Effective and food-grade detoxification of multiple mycotoxins using yeast expressed manganese peroxidases

Mycotoxins in grains pose severe threat to human and animal health. Previous studies showed that manganese peroxidases had degradation capability for various mycotoxins. In this work, to effectively detoxify aflatoxin B1 (AFB1), zearalenone (ZEN) and deoxynivalenol (DON), the manganese peroxidases PhcMnp and IrlMnp from Phanerochaete chrysosporium and Irpex lacteus were successfully expressed in Pichia pastoris in a food-grade manner, and were used for degradation tests with the three mycotoxins. The fermentation supernatants containing PhcMnp achieved degradation ratios of 76.56%, 70.78% and 48.93% for AFB1, ZEN and DON respectively, while that containing IrlMnp achieved degradation ratios of 46.72%, 45.13% and 41.64% correspondingly. The inducible expression conditions for the enzymes and the reaction parameters for the mycotoxin degradations were both optimized. Furthermore, the fermentation supernatants of strain Pichia pastoris GS115 (pPIC9K-Phcmnp) were used for mycotoxin degradations in contaminated peanut samples (pH 4.5) at 40 °C for 10 h, resulting in apparent detoxification effects. The residual concentrations of AFB1, ZEN and DON in peanut samples after degradations were 9.42, 127.68 and 636.71 μg/kg respectively, all of which remained below the legal limits. Results in this study demonstrated that the enzymes PhcMnp and IrlMnp have potentials in mycotoxins detoxification in feed industry.