The Role of Extracellular Polysaccharides Matrix in Virulent Oral Biofilms
Marlise l. Klein, Megan L. Falsetta, Xiao J, William H. Bowen and Hyun Koo
from: Oral Microbial Ecology: Current Research and New Perspectives (Edited by: Nicholas S. Jakubovics and Robert J. Palmer Jr.). Caister Academic Press, U.K. (2013)
Virulent biofilms are responsible for a range of infections, including those occurring in the mouth. The disease dental caries is a prime example of the consequences arising from interactions of host, bacteria and diet (sugars), resulting in the assembly of pathogenic biofilms on susceptible tooth-surfaces. All biofilms harbor a microbial-derived extracellular-matrix. The exopolysaccharides (EPS) formed on the tooth-pellicle and on the bacterial surfaces provide binding sites for microorganisms; eventually the accumulated EPS enmeshes the microbial cells. The metabolic activity of the bacteria embedded in EPS-rich and diffusion-limited matrix leads to acidification of the milieu, and subsequent onset of the disease through acid dissolution of enamel (expressed clinically as cavities). This chapter focuses on the mechanisms through which the EPS produced by Streptococcus mutans modulates the assembly of a spatially complex 3D matrix during biofilm morphogenesis within a mixed-bacterial species community. The architecture of the matrix influences the development of pH heterogeneity in the 3D environment of intact biofilms. The matrix facilitates the formation of structured acidic-microenvironments in close proximity to the apatite-surface, which are essential for the evolution of virulent biofilms formed on the tooth. These observations may have relevance beyond the mouth, as matrix is inherent to all biofilms read more ...