Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 8/1/2005
Publication Date: 8/8/2005
Citation: Hicks, K.B., Senske, G.E., Hotchkiss, A.T., O'Brien, D. 2005. Screening of commercial beta-glucanases for complete hydrolysis of barley beta-blucan to glucose. Meeting Abstract 230th ACS National Meeting, Washington DC, August 28-September 1, CARB Division Paper #18.
Technical Abstract: Over 3.4 billion gallons of fuel ethanol were produced in the U.S. in 2004. The primary feedstock for this process was corn and almost 10% of the U.S. crop went for this single purpose. To prevent depletion of the U.S. corn supply, we are examining production of ethanol from barley, a complementary crop that grows in non-corn belt states where ethanol demand is high. Barley is inferior to corn for ethanol production because of lower starch content (less ethanol yield) and because of the presence of mixed linkage beta-glucans that cause high viscosity and technical problems during processing. Complete hydrolysis of barley beta-glucans to glucose would solve the viscosity problems and increase ethanol yield, due to the fermentable glucose formed. In this study eight commercial or pre-commercial enzyme preparations exhibiting beta-glucanase activity were screened for their ability to release glucose from soluble barley beta-glucan. Enzyme activities were determined in a model system at pH 5.0 in acetate buffer containing a purified barley beta-glucan at temperatures of 45-80 degrees C depending on the enzyme. While all enzyme preparations hydrolyzed beta-glucan to some degree, their glucose-releasing activities varied considerably. For one enzyme preparation, 40 % of the beta-glucan was hydrolyzed to glucose in 1 hr and 83% in 26 hr at 55 degrees C. Strategies to increase hydrolysis to 100% are proposed.