BIOANTIMUTAGENIC EFFECT OF THE CULTURE LIQUID OF STREPTOCOCCUS-FAECALIS ON MUTAGENESIS INDUCED BY 2-NITROFLUORENE IN SALMONELLA-TYPHIMURIUMTA-1538 AND TA-98

Streptococcus faecalis growing in rich organic media or synthetic medi um containing 0.1% trypton and 0.05% yeast extract was shown to form s ubstances with bioantimutagenic activity against the mutagenicity of 2 -nitrofluorene and 4-nitroquinoline-1-oxide, which induce frameshift a nd base-pair substitution mutations, respectively. The maximum accumul ation of antimutagens in the medium was observed within 16-24 h of gro wth. A modified Ames test showed that the culture liquid of Str. faeca lis possessed higher antimutagenic activity for Salmonella typhimurium strain TA 1538 than for strain TA 98 with an enhanced SOS response. F ractionation of the culture liquid revealed that the bioantimutagenic activity is localized in the fraction of peptides with molecular masse s of less than 12 kDa.