We have studied the proteolytic, α-galactosidase, and β-glucosidase activities of the consortia Lactobacillus acidophilus 317/402 with Bifidobacterium longum-Ya3 and Вifidobacterium adolescentis-С52 in the process of soy milk fermentation. It has been established that the studied cultures possess active enzyme apparatuses and help minimize those factors that limit the use of soy milk for the production of functional foods ‒ the presence of indigestible oligosaccharides and a legume taste. In terms of the proteolytic activity, which was 30 mU in 6 hours, the consortium Lactobacillus acidophilus 317/402 with Bifidobacterium adolescentis-С52 was the leader. The largest α-galactosidase and β-glucosidase activities, 98 U/mg and 81 U/mg, respectively, were demonstrated by the consortium Lactobacillus acidophilus 317/402 with Bifidobacterium longum-Ya3. At the same time, the amount of daidzin, glycitin, and genistin decreased by 93 %, 75 %, and 99.6%, respectively, while the amount of relevant aglycones increased by 278 %, 153 %, and 338 %. The specified enzyme activities of Lactobacillus acidophilus 317/402 with Вifidobacterium adolescentis-С52 did not exceed 78 and 75 U/mg, respectively, while the biotransformation processes of isoflavones were less intensive. It has been shown that certain symbiotic relationships between the selected strains of Bifidobacterium and Lactobacillus acidophilus are formed in soybean milk, which makes it possible to obtain high titers of probiotic cultures in the finished product, with the predominance of Bifidobacterium. After 9 hours of fermentation, the average number of Bifidobacterium and lactobacillus cells for both consortia was (0.9–2)·10 8 CFU/cm 3 and (0.8–4)·10 9 CFU/cm 3 , respectively. We have proven the increase in the probiotic and estrogenic activity of fermented drinks based on soy while reducing the amount of galactooligosaccharides by 50‒70 % on average.