Characterization of zinc oxide nanoparticles-epoxy resin composite and its antibacterial effects on spoilage bacteria derived from silvery pomfret (Pampus argenteus)

Epoxy resin was conjugated with zinc oxide nanoparticles (ZnO NPs) to prepare antibacterial zinc oxide-epoxy resin (ZnO-ER) composite. The property of ZnO-ER was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and SEM-energy dispersive X-ray spectroscopy (SEM-EDS) assays. Results showed the presence of ZnO NPs on the surface and cross-sections of ZnO-ER composite. The average thickness of ZnO-ER was 392.38 mu m. The strong antibacterial effect of ZnO-ER on the test bacterial mixture derived from spoiled silvery pomfret (Pampus argenteus) was observed using SEM assay. After addition of ZnO-ER for 6 h in the bacterial mixture, cellular membrane integrities of most bacteria were destroyed. High-throughput 16S ribosomal RNA gene sequencing revealed the decreases of both community richness and diversity in the ZnO-ER treated bacterial mixture. As for relative abundances, significant decreases were detected in the phyla Bacteroidetes and Firmicute, while dramatic increase of the phylum Proteobacteria was observed after ZnO-ER treatment. The family of Enterobacteriaceae was predominant in the ZnO-ER treatment. The genera of Providencia and Yersinia showed dramatically high relative abundances. However, the abundances of some specific genera such as Aeromonas and Shewanell, which are related to human infections or food spoilage, were decreased to 0.00% after addition of ZnO-ER for 6 h. When the incubation time of ZnO-ER with the bacterial mixture was prolonged to 24 h, bacteria colony was hardly detected to a negligible level. The results suggest the potential application of ZnO-ER in food packaging to inhibit spoilage bacteria derived from aquatic organisms.