Functional Genomics of Streptococcus mutans: Identifying Critical Genes for Oral Biofilm Formation

Cara E. Pirani

Streptococcus mutans (S. mutans) is a pathogen found in the human oral cavity that plays a central role in the development of dental caries, or tooth decay. This pathogen thrives on the sugars consumed in the diet, contributing to the breakdown of tooth enamel, especially in the presence of poor oral hygiene. S. mutans produces a glycosyltransferase enzyme that converts sucrose into the polysaccharide glucan. Glucan allows the pathogen to attach to the enamel of the tooth and begin metabolizing the sugar on the teeth, resulting in lactic acid. The acid under the biofilm layer lowers the pH of the tooth and demineralizes the enamel, causing tooth decay. Previous research within the Shields lab isolated ninety biofilm-deficient samples. Our project is aimed at determining which of these samples have intact gtfBC genes, which are critical for S. mutans biofilm formation. We are accomplishing this through DNA extraction and genomic analysis through PCR and gel electrophoresis. Once the biofilm-defective mutants with gtfBC bands are isolated, we intend to use genome sequencing to identify which genetic insertions are required for S. mutans to attach to the tooth surface. This research retards caries formation and will greatly improve oral health for all people.