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  • Fermentation of reactive-membrane-extracted and ammonium-hydroxide-conditioned dilute-acid-pretreated corn stover.

Fermentation of reactive-membrane-extracted and ammonium-hydroxide-conditioned dilute-acid-pretreated corn stover.

Applied biochemistry and biotechnology (2011-12-14)
David L Grzenia, S Ranil Wickramasinghe, Daniel J Schell
ABSTRACT

Acid-pretreated biomass contains various compounds (acetic acid, etc.) that are inhibitory to fermentative microorganisms. Removing or deactivating these compounds using detoxification methods such as overliming or ammonium hydroxide conditioning (AHC) improves sugar-to-ethanol yields. In this study, we treated the liquor fraction of dilute-acid-pretreated corn stover using AHC and a new reactive membrane extraction technique, both separately and in combination, and then the sugars in the treated liquors were fermented to ethanol with the glucose-xylose-fermenting bacterium, Zymomonas mobilis 8b. We performed reactive extraction with mixtures of octanol/Alamine 336 or oleyl alcohol/Alamine 336. The best ethanol yields and rates were achieved for oleyl alcohol-extracted hydrolysates followed by AHC hydrolysates, while octanol-extracted hydrolysates were unfermentable because highly toxic octanol was found in the hydrolysate. Adding olive oil significantly improved yields for octanol-extracted hydrolysate. Additional work is underway to determine if this technology is a cost-effective alternative to traditional hydrolysate conditioning processes.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Oleyl alcohol, technical grade, 85%
Sigma-Aldrich
Oleyl alcohol, ≥99% (GC)
Sigma-Aldrich
Ammonium hydroxide solution, BioUltra, ~1 M NH3 in H2O (T)
Sigma-Aldrich
Ammonium hydroxide solution, puriss., 30-33% NH3 in H2O
Sigma-Aldrich
Ammonium hydroxide solution, ACS reagent, 28.0-30.0% NH3 basis
Sigma-Aldrich
Ammonium hydroxide solution, puriss. p.a., reag. ISO, reag. Ph. Eur., ~25% NH3 basis
Sigma-Aldrich
Ammonium hydroxide solution, puriss., meets analytical specification of Ph. Eur., 25-30% NH3 basis
Sigma-Aldrich
Ammonium hydroxide solution, puriss. p.a. plus, ≥25% NH3 in H2O
Sigma-Aldrich
Ammonium hydroxide solution, 28% NH3 in H2O, ≥99.99% trace metals basis