Removal of Aflatoxin B1 by Edible Mushroom-Forming Fungi and Its Mechanism

Abstract

Aflatoxins (AFs) are biologically active toxic metabolites, which are produced by certain toxigenic Aspergillus sp. on agricultural crops. In this study, five edible mushroom-forming fungi were analyzed using high-performance liquid chromatography fluorescence detector (HPLC-FLD) for their ability to remove aflatoxin B-1 (AFB(1)), one of the most potent naturally occurring carcinogens known. Bjerkandera adusta and Auricularia auricular-judae showed the most significant AFB(1) removal activities (96.3% and 100%, respectively) among five strains after 14-day incubation. The cell lysate from B. adusta exhibited higher AFB(1) removal activity (35%) than the cell-free supernatant (13%) after 1-day incubation and the highest removal activity (80%) after 5-day incubation at 40 degrees C. In addition, AFB(1) analyses using whole cells, cell lysates, and cell debris from B. adusta showed that cell debris had the highest AFB(1) removal activity at 5th day (95%). Moreover, exopolysaccharides from B. adusta showed an increasing trend (24-48%) similar to whole cells and cell lysates after 5- day incubation. Our results strongly suggest that AFB(1) removal activity by whole cells was mainly due to AFB(1) binding onto cell debris during early incubation and partly due to binding onto cell lysates along with exopolysaccharides after saturation of AFB(1) binding process onto cell wall components.