A shallow aquifer beneath the Colorado River floodplain doesn’t spring to mind as a hotspot for new forms of life. But it turns out that the area, near the
town of Rifle, Colorado, is prime real estate for bacteria.
Nobody expected to see such a lively community until University of California, Berkeley, geomicrobiologist Jillian Banfield visited the site to sample the
water for genetic material. Given the unexpected biodiversity she and her colleagues uncovered there — and at other inhospitable sites, from Yellowstone
hot springs to Chile’s Atacama Desert — Banfield created a new Tree of Life.
Mapping the genetic relationship between species, the tree shows that scientists have been oblivious to nearly a third of life — mostly bacterial — on
Earth. That’s because approximately half the world’s bacteria cannot be cultivated in a lab. Banfield and her colleagues overcame the problem by analyzing
environments metagenomically: sequencing each community’s DNA and then puzzling together individual genomes.
A Tree of Life shows “how organisms are related to each other,” Banfield says, and the goal of this version, published in April in Nature Microbiology, was
“to provide a balanced sampling.” It’s a new view of life that accounts for diverse possibilities beyond what can grow in a petri dish.