The Effects of Quorum Sensing Molecules on Streptococcus mutans Biofilm

The use of quorum quenching (QQ) molecules to prevent biofilm formation has recently gained momentum. Interrupting the quorum sensing (QS) pathways of cariogenic bacteria like Streptococcus mutans could reduce the formation of dental plaque on teeth, lowering the incidences of caries and periodontitis.

This research studied the effects of three QQ molecules (p-coumaric acid, tyrosol, and farnesol) on S. mutans biofilm formation on biotic and abiotic surfaces. This research specifically studied the changes in eDNA, protein, carbohydrate, and viable cells in the extracellular matrix (ECM) of the biofilm. The gene expression of gtfb was studied to determine if the QQ molecules played a role in gene expression.

All three QQ molecules showed reduction on different components of the S. mutans biofilm. Tyrosol reduced the greatest amount of overall biomass when the biofilm was formed on examples of both biotic and abiotic surfaces. Tyrosol also had the highest reduction of proteins in biofilms formed on plastic and the total number of viable cells in biofilms formed on 20% porosity hydroxyapatite (HA) disks. p-Coumaric acid reduced the most eDNA and the number of viable cells in the biofilm when it was formed on plastic. p-Coumaric acid also decreased the eDNA and carbohydrate concentrations the most in biofilms formed on 20% porosity HA disks. Additionally, p-coumaric acid reduced the number of viable cells in the biofilm formed on full density HA disks. Farnesol decreased the most carbohydrates concentration on both plastic and full density HA disks. Farnesol decreased the most eDNA on full density HA disks. Farnesol was the only QQ molecule to lower the gene expression of gtfb in the biofilm.

All three QQ molecules decreased some individual components of the S. mutans biofilm, but tyrosol was the overall best QQ molecule for total lessening of biomass and components of the ECM.