Halotolerance Aeromonads Isolated From Water and Perch (Sander Lucioperca) in the Delta of the Volga River

Abstract

The article presents the results of a study of halotolerance in aeromonads isolated from 447 specimens of perch (Sander lucioperca) and 375 water samples in areas of its habitat in the delta of the Volga River. They were subdominant in the microbial landscape of these biotopes. There were no significant differences inoculation aeromonads found in various parts of the delta. Their halotolerance was studied by means of inoculation of daily pure cultures of meat--peptone broth with 3, 7 and 10% of sodium chloride content and incubation at 37◦C. All the studied microflora of this spieces was established to have significant indices of halotolerance with a predominance in water isolates. Whereby in cases of 3.0 and 7.0% NaCl concentrations were 2.2 times more and in the 10.0% NaCl solution with water and fish strains had similar indices, showing them to be of “marine origin”. Among isolated aeromonads, shattering the water and fish most halophilic strains of A. hydrophila and A. sobria, and halophobic strains were presented by A. caviae. As a rule, water strains had stability indices above in the average of 1.3 times higher than fish ones. Epidemiologically important strains of A. sobria were isolated from water more frequently than from fish, whereas A. hydrophila was isolated as in water as in fish at the same level. Halotolerance of isolated aeromonads in hydroecosystems of the delta of the Volga River had seasonal specificity and dynamics. The gain in halotolerance in aquatic strains of aeromonads in spring and autumn was caused by natural and climatic processes and the elevation in the salinity of delta waters. Enhanced halophilic strains of fish in these seasons is determined by their migration with fish, because in seasons pike migrates from the sea to the river ecosystem.