Detoxification of aflatoxin B1 by manganese peroxidase from the white-rot fungus Phanerochaete sordida YK-624

Abstract Aflatoxin B1 (AFB1) is a potent mycotoxin with mutagenic, carcinogenic, teratogenic, hepatotoxic, and immunosuppressive properties. In order to develop a bioremediation system for AFB1-contaminated foods by white-rot fungi or ligninolytic enzymes, AFB1 was treated with manganese peroxidase (MnP) from the white-rot fungus Phanerochaete sordida YK-624. AFB1 was eliminated by MnP. The maximum elimination (86.0%) of AFB1 was observed after 48 h in a reaction mixture containing 5 nkat of MnP. The addition of Tween 80 enhanced AFB1 elimination. The elimination of AFB1 by MnP considerably reduced its mutagenic activity in an umu test, and the treatment of AFB1 by 20 nkat MnP reduced the mutagenic activity by 69.2%. 1H-NMR and HR-ESI-MS analysis suggested that AFB1 is first oxidized to AFB1-8,9-epoxide by MnP and then hydrolyzed to AFB1-8,9-dihydrodiol. This is the first report that MnP can effectively remove the mutagenic activity of AFB1 by converting it into AFB1-8,9-dihydrodiol.