Cow stomach microbe holds key to turn corn plants into biofuel

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London, April 9 : Researchers at the Michigan State University have discovered that an enzyme from a microbe, which lives inside a cow's stomach is the key to turn corn plants into biofuel.

They found that the enzyme, which allows a cow to digest grasses and other plant fibres, could be used to turn other plant fibres into simple sugars. These simple sugars help in producing ethanol to power cars and trucks.

And researchers have identified 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. 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," Nature quoted Mariam Sticklen, MSU professor of crop and soil science, as saying.

With the help of bacteria, cows convert plant fibres, called cellulose, into energy, but this is a big step for biofuel production.

Usually, in the commercial biofuel industry, only the kernels of corn plants could be used to make ethanol, but this new discovery will let the entire corn plant to be used, leading to more fuel production with less cost.

There are three enzymes, which help turn plant fibres into sugar. 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.

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

The second version, 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.

And the third version, 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. Without it they can't convert the waste into ethanol without buying enzymes - which is expensive," Sticklen said.

The Spartan Corn line was created with the help of an animal stomach microbe gene, which was inserted into a plant cell. The DNA assembly of the animal stomach microbe required heavy modification in the lab to make it work well in the corn cells.

Researchers compared the process to adding a single Christmas tree light to a tree covered in lights.

"You have a lot of wiring, switches and even zoning. There are a lot of changes. We have to increase production levels and even put it in the right place in the cell," Sticklen said.

In case the cell produced the enzyme in the wrong place, the plant cell would not be able to function, and, instead, it would digest itself. And that is the reason why Sticklen found a specific place to insert the enzyme.

One of the targets for the enzyme produced in Spartan Corn III is a special part of the plant cell, called the vacuole, which is a safe place to store the enzyme until the plant is harvested. The enzyme will collect in the vacuole with other cellular waste products.

Because it is only in the vacuole of the green tissues of plant cells, the enzyme is only produced in the leaves and stalks of the plant, not in the seeds, roots or the pollen. It is only active when it is being used for biofuels because of being stored in the vacuole.

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

She is presenting at the 235th national American Chemical Society meeting in New Orleans today.

The work also is presented in the June edition of Nature Review Genetics.

ANI

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