Cow enzyme inserted into corn plants and presto, whole thing yields biofuel

EAST LANSING, Mich. — An enzyme from a microbe that lives inside a cow’s stomach is the key to turning corn plants into fuel, according to Michigan State University scientists.

The enzyme that allows a cow to digest grasses and other plant fibers can be used to turn other plant fibers into simple sugars. These simple sugars can be used to produce ethanol to power cars and trucks.

Michigan State University scientists have discovered a way to grow corn plants that contain this enzyme. They have inserted a gene from a bacterium that lives in a cow’s stomach into a corn plant.

Conversion

Now, the sugars locked up in the plant’s leaves and stalk can be converted into usable sugar without expensive synthetic chemicals.

“The fact that we can take a gene that makes an enzyme in the stomach of a cow and put it into a plant cell means that we can convert what was junk before into biofuel,” said Mariam Sticklen, Michigan State University professor of crop and soil science.

She presented at the 235th national American Chemical Society meeting in New Orleans recently. The work also is presented in the Plant Genetic Engineering for Biofuel Production: Towards Affordable Cellulosic Ethanol in the June edition of Nature Review Genetics.

Cows, with help from bacteria, convert plant fibers, called cellulose, into energy, but this is a big step for biofuel production.

Entire plant

Traditionally in the commercial biofuel industry, only the kernels of corn plants could be used to make ethanol, but this new discovery will allow the entire corn plant to be used — so more fuel can be produced with less cost.
Turning plant fibers into sugar requires three enzymes. The new variety of corn created for biofuel production, called Spartan Corn III, builds on Sticklen’s earlier corn versions by containing all three necessary enzymes.

The first version, released in 2007, cuts the cellulose into large pieces with an enzyme that came from a microbe that lives in hot spring water.

How it works

Spartan Corn II, with a gene from a naturally occurring fungus, takes the large cellulose pieces created by the first enzyme and breaks them into sugar pairs.

Spartan Corn III, with the gene from a microbe in a cow, produces an enzyme that separates pairs of sugar molecules into simple sugars. These single sugars are readily fermentable into ethanol, meaning that when the cellulose is in simple sugars, it can be fermented to make ethanol.

“It will save money in ethanol production,” Sticklen said. “Without it they can’t convert the waste into ethanol without buying enzymes — which is expensive.”

“Spartan Corn III is one step ahead for science, technology and it is even a step politically,” Sticklen said. “It is one step closer to producing fuel in our own country.”