Some corn has a new ingredient. It's an enzyme, amylase, that breaks down corn starch into sugars to make ethanol.
The corn amylase trait was developed by Syngenta, which hopes to launch the trait to growers in 2008, pending further regulatory, technical and commercial tests. The genetically modified strain of corn expresses high levels of alpha amylase-T, a heat-tolerant enzyme that digests corn's starch into sugar for ethanol. Amylase must be selected to withstand the 203-302° cooking temperatures that dissolve the starch in the dry grind process.
This enzyme is otherwise added separately to the dry grind ethanol process. It's expected that providing this enzyme in corn will increase ethanol plant efficiency.
“This trait delivers more than direct substitution,” says Bruce Howison, Syngenta head of marketing, corn and soybean traits.
Syngenta spokesman Tom Gahm explains, “We believe that there are potentially a number of ways in which corn amylase will improve the entire process of ethanol production, beyond merely replacing existing forms of amylase. We look forward to testing this on a commercial scale pending USDA and FDA registration approvals.”
A recent National Academy of Sciences study (www.pnas.org) reports that corn-based ethanol provides 25% more energy than the energy invested in the fertilizer, fuel and transportation used to produce ethanol. The newest ethanol-friendly hybrids will optimize this conversion, says Ron Phillips, University of Minnesota corn geneticist and member of the National Academy of Science.
Viewed microscopically, corn contains two starches, one branched in structure and one “straight chain.” The amylase enzyme digests the second starch, amylose, into sugars that are distilled into ethanol. By building this enzyme into the seed, it's low cost, readily available and speeds up the dry grind process, Phillips says.
In nature, the corn plant releases amylase during germination, says Vern Cardwell, University of Minnesota professor of Agronomy and Plant Genetics.
