The role of Porphyromonas gingivalis proteinases in synergistic interactions with Treponema denticola

In the human oral cavity Porphyromonas gingivalis and Treponema denticola dominated biofilm communities growing on the tooth root are associated with the progression and severity of the chronic inflammatory disease periodontitis. We show that these two phylogenetically distant bacteria co-operate to obtain maximum nutrition from host proteins and identify bacterial proteinases that are involved in these processes. We demonstrate that these species also avoid direct competition by partitioning environmental resources through modulation of gene expression, especially those genes encoding metabolic pathways. These processes give these two bacterial species an ecological advantage over other oral bacteria, enabling them to proliferate and cause damage to the host under specific environmental conditions.