The possibility of submerged со-cultivation of the basidiomycetes Flammulina velutipes, Ganoderma lucidum and Pleurotus ostreatus with the bacteria Azospirillum brasilense was demonstrated, and optimal conditions for the process were selected. The azospirilla strains under study had active mobility and formed clusters near mushroom hyphae in liquid co-cultures optimized both in medium composition and bacterial inoculum concentration. The concentration of bacterial cells, ceteris paribus, had a significant effect on the growth of binary cultures. Co-cultivation of F. velutipes with A. brasilense Sp245 at the optimal bacteria concentration (0.5% v/v) in the inoculum (A600 = 1.0) made it possible to obtain 2.35 times more dry biomass than in the control. The intensive growth of the mixed culture of mushrooms with the studied azospirilla was promoted by the medium based on Glc and Fru (in mass proportion 1:1), and Asn. The characteristics of the development of P. ostreatus fruit bodies and the reduction of contamination in the presence of azospirillum were evaluated. Mixed bacterial-fungal cultures of P. ostreatus with A. brasilense SR80 which were used as seeding material were most efficient in the accumulation of submerged mycelial biomass, the rate of grain substrate colonization and intensity of fruit-body formation. Data obtained allow us to judge the high potential of using binary mushroom-bacterial cultures for the efficient production of mycelial biomass and fruiting of basidiomycetes. Flammulina, Ganoderma, Pleurotus, Azospirillum, co-culture, submerged culture, fruiting The work was funded on the theme АААА-А17-117102740098-8.