February 16, 2007 2:51 PM PST
A new ally in the energy crisis: Termites
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Researchers at universities and private companies are scanning the DNA of the microbes that live inside the guts of termites and wood-eating beetles in an effort to decipher the processes these creatures employ for turning wood into food. The same processes and enzymes could be used, researchers believe, into transforming wood scraps into transportation fuel at human factories.
Termites "are like miniature factories," said Mel Simon during a presentation at the American Association for the Advancement of Science meeting taking place in San Francisco. Simon is a professor at the California Institute of Technology and founder of Diversa, which specializes in exploiting naturally occurring enzymes for industrial use.
The wood-to-food process in termites starts with grinders in the front end, he said. Ground up pulp then proceeds to a pre-gut that chemically starts to break it down. Some types of termites have 400 to 500 species and subspecies of microorganisms in their guts, which break down plant material further by excreting enzymes. The hundreds of different species, he added, are all arranged methodically in the gut of the animals.
"They use a variety of intermediaries, not just bacteria. There are fungi, protozoa," he said. "We know very little about the guts inside of termites."
Scientists at the Joint Genome Institute are extracting the contents of the guts in certain termite species and scanning the DNA of several of the microbes at once, Simon said.
So where do you find the best microbes? The Tropics, where plant matter rots quickly, are good place to start. Diversa has a deal with Costa Rica that gives the company some exclusive rights over that country's termites for this kind of research.
"We haven't even begun to methodically examine all of the insects in the Brazilian rainforest," said Steve Chu, director of Lawrence Berkeley Lab, who also participated in the presentation.
If the research pans out, ethanol providers won't have rooms full of termites gnawing on two-by-fours. Instead, researchers hope to replicate the chemical processes that take place in termite guts synthetically. Alternatively, the microbes can be reproduced and bred for greater efficiency. Microbes in controlled environments could then produce ethanol.
Simon, though, added that genetic enhancement won't likely lead to an ecological disaster.
"No one can even imagine of a superbug that will eat your table," he said.
Simon, Chu and Christopher Somerville from Stanford University, who also participated in the presentation, agreed that biofuels like ethanol could play a significant role in reducing fossil fuel consumption in the U.S. over the next 15 years and beyond. A Department of Agriculture study in 2005 noted that the U.S. produces about 1.3 billion dry tons of excess biomass a year, and about 60 percent of that, or 780 million dry tons, is agricultural waste.
"That could produce about 130 billion gallons of ethanol," said Somerville. The U.S. uses about 140 billion gallons of transportation fuel a year, he added. Ethanol has only about two-thirds of the energy content of gas, so waste product ethanol couldn't fully displace gas. Still, the figures indicate that waste product ethanol could, potentially, replace nearly 60 percent of the gas consumed today.
Mass producing ethanol from biomass and agricultural waste (so-called cellulosic ethanol) will, however, take an extensive amount of work. Plants will have to be bred so that they generate a larger amount of energy and require almost no fertilizer or irrigation. (Scientists would also have to make sure that removing plant scraps from fields won't hurt the quality of soil.)
Microbes also have to be bred so that they can more efficiently turn plants into cellulose, then turn cellulose into sugar, and then sugar into alcohol that can be run in cars. Cellulosic ethanol can be produced now, but it's expensive and time-consuming.
People have to buy new cars too, said Somerville. Only about 4 percent of the cars in the U.S. can run on fuel that consists of more than 10 percent ethanol.
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