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Persistance et dissémination du plasmide pB10, vecteur de gènes de résistance aux antibiotiques, dans des biomasses issues de stations d'épuration d'eaux usées urbaines

Abstract : The widespread use of antibiotics since the 50s, generates a significant release of these molecules in the environment (excretion via urine and feces) which can be found at concentrations ranging from 1-100 ng/L in wastewater. Due to the high microbial biomass and the abundance of nutrients, wastewater treatment plants (WWTP) represent a suitable habitat for horizontal gene transfer. Because they occupy a key position between human activities and the environment, WWTP may play a major role in limiting the dissemination of antibiotic resistance genes, therefore contributing to the preservation The parameters which influence these transfers in wastewater treatment plants are still poorly known, especially because of methodological limitations. Therefore the aim of our study was to identify environmental factors affecting the stability and transfer of a mobile genetic element model, the plasmid pB10 in bacterial communities (biomass from wastewater treatment plants and river sediments) maintained in microcosms. So far, the transfer of resistance genes have been studied mainly with methods based on the cultivation of microorganisms on selective media that we know now they underestimate the observed phenomena. Also, an approach based on quantitative PCR was developed for detecting the release of a mobile DNA template from the host bacterium E. coli DH5[aplha]. Couples of designed primers/probes were very specific and have been developed by taking advantage of the mosaic structure of the bacterial genome. The proposed approach is based on the over time measurements of the number of plasmids pB10 and its bacterial host DH5[alpha], where an increased ratio (pB10/DH5[alpha]) implies a release of the plasmid to the indigenous bacteria. This method was used to assess the impact of some environmental parameters on the release of DNA in complex microbial communities. Two groups of factors could be distinguished according to whether they influence the persistence of plasmid pB10 in communities in microcosms (oxygenation / mixing, addition of antibiotics at sub-inhibitory concentrations as amoxicillin and sulfamethoxazole frequently found in treatment plant) and / or they favor his release in bacterial communities (biofilms, sediments). Without inducing genes transfers, the antibiotics tested, even at sub-lethal concentrations, could participate in the dissemination of resistance genes by facilitating their persistence
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  • HAL Id : tel-01748556, version 1

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Sébastien Bonot. Persistance et dissémination du plasmide pB10, vecteur de gènes de résistance aux antibiotiques, dans des biomasses issues de stations d'épuration d'eaux usées urbaines. Médecine humaine et pathologie. Université Henri Poincaré - Nancy 1, 2010. Français. ⟨NNT : 2010NAN10050⟩. ⟨tel-01748556⟩

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