Up-regulation of competence- but not stress-responsive proteins accompanies an altered metabolic phenotype in Streptococcus mutans biofilms

Microbiology (Reading). 2005 Jun;151(Pt 6):1823-1837. doi: 10.1099/mic.0.27830-0.


Mature biofilm and planktonic cells of Streptococcus mutans cultured in a neutral pH environment were subjected to comparative proteome analysis. Of the 242 protein spots identified, 48 were significantly altered in their level of expression (P<0.050) or were unique to planktonic or biofilm-grown cells. Among these were four hypothetical proteins as well as proteins known to be associated with the maintenance of competence or found to possess a cin-box-like element upstream of their coding gene. Most notable among the non-responsive genes were those encoding the molecular chaperones DnaK, GroEL and GroES, which are considered to be up-regulated by sessile growth. Analysis of the rest of the proteome indicated that a number of cellular functions associated with carbon uptake and cell division were down-regulated. The data obtained were consistent with the hypothesis that a reduction in the general growth rate of mature biofilms of S. mutans in a neutral pH environment is associated with the maintenance of transformation without the concomitant stress response observed during the transient state of competence in bacterial batch cultures.

Publication types

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

MeSH terms

  • Adaptation, Physiological / genetics
  • Bacterial Proteins / analysis
  • Bacterial Proteins / biosynthesis*
  • Biofilms*
  • Electrophoresis, Gel, Two-Dimensional
  • Gene Expression Regulation, Bacterial*
  • Proteome / analysis*
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  • Streptococcus mutans / genetics*
  • Streptococcus mutans / growth & development
  • Streptococcus mutans / physiology*


  • Bacterial Proteins
  • Proteome