Digging for Cures

By Jocelyn Selim|Friday, December 01, 2000

When biologists Jo Handelsman and Robert Goodman set off in search of the next miracle antibiotic, they didn't look any farther than the dirt in their backyard at the University of Wisconsin at Madison. "Soil is by far the richest source of biologically active molecules on Earth," says Handelsman. Each cubic inch contains millions of bacteria, many of which release chemicals to help them compete in the overpopulated environment. But more than 99 percent of those microbes have not been tested for useful compounds because it is so difficult to check them one by one.

Handelsman and Goodman speed things along by taking a quick genetic snapshot of all the bacteria in the dirt. After collecting a soil sample, they freeze and thaw it rapidly, thereby cracking open the microbes and releasing their genetic material. The genes are sorted and inserted into a standard laboratory host bacterium, which is screened to see if its new gene sequences manufacture any potentially useful drugs. "We've already found what looks like a structurally new antibiotic," says Handelsman. And she notes the genetic snapshot technique is not restricted to dirt: "We can do this for any microbe whose environment prevents it from being cultured in the lab." The team next plans to look at bacteria in the guts of caterpillars.

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