BOZEMAN, MT -- A team led by Montana State University biologist John Priscu has discovered bacteria in an ice core drilled from deep within a frozen Antarctic lake.
The bacteria came from Lake Vostok, a subglacial body of water the size of Lake Ontario resting more than two miles under the East Antarctic ice cap.
"From a biologist's perspective, this is the Holy Grail of lake biology," Priscu said before leaving Montana for another field season on the frozen continent. "Our findings indicate that the microbial world has few limits on our planet."
Priscu's team, along with two other groups studying Vostok ice, will publish its findings in the Dec. 10 issue of the journal Science.
The team includes seven MSU scientists plus scientists from the University of Alabama, the U.S. Geological Survey and the NASA Ames Research Center.
The Vostok ice is among the deepest ever explored for life, Priscu said, and could be a model for searching for life in frozen environments elsewhere in the solar system.
"You don't have to leave the planet to study this completely unexplored system, but the samples sure aren't easy to get," Priscu said of the Vostok core, drilled by Russian scientists and distributed through the National Science Foundation.
The clear ice core, 18 inches long and 4 inches wide, was plucked from 3,590 meters (about 11,800 feet) below the surface of the ice sheet and about 150 meters (495 feet) above Lake Vostok. Discovered in 1974, the lake is one of the world's ten deepest bodies of water and one of about 70 lakes underneath the glaciers of central Antarctica.
The bacteria, commonly associated with soils, are related to microbes called proteobacteria and actinomycetes. They could have been blown on bits of soil from the Patagonian deserts onto the East Antarctic ice sheet and then buried, Priscu said. If so, the microbes could be more than half a million years old.
Another possibility is the microbes originated in the lake and became trapped as lake water refroze or accreted to the bottom of the overlying glacier, he said.
In either case, the study suggests the lake could support a microbial population, despite a million years of isolation from the atmosphere, according to the article in Science.
The MSU-led group was not able to determine whether the microbes were alive or merely trapped in an ancient icy grave.
"They could have been alive, but growing so slowly that we could not detect growth rates using our protocols," Priscu said. "If alive, I think they are in a maintenance mode of metabolism, rather than one of active growth."
Priscu and his teams have found microbes growing in other Antarctic frozen lakes, but none nearly as deep as Lake Vostok. Microbes are known to hang out in other extreme environments, such as hot vents along undersea trenches, deep in the earth's subsurface and in geothermal pools like those in Yellowstone National Park.
And if microbes exist on other planets, such as in the frozen ocean thought to exist on Jupiter's moon Europa, finding them could be similar to hunting for them in Lake Vostok, the scientists say.
"Similar to Lake Vostok accretion ice, this ice may retain evidence for life, if present, in the europan ocean," the scientists wrote.
Internal energy from the planet could drive an ice system independent of the sun and possibly sustain life in really extreme environments, said MSU earth sciences professor and co-author David Mogk.
"I think the message is really, 'Life is where you find it'," Mogk said. "If you find it under nearly 4,000 meters of ice, I mean, that's pretty staggering."
In addition to searching for bacteria, the group studied the ice's unique crystal structure and mineral composition using aspecialized scanning electron microscope.
They saw parts of only two large crystals in the sample. The crystals weren't oriented vertically as you would expect in a quiet lake, said MSU civil engineering professor Ed Adams. He'd have to analyze more samples to understand why but suspects sheer stresses could play a role in crystal misalignment. Another possibility is that ice crystals initially nucleate in the lake water and attach to the overlying ice at a random orientation.
Adams said the group hopes to get more core samples from the National Science Foundation, which paid for the research along with MSU.
Other MSU scientists who helped with the project are Bob Brown, Cristina Takacs, Craig Wolf and Recep Avci. Additional coauthors are W. Berry Lyons and Kathy Welch from the University of Alabama; Mary Voytek and Julie Kirshtein from the U.S. Geological Survey and Christopher McKay, Space Sciences Division, NASA Ames Research Center.
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