction (EAF) and chromatographic methods were used in its purification. The chromatographic methods used were: flash column chromatography (FCC), thin-layer chromatography (TLC), and Harrison research chromatotron (HRC). Further purification was carried out by reverse phase high performance liquid chromatography (HPLC). Most of the inactive, coloured material was removed from the antibiotic extract by FCC, while TLC chromatograms run using a range of the most polar to the least polar solvent systems [SS1 (most polar) – SS5 (least polar)] showed best separation of EAF with SS2. TLC chromatograms using SS2 usually showed 3 bands. Bioautograms of SS2-separated EAF revealed that the antibiotic activity was located in the region with an Rf value of 0.56 – 0.64. The Harrison research chromatotron technique also gave good separation of the EAF sample. Preparative HPLC was used as the final purification step for most of the EAF samples. Although, a number of peaks were observed during isocratic-HPLC (IHPLC) runs, they were not as clearly separated as those obtained with gradient-HPLC (GHPLC).
Three major peaks PI, PII and PIII with elution times of 3.56 min, 4.53 min and 23.06 min respectively were revealed under GHPLC runs with decreasing concentrations (100% – 50%) of methanol in water. Methanol concentrations between 50% and 70% in water were considered the optimum GHPLC mobile phases.
Since these chromatographic methods were all time consuming, required large volumes of solvents, and resulted in low yields of the antibiotic, an alternative procedure producing better results was sought. This led to the development of a procedure combining a three-solvent extraction system with a pH precipitation process which efficiently recovered the antibiotic in solid/crystal form. Using this procedure, sufficient quantities of the antibiotic were recovered from the fermentation broth to permit a degree of structural elucidation. Two types of crystals (brown and pink-yellow in colour) were obtained and their chemical natures established by means of 1H- and GCOSY- nuclear magnetic resonance (NMR) and liquid chromatography-mass spectrometry (LC-MS). On further LC-MS analysis, the brown crystals appeared to be a protein and since it did not show inhibitory activity against any of the test organisms, no further studies were carried out on it. The pink-yellow crystals when suspended in a minimal volume of methanol showed inhibitory activity against S. marcescens confirming that the antibiotic activity resided therein. The LC-MS spectrum of these crystals showed a prominent/base peak at 304.2724 [mass to charge ratio (m/z) in positive mode]. The elemental composition of this compound suggests a molecular formula close to C16H36N2O3 with a molar mass of 304.4686 g/mol. No existing name could be assigned to it from the database of known natural compounds. Hence, the possibility that it is a novel antimicrobial compound cannot be excluded.
Characterisation of the antimicrobial substance using GC-MS revealed that it contained at least seven components (A – G). These components were then subjected to mass spectrum analysis and their retention indices compared to computer database listings of known compounds. Components A and B were regarded as representing one compound (possibly isomers) since they have the same molecular weight and formula. Their different retention indices strongly suggest they are indeed isomers. Thus a total of six different compounds were detected in the extract by GC-MS and the molecular formulae assigned to them include: C6H10O (A and B); C6H12O2 (C); C9H14O (D); C8H7N (E); C21H44 (F); and C12H14N2O (G). Since only low probability matches were obtained for A – F and as the sample could not be recovered from the analyser, they were not studied further. The closest match (71% probability) with substances listed in the computer database of natural compounds was for compound G (C12H14N2O) which was thus provisionally identified as
N-acetyltryptamine. A structurally related compound known as melatonin is attributed with the ability to inhibit tumour growth in vivo and in vitro.
