Дисертації з теми "Microorganisme extracellulaire"
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Guilhot, Robin. "Écologie des drosophiles et de leurs symbiotes microbiens en conditions naturelles." Electronic Thesis or Diss., Montpellier, SupAgro, 2020. http://www.theses.fr/2020NSAM0007.
Microbiota and symbiotic interactions are priority topics that are often explored using the Drosophila model organism. However, existing knowledge of natural relationships, i.e. in situ, between Drosophila flies and microbial symbionts is fragmented. Understanding coevolution between a host and its microbial symbionts requires a detailed understanding of the co-effects between symbiotic partners. In this PhD, I empirically studied the interactions between Drosophila flies (the model organism D. melanogaster and the pest species D. suzukii) and extracellular microbial symbionts (bacteria and yeasts) using wild strains under near-natural conditions. I investigated three main questions: (i) how do Drosophila flies acquire and transmit their microbial symbionts along their life cycle; (ii) how do these microorganisms affect host development; (iii) how do these microorganisms interact? My work revealed that yeasts and bacteria are not simply sources of nutrition (i.e. resource acquisition) for Drosophila but also influence how fly larva allocate resources between different life history traits (i.e. developmental plasticity). Second, the conducted study on microbial acquisition and transmission phenomena under near-natural conditions showed that symbionts are partially acquired from the environment, conserved through different life stages, and transmitted between generations and through mating. Thirdly, I found substantial interactions between microbial symbionts that affect their multiplication and transmission between host generations. These results reveal natural interactions of some complexity between Drosophila flies and their microbial symbionts. This demonstrates not only that these interactions are durable but also composed of nested effects that are simultaneous and invisible in obligatorily simplified laboratory systems. In addition, this work brings new elements likely to improve population control of the pest D. suzukii
Buchon, Laurent. "Influence de la température sur la physiologie de la croissance et la production d'enzymes exocellulaires chez des bactéries adaptées aux basses températures." Rouen, 2000. http://www.theses.fr/2000ROUES046.
Ngom, Marie Odile. "Induction and production of specific extracellular lipases from selected microorganisms." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0031/MQ64416.pdf.
Dusny, Christian [Verfasser]. "Microfluidics enable quantitative physiology of individual microorganisms in controlled extracellular environments / Christian Dusny." Aachen : Shaker, 2015. http://d-nb.info/1080763341/34.
Kolba, Clifford Andrew. "Intracellular and extracellular acid phosphatase activity in axenically cultured phosphate-deprived achlorophyllous euglena gracilis /." Access Digital Full Text version, 1994. http://pocketknowledge.tc.columbia.edu/home.php/bybib/11714372.
Typescript; issued also on microfilm. Sponsor: O. Roger Anderson. Dissertation Committee: Patricia L. Dudley. Includes tables. Includes bibliographical references (leaves 119-129).
Reid, Vernita Jennilee. "Extracellular acid proteases of wine microorganisms : gene identification, activity characterization and impact on wine." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/20322.
