OAK RIDGE, Tenn., Feb. 16, 2012 — Studies of bacteria first found in Yellowstone's hot springs are furthering efforts at the Department of Energy's BioEnergy Science Center toward commercially viable ethanol production from crops such as switchgrass.

As explained by a press release from Oak Ridge National Laboratory, the current production of ethanol relies on the use of expensive enzymes that break down complex plant materials to yield sugars that are fermented into ethanol. One suggested cheaper alternative is consolidated bioprocessing, a streamlined process that uses microorganisms to break down the resistant biomass.

"Consolidated bioprocessing is like a one-pot mix," said Oak Ridge National Laboratory's Richard Giannone. "You want to throw plant material into a pot with the microorganism and allow it to degrade the material and produce ethanol at the same time."

The BESC study focused on Caldicellulosiruptor obsidiansis, a naturally occurring bacterium discovered by BESC scientists in a Yellowstone National Park hot spring. The microorganism, which thrives at extremely high temperatures, breaks down organic material such as sticks and leaves in its natural environment, and scientists hope to transfer this capability to biofuel production tanks.
 

In a paper featured on the cover of the Journal of Proteome Research, the BESC team conducted a comparative analysis of proteins from C. obsidiansis grown on four different carbon sources, ranging from a simple sugar to more complex substrates such as pure cellulose and finally to switchgrass. The succession of carbon substrates allowed researchers to compare how the organism processes increasingly complex materials. The researchers found that growth on switchgrass prompted the organism to express an expanded set of proteins. 

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"By comparing how C. obsidiansis reacted to switchgrass, relative to pure cellulose, we were able to pinpoint the specific proteins and enzymes that are important to plant cell wall deconstruction—a major roadblock to the production of advanced biofuels," Giannone said.

The team is able to combine several approaches to the study of these proteins that will better equip researchers to make recommendations about their use in ethanol production.

Coauthors on the paper are Hamburg University of Technology's Adriane Lochner and Garabed Antranikian, and ORNL's Martin Keller, David Graham and Robert Hettich. The full publication is available here: http://pubs.acs.org/doi/abs/10.1021/pr200536j.

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