[meteorite-list] Underground Bacteria

From: Pete Pete <rsvp321_at_meteoritecentral.com>
Date: Thu Oct 26 08:06:58 2006
Message-ID: <BAY104-F301E43E76E3679DD7DEE5CF8070_at_phx.gbl>

Apologies if this was posted earlier - I may have missed it.



http://www.princeton.edu/main/news/archive/S16/13/72E53/index.xml?section=newsreleases

Abstract

Long-Term Sustainability of a High-Energy, Low-Diversity Crustal Biome

By Li-Hung Lin, Pei-Ling Wang, Douglas Rumble, Johanna Lippmann-Pipke, Erik
Boice, Lisa M. Pratt, Barbara Sherwood Lollar, Eoin L. Brodie, Terry C.
Hazen, Gary L. Andersen, Todd Z. DeSantis, Duane P. Moser, Dave Kershaw, and
T. C. Onstott

Geochemical, microbiological, and molecular analyses of alkaline saline
groundwater at 2.8 kilometers depth in Archaean metabasalt revealed a
microbial biome dominated by a single phylotype affiliated with thermophilic
sulfate reducers belonging to Firmicutes. These sulfate reducers were
sustained by geologically produced sulfate and hydrogen at concentrations
sufficient to maintain activities for millions of years with no apparent
reliance on photosynthetically derived substrates.


News Releases
All News Releases | « Previous News Release | Next News Release » For
immediate release: October 20, 2006
Media contact: Chad Boutin, (609) 258-5729, cboutin_at_princeton.edu
Two miles underground, strange bacteria are found thriving
A Princeton-led research group has discovered an isolated community of
bacteria nearly two miles underground that derives all of its energy from
the decay of radioactive rocks rather than from sunlight. According to
members of the team, the finding suggests life might exist in similarly
extreme conditions even on other worlds.

The self-sustaining bacterial community, which thrives in nutrient-rich
groundwater found near a South African gold mine, has been isolated from the
Earth's surface for several million years. It represents the first group of
microbes known to depend exclusively on geologically produced hydrogen and
sulfur compounds for nourishment. The extreme conditions under which the
bacteria live bear a resemblance to those of early Earth, potentially
offering insights into the nature of organisms that lived long before our
planet had an oxygen atmosphere.

The scientists, who hail from nine collaborating institutions, had to burrow
2.8 kilometers beneath our world's surface to find these unusual microbes,
leading the scientists to their speculations that life could exist in
similar circumstances elsewhere in the solar system.

"What really gets my juices flowing is the possibility of life below the
surface of Mars," said Tullis Onstott, a Princeton University professor of
geosciences and leader of the research team. "These bacteria have been cut
off from the surface of the Earth for many millions of years, but have
thrived in conditions most organisms would consider to be inhospitable to
life. Could these bacterial communities sustain themselves no matter what
happened on the surface? If so, it raises the possibility that organisms
could survive even on planets whose surfaces have long since become
lifeless."

Onstott's team published its results in the Oct. 20 issue of the journal
Science. The research group includes first author Li-Hung Lin, who performed
many of the analyses as a doctoral student at Princeton and then as a
postdoctoral researcher at the Carnegie Institution.

"These bacteria are truly unique, in the purest sense of the word," said
Lin, now at National Taiwan University. "We know how isolated the bacteria
have been because analyses of the water that they live in showed that it's
very old and hasn't been diluted by surface water. In addition, we found
that the hydrocarbons in the environment did not come from living organisms,
as is usual, and that the source of the hydrogen needed for their
respiration comes from the decomposition of water by radioactive decay of
uranium, thorium and potassium."


Because the groundwater the team sampled to find the bacteria comes from
several different sources, it remains difficult to determine specifically
how long the bacteria have been isolated. The team estimates the time frame
to be somewhere between three and 25 million years, implying that living
things are even more adaptable than once thought.

"We know surprisingly little about the origin, evolution and limits for life
on Earth," said biogeochemist Lisa Pratt, who led Indiana University
Bloomington's contribution to the project. "Scientists are just beginning to
study the diverse organisms living in the deepest parts of the ocean, and
the rocky crust on Earth is virtually unexplored at depths more than half a
kilometer below the surface. The organisms we describe in this paper live in
a completely different world than the one we know at the surface."

That subterranean world, Onstott said, is a lightless pool of hot,
pressurized salt water that stinks of sulfur and noxious gases humans would
find unbreathable. But the newly discovered bacteria, which are distantly
related to the Firmicutes division of microbes that exist near undersea
hydrothermal vents, flourish there.

"The radiation allows for the production of lots of sulfur compounds that
these bacteria can use as a high-energy source of food," Onstott said. "For
them, it's like eating potato chips."

But the arrival of the research team brought one substance into the
underground world that, though vital to human survival, proved fatal to the
microbes -- air from the surface.

"These critters seems to have a real problem with being exposed to oxygen,"
Onstott said. "We can't seem to keep them alive after we sample them. But
because this environment is so much like the early Earth, it gives us a
handle on what kind of creatures might have existed before we had an oxygen
atmosphere."

Onstott said that many hundreds of millions of years ago, some of the first
bacteria on the planet may have thrived in similar conditions, and that the
newly discovered microbes could shed light on research into the origins of
life on Earth.

"These bacteria are probably close to the base of the tree for the bacterial
domain of life," he said. "They might be genealogically quite ancient. To
find out, we will need to compare them to other organisms such as Firmicutes
and other such heat-loving creatures from deep sea vents or hot springs."

The research team is building a small laboratory 3.8 kilometers beneath the
surface in the Witwatersrand region of South Africa to conduct further study
of the newly discovered ecosystem, said Onstott, who hopes the findings will
be of use when future space probes are sent to seek life on other planets.

"A big question for me is, how do these creatures sustain themselves?"
Onstott said. "Has this one strain of bacteria evolved to possess all the
characteristics it needs to survive on its own, or are they working with
other species of bacteria? I'm sure they will have more surprises for us,
and they may show us one day how and where to look for microbes elsewhere."

Other authors of this work include Johanna Lipmann-Pipke of
GeoForschungsZentrum, Potsdam, Germany; Erik Boice of Indiana University;
Barbara Sherwood Lollar of the University of Toronto; Eoin L. Brodie, Terry
C. Hazen, Gary L. Andersen and Todd Z. DeSantis of Lawrence Berkeley
National Laboratory, Berkeley, Calif.; Duane P. Moser of the Desert Research
Institute, Las Vegas; and Dave Kershaw of the Mponeng Mine, Anglo Gold,
Johannesburg, South Africa.

Pratt and Onstott have collaborated for years as part of the
Indiana-Princeton-Tennessee Astrobiology Institute (IPTAI), a NASA-funded
research center focused on designing instruments and probes for life
detection in rocks and deep groundwater on Earth during planning for
subsurface exploration of Mars. IPTAI's recommendations to NASA will draw on
findings discussed in the Science report.

This work was also supported by grants from the National Science Foundation,
the U.S. Department of Energy, the National Science Council of Taiwan, the
Natural Sciences and Engineering Research Council of Canada, Deutsche
Forschungsgemeinschaft (DFG, German Research Foundation) and the Killam
Fellowships Program.

More information about the discovery can be found at
http://newsinfo.iu.edu/news/page/normal/4229.html and
http://www.carnegieinstitution.org/news_releases/news_2006_1019.html




http://www.princeton.edu/main/news/archive/S16/13/72E53/index.xml?section=newsreleases

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Received on Thu 26 Oct 2006 08:06:50 AM PDT