Aflatoxin B1 (AFB1) biodegradation by a lignolytic phenoloxidase of Trametes hirsuta

Aflatoxin B₁ (AFB₁) is a highly potent mycotoxin that poses a serious threat to human and animal health. This study investigated the biodegradation of AFB₁ by the supernatant of submerged cultured Trametes hirsuta, with a focus on identifying and characterizing the responsible enzyme(s). The extracellular enzymes of the white-rot mushroom were extracted from the supernatant and pre-separated using anion exchange fast protein liquid chromatography (FPLC). To pinpoint the specific enzyme, the eluted protein fractions exhibiting the highest degradation activity were subjected to detailed biochemical and proteomic analyses. A second purification step, ultrafiltration, yielded an electrophoretically pure enzyme. Sequencing of tryptic peptides using a nano-LC system coupled to a qQTOF mass spectrometer identified the enzyme as a lignolytic phenoloxidase. The enzyme exhibited a molecular mass of 55.6 kDa and achieved an impressive AFB₁ degradation rate of 77.9% under optimized experimental conditions. This is the first fungal lignolytic phenoloxidase capable of aflatoxin degradation without requiring hydrogen peroxide as a cofactor, highlighting its unique catalytic mechanism. It may be used in mycotoxin remediation strategies, such as treating the surfaces of contaminated fruits, vegetables, and nuts.