The Inhibition Effect and Mechanism of Nano Magnesium Peroxide Against Spoilage Fungi Emerging in Hami Melon

Hot summer is the primary harvest season for Hami melon; meanwhile, Hami melon has a vigorous respiration and transpiration, and reticular stripes, which are easily attached by pathogens; these conditions have aggravated the decay of Hami melon. Therefore, the present study aims to clarify the dominant spoilage fungi on Hami melon to evaluate the inhibitory effect of nano magnesium peroxide (MgO 2 NPs) on the dominant spoilage fungi, to find the appropriate concentration of MgO 2 NPs for controlling disease, and to explore the inhibitory mechanism of MgO 2 NPs on the dominant fungi. The results showed (1) Alternaria alternata is the dominant spoilage fungus on Hami melon. (2) MgO 2 NPs had significant inhibitory effects on Alternaria alternata on both medium and Hami melons. The MgO 2 NP concentration of 4 g/L with a fungus inhibition rate of 80% was selected as the fungus inhibition concentration of Hami melon. (3) About 4 g/L MgO 2 NPs was added to the spore solution of Alternaria alternata. Spore shrinkage deformation was observed by microscope. Propidium iodide (PI) infiltration experiments verified that MgO 2 NPs enhanced the permeability of spore membranes. The alkaline phosphatase (AKP) activity, conductivity, and protein concentration of the spore solution were analyzed, which revealed the destructive effects of MgO 2 NPs on fungal spores. MgO 2 NPs could successively act on the spore wall and membrane for several hours and eventually lead to spore rupture and death so as to achieve the antimicrobial effect. MgO 2 NPs provides powerful support for developing a more appropriate storage method for Hami melon.