Run-and-tumble bacterial chemotaxis in confinement

Most microswimmers like bacteria have evolved and live in complex porous materials such as tissues or soil, yet their motion and chemotaxis in confinement are still not completely understood. We present a run-and-tumble model for confined bacterial motion model coupled to the chemical gradient of externally-supplied exygen gradient which affects the bacterial motility. We present simulations of the collective chemotactic behavior in various sizes of confinement, various susceptibility to the oxygen gradient, and various population densities, and discuss the states observed for these parameters. Last we discuss the phase separation of such chemotactic bacteria in confinement and connect the results to recent experimental observations.