A Better Biofuel Bug

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A genetically modified bacteria that efficiently convert biomass into sugar.

bug

FUENTE – TechnologyReview.com – 18/03/09

Cellulose-eating microbe: Steve Hutcheson, president and CTO of the company, shows a culture of the bacterium S. degradans, found in the Chesapeake Bay more than 20 years ago. 

A tiny microbe found in the Chesapeake Bay is the focus of intense study for a biotech startup in College Park, MD. A  rare, cellulose-eating bacterium has been gentically modified to break down and convert cellulose into sugars necessary to make ethanol, and it recently completed its first commercial-scale trial. Earlier this year, the company ran the modified microbe through a series of tests in large fermenters and found that it was able to convert one ton of cellulosic plant fiber into sugar in 72 hours. The trial, researchers say, illustrates the organism’s potential in helping to produce ethanol cheaply and efficiently at industrial scales. Zymetis is now raising the first round of venture capital to bring the technology to commercial applications.

Scott Laughlin, says that for the past two years the company’s scientists have worked to retool and pump up the tiny organism. The microbe’s main advantage is its ability to naturally combine two major steps in the ethanol process, which the company says could considerably slash the high costs of producing ethanol from cellulosic biomass like switchgrass, wood chips, and paper pulp. The company is running the organism through a series of trials to study how the system could be applied at an industrial scale.

Ethanol production from cellulosic sources is an expensive multistage process. The cellulosic feedstock is first pretreated with heat and chemicals to break down the material’s tough cell walls. Expensive manufactured enzymes are then added to the mix to convert purified cellulose into glucose, which is then treated with yeast that turns the sugars into ethanol. As a result, scientists and several startup companies are developing improved microbes that could accomplish several of these steps, thus making the resulting biofuels more competitive with fossil fuels.

Toward that goal, Laughlin says that the company has developed an ethanol-producing system that revolves around a microbe that quickly and efficiently combines the first two steps of the conventional ethanol process. “It has the ability to break down whole plant material, and it excretes enzymes that break down cellulose, [which works] very well in solution,” says Laughlin.

The microbe that the company is banking on is Saccharophagus degradans, a bacterium found in the marshes of the Chesapeake Bay that eats away at dead plant material and solid waste, breaking them down into glucose. In 2003, Steve Hutcheson, a professor of cell biology and molecular genetics at the University of Maryland, combed through the organism’s genome and discovered that it possessed a combination of enzymes that broke down the tough cell walls in dead plants and converted remaining cellulose into sugars–two valuable properties in producing cellulosic ethanol. 

 

 

Author: J. Chu

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