Abstract: Objective: To develop a mouthwash containing the bacteriophage lysin LysP53 and evaluate its bactericidal activity, cytotoxicity, and stability in vitro. Methods: LysP53 was cloned, expressed, and purified in vitro and prepared into mouthwash. The bactericidal effect of LysP53 was evaluated by bactericidal activity assay, crystal violet staining test, and scanning electron microscopy. Its safety was assessed in vitro by CCK-8. Stability was evaluated by the effect on LysP53 mouthwash bactericidal activity at different temperatures. Results: 8 μmol/L LysP53 mouthwash had bactericidal effect on the main cariogenic bacteria Streptococcus mutans, Streptococcus sobrinus, and Actinomyces naeslundii (P＜0.05), but had poor antibacterial activity against the common commensal bacteria Streptococcus oralis, Streptococcus mitis, and Streptococcus sanguinis (P＞0.05). Application of LysP53 mouthwash in established biofilms disintegrated the biofilm structure and effectively reduced the number of viable bacteria (P＜0.05). CCK-8 showed no statistical difference in cell viability between the groups (P＞0.05). LysP53 mouthwash showed no difference in bactericidal efficiency after 1 hour of storage at 4, 37, 43, 60, and 95 ℃, and still showed excellent bactericidal activity. Conclusion: LysP53 mouthwash has good antibacterial activity, safety, and stability. It has great potential in preventing dental caries for routine oral hygiene measures.

Key words: dental caries, Streptococcus mutans, bacteriophage lysin, mouthwashes