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Article Dans Une Revue Interface Focus Année : 2014

On growth and form of Bacillus subtilis biofilms

Résumé

A general feature of mature biofilms is their highly heterogeneous architecture that partitions the microbial city into sectors with specific micro-environments. To understand how this heterogeneity arises, we have investigated the for- mation of a microbial community of the model organism Bacillus subtilis. We first show that the growth of macroscopic colonies is inhibited by the accumulation of ammoniacal by-products. By constraining biofilms to grow approximately as two-dimensional layers, we then find that the bacteria which differentiate to produce extracellular polymeric substances form tightly packed bacterial chains. In addition to the process of cellular chaining, the bio- mass stickiness also strongly hinders the reorganization of cells within the biofilm. Based on these observations, we then write a biomechanical model for the growth of the biofilm where the cell density is constant and the physical mechanism responsible for the spreading of the biomass is the pressure gener- ated by the division of the bacteria. Besides reproducing the velocity field of the biomass across the biofilm, the model predicts that, although bacteria divide everywhere in the biofilm, fluctuations in the growth rates of the bacteria lead to a coarsening of the growing bacterial layer. This process of kin- etic roughening ultimately leads to the formation of a rough biofilm surface exhibiting self-similar properties. Experimental measurements of the biofilm texture confirm these predictions.
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Dates et versions

hal-02326483 , version 1 (22-10-2019)

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Julien Dervaux, Juan Carmelo Magniez, Albert Libchaber. On growth and form of Bacillus subtilis biofilms. Interface Focus, 2014, 4 (6), pp.20130051. ⟨10.1098/rsfs.2013.0051⟩. ⟨hal-02326483⟩
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