Attempts were made to assign a chemical structure to the antibiotic produced by strain N8 using all the data available. The indications are that it is a tryptamine, the chemical structure of which is postulated to be:
In order to monitor the antimicrobial activity of the antibiotic produced by strain N8, bioassays were conducted after all major steps during the isolation and characterization processes. The antimicrobial activity of the pink-yellow crystals was confirmed on the test organisms used during the primary screening phase, namely, Escherichia coli, Pseudomonas fluorescens, Serratia marcescens, Staphylococcus aureus, Enterococcus faecalis and Xanthomonas campestris pv. campestris, and the yeast Candida utilis, indicating that the crude substance had maintained its inhibitory activity against Gram-positive and Gram-negative bacteria, and the yeast tested. The study was extended to include investigations into the use of combinations of the GHPLC separated peaks of the antibiotic (PI, PII and PIII) to improve the efficacy of growth inhibition of the test pathogens for possible use in chemotherapy. Data from these studies showed that PI inhibited the growth of E. coli and X. campestris pv. campestris while PII and PIII inhibited the growth of the latter organism and also that of S. marcescens. Individually, the peaks showed no growth inhibition on Pseudomonas fluorescens but the combination PI+PII+PIII was antimicrobially effective. In all cases, the use of combinations was significantly more effective than the use of any single component alone. For example, the combination of GHPLC PI and PII had a greater growth inhibitory effect (synergic action) against Serratia marcescens than did either alone; the inhibition-zone diameter being double (30mm) that caused by the single peaks (15mm) against S. marcescens. Likewise mixing PI and PIII resulted in a much improved action against X. campestris pv. campestris. These findings may meet the current call by many scientists that all infectious diseases should be treated with a combination of two antibiotics with different mechanisms of action in order to counter the serious problem of emerging bacterial resistance.
Since the antibiotic isolated during this study showed activity against both mammalian and plant pathogenic bacteria it is hoped that this work will encourage further investigation in this field in South Africa. The results obtained should impact on the pharmaceutical industry as well as agriculture and will, hopefully, help curb both plant and human infectious diseases in our African communities. This study also confirmed that KwaZulu-Natal soils do harbour rare actinomycetes that produce novel antimicrobial compounds.Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2010.
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Espírito, Santo Bruno Miguel Prazeres do 1989. "Screening and isolation of compounds with antimicrobial activity produced by multi-resistant bacteria." Master's thesis, 2014. http://hdl.handle.net/10451/11077.
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Tese de mestrado. Microbiologia aplicada. Universidade de Lisboa, Faculdade de Ciências, 2014In the late 20s, after Sir Alexander Fleming discovered the penicillin, a large interest in the search for compounds with antimicrobial activity produced by microorganisms emerged. This event marked the beginning of a new era of antibiotic discovery, where numerous scientist would screen for antibiotics in microorganisms, mostly from the soil. Previous work undertaken at LMB-BioFIG, suggest that ΔphoQ mutation in Stenotrophomonas maltophilia D457 strain is associated to an increased antimicrobial activity. The main focus of this work was to: determine the existence of compounds with antimicrobial activity produced by the aforementioned mutant; determine its spectrum of activity and optimize the culture conditions that are optimal to its production. To answer these questions, a series of biologic susceptibility assays were performed, with both the parental D457 strain and D457ΔphoQ strain. Namely the cross-streak assay, agar-well diffusion assay and drop-diffusion assay. For the later, different culture conditions for the producing strains were tested in order to better understand which conditions favour the compound production, and also, sequential extractions with different organic solvents with different polar characteristics were made to fractionate the obtained batches regarding the polarity of its content, and tested for biologic activity. Finally, in an attempt to unveil the compound of interest, protein quantification, thin layer chromatography and gas chromatography-mass spectrometry analysis were performed on all extracts to better elucidate the nature and structure of the compound. This work revealed that the compound of interest is of non-polar nature produced in low concentrations, around 0.1 g/L. Was only present in the ethyl acetate fraction, with inhibitory activity against the test strains. In neither biologic assay did the parental strain show any inhibitory activity. Additionally, it was revealed by protein quantification assays that the mutant strain secreted almost 3-fold more protein than the parental strain. The results obtained by GC-MS suggest that the compound of interest resembles with the 2,3-dihydroxybenzoic acid, with possible presence of cyclic structures, such as aromatic rings in its molecular structure. However, further analytical procedures must be undertaken to clarify and confirm the structure of the secreted compounds by D457ΔphoQ strain.
