Microbiota of goby fish in the northern part of the Caspian sea

Microorganisms, including bacteria of aquatic ecosystems, due to their short life cycle and rapid reproduction, react to any transformations of environmental conditions earlier than other organisms of any biocenosis. Various qualitative and quantitative changes in the bacteriocenoses of water and bottom sediments entail changes in the microbiota of aquatic organisms. Fish of the Gobiidae family, due to their sedentary lifestyle, can serve as an indicator of changes in the microbiota of the environment through the transformation of their own. The results of microbiological studies of goby fish caught in the northern part of the Caspian Sea in 2014–2023 are presented. The microbiota of organs and tissues of gobies changed insignificantly over the years at the level of the isolated families; microbial associations were similar in summer and autumn. In the autumn period, the qualitative composition of bacteriocenoses of all studied biotopes became more diverse in terms of the number of isolated genera of bacteria. Isolated microorganisms of gobies are represented by gram-positive and gram-negative forms with a dominance of representatives of the family. Enterobacteriaceae and gram-positive rods and cocci. The isolated bacteria had enzymatic activity — the production of a wide range of enzymes was recorded, including enzymes acting as pathogenicity factors. The presence of resistant isolates to most of the tested antibiotics was also noted. The above properties indicated significant heterogeneity of the population of isolated bacteria and their significant adaptive potential. The results obtained indicated the persistence of potentially dangerous microorganisms in gobies. The absence of clinical signs of infectious diseases and any pathological processes in the organs and tissues of the examined fish made it possible to assess the presence of the above microorganisms as asymptomatic bacterial carriage