Organic acids suppress aflatoxin production via lowering expression of aflatoxin biosynthesis-related genes in Aspergillus flavus

Aflatoxins are naturally occurring carcinogens. Humans and animals, such as turkeys, are highly susceptible to aflatoxin-induced diseases. In this study, we investigated the inhibitory effects of 5 food additives on the growth and aflatoxin production in Aspergillus flavus ATCC 22546. Propionic acid completely inhibited fungal growth at a concentration of 0.5%. Furthermore, no fungal growth was observed when the growth medium was treated with 0.05% benzoic acid, 0.1% sorbic acid, 0.5% acetic acid, or 0.5% butyric acid. In comparison to propionic acid, other food additives showed weak antifungal activities. Propionic acid, butyric acid, benzoic acid, and sorbic acid also exhibited potent antiaflatoxigenic activities at a concentration of 0.1%. However, addition of 0.1% acetic acid did not inhibit aflatoxin production. At a concentration of 0.05%, propionic acid lost its antiaflatoxigenic activity, whereas at the same concentration, benzoic acid, butyric acid, and sorbic acid showed potent antiaflatoxigenic activities with a 95% inhibition of aflatoxin production. Benzoic acid drastically inhibited the expression of genes related to aflatoxin biosynthesis, whereas sorbic acid only inhibited the expression of a transcription gene, yab. Collectively, our results suggest that benzoic acid is promising alternative to propionic acid as food preservatives.