Thursday, April 16, 2009

Bacteria thriving beneath Antarctic glacier

Scientists have uncovered an ancient ecosystem below an Antarctic glacier that survived millions of years in cold brine without light or oxygen, a study said.
Because the ecosystem was isolated for so long in extreme conditions, it could shed light on possible extraterrestrial life and how systems can survive under ice, said longtime Antarctic researcher and Montana State University professor John Priscu, a co-author of the study.
The Antarctic ecosystem contained bacteria that thrive in cold, salty water and survived by transforming sulfur and ion compounds for growth, according to the study published in Friday's edition of Science.

The pool of brine, trapped below Taylor Glacier and next to frozen Lake Bonney in eastern Antarctica, averaged 14 degrees Fahrenheit (negative 10 degrees Celsius). But it did not freeze because the water was three or four times saltier than the ocean.

The ecosystem has the "potential to be a modern analog to what geochemistry and biogeochemistry was like millions of years ago," said Jill Mikucki, the study's lead author.

Large ice sheets covered the planet during the "Snowball Earth" period.

The researchers used biogeochemistry, microbiology and molecular biology techniques to determine how the ecosystem could survive without photosynthesis.

They found the bacteria when investigating Blood Falls, blood-red waters that flow from Taylor Glacier. The falls owe their red color to an iron-rich pool, according to the scientists.

The most common bacteria in the brine pool was the Thiomicrospira arctica. Estimated at less than three miles (4.8 kilometers) wide, the pool is believed to be a remnant of an ancient ocean trapped at least 1.5 million years ago when Taylor Glacier displaced Lake Bonney.

Priscu said the researchers could not reach the pool because it lies too far away -- about 2.5 miles (4 kilometers) -- from the snout of the glacier, itself too thick to drill.

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