Researchers isolate fuel compounds from fungi

Posted Dec. 29, 2010

Researchers at Montana State University have discovered a natural fungus that's capable of producing eucalyptol, also called cineole, a rare compound previously only known to be found in eucalyptus bark. The discovery, according to Gary Strobel, professor of plant sciences and plant pathology and lead on the project, was first made by his research assistant Angie Tomsheck after studying plant samples Strobel gathered in the Canary Islands off the northwest coast of Africa.

"[Cineole] smells like a eucalyptus forest," Strobel said.

Shockingly, Strobel collected the sample from a laurel tree. The eucalyptol had been produced by a fungus, called hypoxelon, which Strobel had also collected in his search for endophytes. Strobel said eucalyptol is monoterpene and is considered a type of myco-diesel, an umbrella term Strobel uses to describe the range of compounds the fungi are able to produce. Although eucalyptol has the potential to be a diesel additive, it's likely a stronger candidate to become a gasoline alternative due to its high octane rating of 95, Strobel said.

"We found a patent that had been granted many years ago to a Japanese scholar that indicated cineole could be added eight-to-one to gasoline with an octane rating of 95," Strobel said. "In other words, someone using the compound could use eight times less gasoline to run their vehicle."

In addition to producing eucalyptol, Strobel and his team found that the fungi is also capable of producing derivatives of benzene, naphthalene and cyclohexane, all of which are valuable constituents of diesel fuel.

"When I look at the chemistry of these molecules, this stuff will run a small diesel engine, there's no doubt about it," Strobel added.

To collect the various bioderived compounds released by the fungi, Strobel said the team uses cylindrical metal objects he calls "carbon traps" that can capture various odors emitted by the fungi. The odor can then be analyzed using a gas chromatography mass spectroscopy to determine the compound.

"We can do about a five-liter fermentation and can get tenths of a milliliter of product," Strobel said, adding that scale-up and economic feasibility issues are inherent in the undertaking. "That's only with an inefficient gas trap. We can get enough stuff to analyze, burn and look at, and that's something we hadn't been able to do until now."

Despite the long-term hurdles associated with scale-up, Strobel's work hasn't gone unnoticed however. The U.S. DOE awarded more than $300,000 to Strobel and his team to continue their work. He said the partnership with the DOE could accelerate the development of modifying the fungi utilizing the DOE's robust gene-sequencing technology.

"I have a strong feeling that there are organisms out there as we speak doing these interesting little tricks," he said. "Whether we can commercialize it, I don't know. What we do know is that the product is usable and they're desirable products."