COOPERATIVE STRATEGIES IN FORMATION OF COMPLEX BACTERIAL PATTERNS

In nature, bacterial colonies often must cope with hostile environment al conditions. To do so they have developed sophisticated cooperative behavior and intricate communication channels on all levels. The resul t is that a profusion of complex patterns are formed during growth of various bacterial strains and for different environmental conditions. Some qualitative features of the complex morphologies may be accounted for by invoking ideas from pattern formation in non-living systems to gether with a simplified model of chemotactic ''feedback''. We present a non-local communicating walkers model to study the effect of local bacterium-bacterium interaction and communication via chemotaxis signa ling. The model is an hybridization of the continuous approach (to han dle chemicals' diffusion) and the atomistic approach (each ''atom'' or ''walker'' represents 10(4)-10(5) bacteria). Using the model we demon strate how communication enables the colony to develop complex pattern s in response to adverse growth conditions. Efficient response of the colony requires self-organization on all levels, which can be achieved only via cooperative behavior of the bacteria. It can be viewed as th e action of an interplay between the micro-level (the individual bacte rium) and the macro-level (the colony) in the determination of the eme rging pattern. We show that seemingly unrelated patterns can result fr om the employment of the same generic strategies.