Selective in vitro binding of dietary mutagens, individually or in combination, by lactic acid bacteria

Specific strains of lactic acid bacteria possessing antimutagenic properties are suggested to remove mutagenic contaminants of foods through binding and an investigation of their substrate specificity is required. The ability of Lactobacillus rhamnosus strains GG and LC-705 in viable and non-viable (heat- and acid-treated) forms to remove both dietary mutagens and other aromatic dietary substrates from solution was studied using HPLC. Overall, removal increased in the order: caffeine = vitamin B-12 = folic acid < ochratoxin A< aflatoxin B-1 = PhIP (2-amino-1-methyl-6-phenyl-imidazo[ 4,5-b] pyridine) <Trp-P-1 (3-amino-1, 4-dimethyl-5H-pyrido[ 4,3-b] indole) (p <0.05). Aflatoxin B-1, Trp-P-1 and PhIP were removed in high amounts (77-95%) and ochratoxin A was removed in moderate amounts (36-76%). By contrast, only minimal amounts of caffeine, vitamin B-12 and folic acid were removed (9-28%). The significant removal of selected mutagens, but not other substrates, suggests these strains may be useful for dietary detoxification. Since exposure to multiple mutagens is likely, the removal of aflatoxin B-1 and Trp-P-1 from a mixture of these substrates was also investigated. Removal of AFB(1) significantly increased (p <0.05) in the presence of Trp-P-1, while removal of Trp-P-1 significantly decreased (p <0.05) in the presence of AFB(1). Overall, no significant differences in removal were found between bacterial strains or between viable, heat- and acid-treated bacteria.