Tooth decay is one of the most important problems societie. the activity of acid producing bacteria, especially Streptococcus mutans, is the main cause of this complication. The creation of the biofilms of the bacterium is subject to the presence of a specific enzyme called glucan sucrase or glucosyltransferase, coded by gtf gene. The aim of this study was to evaluate the genes of GtfB and GtfC of Streptococcus mutans in the formation of dental plaque biofilm.Material & Mthod: . In study, the biofilm was formed on a polystyrene surface using a microtiter plate and stained. In order to confirm Streptococcus mutans colonies, biochemical and fermentative tests were performed. DNA extraction from the kit of gram-positive bacteria (Cinna Pure DNA KIT-PR881614) was used to extract DNA. To evaluate the PCR product, the samples were transferred to 1% agarose gel examined staining. optimum pH and the effect of different concentrations of sucrose on bacterial growth were measured at 630 nm using spectropHotometer.
The results showed that out of 46 samples, 19 isolates (41.30%) had gtfB gene and 8 (17.4%) had gtfC gene. The absorbance of the biofilm produced by the samples is different and the highest absorption is 1.43. In this study, the highest growth rate of Streptococcus mutans isolated from tooth plaque was obtained at a concentration of 0.5 g / L sucrose and pH = 4.5.
Therefore, sucrose sugar, which is commonly found in the diet, causes the growth of Streptococcus mutans