Microbes Engineered to Create Affordable Biofuel

Creating affordable transportation fuels from biomass is a goal scientists have longed to achieve. Now, thanks to new research from the University of Georgia (UGA) who taught a certain microbes to make the conversion, this dream may soon become a reality.

Using biomass as a means of creating fuel has been an expensive process because of the required pretreatment of biomass feedstock - a hurdle that has hindered fuel production. Pretreatment involves breaking down plant cell walls before fermentation into ethanol.

But researchers, led by Janet Westpheling, a professor in the Franklin College of Arts and Sciences department of genetics, engineered the bacterium Caldicellulosiruptor bescii to circumvent this pretreatment process so biomass could directly be transformed into biofuel.

"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 in a UGA news release. "This is the first step toward an industrial process that is economically feasible."

The team developed 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. That's not to say that this was an easy step.

"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," Westpheling explained.

Caldicellulosiruptor bacteria are found in several isolated areas around the world, from a hot spring in Russia to Yellowstone National Park.

Researchers have engineered the bacteria to yield ethanol, but it can also be taught to produce other similar transportation fuels such as butanol and isobutanol.

"To take a virtually unknown and uncharacterized organism and engineer it to produce a biofuel of choice within the space of a few years is a towering scientific achievement for Dr. Westpheling's group and for BESC," applauded Paul Gilna, director of the BioEnergy Science Center.

The findings are published in the journal Proceedings of the National Academy of Sciences.