Antimutagenic Activity of Milk Fermented by Streptococcus thermophilus and Lactobacillus bulgaricus

Abstract

Antimutagenic activity of acetone or ethylacetate extracts of skim milk fer- mented by Streptococcus thermophilus, Lactobacillus bulgaricus, or a combma- tion of both the organisms was studied using Salmonella iyphimurium (TA 98 and TA 100). Mutagens used were 4-nitroquinoline-N-oxide (a direct-acting mutagen) and 2-aminofluorene (a muta- gen requiring S9 activation). Extracts from all fermented milks showed signifi- cant (P<.O5) dose response in suppressing the number of revertants caused by NQNO and 2-aminofluorene in both tester strains, whereas extracts from un- fermented milk had no effect. Extracts prepared from milk fermented by L. bul- garicus plus S. thermophilus showed sig- nificantly (P45) more antimutagenic ac- tivity than extracts prepared from milk fermented by S. thermophilus alone. Sol- vent (acetone vs. ethyl acetate) effect was not significant with 4-nitroquinoline-N- oxide as mutagen. However, in the case of 2-aminofluorene, acetone extracts showed sienificantly (P<.05) higher an- timutagenic activity. The results of this and related studies strongly indicate that antimutagenic compounds are produced in mills during fermentation by S. ther- mophilus and L. bulgan'cus.