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"By reading the information stored in the genomes of entire microbial communities, we can begin to measure the pulse of this marine ecosystem," said MIT's Ed DeLong, who led the research team. "These new DNA sequences from microbial communities will help us paint the picture of how that world works and provide important details on the players involved and their biological properties and activities."

DeLong and his coworkers report their findings in the Jan. 27 issue of the journal Science.

The interdisciplinary research team sequenced a total of 64 million base pairs, or subunits, of DNA from microbes and viruses they collected at each depth. In the process, they discovered thousands of new genes from novel and ecologically abundant microbes and found evidence of frequent gene exchange between organisms. The study also revealed variations in genetic composition at different depths--including differences among genes involved with carbon and energy metabolism.

"Although they're small, these tiny microbial species are the engines of the biosphere, and in large part drive the cycles of matter and energy in the sea," said DeLong.

Microbes near the ocean surface, for example, had more genes devoted to taking in iron, a major element necessary for growth in that zone. Genomes from organisms below the ocean's deepest and darkest layers displayed almost epidemic levels of DNA associated with "jumping genes," or pieces of DNA that can move from one part of the genome to another.

Microbial ecologists have had fairly rudimentary tools and techniques to bring to bear on their research to date, DeLong said. But now with the ability to sequence vast amounts of DNA i
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Source:National Center for Atmospheric Research/University Corporation for Atmospheric Research