dc.description.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. | |