Metabolic activity of Streptococcus mutans biofilms and gene expression during exposure to xylitol and sucrose
| Autor: | Christian Klein, Christiane von Ohle, Eva-Maria Decker, Dimitri Schwindt |
|---|---|
| Rok vydání: | 2014 |
| Předmět: |
Sucrose
Time Factors extracellular polysaccharides Genotype Tetrazolium Salts Cariogenic Agents Biology Carbohydrate metabolism Xylitol Polysaccharide Gene Expression Regulation Enzymologic Microbiology Streptococcus mutans chemistry.chemical_compound Humans 5-cyano-2 3-ditolyl tetrazolium chloride Dental Enamel Sugar General Dentistry Fluorescent Dyes chemistry.chemical_classification Bacteriological Techniques Microbial Viability Microscopy Confocal viability Polysaccharides Bacterial Biofilm food and beverages Gene Expression Regulation Bacterial biology.organism_classification Bacterial Load Culture Media Up-Regulation carbohydrates (lipids) Glucose chemistry Glucosyltransferases Biofilms Sweetening Agents gene expression Original Article Bacteria |
| Zdroj: | International Journal of Oral Science |
| ISSN: | 2049-3169 1674-2818 |
| DOI: | 10.1038/ijos.2014.38 |
| Popis: | The objective of the study was to analyse Streptococcus mutans biofilms grown under different dietary conditions by using multifaceted methodological approaches to gain deeper insight into the cariogenic impact of carbohydrates. S. mutans biofilms were generated during a period of 24 h in the following media: Schaedler broth as a control medium containing endogenous glucose, Schaedler broth with an additional 5% sucrose, and Schaedler broth supplemented with 1% xylitol. The confocal laser scanning microscopy (CLSM)-based analyses of the microbial vitality, respiratory activity (5-cyano-2,3-ditolyl tetrazolium chloride, CTC) and production of extracellular polysaccharides (EPS) were performed separately in the inner, middle and outer biofilm layers. In addition to the microbiological sample testing, the glucose/sucrose consumption of the biofilm bacteria was quantified, and the expression of glucosyltransferases and other biofilm-associated genes was investigated. Xylitol exposure did not inhibit the viability of S. mutans biofilms, as monitored by the following experimental parameters: culture growth, vitality, CTC activity and EPS production. However, xylitol exposure caused a difference in gene expression compared to the control. GtfC was upregulated only in the presence of xylitol. Under xylitol exposure, gtfB was upregulated by a factor of 6, while under sucrose exposure, it was upregulated by a factor of three. Compared with glucose and xylitol, sucrose increased cell vitality in all biofilm layers. In all nutrient media, the intrinsic glucose was almost completely consumed by the cells of the S. mutans biofilm within 24 h. After 24 h of biofilm formation, the multiparametric measurements showed that xylitol in the presence of glucose caused predominantly genotypic differences but did not induce metabolic differences compared to the control. Thus, the availability of dietary carbohydrates in either a pure or combined form seems to affect the cariogenic potential of S. mutans biofilms. Sucrose sugar and xylitol sweetener both activate genes involved in tooth decay in a bacterium commonly found in the human mouth. Eva-Maria Decker and her colleagues at the University of Tubingen, Germany, cultured Streptococcus mutans in a glucose-rich broth and in the same broth containing sucrose or xylitol. The bacteria formed complex communities called biofilms under all three conditions. The presence of sucrose increased the bacteria’s metabolic activity throughout the various biofilm layers. Despite previous claims that xylitol helps prevent cavities, the natural sweetener did not affect bacterial viability. Both sucrose- and xylitol-supplemented media led to increased expression of several genes involved in biofilm formation. The study, one of only a few concerning the effects of xylitol on S. mutans biofilms, calls into question the effectiveness of xylitol in preventing tooth decay. |
| Databáze: | OpenAIRE |
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