Orateur
Description
We study the emergence of symmetry breaking in expanding bacterial colonies in the presence of a localized prey. While colony expansion is typically radially symmetric, environmental interactions can induce anisotropic propagation patterns. We introduce a kinetic reaction–transport model for motile and proliferating bacteria, combining persistent motion, stochastic reorientation, and division at the microscopic scale. From this description, we derive macroscopic equations for the bacterial density, leading to a nonlinear system governing colony dynamics. We analyze front propagation through travelling wave solutions and associated spreading speeds. We show that the presence of a prey alters the effective transport and proliferation terms, resulting in changes in front speed and triggering a breakdown of radial symmetry. Our approach combines analytical results, numerical simulations, and experimental data at both the colony and single-cell scales.
This work is carried out in collaboration with Vincent Calvez.