11/19/2004

Position Available:Indestructible BugsTo Eat Nuclear Waste

Scientists Envision New RoleFor Sturdy Bacteria Breed;Creating 'Super Conan'

By JOHN J. FIALKA Staff Reporter of THE WALL STREET JOURNALNovember 16, 2004; Page A1

SAVANNAH RIVER SITE, S.C. -- Eight years ago, scientists using a metal rod here to probe the radioactive depths of a nuclear-waste tank saw something that shocked them: a slimy, transparent substance growing on the end of the rod.
They took the specimen into a concrete-lined vault where technicians peered through a 3-foot-thick window and, using robot arms, smeared a bit of the specimen into a petri dish. Inside the dish they later found a colony of strange orange bacteria swimming around. The bacteria had adapted to 15 times the dose of radiation that it takes to kill a human being. They lived in what one scientific paper calls a "witches' brew" of toxic chemicals.
It was a step forward for the U.S. Department of Energy, which has been looking for a few good bugs -- in particular, members of an emerging family of microbes that scientists call "extremophiles." These microbes can survive in some of Earth's most inhospitable environments, withstanding enormous doses of radiation, thriving at temperatures above boiling, and mingling with toxic chemicals that would kill almost anything else.
That makes them a potentially valuable tool in the Energy Department's effort to clean up vast amounts of nuclear waste, including the Savannah River Site near Augusta, Ga., and the Hanford Site near Richland, Wash. The department says it could cost as much as $260 billion to clean up its messes with conventional methods, which rely heavily on chemical treatment and robots. Using extremophiles could slash that bill.
Extremophiles eliminate toxins by ingesting them and breaking them down into relatively harmless components. The microbes also can reduce the hazard of radioactive wastes by changing them into insoluble forms that are much less likely to leak into aquifers and streams.
K. radiotolerans, seen through an electron microscope. At left, a colony of the bugs; at right, a single bacterium.
Outgoing Energy Secretary Spencer Abraham predicted this year that "in the not-too-distant future," extremophiles will be cleaning up nuclear waste and munching the pollutants of coal-fired power plants, including carbon dioxide, one of the causes of global warming. The National Aeronautics and Space Administration thinks if it can understand the mechanism that the bugs use to survive radiation, it might be able to use it to protect space crews against radiation on long voyages. The National Institutes of Health hopes the microbes' peculiar powers might help cancer patients survive more-intensive radiation therapy.
So far, scientists say that the extremophiles they have found in nature aren't harmful to humans. Laboratory-engineered modifications of these bugs, however, are likely to cause some controversy because no one knows what their long-term effects might be.
The berry-shaped bug discovered at the Savannah River Site was christened Kineococcus radiotolerans. Scientists have probed 95% of its genetic structure. They know what it does and what it eats -- it loves malt sugar -- but after 50 years of studying these sorts of bugs, they have no idea how they survive. Radiation shatters the genetic structures of living things, but extremophiles snap themselves back together in a matter of hours.
Christopher Bagwell, a microbiologist here, says Kineococcus has shown the ability to break down herbicides, industrial solvents, chlorinated compounds and other toxics, all while growing in a radioactive environment that shrivels other living things and turns glass brown.
Scientists know of at least a dozen extremophiles. The first was discovered in 1956 in Corvallis, Ore. Scientists were zapping cans of horse meat with high radiation, trying to establish the preservative value of food irradiation. One can developed an ominous bulge. Inside, the scientists isolated pink bacteria they had never seen before.
They gave it the scientific name Deinococcus radiodurans. But researchers were so amazed by the bug's resilience that some years later, they nicknamed it "Conan the Bacterium," spawning a folklore and debate among scientists that continues today. Because the microbes endure radiation at levels higher than any natural source, some scientists have argued that they must have ridden in on comets. Others speculate that they were the Earth's first residents after the planet was born in a radioactive explosion.
"Because of the amazing abilities of these organisms, they sort of bring out the poet in people," says John R. Battista, a microbiologist at Louisiana State University. He says speculation about outer space origins is like engaging in "mythology."
Extremophiles have recently been found on barren mountain tops and in the frozen plains of Antarctica, Dr. Battista says. He believes they are simply harmless, opportunistic creatures that have found a way to survive in conditions of severe drought, which, he says, damages cells in much the way radiation does. "It just waits until it gets dried out and then it gets blown somewhere else."
The original Conan proved to be a wimp among extremophiles. It could handle radiation, but not the solvent toluene and other chemicals normally found in bomb makers' wastes. So, in 1997, the Energy Department started work on a genetically manipulated bug that researchers called Super Conan.
Super Conan now lives in a petri dish at the Uniformed Services University of the Health Sciences, a U.S. military research facility in Bethesda, Md. It can handle nasty chemicals as well as radiation, but the researcher who developed it, Michael J. Daly, says the government is afraid to let it out.
"We're at a point where we could do some field trials," he says, adding that his sponsors at the Energy Department doubt the public is ready for the release of this laboratory-engineered bug into the environment. It might eat nuclear wastes, but they worry about what else might it do, he says.
Rather than confront such touchy matters, the department is confident it can find Super Conan's equivalent in nature, says Ari Patrinos, the department's director of biological and environmental research. He estimates that fewer than 1% of the Earth's bacteria forms have been identified: "There are plenty out there for our needs. We just have to pick and choose."
That's where Kineococcus comes in. The Savannah River Site, slapped together in the early 1950s to keep the U.S. ahead of the Soviet Union in the race to produce hydrogen bombs, has 49 underground storage tanks containing 35 million gallons of radioactive waste. The Energy Department has a much bigger mess at the Hanford site, a World War II weapons plant where leaking tanks have contaminated 80 square miles of groundwater with radiation and toxic chemicals.
Because the new orange bug made its home in nuclear wastes, no one can argue that putting it back there would be unnatural, say the scientists here. They believe they can grow kineococcus in petri dishes and then inject it into tanks and underground plumes of leaking wastes.
But Dr. Bagwell thinks it will take five more years of peering into the bug's genes before attempting such experiments. Twenty percent of the microbe's genetic structure, he says, involves "unknown functions."

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