FIG 1.

Graphical representation of data adapted from the work by Lloyd et al. (7) showing the proportion of uncultured cells from Earth’s habitats, with an inset demonstrating that culturability is highest for humans and human-associated environments. Based on the conservative simplification of a single 16S rRNA gene per genome, Lloyd and colleagues estimate that 19% of Earth’s microbial cells are from cultivated lineages (pink). The remaining 81% are cells from uncultured genera or higher levels of taxa, with 25% from uncultured phyla (cream). In contrast, microbial populations from humans are overwhelmingly from cultured genera, with only ∼1% of cells belonging to uncultured phyla. (Image generated from the R package “maps” and royalty-free clipart.)