Inhibitory effect of probiotic lactobacilli against Streptococcus mutans and Porphyromonas gingivalis biofilms

Background: Lactobacillus reuteri and Lactobacillus casei have been proposed as probiotic bacteria that promote oral health. Objectives: The present study aimed to evaluate the in vitro effects of L. reuteri and L. casei on the biofilm formation of major oral pathogens, Streptococcus mutans and Porphyromonas gingivalis. Materials and Methods: L. casei strain Shirota and L. reuteri ATCC 55730 were isolated from the commercial products and cultured in de Man, Rogosa, and Sharpe broth. Polymerase chain reaction was used to confirm the identity of the species. S. mutans ATCC 25175 and P. gingivalis ATCC 33277 were cultured in brain–heart infusion broth and used for biofilm formation on 96-well microplate platform. The biofilms were treated with the probiotics and appropriate controls in a time-dependent experiment from 15 min to 24 h. The biofilm biomass was evaluated using crystal violet and safranin. Results: The statistical analysis showed a significant reduction in the S. mutans and P. gingivalis biofilms after treatment with the L. reuteri and L. casei probiotics at all incubation times (P < 0.05). Conclusion: The present study demonstrated the potential antibiofilm activity of L. casei strain Shirota and L. reuteri ATCC 55730 against S. mutans and P. gingivalis biofilms in vitro. The foregoing data have formed a basis for future clinical studies to evaluate the beneficial oral health effect of probiotic Lactobacilli strains.