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Roush, Wendy A. "Pyrimidine Genes in Pseudomonas Species." Thesis, University of North Texas, 2003. https://digital.library.unt.edu/ark:/67531/metadc4395/.
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This thesis is a comparative study of gene arrangements in Pseudomonas species, and is organized into three major sections. The first section compares gene arrangements for different pathways in Pseudomonas aeruginosa PAO1 to determine if the gene arrangements are similar to previous studies. It also serves as a reference for pyrimidine gene arrangements in P. aeruginosa. The second part compares the physical, and genetic maps of P. aeruginosa PAO1 with the genome sequence. The final section compares pyrimidine gene arrangements in three species of Pseudomonas. Pyrimidine biosynthesis and salvage genes will be aligned for P. aeruginosa PAO1, P. putida KT2440, and P. syringae DC3000. The whole study will gives insight into gene patterns in Pseudomonas, with a focus on pyrimidine genes.
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Dumenyo, C. Korsi. "Regulation of pathogenicity in Erwinia and Pseudomonas species /." free to MU campus, to others for purchase, 2000. http://wwwlib.umi.com/cr/mo/fullcit?p9974625.
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Storvoll, Eirin. "Studier av biofilmdannelse hos Pseudomonas species ved forskjellige dyrkingsmetoder." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for bioteknologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-12826.
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SINTEF har en konsernsatsing innenfor systembiologi og dette omfatter blant annet forståelse og bekjempelse av biofilmer. Biofilm kan forårsake skader innenfor medisin, matindustri, havbruk og industri. På en annen side kan biofilmer utnyttes positivt innenfor for eksempel biologisk vannrensing.Formålet med denne oppgaven har vært å etablere relevante teknikker for å studere biofilm. Dette har omfattet utprøving av ulike dyrkingmetoder, samt studier av effekt av dyrkingsbetingelser på biofilmdannelse. Pseudomonas aeruginosa benyttes som modellorganisme i SINTEFs prosjekt, og arbeidet i denne oppgaven har vært utført med den samme organismen. Biofilm ble dyrket i brønnplater og i reaktorer. I tillegg ble det etablert metode for å kvantifisere mengde biofilm, samt etablert metoder for å studere biofilm ved hjelp av konfokalmikroskopi og for studier av genuttrykk ved RT-PCR analyser.Videre ble det valgt å studere produksjon av sekundærmetabolitten pyocyanin i P. aeruginosa. Det ble undersøkt hvilke vekstbetingelser som gir lav og høy produksjon. Disse betingelsene ble videre benyttet til å undersøke uttrykk av gener involvert i pyocyaninsyntese, både planktonisk (frie celler) og i biofilm. I tillegg har oppgaven inkludert undersøkelse av mediets effekt på biofilmdannelse, produksjon av pyocyanin og uttrykk av utvalgte gener. Disse genene involverer gener som inngår i biofilmdannelse, pyocyaninproduksjon og qourum sensing. Det ble valgt å benytte stammene P. aeruginosa PAO1 og P. aeruginosa PA14 i oppgaven. Stammene ble sammenlignet med hensyn på pyocyaninproduksjon, planktonisk vekst og biofilmdannelse.Etablering av teknikker for å studere P. aeruginosa biofilm viste at det ble mulig å studere biofilm i brønnplater og reaktor, men at forbedring og optimalisering av metodene er nødvendig. Det ble vist at P. aeruginosa PAO1 hadde større veksthastighet enn P. aeruginosa PA14. P. aeruginosa PA14 produserte mest pyocyanin og hadde høyest uttrykk av gener involvert i syntese av pyocyanin (phzM og phzS), både planktonisk og i biofilm. Forskjeller i biofilmdannelse ble vist ved at slimdannelse ble sett hos P. aeruginosa PAO1, mens hos P. aeruginosa PA14 ble aggregatdannelse sett.Både forsøk med planktoniske celler (frie celler) og biofilmforsøk viste at fosfatbegrensning inntrer tidligere ved dyrking av P. aeruginosa PAO1 enn ved dyrking av P. aeruginosa PA14. Fosfatbegrensning ga økt pyocyaninproduksjon, men nedsatt biofilmdannelse. Det ble vist at pyocyaninproduksjon initieres i tidlig stasjonærfase for vekst av planktoniske celler og i tidlig biofilmutviklingstrinn. RT-PCR-resultater har vist at genet phzS, som inngår i siste trinn i syntese av pyocyanin, varierer mer med dyrkingsbetingelser, enn det phzM, som inngår i tidligere trinn gjør.
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Thompson, Gillian Ann. "Bacterial interaction in hide biodeterioration with special reference to selected Clostridium species." Thesis, Rhodes University, 1995. http://hdl.handle.net/10962/d1004102.
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Animal hides are the basic raw material of the leather industry and they undergo rapid putrefaction unless "cured". This study investigated the role and interactive effects of three selected bacteria, Pseudomonas aeruginosa. Clostridium histoly ticum and Clostridium sporogenes in in-situ cattle hide degradation using a model system set up for the purpose. The system consisted of 3cm diameter hide pieces contained in sealed jars and sterilised by ethylene oxide to remove resident microbes and inactivate autolytic tissue enzymes. The inocula were prepared either as individual cultures or as combinations of two inocula or all three inocula. Degradative changes during storage at 30°C were measured for up to 8 days using ten different parameters. Initial trials confirmed that the selected inocula were readily isolated from raw hides and could outcompete resident populations to produce putrefactive decomposition. Growth rates and enzyme profiles of the organisms and the effects of nutrients and reductants on their relative denaturative effects were used to standardise the system. Trials on the effects of ethylene oxide indicated the suitability of the method for hide and collagen sterilisation. The findings of in-situ trials with the selected inocula confirmed previous studies of protein putrefaction in that a bacterial succession was evident involving aerobic proteolytic bacteria, micro-aerophilic proteolytic bacteria and strictly anaerobic amino acid degrading bacteria. However, this study showed that the micro-aerophilic collagenase producing C. histolyticum degraded hides at a far greater rate when inoculated on its own than when in the presence of either or both of the other two inocula. It also demonstrated a bacterial antagonism between the two clostridia in which C. sporogenes prevented degradative changes occurring for up to 4-6 days possibly due to cysteine production by C. sporogenes. These findings have implications for hide preservation since maintenance of aerobic conditions and suppression of spore outgrowth could be used to delay growth of collagenase producing clostridia. The use of C. sporogenes as a biocontrol agent is also postulated. The model system was also used to examine salted hides during storage and these studies indicated that Halobacteriaceae do not produce collagenase but that inadequately salted hides could possibly be subject to degradation by delsulfovibrios.
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Arévalo-Ferro, Catalina. "A proteomics view of quorum-sensing regulated and surface induced genes in representative Pseudomonas and Burkholderia species." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=97204650X.
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Karmacharya, Amresh Prasad. "Growth of Mycobacterium avium in dual species biofilms with Pseudomonas aeruginosa." Thesis, Montana State University, 2007. http://etd.lib.montana.edu/etd/2007/karmacharya/KarmacharyaA0507.pdf.
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Interest in the growth of M. avium in biofilms has increased in the last few years. Research has shown that M. avium cells in biofilms are more resistant to disinfectants than their planktonic counterparts. Although M. avium has been detected in biofilms in in situ and laboratory models, information available on M. avium is limited compared to biofilm model species such as Pseudomonas aeruginosa, Escherichia coli, Staphylococcus and Streptococcus. The main objective of the present research was to study the growth of M. avium in biofilms in the presence of P. aeruginosa. Biofilms were grown in sterile tap water on stainless steel coupons in batch mode. Two kinds of reactors were used; mason jars and a recirculation system. Each experiment lasted from 27 to 35 days depending upon the nature of the experiment. The two strains were inoculated in isolation (monospecies) and also in combination (dual species). When inoculated simultaneously, in jar reactor experiments, M. avium density was found lower in dual species than in monospecies biofilms and the difference was statistically significant. However the growth of P. aeruginosa in monospecies did not differ significantly from the dual species biofilms. P. aeruginosa reduced the growth of M. avium. In sequential inoculation experiments an established biofilm of P. aeruginosa did not prevent biofilm formation by M. avium. The growth of M. avium and P. aeruginosa was similar whether they were inoculated as base or invading species. The density of P. aeruginosa remained higher than the density of M. avium in the dual species biofilm, likely due to the higher growth rate of P. aeruginosa compared to that of M. avium. It is important to understand their growth in mixed species biofilms, in order to begin to develop effective methods to both monitor and eventually control this opportunistic pathogen.
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Williams, Jennifer S. "Characterization of bioactive secondary metabolites from Pseudomonas aeruginosa and Prorocentrum species /." Electronic version (PDF), 2003. http://dl.uncw.edu/etd/2003/williamsj/jenniferwilliams.pdf.
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Bandara, Hennaka Mudiyanselage Herath Nihal. "Communal interactions of Candida and bacteria in mixed species biofilms." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B4647951X.
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Robles, Olvera Victor José. "Comparaison de la croissance de pseudomonas species et listeria species en milieu liquide et en viande de boeuf." Clermont-Ferrand 2, 1999. http://www.theses.fr/1999CLF22121.
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La microbiologie previsionnelle a pour but de decrire par des modeles la croissance de micro-organismes en fonction de facteurs tels que la temperature, le ph et l'activite de l'eau. Nous nous sommes interesses a l'application des modeles de prediction de croissance de pseudomonas species elabores a partir de donnees obtenues en milieu liquide pour la prediction de la croissance dans des aliments solides. Trois souches representatives de pseudomonas species ont ete choisies pour l'elaboration des modeles : p. Fragi 162, de croissance rapide et p. Fragi k1, de croissance lente parmi les p. Fragi ainsi que p. Fluorescens 58, souche de croissance lente. Les modeles ont ete developpes a partir des donnees de croissance obtenues dans les 16 conditions d'un plan central composite (temperature de 2 a 14c, ph de 5,4 a 7 et a#w de 0,96 a 1). Les modeles ont ete valides par des experiences en milieu liquide puis par des experiences de croissance de souches pures en surface de viande decontaminee. Nous n'avons pas trouve de difference significative entre les croissances en milieu liquide et en milieu solide. Le choix des souches s'est revele satisfaisant car les courbes de croissance de pseudomonas species obtenues en viande hachee et en surface de viande ont pu etre predites par les modeles des trois souches.
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Prothiwa, Michaela [Verfasser]. "Inhibition of Quinolone Biosynthesis in Pseudomonas aerugionsa and Burkholderia species / Michaela Prothiwa." Konstanz : KOPS Universität Konstanz, 2019. http://d-nb.info/1237222036/34.
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Kennedy, Enyioha. "Mutability and survival of Pseudomonas aeruginosa in multi-species drinking water biofilm communities." Thesis, University of Southampton, 2012. https://eprints.soton.ac.uk/336439/.
