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  National Geographic 14 Mar 06
Termite Power: Can Pests' Guts Create New Fuel?
John Roach for National Geographic News

Tiny microbes that live inside termites may one day help cure the world's energy woes, according to scientists. The researchers are trying to understand how bacteria that help termites digest wood and other plants release the hydrogen that's trapped in the material.

"We don't understand the full details of how the process occurs," said Jared Leadbetter, an environmental microbiologist at the California Institute of Technology in Pasadena. "But once we learn more about it, many things become possible."

For example, he says, biotech engineers could mass-produce the tiny microbes for hydrogen production on an industrial scale. The hydrogen could then power hydrogen fuel cells, a type of battery that emits only water.

But reaching large-scale production, Leadbetter cautioned, "is a pretty tall order." It would depend on how well the research is funded and how it progresses over the coming years, he said.

Daniel Kammen, director of the Renewable and Appropriate Energy Laboratory at the University of California at Berkeley, agreed there are hurdles to overcome, but he said the potential applications are "very positive."

"Neat stuff can happen in this area," he said. Kammen imagines a day when "little digesters"--a termite germ-derived technology--sit in people's garages and process piles of woody waste to produce enough hydrogen to power cars and homes. The concept would mean no more trips to the gas station or having to pay the electric company for power. "I think that's the natural way to go long term," Kammen said.

Termites and Microbes

For now Leadbetter is content to learn more about the insects and the inhabitants of their guts. "This is a fascinating group of insects that do a fascinating activity and play important roles in the global ecosystem," he said.

According to Leadbetter, an estimated 2,600 termite species comprising more than a quadrillion--that's 1 followed by 15 zeros--individuals are crawling the Earth. "In terms of current activity, they do turn over a lot of plant material," he said.

Hydrogen and other gases are produced inside termites' hindguts--an area roughly equivalent to the colon in humans--where "several hundred" unique microbe species reside, Leadbetter said. The species of microbes vary among termite species. The microbes and termites have what scientists call a symbiotic relationship: Neither could exist without the other.

The termites use their jaws to turn the woody plant material and soil they bore through into tiny particles that the microbes can process. The metabolism of the microbes in turn converts the woody food to acetate, which is essentially a kind of vinegar that the termites absorb as their major nutrition source.

Termite Power

Such symbiotic relationships are fairly common in nature. Cows and other animals rely on microbes to process the foods they chew into energy. Even human guts are filled with microbes.

But cows eat grass, not wood, and they emit lots more methane per pound of plant material processed than termites do, Leadbetter said. Methane is a so-called greenhouse gases that traps heat in Earth's atmosphere.

According to the U.S. Environmental Protection Agency, cows and other ruminant livestock are responsible for 28 percent of global methane emissions from human-related activities. By contrast, termites are responsible for about 4 percent of global methane emissions. And the microbes in human guts can't process woody plant material like those in termites and cows.

So Leadbetter and colleagues at Diversa Inc. in San Diego, California; the U.S. Department of Energy's Joint Genome Institute in Walnut Creek, California; and Costa Rica's National Biodiversity Institute are focused on termites and their gut microbes.

If they can figure out which enzymes--or proteins inside the microbes--break apart the wood into materials like hydrogen, the researchers in principle could scale up the process for industrial applications. And given all the wood chips and leftover waste from harvesting trees and other crops, that would be a "novel way of converting low-value starting material into a higher value product," Leadbetter said.
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