Abstract: In order to overcome the poor water solubility and instability of dihydromyricetin (DMY), a dihydromyricetin-silver ion (DMY-Ag+) nanoemulsion system was constructed, which could exert strong synergistic antibacterial activity. Its antibacterial mechanism was also investigated. The results showed that the minimum inhibitory concentration (MIC) of DMY against Staphylococcus aureus was 1.25 mg/mL. The DMY-Ag+ nanoemulsion was characterized as an oil-in-water emulsion. Its antibacterial activity was evaluated by the bacterial growth curve, the inhibition zone diameter and plate count. It was found that the nanoemulsion had an obvious synergistic effect when compared with DMY or Ag+ alone. The nanoemulsion could damage the integrity and selective permeability of the cell membrane, resulting in leakage of intracellular components, and partially or completely inhibit dehydrogenase activity in the cellular respiratory chain, thereby affecting normal energy supply and ultimately inhibiting or killing the bacterial cells. This study highlights the potential of the DMY-Ag+ nanoemulsion as a natural and highly effective bacteriostatic agent in the food industry.

Key words: dihydromyricetin, silver ion, nanoemulsion, Staphylococcus aureus, bacteriostatic mechanism