1% of the microbiome). One phylotype

(OTU ID 774, Pasteurellaceae) contributed to 2.2% of this microbiome and was preferentially found around the molar tooth (buccal, lingual and approximal surfaces of tooth 16) and in the sample obtained at the hard palate. The OTUs representing different phyla were not equally shared among the individuals (Table 2). The lowest similarity was observed in Spirochaetes (25% common OTUs), followed by Bacteroidetes and Cyanobacteria (33%), Proteobacteria (42%), Actinobacteria (48%), candidate division TM7 (50%), Firmicutes (57%), while the highest similarity was found in Fusobacteria (62%). The low similarity among the OTUs of Spirochaetes among the three microbiomes could be due to low abundance of this phylum in the different click here samples. Since a high prevalence of Spirochaetes in dental plaque is associated with periodontal disease [17], it would be interesting to assess the degree of similarity and diversity of these phylotypes in a group of periodontitis Pifithrin-�� patients. Higher taxa At the higher taxonomic levels, 72% of all taxa (genus level or above) were

shared by the three microbiomes, contributing to 99.8% of all reads. Only 2-11% of higher taxa were individual-specific (Figure 3C, Additional file 4). However, these taxa were found at a very low abundance (5-49 reads) and most likely were not a part of the commensal oral flora, and should be regarded as “”transients”". The observed overlap in taxa and in phylotypes is unexpectedly high and considerably higher than the recently reported average of 13% similarity in phylotypes between any two hands from unrelated individuals [12]. Of even greater contrast to our findings are the comparisons of gut microbiomes which show no overlap in microbiota 2-hydroxyphytanoyl-CoA lyase in unrelated individuals [1]. Instead of a core microbiome at an organismal lineage level, gut microbiomes

harboured distinct core genes [1]. The most probable explanation in the observed exclusiveness of gut microbiomes is the close interplay of intestinal microbiota with the host. In the abovementioned study on hand surface microbiomes, only five phylotypes were shared across the 102 hands sampled [12]. Human palms are continuously exposed to diverse biological and abiotic surfaces that may function as a microbial source, and furthermore, hands are regularly washed, allowing new communities of different origins to establish. This may explain the high diversity and relatively low overlap in hand palm communities. The situation is cardinally different in the oral cavity. Even though dental hygiene procedures (toothbrushing, flossing) effectively removes dental plaque, newly cleaned surfaces are continuously bathed in saliva.