Antifungal and Antiaflatoxigenic Potential of Lactic Acid Bacteria Against Aspergillus flavus and Aspergillus parasiticus for Wheat Grain Protection

Abstract

Aflatoxin contamination of cereal grains represents a serious food safety concern due to the toxic and carcinogenic properties of aflatoxins produced mainly by Aspergillus species. The present study aimed to evaluate the antifungal and antiaflatoxigenic potential of lactic acid bacteria (LAB) cell-free supernatants as a natural approach for controlling aflatoxin-producing fungi in wheat grains. A total of fifty fungal isolates recovered from agricultural samples were screened for their aflatoxigenic potential using phenotypic and molecular approaches. The toxigenic isolates were identified as Aspergillus flavus (AF) and Aspergillus parasiticus (AP), and their aflatoxigenic potential was confirmed by PCR amplification of aflatoxin biosynthesis-related genes (nor-1 and aflR). The antifungal activity of selected LAB strains was evaluated against the identified Aspergillus isolates using the agar diffusion method. The obtained results demonstrated that LAB cell-free supernatants exhibited significant antifungal activity, with variations among strains. Among the tested LAB strains, Lactobacillus plantarum P3 and Lactobacillus acidophilus ATCC 20552 showed the highest inhibitory activity against both fungal species. Furthermore, LAB treatments significantly reduced fungal-induced wheat grain damage and decreased aflatoxin accumulation during storage. Application of 100% LAB supernatants resulted in a remarkable reduction in total aflatoxins, reaching more than 99% reduction compared with untreated controls. The inhibitory effect decreased with increasing dilution of the supernatants, indicating a concentration-dependent antifungal and antiaflatoxigenic activity. The findings demonstrate that LAB-derived metabolites can effectively suppress the growth of aflatoxin-producing Aspergillus species and limit aflatoxin biosynthesis. Therefore, LAB cell-free supernatants represent a promising biological control strategy for improving cereal safety and reducing mycotoxin contamination in food systems.