ENGLISH ABSTRACT: Non-Saccharomyces yeasts of oenological origin have previously been associated with spoilage or regarded as undesired yeasts in wine. However, these yeasts have recently come under investigation for their positive contribution towards wine aroma especially when used in sequential or co-inoculated fermentations with Saccharomyces cerevisiae. These yeasts are also known to secrete a number of enzymes that could be applicable in wine biotechnology. Amongst these enzymes are aspartic proteases. The secreted proteases from some non-Saccharomyces yeast may play a role in protein haze reduction, as demonstrated by some authors, while simultaneously increasing the assimilable nitrogen content of the wine for the utilization and growth of fermentative microorganisms. Moreover, the proteases may have an indirect effect on wine aroma by liberating amino acids that serve as aroma precursors. Although many screenings have been performed detecting protease activity in non-Saccharomyces yeasts, no attempts have been made to characterize these enzymes. This study set out to isolate and characterize genes encoding extracellular aspartic proteases from non-Saccharomyces yeasts. An enzymatic activity screening of a collection of 308 Saccharomyces and non-Saccharomyces yeasts, isolated from grape must, was performed. The aspartic protease-encoding genes of two non- Saccharomyces yeasts, which showed strong extracellular proteolytic activity on plate assays, were isolated and characterized by in silico analysis. The genes were isolated by employing degenerate and inverse PCR. One gene was isolated from Metschnikowia pulcherrima IWBT Y1123 and named MpAPr1. The other putative gene was isolated from Candida apicola IWBT Y1384 and named CaAPr1. The MpAPr1 gene is 1137 bp long, encoding a 378 amino acid putative protein with a predicted molecular weight of 40.1 kDa. The CaAPr1 putative gene is 1101 bp long and encodes a 367 amino acid putative protein with a predicted molecular weight of 39 kDa. These features are typical of extracellular aspartic proteases. The deduced protein sequences showed less than 40% homology to other yeast extracellular aspartic proteases. By heterologous expression of MpAPr1 in S. cerevisiae, it was confirmed that the gene encodes an extracellular acid protease. The expression of MpAPr1 was shown to be induced in media containing proteins as sole nitrogen source and repressed when a preferred nitrogen source was available. The gene was expressed in the presence of casein, bovine serum albumin (BSA) and grape juice proteins and repressed in the presence of ammonium sulphate. Expression was most induced in the presence of grape juice proteins, which was expected since these proteins are present in the natural habitat of the yeast. A genetic screening confirmed the presence of the MpAPr1 gene in 12 other M. pulcherrima strains isolated from grape juice. The extracellular protease activity of the strains was also visualized on plates. As far as we know, this is the first report on the genetic characterization of secreted aspartic proteases from non-Saccharomyces yeasts isolated from grape must and provides the groundwork for further investigations.
AFRIKAANSE OPSOMMING: Nie-Saccharomyces giste is voorheen met wynbederf geassosieer en hul teenwoordigheid in wyn is ongewens. Hierdie giste is onlangs ondersoek vir hulle positiewe bydrae tot wyn aroma, in veral sekwensiële en ko-inokulerings met Saccharomyces cerevisiae. Sommige van die nie-Saccahromyces giste skei ‘n verskeidenhied ensieme af wat moontlik vir die wynmaker van nut kan wees. Een groep van hierdie ensieme is die aspartiese suurproteases. Soos deur sommige navorsers aangetoon word, kan die proteases die vorming van proteïenwaasverlaging, terwyl dit terselfdertyd die assimilerende stikstofinhoud van die wyn vir die gebruik en groei van fermentasie-mikroörganismes verhoog. Die proteases kan moontlik ook ‘n indirekte uitwerking op die aromaprofiel van die wyn hê deur die vrystelling van aminosure wat as aromavoorlopers dien. Alhoewel baie studies gedoen is wat die ekstrasellulêre teenwoordigheid van proteases bevestig in nie-Saccharomyces giste wat van druiwesap/wyn afkoms is, is daar geen dokumentasie oor die genetiese karakterisering van hierdie ensieme beskikbaar nie. Die doel van hierdie studie was om gene wat aspartiese