Two-for-one special: industrial enzymes and food grown in one plant
July 12, 1999
RICHLAND, Wash. –
Some crops are grown for food while others are grown to produce consumer products, but a special group of potato plants now is doing both at once. Researchers at the Department of Energy's Pacific Northwest National Laboratory have developed a specialized capability to control genes that are transplanted into a plant. Researchers are able to direct desirable traits into a specific portion of a plant, allowing dual-use of one crop.
The experimental potatoes have sprouted valuable enzymes in the vines, while the tubers remain just plain old spuds to be baked, boiled or turned into french fries. These transgenic plants have been modified to produce cellulase enzymes in the foliage. The cellulase-producing genes were isolated from bacterial and fungal organisms.
Cellulase is an enzyme used to break down plant material and is used in a wide variety of applications, from food processing to ethanol production. "The process can be adapted to create additional enzymes such as lipases and proteases used in pharmaceuticals, specialty chemical and industrial products," said Brian Hooker, a biochemical engineer at Pacific Northwest.
Currently, industrial enzymes are grown in fermenters, which is a labor- and time-intensive process that is relatively costly. Researchers say using plants as "bioreactors" to grow the enzymes is much easier and cheaper. The fermentation process costs range from $50 to $250 per gram of desired product, while Pacific Northwest estimates that growing the enzymes in plants would cost less than a penny per gram, including processing costs.
The process isn't limited just to potato plants. Other plants, especially corn, can be modified to produce enzymes in the non-edible portions. With more than 120 million dry tons of corn stalks and 4 million dry tons of potato foliage produced per year, this is an untapped resource for industrial compounds.
Additionally, the process is a boon to farmers who would be able to sell two crops for the cost of growing one. Pacific Northwest researchers estimate that by selling the potato tubers for food and vines for enzymes, farmers could increase their profits by as much as $100 to $200 per acre.
In future research, Pacific Northwest plans to use unique promoters that would induce the enzyme-producing gene in the foliage to "turn-on" after harvest. Hooker says although the Pacific Northwest process does not produce enzymes in the tuber, the public may find it more acceptable for the enzyme production to occur after the tops are separated from the potato itself.
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