Efficient degradation of aflatoxin B1 by Arthrobacter citreus Soilh02: Characterization, degradation products, and detoxification mechanism.

Abstract

Aflatoxin B1 (AFB1) is a highly toxic mycotoxin prevalent in food and feed that poses a grave threat to human and animal health. In this study, an AFB1- degrading strain of Arthrobacter citreus, designated Soilh02, was isolated. Under optimal conditions (37 °C, pH 8.0, 72 h), the presence of Cu2+ significantly enhanced AFB1 degradation, achieving a maximum degradation rate of 93.96%. Ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-QTOF) identified two novel degradation products with molecular formulas C18H 20O7 and C16H14O6, and proposed plausible structures for these compounds based on accurate mass data and fragmentation pathways. Subsequently, ultrafiltration, DE52 anion-exchange chromatography, activity assays, and SDS-PAGE were used to isolate and purify the extracellular proteins responsible for AFB1 degradation. LC-MS/MS and molecular docking analyses suggested that oxidoreductase RE1 may participate in AFB1 degradation, as its activity was markedly suppressed by inhibitors. RE1 bound AFB1 with a binding energy of -8.511 kcal/mol and was capable of degrading its difuran, lactone, and cyclopentenone ring via Lys-210, Arg-422, and Phe-427. Overall, this study provides a high-quality microbial resource and a theoretical basis for developing efficient and eco-friendly AFB1 biodegradation strategies. These findings offer significant potential for enhancing food and feed safety and promoting sustainable agricultural practice.