Degradation of aflatoxin B(1) by fungal laccase enzymes.

The enzymatic degradation of aflatoxin B(1) (AFB(1)) by white rot fungi through laccase production was investigated in different liquid media. A significant (P<0.0001) correlation was observed between laccase activity and AFB(1) degradation exhibited by representatives of Peniophora and Pleurotus ostreatus cultivated in minimal salts (MSM) (r=0.93) and mineral salts - malt extract (MSB-MEB) (r=0.77) liquid media. Peniophora sp. SCC0152 cultured in MSB-MEB liquid medium supplemented with veratryl alcohol and sugarcane bagasse showed high laccase activity (496U/L), as well as 40.45% AFB(1) degradation as monitored using high performance liquid chromatography. P.ostreatus St2-3 cultivated in MSM liquid medium supplemented with veratryl alcohol resulted in laccase activity of 416.39U/L and 35.90% degradation of AFB(1). Aflatoxin B(1) was significantly (P<0.0001) degraded when treated with pure laccase enzyme from Trametes versicolor (1U/ml, 87.34%) and recombinant laccase produced by Aspergillus niger D15-Lcc2#3 (118U/L, 55%). Aflatoxin B(1) degradation by laccase enzyme from T. versicolor and recombinant laccase enzyme produced by A. niger D15-Lcc2#3 coincided with significant (P<0.001) loss of mutagenicity of AFB(1), as evaluated in the Salmonella typhimurium mutagenicity assay. The degradation of AFB(1) by white rot fungi could be an important bio-control measure to reduce the level of this mycotoxin in food commodities.