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Pseudomonas aeruginosa is an important opportunistic pathogen of humans and also has the ability to form biofilms in drinking water. However, the survival, persistence and the control of this pathogen within mixed-species bacterial communities in drinking water distribution systems remains poorly understood. Strains of P. aeruginosa obtained from natural and pathogenic biofilms are often hypermutable due to defective DNA error repair systems. However, the role of mutation in determining survival and fitness of P. aeruginosa within the environment has not been explored. This work, investigated the mutability, persistence and survival of hypermutable mutS, wild type and environmental strains of P. aeruginosa within mixed species drinking water consortia and the effects of oxidative stress and water treatment practices including chlorination and UV irradiation on their mutability and persistence within these biofilms using a flow cell continuous culture system. Our results show that P. aeruginosa hypermutator strains integrated and persisted within the biofilm more readily than the wild type and environmental strains. Moreover, growth of P. aeruginosa within a multi-species biofilm led to a 5-fold increase in the mutation frequency (resistance to rifampicin, RifR) of the wild type strain compared to monospecies P. aeruginosa biofilms, suggesting that interactions within polymicrobial communities may promote genetic diversification. Our results also show that antioxidants (L-proline and N-acetyl-cysteine) had an average of 4-fold reduction effect in the mutation frequency of the wild type P. aeruginosa within the mixed species biofilms. However, the mutation frequency exhibited by the mutS strain within the biofilms is independent of oxidative stress. UV irradiation of P. aeruginosa cells, but not exposure to chlorine, led to increases in P. aeruginosa RifR mutation frequency and enhanced the persistence of surviving P. aeruginosa cells within drinking water biofilms. These findings therefore have provided new insights into mechanisms by which drinking water biofilms may harbour important pathogenic micro-organisms and how these interactions within the multispecies biofilms can enhance genetic adaptation and evolution of microbial pathogens.
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Auger, Christopher. "Biochemical Adaptations in Pseudomonas fluorescens Exposed to Nitric Oxide, an Endogenous Antibacterial Agent." Thesis, Laurentian University of Sudbury, 2014. https://zone.biblio.laurentian.ca/dspace/handle/10219/2203.
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Nitric oxide (NO), a free radical released by macrophages (a subset of white blood cells) as a response to infection, is noxious to organisms due to its ability to disable crucial biomolecules such as lipids, proteins and DNA. Although normally effective at eradicating invading bacteria, several pathogens have developed mechanisms to detoxify NO and its toxic by-products, reactive nitrogen species (RNS). While some of these detoxification processes have been characterized, very little is known about the metabolic changes that enable microbes to survive this deleterious environment.
Investigations into the effects of RNS on microbial physiology have shown that these harmful radicals inactivate the citric acid cycle and oxidative phosphorylation, the series of reactions responsible for making energy aerobically. The central aim of this thesis was to determine how the organism counteracts the detrimental effects of RNS, while bypassing the ineffective central metabolic pathways. The findings presented herein show that P. fluorescens engineers an elaborate metabolic network to generate ATP whilst withstanding the injurious effects of nitrosative stress. Crucial to this adaptation is the ability to produce energy via substrate level phosphorylation, a necessity that arises out of the cells’ inability to produce a substantial amount of ATP using the electron transport chain (ETC).
The up-regulation of the enzymes citrate lyase (CL), phosphoenolpyruvate carboxylase (PEPC) and pyruvate, phosphate dikinase (PPDK) helps the organism accomplish this feat. Blue native polyacrylamide gel electrophoresis (BN-PAGE), high performance liquid chromatography (HPLC) as well as co-immunoprecipitation (CO-IP) studies were applied to demonstrate that these proteins form a metabolon, a transient complex of enzymes that ensures citrate is converted into its desired end products, pyruvate and ATP. In order to gauge the individual contributions
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of phosphoenolpyruvate-dependent kinases, a novel in-gel activity assay was developed to probe these enzymes under disparate conditions.
These results suggest that the organism switches from an ATP-dependent metabolism to one based on the utilization of pyrophosphate (PPi). The rationale for this appears to be energy efficiency, as pyrophosphate-dependent glycolysis can theoretically produce five ATP rather than the two yielded by Embden-Meyerhof glycolysis. Additionally, the up-regulation in activity of the enzymes adenylate kinase, nucleoside diphosphate kinase and acetate kinase seem to ensure that ATP generated by PPDK is properly shuttled and stored when aerobic metabolism is defective. The lower activity of inorganic pyrophosphatase likely ensures an adequate supply of pyrophosphate for the activity of PPDK.
Taken together, this research reveals the critical role metabolism plays in the survival of microbes under the onslaught of NO and RNS. As several of these enzymes are absent in mammalian systems, they present themselves as novel targets for the development of new antibacterial agents. A comprehensive awareness of bacterial defense systems in response to NO may lay the groundwork to developing more effective treatments to impede microbial infections.
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Diaz, Benjamin. "STUDIES RELATING PQQ BIOSYNTHESIS TO PUTATIVE PEPTIDASES AND OPERON STRUCTURE IN PSEUDOMONAS SPECIES." UKnowledge, 2017. http://uknowledge.uky.edu/pss_etds/95.
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Several bacteria isolated from the broccoli rhizosphere were assayed to compare their ability to solubilize phosphate and release pyrroloquinoline quinone (PQQ) into the surrounding media. Subsequently, their genomes were sequenced and analyzed for PQQ biosynthesis operon structure. PQQ biosynthesis genes pqqA-F were found in all isolates. The order of PQQ biosynthesis genes and predicted amino acid sequences were compared to each other and the host’s ability to solubilize phosphate and release PQQ. In all Pseudomonas species, two putative protease genes, pqqF, and pqqG, flanked the canonical pqqA-pqqE biosynthesis operon. No mechanistic studies have confirmed the function of pqqF and pqqG.
Pseudomonas putida KT2440 is a versatile model organism, representing environmental, agronomical, and industrial interests. Like the broccoli isolates, P. putida KT2440 biosynthesizes and releases PQQ into its surroundings. To better understand their functions within PQQ synthesis in P. putida KT2440, ∆pqqF, ∆pqqG, and ∆pqqF/∆pqqG strains of P. putida KT2440 were generated and the resulting phenotypes were studied.
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Siciliano, Steven Douglas. "Associations of Pseudomonas species and forage grasses enhance degradation of chlorinated benzoic acids in soil." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ27430.pdf.
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Pritchard, Ian. "Potential inter-relationships between the dissimilatory pathways of steroids and aromatic compounds in Pseudomonas species." Thesis, Liverpool John Moores University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337861.
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Mkono, Yonela Pelokazi. "Evaluation of some pseudomonas species isolated from Hogsback forest reserve for the production of antibacterial compounds." Thesis, University of Fort Hare, 2017. http://hdl.handle.net/10353/5961.
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Pseudomonas species are Gram-negative bacteria most abundant in soil and water bodies, with the capacity to thrive in varied environments. They are largely associated with resistant pathogenic bacteria linked to human and plant diseases. Species such as Pseudomonas aeruginosa have been particularly targeted as case studies due to the extremity to which they pose a threat to human health. With more focus directed at using these species for biocontrol and bioremediation purposes, their role in bioactive compound production may be equally important. As the crisis on antimicrobial resistance still persists, the need for effective antimicrobial compounds is ever more urgent and solutions may possibly still be dormant in bacterial species whose potential has not been fully investigated. On a bid to source out potential antimicrobial compound producers, soil samples were collected from Hogback forest reserve in the province of the Eastern Cape, South Africa. For bacterial screening, M1 and R2A agar were used and the cultures grown at 37˚C for a period of seven days. After the presumed Pseudomonas species were identified, antimicrobial production was determined by submerged fermentation method using nutrient broth as media of choice. Active isolates were further studied to determine the optimum conditions which best facilitate for antimicrobial compound production, with parameters such as temperature (25˚C – 40˚C) and pH (4 – 9) considered. The role plasmids play in antimicrobial compound production was also investigated. Each isolate was grown in fermentation media containing Sodium dodecyl sulphate and Ethedium Bromide, at varying concentrations, to facilitate for plasmid curing. With each sample, distinct colonies were identified with varying pigmentations most dominant being a cream colour. The identity of the isolated strains was achieved through sequencing of 16S rDNA. Phylogenetic analysis showed that isolate A16 had 80 percent homology with Pseudomonas plecoglossicida strain P4 and share a close ancestor with isolates Y52 and Y81, also isolate Y89 showed a 90 percent homology with Pseudomonas sp. Co-11a. With the exception of isolate A16, the isolates which were active against Gram-negative bacteria lost activity as the screening processes continued. When looking at temperature variations, isolates Y81 and A16 were highly active with maximum activity observed at 35˚C while Y89 performed best at 25˚C and Y52 showed constant activity across all studied temperatures. The plasmids in all isolates were found to be 48.5 kb in size with the exception of isolate Y89 which was 20 kb. The plasmids were cured at concentrations of (1 mg/ml; 5 mg/ml; 7 mg/ml; 10 mg/ml; 11 mg/ml) SDS and (125 μg/ml; 6.5 μg/ml; 5μg/ml) EtBr. The curing process also showed changes in both the antimicrobial activity of the isolates as well as their physical characteristics. The isolates are the first reported Pseudomonas species from Hogsback forest reserve with the ability to produce antimicrobial compounds which are active against Gram-positive and Gram-negative bacteria. These mesophilic bacteria also show that plasmids do not pay any role in the production of antimicrobial compounds and that the biosynthesis genes are highly likely to be chromosomal borne meaning that the production cannot be linked to horizontal transfer of genes. Therefore, these isolated Pseudomonas species provide a potential reservoir of antimicrobial compounds which may play an important role in the antimicrobial resistance phenomenon.
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Chierici, M. "INVESTIGATION ON THE BLUE PHENOTYPE IN PSEUDOMONAS SPECIES INVOLVED IN BLUE DISCOLORATION DEFECT OF FRESH CHEESE." Doctoral thesis, Università degli Studi di Milano, 2016. http://hdl.handle.net/2434/412117.
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La presenza di macchie di colore blu su Mozzarella è una problematica attuale per le industrie produttrici di questa tipologia di formaggio fresco. In particolare dal 2010 sono stati segnalati diversi casi in Italia con grande risalto nei notiziari nazionali ed europei, causando anche una segnalazione da parte del sistema di allerta RASFF. La causa della formazione del colore blu è stata identificata nella contaminazione di ceppi appartenenti al genere Pseudomonas.
Per questo lavoro di tesi di dottorato è stata costituita una collezione di 69 isolati appartenenti al genere Pseudomonas (elencati nel capito Appendix 1): di questi, 59 sono stati isolati da campioni di Mozzarella con difetto blu e identificati mediante sequenziamento della regione 16S rRNA. La produzione del pigmento blu è stata confermata incubando gli isolati nel liquido di governo di Mozzarella, precedentemente centrifugato e sterilizzato per filtrazione 0.22 µm (PF), a 4°C. Trenta campioni diventarono blu dopo 7 giorni (33.7% degli isolati). Su tutti gli 89 ceppi è stata fatta la restrizione del genoma usando l’enzima SpeI seguita dalla corsa elettroforetica in campo pulsato (PFGE) per valutare un’eventuale correlazione genetica tra gli isolati produttori del pigmento blu. Dai profili ottenuti i 30 isolati presentati il fenotipo blu sono stati raggruppati in 12 genotipi. Per ogni genotipo è stato scelto un ceppo rappresentativo su cui è stata fatta una tipizzazione attraverso il sequenziamento di 7 loci conservati (MultiLocus Sequence Typing) per confermare l’esistenza di una relazione filogenetica comune ai ceppi produttori del blu. Per 3 ceppi produttori del blu (200188/6, UMB247, UMB248) è stato sequenziato l’intero genoma. Le sequenze dei genomi ottenuti sono state confrontate con quelle di altri 2 ceppi produttori del blu (PS77 e PS22) e di 5 ceppi non presentanti la formazione del pigmento blu (PS40, PS20, Pf01, A506, SBW25). Da questa analisi di comparazione dei genomi è stata individuata una regione di circa 10 kbp presente unicamente nei genomi dei ceppi produttori del blu, composta da 13 CDS, la maggior parte delle quali (53.7%) codificante per proteine costitutive di batteriofagi. Per indagare la relazione tra la presenza di profagi integrati nel genoma dei ceppi produttori del blu e lo sviluppo di questo particolare fenotipo, i 30 isolati produttori del blu sono stati sottoposti a induzione con due diversi antibiotici (norfloxacina e ciprofloxacina). La presenza di batteriofagi indotti dal trattamento con gli antibiotici è stata verificata misurando un’eventuale attività inibente sulla crescita di ceppi produttori del blu di Pseudomonas spp., seguita dalla conferma mediante spot test e isolamento con la formazione di placche di lisi in doppio strato di agar. Alcuni campioni che hanno causato una zona di lisi negli spot test sono stati fotografati con microscopio elettronico a trasmissione. Attraverso le immagini sono state individuate due tipologie di particelle virali esclusivamente nei campioni indotti con ciporfloxacina. Non è stato però possibile procedere all’isolamento dei batteriofagi in quanto non sono state ottenute singole placche di lisi.
