Single microbial gene linked to increased ethanol tolerance

August 15, 2011 By Morgan McCorkle
Researchers at ORNL's BioEnergy Science Center have identified a single gene -- represented in this protein structure visualization -- that is responsible for ethanol tolerance in C. thermocelllum. More ethanol-tolerant strains of the microbe could boost ethanol production from woody crops. Credit: T Splettstoesser,

( -- A team of researchers from the Department of Energy's BioEnergy Science Center has pinpointed a single, key gene in a microbe that could help streamline the production of biofuels from non-food sources.

Led by Steven Brown of DOE's Oak Ridge National Laboratory, the team identified a key gene responsible for ethanol tolerance in Clostridium thermocellum, a microorganism under consideration for use in a new biofuel production technique called consolidated bioprocessing, or CBP.

Current methods to make from lignocellulosic biomass -- or , for example -- require the addition of expensive enzymes to break down raw materials. In a more streamlined approach, CBP uses microorganisms that produce their own enzymes to liberate the plant's sugars and ferment them into ethanol.

"We want the microbe to make more lignocellulosic ethanol, so we're trying to understand the genetic basis behind the process," Brown said. "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 costs."

Although scientists have studied the C. thermocellum microbe for decades, the for its ability to tolerate higher concentrations of ethanol had not been determined. Earlier studies indicated that multiple genes, instead of a single allele, likely caused ethanol tolerance.

"Our results were really unexpected," Brown said. "It was deemed very unlikely to be a single gene because it's such a complex trait."

The BESC team located the single gene by sequencing the genomes of two types of C. thermocellum -- a wild-type strain as a reference and an ethanol-adapted strain. The researchers singled out a mutated gene in the ethanol-adapted strain called alcohol dehydrogenase, the final protein in the microbe's 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," Brown said.

Further analysis including protein structural modeling provided a more complete picture of the mutant gene.

"It's a very comprehensive study," said Paul Gilna, director of BESC. "Rather than have just one technique or one approach, we were able to draw upon multiple experts within their fields to contribute a broader set of analyses. It is a great example of how a center such as BESC can apply expertise from multiple disciplines to bear on research questions such as this."

Explore further: Scientist IDs genes that promise to make biofuel production more efficient, economical

More information: The team's results 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 available for licensing.

Related Stories

Displacing petroleum-derived butanol with plants

January 8, 2009

As a chemical for industrial processes, butanol is used in everything from brake fluid, to paint thinners, to plastics. According to a University of Illinois researcher, butanol made from plant material could displace butanol ...

Recommended for you

Study shows how giraffe assassin bugs outwit spider prey

October 26, 2016

(—A biologist at Macquarie University in Australia has discovered the secret behind the giraffe assassin's ability to catch and kill spiders in their webs. In his paper published on the open access site Royal Society ...

New analysis of big data sheds light on cell functions

October 26, 2016

Researchers have developed a new way of obtaining useful information from big data in biology to better understand—and predict—what goes on inside a cell. Using genome-scale models, researchers were able to integrate ...

Researchers identify genes for 'Help me!' aromas from corn

October 25, 2016

When corn seedlings are nibbled by caterpillars, they defend themselves by releasing scent compounds that attract parasitic wasps whose larvae consume the caterpillar—but not all corn varieties are equally effective at ...

Genome editing: Efficient CRISPR experiments in mouse cells

October 25, 2016

In order to use the CRISPR-Cas9 system to cut genes, researchers must design an RNA sequence that matches the DNA of the target gene. Most genes have hundreds of such sequences, with varying activity and uniqueness in the ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.