Microbes engineered for the direct conversion of biomass to ethanol fuel
Date: 3.6.2014
The promise of affordable transportation fuels from biomass—a sustainable, carbon neutral route to American energy independence—has been left perpetually on hold by the economics of the conversion process.
New research from the University of Georgia has overcome this hurdle allowing the direct conversion of switchgrass to fuel. The study, published in the Proceedings of the National Academy of Sciences, documents the direct conversion of biomass to biofuel without pre-treatment, using the engineered bacterium Caldicellulosiruptor bescii.
Pre-treatment of the biomass feedstock—non-food crops such as switchgrass and miscanthus—is the step of breaking down plant cell walls before fermentation into ethanol. This pre-treatment step has long been the economic bottleneck hindering fuel production from lignocellulosic biomass feedstocks.
Janet Westpheling, a professor in the Franklin College of Arts and Sciences Department of Genetics, and her team of researchers succeeded in genetically engineering the organism C. bescii to deconstruct un-pretreated plant biomass.
"Given a choice between teaching an organism how to deconstruct biomass or teaching it how to make ethanol, the more difficult part is deconstructing biomass," said Westpheling, who spent two and a half years developing genetic methods for manipulating the C. bescii bacterium to make the current work possible.
The UGA research group engineered a synthetic pathway into the organism, introducing genes from other anaerobic bacterium that produce ethanol, and constructed a pathway in the organism to produce ethanol directly.
