Study on antibacterial mechanism of electron beam radiation on Aspergillus flavus

Contamination with Aspergillus flavus, which produces carcinogenic metabolites, during the post-harvest storage of agricultural products seriously endangers human health and safety. In this study, the efficacy of short-term electron beam irradiation processing with high sterilization efficiency, no contamination and no additives was evaluated for the prevention and control of A. flavus. The effects of irradiation on Aspergillus growth were determined based on analyses of physical and chemical indexes, morphology, mycelial growth, spore germination rates, mycelial dry weights, and toxin-producing ability. The effects of irradiation on the cell membrane and cell wall of A. flavus were investigated based on assays of the chitin content, chitinase activity, protein concentration, and malondialdehyde content. Damage to the antioxidant system was determined by the hydrogen peroxide content, catalase activity, superoxide dismutase activity, superoxide anion radical scavenging activity and rates of 1,1-diphenyl-2-trinitrophenylhydrazine inhibition. The inhibitory effect of irradiation on peanut invasion by A. flavus was verified. After irradiation, the thallus morphology was destroyed, mycelial growth was inhibited, and the spore germination rate, mycelial dry weight, and toxin-producing ability of A. flavus were reduced. Chitinase activity and the malondialdehyde content increased, while the chitin and total protein contents decreased. Catalase activity, superoxide dismutase activity, superoxide anion radical scavenging activity, and the rate of 1,1-diphenyl-2-trinitrophenylhydrazine inhibition decreased, while the hydrogen peroxide content increased after irradiation. These findings suggested that electron beam irradiation can effectively inhibit the normal growth and toxin production of A. flavus. Irradiation increased cell membrane permeability and decreased the integrity of the cell wall. The antioxidant system was damaged to some extent. Compared with that in unirradiated A. flavus, high-dose electron beam irradiation effectively inhibited growth. As a means of postharvest control, electron beam irradiation may have wide applications in the agricultural industry.