ANTIMUTAGENICITY OF WATER AND METHANOL EXTRACTS OF SOYMILKS FERMENTED BY BIFIDOBACTERIA AND LACTIC-ACID BACTERIA

An antimutagenic effect of the aqueous and 80% methanol extracts of soymilk was observed on N-methyl-N'-nitrosoguanidine (MNNG) mutagenesis toward Escherichia coli B/r WP2 trp-. Addition of both extracts to the plate decreased the mutation frequency through the dose amount of 60 mul. However, there was a tendency for the mutation frequency to increase with the addition of more than 80 mul. The effect of the extract prepared from soybeans soaked in water was increased by heating them at 100-degrees-C for more than 40 min. The 80% methanol extracts of soymilk fermented by Bifidobacteria adolescentis, B. breve, B. longum and Streptococcus lactis increased the antimutagenic effect compared with that of unfermented soymilk. The extract of fermented soymilk with B. infantis enhanced the MNNG mutagenesis toward E. coli. The antimutagenic effects of the fermented milk with B. bifidum, S. thermophilus and Lactobacillus acidophilus were lower than that of unfermented soymilk.