Antimutagenicity and Binding of Lactic Acid Bacteria from a Chinese Cheese to Mutagenic Pyrolyzates

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Abstract
The microbiological characteristics of Nai Ge Da, a traditional cheese in China, was investigated. The lactic acid bacteria species were identified as Streptococcus cremoris, Streptococcus lactis ssp. diacetylactis, Streptococcus faecalis, and Leuconostoc paramesenteroides, Leuconostoc dextranicum, and Leuconostoc mesenteroides. Streptococcus cremoris, and Leuconostoc paramesenteroides were the dominant strains. The antimutagenicities and binding of strains of S. cremoris and S. lactic ssp. diacetylactis to mutagenic pyrolyzates was investigated. The lyophilized cells of strains showed the highest inhibitory effect on the 3-amino-1,4-dimethyl-[5H]pyrido[4,3-b] indol (Trp-P-1) and 3-amino-1-methyl-[5H]pyrido[4,3-b] indol (Trp-P-2), but many strains had no significant inhibition against 2-amino-6-methyldipyrido[1,2-a:3'',2''-d] imidazole (Glu-P-1). The Trp-P-1 and Trp-P-2 were effectively bound to all bacterial cells, but binding of Glu-P-1 to cells was not effective. Among the strains tested, S. cremoris C-25 not only indicated highest binding to Trp-P-1 and Trp-P-2, but also it had a 25.36% binding ability with Glu-P-1. When all strains were autoclaved for 15 min at 120.degree. C, binding ability to mutagens was reduced by 3 to 19%. The decrease of binding ability of S. cremoris C-25 was much less, being only 2%. After heating at 80.degree.C for 3 h, the binding ability of all strains to mutagenic pyrolyzates was not much different from those of parent viable cells.