Insight into the synergistic antibacterial effect of Nisin and Chinese chive seed extract against Staphylococcus aureus and their application in pasteurized milk

Food Microbiol. 2025 Oct;131:104816. doi: 10.1016/j.fm.2025.104816. Epub 2025 May 14.

ABSTRACT

Nisin has been considered as a food preservative against Staphylococcus aureus, a significant foodborne pathogen that poses a threat to human health. However, the effectiveness of Nisin is also affected due to its instability. In virtue of this, the synergistic antibacterial activity of Nisin combined with Chinese chive seed extract (CSE) against S. aureus was evaluated. Checkerboard assays indicated that Nisin and CSE showed a synergistic effect on S. aureus ATCC29213 with fractional inhibitory concentration indices = 0.25. Time-kill assays revealed that the combined treatment resulted in a significant reduction in the number of S. aureus than either Nisin or CSE treatment alone (P < 0.05). Scanning electron microscopy suggested the depression of the cell surface following treatment with combination with Nisin and CSE. The positive effect of CSE on Nisin activity was further confirmed by DNA and protein leakage, flow cytometry as well as confocal laser scanning microscopy. The combination of Nisin and CSE significantly changed the adhesion, quorum sensing and global regulation genes expression of S. aureus compared with the Nisin or CSE treatment alone by real-time fluorescence quantitative PCR (P < 0.05). Nisin combined with CSE has a more effective antibacterial effect in pasteurized milk than either Nisin or CSE alone during 8 d at 25 °C and 4 °C. These results revealed that the combination of Nisin and CSE could serve as an effective natural preservative to control S. aureus in dairy products.

PMID:40484536 | DOI:10.1016/j.fm.2025.104816