[Phenotypic analysis of two morphologically different types of Vibrio cholerae 0139 colonies].

A clinical isolate Vibrio cholerae P16064 serogroup 0139 was shown to produce two different kinds of colonies: opaque encapsulated and translucent devoid of capsule. Low virulence of translucent colonies seems to be due to not only loss of capsule which determines serum resistance, but also to decreased expression of genes controlling the motility, and production of protease and mannose-sensitive adhesion pili. Analysis of the lysogenic properties of the two types of colonies permitted us to propose that simultaneous spontaneous alteration of capsule production and the above-mentioned virulence factors in translucent colonies may be caused by a temperate phage in turbid clones of strain P16064.