Species-specific gene expression of the oral microbiota in health and diesease

The purpose of the present investigation was to use the oral cavity as an in-vivo model to study the impact of internal and external perturbations on bacterial biofilm communities. We tested the hypotheses that bacterial gene expression of the healthy microbiota reflects habituation to site-specific ecological perturbations, and that the perturbation effect of chronic inflammation, periodontitis, impacts bacterial gene expression not only locally, but also at other sites of the oral cavity. Oral microbial samples were collected from three oral sites plaque, tongue and saliva from patients with periodontitis and healthy controls. Paired metagenomics and metatranscriptomics were used to perform concomitant characterisation of taxonomic composition and to determine species specific bacterial activity as expressed by the ratio of messenger RNA to the corresponding genomic DNA.