Abstract
The mouth presents a multiplicity of local environments in communication with one another via saliva. The spatial organization of microbes within the mouth is shaped by opposing forces in dynamic equilibrium-salivary flow and adhesion, shedding and colonization-and by interactions among and between microbes and the host. Here we review recent evidence confirming that oral microbes are specialized for individual habitats within the mouth and that microbial habitats and niches are defined by micron-scale gradients in combination with short- and long-range interactions. Micron-scale structure illuminates the roles of individual taxa and provides insight into their community ecology and potential pathogenicity.