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Bacteria rebuilt to make oil

Eric Steen / JBEI
E. coli bacteria were genetically engineered to produce oil, then sequester
themselves from the droplets to facilitate oil recovery, as shown in this photo.

Researchers have engineered a common type of bacteria to produce biodiesel and other goodies from plain old plants. The microbial trickery, detailed today in the journal Nature, promises to add "nature's petroleum" to America's energy supply within the next few years.

"We've got a billion tons of biomass every year that goes unused," said Jay Keasling, a co-author of  research study and chief executive officer for the U.S. Department of Energy's Joint BioEnergy Institute, or JBEI. "We'd like to turn that into fuel."

"Biomass" is shorthand for any plant material that's suitable for converting into energy, ranging from grain to the stuff that's left behind in the field after harvesting, from wood product waste to plants and seeds. Corn, for instance, is the primary source of biomass for making ethanol in the United States.

The problem with corn is that its use for energy production competes with its use for food. That's why scientists are devoting so much time and brainpower to developing methods for converting indigestable cellulose (like wood chips) into fuel.

Keasling and his colleagues say their bioengineered E. coli bacteria could provide an affordable path to greater energy independence. Theoretically, the fuel produced from biomass could make up for as much as 50 percent of U.S. oil imports. "We want to turn the U.S. Midwest into the new 'Mideast,'" Keasling said.

The Nature article explains how E. coli could do it: Researchers modified the bacteria's genome to insert the coding for producing an enzyme known as hemicellulase. That enzyme can break down one of the ingredients of cellulosic feedstock, hemicellulose, into smaller sugar molecules.

E. coli bacteria are naturally programmed to turn those sugars into fatty acids for building cell membranes - but normally, each bacterium produces only as much of the fatty acids as it  needs. Rsesearchers fiddled with that part of the genetic code, too. "We stole away the fats it would normally use to make the membrane and channeled them into biodiesel instead," Keasling said.

That essentially turned the bacteria into little biodiesel factories. "The more you steal away, the more it turns it up," Keasling said.

The bacteria expelled droplets of oil into the fermentation vats, which made extraction of the fuel relatively easy. "When you turn the impellers off, it's like oil and water," Keasling explained. "The oil floats to the top, you skim it off, you put it in your tank."

The process could be tweaked to produce other chemical products as well, ranging from jet fuel to solvents and lubricants.

Keasling emphasized that the study published in Nature was a "proof of concept" rather than the demonstration of a commercially viable process. He and his colleagues are looking for a process that would utilize as much of the feedstock as possible, and not just the hemicellulose. "We got about 10 percent of the theoretical maximum yield, and we will continue to work on this to try to increase the yield," he said.

One of the funders for the research is LS9, a California-based biotech company that intends to market fuels and other microbe-produced chemicals. "I'm reasonably optimistic that we're going to have high-level production of these kinds of biofuels in the next couple of years," Keasling said. Check out this Berkeley Lab news release to learn more about the research.

LS9 isn't the only venture in the bacterial biofuel business. Researchers at the University of California at Los Angeles and a different company named Gevo have devised a different technique for turning E. coli into biobutanol factories. Yet another company, Amyris Biotechnologies, recently received millions of dollars in federal funding to turn sorghum into biofuels using genetically modified yeast.

All these ventures are aiming to get biofuel products on the market in the next few years. But which company will be the first? Which will be the best? Feel free to weigh in on the future of microbe-based energy production by leaving your comments below.

Update for 8:45 p.m. ET: The latest feats from E. coli come as no surprise to Carl Zimmer, who literally wrote the book on the humble bacterium. This week in his blog, The Loom, he asks a rhetorical question: "Is there nothing E. coli cannot do?"

Update for 10 p.m. ET: Here's a Tech Review article about LS9 from its start-up phase in 2007. There was a lot of talk about "clean energy" in President Barack Obama's first State of the Union address tonight, including advanced biofuels, but the true energy revolution will come about only when technology can produce fuels that are efficient, clean - and, above all, affordable. Will bioengineered bacteria help cure what ails America's energy economy? Stay tuned.