By Anna Lynn Spitzer
Irvine, Calif., April 2009 -- Ethanol could be the grand prize in the U.S.’s race for environmentally neutral energy independence. It derives from
natural products like corn and sugar cane, and is high-octane, clean-burning and renewable.
But there’s a hitch. It is expensive to manufacture and leaves a carbon footprint during processing. In addition, the U.S. produces most of its
ethanol from corn, leading to agricultural repercussions that include increased corn prices, higher prices for livestock feed and many foods, and extensive acreage requirements to grow the crop.
UCI scientists, however, are well on the way to solving those
problems. They are creating a yeast strain that can produce twice as
much ethanol naturally from a wide variety of new biomaterials.
New Gene, New Capability
Using computational biology techniques, they are modifying the genetic structure of a common yeast strain called Saccharomyces, which produces ethanol as a byproduct when it ferments plant sugars. One of those sugars is glucose, which Saccharomyces easily breaks down because the yeast produces the necessary enzymes.
But plant material contains other sugars as well, namely xylose and arabinose, which Saccharomyces cannot process. Researchers knew that E. coli produces the enzymes necessary to break down arabinose, so they isolated the correct protein sequence from the bacteria. Then they re-engineered its gene with their patented gene protein-production technology so that it would successfully express in Saccharomyces, inserted it into the yeast’s old chromosome, and voila!
Now Saccharomyces can break down arabinose effectively.
They are doing similar work with genes from other fungi that are growing successfully on xylose.
The new and improved yeast will be able to ferment sugars found in other forms of biomass like switchgrass, hemp, wheat stalks and wood, expanding greatly the stockpile of materials from which ethanol can be gleaned.
It can also circumvent expensive production techniques. The modified yeast strains are being engineered to grow anaerobically, so
they don’t need air to function. This eliminates the need to pump oxygen in during fermentation, an expensive process that also
increases the risk of contamination.
Reducing Production Costs
If all goes according to plan, project leader Wes Hatfield, director of Calit2’s Computational Biology Research Laboratory, believes the mutated yeast can double the efficiency of ethanol production without diverting food from humans or animals.
“Right now, the cheapest ethanol is $2.90/gallon to make. If we can get this to work under anaerobic conditions, which will increase the yield, we could double the ethanol production rate,” says Hatfield. “That would be like cutting the cost of a gallon of fuel in half.”
The project is a multi-pronged effort that encompasses researchers from the CBRL, and the schools of information and computer sciences, engineering and medicine, as well as industry partner Verdezyne, Inc., an Orange County synthetic biology company, which under its former name, CODA Genomics, was created from UCI research. The project is supported by Verdezyne and a two-year UC Discovery Grant that provides matching funds for innovative industryuniversity research partnerships.
“One of the real stories of the biofuel research has been the collaboration of disparate groups across campus and getting the synergism that we really hadn’t had before,” says Hatfield, who is also UCI professor emeritus and a co-founder of CODA Genomics.
He says it’s a “better than even bet” that the biofuel project will succeed. Next steps include ordering fermenters and putting the new yeast organisms through their paces. “At the end of the grant, we hope to have an organism that we can turn over to industry for pilot plant optimization.”