Dose-Dependent Inhibitory Effect of Probiotic Lactobacillus plantarum on Streptococcus mutans - Candida albicans Cross-Kingdom Microorganisms.

Dental caries is one of the most common chronic diseases worldwide. and are two major pathogens associated with dental caries. Several recent studies revealed that inhibits and in biofilms and in a rodent model of dental caries. The aim of this study was to investigate the dose-dependent effect of against and in a planktonic model that simulated a high-caries-risk clinical condition. Mono-, dual-, and multi-species models were utilized, with five doses of (ranging from 1.0 × 10 to 1.0 × 10 CFU/mL). Real-time PCR was used to assess the expression of the virulence genes of and and the genes of . Student's -tests and one-way ANOVA, followed by post hoc tests, were employed to compare the cell viability and gene expression among groups. A dose-dependent inhibition on and was observed with increased dosages of . at 10 CFU/mL demonstrated the highest antibacterial and antifungal inhibitory effect in the dual- and multi-species models. Specifically, at 20 h, the growth of and was suppressed by 1.5 and 5 logs, respectively ( < 0.05). The antifungal and antibacterial effects were attenuated in lower doses of (10-10 CFU/mL). The expression of and genes and and genes were significantly downregulated with an added 10 CFU/mL of ( < 0.05). The addition of 10 CFU/mL further inhibited the hyphae or pseudohyphae formation of . In summary, demonstrated dose-dependent antifungal and antibacterial effects against and . emerged as a promising candidate for the creation of novel antimicrobial probiotic products targeting dental caries prevention. Further research is warranted to identify the functional metabolites produced by at different dosages when interacting with and .