The Exopolysaccharide Matrix: A Virulence Determinant of Cariogenic Biofilm

J Dent Res. 2013 Dec;92(12):1065-73. doi: 10.1177/0022034513504218. Epub 2013 Sep 17.

Abstract

Many infectious diseases in humans are caused or exacerbated by biofilms. Dental caries is a prime example of a biofilm-dependent disease, resulting from interactions of microorganisms, host factors, and diet (sugars), which modulate the dynamic formation of biofilms on tooth surfaces. All biofilms have a microbial-derived extracellular matrix as an essential constituent. The exopolysaccharides formed through interactions between sucrose- (and starch-) and Streptococcus mutans-derived exoenzymes present in the pellicle and on microbial surfaces (including non-mutans) provide binding sites for cariogenic and other organisms. The polymers formed in situ enmesh the microorganisms while forming a matrix facilitating the assembly of three-dimensional (3D) multicellular structures that encompass a series of microenvironments and are firmly attached to teeth. The metabolic activity of microbes embedded in this exopolysaccharide-rich and diffusion-limiting matrix leads to acidification of the milieu and, eventually, acid-dissolution of enamel. Here, we discuss recent advances concerning spatio-temporal development of the exopolysaccharide matrix and its essential role in the pathogenesis of dental caries. We focus on how the matrix serves as a 3D scaffold for biofilm assembly while creating spatial heterogeneities and low-pH microenvironments/niches. Further understanding on how the matrix modulates microbial activity and virulence expression could lead to new approaches to control cariogenic biofilms.

Keywords: Streptococcus mutans; dental caries; extracellular matrix; glucosyltransferases; heterogeneity; pH microenvironment.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Review

MeSH terms

  • Biofilms*
  • Cellular Microenvironment / physiology
  • Dental Caries / microbiology*
  • Dental Plaque / microbiology
  • Humans
  • Hydrogen-Ion Concentration
  • Polysaccharides, Bacterial / physiology*
  • Streptococcus mutans / pathogenicity*
  • Streptococcus mutans / physiology
  • Virulence

Substances

  • Polysaccharides, Bacterial