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Etude de l’hétérogénéité métabolique chez la bactérie Escherichia coli lors de sa croissance en mélange glucose/xylose

Abstract : Escherichia coli, naturally living in the intestinal flora, is subject to large fluctuations in the nature and quantity of the nutrients availability. Multiple carbon sources are sequentially consume with cells exhibiting transition phases between each substrate consumption. Cellular adaptation during these transitional phases has long been considered homogeneous within the population, while recent studies suggest cell-to-cell phenotypic variability during transition. The mechanisms behind this variability remain only partially elucidated. Our study focuses on the adaptation of cells during growth on glucose and xylose mix. This mixture of substrates is of interest in the context of plant biomass valorization. We developed a methodology allowing phenotypic variability observation in a population of Escherichia coli during growth on a glucose/xylose mixture. Through this method, we highlighted the role and importance of the transcription factor XylR in the duration of the glucose/xylose transition. Thus, the latency duration between glucose and xylose consumption has been shown to be flexible and impacted by the availability of XylR. When this availability is insufficient, the major part of the cell are not able to restart a new metabolic program, creating a heterogeneity in the population between cells that have adapted and the others. Finally, we explored the phenotypic properties of the two subpopulations and showed that unadapted cells enter a dormant-like state. Transcriptional program changes during glucose/xylose transition were also characterized by a transcriptomic study. This work provide the first exhaustive description of the glucose-xylose transition and illustrates the possibility of creating phenotypic bistability in a population by playing on the availability of a single transcription factor.
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Submitted on : Wednesday, March 30, 2022 - 5:26:09 PM
Last modification on : Monday, April 4, 2022 - 3:24:40 PM

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  • HAL Id : tel-03625250, version 1

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Manon Barthe. Etude de l’hétérogénéité métabolique chez la bactérie Escherichia coli lors de sa croissance en mélange glucose/xylose. Biochimie [q-bio.BM]. INSA de Toulouse, 2021. Français. ⟨NNT : 2021ISAT0024⟩. ⟨tel-03625250⟩

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