Mécanismes de l'inhibition de la croissance par l'acétate chez Escherichia coli

Abstract : Acetate inhibits the growth of Escherichia coli on glucose. Despite many studies that have attempted to elucidate the underlying mechanisms, we are currently unable to provide a comprehensive explanation of this phenomenon. Here, we construct a series of isogenic mutants that inactivate specific parts of the metabolic pathways of acetate. By systematically measuring growth rate, as well as the fluxes of carbon metabolites entering and leaving the cell, we are able to propose an explanation for the growth inhibition by acetate. The Pta-AckA pathway contributes about 20% of the growth inhibition by acetate, probably through the action of acetyl-phosphate on gene expression or the regulation of enzyme activities. We also show that acetate does not function as a classical uncoupling agent. This mechanism was commonly assumed to account for the largest part of acetate inhibition. Our data support a model where the imbalance of cellular anions, caused by the massive influx of acetate into the cell, is the major determinant of growth inhibition by acetate. We also present two synthetic biology projects from the iGEM competition: one to quantify mercury in a water sample and the other controlling the number of living cells by light in a bacterial population.
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Stéphane Pinhal. Mécanismes de l'inhibition de la croissance par l'acétate chez Escherichia coli. Physique [physics]. Université Grenoble Alpes, 2015. Français. ⟨NNT : 2015GREAV003⟩. ⟨tel-01178817⟩

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