When researchers began sequencing DNA from environmental samples more than a decade ago, they discovered a vast, diverse world of microbes. But this microbial dark matter has defied further description-and definitive placement on the tree of life-because so few kinds will grow in the lab. That didn't stop microbiologist Tanja Woyke from the Department of Energy Joint Genome Institute in Walnut Creek, California. She and her colleagues used an approach that allowed them to sequence the DNA in individual cells (rather than requiring many copies of the cells). They characterized 200 new microbes from 29 largely uncharted phyla, then used the genomes to determine the microbes' phylogenetic relationships and to assess how each lives, naming 18 phyla accordingly, the team reported online this week in Nature.
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