The mutual behavior of strains is more or less similar on both substrates tested, rich (NAG) and minimal (MMA); the only expected

exception is the submissive role of F on MMA whose growth is dependent on the presence of helpers. It is conspicuous that the role of F is fully taken by its daughter morphotype M. As already mentioned above, the behavior of particular strains in liquid media provides no guide for predicting their behavior on solid substrates: the two kinds of media represent to a great extent alternative, and incompatible, strategies of growth. Why multicellular bacteria? If we take axenic bacterial 4EGI-1 purchase colonies as analogues of clonal body of multicellular eukaryots, two problems will come out immediately: the objective of building such a body, and the high plasticity of bacterial ontogenies. As far as we know, colonies of Serratia never produce reproductive organs: they can safeguard their propagation without any demanding, and coordinated, activity of colony building. Why, then, do they go into the trouble with elaborate microscopic filigree of terraces and scouts, and even macroscopic patterning and ornamentation? The answer may lie in physiological division of labor [4] and perhaps

even “histological” differences across the colony. Besides plastic responses, bacteria can – reversibly or irreversibly – diversify Dinaciclib concentration also genetically into Ilomastat price different morphotypes, depending on conditions like those mentioned above. In Paenibacillus repeated and heritable switches between different morphotypes are induced by the density of agar [43–45]. Genetic differentiation was also often described in suspension cultures. For example a clone of Pseudomoas aeruginosa differentiated quickly and apparently purposelessly into multiple genetic variants [46]. The authors ascribe the phenomenon MAPK inhibitor to an “insurance effect” preparing the lineage

to conditions that may set in the future. A similar effect in Serratia is believed to play a role in colonization of new niches [47]. Finally, a clonal population may break into different specialized clones evoked by metabolic demands [48, 49] or antibiotic pressure [50]. However, since our clones were genetically stable in respect to the observed characteristics, and since all morphogenetic variation was found to be fully reversible, we can exclude such genetic switches, as well participation of phages, plasmids, transposons or similar elements, in our model and ascribe all variations observed (like colony patterning, scouting, or response to neighbors and environmental cues) solely to phenotypic plasticity. Conclusions Multicellular bacterial models (colonies) match their eukaryotic counterparts (animals, plants, fungi) in areas of research classically focused only to eukaryotes: 1. Axenic (“germ-free”) and gnotobiotic settings are easy to establish, and interactions within the body, as well as between different bodies (of the same, or different lineages) can be studied to minute details.