Submitted to: Biotechnology for Fuels and Chemicals Symposium Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: May 7, 2003
Publication Date: May 7, 2003
Citation: DIEN, B.S., NICHOLS, N.N., LI, X., COTTA, M.A., BOTHAST, R.J. CONVERSION OF CORN FIBROUS MATERIAL INTO ETHANOL. 25TH SYMPOSIUM ON BIOTECHNOLOGY FOR FUELS AND CHEMICALS. 2003. ABSTRACT P. 68. Technical Abstract: Over 1.7 billion gallons of fuel ethanol were produced in the U.S. (2001), over 90% of which was produced from corn. Corn is prepared for ethanol fermentation by either wet milling or dry grinding in approximately equal volumes. In both processes, the fibrous components of the kernel are folded into animal feed co-products. U.S. ethanol production is expected to continue to increase, which may saturate these feed markets. We have investigated the possibility of converting the fibers to ethanol as an alternative use for the byproduct. Corn fiber (wet milling) and distillers wet grains (dry grind) were both analyzed for carbohydrate composition and determined to each have a high fraction of fermentable carbohydrates. Each fiber product was converted to ethanol by pretreating with dilute sulfuric acid and fermenting the sugars using either a recombinant ethanologenic Escherichia coli (FBR5) or Saccharomyces cerevisiae. For the S. cerevisiae fermentations, cellulase was also added to hydrolyze the cellulose. Strain FBR5 has the potential for higher ethanol yields than S. cerevisiae because it ferments both pentoses and hexoses. FBR5 fermentations were completed typically in 30-48 h and gave ethanol yields 90-96% of theoretical, based upon fermentable sugars. Yeast fermentations gave yields 92% of theoretical, based upon glucan content.