Microbes may have survived 250 million years in crystal

Thursday, October 19th 2000, 12:00 am
By: News On 6

Find suggests life can travel between planets

By Sue Goetinck Ambrose / The Dallas Morning News

The record for the planet's oldest living inhabitant has been broken, scientists say.

A new species of bacteria now claims top honors, new research suggests, after being buried alive in a crystal of salt in New Mexico for 250 million years, then revived in a Pennsylvania laboratory.

The tiny microbes smash the previous record, held by bacteria that survived in the gut of a bee entombed in amber for more than 25 million years.

Researchers say the new study, published in Thursday's issue of the scientific journal Nature, will be viewed with skepticism by some scientists. But if the bacteria really are 250 million years old, they lend new support to the idea that life can survive long enough to travel between Earth and other planets.

The ancient microbes also make it difficult to put a limit on how long life can survive, said Dr. William Rosenzweig, a microbiologist from West Chester University and an author of the new report.

"Assuming this organism has survived 250 million years, as long as it doesn't run into conditions that can harm it, I don't see any limit," Dr. Rosenzweig said. "I think this thing could have survived as long as it wanted to."

Dr. Rosenzweig and Russell Vreeland of West Chester, along with geologist Dennis Powers of Anthony, Texas, studied salt crystals buried more than 1,700 feet below the surface, in an air intake shaft of the Waste Isolation Pilot Plant in Carlsbad, N.M. Based on fossil and mineral evidence, scientists know the crystals formed 250 million years ago, when reptiles, amphibians and insects thrived on Earth and dinosaurs did not yet exist.

The salt crystals were carefully inspected to make sure they had not been damaged since their formation, allowing bacteria to sneak in more recently, Dr. Rosenzweig said. And the outsides of the crystals were treated with harsh chemicals to kill any modern bacteria that might have been contaminating the crystal surface.

With a tiny sterilized drill, the researchers withdrew droplets of fluid encased in the salt crystal. From the droplets, bacteria grew.

Genetic studies show the bacteria are a new species of Bacillus, the researchers found. Bacillus is one of the few types of bacteria able to form hardy spores (which are made up of the microbe and protective outer layers), said John Parkes, a microbiologist at the University of Bristol in England. Spore formation is the microbial equivalent of hibernation.

"If somebody had asked me about the prospects of even a spore lasting this long, I'd have said, 'No, I don't think so,'" he said. But, he added, "if anything is going to survive it's going to be a spore."

The results need to be confirmed by other scientists before they will be completely accepted, he said.

Dr. H. Jay Melosh, a planetary scientist at the University of Arizona in Tucson, said he wondered whether the droplets inside the salt crystals could have been contaminated at some time after the crystal's formation. Squeezing a crystal can cause such droplets to change position inside the crystal, increasing chances of water entering from the outside and carrying bacteria in, for instance.

But if the bacteria are in fact 250 million years old, he said, it increases the chance that life can travel, inside rocks, between Earth and other planets, such as Mars. Rocks can be knocked off a planet when a meteorite slams into its surface.

In a recent study, Dr. Melosh said, he and his colleagues estimated that "it's overwhelmingly probable that rocks containing viable organisms have been transferred from Earth to Mars, and if there was ever any life on Mars, from Mars to Earth."

The longer an organism can survive, the better its chances of landing safely on another planet.

"We think a couple tons of Martian material per year falls on Earth," he said, and probably vice versa, too.

"Typically a rock will circulate for millions of years before it collides with another planet," Dr. Melosh said. "If organisms can be dormant for 200 million years, it's 200 times more probable that they will come from Earth to Mars."