CONSERVATION OF CHOLERA VIBRIOS IN COMPLEX MICROCOSM CONTAINING GREEN MICROALGAE

Abstract

BACKGROUND. In the summer-autumn period, the peak of reproduction and flowering of phytoplankton occurs, as a result of which, during this period, a deterioration in the quality of river water is noted. At the same time, cases of gastrointestinal diseases in humans are recorded, and epidemic complications of cholera may occur in endemic areas. The formation of biofilm forms by V. cholerae on the surface of chitinous hydrobionts and plastic components can lead to the spread of V. cholerae and possibly explains the autochthonous mechanism of their existence in water bodies. AIM to determine the duration of vibrio cholerae preservation on biotic (chitin) and abiotic (plastic) substrates in the presence of green unicellular algae with a change in cultivation temperature, under experimental conditions. MATERIALS AND METHODS. to achieve this goal, bacteriological and molecular genetic methods were used. RESULTS. It was shown that the preservation of toxigenic and non-toxigenic strains of V. cholerae O1 El Tor and V. cholerae O139 (ctxAB+ tcpA+csh1- and ctxA tcpAcsh1+) for six months, including three months at a low temperature simulating autumn winter period, as part of biofilms in microcosms, where one of the components is green microalgae. We noted an excess of the concentration of V. cholerae O1 and O139 serogroups by two orders of magnitude in samples, where one of the components is chitin and the reproduction of green microalgae in the presence of a chitin substrate, which is probably one of the stages of the food chain in the ecology of water bodies and, accordingly, can be a reservoir for biofilm forms of cholera vibrios. Preservation of V. cholerae O1 El Tor non-toxigenic strain in a viable state in biofilm samples on plastic at a decrease in temperature to 8 2C for three months is possibly due to the presence of a cold shock gene in its genome. CONCLUSION. Without a substrate for adhesion, colonization and biofilm formation, vibrios are not capable of long-term persistence at low temperatures