The role of Treponema denticola motility in synergistic biofilm formation with Porphyromonas gingivalis

In the human oral cavity Porphyromonas gingivalis and Treponema denticola dominated biofilm communities are associated with the progression and severity of chronic periodontitis and these two species display synergistic virulence in animal models. These two phylogenetically distant bacteria have evolved in close contact over millennia. T. denticola is a motile spirochaete that is adapted to moving through viscous environments whilst P. gingivalis is nonmotile and highly proteolytic. Metabolically they co-operate and partition their environment to avoid competition. In this study we show that the motility of T. denticola is essential for synergistic polymicrobial biofilm development by these species which helps to explain their synergistic virulence in animal models and their intimate association during disease.