L’altra tematica affrontata durante questo progetto di dottorato è stata l’identificazione della/e molecola/e blu e del suo ruolo nell’ambiente. Per determinare i requisiti necessari per la produzione del pigmento blu sono state allestite delle prove fenotipiche in liquido di governo a tre diverse temperature (4°C, 14°C e 30°C) e in terreno minimo M9 a diversi pH (5.7, 6.3, 7.2) addizionato con (a) differenti fonti di carbonio (lattosio, glucosio, galattosio, acido lattico e acido succinico), (b) diversi metalli (Mo, Cu, Zn, Ca, Mg, Bo, Co, Mn, Fe) e (c) 18 diversi amminoacidi. La produzione del pigmento blu è stata osservata solo quando i campioni sono stati incubati a temperature di refrigerazione (al di sotto dei 14°C) in liquido di governo o nel terreno minimo a pH 5.7. La presenza di Cobalto e di alcuni amminoacidi, ad esempio la lisina, hanno avuto un effetto inibente sulla produzione del pigmento blu, mentre l’aggiunta di prolina ne ha aumentato l’intensità. L’analisi UPLC/MS dei campioni 200188/6, UMB247 e UMB248 in liquido di governo e dei campioni in M9 + prolina non ha portato all’identificazione univoca della/e molecola/e che danno la colorazione blu. Per comprendere la funzione del pigmento blu sono state verificate una possibile correlazione con i segnali di quorum sensing e un possibile ruolo come batteriocina. I segnali di quorum sensing non sono risultati legati alla produzione del blu, mentre per quanto riguarda l’attività batteriostatica è risultato che, al contrario delle aspettative, il pigmento blu possiede un effetto positivo sulla crescita dei ceppi blu di Pseudomonas spp..In 2010 the occurrence of blue spots on Mozzarella cheese was reported from several consumers in Italy and highlighted by local and international media and by RASFF alert system (RASFF Annual Report 2010). P. fluorescens spp. was identified as the causing agent of this blue pigmentation. In this phD thesis work a collection of about 69 Pseudomonas spp. isolates (listed in Appendix 1) was used: from these 59 were isolated from spoiled samples of Mozzarella cheese presenting the blue coloration defect and identified by 16S rDNA sequencing. The production of the blue pigment was confirmed by incubation of the isolates in Mozzarella Preserving Fluid (PF) centrifuged and sterilized by filtration 0.22 µm; incubation was made at 4°C. The medium turned blue after 7 days in 30 samples (33.7% of the isolates). To investigate the genetic relationship between blue pigment-producing and blue pigment not-producing isolates, genome restriction was performed using SpeI enzyme, coupled with pulsed gel field electrophoresis (PFGE). From bands profile it was seen that the 30 blue producing isolates were grouped in 12 genotypes. From each genotype one representative strain was chosen for MultiLocus Sequence Typing analysis (MLST) to confirm a phylogenetic relationship among the blue pigment-producing strains. For 3 blue pigment-producing strains (200188/6, UMB247 and UMB248) the whole genome was sequenced and compared with 2 further blue pigment-producing strains genome (PS77 and PS20) and with the genomes of 5 blue pigment not-producing strains (PS40, PS20, Pf01, A506, SBW25). From this comparison a unique region of about 10kbp present in the blue pigment-producing strains and not shared by the blue pigment not-producing strains was found. This region is composed by 15 CDS, most of them (53.7%) coding for phage related elements. To investigate the relationship between the presence of prophages and the development of the blue phenotype the 30 blue pigment-producing isolates were induced by two different antibiotics (norfloxacin and ciprofloxacin). The presence of induced bacteriophages was assayed by measuring an inhibitory effect on the growing curves of blue pigment-producing Pseudomonas spp., by spot test assay and by plaques formation on double layer agar. For samples with a positive result from spot test, TEM photographs were made, showing two phage morphologies from a sample induced by ciprofloxacin. It was not possible to isolate these phages because they were not plaque producing. The other main topic of this job was the identification of the blue pigment and of its role in the ecology of P. fluorescens. To determinate the environmental requirement for its production several assays were made incubating the blue strains in PF at different temperature (4°C, 14°C and 30°C) and in M9 minimal medium at different pH (5.7, 6.3, 7.2) with (a) different carbon source (glucose, galactose, succinic acid, lactic acid), (b) different metals (Mo, Cu, Zn, Ca, Mg, Bo, Co, Mn, Fe) and (c) 18 different amino acids. From these phenotypic tests it resulted that the blue production occurred only at refrigeration temperature (lower than 14°C) in medium with pH 5.7. The presence of Cobalt or lysine inhibited the blue synthesis, while it was increased when proline was present. The individuation of the blue molecule/s from blue samples of PF and M9+proline incubated with strains 200188/6, UMB248 and UMB254 was made by UPLC/MS without leading to a definitive result. Trying to identify the function of the blue molecule/s, its possible connection with quorum sensing signals and its role as bacteriocine were investigated. Quorum sensing signals were found not to be related with blue production; as for the bacterial growth inhibiting effect it was noticed that the presence of the blue molecule/s, contrary of what expected, was able to promote the growing of Pseudomonas spp.
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Cossali, Giovanna. "A fundamental design study of electrochemical processes for the control of pathogenic bacteria." Thesis, Brunel University, 2015. http://bura.brunel.ac.uk/handle/2438/13748.
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Water systems in buildings have been reported to contribute to pseudomonal infection transmission and have been associated with Legionnaires’ disease (LD) outbreaks, for they provide the perfect conditions for bacteria proliferation and biofilms formation. An overview of the problem has highlighted that the economic burden, the healthcare and mortality costs of both LD and pseudomonal infections are significant. Although critical to the safe delivery of water, pathogen control continues to remain a challenge as current hot water treatments are not always effective, are often energy intensive and require expensive maintenance. This thesis was set out to evaluate the potential use of electrochemical disinfection (ED) in controlling pathogens in hot water systems of buildings. In this project, we performed a fundamental systematic study on the effect of geometrical and operational parameters in a flask, to gather an understanding of the effect of each parameter on the rate of bacteria elimination, crucial for the design and optimization of electrolytic cells. ED prototypes were then installed in in the hot water systems of two different buildings operating at 60°C, the temperature recommended for Legionella control (HSE, 2013), and their efficacy was monitored long term. In one of the buildings, 2 to 4– log reductions in total bacteria counts was observed, while Pseudomonas species counts were reduced by 3 log. The apparent failure in the other building was due to the inadequate operation of the water system. In order to achieve the 2019 zero carbon targets for new non-domestic buildings set by the UK government, the energy demand associated with heating water needs to be addressed, but maintaining systems at such high temperatures renders difficult the use of greener technologies that could further reduce the CO2 impact of heating water. Given that ED generates disinfectants and that the Health and Safety Executive advises that if hot water is treated with biocides, water temperatures can be reduced, the efficacy of the prototype device was evaluated under laboratory conditions at temperatures between 30 and 45˚C. The prototype was found to be effective both on laboratory-grown biofilm and on planktonic Legionella pneumophila serogroup 1, with 5-log reduction on bacteria counts.
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Kassen, Rees M. "Experimental studies on the fate of diversity in heterogeneous environments." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=36966.
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Environmental heterogeneity has often been suggested as a general explanation for patterns of diversity at scales ranging from individuals within populations to communities within landscapes. I evaluate this proposition using laboratory experiments with two microbial species, the unicellular chlorophyte Chlamydomonas reinhardtii and the common bacterium Pseudomonas fluorescens. These experiments contrast the fate of diversity following selection in heterogeneous and homogeneous environments. Specifically, I show that (1) an individual's breadth of adaptation evolves to match the amount of environmental variation, specialists evolving in environments that remain constant through time and generalists evolving in environments that vary through time irrespective of the scale at which environmental variation occurs relative to the lifetime of an individual; (2) the maintenance of diversity in a spatially heterogeneous environment is context-dependent, diversity being more readily maintained when environmental conditions are very different and genotypes are widely divergent; (3) selection in heterogeneous environments represents a plausible mechanism for two well-known patterns of diversity at large spatial scales, namely that between species diversity and both productivity and disturbance. This thesis thus demonstrates that environmental heterogeneity is a plausible, and perhaps very general, factor responsible for the diversity of natural communities.
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Heck, Marcela Georgia [Verfasser], and Kenneth Nigel [Akademischer Betreuer] Timmis. "Functional biodiversity of Pseudomonas species in biofilm communities degrading polycyclic aromatic hydrocarbons / Marcela Georgia Heck ; Betreuer: Kenneth Nigel Timmis." Braunschweig : Technische Universität Braunschweig, 2011. http://d-nb.info/1175826103/34.
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Hotta, Gou. "Risk factors and outcomes of Stenotrophomonas maltophilia bacteraemia: a comparison with bacteraemia caused by Pseudomonas aeruginosa and Acinetobacter species." Kyoto University, 2015. http://hdl.handle.net/2433/199197.
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El, Amin Nagwa Mustafa. "Studies on the molecular mechanisms of resistance to fluoroquinolones and carbapenems in selected bacterial species /." Stockholm, 2003. http://diss.kib.ki.se/2003/91-7349-646-4/.
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Malhotra, Sankalp. "Immune evasion tactics and immunopathology of mixed mucoid and nonmucoid Pseudomonas aeruginosa populations in cystic fibrosis." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1524156292309518.
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Frapwell, Connor. "Phenotypic and genotypic characterisation of single and dual species biofilms of Pseudomonas aeruginosa and Staphylococcus aureus treated with a novel antimicrobial compound." Thesis, University of Southampton, 2018. https://eprints.soton.ac.uk/427306/.
