Optimal medium for growth and glycosidases production of Bacteroides JY-6, an human intestinal bacterium, was general anaerobic medium or tryptic soy broth containing sod ium thioglycolate and ascorbic acid. By cocultivation of Staphylococcus R-48, Bacteroides JY-6 could be cultured in LB broth unable to culture JY-6. Heated Staphylococcus R-48 was also the inducer of the production of Bacteroides JY-6 glycosidases. These glycosidases were induced well by natural flavonoid glycosides, such as poncirin, naringin and rutin, but were not by synthetic substrates, p-nitrophenyl ${eta$-D-glucopyranoside and p-nitrophenyl ${alpha}$-L-rhanmopyranoside.