Degradation of Aflatoxin B1 and Zearalenone by Bacterial and Fungal Laccases in Presence of Structurally Defined Chemicals and Complex Natural Mediators

Abstract

Aflatoxin B₁ (AFB₁) and zearalenone (ZEN) exert deleterious effects to human and animal health. In this study, the ability of a CotA laccase from <i>Bacillus subtilis</i> (<i>Bs</i>CotA) to degrade these two mycotoxins was first investigated. Among the nine structurally defined chemical compounds, methyl syringate was the most efficient mediator assisting <i>Bs</i>CotA to degrade AFB₁ (98.0%) and ZEN (100.0%). <i>Bs</i>CotA could also use plant extracts, including the <i>Epimedium brevicornu</i>, <i>Cucumis sativus</i> L., <i>Lavandula angustifolia</i>, and <i>Schizonepeta tenuifolia</i> extracts to degrade AFB₁ and ZEN. Using hydra and BLYES as indicators, it was demonstrated that the degraded products of AFB₁ and ZEN using the laccase/mediator systems were detoxified. Finally, a laccase of fungal origin was also able to degrade AFB₁ and ZEN in the presence of the discovered mediators. The findings shed light on the possibility of using laccases and a mediator, particularly a natural plant-derived complex mediator, to simultaneously degrade AFB₁ and ZEN contaminants in food and feed.