proteases in nie-Saccharomyces giste enkodeer, te isoleer en gedeeltelik te karakteriseer. ‘n Versameling van 308 Saccharomyces en nie-Saccharomyces giste wat uit druiwe sap geïsoleer is, is gesif vir ensiematiese aktiwiteit deur plaattoetse uit te voer. Twee gene wat aspartiese protease enkodeer, is geïsoleer van twee nie-Saccharomyces giste. Dit hetpositief gedurende die aktiwiteitstoetse getoets en is deur in silico–analise gekarakteriseer. Die gene is deur die uitvoering van gedegenereerde en inverse PKR geïdentifiseer. Een geen is vanaf Metschnikowia pulcherrima IWBT Y1123 geïsoleer en is MpAPr1 genoem, terwyl die ander van Candida apicola IWBT Y1384 geïsoleer en CaAPr1 genoem is. Die MpAPr1-geen is 1137 bp lank en enkodeer ‘n proteïen wat uit 378 aminosure bestaan met ‘n voorspelde molekulêre massa van 40.1 kDa. Daar teenoor is die CaAPr1-geen 1101 bp lank en enkodeer vir ‘n proteïen wat uit 367 aminosure met ‘n molekulêre massa van 39 kDa bestaan. Hierdie eienskappe is kenmerkend van aspartiese protease. Die afgeleide proteïenvolgorde het minder as 40% homologie met ander ekstrasellulêre aspartiese proteases vertoon, wat dui op die nuwigheid van hierdie ensieme. Die MpAPr1-geen is heterologies in S. cerevisiae YHUM272 uitgedruk en dit het bevestig dat die geen inderdaad ‘n ekstrasellulêre aspartiese protease enkodeer. Die MpAPr1-geen is uitgedruk in media wat alleenlik proteïen as stikstofbron bevat het, terwyl dit onderdruk is in gevalle waar ‘n verkose stikstofbron beskikbaar was. Die geen is uitgedruk in die teenwoordigheid van kaseïen, BSA en proteïene afkomstig vanaf druiwesap en in die teenwoordigheid van ammoniumsulfaat onderdruk. Die hoogste uitdrukking was in die teenwoordigheid van druifproteïene. Hierdie proteïene is teenwoordig in die natuurlike habitat van die gis en is dus dalk ‘n bekende stikstofbron vir die gis. ‘n Genetiese sifting het die teenwoordigheid van die MpAPr1-geen in 12 ander M. pulcherrima–rasse, wat ook van wynkundige oorsprong is, bevestig. Die aspartiese protease-aktiwiteit van die 12 rasse is ook op agarplate waargeneem. Na ons wete, is dit die eerste verslag oor die genetiese karakterisering van afgeskeide aspartiese proteases van nie- Saccharomyces giste van wynkundige oorsprong en verskaf die grondslag vir verdere ondersoek.
Kim, Hyun Jung. "The effect of extracellular and surface macromolecules on the deposition of pathogenic microorganisms in saturated porous media." Diss., UC access only, 2009. http://proquest.umi.com/pqdweb?did=1974753331&sid=1&Fmt=7&clientId=48051&RQT=309&VName=PQD.
Brauge, Thomas. "Étude des exopolysaccharides de la matrice extracellulaire des biofilms de Listeria monocytogenes." Thesis, Lille 1, 2015. http://www.theses.fr/2015LIL10151/document.
The aim of this work was to study the role of exopolysaccharides in the formation of Listeria monocytogenes biofilm and their resistance to cleaning procedure in industry. We showed that the major exopolysaccharide present in the extracellular matrix of L. monocytogenes biofilm was teichoic acid, which was identical at the structure to the parietal teichoic acid. We identified that 50% of 93 strains of 1/2a serotype studied had a mutation in the lmo2550 gene that could lead to non-branching of the teichoic acid with the N-Acetylglucosamine residue (GlcNAc). We therefore examined mutants of EGD-e reference strain which had inactivated lmo2549 or lmo2550 or lmo2537 or tagO1tagO2 genes allowing highlighting the absence of the GlcNAc residue on teichoic acids. The mutation of these genes had changed the L. monocytogenes surface properties, decreased the adhesion to stainless steel and modified the architecture of 48h-biofilms. Furthermore, they were more susceptible to a circuit cleaning procedure with an important detachment, a change in the architecture of the biofilm and the presence of non-cultivable but viable cells and dead cells after passage of the caustic soda flow versus the wild-type EGD-e strain. The aim of this work was to better understand the role of the extracellular matrix in the formation of L. monocytogenes biofilm and then find the procedure to eradicate it in the industrial environment
Kara, Fadime. "Investigation Of Sodium And Potassium Ions In Relation To Bioflocculation Of Mixed Culture Microorganisms." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608488/index.pdf.
