Degradation and detoxification of aflatoxin B1 by two peroxidase enzymes from Irpex lacteus F17.

Abstract

Aflatoxin B1 (AFB1), the most toxic mycotoxin produced by some Aspergillus species, is commonly found in agricultural products, especially grains, and poultry feeds. Enzymic degradation is considered to be the most promising detoxification method, because it is efficient, safe and causes minimal damage to the nutritional quality of treated foods. In this study, a recombinant manganese peroxidase (Il-MnP1) and a recombinant dye-decolorizing peroxidase (Il-DyP4) from Irpex lacteus F17 were used to degrade AFB1, either individually or in combination. The degree of degradation of AFB1 by the combined enzymes of Il-MnP1 + Il-DyP4 was higher than that of either enzyme acting alone. The half-life of AFB1 degradation by the combined enzymes was lower than that of either enzyme alone. Further analysis of the degradation products indicated that the use of the combination of Il-MnP1 + Il-DyP4 to degrade AFB1 resulted in a greater number of metabolites, including five new degradation products with the chemical formulas, C₁₆H₁₀O₈, C₁₅H₁₀O₅, C₁₅H₁₀O₆, C₁₆H₁₀O₇, and C₁₆H₈O₇. The system of Il-MnP1 + Il-DyP4 contained multiple enzyme activities that could act on different toxic sites of AFB1, thereby producing metabolites with lower toxicity and carcinogenicity, which was consistent with the results of the Ames test. These findings suggest that using the combined enzymes to convert AFB1 into non-toxic products is a good strategy for detoxifying contaminated foods and feeds.