Effect of ZnO-nanoparticles on Aspergillus flavus growth and aflatoxin accumulation both on a maize based medium and irradiated maize grains

Abstract

Maize (Zea mays L.) a main crop worldwide, is susceptible to fungal contamination specially byAspergillus flavus which produces aflatoxins (AFs) AFB1 and AFB2. These mycotoxins arecarcinogenic and can cause significant economic losses due to contamination in food and feedchains. Climate change, leading to more frequent droughts, exacerbates this issue by potentially increasing AFs contamination. Nanotechnology offers a promising option for controlling fungalpathogens and mycotoxins. Zinc oxide nanoparticles (ZnO-NPs) are particularly interesting to fortheir antifungal properties. This study was aimed to synthesize and characterized ZnO-NPs and to evaluate their effectiveness on reducing the A. flavus growth and AFs accumulation under in vitro(maize based medium) and in situ (irradiated maize grains) assays. ZnO-NPs were synthesized andcharacterized, showing stability and effective antifungal properties. In vitro, ZnO-NPs significantly reduced A. flavus growth rates by a 40-78% and AFB1 production by 93.6-100%. This also caused hyphal deformation and unusual bulges besides a decrease in the fungal conidiation. In situ, ZnO NPs caused reduction in fungal growth rates by ̴ 40% at 2 g/ kg. AFs reduction was observed in a wide range of percentages even at 99%, especially at low water activities. However, some treatments increased AFs production by 2-5-fold, due to probably not homogeneous nanoparticledistribution on grain surface, suggesting potential stress responses by the fungus. Overall, ZnONPs demonstrate strong potential for managing aflatoxin contamination in maize, though theirapplication must be carefully controlled to avoid unintended effects. Further field studies andenvironmental impact assessments are needed to optimize their use.