Antibacterial activity of zinc oxide nanoparticles against Shewanella putrefaciens and its application in preservation of large yellow croaker (Pseudosciaena crocea).

Specific spoilage organisms (SSOs) are the key factors affecting the deterioration of large yellow croaker. This study investigated the antibacterial activity and mechanism of Zinc oxide nanoparticles (ZnO-NPs) against Shewanella putrefaciens. The effects of different concentrations of ZnO-NPs (0.5, 1, 2 mg/mL) combined with seawater slurry ice preservation on storage quality and microbial community of large yellow croaker were further investigated. The results showed that ZnO-NPs had a strong antibacterial effect on Shewanella putrefaciens, which destroyed the integrity of the cell membrane, resulting in nucleic acid leakage and increased electrical conductivity. In addition, ZnO-NPs could effectively inhibit the proliferation of microorganisms, slow down the rate of lipid oxidation, delay the rise of pH value and total volatile basic nitrogen, and maintain the color of fish. Among them, 2 mg/mL ZnO-NPs treatment showed the best preservation effect on large yellow croaker. High-throughput sequencing results showed that Pseudoalteromonas and Shewanella became the dominant spoilage bacteria with the extension of storage time. ZnO-NPs significantly reduced the relative abundance of dominant spoilage bacteria and changed the microbial composition of fish. Inhibition of the growth of SSOs was important for delaying spoilage and prolonging the shelf-life of large yellow croaker. Therefore, ZnO-NPs combined with seawater slurry ice preservation could be used as a new storage method, which provides a new idea for food quality and safety control.