Fig. 1.

Diversity in the human microbiome. The human microbiome is dominated by four phyla: Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria. In the center is a phylogenetic tree of organisms abundant in the human microbiome. Commensal microbes are indicated by circles, and potential pathogens are indicated by stars. The middle ring corresponds to body sites at which various taxa are abundant and is color-coded by site [e.g., Ruminococcus (blue) is found mostly in the gut, whereas Lactobacillus (purple) is found mostly in the vagina]. Bar heights on the outside of the circle are proportional to taxa abundance at the body site of greatest prevalence [e.g., Streptococcus mitis (yellow) dominates the inside of the cheek, whereas the gut is abundant in a variety of Bacteroides]. The intensity of external colors corresponds to species prevalence in each body site (adapted with permission from [12])