Antarctica's "New Life": Expected, or Extraordinary?

Antarctica's Lake Vostok is buried 2 miles beneath a sheet of ice, where it's been isolated from the surface for more than 14 million years. No sunlight reaches the lake, organic matter is few and far between, and the temperatures go as low as 27 degrees Fahrenheit. For years, Russian scientists have been drilling toward the lake, hoping to find out whether life could exist in a place cut off from Earth's surface?and what that life would be like.

Last week, those scientists trumpeted that they had discovered "new life" in Lake Vostok. Sergey Bulat, a geneticist at the St. Petersburg Institute of Nuclear Physics and leader of the Russian team, told reporters that the team pulled a previously unknown form of bacteria from the borehole. Bulat's team contended that the bacteria shares only 86 percent of its DNA with known forms of life, representing a new species or previously unknown lineage of bacteria.

In the days since then, researchers have gone back and forth about whether the claims are correct. But even if they are, the finding might not be as remarkable as it sounds?not because it isn't cool to find life buried in an Antarctic lake, but because scientists are finding all the time that life thrives in weird places.

The Controversy

By Monday morning, Vladimir Korolev, the head of the St. Petersburg Institute of Nuclear Physics, told the Interfax news agency that the samples had been contaminated and there was no new life. But now it looks like the popular consensus will have to reverse positions again. In an email to Popular Mechanics, Bulat defended the original claim, saying, "Dr. Korolev is a head of our division and was completely unaware about our latest results?in fact he was never interested in this field and he was wrong person to contact for any comments on our work." (Korolev did not respond to multiple requests to confirm this statement.)

So it looks as if we have a new form of bacteria on our hands?maybe. The discovery needs to be confirmed in other samples, which Bulat says his team will collect during an expedition in mid-May. He hopes the mission will reveal other bacteria as well, "because we suppose that it's not just one species that can live in the lake, it should be an entire community."

Ariel Anbar, an astrobiologist from Arizona State University, says it's impossible to comment on the significance of the finding and what it may mean because the results have not been published in a peer-reviewed journal. "I'm left curious but wanting to see data."

A press release, translated from Russian via Google Translate, states that the bacteria's "similarity in DNA sequence with known taxa was less than 86 percent." It's not clear whether the researchers analyzed the entire genome of the bacteria, or just the sequence of one or a few genes. When it comes to comparing whole genomes, two bacteria may share only 70 percent of their DNA but still be considered members of the same species.

Meanwhile, if the researchers are comparing one gene only, then the 86 percent figure might be low but not unheard of, says Louisiana State University biologist Brent Christner. "Calling it new life is a bit of a stretch," Christner says. "He's using a DNA-based method, which is targeted to old life." Or in other words, it's not as if they've found an organism whose fundamental biochemistry is wildly different from life as we know it.

The Consequences

If the results hold up and the Vostok microbes turn out to be a new species or lineage of bacteria, it won't be an earth-shattering conclusion. In fact, biologists are finding microbes in pretty much every place they look these days. Late last year scientists discovered that more than 2000 types of bacteria can survive in the human belly button, and hundreds of those species appear to be new to science.

Life finds a way to survive even in the harshest environments. Recent studies have revealed that bacteria thrive in storm clouds many miles above the ground, as well as below ground under 2 miles or more of dirt. They lurk in the deepest parts of the ocean where the sun doesn't shine and in the salty sands of the Atacama, the driest desert in the world. Some can even thrive in water as caustic as battery acid.

So finding bacteria in Lake Vostok is in some ways "exactly what you would expect," Christner says. Just last month, he and a team of American scientists discovered microbes living in a different subglacial lake in Antarctica, Lake Whillans, though the team hasn't finished the genetic tests to determine whether these bacteria are new to science. Lake Whillans is much closer to the surface than Lake Vostok, but the results seem to indicate that life can indeed withstand the harsh conditions of Antarctica.

While the findings from lakes Whillans and Vostok might not reveal anything extraordinary about life on earth, they might aid the search for life on other worlds. The moons Europa (of Jupiter) and Enceladus (of Saturn) are favorites in the search for life, thanks to the oceans hiding beneath their shells of ice. Jupiter's Ganymede and Saturn's Titan may also harbor subsurface oceans. Microbes in Antarctica could provide scientists with a greater understanding of how life survives under such cold and dark conditions.

"If the 'unusual' species [in Lake Vostok] is proven to be a new species of bacterium, then it is a definite plus for astrobiology and the search for life," astrobiologist Louisa Preston from the Open University in the U.K., says. "If this is a new species, then it can be added to our database of extremophiles that might be found on other worlds, and if we are lucky may hold a few secrets as to its ability to survive in the lake."

Source: http://www.popularmechanics.com/science/health/breakthroughs/antarcticas-new-life-expected-or-extraordinary-15212355?src=rss

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