Polyphenol Effect On  Streptococcus mutans ComC^- Biofilm

This study investigated the effect that polyphenols have on Streptococcus mutans quorum sensing as it relates to biofilm formation. Polyphenols act as not only antioxidants, but also can be bactericidal. Objectives: The effect of polyphenols on biofilms of a quorum sensing mutant of S. mutans was investigated. A S. mutans ComC^- deficient strain was incubated in different concentrations of competence stimulating peptide (CSP) with epigallocatechin-3 gallate (EGCG) and compared to ComC^- without EGCG to help understand polyphenol’s anti-biofilm effects. Methods: The ComC^- mutant was incubated in Tryptic Soy broth supplemented with 1% sucrose (TSBS) for 2 hours in 96 well microtiter plates. EGCG (0.25mg/mL) was then mixed with dilutions of CSP (0-100µg/mL) in TSBS and added to the ComC^- wells. Controls included wells without EGCG. The biofilm was read using a crystal violet assay after 24hr incubation. Results: The ComC^- mutant incubated with CSP was found to significantly (p<0.05) exhibit more biofilm formation than wells without CSP. However, EGCG was demonstrated to have a significant inhibitory effect on the ComC^- mutant. The 100µg/mL CSP concentration without EGCG demonstrated the highest enhancement of biofilm compared to the corresponding wells with EGCG (72% increase). In addition, the 0µg/mL CSP control without EGCG had 19% greater biofilm than wells with polyphenol.  Conclusion: It is known that CSP is a biofilm agonist for the ComC^- mutant and the EGCG is an antagonist. However, now it can be stated that EGCG in combination with CSP demonstrated a significant decrease in biofilm formation. These results suggest that a polyphenol supplement containing EGCG may be a possible way to decrease the biofilm formation of S. mutans in patients with severe caries risk.  Supported, in part, by the Indiana University School of Dentistry Dental Student Research Fund.