As before, an OTU is considered to be shared if it is found in at least one member of each of the two species/groups compared. The highest amount of OTU-sharing is indeed between chimpanzees and bonobos (18.0%) and DRC and SL humans (24.2%), with less OTU-sharing between any ape and any human group (7.8 – 18.0%). The chimpanzees do share more OTUs with the SL humans at the same sanctuary (13.8%)

than with the DRC humans at the bonobo sanctuary (7.8%), which could indicate a greater influence of environment/contact in this case. However, the bonobos and DRC humans share 13.7% of their OTUs, selleck kinase inhibitor which is actually less than the fraction of OTUs (18.0%) shared between bonobos and SL humans. Overall these results do not make a compelling case for a major influence of environment/contact on the saliva microbiomes

of human workers and apes at the same sanctuary. We also investigated this issue with respect to the zoo apes, as here we have different species living in close proximity. As shown in Additional file 5: Table S4, there is on average higher OTU-sharing between the various pairs of zoo apes than between apes and humans in the sanctuaries: the average OTU-sharing between species is 20.6% for the zoo apes vs. 13.8% between PD-332991 apes and human workers at the same sanctuary. Thus, the zoo environment does appear to have significantly enhanced the sharing of OTUs among the different ape species. Discussion and conclusions We selleck provide here the first comparative analysis of the saliva microbiome of bonobos, chimpanzees and humans. We find greater similarity

in the composition of the saliva microbiome between bonobos and chimpanzees, and between human workers at the same sanctuaries. These results suggest that internal factors, related to phylogeny or host physiology, have a more important influence on the saliva microbiome than does geography or local environment. Phylogeny (i.e., vertical transmission of the microbiome) has been previously implicated in an analysis of the fecal microbiome from wild apes [9] and is in keeping with mother-child and twin studies of the oral microbiome that found a greater role for vertical than horizontal transmission [23, 24]. However, a recent study of mothers and infants found a higher correlation among the microbiomes of infants and of mothers than of infants with their mothers [25], suggesting that diet related aspects of host APR-246 physiology may also play a role. Our results are compatible with either phylogeny or dietary factors related to host physiology (e.g., proportion of meat in the diet) – or both – as the primary influence(s) on the saliva microbiome.