New Enzymes Boost Alcohol Production

What do ethanol, baked goods and beer have in common? These products, and the industries that make them, are among the latest beneficiaries of studies conducted by the Agricultural Research Service (ARS), the U.S. Department of Agriculture's chief scientific research agency.

ARS plant physiologist Cynthia Henson and colleagues in the agency's Cereal Crops Research Unit at Madison, Wis., have designed three heat-loving barley enzymes that perform exceptionally well at temperatures hovering above 70 degrees Celsius, or about 160 degrees Fahrenheit.

Thanks to their distinctive heat tolerance, these barley enzymes can yield up to 30 percent more sugar than enzymes found in conventional barley lines. More sugar means more fermentable product for brewing beer—and more sugar for converting into ethanol-based fuels.

A premium barley line is not only great news for industry, it's also a boon to the nation's barley growers, who earn up to a dollar more per bushel for top-of-the-line barley varieties suited for ethanol and beer production.

Today's barley enzymes become severely sluggish when they're thrust into superheated temperatures. But while the heat dulls the enzymes' catalyzing abilities, it is a necessary evil. It's vital for loosening up the barley's starches and readying them for conversion into sugar.

For example, at high temperatures, alpha-glucosidase—one of the most important barley enzymes for turning starches into fermentable sugars during beer-making—has less than 5 percent of the activity it normally would.

Hopefully, that's about to change. With Henson's discovery, barley plants containing the new-and-improved enzymes may only be a couple of years away.

The enzymes weren't developed for breeding into current barley plants. Instead, the researchers are using them as a search tool to scan vast collections of barley plants for accessions already possessing the desirable enzymes.

With so much genetic diversity to sift through and mine, Henson says it's probable that the impressive heat-tolerant enzymes are out there. They just need to be discovered.

Read more in the September 2006 issue of Agricultural Research magazine.