*3.3. Oral-Microbiome Structure*

Figure 1 shows the relative abundance of detected bacteria. Data are presented separately on the (A) phylum and (B) genus levels. The Firmicutes phylum was most abundant, followed by Actinobacteria and Bacteroides. The abundance of these phyla constituted 92.6% of the sample. On the genus level, *Streptococcus* represented 44.5%, *Rothia* represented 15.2%, and *Veillonella* represented 9.0% of the sample. The composition bar plots for each sample on the phylum level are shown in Figure S3 (Supplementary Materials). The proportional ranges of these bacteria were 42.7% to 93.0% for Firmicutes, 4.7% to 39.8% for Actinobacteria, and <0.01% to 39.6% for Bacteroides. Taxon prevalence is shown in Figure 2. The prevalence of each species is plotted against their abundance. Highly prevalent phyla were Firmicutes and Actinobacteria. The core line plot is shown in Figure S4 (Supplementary Materials).

**Figure 1.** Microbiome structure in saliva: (**A**) phylum level; (**B**) genus level.

**Figure 2.** Overview of operational-taxonomic-unit (OTU) prevalence and taxonomic affiliations.
