Antifungal properties of recombinant Puroindoline B protein against aflatoxigenic Aspergillus flavus.

Aspergillus flavus contamination is of great concern to food safety. Our previous studies demonstrated that recombinant Puroindoline B protein (rPINB) has an inhibitory effect on A. flavus mycelium development. However, fungal contamination often begins with spore germination within food shelf life. Here, rPINB was evaluated for its antifungal properties against A. flavus spores in vivo and in vitro. The results showed that rPINB could inhibit spore formation and aflatoxin B1 of A. flavus on maize. In vitro analysis revealed its dose-dependent antifungal effect on spore germination and germ tube growth of A. flavus. Scanning electron microscopy revealed that rPINB exposure altered spore morphology, indicating it damaged the cell wall. Transmission electron microscopy and the inhibition of ergosterol synthesis further revealed that rPINB exposure significantly damaged the cell membrane. The mitochondrial membrane potential decreased, and DNA fragments were scattered in the cytoplasm as detected using 5,5′,6,6′-tetrachloro-1,1′,3,3′-tetraethylbenzimidazolocarbocyanine iodide and 4′,6-diamidino-2-phenylindole staining. The direct antifungal activity of rPINB observed both in vivo and in vitro suggests that rPINB may be used to prevent fungal contamination of stored foods and agricultural products in the future. • rPINB can inhibit A. flavus spore formation and aflatoxin B production on maize. • The antifungal effect of rPINB on A. flavus is dose-dependent. • rPINB exposure affected the integrity of A. flavus cell wall and cell membrane. • rPINB may inhibit A. flavus development by destroying its cell wall and cell membrane structures. • rPINB may prevent fungal contamination of food and agricultural products. [ABSTRACT FROM AUTHOR]