The goal of this investigation was to study the structure and biological properties (antilysozymic, activity and biofilm formation) of gram-negative bacteria isolated from Bithyniidae mollusks and their habitat (water reservoir waters and soil). A total of 160 gram-negative bacterial strains isolated from the mollusks of the Bithyniidae family and their habitat were the material to be, studied. Psedomonas, Comamonas, and Acinetobacter held the lead in the structure of microbiocenosis of Bithyniidae mollusks, the first intermediate host of Opisthorchis filineus, while Acinetobacter did in the habitat. The antilysozymic activity of the water strains was shown to be an order of magnitude higher than that of the strains isolated from the mollusks.