ARS | Publication request: ETHANOL FERMENTATION OF SUGARS IN CORN STOVER DILUTE ACID HYDROLYSATES

Submitted to: Society of Industrial Microbiology Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: August 25, 2005
Publication Date: August 25, 2005
Citation: Nichols, N.N., Dien, B.S., Cotta, M.A. 2005. Ethanol fermentation of sugars in corn stover dilute acid hydrolysates [abstract]. Society of Industrial Microbiology. p. 85.

Technical Abstract: The biomass-to-ethanol fermentation process is limited in part by the presence of inhibitory compounds that are formed when biomass is pretreated with dilute acid to release fermentable sugars. We have developed a biological system for abatement of inhibitory chemicals and incorporated its use into an ethanol fermentation scheme. The system uses an Ascomycete fungus to remove furfural, 5 hydroxymethylfurfural, and other compounds that are inhibitory for fermenting microorganisms. Hydrolysate liquors prepared from corn stover were incubated with Coniochaeta ligniaria NRRL-30616. Bioabatement was followed by inoculation with recombinant Saccharomyces LNH ST, which has genes for xylose metabolism integrated on its chromosome, or Escherichia coli FBR5, a strain that was engineered to ferment mixed sugars selectively to ethanol. The yeast LNH-ST fermented sugars to ethanol in less than 20 hours, whereas the xylose in untreated dilute acid hydrolysates was consumed very slowly or not at all. E. coli FBR5 fermented glucose, xylose, and arabinose to ethanol in treated but not untreated hydrolysates. Therefore, bioabatement is a potential method for removing inhibitory compounds from biomass hydrolysate sugar streams.