SUPPRESSIVE EFFECTS OF THE METHANOL EXTRACTS FROM SOYBEAN PRODUCTS ONSOS RESPONSE OF SALMONELLA-TYPHIMURIUM INDUCED BY MUTAGENS AND THEIR CONTENTS OF ISOFLAVONES

The suppressive effects on SOS response of Salmonella typhimurium TA 1 535/pSK 1002 induced by MNNG and Trp-P-1 of the methanol extracts prep ared from soybeans and soy products were investigated. The content of isoflavones in the extract was also determined. The extracts of soybea n and soymilk scarcely suppressed SOS response by mutagens. The suppre ssion by the extracts of fermented product was stronger than that by t he unfermented products. However, the percentage suppression in the ex tracts of natto and soy sauce was similar to that in the unfermented p roducts. The extracts of tempeh and mise having strong suppression con tained much daidzein and genistein. On the other hand, the extracts of unfermented product and such fermented product as natto and soy sauce having weak suppression contained much isoflavone glycoside. The perc entage suppression of the extracts from soymilks fermented by a strain of Lactobacillus bulgaricus or Streptococcus thermophilus was lower t han that by a strain of Bifidobacterium longum or a mixture of three s trains.