0.3. The activated sludge reactors were operated until the reactors reached steady state and then related analyses were conducted. It was found that addition of potassium and sodium ions at increasing concentrations resulted in increase in total polymer concentration. However, potassium ions promoted the synthesis of both polysaccharide and protein type polymers whereas sodium ions tended to stimulate production of protein type polymers and had an affinity to bind more protein within the floc structure. Sodium sludges had lower hydrophobicity and higher surface charges, so sodium ions led to deterioration in flocculation of sludges. Addition of both these ions decreased the dewaterability, sodium ions had more detrimental effect on dewaterability of sludges compared to potassium ions. The examination of data related to settleability showed that potassium ions led to no drastic deterioration in settling characteristics of the activated sludge but the addition of sodium ions deteriorated the settleability. In addition, it was seen that while the addition of potassium ions to the feed led to a decrease in viscosity, increase in sodium concentration correlated with an increase in viscosity. Finally, the comparison of chemical oxygen demand (COD) removal efficiency of these cations showed that sodium is more efficient in COD removal.
Wargnies, Marion. "Adaptations métaboliques de Trypanosoma brucei en réponse à des variations des conditions intra- et extracellulaires." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0200/document.
Trypanosoma brucei is a protozoan parasite responsible for human African trypanosomiasis. His complex life cycle alternates between mammalian hosts and the insect vector, the tsetsefly. During this cycle, the parasite encounters dissimilar environments and adapts to the sechanging conditions by regulating his metabolism. We have studied intermediate and energetic metabolism of the procyclic form living in the midgut of the insect vector. In this glucose-depleted environment, gluconeogenesis is crucial for growth and viability of the parasites. Indeed, it allows the synthesis of hexoses phosphates and in particular glucose 6-phosphate which feeds several essential biosynthetic pathways. Our work has confirmed the existence of a gluconeogenic flux fed by proline and glycerol. We have shown that glycerol is an efficiently metabolized carbon source and is preferentially used by the procyclic form rather than proline or even glucose. This situation never described before highlights glycerol repression on glucose metabolism. We have also showed that the enzyme fructose 1,6-biphosphatase (FBPase), specific of the gluconeogenesis, is not essential for the viability ofthe parasite in glucose-depleted conditions, suggesting that there is an alternative to this enzyme. However, FBPase plays an important role for virulence of T. brucei in the insect. Moreover, we have showed another adaptation strategy developed by T. brucei which is basedo n genomic rearrangements leading to the synthesis of chimeric genes
Gardel, Emily Jeanette. "Microbe-electrode interactions: The chemico-physical environment and electron transfer." Thesis, Harvard University, 2013. http://dissertations.umi.com/gsas.harvard:11185.
Engineering and Applied Sciences
Pous, Rodríguez Narcís. "Bioremediation of nitrate-polluted groundwater using bioelectrochemical systems." Doctoral thesis, Universitat de Girona, 2015. http://hdl.handle.net/10803/302539.
La presència de nitrats (NO3-) en aigües subterrànies és una preocupació global. L’alt cost energètic i ambiental de les tecnologies actuals requereixen la investigació de noves estratègies. Aquesta tesi ha investigat la utilització de sistemes bioelectroquímics (BES) pel tractament d’aigües subterrànies contaminades per nitrats. Les BES es basen en microorganismes capaços de realitzar oxidacions/reduccions tot alliberant/captant electrons d’un elèctrode. Aquesta tesi ha investigat l’ús de bactèries capaçes d’utilitzar l’elèctrode com a donador d’electrons (biocàtode) per reduir el nitrat a dinitrogen gas (compost inert). Com a resultat, s’ha patentat un procés que permet desnitrificar a altes velocitats (700 gN•m-3NCC•d-1), a un cost energètic competitiu (0.68•10-2 – 1.27•10-2 kWh•gN-1tractat), sense generar fangs ni addicionar substàncies químiques. També s’ha caracteritzat electroquímicament els microorganismes i s’ha elucidat les subcomunitats microbianes responsables de la desnitrificació. En definitiva, aquesta tesi demostra que els sistemes bioelectroquímics poden esdevenir una alternativa competitiva pel tractament d’aigües subterrànies contaminades per nitrats
Pierre, Guillaume. "Caractérisation biochimique d’exopolymères d’origine algale du bassin de Marennes-Oléron et étude des propriétés physico-chimiques de surface de micro-organismes impliquées dans leur adhésion." Thesis, La Rochelle, 2010. http://www.theses.fr/2010LAROS314/document.
