ISOLATION OF METHANOTROPHIC BACTERIA FROM NATURAL BIOCENOSES AND SELECTION OF NUTRIENT MEDIA OPTIMAL FOR CULTIVATION IN LABORATORY CONDITIONS

Background. One of the most pressing problems in the world is the production of food protein. The global protein deficit is estimated at 30 million tons per year, for the Russian Federation it is estimated at 2-2.5 million tons of protein per year. The problem of protein deficit can be partially solved with the help of methanotrophic bacteria. Under optimal conditions, methanotrophic bacteria are able to oxidise actively natural gas – methane and increase their biomass, rich in valuable protein, vitamins and other biologically active substances. The feed product from methanotrophic bacteria is comparable to fish meal and soybean meal, the concentration of pure protein in it is more than 80%. Purpose. Isolation of methanotrophic bacteria from natural biocenoses and their cultivation on various nutrient media in laboratory conditions. Materials and Methods. The study was conducted from 2019 to 2022 in the microbiological laboratory of the Center for Technological Excellence “Advanced Chemical and Biotechnology” of the Tolstoy Tula State Pedagogical University. The object of the study was methanotrophic bacteria isolated from various natural and artificial ecosystems, collection strains of Methylococcus capsulatus B-2990 and Methylomonas methanica B-2110. To isolate methanotrophic bacteria, the method of seeding a accumulative culture on a solid agiarized sterile nutrient medium in Petri dishes was used. For the cultivation of methanotrophs, nutrient media of various compositions containing all the necessary macro- and microelements for the normal growth of bacterial colonies were used. Results. Colonies of methanotrophic bacteria were found in one sample of bottom sediments taken from the sphagnum swamp of the village of Kochaki in the Tula region and in samples from a methane reactor. As a result of comparison of nutrient media for isolation and cultivation of methanotrophs, it was found that the most suitable medium for isolation of methanotrophic bacteria is the standard nitrate mineral medium NMS. For the cultivation of methanotrophic bacteria, the best media were: the nutrient medium with the addition of anaerobic sludge, the ammonium mineral nutrient medium (AMS), and AMS with addition of methanol, the nutrient medium No.221 with addition of methanol. Conclusions. The use of various nutrient media for the cultivation of methanotrophic bacteria makes it possible to assess the effect of various organic substances on the growth and development of bacteria