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Bacterial infections are becoming increasingly difficult to treat due to the emergence of antimicrobial resistance, (AMR), which renders current antimicrobial therapies ineffective. Further complicating matters is the ability of bacteria to form communities called biofilms, which are infamous for their tolerance to antimicrobial therapy. Biofilm mediated tolerance and AMR contribute to disease chronicity. Consequently, there is a need for novel antimicrobial interventions. The aim of this thesis was to characterise a novel antimicrobial, HT61, against biofilms of clinically relevant bacterial pathogens, particularly Pseudomonas aeruginosa and Staphylococcus aureus. Phenotypic studies showed that HT61 was effective against biofilms formed by Gram-positive species with limited efficacy towards biofilms of Gram-negative species. Scanning electron microscopy of HT61 treated biofilms of S. aureus and P. aeruginosa suggested a mechanism of action targeting the cell envelope. Quantitative proteomic analysis of HT61 treated S. aureus cultures supported this, identifying upregulation of proteins associated with the cell wall stress stimulon and division cell wall cluster. To investigate the effect of interspecies interactions on bacterial adaptation to HT61, a dual species biofilm model of P. aeruginosa and S. aureus was developed and characterised. Fluctuation analysis suggested that biofilm co-culture increased the mutation rate of S. aureus over 500-fold compared to planktonic culture and almost 100-fold compared to culture as a single species biofilm. Whole genome sequencing of single and dual species biofilm derived P. aeruginosa and S. aureus isolates revealed significant genomic variation in both coding and intergenic sequences, but no change in evolutionary trajectory between isolates derived from mono- or co-culture biofilms. Following HT61 treatment, mutations in S. aureus were identified in graS and fmtC, which encode products that modulate the cell envelope and may suggest routes to HT61 adaptation. In summary, the data presented in this thesis suggests potential mechanisms of action and adaptation to HT61, which could inform future antimicrobial development. This thesis also reinforces the need to understand the impact of interspecies interactions on bacterial evolution and shows that biofilms are important hubs of genomic diversity, which could have dangerous implications for the emergence of AMR.
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Martin, Dana. "Investigation of the Biocontrol Activity in vitro and in planta of Different Pseudomonas Species Against Important Crown, Stem, Foliar and Root Pathogens of Ornamental Crops." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1503063395390704.
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Hutcheon, Carolyn Jamie. "Active oxygen species accumulation in the immunization and manifestation stages of systemic acquired resistance during an arabidopsis thaliana-pseudomonas syringae pv tomato interaction." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0022/MQ40696.pdf.
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Morais, Cristiana Carvalho. "Production of bacterial biopolymers from industrial fat-containing wastes." Master's thesis, Faculdade de Ciências e Tecnologia, 2013. http://hdl.handle.net/10362/10922.
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Dissertation presented in partial fulfilment of the Requirements for the Degree of Master in BiotechnologyPolyhydroxyalkanoates (PHAs) constitute a group of biobased and biodegradable polymers, which have been recognized as good substitutes for petroleum-based polymers in many applications. The large-scale production of PHAs is limited by the high cost of the most commonly used carbon sources (e.g. glucose, sucrose). However, the food industry generates large amounts of wastes, including fat-containing materials that can be used as low cost carbon sources for microbial cultivation, due their high carbon content. In this study, several bacterial strains (Cupriavidus necator, Comamonas testosteroni, Pseudomonas oleovorans, P. resinovorans, P. stutzeri, and P. citronellolis) were evaluated for their ability to grow and produce PHAs using fat-containing wastes generated by the food industry. The materials used in this study were mainly composed of free fatty acids, namely mystiric, oleic, linoleic and stearic acid. In the preliminary shake flask experiments, C. necator, C. testosteroni, P. oleovorans and P. citronellolis were able to grow and produce PHA polymer on margarine waste with the highest content. Those strains were selected for batch bioreactor experiments, wherein C. necator reached the highest polymer content (56%, wt/wt) and volumetric productivity (0.33 gPHA/L.h), Lower PHA contents were achieved by P. citronellolis and P. oleovorans (7.0 and 8.5%, wt/wt, respectively). However, in contrast with C. necator that synthesized polyhydroxybutyrate [P3(HB)], those strains produced medium chain length polyesters (mcl-PHA) containing monomers of 3-hydroxyoctanoate (HO) and 3-hydroxydecanoate (HD). C. necator was also cultivated in two different fed-batch strategies. The first cultivation achieved 76% (wt/wt) of P(3HB), while high cell densities were obtained in the second cultivation (48 g/L of active biomass concentration). Finally, the P(3HB) and mcl-PHA polymers had a glass transition temperature of 0.5–7.9ºC and -45.6, a melting point of 169.3–173.4ºC and 60.9ºC, and degree of crystallinity of 48.7–56.6% and 0.7%, respectively.
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Ngo, Van Hai. "Use of customised probiotics for western king prawn (Penaeus latisulcatus Kishinouye, 1896) culture." Thesis, Curtin University, 2009. http://hdl.handle.net/20.500.11937/1691.
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In recent decades, a rapid increase in fish production from the aquaculture sector has led to degradation of the environment due to indiscriminate use of chemical additives and veterinary medicines. Consequently, antimicrobial resistance among pathogenic bacteria has increased and environmental problems associated with these chemicals and antibiotics have become a burden for sustainable aquaculture development. Therefore, there is a need to alter the indiscriminate use of chemicals and antibiotics for the use in aquaculture by replacing these with prebiotics or other harmless substitutes. Different probiotics can confer huge functions and benefits to various hosts through the improvement in survival rates and enhancement of health. However, there is a need for special species-specific prebiotics in a particular culture environment.Customising the species-specific probiotics for prawn culture was performed via several experiments. After the specific prebiotics, Pseudomonas synxantha and P. aeruginosa were isolated and tested from a commercial product, the emphasis was on determining the effectiveness of them on the cultivation of the juveniles’ western king prawns, Penaeus latisulcatus. The customisation process began with trialling five inhibition test methods to determine the most effective detection method for the potential probiotic bacteria. P. synxantha and P. aeruginosa showed the highest inhibition against Vibrio spp. isolated from P. latisulcatus and pathogenic Vibrio isolated from other aquatic animals.A series of experiments were conducted under laboratory conditions to investigate the physiological and immune responses of the juvenile P. latisulcatus exposed to the customised probiotics. The research results proved the suitability of these probiotics for the cultivation of P. latisulcatus as they conclusively met all the essential requirements for the appropriate probiotics. The application of these customised probiotics at 10[superscript]5 CFU/mL as “water additives” or “feed supplements” improved the specific growth rate, survival and the health of juvenile P. latisulcatus. These customised probiotics showed similar beneficial effects as observed with other commercial prebiotics, Bio-Mos[superscript]® and ß-1,3-D-glucan. The supplementation of these probiotics with the formulated feed was more efficacious and more practical than direct application into the rearing media. The prawns exposed to the combined probiotics were healthier than those exposed to the individual probiotics. In addition, P. aeruginosa was more effective than P. synxantha for improving prawn health.P. latisulcatus were not adversely affected by the customised probiotics, as P. latisulcatus grew well in the presence of a high probiotic density of 10[superscript]7 CFU/mL. The application of the probiotics however, reduced the negative effects of the pathogen V. harveyi as the probiotic-fed prawns survived 100% when they were exposed to V. harveyi at 10[superscript]5, 10[superscript]7 and 10[superscript]3 CFU/mL for 24, 24 and 36 h, respectively. Hence customised probiotics are suggested as an alternative to antibiotic for disease control in prawn aquaculture. The prawn survival was also influenced by the concentrations of the pathogen and duration of the challenge. At a challengeconcentration of 10[superscript]3 CFU/mL of V. harveyi, the 100% survival-hours were shorter (12 h) in the control group (prawns not fed with probiotics) than in the probiotic-fed prawns (36 h). Further, prawns not fed with probiotics died at a faster rate (96 h) than the probiotic-fed prawns (156 h). The prawns died when the exposure to V. harveyi (even at 10[superscript]3 CFU/mL) was longer than 36 h. The probiotic-fed prawns could not completely resist the pathogenic effects of the V. harveyi despite the detection of the probiotics in the intestine of the prawns earlier than detection of V. harveyi. It is recommended that these customised probiotics can be used as a substitute to antibiotics in the cultivation of western king prawns.
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Smith, Catherine J. "Production of a lipase from a Pseudomonad species." Thesis, Cranfield University, 1991. http://dspace.lib.cranfield.ac.uk/handle/1826/4183.
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A lipase-producing micro-organism was found to be a strain of Pseudomonas aeruginosa. When it was grown batchwise in a stirred 2 dM3 fermenter in a simple defined minimal salts medium containing yeast extract and glucose, it produced lipase at a level of 0.173 LU/cm3 without the need for a lipid substrate. Batch cultures of cells were fed glucose at constant rates. An optimum rate was found to be 0.50 g/dm3/h and this produced a maximum lipase activity of 0.80 LU/cm3. Medium composition was changed until it was possible to produce 25 g/dm3 dry weight of cells. Evidence of linear growth due to nutient, limitations was obtained. A microcomputer controlled protocol was used successfully to feed glucose solutions at exponentially increasing rates. Problems were encountered with the production of lipase from the interaction with pyocyanin production and from possible trace nutrient limitations.
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Rondet, Damien. "Caractérisation d'une nouvelle voie de signalisation impliquée dans la défense stomatique et applications agronomiques." Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0083.
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La défense pré-invasive ou stomatique est un mécanisme qui consiste en la fermeture des pores stomatiques présents sur les organes aériens des plantes lorsque celles-ci sont en contact avec certains agents pathogènes. Cette fermeture empêche ces derniers de pénétrer dans l’hôte et de le coloniser. Ce mécanisme s’active chez Arabidopsis inoculée par la bactérie Pseudomonas syringae pv tomato (Pst) DC3000. Des travaux préliminaires de notre groupe avaient montré que la carbonylation de protéines cibles par des espèces réactives électrophiles (EREs) représentait une étape cruciale de la signalisation cellulaire nécessaire à la mise en place de cette défense. Par des approches de marquage ciblé et de purifications couplées à des identifications par spectrométrie de masse en tandem (nanoLC-MS/MS), nous avons pu caractériser une sérine-thréonine protéine kinase qui joue un rôle déterminant dans ce mécanisme de défense. En effet, des plantes mutées sur le gène codant cette protéine ont perdu la capacité à induire la fermeture de leurs stomates et à déployer la défense stomatique vis-à-vis de la bactérie. De plus, l’introduction de la chimie click (cycloaddition alcyne-azide catalysée par le cuivre), dans nos approches de marquage, nous a permis d’identifier un ensemble de protéines très probablement carbonylées et susceptibles de jouer un rôle crucial dans ces évènements cellulaires qui contribuent à une part de l’immunité végétale. Enfin, les EREs étant capables d’induire la fermeture des stomates, nous avons cherché à savoir, dans le cadre de l’établissement d’une preuve de concept, si leur application sur des plantes permettrait la protection de ces dernières contre PstPre-invasive or stomatal defense is a mechanism which consists of closing the stomata present at surface of aerial organs of plants when they are in contact with certain pathogens. This closure prevents them from entering and colonizing the host. This mechanism is activated in Arabidopsis inoculated by the bacterium Pseudomonas syringae pv tomato (Pst) DC3000. Preliminary work by our group had shown that carbonylation of target proteins by reactive electrophile species (RES) was a crucial step of the cell signaling required to set up this defense. Through targeted tagging and purifications approaches coupled with tandem mass spectrometry identifications (nanoLC-MS/MS), we have been able to characterize a serine-threonine protein kinase that plays a crucial role in this defense mechanism. Indeed, plants mutated on the gene encoding this protein have lost their ability to trigger stomatal closure and to deploy the stomatal defense against the bacteria. In addition, the use of the click chemistry and notably, the copper-catalyzed alkyne-azide cycloaddition, in our tagging approaches has enabled us to identify a set of proteins that are most likely carbonylated and likely to play a significant role in these cell events that contribute to part of plant immunity. Finally, since RES are able to induce stomatal closure we sought to find out, in the context of establishing a proof-of-concept, whether their application to plants would enable them to be protected against the Pst
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Kellman, Anthony W. "Rhizobium inoculation, cultivar and management effects on the growth, development and yield of common bean (Phaseolus vulgaris L.)." Diss., Lincoln University, 2008. http://hdl.handle.net/10182/378.
