Genotypic diversity of S. mutans in dental biofilm formed in situ under sugar stress exposure

• Published in: Brazilian dental journal Vol. 18; no. 3; p. 185
• Main Authors: Arthur, Rodrigo Alex, Tabchoury, Cínthia Pereira Machado, Mattos-Graner, Renata de Oliveira, Del Bel Cury, Altair A, Paes Leme, Adriana Franco, Vale, Gláuber Campos, Cury, Jaime Aparecido
• Format: Journal Article
• Language: English
• Published: Brazil 2007
• Subjects: Bacterial Typing Techniques; Biofilms - growth & development; Colony Count, Microbial; Cross-Over Studies; Dental Enamel - microbiology; Dietary Carbohydrates - metabolism; DNA, Bacterial - analysis; Double-Blind Method; Genetic Variation; Genotype; Humans; Monosaccharides - metabolism; Mouth - microbiology; Reference Values; Species Specificity; Streptococcus mutans - genetics; Streptococcus mutans - growth & development; Streptococcus mutans - metabolism; Stress, Physiological; Sucrose - metabolism
• ISSN: 1806-4760

In situ dental biofilm composition under sugar exposure is well known, but sugar effect on the genotypic diversity of S. mutans in dental biofilm has not been explored. This study evaluated S. mutans genotypic diversity in dental biofilm formed in situ under frequent exposure to sucrose and its monosaccharide constituents (glucose and fructose). Saliva of 7 volunteers was collected for isolation of S. mutans and the same volunteers wore intraoral palatal appliances, containing enamel slabs, which were submitted to the following treatments: distilled and deionized water (negative control), 10% glucose + 10% fructose (fermentable carbohydrates) solution or 20% sucrose (fermentable and EPS inductor) solution, 8x/day. After 3, 7 and 14 days, the biofilms were collected and S. mutans colonies were isolated. Arbitrarily primed polymerase chain reaction (AP-PCR) of S. mutans showed that salivary genotypes were also detected in almost all biofilm samples, independently of the treatment, and seemed to reflect those genotypes present at higher proportion in biofilms. In addition to the salivary genotypes, others were found in biofilms but in lower proportions and were distinct among treatment. The data suggest that the in situ model seems to be useful to evaluate genotypic diversity of S. mutans, but, under the tested conditions, it was not possible to clearly show that specific genotypes were selected in the biofilm due to the stress induced by sucrose metabolism or simple fermentation of its monosaccharides.