Oral Biofilm Dispersal Strategies

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The human oral cavity harbours a species-rich microbiota of greater than 750 bacterial species, the majority of which are embedded in an extracellular polymeric substance as dental plaque biofilms. Microorganisms in this complex and competitive environment experiences continuous stress and fluctuations: oxygen availability, changes in pH, redox potential, salinity, water and biochemical activity of saliva, short term extreme temperature conditions, and at times nutrient starved and nutrient rich periods. Because of this environmental instability, successful microbial occupation relies on two principal strategies: i) establishment of specific cell-cell interactions that lead to intraspecies co-dependence, and ii) entrenchment in recalcitrant biofilms as dental plaque. To characterize the features of microbial dispersive events, we have selected a model consortium of three well recognized oral bacteria known as the red complex, which consists of Porphyromonas gingivalis, Tannerella forsythia and Treponema denticola. Our research will focus on two classes of enzymes that have been implicated in biofilm dispersal in other niches including carbohydrate-dispersins and extracellular nucleases, with a working hypothesis that they may be responsible for red complex biofilm remodelling. To achieve this goal, and to put our results into biological context, we will implement a bottom-up approach of structural and functional characterization of enzymes that may contribute to biofilm dispersal, as well as a top-down approach of tracking the impacts of these enzymes to biofilm morphology through microfluidic, in vitro analyses. In general, the characterization of biofilm dispersal processes have a strong likelihood to inform a unique state in the bacterial lifecycle. To our knowledge, our experimental approach to characterize keystone biofilm dispersal by the oral microbiome is unique in Canada.