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Genotypic differences in growth and yield of two common bean (Phaseolus vulgaris L) cultivars to Rhizobium inoculation and management were investigated. In 2003-04, the two bean cultivars (Scylla and T-49) were combined with three inoculant treatments (strains CC 511 and RCR 3644, and a control of no inoculation), two fertiliser levels (0 and 150 kg N ha⁻¹) and two irrigation treatments (irrigated and rainfed). There was no nodulation on either cultivar. To further investigate the symbiotic relationship, 16 rhizobial isolates, including the two used in the first field experiment, were combined with the cultivar Scylla and evaluated in a greenhouse. Subsequently, five Rhizobium isolates were chosen for further field evaluation, based on signs of early nodulation in the greenhouse trial. The second field experiment in 2004-05 combined the five inoculant strains (RCR 3644, UK 2, H 20, PRF 81, PhP 17 and a control) with two bean cultivars (Scylla and T-49). In the greenhouse, nodule number varied from 7 (UK 2) to 347 (H 441) nodules plant⁻¹ at 51 DAS and from 13 (UK 1) to 335 (CIAT 899) nodules plant⁻¹ at 85 DAS. In 2004-05, in the field, nodulation was also variable, ranging between 1 and approximately 70 nodules plant⁻¹, with higher nodules numbers plant⁻¹ being found on cultivar T-49. Of the isolates used in the field, strains H 20, PRF 81 and PhP 17 produced 70, 25 and 12 nodules plant⁻¹ at 70, 40 and 54 DAS respectively. Nodules formed were of various sizes and more than 80 % were pink to dark red in colour denoting the presence of leghaemoglobin and active N fixation. The remaining nodules were either green or white. The importance of selecting an appropriate cultivar for the growing conditions was highlighted in these experiments. Leaf area index, leaf area duration intercepted radiation and final utilisation efficiency were significantly affected by cultivar. In both seasons cv. T-49 reached maturity (dry seed) before Scylla, while unirrigated plants reached green pod maturity seven days before irrigated plants. Plants of cv. Scylla gave a final TDM of 730 g m⁻²; compared to the 530 g m⁻² produced by T-49. The average growth rate was 7.0 and 5.2 g m⁻² day⁻¹ for Scylla and T-49 respectively (2003-04). Plants receiving 150 kg N ha⁻¹ produced 665 g m⁻² TDM which was 12 % more than was produced by unfertilised plants. The application of 150 kg N ha⁻¹ gave an average growth rate of 6.4 g m⁻² day⁻¹ compared to 5.7 g m⁻² day⁻¹ from plants with no N. Inoculation in the field had no significant effect on TDM in both seasons. Temperature affected growth and DM accumulation. Accumulated DM was highly dependent on cumulative intercepted PAR. Air temperatures below the base temperature (10 °C) affected growth in 2004-05, resulting in plants accumulating just 0.24 g DM MJ⁻¹ PAR during early growth. This increased to 2.26 g DM MJ⁻¹ PAR when the temperature was increased above the base temperature. There was a strong relationship between LAI and intercepted PAR. A LAI of 4.0-4.5 was required to intercept 90-95 % of incident solar radiation. Cultivar significantly (p < 0.001) affected radiation use efficiency (RUE). Scylla had a RUE of 1.02 g DM MJ⁻¹ PAR compared to T-49 at 1.18 g DM MJ⁻¹ PAR. Seed yield was significantly (p < 0.001) affected by cultivar and fertiliser application. Cultivar Scylla produced 467 g m⁻² which was 76 % more than T-49, while a 12 % increase in seed yield was observed in N fertilised plants over unfertilised plants. Only cultivar significantly affected HI, while the yield components that had the greatest effect on seed yield were hundred seed weight and pods plant⁻¹. Inoculation significantly (p< 0.05) affected 100 seed weight (2004-05). Plants inoculated with strain H 20 had the highest 100 seed weight at 25.2 g with cv. Scylla producing larger seeds than T-49. The belief that local environmental conditions play a major role on field survival of bacteria, led to the use of PCR methods to identify field nodulating organisms. Amplification of genomic DNA from parent isolates using primers fC and rD generated a single band for each isolate. Isolates were identified to the species level as either Rhizobium or Agrobacterium, using the highly conserved internally transcribed spacer (ITS) region and are known to nodulate common bean. The DNA extracted from the isolates recovered from nodules of field grown beans gave multiple bands with primers fC and rD. Five distinct banding patterns were observed. All of these were different from those of parent isolates. Sequencing of the 16S rRNA demonstrated that nodules of field grown beans in Canterbury were inhabited by Pseudomonads either alone or in association with other root nodulating organisms. The inability to identify the inoculant strains in nodules of field grown beans does not rule out their infection and nodulating function in the cultivars used. The results suggest the possibility of both Rhizobium and Pseudomonads cohabiting in the nodules of field grown beans. The aggressive nature of Pseudomonads on artificial media, possibly out competing the inoculant rhizobia is proposed, leading to the inability to identify the inoculant strain from the nodules of the field grown beans by PCR methods. The need to identify the nodule forming or nodule inhabiting bacteria in the nodules is necessary to classify the importance of these organisms and their economic benefit to agricultural production. This study also underlines the importance of using PCR methods to gain valuable insights into the ecological behaviour of Rhizobium inoculants and nodule inhabiting organisms.
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Kasilingham, Rajappan. "Biological control of potato late blight disease caused by Phytophthora infestans using fluorescent pseudomonads and Trichoderma species." Thesis, University of Reading, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.691413.
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Blehert, David S. "Characterization of xenobiotic reductases from two pseudomonas species." 1999. http://catalog.hathitrust.org/api/volumes/oclc/45220711.html.
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Ming-Cheng and 林明正. "The Interaction Mechanism between Nitro Compounds and Pseudomonas Species Lipase." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/49401379073613022197.
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博士中山醫學大學
醫學研究所
95
Purpose : This dissertation embarks to understand the relationships between nitro compounds and the activation of lipase. Thus, the goal of this study is then to characterize interactions between nitro compounds and Pseudomonas Species lipase (PSL) in vitro. Results : PA and styphnic acid are characterized as the mixed-type inhibitors of PSL. From chemical structure point of view, PA and styphnic acid carry hydroxyl groups and make both compounds hydrophilic. Therefore, PA and styphnic acid are capable of entering the hydrophilic active site of Pseudomonas Species lipase and become inhibitors of the enzyme due to the hydrophilic character of both compounds. On the other hand, TNT, RDX, and HNIW are the essential activators of PSL. From chemical structure point of view, TNT, RDX, and HNIW are more hydrophobic than PA and styphnic acid. Therefore, TNT, RDX, and HNIW presumably mix with triton-X 100 and bind to the co-lipase binding site of PSL and become the essential activators of PSL. Moreover, the interfacial activation of PSL by the essential activators in the presence of detergents is proposed according to the lipase-colipase mechanism. Interestingly, HMX and nitroglycerin are neither an inhibitor nor an activator of the enzyme. Therefore, HMX and nitroglycerin do not bind to the active site of PSL due to the hydrophobic characters of HMX and nitroglycerin. Moreover, HMX does not bind to the co-lipase binding site of PSL probably due to a huge dimension of HMX and weak interactions between HMX and detergent triton X-100. With the glycerol backbone, nitroglycerin has more stable conformations than other nitro compounds and therefore it interacts loosely with the detergent. Conclusions : The goal of this work is to determine the enzyme kinetics for Pseudomonas Species lipase catalyzed hydrolysis of substrate p-nitrophenyl butyrate in the presence of nitro compounds such as nitroglycerin, 2,4,6-trinitrotoluene (TNT), picric acid, styphnic acid, hexahydro-1,3,5-trinitrotriazocine (RDX), octahydro-1,3,5,7-tetranitrotriazocine (HMX), and hexanitrohexaazaisowurtzitane (HNIW) in vitro. Kinetically, picric acid and styphnic acid are the mixed-type inhibitors but TNT, RDX, and HNIW are the essential activators of the enzyme in the presence of a detergent triton-X 100. Interestingly, HMX and nitroglycerin are neither an inhibitor nor an activator of the enzyme.
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Lee, Feng-Tsai, and 李豐在. "Expression of Bacillus Chitinase in Pseudomonas Species and its Antifungal Activity." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/62094401741692084805.
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碩士國立臺灣大學
植物病理學研究所
89
Chitin, a -1,4-linked polymer of N-acetylglucosamine, is widely existed in many organisms, including crustances, fungi, nematodes and insect, and is able to protect and support the body of organisms. Many kinds of organisms produce chitinase to cleave -1,4-linkage between N-acetylglucosamines and hydrolyzes the chitin polymer to release N-acetylglucosamine oligomers or monomer. The goal of this study is to screen fluorescent Pseudomonas antagonists from rhizosphere and construct Bacillus chitinase gene-containing Pseudomonas strains. Based on the synergism of chitinase and antibioticts, the biocontrol activity can be enhanced. In order to make fluorescent Pseudomonas translocate Bacillus chitinase to the bacterial cell surface, firstly, the DNA sequence encoding signal peptide and transmembrane domain of OmpA (ST-DNA) was amplified from the genomic DNA of Escherichia coli and ligated with the vector pCR2.1. A Bacillus chiA-containing DNA was amplified from pNTU111 and placed downstream of ST-DNA. The chitinase translocated to the outer membrane of E. coli TOP10F' was assumed. Then, ST-chiA DNA was ligated with the shuttle vector, pMMB6, in the position downstream of tac promoter. In Pseudomonas putida, chitinase activity was apparently detected in membrane fraction, supporting that ompA ST-DNA could drive Bacillus chitinase to outer membrane. In addition, we have isolated thirty-six strains of fluorescent pseudomonads from plant rhizosphere. In the dual culture with Sclerotium rolfsii, different strains of fluorescent pseudomonads showed different antifungal activities. Among these antagonistic Pseudomonas strains, seven was performed biocontrol assay. Three Pseudomonas strains could decrease the diseased incidence on bean after seed-coating with Pseudomonas antagonist. Then, plasmid pMMST2000 was transferred into one of Pseudomonas strain, FP-16, the biocontrol activity of FP-16(pMMST2000) was higher than wild strain, FP-16, however, the biocontrol activity between wild and genetic engineered strain did not show significant difference.
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Ebinesar, J. S. S. Allwin. "Bioremediation of Zinc using Pseudomonas Species - Mechanistic Studies and Biosensor Applications." Thesis, 2016. http://etd.iisc.ac.in/handle/2005/3210.
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The rivers, lakes and seas are the major water sources for the animal and plant kingdom in this earth. In recent times, the usage and wastage of water have been increasing due to the uncontrolled population growth. In addition to that, the rapid industrialization over the years has led to the gradual depletion of the natural resources like water, soil and air. Some of these industries discharge contaminants like organic products and inorganic (or) toxic heavy metals without treatment into the environment, leading to its degradation. Zinc is the 24th most abundant element present in the earth crust, amounting 75 ppm (0.0075%). The concentration of zinc present in the soil and seawater is about 64 ppm and 30 ppb respectively (Emsley, 2001). Generally, the zinc is found with the base metals such as copper and lead and it has less affinity with oxides and strong affinity with sulphides. Sphalerite, a zinc sulphide ore, is majorly containing 60-62% of zinc. The other sources of zinc from the minerals are smithsonite, hemimorphite, quartzite, and hydro zincate.
