Morphology and enzyme activity of nonculturable forms of Vibrio cholerae

The transition of V. cholerae into the uncultivable state under experimental conditions was accompanied by gradual changes in their morphology, motility and metabolic activity. The vibrios took the oval form, lost their flagellum, motility and enzyme activity on diagnostic media. Dehydrogenase activity tested by reduction of triphenyl tetrazolium chloride, increased at the initial stages and dropped to the initial level or even lower by the end of the observation period (10 months). Similar dynamics was noted when the cytoplasmatic marker enzyme--ATPase activity was studied. Glucose catabolism in the uncultivable forms shifted towards glycolysis. During 1-2 months ctx and tcp genes could be detected in these forms by the PCR. The dynamics of the biological properties under study made it possible to find out the existence of 3 functionally different stages in the development of an uncultivable population.