Collective behavior of quorum-sensing run-and-tumble particles in confinement

TL;DR

This paper investigates how quorum-sensing bacteria in confined spaces form clusters or rings due to signaling molecules affecting their motility, revealing a behavior distinct from traditional phase separation.

Contribution

It introduces a generic model for quorum-sensing bacteria in confinement, analyzing aggregation phenomena driven by signaling molecules with analytical and numerical methods.

Findings

Bacteria form stationary clusters or rings depending on the signaling protocol.

Aggregation is fundamentally different from standard motility-induced phase separation.

The model captures the long-range effects of signaling molecules on collective behavior.

Abstract

We study a generic model for quorum-sensing bacteria in circular confinement. Every bacterium produces signaling molecules, the local concentration of which triggers a response when a certain threshold is reached. If this response lowers the motility then an aggregation of bacteria occurs, which differs fundamentally from standard motility-induced phase separation due to the long-ranged nature of the concentration of signal molecules. We analyze this phenomenon analytically and by numerical simulations employing two different protocols leading to stationary cluster and ring morphologies, respectively.