1887

Abstract

produces a number of extracellular sucrose-metabolizing enzymes that contribute to the ability of the organism to cause dental caries, including three glucosyltransferases, the products of the , and genes, and a fructosyltransferase, encoded by the gene. To better understand the regulation of the expression of these genes under environmental conditions that more closely mimic those in dental plaque, two strains of harbouring fusions of the (SMS102) and (SMS101) promoters to a chloramphenicol acetyltransferase (CAT) gene were examined in biofilms formed . The strains were grown in a Rototorque biofilm reactor in a tryptone-yeast extract-sucrose medium. CAT specific activity in biofilm cells was measured at quasi-steady state or following additions of 25 mM sucrose or glucose, with or without pH control. After approximately 10 generations of biofilm growth, the and genes of were found to be expressed at levels different from those reported for planktonic cells growing under otherwise similar conditions. The expression of these genes was induced by the addition of sucrose to the quasi-steady-state cultures. Expression of the genes was influenced by environmental pH, since CAT specific activities in quasi-steady-state biofilms of strain SMS102 grown without pH control were twice those produced by cells grown with pH control. Moreover, addition of glucose to quasi-steady-state biofilms resulted in increased expression of the fusion, although the magnitude of the induction was less than that seen with sucrose. The effect of pH on expression was negligible. A modest and transient induction of was observed in biofilms pulsed with excess glucose and the kinetics and level of induction of by excess carbohydrate were dependent on the pH of the biofilms. This study demonstrates that the type and amount of carbohydrate and the environmental pH have a major influence on transcription of the and genes when the organisms are growing in biofilms, and provides evidence for previously undisclosed regulatory circuits for exopolysaccharide gene expression in .

Loading

Article metrics loading...

/content/journal/micro/10.1099/00221287-147-10-2841
2001-10-01
2019-10-17
Loading full text...

Full text loading...

/deliver/fulltext/micro/147/10/1472841a.html?itemId=/content/journal/micro/10.1099/00221287-147-10-2841&mimeType=html&fmt=ahah

