National Science Foundation
Washington, D.C.
Media contact:
Peter West, (703) 306-1070, pwest@nsf.gov
Program contact:
Polly Penhale, (703) 306-1033, ppenhale@nsf.gov
Embargoed until 2 P.M. EST, December 9, 1999
NSF PR 99-72
Bacteria May Thrive in Antarctic Lake –
Holds Implications for Search for Life in the Solar System
Two separate investigations of ice drilled at Lake Vostok, a suspected
body of subglacial water deep in the Antarctic interior, indicate that
bacteria may live thousands of meters below the ice sheet. The findings
by two National Science Foundation-funded researchers are scheduled
for publication in the Dec. 10 issue of Science.
Two research teams, led by David M. Karl from the University of Hawaii
and John C. Priscu of Montana State University, examined fragments of
ice taken from roughly 3,600 meters (11,700 feet) below the surface —
about 120 meters (393 feet) above the interface of ice and suspected
water. Both teams found bacteria in “accreted” ice, or ice believed to
be refrozen lake water.
The teams conclude that a potentially large and diverse population of
bacteria may be present in the lake. If so, this bacteria answers an
intriguing scientific question about whether an extremely cold, dark
environment which is cut off from a ready supply of nutrients can
support life.
The DNA analysis by Priscu’s team indicates that although the bacteria
have been isolated for millions of years, they are biologically similar
to known organisms. “Our research shows us that the microbial world
has few limits on our planet,” said Priscu. He added that Lake Vostok
“is one of the last unexplored oases for life” on Earth.
The teams also conclude microbes could thrive in other, similarly
hostile, places in the solar system. Lake Vostok is thought to be an
analog to Europa, a frozen moon of Jupiter. Priscu notes in his paper
that the Galileo spacecraft found evidence that liquid water exists
under an icy crust on the Jovian moon. “Similar to ice above Lake
Vostok, this ice may retain evidence for any life, if present, in the
Europan ocean,” he writes.
Evidence from radar mapping and other sources indicates that under
several thousand meters of ice, liquid water may exist in Lake Vostok,
possibly warmed by the pressure of the ice above or by thermal
features below. The lake is roughly the size of Lake Ontario in North
America. Vostok Station — a Russian scientific outpost, which once
recorded the lowest temperature on earth (-126.9 degrees Fahrenheit/
-89.9 degrees celsius) — is located on the ice above the lake. As part
of a joint U.S., French and Russian research project, Russian teams
have drilled down into the ice covering the lake, producing the
world’s deepest ice core. Drilling was deliberately stopped to
prevent introducing materials that would contaminate the water.
Karl notes at least one outstanding question about Lake Vostok:
whether the ice in which the bacteria were found is sufficiently
similar to the water in the lake to allow scientists to conclude
that a similar population — or even larger, more diverse one —
might thrive in the suspected liquid water.
Delegates from several nations, including a U.S. delegation sponsored
by NSF, met in England last September to decide whether and how to
explore the suspected lake without contaminating it. No firm proposal
has yet been accepted to accomplish that. “We don’t know what’s
in Lake Vostok, and we may never know, if we don’t get the
contamination issues solved,” Karl said.
While the current findings may prove the existence of life in the lake,
there are other scientific reasons to explore the lake itself. Ice cores
have helped scientists assemble a climate record stretching back more
than 400,000 years. Sediment samples from the bottom of Lake Vostok
could extend that record to cover millions of years. “There are other,
compelling reasons to go into the lake,” Karl concluded.
