National Geographic : 1993 Aug
IKE VENOM squirting from a fang, lethal cyanide poured daily from the Homestake Mine's gold-processing plant into South Dakota's White wood Creek. Mercury, arsenic, and sewage thickened the toxic flow. For a hundred years the stream ran gray and sterile through the Black Hills and beyond. "Even 30 years ago people thought it was wrong," recalls Jim Whitlock, a local resi dent. "But the Homestake Mine was the biggest gold producer in the Western Hemi sphere. It meant money, jobs, everything." Then time caught up with the Homestake. Citizens, state, and nation demanded action. By the late 1970s the company had largely cleaned up its ore treatment. But the question remained: How to safely rid effluent of the cyanide used for separating out the gold? "I thought bacteria could do it," said Mr. Whitlock, today a Homestake biochemist. "I collect ed samples of water exposed to the poison. They held cyanide-tolerant bacteria that actually feed on the poison's carbon and nitrogen. "We designed a bioreactor, a series of tanks in which the cyanide effluent moves slowly past feed ing bacteria. It worked. We still flush the final product into White wood Creek. Only now it's clean." Today fishermen regularly pull trout from the once poisoned creek. The triumph at Homestake already is leg end in environmental circles. It does not stand alone. In the United States at least 50 cleanup companies apply the technology known as bioremediation, siccing microbes on every thing from gasoline-soaked soil at the corner service station to EPA-designated Superfund sites strewn with the worst carcinogens. This is a heady time to be a microbe. ("Mi crobe" is merely a convenient name for any of hundreds of thousands of species of micro scopic organisms that flourish on earth; the most numerous are the ones we call bacteria.) Bacteria:Teaching Old Bugs New Tricks With clever coaching from microbiologists, bacteria and other "bugs" are being put to work in wondrous ways. "We've always been good at domesticating plants and animals," said Jerry Caulder of the Mycogen Corpora tion of San Diego. "Now we're learning to domesticate bacteria." Some microbes serve as factories-making pharmaceuticals, pesticides, solvents, and plastics. Some help make the snow at your ski resort. Some separate gold and copper from ores, OF GENES AND MEN "You can't be worried about making history you do itbecause it's exciting," says Ananda Chakrabarty, who in1972 genetically designed a bacterium that gobbles oil, thus inventing the first patented microbe inthe United States. Researchers have since isolated thousands of useful microbes. The world's most diverse "bug" bank, the American Type Culture Collection (facing page) keeps 55,000 micro scopic cell cultures in icy stock.