Metagenomics (also referred to as environmental and community genomics) is the genomic
analysis of microorganisms by direct extraction and cloning of DNA from an assemblage of
microorganisms. The development of metagenomics stemmed from the ineluctable evidence
that as-yet-uncultured microorganisms represent the vast majority of organisms in most
environments on earth. This evidence was derived from analyses of 16S rRNA gene
sequences amplified directly from the environment, an approach that avoided the bias …

I am grateful to Tom Lessie, Jill Banfield, and all of the members of my laboratory for
reviewing the manuscript; Christina Matta for assistance with historical research and
manuscript preparation; Carol Dizack for artistic contributions; C. Dizack and WI Welker for
the photograph of Yellowstone in Fig. 3; and Jill Banfield, Brett Baker, and Gene Tyson for
Fig. 2 and 7.