Thriving Bacteria Colonies Found

.c The Associated Press

By PAUL RECER

WASHINGTON (AP) - In a discovery that suggests life is possible on Mars or on a frozen moon of Jupiter, researchers say they have found colonies of bacteria thriving inside blocks of solid ice in lakes near the South Pole.

A team of researchers drilling through the perpetual ice filling shallow lakes in Antarctica, found teeming communities of microbes living and thriving in temperatures that seldom rose above the freezing point of water.

``This is more proof that life is a lot more hardy than we once thought,'' said Brian D. Lanoli of Oregon State University in Corvallis, co-author of study being published Friday in the journal Science.

If microbes can thrive in such frigid, hostile surroundings as the Antarctic lakes, he said, then it could perhaps also be found in the frozen seas of Europa, a moon of Jupiter, or the ice caps of Mars.

``Since we know there is ice elsewhere in our solar system, this discovery makes us wonder if life might not exist there also,'' said Stephen J. Giovannoi, another co-author from Oregon State.

The researchers found the microbial colonies while drilling ice cores from six lakes in Antarctica. As they drilled, they discovered a layer of dust and grit down six to eight feet below the surface of the always-frozen lakes.

Giovannoi said the grains of soil set up a ``special set of circumstances'' that made it possible for the microbes to live.

He said the dust was blown onto the ice during the Antarctic summer during a time when the sun is always shining. The grains absorbed solar heat and slowly sank into the ice. They reached a point, about six to eight feet down, and stopped sinking. A pocket of water formed around them and it was here that the microbes set up their community.

The lakes are located in what is, in effect, a desert. The air is very dry and precipitation is very low. Ice on the surface of the ponds actually is eroded away continually. Water pockets remain, however, at the same relative position, some six to eight feet from the surface, and eight to 10 feet above the bottom of the lakes.

The lively time for the microbes lasts only while the sun shines. Some of the organisms make food through photosynthesis from the weak polar sun. But more than half of the year is spent in twilight or total darkness of the extreme Antarctic seasons.

``Their temperature, even when they are active, is about zero degrees Centigrade (32 degrees F),'' said Giovannoi. This is just at the freezing point of water.

In the winter, however, he said, the temperatures in the ice drops to minus 20 F or colder.

``They (the microbes) are frozen in most of the year,'' said Giovannoi. And, yet, he said, they have adapted to the extreme conditions and are thriving.

``What at first glance appears to be a contradiction in terms (being frozen and leading an active life at the same time) turns out to be an exciting example of the adaptation of microorganisms to environmental extremes,'' the authors write in Science.

The physics that set up the conditions to enable the microbes to live suggests that such environments could exist on Mars, which may have frozen polar caps, or on Europa, a Jovian moon known to be covered with frozen water, the researchers said.

It may be possible that in soil or sand grains embedded in ice on can absorb enough solar energy to thaw the ice and create watery pockets where microbes could survive, said Giovannoi.

This creates a whole new niche for microbial communities to thrive in, he said.

AP-NY-06-25-98 1653EDT