No final dos anos 20, após Sir Alexander Fleming ter descoberto a penicilina, emergiu um grande interesse na pesquisa de compostos com atividade antimicrobiana a partir de microrganismos. Este evento marcou o início de uma nova era na descoberta de antibióticos, onde vários cientistas focaram os esforços na pesquisa de antibióticos em microrganismos, especialmente com origem no solo em particular espécies do género Penicillium e Streptomyces. No entanto, nem todos os microrganismos são suscetíveis a estes compostos. Determinadas bactérias e fungos, possuem uma enorme diversidade de mecanismos que conferem resistência a esses compostos. Estes mecanismos de defesa podem basear-se em reações enzimáticas que levam à alteração da estrutura do composto que levam à sua inativação, em aumento de número de bombas de efluxo membranares que rapidamente expulsam os compostos do meio intracelular ou finalmente em alterações no local de ligação do composto que levam à interrupção da ligação entre o antibiótico e o local de ação. A presença dos referidos mecanismos é de elevada relevância medica quando presentes em bactérias patogénicas, uma vez que dificulta o tratamento de doenças pelos métodos convencionais. Atualmente, o número de mortes associadas a infeções causadas por bactérias multirresistentes ronda os 25000 apenas na União Europeia, e este estigma custa cerca de 1,5 mil milhões de euros todos os anos. Stenotrophomonas maltophilia D457 é uma bactéria gram-negativa, popular por ser um organismo com uma exímia capacidade de resistência a antibióticos e metais pesados, ainda, na qualidade de agente patogénico oportunista, está vulgarmente associado a infeções em pacientes cujo sistema imunitário se encontra debilitado e a infeções originadas em hospitais. As infeções mais frequentes causadas por este agente patogénico são associadas a septicemias causadas por cateteres e infeções respiratórias em doentes com fibrose cística. Trabalho desenvolvido previamente no LMB-BioFIG, sugere que uma mutação de frame-knockout mutação do gene phoQ na estirpe Stenotrophomonas maltophilia D457 está associada a um aumento na produção de um composto com atividade antimicrobiana. O gene phoQ faz parte de um sistema de dois componentes PhoP-PhoQ regulador de virulência em diversas bactérias patogénicas. O foco principal deste trabalho foi: determinar a existência de compostos com atividade antimicrobiana produzidos pelo mutante mencionado anteriormente; determinar qual o seu espectro de atividade e otimizar as condições de cultura que são mais favoráveis para a sua produção. Para responder a estas questões, diversos ensaios de atividade biológica foram realizados com ambas as estirpes, quer a parental D457 quer a mutante D457ΔphoQ. Nomeadamente ensaios de cross-streak, difusão de poços de agar e difusão de gotas. Para este último, diferentes condições de crescimento das estirpes produtoras foram testados para determinar quais as condições que favoreciam a produção dos compostos com atividade antimicrobiana, ainda, extrações sequenciais usando diferentes solventes orgânicos, (diclorometano, acetato de etilo e metanol) foram realizadas com o intuito de fracionar os produtos obtidos do crescimento das estirpes produtoras de acordo com a polaridade dos seus conteúdos, culminando no teste da sua atividade biológica contra estirpes da biblioteca do laboratório cuja característica principal é a sua elevada resistência a antibióticos. Finalmente, na tentativa de desvendar qual o composto de interesse, ensaios de quantificação de proteína, cromatografia em camada fina e cromatografia gasosa-espectrometria de massa foram realizados a todos os extratos para melhor elucidar a natureza e a estrutura do composto. Este trabalho revelou que o composto de interesse é de natureza apolar e é produzido em baixas concentrações, menos de 0,1 g/L. Encontra-se apenas presente na fração de acetato de etilo. Esta fração revelou atividade biológica contra diversas estirpes teste, nomeadamente, Acinetobacter haemolyticus VR, Stenotrophomonas maltophilia D457R, Pseudomonas aeruginosa PAO1, Escherichia coli ESLB, Bacillus cereus B4379 e Enterococcus faecalis ATCC 29212. Em nenhum ensaio de atividade biológica, a estirpe parental revelou inibição de crescimento das estirpes teste. Ensaios de quantificação de proteína revelaram que o mutante apresenta uma maior produção de proteínas comparativamente com a estirpe parental, num grau de grandeza 3 vezes superior à parental. Os resultados do GC-MS sugeriram que o composto com atividade biológica se assemelha com o ácido 2,3-dihidroxi benzoico e poderá possuir estruturas cíclicas como anéis aromáticos na sua estrutura. No entanto, adicionais procedimentos analíticos serão necessários para clarificar e confirmar a estrutura dos compostos produzidos pelo mutante ΔphoQ.
