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Analyse de la séquence génomique et Etude de l'adaptation à l'acidité de L. delbrueckii ssp. bulgaricus ATCC11842

Stéphanie Penaud 
Abstract : The work described here began at a moment when few genetic data about Lactobacillus delbrueckii ssp. bulgaricus (L. bulgaricus) were available. Genome of the strain ATCC 11842, in collaboration with the Genoscope, was being sequenced. The first part of this thesis describes the genome annotation and analyse. This analyse suggest that L. bulgaricus is going on a specialisation to a restricted ecological area, the milk medium. It also reveals that L. bulgaricus has few regulation systems and resistance mechanisms to environmental stresses. This results led us to make the hypothesis that L. bulgaricus is a good model to identify important mechanisms for the acid tolerance response (ATR). The second part of the thesis describes the studies carried on the ATR of L. bulgaricus by complementary approaches. Transcriptomic results show that expression of 20% of the regulators and 50% of the ion transporters of the genome was modified by ATR. Nevertheless, none of the 5 s factor nor of the 5 two-component system present a variable expression. The proteomic analyse show that 19 proteins have their amount affected by ATR, among which chaperones and proteins involved in fatty acids biosynthesis. All together, our results suggest that ATR of L. bulgaricus needs several regulators, transcriptional attenuation mechanisms and post-transcriptional and post-traductional regulations. These preliminary results needs complementary analyses to determine which part of the visualised responses is really necessary for the increased resistance to acid stress after adaptation.
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Submitted on : Tuesday, April 3, 2007 - 8:00:00 AM
Last modification on : Monday, October 19, 2020 - 11:07:57 AM
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  • HAL Id : pastel-00002283, version 1



Stéphanie Penaud. Analyse de la séquence génomique et Etude de l'adaptation à l'acidité de L. delbrueckii ssp. bulgaricus ATCC11842. Life Sciences [q-bio]. INAPG (AgroParisTech), 2006. English. ⟨NNT : 2006INAP0013⟩. ⟨pastel-00002283⟩



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