From a tenacious bug, a tonic for toxic waste
It sounds like the plot of a schlocky sci-fi flick: The year is 1956, and at a college laboratory in Corvallis, Ore., a food technologist wanders in one day to the refrigerated storage room only to discover that a dozen or so cans of ground beef sterilized by gamma radiation have started mysteriously to swell. Inside the cans, a microorganism with a reddish pigment has somehow survived the radiation and is growing. The reddish microbe--later dubbed Deinococcus radiodurans--goes on to earn a reputation as the toughest bacterium in the world, a Terminator-like bug that can quickly repair its own severed chromosome strands after being irradiated and can withstand at least 3,000 times the radiation that would kill a human.
Decades later, geneticist Michael Daly has shown that this tenacious bacterium could someday actually be put to good use: to clean up the mountain of nuclear waste generated by the Cold War. With some clever genetic engineering in his lab at the Uniformed Services University of the Health Sciences, the military medical school in Bethesda, Md., Daly and his colleagues have modified D. radiodurans so that it can partly break down toxic organic compounds such as toluene, a solvent present at many nuclear-waste sites. In the January issue of Nature Biotechnology, Daly and his fellow researchers report that they have added genes to the bug that enable it to transform ionic mercury, a dangerous heavy metal, to a less toxic state.
The nation's 113 federally managed nuclear-waste sites pose a gigantic problem, collectively covering an area the size of Delaware and Rhode Island combined. At 42 sites, 1.7 trillion gallons of ground water have already been contaminated--enough water to keep Niagara Falls flowing for 26 days. All told, some 49 million cubic meters of soil have been contaminated as well. Laid a meter deep, the contaminated soil would cover 10,000 football fields. "The American public," warns Secretary of Energy Bill Richardson, "has no idea how big, how vast, and how complex this problem is."
Money saver. In the past, the Department of Energy, which oversees the nuclear-waste sites, has sought to clean up its toxic slumgullions by either digging up the waste and placing it in landfills and above-ground vaults or burning it. But these methods, says Richardson, "are too expensive--it is going to take about 70 years to finish the job and cost about $150 billion. We can't wait that long." Bioremediation with D. radiodurans could be much cheaper and less time consuming. While the superbug does not reduce radiation, it can work in high-radiation areas where other microbes wither, and it has the potential to stabilize contaminated metals and organic compounds so that they don't seep further into the water supply and soil.
Daly's work with D. radiodurans is an outgrowth of his lifelong pleasure in dismantling things and putting them back together. When he was sent to England during one of his father's Foreign Service stints, Daly took to collecting and restoring antique scientific and musical devices while still in high school--old microscopes, an Edison phonograph--anything that moved and had a spring in it fascinated him. Daly, who earned his Ph.D. in 1988 at the age of 24, says that "genetic engineering is still a bit like playing with Legos for me. I feel great when I take something apart and put it back together again and it works."
D. radiodurans has not been tried in the field yet, and Daly guesses that it will take six years or more before the superbug, tailored to the wastes at each site, will be used in cleanup efforts. One plus is that the bacterium has not been known to cause death or disease in humans. Even so, genetically engineered microbes make many Americans nervous, and both Daly and Richardson anticipate a long review period before D. radiodurans is deemed safe for use. In the meantime, the seemingly scary stuff in the cans discovered more than 40 years ago looks less like the blob that ate Pittsburgh than an environmental boon for mankind.
This story appears in the January 3, 2000 print edition of U.S. News & World Report.