Identification of an M20 Family Metallopeptidase with Amidohydrolase Activity from Alcaligenes faecalis HNGD-HTN06 and Simultaneous Degradation of Ochratoxin A, Aflatoxin B1, and Zearalenone

Ochratoxin A (OTA) is a ubiquitous mycotoxin, highlighting the need for efficient strategies to eliminate it. In this study, an effective OTA-degrading bacterium, Alcaligenes faecalis strain HNGD-HTN06, was isolated from soil. OTA hydrolase was obtained through the integration of genome identification and heterologous expression. An M20 family metallopeptidase with amidohydrolase activity (SoAH) was identified and had the potential to degrade 98% of OTA within 20 min by cleaving its amide bond, producing ochratoxin α (OTα). In vivo toxicity assays in zebrafish revealed a significantly lower toxicity for the degradation products compared with the parent compound. Meanwhile, at pH 8, the degradation rate of aflatoxin B₁ (AFB₁) by SoAH was 93.39% at 40 °C, and the zearalenone (ZEN) degradation rate achieved 94.38% at 60 °C. The degradation products of AFB₁ and ZEN by SoAH were identified as AFQ₁/epi-AFQ₁/AFB₁-diol and 13-OH-ZEN/15-OH-ZEN, respectively. The capability of SoAH to degrade multiple mycotoxins could offer potential applicability in the food or feed industry.