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This Genetically-Engineered Bacteria Eats Grass, Poops Out Biofuel

Scientists are getting better at making bacteria do our bidding.
June 2, 2014, 7:59pm
Image: US Department of Agriculture

One of the main problems with making biofuels such as ethanol a true alternative to gasoline is the fact that processing the stuff costs a lot of money, nullifying any sort of economic advantage you'd see over crude oil. There are other problems, of course, but the expense of the process itself is a major one. Well, a newly genetically-engineered bacteria that automates the entire process could make it dramatically easier to turn crops into fuel.

For a while, synthetic biologists have been trying to stuff genes from different bacteria into a single organism, with the hope of using the bacteria's natural biological processes to cheaply and quickly create fuels. The holy grail would be to create bacteria that can consume carbon dioxide and transform it into crude oil.

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"There's 27 chemical steps to go from Co2 to a crude oil equivalent," Joel Garreau, a futurist with the New America Foundation and researcher at Arizona State University, said last month. "At ASU we have a big biotechnology lab, and on the roof, they're growing algae, and taking these 27 chemical steps and stitching them together in one organism."

If crude oil-producing algae is the holy grail, then a new bacteria that turns grass into ethanol is at least a nice consolation prize.

Researchers at the Oak Ridge National Laboratory and the University of Georgia Department of Genetics have made it possible to take switchgrass, a grass widely grown throughout the Midwest, add some bacteria to it, and turn it directly into ethanol.

Image: PNAS

The method is both faster and, in theory, much cheaper than previous methods of turning switchgrass into biofuel, which required pretreatment with special enzymes that were so expensive as to make the entire process a waste of time.

A Popular Mechanics article from 2010 explains the problem:

"Since cellulose is tough and fibrous, it requires heavy-duty enzymatic decomposition processes to convert the plant matter into simple sugars that can be fermented into ethanol. These processes consume large amounts of energy and are so pricey that a study in Bioresource Technology last year concluded that cellulosic ethanol won't be competitive with gasoline unless oil prices remain above $90 a barrel. When that day comes, cellulosic could play a modest role in boosting supplies. And that's worth more research today. But hopes that grass clippings will end our oil habit are overblown."

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Well, oil prices are well above that, and creating switchgrass biofuel no longer requires enzymes. There are still plenty of arguments to be had about whether crop-based biofuels are actually any better for the environment than crude oil, but at the very least, they might offer some cost savings.

The bacteria in question, Caldicellulosiruptor bescii, naturally thrives in very high temperatures and has been known to break down cellulose, which was considered the most difficult part of turning switchgrass into fuel. Janet Westpheling, a researcher at the University of Georgia, took the bacteria, gave it genes from other bacteria that can produce ethanol, and the whole system just worked.

"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 toward an industrial process that is economically feasible."

Despite switchgrass' prior economic failures, there's still some big money behind it. The US government funded Westpheling's study, which was published in Proceedings of the National Academy of Sciences, and the Navy is developing a switchgrass-based jetfuel that will one day power its fighter jets.

With expensive genetic engineering out of the way, Westpheling's bacteria can be bred in the lab, and pretty soon they could be creating biofuel en masse.