Bacteria are ubiquitous in nature and contribute to human health and disease, but antibiotic-resistant pathogens pose a significant public health threat. Despite decades of research, 25-50% of bacterial genes (even in the best studied model organisms) remain uncharacterized. However, these genes (the “dark matter” of bacterial genomes) are often differentially expressed or important for fitness in biofilms and infections. The overarching goals of our research are to discover functions for poorly characterized bacterial genes and to understand how bacteria interact with their environment. We use genetic, biochemical, and computational tools to understand the underpinnings of bacterial biofilm formation, polymicrobial interactions and competition, and uncharacterized gene function. Our work primarily focuses on the Gram-positive commensal and pathogen Enterococcus faecalis. We are also interested in the development and distribution of biological tools such as arrayed transposon libraries. Our work has important implications for fundamental bacteriology, the ecology of commensal microbiomes, treatment of biofilm-associated and polymicrobial infections, and biofilm-associated antibiotic resistance.