INHIBITORY EFFECTS OF FECAL LACTOBACILLI AND BIFIDOBACTERIA ON THE MUTAGENICITIES OF TRP-P-2 AND IQ

Thirty-one strains of Lactobacillus sp. and Bifidobacterium sp. isolat ed from the feces of human subjects who had consumed fermented milk wi th Lactobacillus acidophilus LA-2 were tested for the desmutagenic pro perties against the mutagenicity of 3-amino-1-methyl-5H-pyrido [4,3-b] indole (Trp-P-2) and 2-amino-3-methyl-3H-imidazo [4,5-f] quinoline (I Q) using Salmonella typhimurium TA 98 as an indicator bacterium. Each of the tested fecal bacteria exhibited their characteristic inhibitory effects of 0.5-82.0% and 0.4-63.9% against the mutagenicities of Trp- P-2 and IQ, respectively. Among the tested fecal isolates and those br iefly identified as L. fermentum, L. rhamnosus and L. salivarius appar ently suppressed above 50% of the mutagenicity of Trp-P-2 and IQ in th e assay with S-9 mix. Especially, strain L. rhamnosus 3K21 showed high est desmutagenicities of 82.0% and 63.9% toward Trp-P-2 and IQ, respec tively. The dose-response of the antimutagenicities of L. rhamnosus 3K 21 strain toward Trp-P-2 and IQ depended on concentration of intact ce lls. Counts of fecal bifidobacteria and lactobacilli were increased du ring the administration of fermented milk.