# Spatiotemporal Self-Organization of Fluctuating Bacterial Colonies

## TL;DR

This paper models bacterial colonies' spatiotemporal dynamics, revealing how fluctuations influence colony stability and movement, and connects these behaviors to biofilm life cycles using bifurcation and large deviation analysis.

## Contribution

It introduces a coupled model of motility-induced phase separation and population dynamics, highlighting the effects of fluctuations on colony metastability and spatial organization.

## Key findings

- Static colonies become metastable with fluctuations.
- Limit cycles lead to random colony formation locations.
- The model explains aspects of biofilm and planktonic life cycles.

## Abstract

We model an enclosed system of bacteria, whose motility-induced phase separation is coupled to slow population dynamics. Without noise, the system shows both static phase separation and a limit cycle, in which a rising global population causes a dense bacterial colony to form, which then declines by local cell death, before dispersing to re-initiate the cycle. Adding fluctuations, we find that static colonies are now metastable, moving between spatial locations via rare and strongly nonequilibrium pathways, whereas the limit cycle becomes almost periodic such that after each redispersion event the next colony forms in a random location. These results, which hint at some aspects of the biofilm-planktonic life cycle, can be explained by combining tools from large deviation theory with a bifurcation analysis in which the global population density plays the role of control parameter.