The major sources of zinc contamination arise from several industrial activities such as mining, coal, waste combustion and steel and iron processing. Drinking water also contains certain amounts of Zn, which may be higher when it is stored in metal tanks. The acute toxicity arises from the ingestion of excessive amounts of zinc salts, either accidentally or as dietary supplement. Vomiting, nausea and stomach cramps usually occur after the consumption of more than 500 mg of zinc sulfate. In addition to that, the higher amounts of zinc affect gastrointestinal tract, liver, bone and prostate glands. Finally, Zn can interrupt the activity in soils, as it negatively influences the activity of microorganisms and earthworms, thus retarding the breakdown of organic matter. To combat this problem, techniques such as chemical precipitation, ion exchange, reverse osmosis, etc. are adopted, but these processes result in a huge amount of secondary sludge formation, inefficient removal of metals and are not cost effective. In recent times, an innovative, eco-friendly, cost-effective method has been introduced to treat the toxic heavy metals namely bioremediation. ―Bioremediation‖ is a process of removal of organic or inorganic contaminants by using bacteria, fungi, algae and its metabolites
In this research work, the potential of four bacterial strains of the Pseudomonas sp. such as P.putida, P.alcaligenes, P.aeruginosa and P.fluorescens and the extracellular proteins secreted by these four species for the bio-sorption of zinc has been investigated through batch experiments. The mechanisms of interaction between the zinc ion and the bacterial biomass as well as with the extracellular proteins have been elucidated. Additionally, a carbon paste electrode has been modified by using Pseudomonas sp. and its metabolites to develop biosensors for zinc and the lower limit of detection of zinc in aqueous solution has been determined.
The major objectives of this research work are specified below:
• To study the potential of Pseudomonas sp. such as P.putida, P.alcaligenes, P.aeruginosa and P.fluorescens for the bio sorption of zinc, in batch systems.
• To determine the speciation of zinc with respect to pH in the growth medium and the maximum inhibitory effect of zinc on the growth of the four chosen Pseudomonas sp.
• To isolate and characterize the extracellular proteins from the four Pseudomonas sp. such as P.putida, P.alcaligenes, P.aeruginosa and P.fluorescens.
• To study the biosorption of zinc by extracellular proteins secreted by the Pseudomonas sp.
• To elucidate the mechanisms involved in the biosorption of zinc at the microbe- metal interface and protein-metal ion interface for all the four systems by different characterization studies such as zeta potential, FTIR analysis and EDAX analysis.
• To develop a biomass modified CPE using bacterial cells and extracellular protein to detect the concentration of zinc in aqueous solutions adopting voltammetric techniques.
The significant results obtained from this research work are summarized as follows:
The initial studies were concentrated on the bio sorption of zinc by using four Pseudomonas species such as P.putida, P.alcaligenes, P.aeruginosa and P.fluorescens. The various factors affecting the bio sorption of zinc by these species were investigated by varying the contact time (10-80 min), pH (2-5±0.2), biomass concentration of the four species in the range of 108- 1011 cells / mL, and the initial zinc concentration from 5 mg/L to 80 mg/L respectively, keeping other parameters such as temperature and agitation speed constant in all the experiments. From the results obtained, the maximum percentage of biosorption achieved by the P.putida, P.alcaligenes, P.aeruginosa and P.fluorescens was found to be 60%, 93%, 70% and 65% respectively for 25 mg/L at pH 5±0.2. The equilibrium time taken by the four species to achieve maximum biosorption was about 10 min and the biosorption kinetics adhered to pseudo-second order reaction and the rate constants were determined for different concentrations of zinc. The biosorption isotherm followed both the Langmuir and Freundlich isotherm models. The Gibbs free energy (ΔG) values determined from the Langmuir isotherm model for all the four systems were found to be -26, -32, -30 and -28 kJ /mole respectively. The Gibbs free energy values indicate that the biosorption of zinc ions onto the bacterial surface is a chemi-sorption process involving co-ordination, complexation or chelation. The characterization studies, namely zeta potential, FTIR analysis and SEM-EDX were also carried out on the bacterial cells before and after interaction with zinc. These studies also provide evidence in support of the complexation of zinc with the functional groups on the bacterial cell surface apart from electrostatic interaction.
In the second part of the investigation, the inhibitory effect of zinc on the growth of four Pseudomonas sp. was investigated by varying the concentration of zinc from 50 mg/L to 1000 mg/L and the stability of zinc was analysed with respect to pH (2-12) with different concentrations from 50 - 1700 mg/L. It was found that in the absence of zinc the time taken to reach the exponential phase and the specific growth were almost the same for all the four systems. However, in the presence of zinc ions, the growth of the four Pseudomonas sp. was suppressed beyond 50mg/L of zinc. A control study on the stability of zinc in Luria broth medium showed that zinc was highly stable up to 200 mg/L from pH 2-8. However, the stability of zinc in the growth medium decreased beyond that concentration
Additionally, studies on the biosorption of zinc were performed using extracellular proteins isolated from the four Pseudomonas sp. The amount of protein was estimated by the Bradford protein assay method at 594 nm. The biosorption experiments were carried out by varying the protein concentration from 50 to 1000µg/mL and the zinc concentration from 50-1000 mg/L and keeping other parameters fixed, namely such as pH at 5±0.2, reaction time of 20 min, temperature at 30±0.2 and the speed of rotation of 200 rpm. It was found that the maximum percentage of zinc biosorbed by the proteins isolated from P.putida was found to be 91% at 500µg/mL of protein concentration and from the other three species, it was found to be about 60% of biosorption at the same protein concentration. The biosorption isotherms of zinc for extracellular protein adhered to the Giles H1 type for all the four systems. The maximum amount of zinc biosorbed by the protein isolated from P.putida, P.alcaligenes, P.aeruginosa and P.fluorescens was found to be 35.6, 19,18.3 and 10 mg/µg respectively and the Gibbs free energy values were found to be -32, -22,-22 and -23 kJ/mole. The mechanisms involved in protein-zinc interaction were elucidated using FTIR analysis and EDX analysis. The FTIR analysis revealed, that the zinc ions were complexed with carboxylic and amine functional groups.
Further, the potential of P.putida, P.alcaligenes, P.aeruginosa and P.fluorescens and their extracellular proteins of P.putida as biosensors for detecting zinc ions in aqueous solutions, using electrochemical methods such as, Cyclic Voltammetry and Differential pulse anodic stripping voltammetry, was assessed. The developed carbon paste electrode coated by the biomass showed an approximately 3-fold increase in the sensing of Zn2+ ion in comparison with the bare electrode. The lower limit of detection of the biosensor for zinc ions by Cyclic voltammetry was found to be 10-6 M, and in case of DPASV the lower limit of detection was about 10-7M. The lower limit of detection of the protein modified biosensor for zinc ions by cyclic voltammetry was found to be 10-7M and in the case of DPASV method the lower limit of detection was found to be 10-9 M.
37
Ebinesar, J. S. S. Allwin. "Bioremediation of Zinc using Pseudomonas Species - Mechanistic Studies and Biosensor Applications." Thesis, 2016. http://hdl.handle.net/2005/3210.
Full textAbstract:
The rivers, lakes and seas are the major water sources for the animal and plant kingdom in this earth. In recent times, the usage and wastage of water have been increasing due to the uncontrolled population growth. In addition to that, the rapid industrialization over the years has led to the gradual depletion of the natural resources like water, soil and air. Some of these industries discharge contaminants like organic products and inorganic (or) toxic heavy metals without treatment into the environment, leading to its degradation. Zinc is the 24th most abundant element present in the earth crust, amounting 75 ppm (0.0075%). The concentration of zinc present in the soil and seawater is about 64 ppm and 30 ppb respectively (Emsley, 2001). Generally, the zinc is found with the base metals such as copper and lead and it has less affinity with oxides and strong affinity with sulphides. Sphalerite, a zinc sulphide ore, is majorly containing 60-62% of zinc. The other sources of zinc from the minerals are smithsonite, hemimorphite, quartzite, and hydro zincate.
The major sources of zinc contamination arise from several industrial activities such as mining, coal, waste combustion and steel and iron processing. Drinking water also contains certain amounts of Zn, which may be higher when it is stored in metal tanks. The acute toxicity arises from the ingestion of excessive amounts of zinc salts, either accidentally or as dietary supplement. Vomiting, nausea and stomach cramps usually occur after the consumption of more than 500 mg of zinc sulfate. In addition to that, the higher amounts of zinc affect gastrointestinal tract, liver, bone and prostate glands. Finally, Zn can interrupt the activity in soils, as it negatively influences the activity of microorganisms and earthworms, thus retarding the breakdown of organic matter. To combat this problem, techniques such as chemical precipitation, ion exchange, reverse osmosis, etc. are adopted, but these processes result in a huge amount of secondary sludge formation, inefficient removal of metals and are not cost effective. In recent times, an innovative, eco-friendly, cost-effective method has been introduced to treat the toxic heavy metals namely bioremediation. ―Bioremediation‖ is a process of removal of organic or inorganic contaminants by using bacteria, fungi, algae and its metabolites
In this research work, the potential of four bacterial strains of the Pseudomonas sp. such as P.putida, P.alcaligenes, P.aeruginosa and P.fluorescens and the extracellular proteins secreted by these four species for the bio-sorption of zinc has been investigated through batch experiments. The mechanisms of interaction between the zinc ion and the bacterial biomass as well as with the extracellular proteins have been elucidated. Additionally, a carbon paste electrode has been modified by using Pseudomonas sp. and its metabolites to develop biosensors for zinc and the lower limit of detection of zinc in aqueous solution has been determined.
The major objectives of this research work are specified below:
• To study the potential of Pseudomonas sp. such as P.putida, P.alcaligenes, P.aeruginosa and P.fluorescens for the bio sorption of zinc, in batch systems.
• To determine the speciation of zinc with respect to pH in the growth medium and the maximum inhibitory effect of zinc on the growth of the four chosen Pseudomonas sp.
• To isolate and characterize the extracellular proteins from the four Pseudomonas sp. such as P.putida, P.alcaligenes, P.aeruginosa and P.fluorescens.
• To study the biosorption of zinc by extracellular proteins secreted by the Pseudomonas sp.
• To elucidate the mechanisms involved in the biosorption of zinc at the microbe- metal interface and protein-metal ion interface for all the four systems by different characterization studies such as zeta potential, FTIR analysis and EDAX analysis.
• To develop a biomass modified CPE using bacterial cells and extracellular protein to detect the concentration of zinc in aqueous solutions adopting voltammetric techniques.
The significant results obtained from this research work are summarized as follows:
The initial studies were concentrated on the bio sorption of zinc by using four Pseudomonas species such as P.putida, P.alcaligenes, P.aeruginosa and P.fluorescens. The various factors affecting the bio sorption of zinc by these species were investigated by varying the contact time (10-80 min), pH (2-5±0.2), biomass concentration of the four species in the range of 108- 1011 cells / mL, and the initial zinc concentration from 5 mg/L to 80 mg/L respectively, keeping other parameters such as temperature and agitation speed constant in all the experiments. From the results obtained, the maximum percentage of biosorption achieved by the P.putida, P.alcaligenes, P.aeruginosa and P.fluorescens was found to be 60%, 93%, 70% and 65% respectively for 25 mg/L at pH 5±0.2. The equilibrium time taken by the four species to achieve maximum biosorption was about 10 min and the biosorption kinetics adhered to pseudo-second order reaction and the rate constants were determined for different concentrations of zinc. The biosorption isotherm followed both the Langmuir and Freundlich isotherm models. The Gibbs free energy (ΔG) values determined from the Langmuir isotherm model for all the four systems were found to be -26, -32, -30 and -28 kJ /mole respectively. The Gibbs free energy values indicate that the biosorption of zinc ions onto the bacterial surface is a chemi-sorption process involving co-ordination, complexation or chelation. The characterization studies, namely zeta potential, FTIR analysis and SEM-EDX were also carried out on the bacterial cells before and after interaction with zinc. These studies also provide evidence in support of the complexation of zinc with the functional groups on the bacterial cell surface apart from electrostatic interaction.
