[Electron microscopic observations on the existence of "deflagellation tolerance" processes capable of explaining the selective isolation of vibrios in semisolid agar].

The authors identified a group of substances (flagellar depression factors--FDF) which suppress the mobility of enterobacteria (immobilization) but do not influence the Vibrio movements (tolerance). FDF do not affect the vital processes, multiplication and formation of colonies. Electron microscopic interpretation showed that, in the usual media, enterobacteria have characteristic peritrichous cilia, whereas in media with FDF they are denuded of their flagellation formation. As such a process of flagellation depletion seems to be not known, we suggest the term "deflagellation" to name it. In a completely different way, the vibrios keep their single cilium located apically and implicitly their moving ability. These behaviour differences are evident in semisolid agar with FDF. The deflagellated enterobacteria are, therefore, immobilized, and multiply, forming small punctual colonies, of 0.5-1 mm phi, whereas the vibrios tolerating FDF develop and at the same time move in the liquid agar, mass, forming large colonies, of 8-14 mm phi. The electron microscopic observations presented show the existence of a "deflagellation tolerance" process and also explain the specific typology of the colonies of vibrios and enterobacteria formed in liquid agar with FDF.