TABLE 1

Metagenome-based estimates of global microbial cell abundances from uncultured archaea and bacteria, based on 16S rRNA gene sequence read depthsa

Environment
(reference)
No. (%) of microbial cells × 1026b
TotalCultured
species to
genera
Uncultured
genera to
classes
Uncultured
phyla and
higher
Marine sediment (48)2,900390 (13)1,921 (66)590 (20)
Soil (49)2,560454 (18)1,268 (50)839 (33)
Terrestrial subsurface (49)2,500702 (28)1,211 (48)587 (23)
Seawater (49)1,010143 (14)640 (63)229 (23)
Freshwater (49)1.30.1 (11)0.8 (64)0.3 (25)
Plant hosts (50)10.5 (49)0.4 (37)0.1 (14)
Animal hosts (51)0.20.1 (49)0.1 (37)0.0 (14)
Total8,9741,689 (19)5,050 (56)2,245 (25)
  • a Environments with fewer microbial cells were excluded.

  • b Cutoff values represent the upper 95% confidence interval of the median 16S rRNA gene identity for each taxonomic level (12).