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Buried ecosystems excite scientists

AFP-JIJI

Diverse underground ecosystems buried deep beneath the Earth’s crust may offer clues to the origins of life on Earth, several recent studies have revealed.

Whether it is tiny worms found wriggling in the depths of a South African mine or micro- organisms discovered 6 km under the surface in China, subterranean life-forms are found everywhere.

“We are making incredible discoveries about the nature and distribution of deep microbial life,” said Robert Hazen, executive director of the Carnegie Institution’s Deep Carbon Observatory geophysical laboratory.

“If you are near the surface, from a few centimeters to many kilometers, there is microbial life anywhere you go.

“You drill deep holes, you bring up the core and there are microbes living in the rocks.”

Hazen said that microbes have been found in rocks that were recovered by drilling over 6 km beneath the surface in China’s Songliao basin, and that tiny worms have been found in fractures in rocks lying 1.3 km deep in a South African mine.

The Deep Carbon Observatory was set up to analyze the amounts, sources and movement of carbon within Earth.

Scientists say microbes found in the oceanic crust and sediment layers lying below them could play an important role in microbial diversity by inserting themselves into the genome of microorganisms.

“It’s an intriguing part of evolution,” said John Baross, a professor at the University of Washington in Seattle.

“The deep subsurface may have acted as a natural laboratory for the origin of life in which multiple experiments could have been carried out in tandem,” he said.

“You have everything you need to make life, including energy, water and carbon-rich molecules that could have made the underground rather than the surface of the planet, the cradle of the very first life on Earth.

“We may find totally new kinds of life as we reach greater depths, higher temperatures and pressures. Quite possibly Earth’s deepest life doesn’t use DNA and proteins the way normal cells do.”

The variety of the bacteria, single-celled but unrelated archaea and even viruses existing in this dark realm has been described by scientists as an “underground Galapagos.”

Mark Lever, of the Center for Geomicrobiology at Aarhus University in Denmark, noted that microorganisms in the Earth’s crust use hydrogen to convert carbon dioxide into organic materials.

Although the vast ecosystem is probably based mainly on hydrogen, several different forms of life exist in this extreme environment, he added in a study published Friday in the journal Science.

Finding life in Earth’s most hostile environments could create a picture of life found on other planets, such as Mars.

Researchers at the University of Maryland studying microorganisms in a salt lake in Antarctica on behalf of the U.S. space agency NASA have found subtle variations in proteins from extremophile bacteria compared to those of ordinary microorganisms.

The variations could allow them to survive in environments such as Mars, notable for extreme temperatures and high salinity, according to a study published in the journal PLoS One.