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2\14 Bugs from the deep may be window into the origins of life on earth and beyond
Part 1 of 2

American Association for the Advancement of Science 
Washington, D.C.

Contact:
Monica Amarelo, mamarelo{at}aaas.org 
Ginger Pinholster, gpinhols{at}aaas.org 

Prior to 13 February, 202-326-6440 
As of 13 February, 303-228-8301 

14 February 2003

Bugs from the deep may be window into the 
  origins of life -- on earth and beyond
=========================================

A world of new life forms thrives below ground, researchers say

Simple life forms are turning up in a surprising variety of 
below-ground environments, potentially making up 50 percent of the 
Earth's biomass, scientists said today at the American Association for 
the Advancement of Science (AAAS) Annual Meeting.

From South African gold mines, to cooled seafloor lavas, these 
subsurface bugs have provided clues to the potential for life on Mars, 
and the diversity of possible fuel sources for life, including nuclear 
energy and toxic waste.

Similar Environments on Mars

Life on Mars may exist in "pillow lavas," volcanic rocks that are 
common on and below the terrestrial seafloor, according to Martin Fisk 
of Oregon State University. He and his colleagues have investigated 
the bacteria that live inside pillow lavas on Earth, and found that 
the microbes seem to be getting their energy from reactions between 
the glass in the rock and water.

Pillow lavas are likely to exist on Mars, Fisk said, and their unusual 
bulbous shape should make them easy to detect as researchers increase 
the resolution of photos taken of the planet's surface.

"On Earth, microbes live in the glass of pillow lavas.  Mars could 
host life in similar volcanic rocks, although this would require the 
presence of 'primary producers' -- organisms that make organic matter 
from chemical energy and carbon dioxide," Fisk said. "We're currently 
working to identify those microbes in Earth's volcanic rocks."

Pillow lavas form as seawater rapidly cooled molten lava into volcanic 
glass. Because these glasses don't have internal crystal structures, 
the way minerals do, bacteria leave distinctively-shaped tracks as 
they bore minute holes into the glass.

"I sometimes joke that if NASA could get me a pillow lava, I could 
tell you if anything ever lived in it," Fisk said. He noted, however, 
that the rock would have to be well-preserved.

Life doesn't have to be from another planet in order to survive in 
seemingly inhospitable conditions, other speakers in the AAAS panel 
have discovered.

Getting in Deep

Tullis Onstott of Princeton University and his colleagues have found 
bacterial populations within the walls of South African diamond mines, 
at depths between 0.8 and 3.3 kilometers. There, temperatures reach up
to 60 degrees C and pressures are nearly 250 times as high as on the 
surface.

The microbes that Onstott and his colleagues have found are unlike any 
living near the Earth's surface. They may even be deriving their 
energy from nuclear power, at least indirectly.

Water plus nuclear radiation emitted from rocks, such as those in the 
mines produces hydrogen, oxygen, and hydrogen peroxide. The 
researchers have hypothesized that the bacteria may be using this 
hydrogen for fuel. 

"The deep subsurface may be the only place on Earth where communities 
are using nuclear power that is natural and environmentally safe," 
Onstott said.

The bacterial species may also be ancient. New age estimates from 
water samples taken from the mines suggest that the water is up to 100 
million years old.

"Studying these unusual, primitive microorganisms helps us appreciate 
life's ability to take hold in a remarkable variety of environments. 
It may even help us understand how life evolved on Earth or other
planets," Onstott said.

The Versatility of Life

Closer to home, Susan Brantley of Pennsylvania State University has 
grown bacteria on different mineral surfaces in her lab. Her goal is 
to understand how the microbes extract elements from their environment
to sustain themselves. 

"Early life had to solve all the same problems" that these bacteria 
do, Brantley said. She thinks that some bacteria's body chemistry may 
incorporate elements, such as nickel, that were most accessible when 
life emerged on Earth.

"Snapshots of the chemistry of the early Earth may be caught in these 
organisms," said Brantley.

Research in thermal hot springs also reveals bacteria's adaptability 
to all kinds of environments where photosynthesis cannot take place. 
Everett Shock of Arizona State University studies life in hot springs
such as those in Yellowstone National Park.

Shock and his colleagues have identified more than a hundred possible 
types of metabolic reactions in which the organisms derive their 
energy from chemical reactions. While these include familiar reactions
involving hydrogen, iron, sulfur, nitrogen, and organic compounds, 
they also involve more unusual elements, such as arsenic, selenium, 
and uranium.

Other metal-reducing bacteria may have potential for use in 
environmental cleanup efforts, according to John Zachara of the 
Pacific Northwest National Laboratory.

Another unsung role played by bacteria involves the formation of large 
deposits of methane hydrate on the seafloor. These deposits are solid 
under the high pressures and low temperatures at the seafloor. If that 
pressure were reduced or the temperature increased, however, the 
hydrate would likely vaporize, producing large volumes of methane, a 
potent greenhouse gas. Scientists have proposed that methane hydrates 
may have had a hand in past climate change episodes, or may be a 
possible fuel source. 

Frederick Colwell of the Idaho National Engineering and Environmental 
Laboratory has identified some of the microbes that make the methane 
in these deposits.  Colwell and his colleagues are now trying to 
determine the rate at which these bugs produce methane, which should 
help researchers predict where methane hydrates are located.

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