[EFFECT OF OSMOTIC AND OXIDATIVE STRESS ON STRAINS OF GENOVARIANTS OF VIBRIO CHOLERAE EL TOR BIOVAR].

Aim: Study the effect of osmotic and oxidative stress on survivability and changes in phenotypic and genetic properties of strains of genovariants of V. cholerae El Tor biovar.

Materials And Methods: 22 strains of V. cholerae El Tor biovar were used in the study. Phenotypic properties of strains were studied in LB medium with the addition of the appropriate ingredients. Surface structures of cells were studied using scanning probe microscope "Solver P47-PRO". PCR was carried out using specific primers in "Tercic" amplificator.

Results: After 60 minutes of incubation in 3 M solution of NaCl and after 6 minutes in 20 mM solution of hydrogen peroxide, the amount of surviving cells of genovariants was, respectively, 3.0 - 25.0 and 4.3 - 7.6 times higher than for typical strains. One of the mechanisms of increased resistance of genovariants to high concentrations of salt was associated with the production of an extra exopolysaccharide layer on the cell surface at earlier periods than in typical strains. Osmotic stress results in a reversible reduction of mobility in strains of genovariants of V. cholerae El Tor biovar. Osmotic and oxidative stress was revealed to result in a loss of a number of mobile genetic elements in strains of genovariants.

Conclusion: Genovariants of V. cholerae El Tor biovar, that had caused cholera outbreaks in Russia in 1993 -2001, in contrast to typical strains, isolated in 1970 - 1990, are more resistant to th effect of osmotic and oxidative stress, that, probably, facilitates their higher survivability in both the environment and macroorganism.