Executive Summary

Corn fiber was hydrolysed using dilute sulfuric acid (0.1-0.5%, v/v) at 121°C, enzymes (cellulase supplemented with cellobiase) or a combination of both (acid and enzyme). Sulfuric acid (0.3-0.5%, v/v) resulted in releasing 29.2-29.9 g/L total sugars from 63 g/L corn fiber. Further treatment with enzymes increased the total sugar level from 29.9 g/L to approximately 40 g/L. Use of enzymes alone resulted in a sugar concentration of 24.3 g/L. Fermentation of corn fiber hydrolysate suggested that dilute sulfuric acid treatment released components that inhibited cell growth and fermentation of C. beijerinckii BA101. It may be possible that salt formed during corn fiber hydrolysate neutralization inhibited cell growth. Enzyme hydrolysed corn fiber (without acid treatment) did not show any signs of cell inhibition and resulted in the production of 8.1 g/L total acetone, butanol, and ethanol (ABE) from 23.9 g/L total sugars. The ABE concentration in enzyme hydrolysed corn fiber hydrolysate was low due to initial low sugar concentration. It is suggested that inhibitory components be removed from the dilute sulfuric acid corn fiber hydrolysate prior to fermentation. Another possibility could be that a new culture capable of fermenting such a hydrolysate be developed. We also studied effect of inhibitors on butanol fermentation.

Project Highlights

1. Enzymatically hydrolyzed corn fiber was fermented to butanol successfully.
2. Acid hydrolyzed corn fiber was found to be inhibitory to growth and fermentation.
3. Attempts were made (partly successful) to identify inhibitors and observe their affects on butanol fermentation.
4. This project is leading us into a new direction on production of butanol from corn fiber hydrolysate and distillers dry grains solubles (DDGS). This impact is viewed as one of the main highlights of the project.

PI (Nasib Qureshi) changed his employer (in 2003) the University of Illinois at Urbana Champaign, IL. Currently Nasib Qureshi is working for the United States Department of Agriculture, National Center for Agricultural Utilization Research, Peoria, IL. In spite of this change our research efforts on this project continued uninterrupted.

Professor Hans P. Blaschek provided me with an admirable support and help in carrying out objectives of this project in particular on my separation from the University of Illinois. Without his help, it would have been difficult to meet our project objectives.

Itemized Equipment Over $5,000

None

List of Publications, Abstracts

1. The results of our investigation were presented at the 25th Biotechnology Symposium for Fuels and Chemicals, Breckenridge, CO, May 4-7, 2003

   "Qureshi N, Ebener J, Dien B, Cotta MA, Blaschek HP (2002) Corn fiber hydrolysis and fermentation to butanol using Clostridium beijerinckii BA101"

2. A research paper on the production of butanol from corn fiber is under preparation. It is expected that the paper will be submitted by Dec. 31, 2004 to an International Journal for publication.

Involvement of Collaborators

IMBA project played a major role in collaborative research with the USDA laboratory in Peoria, IL. It is anticipated that our research on butanol fermentation would lead into a new direction and it is expected that the new process would economize butanol fermentation.

Publications

As soon as this work has been published, a copy of our publication would be mailed for your records.