Spartan Corn Grows Enzymes
Corn growers in the future may not only raise corn and biomass for ethanol but also the enzymes, all in the same plant.
Enzyme-carrying corn germ-plasm has been developed by researchers at Michigan State University (MSU) and appropriately named Spartan, after the school's moniker. In a cellulosic ethanol process, the Spartan-carrying corn stover would be pulped, and the liquid containing the enzymes would be extracted, says researcher Mariam Sticklen. The stover would go through pretreatment to free the cellulose and hemicellulose from the lignin, and then be reunited with the enzyme-bearing fluid for fermentation, reducing costs for industrial enzymes.
Spartan corn germplasm has been genetically engineered to express cellulase and hemicellulase in the plant's leaves and stover, explains Sticklen, an MSU professor of crop and soil sciences. The first generation Spartan 1 contains E-1 endoglucanase, which can break down cellulose into simpler sugars for fermentation. Spartan 2 also includes the enzymes beta-glucosidase, hemicellulase and ligninase. Spartan 3 is currently being developed. "We're modifying the lignin chemical structure, so it will break down with a very mild pretreatment," she says.
Spartan 1 has been tested, published and patented. Over 10 companies have shown an interest in licensing the germplasm technology from the university. Once the licensing agreements are worked out, the germplasm will be bred into corn inbred lines. Depending on the aggressiveness of the licensing companies, it will be a couple of years or more for new hybrids to be tested in field trials and the seed increased to become commercially available to growers. Spartan 2 is a step behind, with its testing and patent complete, and the final publication of the work being completed. Spartan 3 has two or three years of work left at Sticklen's labs. The material has been isolated and a patent filed, and testing is underway to select two or three specimens that have the trait to modify the lignin "without harm to the plant material," she says. "The stems continue to have structural integrity and resistance to pathogens and insects."
She continues, "The interesting thing about our technology is the safety of our material." The protein (enzyme) is stored within the leaf and stem cell walls. It isn't involved in the plant's metabolic activity; thus, the enzyme isn't found in the kernels of corn, the roots or pollen. Stover remaining in the field will degrade a bit faster than normal since it already carries the enzymes manufactured by soil bacteria and fungi to degrade the plant residues. The genetic material used in the new germplasm originated in those soil microbes. In Spartan 3 corn, concerns about pollen drift and unwanted genetic crosses are eliminated because in the MSU technology the transgenes are carried within the chloroplast, Sticklen says. "Everything stays within the maternal tissue, so no pollen grain will carry the genes or the traits," she explains.
Enzyme-carrying corn germ-plasm has been developed by researchers at Michigan State University (MSU) and appropriately named Spartan, after the school's moniker. In a cellulosic ethanol process, the Spartan-carrying corn stover would be pulped, and the liquid containing the enzymes would be extracted, says researcher Mariam Sticklen. The stover would go through pretreatment to free the cellulose and hemicellulose from the lignin, and then be reunited with the enzyme-bearing fluid for fermentation, reducing costs for industrial enzymes.
Spartan corn germplasm has been genetically engineered to express cellulase and hemicellulase in the plant's leaves and stover, explains Sticklen, an MSU professor of crop and soil sciences. The first generation Spartan 1 contains E-1 endoglucanase, which can break down cellulose into simpler sugars for fermentation. Spartan 2 also includes the enzymes beta-glucosidase, hemicellulase and ligninase. Spartan 3 is currently being developed. "We're modifying the lignin chemical structure, so it will break down with a very mild pretreatment," she says.
Spartan 1 has been tested, published and patented. Over 10 companies have shown an interest in licensing the germplasm technology from the university. Once the licensing agreements are worked out, the germplasm will be bred into corn inbred lines. Depending on the aggressiveness of the licensing companies, it will be a couple of years or more for new hybrids to be tested in field trials and the seed increased to become commercially available to growers. Spartan 2 is a step behind, with its testing and patent complete, and the final publication of the work being completed. Spartan 3 has two or three years of work left at Sticklen's labs. The material has been isolated and a patent filed, and testing is underway to select two or three specimens that have the trait to modify the lignin "without harm to the plant material," she says. "The stems continue to have structural integrity and resistance to pathogens and insects."
She continues, "The interesting thing about our technology is the safety of our material." The protein (enzyme) is stored within the leaf and stem cell walls. It isn't involved in the plant's metabolic activity; thus, the enzyme isn't found in the kernels of corn, the roots or pollen. Stover remaining in the field will degrade a bit faster than normal since it already carries the enzymes manufactured by soil bacteria and fungi to degrade the plant residues. The genetic material used in the new germplasm originated in those soil microbes. In Spartan 3 corn, concerns about pollen drift and unwanted genetic crosses are eliminated because in the MSU technology the transgenes are carried within the chloroplast, Sticklen says. "Everything stays within the maternal tissue, so no pollen grain will carry the genes or the traits," she explains.
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