Inhibitory effects of K12 on formation of cariogenic biofilm.

BACGROUND/PURPOSE: () K12 is known to be a probiotic bacterium. The purpose of this study was to investigate anti-cariogenic effects of K12 on cariogenic biofilm.

MATERIALS AND METHODS

K12 was cultured in M17 broth. The antimicrobial activity of spent culture medium (SCM) against was investigated. K12 was co-cultivated with using a membrane insert. When the biofilm was formed using salivary bacteria and , the K12 was inoculated every day. The biomass of biofilm was investigated by a confocal laser scanning microscope. Also, bacterial DNA from the biofilm was extracted, and then bacteria proportion was analyzed by quantitative PCR using specific primers. The expression of genes of in the biofilm with or without K12 was analyzed by RT-PCR.

RESULTS

The SCM of K12 inhibited the growth of . Also, K12 reduced growth in co-cultivation. The formation of cariogenic biofilm was reduced by adding K12, and the count of in the biofilm was also decreased in the presence of K12. B, C, and D expression of in the biofilm was reduced in the presence of K12.

CONCLUSION

K12 may inhibit the formation of cariogenic biofilm by interrupting the growth and glucosyltransferase production of .