References

  1. Bowden, G. H. & Hamilton, I. R. ( 1998; ). Survival of oral bacteria. Crit Rev Oral Biol Med 9, 54-85.[CrossRef]
    [Google Scholar]
  2. Bradford, M. M. ( 1976; ). A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Anal Biochem 72, 248-254.[CrossRef]
    [Google Scholar]
  3. Burne, R. A. ( 1998a; ). Oral streptococci: products of their environment. J Dent Res 77, 445-452.[CrossRef]
    [Google Scholar]
  4. Burne, R. A. ( 1998b; ). Regulation of gene expression in adherent populations of oral streptococci. In Microbial Pathogenesis: Current and Emerging Issues , pp. 55-70. Edited by D. J. LeBlanc, M. S. Lantz & L. M. Switalski. Indianapolis, IN:Indiana University Press.
  5. Burne, R. A. & Chen, Y. M. ( 1998; ). The use of continuous flow bioreactors to explore gene expression and physiology of suspended and adherent populations of oral streptococci. Methods Cell Sci 20, 181-190.[CrossRef]
    [Google Scholar]
  6. Burne, R. A., Schilling, K., Bowen, W. H. & Yasbin, R. E. ( 1987; ). Expression, purification, and characterization of an exo-beta-d-fructosidase of Streptococcus mutans. J Bacteriol 169, 4507-4517.
    [Google Scholar]
  7. Burne, R. A., Chen, Y. M., Wexler, D. L., Kuramitsu, H. & Bowen, W. H. ( 1996; ). Cariogenicity of Streptococcus mutans strains with defects in fructan metabolism assessed in a program-fed specific-pathogen-free rat model. J Dent Res 75, 1572-1577.[CrossRef]
    [Google Scholar]
  8. Burne, R. A., Chen, Y. M. & Penders, J. E. ( 1997; ). Analysis of gene expression in Streptococcus mutans in biofilms in vitro. Adv Dent Res 11, 100-109.[CrossRef]
    [Google Scholar]
  9. Carlsson, J. ( 1984; ). Regulation of sugar metabolism in relation to the ‘feast-and famine’ existence of plaque. In Cariology , pp. 205-211. Edited by B. Guggenheim. Basel:Karger.
  10. Chen, Y. M., Weaver, C. A., Mendelsohn, D. R. & Burne, R. A. ( 1998; ). Transcriptional regulation of the Streptococcus salivarius 57.I urease operon. J Bacteriol 180, 5769-5775.
    [Google Scholar]
  11. Dubois, M., Gilles, K. A., Hamilton, J. K., Rebers, P. A. & Smith, F. ( 1956; ). Colorimetric method for the determination of sugar and related substances. Anal Chem 28, 350-356.[CrossRef]
    [Google Scholar]
  12. Ebisu, S., Keijiro, K., Kotani, S. & Misaka, A. ( 1975; ). Structural differences in the fructans elaborated by Streptococcus mutans and Strep. salivarius. J Biochem 78, 879-887.
    [Google Scholar]
  13. Goodman, S. D. & Gao, Q. ( 2000; ). Characterization of the gtfB and gtfC promoters from Streptococcus mutans GS-5. Plasmid 43, 85-98.[CrossRef]
    [Google Scholar]
  14. Hamada, S. & Slade, H. D. ( 1980; ). Biology, immunology, and cariogenicity of Streptococcus mutans. Microbiol Rev 44, 331-384.
    [Google Scholar]
  15. Hudson, M. C. & Curtiss, R.III ( 1990; ). Regulation of expression of Streptococcus mutans genes important to virulence. Infect Immun 58, 464-470.
    [Google Scholar]
  16. Kiska, D. L. & Macrina, F. L. ( 1994; ). Genetic regulation of fructosyltransferase in Streptococcus mutans. Infect Immun 62, 1241-1251.
    [Google Scholar]
  17. Koch, A. L. ( 1994; ). Growth measurement. In Methods for General and Molecular Bacteriology , pp. 249-276. Edited by P. Gerhardt, R. G. E. Murray, W. A. Wood & N. R. Krieg. Washington, DC:American Society for Microbiology.
  18. Kuramitsu, H. K. ( 1993; ). Virulence factors of mutans streptococci: role of molecular genetics. Crit Rev Oral Biol Med 4, 159-176.
    [Google Scholar]
  19. Li, Y. H., Chen, Y. M. & Burne, R. A. ( 2000; ). Regulation of urease gene expression by Streptococcus salivarius growing in biofilms. Environ Microbiol 2, 169-177.[CrossRef]
    [Google Scholar]
  20. Li, Y. H., Lau, P. C., Lee, J. H., Ellen, R. P. & Cvitkovitch, D. G. ( 2001; ). Natural genetic transformation of Streptococcus mutans growing in biofilms. J Bacteriol 183, 897-908.[CrossRef]
    [Google Scholar]
  21. Liljemark, W. F. & Bloomquist, C. ( 1996; ). Human oral microbial ecology and dental caries and periodontal diseases. Crit Rev Oral Biol Med 7, 180-198.[CrossRef]
    [Google Scholar]
  22. Loesche, W. J. & Syed, S. A. ( 1973; ). The predominant cultivable flora of carious plaque and carious dentine. Caries Res 7, 201-216.[CrossRef]
    [Google Scholar]
  23. Nakano, Y. J. & Kuramitsu, H. K. ( 1992; ). Mechanism of Streptococcus mutans glucosyltransferase: hybrid-enzyme analysis. J Bacteriol 174, 5639-5646.
    [Google Scholar]
  24. Shaw, W. V. ( 1979; ). Chloramphenicol acetyltransferase activity from chloramphenicol-resistant bacteria. Methods Enzymol 43, 737-755.
    [Google Scholar]
  25. Shiroza, T. & Kuramitsu, H. K. ( 1988; ). Sequence analysis of the Streptococcus mutans fructosyltransferase gene and flanking regions. J Bacteriol 170, 810-816.
    [Google Scholar]
  26. Wexler, D. L., Hudson, M. C. & Burne, R. A. ( 1993; ). Streptococcus mutans fructosyltransferase (ftf) and glucosyltransferase (gtfBC) operon fusion strains in continuous culture. Infect Immun 61, 1259-1267.
    [Google Scholar]
  27. Yamashita, Y., Bowen, W. H., Burne, R. A. & Kuramitsu, H. K. ( 1993; ). Role of the Streptococcus mutans gtf genes in caries induction in the specific-pathogen-free rat model. Infect Immun 61, 3811-3817.
    [Google Scholar]
http://instance.metastore.ingenta.com/content/journal/micro/10.1099/00221287-147-10-2841
Loading
/content/journal/micro/10.1099/00221287-147-10-2841
Loading

Data & Media loading...

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error