Scientists at the Department of Energy’s BioEnergy Science Center (BESC) have taken a huge step towards the possibility of enhancing ethanol production following their discovery of a mutated gene that improves ethanol tolerance in microorganisms. This finding could have implications in our ability to meet alternative energy challenges associated with nonrenewable fuels. The research is published in the August 16 issue of the Proceedings of the National Academy of Sciences.

Previous reports have suggested that ethanol tolerance in the alcohol fermenting bacterium, Clostridium thermocellum, is related to alterations in membrane proteomic profiles of wild-type (WT) versus ethanol-adapted (EA) strains. However, the genetic basis for ethanol tolerance in EA strains had not been determined until this study. The BESC researchers therefore hypothesized that one or more mutations in the genome of C. thermocellum EA strains allow it to survive at higher ethanol concentrations than the WT strain. To their surprise, a single mutant gene known as acetaldehyde-CoA/alcohol dehydrogenase (adhE) was found to be responsible for this trait.

The discovery of the gene controlling ethanol production in C. thermocellum will mean that scientists can now experiment with genetically altering biomass plants to produce more ethanol. Current methods to make ethanol from a type of biomass found in switchgrass and agricultural waste require the addition of expensive enzymes to break down the plant's barriers that guard energy-rich sugars. Scientists, including those at BESC, have been working to develop a more streamlined approach in which tailor-made microorganisms produce their own enzymes that unlock the plant's sugars and ferment them into ethanol in a single step. Identifying this gene is a key step towards making the first tailor-made microorganism that produces more ethanol.

Rather than using just one technique or one approach, the research team that made the discovery was able to draw upon multiple experts spanning several scientific disciplines to contribute a broader set of analyses because of the BESC partnership.

BESC is led by Oak Ridge National Laboratory and is one of three DOE Bioenergy Research Centers established by the DOE's Office of Science in 2007. The centers support multidisciplinary, multi-institutional research teams pursuing the fundamental scientific breakthroughs needed to make production of cellulosic biofuels, or biofuels from nonfood plant fiber, cost-effective on a national scale.

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Full original research article available here.