Abstract: Objective: To investigate the relationship between ciaH, eno, pykF genes and fluoride resistance through determining the differential expressions of ciaH, eno and pykF genes of fluoride-resistant Streptococcus mutans cultivated in fluoride environment.Methods: The cultured Streptococcus mutans and their fluoride-resistant strains were divided into UA (Streptococcus mutans subcultured in BHI without NaF), FR (fluoride-resistant Streptococcus mutans subcultured in BHI without NaF) and FFR (fluoride-resistant Streptococcus mutans subcultured in BHI containing 1 g·L^-1 NaF) groups. After 11 h (logarithmic phase) and 20 h (platform stage) cultivation, the expression levels of ciaH, eno and pykF mRNA were detected by RT-PCR method.Results: Compared with FR group, the expression levels of ciaH, eno and pykF mRNA in FFR group were increased both in the logarithmic phase and the platform stage(P<0.05 or P<0.01).Compared with UA group, the expression levels of eno and pykF mRNA in FR group were decreased both in the logarithmic phase and the platform stage(P<0.01), whereas the expression level of ciaH mRNA had no significant difference in the logarithmic phase (P>0.05), but it was increased in the platform stage (P<0.01).Conclusion: Fluoride can increase the expression levels of ciaH, eno and pykF genes in fluoride-resistant Streptococcus mutans, indicating that these genes are related to the production of fluoride resistance.

Key words: ciaH, pykF, eno, Streptococcus mutans, fluoride-resistant Streptococcus mutans, fluoride resistance