Abstract
β-glucosidase, β-glucuronidase and nitroreductase activities of in vitro cultures of intestinal bacteria were compared with those of the caecal contents of gnotobiotic mice monoassociated with the same bacteria. Although bacterial enzyme activities detected in vitro were also detected in the caecal contents of monoassociated mice with each bacterium, activities of each bacterial enzyme in vivo were not always parallel to those in vitro. The difference of β-glucosidase activity among bacterial strains was smaller in the in vivo assay than that in vitro. Three enzyme activities in the caecal contents of gnotobiotic mice monoassociated with Eubacterium nitrogenes became stable more than 1 wk after inoculation, and were also changed by diets with different protein contents.