Streptococcus gordonii comCDE (competence) operon modulates biofilm formation with Candida albicans

Microbiology (Reading). 2015 Feb;161(Pt 2):411-421. doi: 10.1099/mic.0.000010. Epub 2014 Dec 10.

Abstract

Candida albicans is a pleiomorphic fungus that forms mixed species biofilms with Streptococcus gordonii, an early colonizer of oral cavity surfaces. Activation of quorum sensing (QS; intercellular signalling) promotes monospecies biofilm development by these micro-organisms, but the role of QS in mixed species communities is not understood. The comCDE genes in S. gordonii encode a sensor-regulator system (ComDE), which is activated by the comC gene product (CSP, competence stimulating peptide) and modulates expression of QS-regulated genes. Dual species biofilms of S. gordonii ΔcomCDE or ΔcomC mutants with C. albicans showed increased biomass compared to biofilms of S. gordonii DL1 wild-type with C. albicans. The ΔcomCDE mutant dual species biofilms in particular contained more extracellular DNA (eDNA), and could be dispersed with DNase I or protease treatment. Exogenous CSP complemented the S. gordonii ΔcomC transformation deficiency, as well as the ΔcomC-C. albicans biofilm phenotype. Purified CSP did not affect C. albicans hyphal filament formation but inhibited monospecies biofilm formation by C. albicans. The results suggest that the S. gordonii comCDE QS-system modulates the production of eDNA and the incorporation of C. albicans into dual species biofilms.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Biofilms*
  • Candida albicans / genetics
  • Candida albicans / physiology*
  • Candidiasis / microbiology*
  • DNA, Bacterial / genetics
  • DNA, Bacterial / metabolism
  • Humans
  • Operon*
  • Quorum Sensing
  • Streptococcal Infections / microbiology*
  • Streptococcus gordonii / genetics
  • Streptococcus gordonii / physiology*

Substances

  • Bacterial Proteins
  • DNA, Bacterial