After decades of studying a plant gene, scientists from the United States Department of Energy's BioEnergy Science Center have discovered it can be manipulated to streamline the biofuel production process, ultimately leading to lower ethanol costs.

The researchers from B.E.S.C., led by Steven Brown of the energy department's Oak Ridge National Laboratory, identified a key gene in the microbe Clostridium thermocellum that allows it to tolerate high concentrations of ethanol.

Clostridium thermocellum is a microorganism that produces its own enzymes that can break down cellulose and ferment plant sugars into ethanol.

Currently, biofuel production uses expensive enzymes to do the same thing. Additionally, these enzymes tend to break down in ethanol rendering them useless after one use.

"If we can evolve the strain to be more tolerant to ethanol, the hope is that we could make higher concentrations of ethanol, which would lower biofuel production costs," said Mr. Brown.

Incorporating these microorganisms into biofuel production, could streamline the process and result in lowered biofuel production costs.

"We want the microbe to make more lignocellulosic ethanol, so were trying to understand the genetic basis behind the process," said Mr. Brown.

The B.E.S.C. team located the key gene by sequencing the genomes of two types of C. thermocellum, one being an ethanol-adapted strain.

The researchers singled out a mutated gene in this ethanol-adapted strain called alcohol dehydrogenase, the final protein in the microbes pathway for making ethanol.

"When we put this particular copy of the adhE gene into the wild type strain, we were able to generate the mutant phenotype with just this one gene," explained Mr. Brown.

The discovery comes in time as U.S. ethanol prices hit a three-year record-high last June, rising by 7 cents to $2.75 a gallon in the Midwest.

At the same time, the U.S. Department of Agriculture anticipates corn harvests to reach an all-time low in 15 years, with harvests reduced by 2 percent. Since corn is the primary source of ethanol in the U.S., the gene discovery can aid in developing alternative sources to corn ethanol.

The teams findings were published in the Proceedings of the National Academy of Sciences as "Mutant alcohol dehydrogenase leads to improved ethanol tolerance in Clostridium thermocellum." The invention is now available for licensing.

The B.E.S.C. operates under the Oak Ridge National Laboratory and supports multidisciplinary and multi-institutional research on the production of cellulosic biofuels, or biofuels from nonfood plant fiber. (Jen Balboa)

source: APEC-VC Korea