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Researchers from the University of Georgia and Oak Ridge National Laboratory in Tennessee have engineered the bacterium Caldicellulosiruptor bescii, adding acetaldehyde/alcohol dehydrogenase gene to the organism so it could ferment sugars while deleting the energy-consuming lactate gene, to convert plant biomass into ethanol.

As researchers led by Janet Westpheling report in the Proceedings of the National Academy of Sciences, the engineered C. bescii, a microbe typically found in the hot springs of Yellowstone National Park, could convert 70 percent of untreated switchgrass to ethanol even though the wild-type strain cannot do the conversion at all.

ScienceInsider points out, though, that that is well below the 100 percent conversion rate of sugar to ethanol that yeast can do, but Westpheling tells them that they can probably boost the C. bescii conversion rate to 90 percent, which would then make getting ethanol from switchgrass using C. bescii cheaper than converting corn.

The researchers note that the metabolically engineered microbe could directly convert the plant biomass to ethanol, meaning that the addition of pretreatment chemicals or exogenous cellulases was not necessary as it typically is in the conversion of cellulosic biomass to ethanol.

"The idea of processing cellulosic biomass without pretreatment is an important idea," Dartmouth College's Lee Lynd, who was not involved in the study, tells ScienceInsider.