Fungal Laccases and Fumonisin Decontamination in Co-Products of Bioethanol from Maize.

Maize ( Zea mays L.) may be infected by Fusarium verticillioides and F. proliferatum , and consequently contaminated with fumonisins (FBs), as well as the co-products of bioethanol intended for animal feed. Laccase enzymes have a wide industrial application such as mycotoxin degradation. The aims were to isolate and identify fungal laccase-producing strains, to evaluate laccase production, to determine the enzymatic stability under fermentation conditions, and to analyse the effectiveness in vitro of enzymatic extracts (EEs) containing laccases in degrading FB 1 . Strains belonging to Funalia trogii , Phellinus tuberculosus , Pleurotus ostreatus , Pycnoporus sanguineus and Trametes gallica species showed laccase activity. Different isoforms of laccases were detected depending on the evaluated species. For the FB 1 decontamination assays, four enzymatic activities (5, 10, 15 and 20 U/mL) were tested, in the absence and presence of vanillic acid (VA) and 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) as redox mediators (1 and 10 mM). Trametes gallica B4-IMICO-RC EE was the most effective strain in buffer, achieving a 60% of FB 1 reduction. Laccases included in EEs remained stable at different alcoholic degrees in maize steep liquor (MSL), but no significant FB 1 reduction was observed under the conditions evaluated using MSL. This study demonstrate that although laccases could be good candidates for the development of a strategy to reduce FB 1 , further studies are necessary to optimise this process in MSL.