Abstract
Urease activities of anaerobic bacteria that constituted predominant gut flora were examined. It was demonstrated that some strains of Eubacterium aerofaciens, E. lentum, and Peptostreptococcus products produced urease. They were the most numerous species in human feces. All strains of Bifidobacterium infantis and some strains of Bacteroides multiacidus, B. bifidum, Clostridium symbiosum, Fusobacterium necrophorum, F. varium, Lactobacillus fermentum, Peptococcus asaccharolyticus, and P. prevotii produced urease. The optimum pH of the Lactobacillus urease was found to be 4.0, whereas the pH value of B. multiacidus urease was 8.0.