From leaves to oil

A cellulose-chomping, ethanol-producing microbe promises a way out of the fossil fuel crisis

Ten years ago, an assistant from a microbiology laboratory took a hike near the shore of the vast Quabbin Reservoir, which supplies water to Boston. At one point, he crouched alongside a brook in the shade of towering hemlock trees, dug up some moist dirt, put it in a jar and took it back to the lab.

Today, some investors are betting that the jar of dirt could help change the biofuels industry. Inside the jar, microbiology professor Susan B. Leschine found curious lollipop-shaped microbes with an uncommon ability to break down leaves and plant fibres into ethanol. For 30 years, Leschine has been researching this sort of thing and writing about it for publications such as the International Journal of Systematic and Evolutionary Microbiology.

Some venture capitalists in the area have convinced Leschine her tiny microbe could be big business. Now Leschine, who teaches at the University of Massachusetts at Amherst, is also chief scientist at SunEthanol, a start-up firm with about a dozen employees.

SunEthanol is just one of countless firms searching for ways to make cellulosic ethanol a commercially viable business. At the moment, unlike ethanol made from corn, not a drop of cellulosic ethanol is being commercially produced. Half a dozen pilot projects are being built8212;with the help of 385 million in Energy Department grants8212;but no one claims to have a sure thing.

A key part of the challenge is figuring out how to better break down cellulosic material8212;such as cornstalks or wood chips8212;into ethanol. Many firms are trying to do that in two steps, first breaking down cellulose into sugars and then fermenting sugars to produce ethanol for use in motor fuel.

Many companies are genetically engineering enzymes to do the first task. Those enzymes tend to be expensive. Last Monday, Genencor, a division of Danisco, announced that it had developed a new product, Accellerase 1000, that it said contains a combination of enzymes that reduces cellulosic biomass into fermentable sugars.

8220;Lots and lots and lots of groups and companies are looking for new cellulases,8221; or enzymes that process cellulose, said J. Craig Venter, who mapped the human genome. Venter8217;s company, Synthetic Genomics, is searching for naturally occurring chemicals that can turn sugar into diesel fuel. 8220;A key part of nature is breaking down plant debris,8221; he said. 8220;So we find all kinds of environments with unique cellulases in them.8221;

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Leschine says her microbe has the advantage of performing both the breakdown of plant fibres and the production of ethanol. 8220;Creating one microbe that does what enzymes and fermentation do is regarded as the Holy Grail because of the savings in costs,8221; she said.

For the microbe, the plant fibres are food while ethanol and carbon dioxide are waste products. 8220;These are tiny little cells we can8217;t even see. They don8217;t have mouths. How do they do it?8221; she said with a sense of wonder.

For years, Leschine scoured soil samples from around the world in search of the perfect microbe, one that would excel at breaking down what nature casts on the ground. She found not far from her lab. She has dubbed her microbe the Q microbe for the Quabbin Reservoir.

Most microbes have about 20 machine-like proteins for absorbing sugars; the Q microbe has more than 100 for various nutrients, half of them for sugars, she says. The Q microbe also works in moderate temperatures, making it useful for manufacturing.
-Steven Mufson The Washington Post