This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Paddick, J. S. Articles by Beighton, D. Search for Related Content PubMed PubMed Citation Articles by Paddick, J. S. Articles by Beighton, D. Agricola Articles by Paddick, J. S. Articles by Beighton, D.

 Previous Article  |  Next Article 

Applied and Environmental Microbiology, November 2003, p. 6475-6480, Vol. 69, No. 11
0099-2240/03/$08.00+0     DOI: 10.1128/AEM.69.11.6475-6480.2003
Copyright © 2003, American Society for Microbiology. All Rights Reserved.

Effect of the Environment on Genotypic Diversity of Actinomyces naeslundii and Streptococcus oralis in the Oral Biofilm

Department of Microbiology, Guy's, King's, and St. Thomas' Dental Institute, King's College London, London, United Kingdom

Received 12 June 2003/ Accepted 26 August 2003

The genotypic diversity of Actinomyces naeslundii genospecies 2 (424 isolates) and Streptococcus oralis (446 isolates) strains isolated from two sound approximal sites in all subjects who were either caries active (seven subjects) or caries free (seven subjects) was investigated by using the repetitive extragenic palindromic PCR. The plaque from the caries-active subjects harbored significantly greater proportions of mutans streptococci and lactobacilli and a smaller proportion of A. naeslundii organisms than the plaque sampled from the caries-free subjects. These data confirmed that the sites of the two groups of subjects were subjected to different environmental stresses, probably determined by the prevailing or fluctuating acidic pH values. We tested the hypothesis that the microfloras of the sites subjected to greater stresses (the plaque samples from the caries-active subjects) would exhibit reduced genotypic diversity since the sites would be less favorable. We found that the diversity of A. naeslundii strains did not change (2 = 0.68; P = 0.41) although the proportional representation of A. naeslundii was significantly reduced (P < 0.05). Conversely, the diversity of the S. oralis strains increased (2 = 11.71; P = 0.0006) and the proportional representation of S. oralis did not change. We propose that under these environmental conditions the diversity and number of niches within the oral biofilm that could be exploited by S. oralis increased, resulting in the increased genotypic diversity of this species. Apparently, A. naeslundii was not able to exploit the new niches since the prevailing conditions within the niches may have been deleterious and not supportive of its proliferation. These results suggest that environmental stress may modify a biofilm such that the diversity of the niches is increased and that these niches may be successfully exploited by some, but not necessarily all, members of the microbial community.

This article has been cited by other articles:

• Paddick, J. S., Brailsford, S. R., Rao, S., Soares, R. F., Kidd, E. A. M., Beighton, D., Homer, K. A. (2006). Effect of Biofilm Growth on Expression of Surface Proteins of Actinomyces naeslundii Genospecies 2.. Appl. Environ. Microbiol. 72: 3774-3779 [Abstract] [Full Text]  
• Kamiya, R. U, Napimoga, M. H, Hofling, J. F, Goncalves, R. B (2005). Frequency of four different mutacin genes in Streptococcus mutans genotypes isolated from caries-free and caries-active individuals. J Med Microbiol 54: 599-604 [Abstract] [Full Text]  
• Paddick, J. S., Brailsford, S. R., Kidd, E. A. M., Beighton, D. (2005). Phenotypic and Genotypic Selection of Microbiota Surviving under Dental Restorations. Appl. Environ. Microbiol. 71: 2467-2472 [Abstract] [Full Text]  
• Nadkarni, M. A., Caldon, C. E., Chhour, K.-L., Fisher, I. P., Martin, F. E., Jacques, N. A., Hunter, N. (2004). Carious Dentine Provides a Habitat for a Complex Array of Novel Prevotella-Like Bacteria. J. Clin. Microbiol. 42: 5238-5244 [Abstract] [Full Text]