USE OF FUNGAL LACCASES FOR AFLATOXIN REDUCTION IN MAIZE SUB-PRODUCTS

BOSSA, M. ; MONESTEROLO, N. E.; MONGE, M. P.; PALAZZINI, J. M.; PENA, G. A.; CHULZE, S. N; ALANIZ ZANON, M.; CHIOTTA, M. L.

Amberes

Congreso; The World Mycotoxin Forum®; 2023

Fungal contamination is a phytosanitary problem of concern in maize and by-products. Aspergillus section Flavi strains can generate important problems dueto contamination with aflatoxins (AFs). During the bioethanol production frommaize, AFs levels can increase up to three times in the final co-product (DDGSor WDGS), intended for animal feed. Mosto is the milled maize grains with theaddition of water and amylase enzymes that enter the fermentation stage. Onestrategy to reduce the mycotoxin contamination levels is the use ofmicroorganisms or enzymes able to metabolize, destroy or inactivate thosecompounds. Laccases are enzymes with biocatalytic capacity and widebiotechnological application, including food industry. Particularly, laccases fromfungi that cause white rot have been proposed for mycotoxin biotransformation.In the present work, the effectiveness of different fungal laccases in reducing AFslevels (AFB1, AFG1, AFB2 and AFG2) was evaluated under an in vitro assay.Laccase production by Phylum Basidiomycota strains was evaluated and 9 ofthem were selected to carry out in vitro decontamination tests. A concentration of1 µg/mL of AFB1 and AFG1, and 0.25 µg/mL of AFB2 and AFG2 were used atconcentrations of 5, 10, 15 and 20 U/mL of laccases contained in enzymeextracts, in addition to vanillic acid as redox mediator (1 and 10 mM). The strainTrametes sp. B7-IMICO-RC was able to degrade the 4 AFs at high levels underall the evaluated conditions. The highest degradation percentage was reached inpresence of 1 mM vanillic acid and 20 U/mL laccase (88, 99, 87 and 70%, forAFB1, AFG1, AFB2 and AFG2, respectively). An additional in vitro degradationassay of AFs was carried out using mosto as the substrate. The degradationpercentages observed under these same conditions were 26% for AFB1 and AFG2and 54% for AFG1. Currently, studies are being carried out in order to determinethe degradation products toxicity. These results would contribute to thedevelopment of an eco-friendly strategy to reduce mycotoxin contamination,ensuring food safety.