Evidence suggesting that a soluble factor majorly contributes to the antimutagenic property of lactic acid bacteria against the heterocyclic amine, 2-amino-3,4-dimethyl-3H-imidazo[4,5-f]quinoline

We investigated the antimutagenicity of lactic acid bacteria (LAB) against 2 heterocyclic amines (HCAs), 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1) and 2-amino-3,4-dimethyl-3H-imidazo[4,5-f]quinoline (MeIQ), by the Ames assay, using Salmonella typhimurium TA98. The bacterial suspensions were prepared by storing viable LAB cells in phosphate-buffered saline at 4°C for 1 year. Compared with the pellet fraction, the supernatant fraction obtained after centrifugation of these suspensions significantly inhibited MeIQ mutagenicity. Thus, LAB were indicated to either possess or produce antimutagenic substance(s) against HCAs.