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Scientists Work on a One-Step Biofuel

10:09AM Jun 26, 2014

University of Georgia-Athens researchers develop a process that allows direct conversion of switchgrass into ethanol without using expensive enzyme pre-treatment to break down the cellulose fibers.

Using a genetically engineered bacterium, University of Georgia-Athens researchers say they can convert switchgrass into ethanol directly, without any expensive pre-treatment with enzymes to break down the cellulose fibers into something suitable for fermentation. The new microbe, called Caldicellulosiruptor bescii, can not only convert biomass cellulose to sugars, but also turn the sugars to ethanol for fuel.

The conversion process is similar to how traditional microbes turn barley into beer or grapes into wine, according to the researchers.

"Given a choice between teaching an organism how to deconstruct biomass or teaching it how to make ethanol, the more difficult part is deconstructing biomass," said Janet Westpheling, a member of the research team. "Now, without any pre-treatment, we can simply take switchgrass, grind it up, add a low-cost, minimal-salts medium, and get ethanol out the other end. This is the first step towards an industrial process that is economically feasible."

Experiments to date have shown the bacterium can convert switchgrass to fermentation products that are 70% ethanol. Researchers also applaud its versatility. The Georgia team reports they will be able to produce other fuels, such as butanol and isobutanol.

"This is really the beginning of a platform for manipulating organisms to make many products that are truly sustainable," Westpheling said.

The findings were published in the proceedings of the National Academy of Sciences.