Cooperative Institute for Research in Environmental Sciences

chlorinated and man-made, it is difficult for nature to clean up.

One natural exception is the bacterium Sphingomonas chlorophenolicum, which likely developed its pathway for breaking down PCP in the few decades since the chemical's introduction. The process is cumbersome, requiring several enzymes that run into problems along the way. One intermediate product is even more toxic than the original pollutant and can be harmful to the bacterium. "The enzymes don't do a good job, probably because they just haven't had enough time to evolve," said Copley. "They don't have good control over the chemistry." Some genetic engineering could smooth out the process. Students and post-docs from Copley's group are cloning the genes that encode the chomping enzymes and putting them into the bacterium E. coli. They are using in vitro evolution techniques to generate tens of thousands of variations of the enzymes to identify which ones do the best job. Through this process, Copley hopes to select for better enzymes that can then be put back into the original bacterium. If Copley and her team succeed, S. chlorophenolicum may become the PCP-eating champion of the world.

"This is a novel pathway that has evolved very recently, offering a rare glimpse into evolution in action," said Copley. "It represents an exciting opportunity to both study evolution and help solve a human health and environmental problem."

"How do you evolve new enzymes and new metabolic pathways? We want to understand the process on a molecular level."

If Copley can do that, PCP, long considered difficult to destroy, may have reason to start shaking in its chlorine bonds. Introduced in 1936, PCP worked as an herbicide, algicide, fungicide, and insecticide, and was a widely used wood preservative and disinfectant until it was largely banned in the United States in 1987. Today it's used for mainly industrial tasks: to make utility poles, railroad ties, and wharf pilings last. Exposure to high levels of PCP can induce fever, damage the liver and immune system, and possibly cause cancer. Because PCP is both highly

Few bacteria would choose the hazardous man-made chemical pentachlorophenol (PCP) from the menu of microbial delights. But one "bug" is giving it a shot. It's the best-described of only a handful of bacteria known to break down the pollutant. One problem though: it's not particularly good at its job, yet.

There's a chance that modern science could help this microbe sort out its digestive problems. That's why CIRES Fellow and Professor of molecular, cellular, and developmental biology Shelley Copley is leading a research team aimed at engineering a more efficient form of the bacterium. "The goal is not just to make a better bug, but to understand what it took to make it happen," said Copley.