Collagen Peptide in a Combinatorial Treatment with Lactobacillus rhamnosus Inhibits the Cariogenic Properties of Streptococcus mutans : An In Vitro Study

Dental caries is caused by the formation of cariogenic biofilm, leading to localized areas of enamel demineralization. , a cariogenic pathogen, has long been considered as a microbial etiology of dental caries. We hypothesized that an antagonistic approach using a prebiotic collagen peptide in combination with probiotic would modulate the virulence of this cariogenic biofilm. In vitro biofilms were formed on saliva-coated hydroxyapatite discs, and the inhibitory effect of a combination of and collagen peptide on biofilms were evaluated using microbiological, biochemical, confocal imaging, and transcriptomic analyses. The combination of with collagen peptide altered acid production by , significantly increasing culture pH at an early stage of biofilm formation. Moreover, the 3D architecture of the biofilm was greatly compromised when it was in the presence of with collagen peptide, resulting in a significant reduction in exopolysaccharide with unstructured and mixed bacterial organization. The presence of with collagen peptide modulated the virulence potential of via down-regulation of , , and corresponding to acid production and proton transportation, whereas associated with alkali production was up-regulated. Gly-Pro-Hyp, a common tripeptide unit of collagen, consistently modulated the cariogenic potential of by inhibiting acid production, similar to the bioactivity of a collagen peptide. It also enhanced the relative abundance of commensal streptococci ( ) in a mixed-species biofilm by inhibiting colonization and dome-like microcolony formation. This work demonstrates that food-derived synbiotics may offer a useful means of disrupting cariogenic communities and maintaining microbial homeostasis.