Fumigation with dimethyl trisulfide to inhibit Aspergillus flavus growth, aflatoxin B1 production and virulence.

Abstract

Aspergillus flavus is a common saprophytic aerobic fungus in oil crops that poses a serious threat worldwide with the carcinogenic aflatoxin. Prevention of aflatoxin B1 contamination has great significance to ensure food safety and reduce the economic loss. The present work focuses on the antagonistic activity against A. flavus growth in peanuts by fumigation with dimethyl trisulfide. The results indicated that dimethyl trisulfide exhibits great antifungal activity against A. flavus. The conidial germination and mycelial growth of A. flavus were completely suppressed after exposure to 15 and 20 µl/L of dimethyl trisulfide, respectively. Numerous deformed conidia were found after exposure to dimethyl trisulfide at high concentration (≥ 20 µl/L). SEM observation demonstrated that dimethyl trisulfide induced severely shrinking mycelia of A. flavus. The results of OD-260 nm absorption and rhodamine-123 fluorescent staining indicated that cell membrane and mitochondria may be legitimate antifungal targets of dimethyl trisulfide. Dimethyl triethyl has a significant inhibitory effect on A. flavus infection in peanuts. In addition, dimethyl trisulfide could reduce production of aflatoxin B1 via downregulation of toxin synthesis and regulatory gene expression. Dimethyl trisulfide can be a tremendous potential agent for the biological control of A. flavus, and deepened our understanding of anti-fungal mechanisms of volatile organic compounds.