Few people enjoy getting their hands dirty more than Chaitan Khosla. Among the leaves and sticks and stones, the Stanford University chemical engineer is pioneering a radical method for pro-ducing new medicines to treat infections, cancer and other scourges―with the help of tiny, genetically modified soil bacteria. Some lab. Yet in the past half-century microbe and plant samples from exotic locales around the world have been one of the richest sources of new drugs. Soil bacteria and fungi are particularly proficient at producing natural chemical weapons, apparently as part of a subterranean arms race to spew out toxic chemicals to kill rival species. They already have contributed to the development of the antibiotics erythromycin and tetracycline, the cancer chemotherapy drug doxorubicin, Wyeth's transplant drug Rapamune, and Merck's cholesterol-lowering medicine, Mevacor. Khosla is pushing nature's ingenuity one step further. By selectively altering key enzymes in bacteria's chemical weapons factories, he hopes to redesign microbes so they are more likely to produce compounds that can fight human disease. "The goal is to speed up evolution to make drugs cheaper, better and faster," says Khosla.
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