New lignin 'lite' switchgrass boosts biofuel yield by more than one-third

Feb 14, 2011
Fermentation research by Oak Ridge National Laboratory's Jonathan Mielenz confirmed that The Samuel Roberts Noble Foundation had developed a strain of switchgrass that produces about 33 percent more ethanol than conventional switchgrass. (ORNL photo/Jason Richards)

Bioethanol from new lines of native perennial prairie grass could become less costly because of plant engineering by The Samuel Roberts Noble Foundation and fermentation research at Oak Ridge National Laboratory.

In a paper published in the , researchers describe their transgenic version of switchgrass as one that produces about one-third more ethanol by fermentation than conventional switchgrass. This improved plant feedstock will be able to generate more biofuel per acre, benefiting not only the transportation sector but also the growers and farming community.

"Recalcitrance, or a plant's natural defenses against insects, fungus and the weather, is widely acknowledged as being the single biggest barrier to the production of and biochemicals from switchgrass and other lignocellulosic materials," said Jonathan Mielenz, a co-author and member of the Department of Energy lab's Science Center.

For years researchers have sought better ways to break down the plant's defense system, and while substantial progress has been reported, recalcitrance remains a significant challenge.

Despite this obstacle, switchgrass holds great promise as a bioenergy because it is a native perennial plant, grows with high yields and requires little nitrogen and water. These characteristics made it an attractive target for transgenic improvements.

To achieve their goal, a team led by Zeng Yu Wang of The Samuel Roberts Noble Foundation in Ardmore, Okla., chose to "downregulate" – a process that involves decreasing a cellular component – the caffeic acid 3-O-methyltransferase, or COMT, gene – in the Alamo variety of switchgrass. This change decreased the plant's structural "glue," lignin, by about one-eighth. The scientists chose this gene based on encouraging results of lignin modification from previous Noble research conducted in alfalfa and other plant species.

What the team from the Noble Foundation ended up with, as discovered by a team led by Mielenz, is a switchgrass that is more easily converted to biofuels under milder conditions and with much lower costly additions during fermentation.

"The presence of lignin in plant cell walls interferes with the fermentation to produce biofuels," said Wang, who noted that enzymes are the single largest processing cost component for bioconversion of biomass after the biomass itself. "The transgenic lines require lower temperature preprocessing and only one-quarter to one-third the level of enzymes for equivalent ethanol fermentation compared to the unmodified switchgrass. This significantly lowers the cost of biofuels and biochemicals from this switchgrass."

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More information: The paper, titled "Genetic manipulation of lignin reduces recalcitrance and improves ethanol production from switchgrass," will be published online this week.

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User comments : 5

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apex01
not rated yet Feb 14, 2011
More money should be spent on algae biofuel R&D. There's far more potential there than anywhere else.
kaasinees
not rated yet Feb 14, 2011
Yeah fuel produced by microbes and pyrolysis are definitly the future of a sustainable societity.
TheGhostofOtto1923
3.7 / 5 (3) Feb 14, 2011
Too bad you couldn't engineer them to produce their own digestive enzymes somehow? Perhaps in an inert precursor form which could be converted much more cheaply during processing, than adding the enzymes themselves?
Doug_Huffman
not rated yet Feb 14, 2011
switchgrass boosts biofuel yield by more than one-third
1350 Watts per square meter, nevermore!
Pkunk_
not rated yet Feb 15, 2011
switchgrass boosts biofuel yield by more than one-third
1350 Watts per square meter, nevermore!


Low maintenance and Low cost but.. One of the beauties of self replicating systems unlike solar energy.