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

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.