Star of a mushrooming field

September 28, 2001

Steve Farrar meets a man who travels the world seeking new fungi whose biochemical trickery could one day save human lives.

In 1987, Gary Strobel had a life-changing clash with the establishment. At the time it seemed like a catastrophe. But the events of that year would ultimately lead him to ditch the study of plants, which stretched back to his childhood in Ohio, for a daredevil lifestyle hunting fungi in some of the world's most exotic locations.

The trauma began when six enforcement officers from the Environmental Protection Agency arrived at Strobel's door. News of his work had spread, and the plant pathologist was in trouble. Strobel had injected 14 elm trees with a mutated form of a bacterium he had found on wheat. He believed the anti-fungal agent that the microbes produced could protect trees from the fungus behind Dutch elm disease like a bacterial "vaccine".

EPA regulations on the release of genetically engineered organisms demanded that he clear bureaucratic hurdles to get official approval. Feeling that the rules were inappropriate and would delay his work for a year, Strobel flouted them. The authorities threatened him with fines, imprisonment and even with ending all federal funding to Montana State University, where he held an endowed chair. Few of his colleagues stood by him. The pressure was intense. He resolved the issue by taking a chainsaw to the trees.

Disillusioned, Strobel threw himself into his research. His hunt for ways to exploit his bacterium has led to therapies for human fungal diseases. Then a fellow scientist suggested he might search for a new, natural source of the successful anti-cancer drug taxol, an expensive compound isolated from the yew tree.

Strobel abandoned his plant research. "I said 'I'm going out to find fungi that make taxol'," he recalls. It took just a few years for him to identify Taxomyces andreanae growing in Montana's Glacier National Park nearby. His paper on it in the journal Science in 1993 brought inquiries from 20 to 30 drugs firms. One Japanese business had a representative heading for Montana on the first available flight. The prospect of a new way to churn out taxol was too good to ignore. That fungi are easy to modify genetically also raised the possibility of artificially pepping up the natural compound-producing process.

Strobel's worries about where he fitted into the scientific community after the Dutch elm furore faded before such commercial interest. Mycology, the study of fungi, has long been starved of funds, and few get the chance to pursue it. But Strobel saw there was now an opportunity to specialise in the field and he grasped it. It was a decision he has never regretted.

He calls it fishing. Fungi live in every habitat imaginable. Strobel manages a couple of trips a year to search for plants in particularly interesting environments that might be home to fungi unknown to science. He flew by helicopter to the isolated peaks of Venezuela's tabletop mountains. Botanists guided him to a secret location in an Australian gorge to check for fungi amid living fossil pine trees. He has searched in South American river banks, Papua New Guinean hill villages and Himalayan forests.

He returns to Montana with samples, and his team extracts the fungi living hidden within them and isolates interesting bioactive compounds. The material is often sent out to a network of scientists across the US who help analyse the compounds these organisms synthesise and find the genes responsible.

Fungi employ a huge range of unique biological tricks in their ceaseless chemical war with each other. Inside their cells, they undertake combinatorial chemistry on a scale that drug companies could only dream of. Among this myriad of organic compounds are some that will prove very useful to humankind. Strobel knows that scientists have barely scratched the surface of fungal biology, but he is doing his best to change that.

Industry lends a helping hand. Strobel has about 50 patents on the substances he has found, and his licensing deals with drugs giants such as Bristol-Myers Squibb and Eli Lilly generate a small revenue.

Strobel tries to help those indigenous people he encounters in his work, providing them with the equipment and funding the advanced studies they need to continue the search for new fungi for themselves.

So far, the development of his discoveries has been slow. There has not been a blockbuster drug from one of his fungi - not even the taxol producer. But Strobel is hopeful that among the compounds identified will be some that make a real difference. In the meantime, he will keep scouring the world for more.


Biochemical wonders of the fungal world

Muscodor albus and Muscodor roseus (Honduras and Australia)

This Honduran fungus killed all the others sharing its collection box on its trip to Montana.

It seems that, with a good supply of nutrients, it can produce a potent mixture of volatile antibiotics that allow it to wipe out potential rivals. Strobel has since discovered two related species in the Australian outback.

Muscodor , to be detailed in the journal Microbiology , could be used to treat food, decontaminate surfaces and perhaps even treat human infections.

Pestalotiopsis microspora (Nepal)

On a yew tree in the Himalayan foothills, Strobel found the genetic scavenger of the fungus world.

It is the most genetically transformable fungus known: it absorbs genetic material from other organisms then allows the stolen genes to replicate and function in their new host.

Cryptosporiopsis quercina (China)

This fungus produces a chemical called cryptocandin that effectively tackles skin and nail infections on human volunteers.

The compound, isolated from a fungus found in the bark of a Chinese medicinal plant, is one of the most potent anti-fungal agents yet found. It makes another compound, cryptocin, that is particularly effective against the organism responsible for rice blast, one of the most devastating plant diseases.

Pestalotiopsis jesteri (Southern Highlands, Papua New Guinea)

A Huli tribesman scaled an oak tree to retrieve wood samples for Strobel. Among the 18 fungi he found was Pestalotiopsis jesteri , which synthesises a previously unknown compound with anti-fungal and anti-cancer properties that could tackle some of the deadliest plant diseases.

Seimatoantlerium tepuiense (Venezuela)

Dropped by helicopter on one of the spectacular tepuis - tabletop mountains that rise up to 3,000m above Venezuela's forests - Strobel found four new genera of fungi in 20 minutes.

In a beautiful flower growing amid the twisted rocks, he isolated the taxol-producing Seimatoantlerium tepuiense .

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