Submitted to: Cereal Chemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/17/2002
Publication Date: 7/1/2002
Citation: DIEN, B.S., BOTHAST, R.J., ITEN, L.B., BARRIOS, L., ECKHOFF, S.R. FATE OF BT PROTEIN AND INFLUENCE OF CORN HYBRID ON ETHANOL PRODUCTION. CEREAL CHEMISTRY. 2002. V. 79. P. 582-585. Interpretive Summary: Last year over 1.8 billion gallons of fuel ethanol were produced from nearly 700 million bushels of corn. Ethanol demand is expected to more than double in the next few years with the phase out of MTBE (methyl tertiary butyl ether) as a fuel oxygenate. In order to improve the yield of ethanol from a bushel of corn, production of grains with tailored traits, e.g., corn with higher starch content and enhanced fermentability, are desirable attributes. In this research with traditional alcohol fermentations, we found that the digestibility of starch influenced alcohol yield more than total starch content and that the insecticidal Bt protein in genetically modified corn was not detectable after fermentation.
Technical Abstract: Corn hybrids were compared to determine the fate of recombinant Bt protein (CRY1Ab from Bacillus thuringiensis) in co-products from dry grind and wet milled corn during production of fuel ethanol. Two pairs of Bt and non-Bt hybrids were wet-milled and each fraction examined for the presence of the Bt protein. Bt protein was found in the germ, gluten, and fiber fractions. .In addition, one set of Bt and non-Bt hybrids were dry grind and Bt protei monitored during each step of the process. The Bt protein was not detected following liquefaction. Subsequent experiments determined that the Bt protein is rapidly denatured at liquefaction temperatures. Finally, five hybrids were compared for ethanol yield following dry grinding. Analysis of fermentation data with a F-test revealed the percent of total starch available for conversion into ethanol varied significantly among the hybrids (p < 0.002), indicating ethanol yield is not exclusively dependent upon starch content. No difference, however, was observed between Bt and non-Bt corn hybrids for either ethanol productivity or yield.