New enzymes boost sugar production 30%.

Ethanol, baked goods and beer are among the products that will benefit from research into new enzymes conducted by USDA-ARS scientists.

ARS plant physiologists have designed three heat-loving barley enzymes that perform exceptionally well at temperatures above 70 C. This heat tolerance enables the enzymes to yield up to 30% 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. Barley plants containing the improved enzymes may only be a couple of years away from commercial use.

A premium barley line would be a boon to the beer industry and 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's vital for loosening up the barley's starches and readying them for conversion into sugar.

Before brewing can begin, barley kernels must be malted. Heat is needed to complete the malting process, but too much heat is destructive. Two of barley's starch-degrading enzymes are heat-sensitive. One of those is the second-most-important enzyme for converting starches into fermentable sugars: alpha-glucosidase. At high temperatures, alpha-glucosidase has less than 5% of the activity it normally would. Hopefully, that's about to change.

ARS researchers set out to find barley enzymes that could withstand the high heat levels created by malting. They assessed sugar beet, spinach and the model plant Arabidopsis for thermostability. Sugar beet proved to have the most impressive heat tolerance, so the investigators built a new barley enzyme with sugar beet as a model. They endowed their barley enzyme with a pivotal amino acid that gives sugar beet its thermal edge. By shuffling around the enzyme's other amino acids, the researchers have created three different heat-stable barley enzymes. All three have been patented.

The researchers are screening a core group of barley accessions held in the ARS National Small Grains Collection. They hope to find cultivars with natural variations that are identical to the mutations designed in the laboratory. They are using their patented enzymes as a search tool.

Researchers also are looking for variation in another barley enzyme, beta-amylase. They are looking for differences in the enzymatic activities of various malting and feed barleys. Once barleys containing all-natural, heat-friendly enzymes can be found in the ARS collection, they can then be crossed with other proven cultivars to develop what might be considered the ultimate malting barley.

Further information. Cynthia Henson, USDA-ARS Cereal Crops Research Unit, 1575 Linden Dr., Madison, WI, 53706; phone: [phone]; fax: [phone]; email: [e-mail].