Study of microbiocenosis of fish gills and intestines in their cultivation using preparations based on bacteriophages

Nowadays bacteriophages are widely used in veterinary medicine, bio-technology, agriculture and in particular in aquaculture. Narrow specificity affecting the bacterial microflora and selective influence on the pathogenic and opportunistic microorganisms allow using the bacteriophages for diagnosing, preventing and treating the diseases of farm animals and fish. The emergence of antibiotic-resistant strains of microorganisms involves the search for new drugs to combat them. In this regard, phage therapy is an alternative to antimicrobial treatment of bacterial diseases of animals and fish. Despite the lack of data on the bacteriophage-based drugs applications in aquaculture, this direction is found to be promising and relevant. There is given a comparative analysis of the microbiocenosis of the gills and intestines of two-year-olds of red tilapia farmed in the water with adding the poly-valence pyobacteriophage and fed by compound feed treated by the preparation. It has been found that the dominant position in the intestinal microbiocenosis of red tilapia belongs to Micrococcus bacteria, whose share made 45.7% of all isolates of the gastrointestinal tract. By the frequency of occurrence, the second place is taken by the Bacterium species (33.2%), the third place - Staphylococcus (16.1%) species. The remaining groups of intestinal microorganisms are presented by a significantly number of isolates. It has been stated that the gills microflora was represented by a smaller species composition compared to the digestive tract microbiota. Isolates of the Bacterium and Staphylococcus bacteria were dominating, while the Actinomycetales and Bacillus microorganisms were represented in smaller numbers (1-2 colonies). The addition of a bacteriophage to water and its processing of compound feed helps to reduce the contamination of gills and reduce pathogenic microflora in the intestines of fish.