An Individual-Based Model for Biofilm Formation at Liquid Surfaces Arxiv
An individual-based model for biofilm formation at liquid surfaces Maxime Ardré+,∗,o, Hervé Henry+, Carine Douarche∗, Mathis Plapp+ + Laboratoire PMC, Ecole Polytechnique CNRS, Palaiseau, France ∗ Laboratoire de Physique des Solides, Université Paris-Sud CNRS, Orsay, France o Laboratoire de Physique Statistique, ENS CNRS, Paris, France May 7, 2018 Abstract The bacterium Bacilus subtilis frequently forms biofilms at the interface between the culture medium and the air. We develop a mathematical model that couples a description of bacteria as individ- ual discrete objects to the standard advection-diffusion equations for the environment. The model takes into account two different bacte- rial phenotypes. In the motile state, bacteria swim and perform a run-and-tumble motion that is biased toward regions of high oxygen concentration (aerotaxis). In the matrix-producer state they excrete extracellular polymers, which allows them to connect to other bacteria and to form a biofilm. Bacteria are also advected by the fluid, and can trigger bioconvection. Numerical simulations of the model reproduce all the stages of biofilm formation observed in laboratory experiments. Finally, we study the influence of various model parameters on the dy- namics and morphology of biofilms. 1 Introduction arXiv:1512.04697v1 [q-bio.CB] 15 Dec 2015 Bacteria are unicellular prokaryotic microorganisms. They are ubiquitous and constitute a large part of the terrestrial biomass. Bacteria can live as individual cells during the planktonic phase. However, most of the time, they are part of self-organized communities of complex architecture adsorbed on interfaces: the biofilms. Besides the bacteria themselves, biofilms are mostly made of an extracellular matrix composed of macromolecules [1, 2, 3] that are produced by the bacteria and lead to cohesive interactions between them 1 [4, 5].
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