Genetic and Phenotypic Characterization of adhE gene in Streptococcus mutans

Objective: Streptococcus mutans is a primary pathogen for dental caries. The ability of S. mutans to produce bacteriocins, called mutacins, plays an important role in its competition with other non-pathogenic streptococcal species in the oral biofilm. Previous study utilizing a random mutagenesis library screening identified 25 genes involved in regulation of mutacin production. One of gene is adhE, encoding a homolog of alcohol-acetaldehyde dehydrogenase. The purpose of this study was to further characterize the adhE gene, in order to understand its role in mutacin gene regulation. Methods: A mutant of the adhE gene was generated via allelic exchange replacing the adhE gene with a kanamycin resistance cassette. The effects of adhE deletion on mutacin production, cell growth, and biofilm formation were analyzed. Results: Deletion of the adhE gene diminished mutacin production, altered biofilm architecture of the mutant strain, and reduced cell growth rate to 55% of the wild-type level. Conclusion: The adhE gene probably plays a role not only in mutacin production, but also in other important biological functions such as cell growth and biofilm formation. Support: this project is supported by NIH grant R01 DE 014757, and The J. Dean Roberts Society.