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Fungus breathes life into biofuels

A reddish microbe found on the inside of a tree at a secret location in the rainforests of northern Patagonia could unlock the biofuel of the future, say scientists.

Appearing in the journal Microbiology, the discoverers have coined the term 'myco-diesel' - a derivation of the word for fungus - to describe the bouquet of hydrocarbons that it breathes.

"This is the only organism that has ever been shown to produce such an important combination of fuel substances," says Gary Strobel, a professor of biology at Montana State University.

"The fungus can even make these diesel compounds from cellulose, which would make it a better source of biofuel than anything we use at the moment."

Serendipity

Strobel says that he came across Gliocladium roseum thanks to "two cases of serendipity."

The first was in the late 1990s, when his team, working in Honduras, came across a previously unidentified fungus called Muscodor albus.

By sheer accident, they found that M. albus releases a powerful volatile antibiotic.

Intrigued by this, the team tested M. albus on the ulmo tree, whose fibres are a known habitat for fungi, in the hope that this would show up a new fungus.

"Quite unexpectedly, G. roseum grew in the presence of these gases when almost all other fungi were killed. It was also making volatile antibiotics," says Strobel.

"Then, when we examined the gas composition of G. roseum, we were totally surprised to learn that it was making a plethora of hydrocarbons and hydrocarbon derivatives. The results were totally unexpected and very exciting, and almost every hair on my arms stood on end."

Strobel's team put the G. roseum through its paces in the lab, growing it on an oatmeal-based jelly and on cellulose.

Extractor fans drew off the gases exuded by the fungus, and analysis showed that many of them were hydrocarbons, including at least eight compounds that are the most abundant ingredients in diesel.

Direct process

Biofuels have been promoted as good alternatives to oil, which is sourced from politically volatile regions and is a major contributor to the greenhouse effect.

One of the downsides of biofuels has been their impact on the world food market, because the present generation of fuels is derived from food crops that are grown on farmland.

Another avenue of exploration is in cheap, plentiful non-food fibrous plants and cellulose materials, such as switchgrass, wood chips and straw.

But these sources, hampered by costs and technical complications, are yet to reach commercial scale.

"G. roseum can make myco-diesel directly from cellulose, the main compound found in plants and paper," says Strobel. "This means that if the fungus was used to make fuel, a step in the production process could be skipped."

Instead of using farmland to grow biofuels, G. roseum could be grown in factories, like baker's yeast, and its gases siphoned off to be liquefied into fuel, he suggests.

Another alternative, he says, would be to strip out the enzyme-making genes from the fungus and use this to break down the cellulose to make the biodiesel.

Strobel says Montana State University had filed patents for the fungus, proceeds of which would be shared with local people.

G. roseum is a variant of a known fungus species called Gliocladium. "It might be" common in some forests, says Strobel.

Asked where the fungus had been found, he pointed to the experiences of the 1848 gold rush and says the location had to be protected: "The answer to that is, what if we pushed ourselves back about a hundred and fifty years and you heard a story about a guy finding gold out in California?"