Search results for "Bactérie"
showing 10 items of 69 documents
Development of methods for the detection and quantification of spoilage microorganisms in wine : study of growing factors
2016
New practices used to elaborate wine lead to an increase of wine spoilage due to microorganisms. That is why, new technics have to be developed to quantify these microorganisms accurately, quickly and with low costs. The main wine spoilages are due to acetic acid bacteria (AAB) (A. aceti, A. pasteurianus, G. oxydans and Ga. liquefaciens) and Brettanomyces bruxellensis development. AAB transforms ethanol to acetic acid while B. bruxellensis transforms hydroxycinnamic acids to ethyl phenols (EP) (unpleasant odor molecules). In order to detect these wine spoilage microrganisms, flow cytometry coupled to fluorescent in situ hybridization has been assessed. No reproducible results have been deve…
UV resistance of Bacillus subtilis spores - Involvement of DPA and characterization by photonic microscopy
2022
The aim of this project was to study the UVc resistance of Bacillus subtilis spores. The first part of this project focused on the dipicolinic acid molecule (DPA) which is known to be involved in the UV resistance of spores. However, some points remain unresolved. In particular, it is known that this molecule forms fluorescent photoproducts (DPAp), which were not identified at the beginning of this project. No information concerning the role of these DPAp in UVC resistance was available at that time. During this project, a protocol was established to follow the appearance of these photoproducts directly inside the spore core. A method was also set up to artificially introduce DPAp into the …
Regulation of stress response in Oenococcus oeni as a function of environmental changes and growth phase
2000
International audience; Oenococcus oeni is a lactic acid bacterium which is able to grow in wine and perform malolactic fermentation. To survive and grow in such a harsh environment as wine, O. oeni uses several mechanisms of resistance including stress protein synthesis. The molecular characterisation of three stress genes hsp18, clpX, trxA encoding for a small heat shock protein, an ATPase regulation component of ClpP protease and a thioredoxin, respectively, allow us to suggest the existence in O. oeni of multiple regulation mechanisms as is the case in Bacillus subtilis. One common feature of these genes is that they are expressed under the control of housekeeping promoters. The express…
A metabolomic study of yeast/bacteria interactions
2015
As a complex microbial ecosystem, wine is a particularly interesting model for studying interactions between microorganisms. Contact-independent interactions (indirect interactions) between the yeast Saccharomyces cerevisae and the lactic acid bacterium Oenococcus oeni have a direct effect on malolactic fermentation (MLF), induction and completion, which is an important factor in wine quality. Yeast strains could be classified as MLF+ phenotype if it usually stimulates the bacterial growth or MLF- in the opposite case. The known metabolites that stimulate or inhibit the MLF cannot always explain the phenotypic distinction. In this work, a multidisciplinary workflow combining non-targeted me…
Influence of biotic and abiotic factors on soil organic matter dynamics assessed by the biogeochemical characterisation of soluble organic matter
2014
Soils are the greatest reservoir of C on the continents, and organic matter mineralisation bymicrobial activity represents the major part of the CO2 emitted by terrestrial ecosystems.In this work, we studied water-extractable organic matter (WEOM), which corresponds to themore reactive fraction of soil organic matter (SOM). Our objectives were (i) to identify therelationships of WEOM dynamics with bacterial communities, and with soil physico-chemicalparameters; (ii) to provide a precise chemical characterisation of WEOM.There is a strong link between SOM solubility and the structure of bacterial communities, andan erosion of their diversity has an impact on SOM and WEOM dynamics, and leads …
Influence of organic matters on the bacterial AsIII oxidation in polluted soils
2014
International audience; The global bacterial AsIII-oxidizing activity tends to decrease As toxicity in soils and its transfer toward underlying aquifers. The influence of different types of organic matters on arsenic speciation by pure strains and soils microflora was determined. Experimental results show that the presence of organic matter has a negative effect on the specific rate of AsIII oxidation by pure strains presenting different metabolisms. In parallel, experiments are performed with various soils from different types of polluted sites: former mining and industrial sites, forest and agricultural soils impacted by mining activities. The effect of yeast extract on the AsIII-oxidizin…
Nodulating symbiotic bacteria and soil quality
2005
Chapitre 9 : Plant microbe interactions and soil quality Partie : 9-2; International audience
Conférence invitée : " Mécanismes et gestion de la symbiose mycorhizienne dans les agro-écosystèmes"
2017
National audience; Présentations et échanges sur les résultats de l’INRA à propos desmycorhizes : quelles stratégies développées par les plantes pour mieuxutiliser les ressources naturelles du sol ? Comment favoriser desconditions favorables à l'installation et à la vie des champignonsbénéfiques du sol ? Quelle influence la nature du sol a-t’elle sur laquantité et la diversité de champignons mycorhiziens ? Quid desintrants ? Les fongicides ont-ils vraiment un effet délétère sur leschampignons Mycorhiziens ? La résistance des plantes aux pesticidespeut-elle être favorisée par les mycorhizes ?
Non, les sols viticoles ne sont pas morts
2019
National audience
Infestation chez le pigeon biset (Columbia livia) en environnement urbain par différentes souches bactériennes pathogènes : prévalence dans la popula…
2014
Rapport de Stage de Master 2 EA MERS CT3; Master; La dissémination des zoonoses est une préoccupation majeure pour les autorités concernées en termes de santé publique. Ces maladies font l’objet de suivi temporel et spatial afin de comprendre les facteurs favorisant leur dissémination. Les oiseaux, de par leur forte capacité de mouvement représentent un groupe taxonomique très étudié dans la dissémination des pathogènes. Le pigeon biset (Columbia liva) est une des espèces les plus présentes dans l’environnement urbain et peut-être porteur de différentes souches bactériennes pathogènes. Cette étude s’est intéressé à estimer l’état sanitaire des pigeons au sein de la ville de Dijon. La recher…