Diversité phénotypique et adaptation chez Escherichia Coli étudiées en millifluidique digitale

Abstract : Bacteria play a major role in our environment. Their ubiquity comes from their amazing ability to adapt to environmental conditions. Understand their adaptability can help to cure infections or to use bacteria for biotechnology. The diversity of phenotypes within a population - different observable characters - and the diversification mechanisms contribute to the bacterial adaptability. In order to study the adaptation of bacteria, we followed the temporal evolution of diversity within populations of Escherichia coli through environmental transition. We get a picture of the diversity with a phenotyping tool in millifluidic allowing parallel acquisition of one thousand the bacteria growth curves. Through three examples, we show the potential of this approach to read the phenotypes within a population and we explore the roles of diversification and Darwinian selection on the dynamics of adaptation observed. The phase variation of the ag43 gene and the exposure to a non lethal concentration of antibiotic illustrate a first phase of adaptation governed by the competition between the phenotypes with the highest apparition probabilities. Finally we study the adaptation of a population in a depleted environment for thirty days. After fifteen days we observe a convergence towards a single phenotype. This determinism is common to all three examples. However, the end of the experiment is unpredictable: the observation is different for each repetition. It corresponds to a second phase of adaptation which is dominated by the rare appearance of beneficial mutations.
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https://pastel.archives-ouvertes.fr/pastel-00981358
Contributor : Denis Cottinet <>
Submitted on : Tuesday, April 22, 2014 - 9:57:26 AM
Last modification on : Thursday, July 4, 2019 - 11:00:05 AM
Long-term archiving on : Monday, April 10, 2017 - 4:16:21 PM

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  • HAL Id : pastel-00981358, version 1

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Denis Cottinet. Diversité phénotypique et adaptation chez Escherichia Coli étudiées en millifluidique digitale. Biophysique. Université Pierre et Marie Curie - Paris VI, 2013. Français. ⟨pastel-00981358⟩

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