ARS | Publication request: CONVERSION OF CORN FIBER TO ETHANOL USING RECOMBINANT ESCHERICHIA COLI STRAINS

Submitted to: Biotechnology for Fuels and Chemicals Symposium Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: May 6, 1999
Publication Date: N/A

Technical Abstract: In 1997, about one billion gallons of ethanol were produced in the United States, of which 95% was derived from fermentation of corn starch. We are investigating corn fiber as a novel fermentation feedstock. Corn fiber, a low value co-product generated during wet milling, is desirable as a feedstock because it is centrally stockpiled, low in naturally occurring inhibitors, and contains over 50% w/w carbohydrates. We are developing a process for conversion of corn fiber into ethanol. In the first step, the non-cellulosic carbohydrates are hydrolyzed into monomers by treating with dilute sulfuric acid at 150 deg C. The residual fibers are removed with a basket centrifuge and the supernatant neutralized with calcium hydroxide. The resulting hydrolysate contains a mixture of sugars including arabinose, glucose, and xylose. The hydrolysate is converted into ethanol using recombinant Escherichia coli; either strains K011 or FBR3, a novel strain developed in this laboratory. Ethanol yields that are approximately 90% o theoretical have been achieved using both strains. Current research is focused on optimizing conditions for producing the seed cultures, neutralizing the hydrolysate, and developing an industrial-type medium.