The main goal of this thesis was to better understand the importance of Extracellular Polymeric Substances (EPS) in the structuring and formation of benthic biofilms; while considering a global conception of the ecological mechanisms involved in the functioning of intertidal mudflats. The development of the biochemical assays was done on the mucilage of the macroalgae Chaetomorpha aerea and allowed purifying a polysaccharide rich in galactose, showing a selective bactericidal activity against Staphylococcus aureus (ATCC 25923). Then, the biochemical and ecological studies concerning the EPS extracted from the local mudflat allowed studying their dynamic of production and composition in relation to environmental conditions. The presence of deoxy sugars and uronic acids in the bound EPS highlighted their important roles during the formation and the life of microphytobenthic biofilms. The last part of the work was used to characterize the acid/base of Lewis and hydrophilic/hydrophobic surface properties of the microalgae Navicula jeffreyi, involved in the formation of benthic biofilms, by using classical analysis methods. The use of a new method, named Inverse Gas Chromatography (IGC), allowed getting interesting and relatively similar results, confirming the potential of the method to study the surface properties of microorganisms
Haake, Zachary J. "Biogeochemical Gradients within an Acid Mine Drainage-Derived Iron Mound, North Lima, Ohio." University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1397816537.
Moon, Jonathan Lloyd. "Extracellular proteinases of pathogenic microorganisms." 2005. http://purl.galileo.usg.edu/uga%5Fetd/moon%5Fjonathan%5Fl%5F200512%5Fphd.
Laio, Zi-Yi, and 廖孜翊. "Biosorption of precious metal by microorganisms and their extracellular polysaccharides." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/e2y3vy.
元智大學
生物科技與工程研究所
107
Precious metals such as gold (Au) and palladium (Pd) are widely used in industrial and biomedical applications. Recovery of these precious metals has become an area of particular interest. Biosorption of these rare metals is of the promising approach for recovery of these metals from industrial wastes. However, these metal ions have also been recognized to possess antimicrobial properties. Microorganisms able to tolerate high concentrations of these metals may facilitate the application of biosorption of these precious metals We evaluate several heavy metal resistant strains including Pseudomonas aeruginosa EJ01 previously isolated from our laboratory for their ability to tolerate Pd when grown in general complex medium such as Luria-Bertani (LB) medium. These strains could grow in LB medium containing Pd ranging from 180 to 270 ppm. In addition to these heavy metal resistant strains, we also isolated two palladium resistant microorganisms from soil contaminated with high concentrations of heavy metals. The two isolates were able to tolerate Pd up to 360 ppm. Analysis of 16S rRNA gene sequences led to the identification of these two isolates as Ochrobactrum sp. and Microbacterium sp. and were designed as Ochrobactrum sp. strain 71 and Microbacterium sp. strain 73, respectively. It was found that about 25% of the total palladium concentration could be adsorbed when the microorganisms grown in a palladium-containing medium by ion inductively coupled plasma atomic emission spectrometry (NIEA W311.53C). According to the literature, the adsorption capacity of microorganisms for noble metals is mostly derived from the function of extracellular polysaccharides. Therefore, we also examined the extracellular polysaccharides extracted from Ochrobactrum sp. and Microbacterium sp. for palladium adsorption. The polysaccharide showed a significant adsorption effect on palladium, about 10-15%. Finally, the extracellular polysaccharides of the two strains were subjected to saccharide composition.
Ibrahim, Mukthar. "Role of neutrophil matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of metalloproteases-1 (TIMP-1) in the killing of microorganisms." Thesis, 2003. http://hdl.handle.net/10413/10140.
Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2003.