MYCOTOXIN DEGRADATION BY LACCASE ENZYMES FROM PLEUROTUS SPP

Mycotoxin occurrence in staple food commodities represents a great concern worldwide. These fungal metabolites constitute an important food safety hazard due to their demonstrated toxic, carcinogenic, teratogenic and mutagenic activity towards humans and animals (International Agency on Research on Cancer, 2012). Mycotoxin contamination greatly affects global economy and international trade, accounting for billions of dollars lost every year all along the food and feed supply chains (Wu, 2015). The development of new methods for mycotoxin reduction is a crucial and concrete struggle, especially with regards to food and feed supply chains. With this aim, we evaluated the degrading activity of two pure laccase enzymes from Pleurotus spp towards aflatoxin B1 (AFB1), aflatoxin M1 (AFM1) and zearalenone. (ZEA) Laccases were produced and purified to homogeneity and tested in in vitro degradation assays, performed in buffer solution (sodium acetate pH5 1mM). After 72h of static incubation at 25°C, chemical analyses revealed that both laccase enzymes were able to degrade AFB1 (up to 90%), AFM1 (up to 100%) and ZEA (up to 100%). Laccase degrading activity was also tested in real matrices, such as skimmed UHT milk artificially contaminated with AFM1 and maize flour naturally contaminated with zearalenone. AFM1 was completely degraded within 72h, while ZEA was reduced by 40% within 5 days of incubation at 25°C. The green feature, effectiveness and multi mycotoxin degrading capability of laccase enzymes are the key attributes of a potential biotransforming agent. These results opened new perspective for laccase application in the food and feed supply chains.