The High-Efficiency Degradation of Multiple Mycotoxins by Lac-W Laccase in the Presence of Mediators

Abstract

Mycotoxin cocontamination is a severe threat to health and economic security worldwide. The mycotoxins aflatoxin B1 (AFB1), zearalenone (ZEN), deoxynivalenol, T-2 toxin, fumonisin B1, and ochratoxin A are of particular concern due to their substantial toxicity. Lac-W is a laccase with the unique property of degrading these six mycotoxins in the absence of redox mediators. Nevertheless, their degradation rates are low. This work aims to improve the ability of Lac-W to degrade these six mycotoxins and to elucidate its detoxification mechanism. Including redox mediators increased the Lac-W degradation efficiency drastically, and completely degraded AFB1 and ZEN within one hour. Additionally, Lac-W-AS has good temperature, pH, and ions adaptability in ZEN degradation. Lac-W-AS reduced the ZEN toxicity because ZEN degradation products significantly restored the bioluminescence intensity of Vibrio fischeri. A Lac-W-AS-mediated oxidation product of ZEN was structurally characterized as 15-OH-ZEN by UHPLC-MS/MS. Linear sweep voltammetry showed that AS affected the potential of Lac-W and accelerated the oxidation of ZEN. Finally, the combination of mediators (acetosyringone and 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonate)) improved the degradation rate of mycotoxins. This work highlights that the combination of Lac-W with mediators serves as a good candidate for degrading multi-mycotoxin contaminants in food and feedstuff.

Keywords

• laccase mediator system
• detoxification
• zearalenone