Maize (Zea mays L.) is an important crop in Argentina. Aspergillus section Flavi can infect this crop at the pre-harvest stage, and the harvested grains can be contaminated with aflatoxins (AFs). During the production of bioethanol from maize, AF levels can increase up to three times in the final co-products, known as, dry and wet distiller’s grain with solubles (DDGS and WDGS), intended for animal feed. Fungal enzymes like laccases can be a useful tool for reducing AF contamination in the co-products obtained from this process. The aim of the present study was to evaluate the ability of laccase enzymes included in enzymatic extracts (EE) produced by different species in the Basidiomycota phylum to reduce AF (AFB₁ and AFB₂) accumulation under the conditions of in vitro assays. Four laccase activities (5, 10, 15, and 20 U/mL) exerted by nine isolates were evaluated in the absence and presence of vanillic acid (VA), serving as a laccase redox mediator for the degradation of total AFs. The enzymatic stability in maize steep liquor (MSL) was confirmed after a 60 h incubation period. The most effective EE in terms of reducing AF content in the buffer was selected for an additional assay carried out under the same conditions using maize steep liquor obtained after the saccharification stage during the bioethanol production process. The highest degradation percentages were observed at 20 U/mL of laccase enzymatic activity and 1 mM of VA, corresponding to 26% for AFB₁ and 26.6% for AFB_2. The present study provides valuable data for the development of an efficient tool based on fungal laccases for preventing AF accumulation in the co-products of bioethanol produced from maize used for animal feed.

Aflatoxin contamination of maize by Aspergillus section Flavi constitutes a major health and economic concern. While biological control using non-toxigenic strains has proven effective, the increasing global food demand underscores the need for alternative carrier materials to replace seeds and grains. The aims of the present study were (1) to develop an innovative macroporous starch polymer in which the biocontrol agent can grow and be transported to fields where the bioformulate is applied, and (2) to evaluate the effectiveness of this new formulate in reducing AF contamination in maize kernels in field trials, in comparison with the traditional formulate based on long-grain rice as a substrate. Several methods and different starch sources were tested, and the formulation consisting of 10% maize starch, 0.5% citric acid, 3% sucrose, 0.3% urea, and distilled water was the most effective. Furthermore, this bioformulate demonstrated a performance comparable to that of the traditional long-grain rice-based formulation, reducing AF accumulation by up to 81% in maize kernels under field conditions. The implementation of this macroporous starch polymer-based formulation, in combination with the biological control agent A. flavus AFCHG2, would not only reduce aflatoxin contamination in maize kernels but also minimise the use of food-grade seeds and grains for industrial purposes, thereby preserving their availability for human and animal nutrition. Consequently, this development could enhance the availability of these substrates for food and feed use, thereby contributing to improved safety and food security.

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 FB₁. 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 FB₁ 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 FB₁ reduction. Laccases included in EEs remained stable at different alcoholic degrees in maize steep liquor (MSL), but no significant FB₁ 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 FB₁, further studies are necessary to optimise this process in MSL.