By coculturing E. coli HGU-3 with Bifidobacterium KH-2 or Streptococcus faecalis HGO-7 with Bifidobacterium KH-2, the productivity of $eta$-glucuronidase and $eta$-glucosidase was inhibited. When lactulose, growth factor of lactic acid bacteria, was added into this medium, the productivity of these enzymes and pH of the medium were dramatically decreased. When intestinal microflora of human and rat were inoculated in the medium containing lactulose, the enyzme productivity and pH of the medium were dramatically decreased. By s.c. injecting DMH into mice, $eta$-glucuronidase of intestinal bacteria was induced, but the production of the enzymes was inhibited by adminstering lactulose.