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Warrior Bug Tackles Waste

The Cold War may have ended several years ago, but it left behind some dangerous unfinished business: 3000 nuclear waste sites in the United States alone. Now researchers may have found a way to combat this waste buildup by using a genetically engineered microbe that resists radioactivity and breaks down chemicals at the sites. Experts say the bug, described in the October issue of Nature Biotechnology, could eventually help the U.S. government dig out of its 50-year-old toxic mess.

A team led by pathologist Michael Daly of the Uniformed Services University of Health Sciences in Bethesda, Maryland, and biochemist Larry Wackett at the University of Minnesota, St. Paul, enlisted a fairly common bacterium that thrives in arid environments. Able to withstand higher levels of radiation than any other known microbe, Deinococcus radiodurans is also easy to manipulate genetically. So the team fortified the bug with four foreign genes that enable it to break down organic substances.

The altered microbes bred easily, even in a radioactive chamber, by rapidly repairing DNA damaged by radiation. And they put their new genes to work, degrading toxic chemicals, such as chlorobenzene, that are commonly found at nuclear waste sites. "It's a new potential avenue opening up" for waste disposal, says Daly. He hopes that the organism can be further altered so that it uses the toxicants for energy rather than just breaking them down.

Deinococcus's ability to withstand radiation makes it "a mind-blowing bug," says Dan Drell, a biologist at the Department of Energy, which administers many of the nuclear waste sites. But he's not ready to sic the bug on any sites just yet. "I would want evidence that the genome, once modified, is reasonably stable," he says, to prove that it will maintain its new powers over time.