Boosting Ethanol Production Efficiency with Enzymes

As ethanol production increases, so does the demand for suitable feedstocks.

Affordable, plentiful and easy to work with, corn is currently the feedstock of choice in the United States. So Agricultural Research Service (ARS) scientists at the Eastern Regional Research Center (ERRC) in Wyndmoor, Pa., are investigating ways to avoid overburdening the corn market as ethanol production expands.

Annual U.S. ethanol production is projected to increase from 5 billion gallons in 2006 to as many as 13 billion gallons in 2009. So what options will ethanol producers have? One solution is to increase conversion efficiency.

David Johnston, a food technologist in the ERRC's Crop Conversion Science and Engineering Research Unit, is investigating new processes using protease enzymes from microbial and fungal sources to make ethanol more efficiently. He has found that the enzymes make more nutrients available for the yeast, expediting fermentation of sugars. Protease enzymes can also facilitate the process of dewatering the solids that remain after the ethanol has been extracted.

Working with Vijay Singh, an agricultural engineer at the University of Illinois, Johnston conducted a field trial at a small wet-milling facility in Panang, Malaysia. They soaked U.S. corn in water for several hours and then applied the enzymes (provided by biotechnology company Genencor International Inc., of Palo Alto, Calif.). The scientists found that adding enzymes during processing increased starch recovery, just as it had in laboratory trials.

The starches can be used in more than 1,000 different products, from paper and sheet rock to high fructose corn syrup and ethanol. Economic analysis will be the next step, and Johnston and Singh are planning to replicate the trial at several more commercial facilities.

This is one of many ERRC research projects related to improving understanding and production of biofuels. Read more about the research in the April 2007 issue of Agricultural Research magazine.

ARS is the U.S. Department of Agriculture's chief in-house scientific research agency.

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