Sequencing the environment

Bacteria and archaea are ubiquitous in the environment, and have fundamental roles in the major geochemical cycles, in addition to being important in aspects of the growth of most multicellular eukaryotes, and in modifying human interactions with the environment. Although individual organisms with important roles in these processes can be identified, mixed communities of organisms that are often unculturable are usually involved. Two approaches to a genomic investigation of environmental communities can be envisaged; first, complete analysis of specific important organisms, and second, whole-community shotgun analysis of the entire community. Examples of both approaches are discussed this month.