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Optimization of spent sulfite liquor fermentation

Paper ID Volume ID Publish Year Pages File Format Full-Text
17938 42706 2008 6 PDF Available
Title
Optimization of spent sulfite liquor fermentation
Abstract

The hemicellulose-derived sugars in spent sulfite liquor (SSL), a process stream of the sulfite pulping process, may be fermented to ethanol. Low nutrient concentration, the presence of inhibitors, and a large proportion of xylose limit fermentation of the sugars in SSL. Factorial design experiments were used to find optimum conditions for hexose and xylose fermentation using a robust SSL-adapted (non-xylose fermenting) yeast strain, and Saccharomyces cerevisiae 259ST, a genetically modified strain capable of fermenting xylose.Xylose fermentation was slower than hexose fermentation, and required the detoxification of SSL and/or the addition of hexose sugars to support a large yeast concentration. Xylose fermentation and the growth of the genetically modified yeast in SSL were closely correlated. Under fermentation conditions where no growth was observed (yeast concentration ∼2 g/L and pH < 5), no xylose was fermented in SSL. Under conditions favorable for growth (yeast concentration ∼6 g/L and pH > 5.3), an average of 5.5 g/L ethanol was obtained from xylose fermentation. SSL pretreatment and the addition of nutrients were also beneficial. For the SSL-adapted strain, ethanol yield was improved by increasing the yeast concentration, however while adding nutrients and raising the pH increased yeast growth, these changes resulted in a decrease in the ethanol yield from greater than 85% of theoretical to 70%.

Keywords
Xylose; Fermentation; Saccharomyces cerevisiae; Spent sulfite liquor
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Optimization of spent sulfite liquor fermentation
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Publisher
Database: Elsevier - ScienceDirect
Journal: Enzyme and Microbial Technology - Volume 42, Issue 3, 4 February 2008, Pages 259–264
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us