Inhibitory Effects of Streptococcus salivarius LAB813 on Cariogenic Microbial Biofilms

Preliminary results suggest a strain of Streptococcus salivarius, LAB813, inhibits the growth of Streptococcus mutans (MS), a major cariogenic bacterial species. Our purpose was to quantify the inhibitory effects of LAB813 against MS in single and fungal-bacterial biofilms. MS and MS-Candida albicans biofilms were cultivated with glucose or sucrose for 6h or 24h and challenged with LAB813 at low or high cell concentration for 24h. LAB813 was highly effective at killing (>95%) 6h and 24h MS biofilms but not as effective at high cell concentration. In fungal-bacterial biofilms, the killing effect of LAB813 was only observed on mature biofilms. Bacterial extracts of LAB813 were shown to disrupt S. mutans biofilms and allow permeabilization of MS and Micrococcus luteus. LAB813 therefore possesses strong antimicrobial activity, possibly through induction of pore formation in target bacteria. Further work is needed to maximize LAB813 effectiveness against more complex oral polymicrobial biofilms.M.Sc