VOA标准英语2010年-Chemists Take First Steps in Making Ca（在线收听）

The drug Taxol is a powerful weapon in the fight against cancer, but it's very expensive and complicated to manufacture.

Now, scientists at Tufts University and the Massachusetts Institute of Technology (MIT) say they've taken the first steps to make the drug using a common bacterium.

Taxol was first found in the bark of the Pacific Yew tree decades ago. Like many complex chemicals, it is the result of a series of steps that in this case all happen in the tree.

MIT chemical engineering professor Gregory Stephanopoulos and colleagues have begun the process of making Taxol in the lab, starting with a genetically engineered form of E. coli, a safe variety of the bacterium that's usually in the news in stories about food poisoning.

"It is the bacterium of choice for a lot of molecular biology," he explained, "so there are many, many tools available for working with E. coli, and these tools allow researchers to 'knock out' genes and introduce new genes into E. coli."

By genetically manipulating the microbe, the scientists were able to take the first chemical steps in the process that, in nature, eventually leads to Taxol.

"So E. coli, that little bacterium, acts as a little chemical factory. In this way it replaces an equivalent chemical process which may require high temperatures and pressures and expensive solvents and all of these things — all of that is replaced by a single bacterium that's been property engineered to do that," said Stephanopoulos.

Another advantage is that the intermediate chemical molecules can themselves be studied and tested for any possible therapeutic effects they might have.

Although the process, if perfected, may synthesize a drug found in tree bark, Stephanopoulos says it's important to remember that Taxol — and possibly other, undiscovered medicines — originate in nature.

"It relies on samples from plants from the rainforests, from different sources, because the diversity that exists in these habitats gives the opportunity for the production of many, many, many different types of molecules, some of which may have very potent therapeutic properties."

So he says it is important to continue prospecting in the natural world in the hopes of discovering pharmaceutical molecules, even if they are eventually manufactured in ways different than how they are grown in nature.

MIT chemical engineering professor Gregory Stephanopoulos and his colleagues published their research in the journal Science.