Genome-Guided Discovery of Enterobacter Multicopper Oxidases Enabling Enzymatic Detoxification of Aflatoxin B1.

Abstract

Aflatoxin B1 is a potent Group I carcinogen that contaminates food and feed, necessitating efficient detoxification strategies. This study isolated a novel bacterial strain, Enterobacter sp. HNGD-822 from soil, which efficiently degrades AFB1. Genome analysis identified two novel multicopper oxidase (laccase) genes, EbMCO1 and EbMCO2. The recombinant enzymes were heterologously expressed, exhibiting optimal activity at 50 °C and pH 7.0, with strict Cu2+ dependence. Within 12 h, EbMCO1 degraded over 99% of AFB1, while EbMCO2 also showed high activity under the same conditions. Both enzymes primarily converted AFB1 into AFQ1 and epi-AFQ1, products that exhibited significantly reduced hepatotoxicity, developmental toxicity, and oxidative stress in transgenic zebrafish. Applied to artificially contaminated peanut meal matrices, EbMCO1 and EbMCO2 achieved degradation efficiencies of 89.35% and 82.66%, respectively, without altering nutritional quality. This work presents novel laccases with promising potential for the biocontrol of AFB1 in the feed and food industries.