Conversion of corn fiber to ethanol by recombinant E. coli strain FBR3

  • B S Dien
  • L B Iten
  • R J Bothast

DOI: 10.1038/sj.jim.2900628

Cite this article as:
Dien, B., Iten, L. & Bothast, R. J Ind Microbiol Biotech (1999) 22: 575. doi:10.1038/sj.jim.2900628

Escherichia coli

strain FBR3 that is an efficient biocatalyst for converting mixed sugar streams (eg, arabinose, glucose, and xylose) into ethanol. In this report, the strain was tested for conversion of corn fiber hydrolysates into ethanol. Corn fiber hydrolysates with total sugar concentrations of 7.5% (w/v) were prepared by reacting corn fiber with dilute sulfuric acid at 145°C. Initial fermentations of the hydrolysate by strain FBR3 had lag times of approximately 30 h judged by ethanol production. Further experiments indicated that the acetate present in the hydrolysate could not solely account for the long lag. The lag phase was greatly reduced by growing the pre-seed and seed cultures on corn fiber hydrolysate. Ethanol yields for the optimized fermentations were 90% of theoretical. Maximum ethanol concentrations were 2.80% w/v, and the fermentations were completed in approximately 50 h. The optimal pH for the fermentation was 6.5. Below this pH, sugar consumption was incomplete and above it, excess base addition was required throughout the fermentation. Two alternative neutralization methods (overliming and overliming with sulfite addition) have been reported for improving the fermentability of lignocellulosic hydrolysates. These methods further reduced the lag phase of the fermentation, albeit by a minor amount.

Keywords: alcohol; biofuel; pentoses; corn fiber; ethanologenic; Escherichia coli 

Copyright information

© Society for Industrial Microbiology 1999

Authors and Affiliations

  • B S Dien
    • 1
  • L B Iten
    • 1
  • R J Bothast
    • 1
  1. 1.Fermentation Biochemistry Research Unit, National Center for Agricultural Utilization Research, USDA, Agricultural Research Service, 1815 North University Street, Peoria, Illinois 61604, USAUS

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