AGGREGATION PATTERNS IN STRESSED BACTERIA

We study the formation of spot patterns seen in bacterial colonies whe n the bacteria are subjected to oxidative stress due to hazardous by-p roducts of respiration. The cell density is coupled to a chemoattracta nt concentration as well as to nutrient and waste fields. The model co mbines the propagation of a front of motile bacterial radially outward from an initial site, a Turing instability of the uniformly dense sta te, and a reduction of motility for cells sufficiently far behind the front. The wide variety of patterns seen in the experiments is reprodu ced by the model by varying the details of the initiation of the chemo attractant emission as well as the transition to a nonmotile phase.