Taxol producing fungus found in Montana woods

FOR CHEMIST Andrea Stierle, it was like searching for the proverbial needle in the haystack. She was scouring the ancient cedar forests in Montana, USA, for a fungus that produces a compound called taxol, which is used to treat ovarian cancer. And find it she did, though she herself had put the odds at 10 million to 1.

The fungus, Taxomyces andreanae, was scraped off the bark of a Pacific Yew tree whose location is kept a secret (Science, Vol 260, No 5105). Nor is anyone scurrying off to the forest to look for it, for Stierle and plant pathologist Gary Strobel of Montana State University recently announced that the fungus produces taxol even after it has been removed from its host.

So far the cultures at Montana State University have yielded only small amounts of taxol, but microbiologist Arnold Demain of the Massachusetts Institute of Technology believes the yield could be increased by supplying more oxygen to the fungus, or by genetically manipulating it to produce a better strain. It is also likely, suggests the Montana group, that some chemical in the host plant regulates taxol production by the fungus and this chemical can be used to ensure a better yield.

If extracting taxol from the fungus becomes commercially viable, it will bring down significantly the price of the drug, which is now produced in tiny quantities by the yew tree itself. Besides ovarian cancer, the drug is soon likely to be used to treat breast cancers too, which will increase the number of possible patients using taxol from 15,000 to 50,000 in USA alone.

A number of top US drug and biotech companies are bidding for the rights to manufacture taxol from the fungus. Regardless of who eventually gets the licence, cancer patients are sure to benefit.