Lactobacillus paraplantarum KM (Lp), Weissella sp. 33 (Ws), and Enterococcus faecium 35 (Ef) were used in single (Lp, Ws, Ef) or mixed cultures (Lp+Ws, Lp+Ef, Ws+Ef) for soy milk fermentation ($37^{circ}C$, 12 h). After 12 h, the cell numbers, pH, and TA of soymilk were $7.4{ imes}10^8-6.0{ imes}10^9CFU/ml$, 3.8-4.5, and 0.59-0.70%, respectively. Changes in the contents of glycitin and genistin in soymilk fermented with Ef were not significant. The contents of isoflavone glucosides in soymilk fermented with the other cultures decreased significantly with an increase of aglycone contents (p<0.05). It corresponded well with a sharp increase in ${eta}$-glucosidase activity during fermentation. About 92-100% of the daidzin and 98-100% of the genistin in soymilk were converted to corresponding aglycones by Lp, Ws, or Lp+Ef within 12 h.