In the second part of the investigation, the inhibitory effect of zinc on the growth of four Pseudomonas sp. was investigated by varying the concentration of zinc from 50 mg/L to 1000 mg/L and the stability of zinc was analysed with respect to pH (2-12) with different concentrations from 50 - 1700 mg/L. It was found that in the absence of zinc the time taken to reach the exponential phase and the specific growth were almost the same for all the four systems. However, in the presence of zinc ions, the growth of the four Pseudomonas sp. was suppressed beyond 50mg/L of zinc. A control study on the stability of zinc in Luria broth medium showed that zinc was highly stable up to 200 mg/L from pH 2-8. However, the stability of zinc in the growth medium decreased beyond that concentration
Additionally, studies on the biosorption of zinc were performed using extracellular proteins isolated from the four Pseudomonas sp. The amount of protein was estimated by the Bradford protein assay method at 594 nm. The biosorption experiments were carried out by varying the protein concentration from 50 to 1000µg/mL and the zinc concentration from 50-1000 mg/L and keeping other parameters fixed, namely such as pH at 5±0.2, reaction time of 20 min, temperature at 30±0.2 and the speed of rotation of 200 rpm. It was found that the maximum percentage of zinc biosorbed by the proteins isolated from P.putida was found to be 91% at 500µg/mL of protein concentration and from the other three species, it was found to be about 60% of biosorption at the same protein concentration. The biosorption isotherms of zinc for extracellular protein adhered to the Giles H1 type for all the four systems. The maximum amount of zinc biosorbed by the protein isolated from P.putida, P.alcaligenes, P.aeruginosa and P.fluorescens was found to be 35.6, 19,18.3 and 10 mg/µg respectively and the Gibbs free energy values were found to be -32, -22,-22 and -23 kJ/mole. The mechanisms involved in protein-zinc interaction were elucidated using FTIR analysis and EDX analysis. The FTIR analysis revealed, that the zinc ions were complexed with carboxylic and amine functional groups.
Further, the potential of P.putida, P.alcaligenes, P.aeruginosa and P.fluorescens and their extracellular proteins of P.putida as biosensors for detecting zinc ions in aqueous solutions, using electrochemical methods such as, Cyclic Voltammetry and Differential pulse anodic stripping voltammetry, was assessed. The developed carbon paste electrode coated by the biomass showed an approximately 3-fold increase in the sensing of Zn2+ ion in comparison with the bare electrode. The lower limit of detection of the biosensor for zinc ions by Cyclic voltammetry was found to be 10-6 M, and in case of DPASV the lower limit of detection was about 10-7M. The lower limit of detection of the protein modified biosensor for zinc ions by cyclic voltammetry was found to be 10-7M and in the case of DPASV method the lower limit of detection was found to be 10-9 M.
38
Berry, Chrystal. "An investigation of the mechanisms underlying biological control activity of a novel canola-associated bacterial isolate, Pseudomonas species DF41." 2010. http://hdl.handle.net/1993/4181.
Full textAbstract:
Abstract
The ability of several plant-associated bacteria to inhibit the proliferation of root-pathogens has been well established whereas considerably less has been reported about bacterial species inhibiting pathogens on the phylloplane. Sclerotinia sclerotiorum is the fungal causative agent of stem rot and is capable of infecting over 400 plant species, including flowering canola plants. For this reason, there is a need for disease management strategies targeted at preventing sclerotinia infection.
Pseudomonas species DF41 was isolated from the canola rhizosphere and found to be an excellent antagonist of sclerotinia stem rot. Therefore, research efforts turned towards elucidating the mechanisms underlying DF41 antifungal (AF) activity. A random transposon mutagenesis approach facilitated the identification of genes essential for DF41 fungal antagonism. One gene that was identified, gacS, encodes the sensor kinase of the Gac two-component signal transduction system. Characterization of the DF41 gacS mutant revealed that this regulator is essential for secondary metabolite production. In other bacteria, the Gac system activates target gene expression by upregulating the transcription of small, untranslated RNA molecules (sRNA). A sRNA molecule called RsmZ was found to act as a downstream regulatory element in the DF41 Gac regulatory cascade.
Furthermore, we discovered that DF41 is producing acyl homoserine lactone (AHL) signalling molecules. This prompted us to investigate the effect of quorum sensing (QS) on phenotypes contributing to AF activity. In DF41, AHL- signalling is not important for secondary metabolite production but does influence motility and may indirectly govern gene expression by controlling other regulatory elements
Screening of our transposon library led to the identification of a non-ribosomal peptide synthetase gene involved in synthesis of a cyclic lipopeptide (CLP) molecule. High-performance liquid chromatography (HPLC) and mass spectrometry (MS) enabled the identification of an unusual CLP and we propose a preliminary structure containing some unique features. The role of this molecule in Pseudomonas sp. DF41 AF activity was also elucidated.
Altogether, this investigation has revealed a number of important findings regarding how DF41 functions as a biocontrol agent. This information will allow us to use DF41 more effectively in the future in managing sclerotinia stem rot on canola plants.
39
Wood, Piper Louise. "Chemotaxis to naphthalene by Ralstonia species strain U2 and Pseudomonas putida G7." Diss., 2009. http://proquest.umi.com/pqdweb?did=1987414121&sid=1&Fmt=2&clientId=48051&RQT=309&VName=PQD.
Full text
40
Fernandes, Nathalie Madalena Melro. "Characterisation of the activity of biosurfactants produced by pseudomonas species isolated from foods." Thesis, 2010. http://hdl.handle.net/10539/7667.
Full textAbstract:
Spoiled food products were screened for biosurfactant-producing Pseudomonas strains, which
were then evaluated for antimicrobial activity and the ability to grow on two model
hydrocarbons. Strains isolated from 14 different spoiled food products were screened for
biosurfactant production using the drop collapse assay, of which 5.6% tested positive. None
exhibited emulsifying activity. The strains were isolated predominantly from leafy vegetable
products, and bottled mineral water and low-fat milk; the latter two of which had the lowest APC
and PC, respectively. The sources of biosurfactant-producers suggest an attachment role for
biosurfactants, rather than one of directly increasing the availability of hydrophobic nutrients to
spoilage bacteria. Biosurfactant-producing strains were evaluated for antibacterial activity against
potentially pathogenic and food spoilage bacteria using the spot-on-lawn assay, of which 56%
exhibited activity against only Gram-positive bacteria, predominantly B. cereus ATCC 10702.
Strains found to be active against B. cereus ATCC 10702 were subjected to treatments with
protease, heat and organic solvents in order to determine their stability, and 6 of those isolates
were further characterised by TLC. The combined data suggested that the majority of compounds
produced by the strains isolated in this study produce cyclic lipopeptides, some of which may be
novel. Identification by 16S rRNA sequencing identified the antibacterial strains as Pseudomonas
(8), B. pumilis (9) and Proteus vulgaris (1). Phylogenetic analysis of the sequences also showed
that the strains are closely related to other bacteria with biosurfactant-producing, antimicrobial and biodegradative activities. The ability of 8 biosurfactant-producing strains (3 Pseudomonas, 1
Proteus, 4 B. pumilis) and 2 consortia (Gram-negative and -positive) to grow in minimal media
supplemented with n-hexadecane (MMH) or mineral motor oil (MMMO) was evaluated. All of
the strains and both consortia reached high cell numbers (>7 – 9 log CFU/ml); however, no
significant differences (P<0.05) were observed between individual strains inoculated into either
medium. The Gram-negative strains and consortium grew at lower rates in MMMO than in
MMH, and when compared with the Gram-positive strains and consortium. P. fulva 381C grew at
a significantly lower (P<0.05) rate when grown in MMMO. Furthermore, the consortia did not
achieve significantly higher (P<0.05) cell numbers or grow better than individually inoculated
strains in either medium. This study is the first to document antibacterial activity by P. fulva, and
hydrocarbon and n-alkane utilisation by strains of P. fulva and Proteus vulgaris, respectively.
41
Vimalnath, S. "Bioremediation of Lead from Aqueous Solutions using Pseudomonas Species - Mechanisms & Biosensor Applications." Thesis, 2015. http://etd.iisc.ac.in/handle/2005/4118.
Full textAbstract:
Industrialization, urbanization and technological developments have improved the standard of living for humans on the one hand, but they also have resulted in the generation of wastes containing toxic heavy metals that are detrimental to the ecosystem on the other hand. Therefore, the treatment of waste water containing toxic heavy metals before discharging into the environment has become imperative. Though, the conventional waste water treatment methods like adsorption, electrochemical process, ion-exchange, precipitation, solvent extraction, etc. have served the purpose of removing toxic heavy metals, they have certain limitations such as formation of secondary sludge, inefficiency in removing lower metal concentration, high cost, to name a few. Thus, it becomes of interest to explore alternative cost effective methods capable of removing lower concentrations of heavy metals from waste water.
The method of bioremediation which uses microorganisms for toxic heavy metal removal has gained significance. Various combinations of microorganisms and heavy metals have been researched to assess the abilities of the selected microorganisms in removing the considered metals. Majority of the research studies have focused on the biosorption of metals by the whole cells. However, there is a paucity of research on the role played by the individual cell wall components in metal removal. In addition to remediation, the detection of heavy metals in waste waters is also of equal importance.
In the present research study, the significance of bacteria of Pseudomonas species namely P. putida, P. aeruginosa and P. fluorescens for lead remediation have been assessed. Further, detailed studies have been carried out to elucidate the mechanisms of lead removal through the assessment of the roles played by the individual cell wall components. The lead removal capacities of the individual EPS components purified from the Pseudomonas sp. have been determined. Various strategies have been adopted to enhance the lead removal capacities of the three Pseudomonas sp. by thermolysis. For the biosorption studies, the parameters namely pH, time of contact, biomass loading and lead concentration have been optimized to obtain the maximum lead binding. Apart from lead removal, biologically modified carbon paste electrodes (CPEs) have been developed using the Pseudomonas sp. cells and their EPS components.
The major objectives of this research work are enumerated as follows:
1. Study of the bioremediation of lead from aqueous solutions using cells of P. putida, P. aeruginosa and P. fluorescens.
2. Understanding the role of bacterial cell wall and its components in lead uptake.
3. Effect of thermolysis of the chosen bacterial cells on lead uptake
4. Determination of the lead uptake capacity of extracellular polymeric substances (EPS) of the selected Pseudomonas sp. namely, proteins, polysaccharides, biosurfactants and DNA.
5. Enrichment of lead binding proteins from total bacterial protein and examination of the lead binding capacity of the purified protein.
6. Comparison of the protein profiles of the three Pseudomonas sp. in the absence and presence of lead.
7. Detection of Pb (II) ions in aqueous solutions using carbon paste electrodes modified with Pseudomonas sp. cells and their EPS components using an electro-analytical technique.
