Combined, these “”exclusive”" sequences contributed to 11 – 20% of the total count of reads within an individual microbiome. Within an individual, one to six “”exclusive”" sequences were highly abundant (Table 3). Sequencing of a larger number of individual microbiomes is necessary for assessing the true exclusivity of these abundant individual-specific sequences. Table 3 Relative abundance of individual-specific (“”exclusive”") sequences Individual % Sequences “”Exclusive”" % of Reads with “”Exclusive”"

Sequences Taxonomy of Predominant “”Exclusive”" Sequencesa % of Reads Nr of Samplesb S1 19 20 Firmicutes;Bacilli;Lactobacillales;Streptococcaceae;Streptococcus 4.4 3       Bacteria;Bacteroidetes;Bacteroidia;Bacteroidales

Screening Library 1.2 9       Bacteria;Proteobacteria;Gammaproteobacteria;Pasteurellales;Pasteurellaceae 1.2 8       Bacteria;Proteobacteria;Gammaproteobacteria;Pasteurellales;Pasteurellaceae;Haemophilus 0.6 4       Bacteria;Proteobacteria;Gammaproteobacteria;Pasteurellales;Pasteurellaceae 0.6 5       Bacteria;Proteobacteria;Gammaproteobacteria;Cardiobacteriales;Cardiobacteriaceae;Cardiobacterium 0.5 4 S2 19 12 Bacteria;Proteobacteria;Betaproteobacteria;Neisseriales;Neisseriaceae;Neisseria 0.6 3 S3 17 11 Bacteria;TM7 0.7 3       Bacteria;Firmicutes;Bacilli;Bacillales;Staphylococcaceae;Gemella 0.5 7       Bacteria;Actinobacteria;Actinobacteria;Actinomycetales;Corynebacteriaceae;Corynebacterium STA-9090 datasheet 0.5 5 a – sequence was considered predominant if it contributed to at least 0.5% of the individual microbiome b – number Adenosine of samples of the particular individual where the respective “”exclusive”" sequence was found Phylotypes All three microbiomes shared 387 (47%) of 818 OTUs (Figure 3B). These overlapping phylotypes together contributed to 90 – 93% of each microbiome (Additional file 1). Fifty-one of these shared OTUs were abundant (≥0.1% of microbiome) and together occupied 62 – 73% of the individual microbiome (Figure 4). Figure 4 Shared abundant phylotypes in three oral microbiomes

and their relative abundance. Relative abundance of shared phylotypes within an individual microbiome. Only abundant phylotypes that contributed to at least 0.1% of the individual microbiome are shown. The most abundant phylotypes (≥0.5% of the microbiome) are grouped separately in the upper panel. Phylotypes were defined as OTUs clustering sequences at a 3% genetic difference. The highest taxon (in most cases, genus) at which the OTU was identified, is shown together with the cluster identification number. The full list of OTUs is available in Additional file 1. Different colours indicate three different microbiomes, S1, S2 and S3, respectively. Sixty-nine, 43 and 91 OTUs originated from one particular microbiome and contributed to 3.9%, 0.5% and 0.9% of the microbiome from individual S1, S2 and S3, respectively.