Project Summary In this project we will construct a powerful new tool to systematically identify infection-relevant genes in the dental caries pathogen Streptococcus mutans. Sequence-defined arrayed mutant libraries are available for several medical and model bacterial species. These tools have greatly accelerated the pace of genetic screens and the identification of important pathogenic genetic determinants. We will construct an arrayed transposon mutant library in the model laboratory strain UA159 and use a sequencing approach to determine the identity of each mutant. After constructing the library, we will use it to study genetic determinants of sucrose-mediated biofilm formation, which is a critical virulence trait of S. mutans. We will also use a comparative transposon sequencing (Tn-seq) approach to identify genes that provide a selective advantage in biofilms. The results of this research will include the following: 1) construction of an arrayed and sequence defined transposon mutant resource for the S. mutans research community, 2) an improved understanding of the genetic determinants of sucrose-mediated biofilm formation both in monoculture and in complex communities, and 3) we expect this knowledge to contribute to the development of new approaches to target and reduce S. mutans colonization of the oral cavity. This project will also provide training opportunities for undergraduate and graduate students from Arkansas, an area that is underrepresented in biomedical research.

Project Narrative Tooth decay is very prevalent in the United States and a leading cause of the disease is the oral bacterium Streptococcus mutans. In this project we will construct a powerful new genetic tool, a sequence-defined transposon mutant library, that can be applied to identify genetic determinants of S. mutans pathogenicity. The results of this project could lead to the discovery of important genetic factors required for S. mutans to cause tooth decay, and lead to new approaches to control S. mutans infections.