[Determination of DNA content in individual Vibrjo cholerae cells by using flow cytofluorimetry method: comparative analysis of inhomogeneity in cells of strains with various biological properties].

Aim: Comparative analysis of DNA content in individual cells of Vibrio cholerae strains with various biological properties.

Materials And Methods: 24-hour agar cultures of 2 avirulent (lacking cholera toxin gene) and 2 virulent strains and their subcultures obtained by cultivation in 1% peptone water for 1, 3 and 5 hours were studied. DNA of the killed bacteria was dyed by a mixture of ethidium bromide and mitramycin. Ratio of cells with low, intermediate and high relative DNA content in conditional units of specific DNA fluorescence intensity was determined by flow cytofluorimetry method. The degree of inhomogeneity of the studied microbial population cells was evaluated by DNA histogram variation coefficient value.

Results: At the level of major statistical samples of individual V. cholerae cells a principally different reaction pattern of the studied toxigenic and non-toxigenic strains on changes of cultivation conditions was registered.

Conclusion: Populations of cells of toxigenic V. cholerae strains in contrast to non-toxigenic probably shift to polyploid state during starvation. This phenomenon may turn out to be a differential feature in determination of the risk group (hazard) of a strain.