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Fate of Bt Protein and Influence of Corn Hybrid on Ethanol Production

¹Fermentation Biotechnology Research Unit, National Center for Agricultural Utilization Research, Peoria, IL 61604. Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by the USDA implies no approval of the product to the exclusion of others that may also be suitable. ²Corresponding author. Phone: 309-681-6270. Fax: 309-681-6427. E-mail: dienb@ncaur.usda.gov. ³Department of Agricultural Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801.

Corn hybrids were compared to determine the fate of recombinant Bt protein (CRY1Ab from Bacillus thuringiensis) in coproducts 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 was examined for the presence of the Bt protein. Bt protein was found in the germ, gluten, and fiber fractions of Bt hybrids. In addition, one set of Bt and non-Bt hybrids were treated by the dry-grind ethanol process and Bt protein was monitored during each step of the process. The Bt protein was not detected after liquefaction. Subsequent experiments determined that the Bt protein is rapidly denatured at liquefaction temperatures. Finally, five hybrids were compared for ethanol yield after dry grinding. Analysis of fermentation data with an 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 on starch content. No difference, however, was observed between Bt and non-Bt corn hybrids for either ethanol productivity or yield.