Spartans tailor corn for cellulosic ethanol

By Jerry W. Kram
Michigan State University (MSU) researchers have created new varieties of corn specially suited for the production of cellulosic ethanol.

Spartan corn, named after the MSU mascot, has been genetically engineered to express cellulase and hemicellulase in the plant's leaves and stover, said Miriam Sticklen, professor of crop and soil sciences. The first-generation variety contains E-1 endoglucanase, which can break down cellulose into simpler sugars for fermentation. Spartan 2, which could be released as early as 2009, will also include beta-glucosidase, hemicellulase and ligninase. It will also include modifications that will increase the amount of biomass that each plant produces. "Basically, it is the same gene used to make recombinant enzymes," Sticklen said. "Our enzymes are as efficient as enzymes produced in microbes. The difference is that when you produce it in plants, you use the energy of the sun. When you produce it in microbes, you have to add sugars, nutrients and energy for that."

In practice, the Spartan corn stover would be pulped, and a liquid containing the enzymes would be extracted, Sticklen said. The stover would then go through a pretreatment to free the cellulose and hemicellulose from the lignin, and then be reunited with the enzyme-bearing fluid for fermentation. "In our second generation, we hope there will be no need for pretreatment because we are modifying the lignin structure or there will be a minimal need for pretreatment," she said.

MSU is in talks with a number of seed companies to propagate and market Spartan corn. The first generation of Spartan corn has been patented, and patents have been filed for the second generation. The university will most likely license the varieties on a nonexclusive basis. "How far we are from commercialization is in the hands of whatever companies take the material," Sticklen said.