How Heat-Loving Fungi Could Cook Up Better Biofuels

One of the unexpected wonders of composting is how much heat a compost pile can generate. A 10-gallon pile in your backyard can reach upwards of 120 degrees Fahrenheit in a few days, while an industrial-sized pile might hit 160 degrees. This is good news for decomposers like bacteria and fungi, which thrive in such conditions and can break down tough plant materials into a wafting pile of brown loam.

As a result, a team of scientists that includes researchers at a Department of Energy lab is looking to the type of heat-loving fungi found in compost piles for a better mechanism to break down plant mass. What they've found could make biofuel production faster and more cost-effective, they say.

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Most of the existing biofuel plants in America break down starchy corn kernels into sugars that are processed into ethanol. But plant materials like corn stalks also contains loads of energy-rich cellulose that could be transformed into fuel if there was a cost-effective way to get at those resources.

The earth already plays host to a horde of organisms that are great at breaking down plant materials, so researchers are gathering them up and poking into their inner workings in order to find the tools they use. They’ve looked in termite guts for the enzymes that decompose wood, and in the digestive systems of animals like pandas, zebras, and cows for enzymes that break down bamboo or grass.

Many of the cellulose-chomping enzymes that scientists have isolated, though, work at room temperature or body temperature. There are major advantages to breaking down cellulose at higher temperatures, though. It happens faster, and there’s less time for contaminants to sneak into the system. The enzymes that the Department of Energy scientists and their colleagues found work at temperatures ranging from 104 to about 170 degrees Fahrenheit, making compost piles a natural fit. The team has parsed out and published the complete genome of the heat-loving fungi, and the code that creates the enzymes can be patched into fast-growing bacteria.

There are still questions about whether biofuels, even cellulose-based ones, make long-term environmental or economic sense. There’s also a moral question: if biofuels drive up food and water prices, depriving low-income people of basic resources, should we still create them? America’s still as invested in biofuels as it is in any clean-energy technology, though, and making the production process more efficient can only help.

Photo courtesy of Adrian Tsang, Concordia University, Canada