The key findings of the research work are summarized below:
The fully grown cells of Pseudomonas sp. harvested from the nutrient medium have been used for the experiments. The lead biosorption studies using the Pseudomonas sp. show substantial lead biosorption by all the three bacteria chosen namely, P. putida, P. aeruginosa and P. fluorescens in independent studies. The three Pseudomonas sp. however show a variation in their lead removal capacities. The highest lead removal is obtained when P. putida is used as the biosorbent. The characterization studies using FTIR, EDAX and zeta potential have been carried out for the Pseudomonas sp. cells before and after interaction with lead. The EDAX studies confirm the presence of lead ions on the Pseudomonas sp. surface. Electro-kinetic studies indicate that the negatively charged bacterial surface, become less electronegative after interaction with lead. The carboxyl and phosphate groups are found to play major role in lead binding by P. putida and P. fluorescens. In addition to the carboxyl and phosphate groups, amide group also play role in lead binding on the P. aeruginosa cell. The lead biosorption using all the three Pseudomonas sp. adhere to the Langmuirian isotherm model and follow the pseudo second order kinetics. The lead removal by the Pseudomonas sp. is further improved after thermolysis presumably due to the exposure of more lead binding sites. After thermolysis, the lead uptake is found to increase by about 27 % in the case of P. putida, about 18 % in the case of P. aeruginosa and about 26 % in the case of P. fluorescens.
Taking into consideration that the intact and thermolysed Pseudomonas sp. are effective in removing lead, further studies have been carried out to understand which of the individual cell wall components namely DNA, protein, polysaccharide or lipid play a role in lead uptake. The biosorption studies carried out after digesting the cell wall components one at a time using specific enzymes have shown that the lead uptake differs for each component, both in the case of the intact and the thermolysed cells. Though all of the major cell wall components are found to be responsible for lead removal, a greater reduction in lead removal is observed, when the polysaccharide component of Pseudomonas sp. is digested and used as a biosorbent.
When the individual cell wall components namely DNA, protein, polysaccharide and biosurfactant are studied for their lead binding capacities in their purified forms, the purified protein from all the three Pseudomonas sp. are found to remove a higher percentage of lead, compared to the other purified components. In the case of DNA, the lead biosorption has been studied using both ssDNA and dsDNA. Amongst the two forms of DNA, ssDNA shows a better lead uptake vis-a-vis dsDNA. This is possibly due to the exposure of more lead binding sites in the case of ssDNA which are otherwise masked in the double helical structure of dsDNA. Further, the hydrophilic part of the DNA is found to play a major role in lead binding compared to the hydrophobic part.
Recognizing that the purified total protein is found to be capable of removing more lead compared to the other components, an affinity column chromatography technique has been used to enrich the lead binding protein from the total proteins. The SDS-PAGE documentation of the total and enriched proteins has confirmed the enrichment of specific proteins. The enriched protein fractions exhibit 65 to 95 % of the lead binding capacities of their corresponding total proteins in all the three species of Pseudomonas studied. The SDS-PAGE analysis of protein profile in the absence and presence of lead have shown significant differences consequent to lead binding.
Extensive lead detection studies carried out using carbon paste electrode (CPE) modified with the Pseudomonas sp. cells and their purified EPS components have highlighted the potential of the biomass modified CPEs for lead detection. The lowest limit of detection (LLOD) for lead has been estimated for each of the modified CPEs studied. The estimated LLODs show that amongst the many biomass modified CPEs studied, the CPE modified using whole cells indicate a better detection of lead compared to the individual purified EPS components. Amongst the CPEs modified using whole cells, the one modified by blending the lyophilized cells with carbon paste is capable of detecting lower concentrations of lead than the one modified with drop coated cells.
42
Yap, Scott. "The efficacy of sewage influent-isolated bacteriophages on Pseudomonas aeruginosa in a mixed-species biofilm." Thesis, 2016. http://hdl.handle.net/10754/621991.
Full textAbstract:
The growth of environmentally persistent biofilms in cooling towers causes several associated problems, including microbiologically-induced corrosion (MIC) and biofouling. Current chemical control methods are not only ineffective against biofilms and costly to procure, they also have downstream environmental impacts when released untreated, or incur additional treatment costs. Bacteriophages are alternative biofilm control agents that have the potential to be more effective, cheaper to produce and yet have a more benign effect on the environment. In this study, biofilms grown under conditions simulating seawater fed cooling towers were characterized and the differences in growth and community make-up across time and different substrates were assessed. An MIC associated bacterium common in cooling tower water, P. aeruginosa, was chosen. Seven bacteriophage strains found to be effective against the chosen bacterium were isolated from wastewater influent. The relative effectiveness of these strains was measured against P. aeruginosa across different salinities. Separate biofilms fed with P. aeruginosa enriched seawater were characterized and the effectiveness of the isolated strains, singly and in cocktails, against the enriched biofilms was measured.
43
Ku, Tzu Hsuan, and 顧子瑄. "Inhibition Mechanisms of Acetylcholinesterase, Butyrylcholinseterase, Pseudomonas Species Lipase, and Cholesterol Esterase by 3-Acyloxy-Methylsulfonylbenzene." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/41727766095076570408.
Full text
44
Alghanmi, Linah Y. "Developing Production Methods for Different Microbial Strains and Beneficial Testing on Crop Species." Thesis, 2021. http://hdl.handle.net/10754/670177.
Full textAbstract:
Microorganisms will play a significant role in the agricultural revolution in the coming decades and help meet the growing population's needs. Hence, understanding the impact of beneficial bacteria on crop development is key to the future of developing microbial products. The ability of PGPB to increase crop yields has been recently investigated in agriculture, as PGPB can support and protect plants under different stresses. Since PGPB interactions occur naturally, finding a method to apply beneficial bacteria while maintaining their efficiency and quality is a topic of interest. PGPB have been used as microbial inoculants, biofertilizers, and also as seed coatings. Preservation of microorganisms through desiccation has been used as the preferred method for long-term storage of microbial culture. The use of dry powders is favored over liquid cultures due to their ease of transportation and better quality control. For microbial preservation, freeze-drying has been defined as the most convenient and satisfactory preservation method for long-term storage. Freeze-drying is generally preferred over other drying techniques as it gives a high-quality dehydrated product. However, to reach a high-quality product, many parameters need to be monitored, such as bacterial cell concentration, growth medium, lyophilization buffer, rehydration, and duration of freeze-drying.
In this research, SA190 was freeze-dried with 10% sucrose mixed with 5% trehalose as lyophilization buffer. Pseudomonas argentinensis SA190 was isolated from the root nodules of the desert plant Indigofera argentae in Saudi Arabia, specifically Jizan. The SA190 freeze-dried product was examined by several tests to assess the product viability and quality, such as accelerated test and water stability test.
For future work, the effect of freeze-dried SA190 on plant growth and crop yield will be investigated. Moreover, optimization of the freeze-drying process, formulation, and packaging for commercial will be considered. In addition, bacterial strains isolated in DARWIN21 project with promising effects on plant growth, will be subjected to freeze-drying process.
45
Jen, Lin Jun, and 林軍任. "Inhibition mechanisms of acetylcholinesterase, butyrylcholinesterase, cholesterol esterase, and pseudomonas species lipase by nitroglycerol and benzene-1,3,5-triol carbamates." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/82879114126305262465.
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BIN, JHANG TIAN, and 張田彬. "Mechanism of Inhibitions of Pseudomonas Species Lipase, Cholesterol Esterase, Acetylcholinesterase, and Butrylcholinesterase by 1-Acyloxy-10-Hexylcarbamyl-Decanes." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/00486905004652221313.
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Traub, Petra Christine [Verfasser]. "Gensynthese, Expression und Refolding der Lipasen aus Pseudomonas species KWI 56 und Chromobacterium viscosum / vorgelegt von Petra Christine Traub." 2000. http://d-nb.info/958924074/34.
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48
Arévalo-Ferro, Catalina [Verfasser]. "A proteomics view of quorum-sensing regulated and surface induced genes in representative Pseudomonas and Burkholderia species / Catalina Arévalo-Ferro." 2004. http://d-nb.info/97204650X/34.
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49
Duke, Kelly. "Global changes in Brassica napus gene activity in response to Sclerotinia sclerotiorum and the biocontrol agent Pseudomonas chlororaphis PA23." 2016. http://hdl.handle.net/1993/31771.
Full textAbstract:
The biological control agent Pseudomonas chlororaphis PA23 is effective at protecting Brassica napus (canola) from the necrotrophic fungus Sclerotinia sclerotiorum via direct antagonism. Despite the growing importance of biocontrol bacteria in protecting crop plants from fungal pathogens, little is known about how the host plant responds to bacterial priming on the leaf surface and certainly nothing about global changes in gene activity in the presence and absence of S. sclerotiorum. PA23 priming of mature canola plants reduced the number of lesion-forming petals by 90%. Global RNA sequencing of canola tissue at the host-pathogen interface showed a 16-fold reduction in the number of genes uniquely upregulated in response to S. sclerotiorum when pretreated with PA23. Upstream defense-related gene patterns suggest MAMP-triggered immunity via surface receptors detecting PA23 flagellin and peptidoglycans. Although systemic acquired resistance (SAR) was induced in all treatment groups, a response centered around a glycerol-3-phosphate (G3P)-mediated pathway was exclusively observed in canola plants treated with PA23 alone. Activation of these defense mechanisms by PA23 involved production of reactive oxygen species as well as pronounced thylakoid membrane structures and plastoglobule formation in leaf chloroplasts. PA23 therefore primes defense responses in the plant through the induction of unique local and systemic regulatory networks.October 2016
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Yeh, Shih-Chieh, and 葉世傑. "The Inhibition Mechanisms of Acetylcholinesterase, Butyrylcholinesterase, Cholesterol Esterase and Pseudomonas Species Lipase by Optically Pure exo-Norbornyl-N-n-butylcarbamates and the Decarbamylation Constants for the Inhibition of Butyrylcholinesterase." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/79094491096717421867.
Full textAbstract:
碩士國立中興大學
生物化學研究所
88
Abstract The thesis is divided into three parts. The first part is the preparation of optically pure R- and S-exo-Norborneols. Porcine pancreatic lipase catalyzes stereospecifically the hydrolysis of S-exo-Norbornyl butyrate from its racemates to produce S-exo-Norborneol, and the recovery of R-exo-Norbornyl butyrate. R-exo-Norborneol is prepared from the basic hydrolysis of R-exo-Norbornyl butyrate. The second part is the synthesis of optically pure R- and S-exo-Norbornyl-N-n-butylcarbamates as inhibitors of acetylcholinesterase, butylrylcholinesterase, cholesterol esterase and Pseudomonas species lipase and uses both carbamates to study the inhibition mechanism and stereospecificity of these enzymes. R-exo-Norbornyl-N-n-butylcarbamate is more potent inhibitor to these enzymes than the S enantiomer. The stop time assay of these enzymes with the R-exo-Norbornyl-N-n-butylcarbamate reveals that R-exo-Norbornyl-N-n-butylcarbamate is bound to the active site of butylrylcholinesterase but is not bound to the active sites of acetylcholinesterase, cholesterol esterase and Pseudomonas species lipase. Moreover the inhibitors bind to the peripheral anionic site of acetylcholinesterase or to the second alkyl chain binding site of cholesterol esterase and Pseudomonas species lipase. Third, p-nitrophenyl-N-alkylcarbamates are used to investigate the decarbamylation rate constants and the Taft free energy relationships for butylrylcholinesterase. The decarbamylation constant values are 10-fold less than those of carbamylation constant(kc). The result reveals that there are little relationship between the logarithms of the decarbamylation constant(kd) and the Taft-substituent(s*) and steric(Es) constants.