title: Protein expression by planktonic and biofilm cells of Streptococcus mutans.
abstract: Streptococcus mutans, a major causal agent of dental caries, functions in nature as a component of a biofilm on teeth (dental plaque) and yet very little information is available on the physiology of the organism in such surface-associated communities. As a consequence, we undertook to examine the synthesis of proteins by planktonic and biofilm cells growing in a biofilm chemostat at pH 7.5 at a dilution rate of 0.1 h(-1) (mean generation time=7 h). Cells were incubated with (14)C-labelled amino acids, the proteins extracted and separated by two-dimensional electrophoresis followed by autoradiography and computer-assisted image analysis. Of 694 proteins analysed, 57 proteins were enhanced 1.3-fold or greater in biofilm cells compared to planktonic cells with 13 only expressed in sessile cells. Diminished protein expression was observed with 78 proteins, nine of which were not expressed in biofilm cells. The identification of enhanced and diminished proteins by mass spectrometry and computer-assisted protein sequence analysis revealed that, in general, glycolytic enzymes involved in acid formation were repressed in biofilm cells, while biosynthetic processes were enhanced. The results show that biofilm cells possess novel proteins, of as yet unknown function, that are not present in planktonic cells.
authors.affiliation: Department of Oral Biology, Centre for Oral Health Sciences, Malmö University, Malmö, Sweden. gunnel.svensater@od.mah.se
authors.forename: G
authors.initials: G
authors.lastname: Svensäter
authors.forename: J
authors.initials: J
authors.lastname: Welin
authors.forename: J C
authors.initials: JC
authors.lastname: Wilkins
authors.forename: D
authors.initials: D
authors.lastname: Beighton
authors.forename: I R
authors.initials: IR
authors.lastname: Hamilton
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D018441:Biofilms / Q000254:growth & development*; D003470:Culture Media; D003731:Dental Caries / Q000382:microbiology; D015180:Electrophoresis, Gel, Two-Dimensional; D006801:Humans; D007091:Image Processing, Computer-Assisted; D010933:Plankton / Q000378:metabolism*; D013295:Streptococcus mutans / Q000254:growth & development* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D003470:Culture Media