Ancient Bacteria Brought Back to Life
Wednesday, October 18, 2000
Science fiction became science fact recently when researchers revived ancient bacteria that has survived for millions of years.
Nestled in a salt crystal, fossil and radiation tests show that the bacteria predates the dinosaurs and was able to survive the global changes that wiped them out.
"The idea of having a living glimpse of what life looked like 250 million years ago is pretty spectacular." said Paul Renne, a geologist at the University of California at Berkeley.
Researchers believe that the discovery could create a new image of the prehistoric world if testing shows its the real thing. The oldest living organism ever recorded could also highlight how life can exist under the most extreme conditions.
DNA tests have show that the bacterium is related to the modern Bacillus, which is found in soil, water and dust. Further study of its genetic makeup can help scientists fine-tune the evolutionary timetable for the organism and its modern counterparts, said Russell Vreeland, a biologist at Pennsylvania's West Chester University and co-author of the study that appears in Thursday's issue of the journal Nature.
The bacteria was found in a fluid-filled bubble inside a salt crystal 1,850 feet underground, about 30 miles east of Carlsbad, N.M. The area was a vast barren salt lake at the end of the Paleozoic Era, when the world was in the middle of a mass extinction.
"The end of the Paleozoic was such a curious time and we don't really know what happened," said Renne, who was not involved in the research. "This offers the possibility that we may be able to interrogate some of the organisms that were around."
The researchers are confident that the germ has been locked away in the crystal all these years. They are also convinced that it poses no threat.
"We all feel reasonably comfortable that this particular organism isn't going to attack anything," Vreeland said.
Still, there is the possibility the bacteria somehow seeped into the salt more recently in small drops of water, said Chris McKay, a biologist at NASA's Ames Research Center.
"Unlike amber or rocks or permafrost, salt is not an impermeable material," he said.
The scientists pulled about 220 pounds of rock salt from the Waste Isolation Pilot Plant, an underground nuclear waste dump. Fifty-six crystals that showed no signs of contamination were sampled for the presence of bacteria.
One crystal the size of a large postage stamp contained the organism. Two other strains of bacteria were found and are being studied.
The scientists took pains to prevent contamination by testing the sample in a containment lab in Pennsylvania.
They believe the bacteria survived as a spore, which are well-known for their longevity, and metabolized very little or not at all over the years. In the past, spores have been found in a 118-year-old can of meat, and yeast has been cultured from a 166-year-old bottle of porter ale, R. John Parkes of England's University of Bristol said in a Nature commentary.
In 1995, researchers at California Polytechnic State University reported reviving Bacillus bacteria spores from the stomach of a 25 to 30 million year old amber-encased bee.
Since 1960, researchers have reported finding organisms up to 650 million years old in salt, but the findings were met with skepticism because of contamination fears.
In any case, the latest study shows that life can exist inside a salt crystal.
"So the next time you sprinkle salt on your food, think of what else you might be eating," Parkes said.
— The Associated Press contributed to this report.
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