A "weird" community of microbes living in a hot, acidic geyser in Wyoming's Yellowstone Park may help scientists know what to look for in seeking life on Mars and elsewhere in space, researchers said Wednesday.
They found the new species of algae and bacteria living in a green-colored layer of sandstone in Yellowstone's Norris Geyser Basin. It was not a place where one would normally expect to find life thriving, said biologist Norman Pace of the University of Colorado at Boulder's Center for Astrobiology.
"The pores in the rocks where these creatures live has a pH value of one, which dissolves nails," Pace said in a statement. "This is another example that life can be robust in an environment most humans view as inhospitable."
The microbes seemed to fossilize well, and perhaps researchers could compare their fossils to rocks from Mars and elsewhere to see how much they resemble one another.
One asteroid from Mars found in Antarctica is being studied extensively to see if it carries fossilized remnants of tiny bacteria.
"Remnants of these communities could serve as 'biosignatures' and provide important clues about ancient life associated with geothermal environments on Earth or elsewhere in the solar system," the researchers wrote in their report, published in the journal Nature.
Rich in acid, metals and silicates
The waters of Norris Geyser Basin, one of the hottest in the world, are rich in sulfuric acid, metals and silicates.
Similar kinds of geothermal environments may once have existed on Mars. Robotic rovers are searching the planet's surface for evidence of them.
"This is the first description of these microbial communities, which may be a good diagnostic indicator of past life on Mars because of their potential for fossil preservation," said Jeffrey Walker, who helped write the study.
"The prevalence of this type of microbial life in Yellowstone means that Martian rocks associated with former hydrothermal systems may be the best hope for finding evidence of past life there," he said.
'Eureka' moment
Walker said he found the new microbe community in 2003 after breaking apart a chunk of sandstonelike rock.
"I immediately noticed a distinctive green band just beneath the surface," he said. "It was one of those 'eureka' moments."
Genetic analysis determined the green band was caused by a new species of photosynthetic Cyanidium algae.
Living among them were a new species of Mycobacterium, a group of microbes best known for causing human illnesses such as tuberculosis and leprosy, Walker said.
Other species of bacteria also living in the rock, and only a few were the "extremophile" species usually found in such environments, the researchers said.
Pace described the new life forms as "pretty weird."
"It may well be a new type of lichenlike symbiosis," said Pace, who won a MacArthur Fellowship, or "genius grant," in 2001. "It resembles a lichen, but instead of being comprised of a symbiosis between a fungus and an alga, it seems to be an association of the Mycobacterium with an alga."
