Patterning of mutually interacting bacterial bodies: close contacts and airborne signals

Colonies are shaped by both autonomous patterning and by signals generated by co-habitants of the morphogenetic space, mediating both internal shaping of the body, and communication between bodies sharing the same living space. The result of development is affected by the overall distribution of neighbors in the dish. The neighbors' presence is communicated via at least two putative signals, while additional signals may be involved in generating some unusual patterns observed upon encounters of different clones. A formal model accounting for some aspects of colony morphogenesis and inter-colony interactions is proposed.The complex patterns of color and texture observed in Serratia rubidaea colonies may be based on at least two signals produced by cells, one of them diffusing through the substrate (agar) and the other carried by a volatile compound and absorbed into the substrate. Differences between clones with regard to the interpretation of signals may result from different sensitivity to signal threshold(s).Bacteria can display a plethora of multicellular forms (colonies, mats, stromatolites, etc.); their structure and appearance depends on factors such as the presence of nutrients or neighbors. Concepts of "body" and "community", as developed for multicellular sexual eukaryots, became, however, somewhat blurred upon attempts of their application to microorganisms. Is differentiation of multicellular units in bacteria comparable to embryonic development, to the establishment of an ecosystem? Is it even the place of Darwinian evolution on a micro-scale?Multicellular bacterial bodies can be viewed as ecosystems negotiated by myriads of (presumably genetically different and selfish) specialists (e.g. [1-6]). Each cell is understood as an individual playing its own game according to resources, energy costs, and complicated informational interactions with others. However, patterning of multicellular bodies remains beyond interest, at the most being viewed as a passive