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Huang, Chien-Jang, and 黃千讓. "Isolation and molecular-identification of lactic acid bacteria from traditional Mongolian fermented milk products." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/pd82xs.
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碩士國立臺灣大學
動物科學技術學研究所
105
“Probiotics” are live microorganisms that provide health benefits on the host, when administered in adequate amounts. Lactic acid bacteria (LAB) are regarded as “Generally recognized as safe (GRAS)”, and are mainly involving in the fermentation of traditional fermented foods, especially in fermented milk products. For centuries, the nomadic peoples of Mongolia have been producing various kinds of traditional fermented milk products such as Airag (fermented mare’s milk) and Tarag (fermented milk of cows, goats and yaks). To explore the potential probiotic strains, it is very important to develop the culture collection at the first step. In this study, culture- and molecular-based methods were used to investigate the potential LAB probiotic strains in the traditional Mongolian fermented milk products. Based on Enterobacterial Reptitive Intergenic Consensus PCR (ERIC-PCR) profiles, a total of 106 isolates isolated from five Mongolian traditional fermented milk products were categorized into 40 different strains, and identified as belonging to 8 species (Lactobacillus crustorum, Lactobacillus diolivorans, Lactobacillus kefiri, Lactobacillus paracasei, Lactobacillus plantarum subsp. plantarum, Lactococcus. lactis, Leuconostoc lactis, and Leuconostoc pseudomensenteroides) by 16S rRNA and housekeeping gene (pheS and rpoA) sequencing. Lactobacillus kefiri was isolated as the predominant species (24 strains), followed by Lb. crustorum (6 strains). By the screening tests, survival in low pH and bile salt and production of exopolysaccharides (EPS) were characterized as the potential probiotic abilities. As a result, almost of the strains in Lb. crustorum, Lb. diolivorans, and Lb. kefiri showed high survival ability in artificial gastric (pH 3.0) and intestinal (0.3% bile) juices. And, almost of the strains in the Lb. crustorum and Lb. kefiri species showed high ability to produce EPS. Finally, features of survival abilities in low pH and bile salt, and EPS production demonstrated that the two Lb. crustorum strains (MCC0017, MCC0029) could be novel prospective probiotics.
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Benkerroum, Noreddine. "Application of bacteriocins produced by lactic acid bacteria in preserving dairy products and development of a selective medium for Leuconostoc isolation." Thesis, 1992. http://hdl.handle.net/1957/36246.
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Gärtner, Andrea [Verfasser]. "Isolation and characterization of bacteria from the deep sea and their potential to produce bioactive natural products / vorgelegt von Andrea Gärtner." 2011. http://d-nb.info/101204646X/34.
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Khumalo, Lindiwe Lucia. "Isolation and characterisation of antibacterial agents produced by soil bacterium V3." Thesis, 2006. http://hdl.handle.net/10413/990.
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PENG, CHI-EN, and 彭馳恩. "Isolation and Characterization of NovelThermostable Cellulases Produced by Bacteriain Soil Samples." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/s225hc.
