Enzymatic transformation of aflatoxin B by Rh_DypB peroxidase and characterization of the reaction products.

In some environments, a number of crops, notably maize and nuts can be contaminated by aflatoxin B and related compounds resulting from the growth of aflatoxin-producing Aspergilli. Fungal peroxidases have been shown to degrade a number of mycotoxins, including aflatoxin B (AFB). Therefore, the purpose of this study was to investigate the in vitro enzymatic degradation AFB by a recombinant type B dye decolorizing peroxidase (Rh_DypB). Analysis of the reaction products by HPLC-MS analysis showed that under optimized conditions AFB was efficiently transformed by Rh_DypB, reaching a maximum of 96% conversion after 4 days of reaction at 25 °C. Based on high resolution mass spectrometry analysis, AFB was demonstrated to be quantitatively converted to AFQ, a compound with a significantly lower toxicity. A number of low molecular mass compounds were also present in the final reaction mixture in small quantities. The results presented in this study are promising for a possible application of the enzyme Rh_DypB for aflatoxin reduction in feed.