Characterization and mechanism of simultaneous degradation of aflatoxin B1 and zearalenone by an edible fungus of Agrocybe cylindracea GC-Ac2

Abstract

Contamination with multiple mycotoxins is a major issue for global food safety and trade. This study focused on the degradation of aflatoxin B₁ (AFB₁) and zearalenone (ZEN) by 8 types of edible fungi belonging to 6 species, inclulding <i>Agaricus bisporus</i>, <i>Agrocybe cylindracea</i>, <i>Cyclocybe cylindracea</i>, <i>Cyclocybe aegerita</i>, <i>Hypsizygus marmoreus</i> and <i>Lentinula edodes.</i> Among these fungi, <i>Agrocybe cylindracea</i> strain GC-Ac2 was shown to be the most efficient in the degradation of AFB₁ and ZEN. Under optimal degradation conditions (pH 6.0 and 37.4°C for 37.9 h), the degradation rate of both AFB₁ and ZEN reached over 96%. Through the analysis of functional detoxification components, it was found that the removal of AFB₁ and ZEN was primarily degraded by the culture supernatant of the fungus. The culture supernatant exhibited a maximum manganese peroxidase (MnP) activity of 2.37 U/mL. Interestingly, <i>Agrocybe cylindracea</i> strain GC-Ac2 also showed the capability to degrade other mycotoxins in laboratory-scale mushroom substrates, including 15A-deoxynivalenol, fumonisin B₁, B₂, B₃, T-2 toxin, ochratoxin A, and sterigmatocystin. The mechanism of degradation of these mycotoxins was speculated to be catalyzed by a complex enzyme system, which include MnP and other ligninolytic enzymes. It is worth noting that <i>Agrocybe cylindracea</i> can degrade multiple mycotoxins and produce MnP, which is a novel and significant discovery. These results suggest that this candidate strain and its enzyme system are expected to become valuable biomaterials for the simultaneous degradation of multiple mycotoxins.