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碩士大葉大學
生物產業科技學系
106
Cellulose is the most abundant organic material on earth, it mainly composed by glucose via β-1,4-glycosidic bond. In nature, cellulose is insoluble in water, and is hard to degrade and utilize by animal. In this thesis, bacillus sp. was isolated from soil and thermostable cellulase was found. Zymogram was applied to analyze the cellulase activity, and 3,5-dinitrosalicylic acid was used to analyze the enzyme activity under different working environment such as pH, temperature and metal ion concentration. The cellulase found in this thesis was found to have the best activity when under pH 6 to 7, 60°C, and still have 71.4% activity when under 70°C. Our result indicated that the cellulase found in this thesis can work under difficult environment, and have a good potential for industrial applications.
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Mahmoud, Khaled Attia Shaaban. "Nafisamycin, Cyclisation Product of a New Enediyne Precursor, Highly Cytotoxic Mansouramycins, Karamomycins Possessing a Novel Heterocyclic Skeleton and Further Unusual Secondary Metabolites from Terrestrial and Marine Bacteria." Doctoral thesis, 2009. http://hdl.handle.net/11858/00-1735-0000-0006-ACC1-F.
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LAI, RONG-CHANG, and 賴榮昌. "Studies on the isolation of protease inhibitor producer from marine microorganisms." Thesis, 1992. http://ndltd.ncl.edu.tw/handle/46253267148705609632.
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Gong, Xin-cheng, and 龔信誠. "Isolation and characterization of dioxin biotransformation bacteria." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/94722977541780474015.
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碩士國立中央大學
環境工程研究所
98
The objective of this study was to isolate the indigenous dioxin-degrading bacteria of Taiwan. Also, the characteristics of these bacteria were investigated after isolation followed by culture enrichment and strains acclimation. Three soil samples were gathered from the downstream of the announced dioxin and contamination site. The analytical results of PCDDs/PCDFs and their isomer concentration in all samples confirmed the dioxin contamination of the sampling site with the highest total toxic equivalence of 2450 ng-TEQ/kg of the contaminants. Four bacteria strains which can survive in dioxin media were isolated after sub-culture inoculation. The four strains were identified as Achromobacter xylosoxidans, Ochrobactrum anthropi, Ralstonia mannitolilytica and Agromyces sp.. It was found that all of the strains are gram’s negative in the morphology. In addition, Ochrobactrum anthropi and Agromyces sp. demonstrated the largest configuration with length 2 μm and width 1 μm. Particularly, Agromyces sp. had closest relationship to the PCP-degrading bacterium Mycobacterium chlorophenolicum PCP-1 according to phylogenetic analysis (bootstrap value = 95). The microbial growth kinetics showed that Achromobacter xylosoxidans and Ochrobactrum anthropi had the maximum specific growth rate of 0.115 h-1. Ralstonia mannitolilytica had the smallest half-saturation constants of 43.2 mg/L, meaning least dependence of substrate. Ochrobactrum anthropi has the greatest substrate inhibition coefficient of 0.948 mg/L. However, the microbial growth tests revealed that adding extra carbon source of glucose (1000 mg/L) to the culture medium containing high dioxin concentration (10 μg/kg 2,3,7,8-TCDD) would decrease the growth inhibition. Achromobacter xylosoxidans, Ochrobactrum anthropi, Agromyces sp. could degrade 2,3,7,8-TCDD at lag phase, whereas Ralstonia mannitolilytica decomposed it primarily at log phase. It was also observed that Agromyces sp. had the maximum 2,3,7,8-TCDD degradation efficiency (97%). The results of proteome analysis suggested that two primary proteome molecular weight of 40 and 50kDa for Achromobacter xylosoxidans and Ochrobactrum anthropi had changed during degradation of 2,3,7,8-TCDD. By contrast, 120 kDa proteome of Ralstonia mannitolilytica as well as 20 and 120 kDa proteome of Agromyces sp. would increase when 2,3,7,8-TCDD was degraded.