Motility-Induced Phase Separation in Signalling Bacteria #

Wesley Ridgway

11:50 Wednesday in 4Q56.

Part of the Asymptotics in active matter session.

Abstract #

Motility-induced phase separation (MIPS) is a generic feature of systems of interacting self-propelled particles, with relevance across developmental biology, microbiology and bioengineering. There is well developed theory for how physical interactions drive self-organization and pattern formation through MIPS. However, despite the importance of intercellular signalling in biological contexts, much less is known about pattern formation in systems of motile, chemically interacting constituents.

In this talk, we derive and investigate a multiscale continuum model for a motile, chemically interacting population of bacteria that communicate via quorum sensing. Our model accounts explicitly for the cell-level genetic regulation of motility and signal production using a chemically structured approach. We develop a WKBJ-like technique that can be applied to an asymptotic regularization of the model, physically corresponding to the limit of a small stochastic component in the gene-regulatory network. We use this technique to determine a criterion for the onset of MIPS in the population, uncovering a novel type of instability that cannot arise through physical interactions alone.