Molecular Modulation of Single and Multi-species Biofilm Formation by Orally-associated Bacteria

Biofilms are aggregates of bacterial cells attached to a surface. Oral biofilms (" plague ") are major contributors to tooth decay (dental caries) and are a potential conduit for infection and disease. These biofilms have been shown to be resistant to removal by traditional oral hygiene practices. Novel prophylactic and in situ treatment methods are therefore needed to address this problem. While Oral biofilms have been shown to contain hundreds of species of bacteria we focus on three relevant organisms: Streptococcus mutans, Streptococcus sanguinis, and Actinomyces naeslundii (A. oris). Of the many bacteria involved in cavity formation and tooth decay, S. mutans is recognized as the principle causative agent and pioneer. S. sanguinis and A. oris are pioneer-colonizing commensal organisms that are involved in the initial establishment of oral biofilms and are associated with significant human diseases including endocarditis and actinomycosis. Our group previously identified small organic molecule inhibitors of biofilm formation in Pseudomonas aeruginosa. We hypothesize that these compounds directly affect cell-to-cell signaling (" quorum sensing ") pathways that are involved in biofilm formation. Presently, members of our lab have tested the efficacy of similar compounds on the three individual aforementioned strains. In this work, we focus on how these organic compounds interact with communal biofilms consisting of two or more strains.