Tracing the accumulation of in vivo human oral microbiota elucidates microbial community dynamics at the gateway to the GI tract

With great interest we read the article by Gaiser et al 1 that enrichment of oral bacterial taxa in pancreatic cancer highlights the role of oral microbiota. Not coincidentally, the presence of Fusobacterium nucleatum in paired saliva and colon samples of the patients with colorectal cancer has been reported,2 3 raising interest in whether disease starts in the mouth or in the intestine.4–6 Another reason people are interested in oral microbes is their potentials serving as biomarkers for systemic diseases.3 7–9 In this study, we examined how long the collapsed bacterial community can recover to its initial state when suffering from disturbance and whether oral microbes have sufficient robustness to serve as biomarkers. We longitudinally tracked the re-assembling process of human oral biofilms after clinical scaling. Paired saliva and dental plaque samples were collected from nine subjects at 11 time points (figure 1A and online supplementary figure S1). The 16S rRNA V3–V4 regions of 169 samples were amplified and sequenced, and the generated reads were analysed using QIIME.10 ### Supplementary data [gutjnl-2019-318977supp001.pdf] Figure 1 Longitudinal dynamics of in vivo human oral microbiota. (A) Overview of the study design and sample collection. (B) The alpha diversity of the dental plaque and salivary microbiota over time. The shadow around the line shows a 95% CI. (C) The Bray-Curtis distance calculated at the operational taxonomic unit (OTU) level across individual microbiota of the same time point. (D–E) The Bray-Curtis distance between microbiota of each time point and pre . Significance was measured using …