The purpose of the present investigation was to characterize species-specific bacterial activity of the oral microbiota in periodontitis. We tested the hypotheses that chronic inflammation, i.e., periodontitis, associates with bacterial gene expression of the oral microbiota. Oral microbial samples were collected from three oral sites—subgingival plaque, tongue, and saliva from patients with periodontitis and healthy controls. Paired metagenomics and metatranscriptomics were used to perform concomitant characterization of taxonomic composition and to determine species-specific bacterial activity as expressed by the ratio of specific messenger RNA reads to their corresponding genomic DNA reads. Here, we show the association of periodontitis with bacterial gene expression of the oral microbiota. While oral site was the main determinant of taxonomic composition as well as bacterial gene expression, periodontitis was significantly associated with a reduction of carbohydrate metabolism of the oral microbiota at three oral sites (subgingival plaque, tongue, and saliva). Data from the present study revealed the association of periodontitis with bacterial gene expression of the oral microbiota. Conditions of periodontitis was associated with bacterial activity of local subgingival plaque, but also on tongue and the salivary microbiota. Collectively, data suggest that periodontitis associates with impaired carbohydrate metabolism of the oral microbiota. Future longitudinal and interventional studies are warranted to evaluate the potential pathogenic role of impaired bacterial carbohydrate metabolism not only in periodontitis but also in other diseases with low-grade inflammation, such as type 2 diabetes mellitus.

本研究的目的是描述牙周炎中口腔微生物群的物种特异性细菌活性。我们检验了慢性炎症（即牙周炎）与口腔微生物群的细菌基因表达相关的假设。从牙周炎患者和健康对照者的三个口腔部位——龈下菌斑、舌头和唾液中收集口腔微生物样本。配对的宏基因组学和宏转录组学用于对分类组成进行伴随表征，并确定特定信使 RNA 读数与其相应基因组 DNA 读数的比率表示的物种特异性细菌活性。在这里，我们展示了牙周炎与口腔微生物群的细菌基因表达的关联。虽然口腔部位是分类组成和细菌基因表达的主要决定因素，但牙周炎与三个口腔部位（龈下菌斑、舌头和唾液）口腔微生物群的碳水化合物代谢减少显着相关。本研究的数据揭示了牙周炎与口腔微生物群的细菌基因表达之间的关联。牙周炎的状况与局部龈下菌斑的细菌活动有关，但也与舌头和唾液微生物群的细菌活动有关。总的来说，数据表明牙周炎与口腔微生物群的碳水化合物代谢受损有关。