Janet Westpheling at the University of Georgia (UG) has engineered microbes allowing the direct conversion of switchgrass to ethanol.

Janet Westpheling in her lab at the University of Georgia.  Image Credit: UG,  Click image for the largest view.

Janet Westpheling in her lab at the University of Georgia. Image Credit: UG. Click image for the largest view.

Her study paper was published in the Proceedings of the National Academy of Sciences, documenting the direct conversion of biomass to ethanol without a pre-treatment, using the engineered bacterium Caldicellulosiruptor bescii.

Hopes for affordable transportation fuels from biomass with a sustainable, carbon neutral route to American energy independence has been held up by the economics of the biomass conversion process. We’ve seen a lot, sugarcane and corn ethanol which works, various heating methods that remain uneconomic and vast array of organisms trying to make fuels from sunlight and an assortment of carbon sources. So far, industrial scale has only seen sugarcane and corn ethanol go to market in a big way and due to detractors is getting stuck in place from an impressive disinformation campaign.

Pre-treatment of the biomass feedstock 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. The UG team has been working on non-food crops such as the highly productive switchgrass and miscanthus species.

Now Professor Westpheling, at the Franklin College of Arts and Sciences department of genetics, and her team of researchers who are all members of U.S. Department of Energy-funded BioEnergy Science Center in which UG is a key partner have succeeded in genetically engineering the organism C. bescii to deconstruct un-pretreated plant biomass.

Professor Westpheling, who spent two and a half years developing genetic methods for manipulating the C. bescii bacterium to make the current work possible said, “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.”

The UG 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.

Sitting down? Westphaling explained, “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. This is the first step toward an industrial process that is economically feasible.”

That’s even more simple than the sugarcane and corn ethanol process by a bit.

The difficulty of using plant biomass for the production of fuels is a resistance to microbial degradation evolved in plants over millions of years. The plant’s defenses results from their rigid cell walls that have been the key to their survival and the major impediment to biofuel production. Understanding the scientific basis of, and ultimately eliminating the difficult recalcitrance as a barrier has been the core mission of the UG BioEnergy Science Center.

The third party comment, “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,” comes from Paul Gilna, director of the BioEnergy Science Center, headquartered at Oak Ridge National Laboratory. “It is a true reflection of the highly collaborative research we have built within BESC, which, in turn, has led to accelerated accomplishments such as this,” he added.

Caldicellulosiruptor bacteria have been isolated around the world at locations such as a hot spring in Russia to Yellowstone National Park. Westpheling explained that many microbes in nature demonstrate prized capabilities in chemistry and biology but that developing the genetic systems to use them is the most significant challenge.

“Systems biology allows for the engineering of artificial pathways into organisms that allow them to do things they cannot do otherwise,” she said.

Ethanol is but one of the products the bacterium can be taught to produce. Others include butanol and isobutanol (transportation fuels comparable to gasoline with more carbon in larger molecules), as well as other fuels and chemicals using biomass as an alternative to petroleum.

“This is really the beginning of a platform for manipulating organisms to make many products that are truly sustainable,” she said.

Its a hopeful breakthrough. Not discussed are the return of the nutrients to the farms and the other chemical products (mostly acetate) likely coming with the fuel product flow. The professor and her team look to have a pilot worthy process design ready. We’ll keep an eye out for their progress.


2 Comments so far

  1. B Cole on June 4, 2014 10:47 PM

    This is the first step toward an industrial process that is economically feasible.”

    I wish this could be fleshed out. Why the first step? Is there any sense this process can be commercialized? What are the hurdles?

  2. Brian Westenhaus on June 4, 2014 11:33 PM

    Go ahead, follow the links and ask Professor Westpheling. Meanwhile, having a few freshly engineered critters in a test tube is a long way from a bucket, barrel or railroad car full of them to ship to a processing facility. Will they self replicate at all? Can they ship, would they need special handling, be subject to limited travel time, can they even be concentrated without dying? Its far more complex than first imagined, and this is an extremely short list of examples. Then, some researchers get over the threshold and simply lose interest moving on to the next idea. Sugar and corn ethanol yeasts and enzymes work in an existing industry with centuries of experience and have evolved to be even more practical. Engineering a whole new critter with such practical usefulness is a huge undertaking even when the genetics will produce the result. Even then, the risks of millions, hundreds of millions or billions of (your choice of currency) on a new organism has to be met with absolute 100% certainly it will work as presented. Or it ain’t gonna happen – which is usually the case. Its simply amazing that sugar and corn ethanol exist as fuel at all and with the disinformation campaign the “sure thing” isn’t even on firm footing.

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