Nov. 2, 2000 ROLLA, Mo. -- In the wake of last month's announcement that scientists have found what they believe to be a living microbe that pre-dates Tyrannosaurus rex, Dr. Melanie Mormile is keeping one eye on salt crystals that contain ancient earth-bound bacteria and another on Mars.
Mormile, an assistant professor of biological sciences at the University of Missouri-Rolla and an expert on microscopic organisms, thinks living bacteria might be trapped in the sulphate and chloride salts of Mars. Her work is partially funded by NASA, which announced Oct. 26 that it has officially scheduled six robotic missions over the next ten years to hunt for signs of life on the red planet.
Meanwhile, at UMR, Mormile is in the process of conducting further research on salt crystals that contain trapped bacteria in an attempt to lend confirmation to an amazing report published in the October issue of the journal Nature.
One of Mormile's research peers, Dr. Russell Vreeland of West Chester University, is the co-author of the October Nature article, which announced the discovery of what Vreeland and his research group say is a 250-million-year-old microbe found in New Mexico salt deposits. The microbe, which is similar if not identical to a modern strain of bacteria, would be by far the oldest sample of a living bacterium ever found.
"Ideally, we'd like to find really ancient bacteria that have never been described before," says Mormile, who studies samples at UMR and confirms any exceptional findings through independent DNA testing. "That would help to rule out the possibility of contamination."
In order to date salt-loving bacteria on Earth, the age of the salt deposits must first be determined. By looking at individual salt crystals under a microscope, scientists are then able to find bacteria that are trapped in tiny bubbles. The trapped bacteria can be dated according to the age of the crystals.
Mormile's UMR lab is equipped with a special inverted microscope and micromanipulator. As a postdoctoral fellow at the Pacific Northwest National Lab in Washington, Mormile and her colleagues isolated a 97,000-year-old bacterium from salt crystals using this instrumentation.
"It's a little bit like "Jurassic Park,'" says Mormile, who notes that a 250- million-year-old bacterium finding pre-dates Jurassic dinosaurs by 20 million years or so. "In the book and the movie, scientists find a prehistoric mosquito trapped in amber. We're doing something similar with the bacteria that is trapped in salt crystals. And we hope to do this with Mars samples as well."
Although Mormile concedes it's possible that a modern bacterium was somehow introduced to the 250-million-year-old salt crystal discussed in the Nature study, thereby contaminating it, she remains optimistic that researchers will continue to find other bacteria from a similar time period. Such confirmation is necessary to prove that bacteria can live for hundreds of millions of years on Earth, a conclusion that would make life on Mars all the more plausible.
Scientists already know that bacteria can live without light or oxygen. They can thrive in boiling water or below the Arctic ice. Existing bacteria have been found in radioactive waste and, interestingly enough, in the belly of a bee trapped in amber for more than 25 million years.
If bacteria can survive under these conditions for so long, Mormile says, there is no reason to believe they can't exist in Mars' harsh environments, especially under its surface.
"I think there's a pretty good chance we'll find life on Mars," Mormile says. "Even though bacteria are not as fascinating to most people as aliens with big eyes, I think we could be in for some astounding discoveries."
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