Engineered microbes convert biomass to fuel

Scientists have genetically engineered microbes to successfully convert biomass into fuel directly, in a first step towards industrial production.
A new research by the University of Georgia 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.

She spent two and a half years developing genetic methods for manipulating the C bescii bacterium to make the current work possible.
Researchers 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.
"Now, without any pretreatment, we can simply take switchgrass, grind it up, add a low-cost, minimal salts medium and get ethanol out the other end," Westpheling said.

"This is the first step towards an industrial process that is economically feasible," she said.
The study was published in the journal PNAS.