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Comparative study on a series of recombinant flocculent Saccharomyces cerevisiae strains with different expression levels of xylose reductase and xylulokinase

Paper ID Volume ID Publish Year Pages File Format Full-Text
17457 42670 2011 6 PDF Available
Title
Comparative study on a series of recombinant flocculent Saccharomyces cerevisiae strains with different expression levels of xylose reductase and xylulokinase
Abstract

Ethanol production from xylose is important for the utilization of lignocellulosic biomass as raw materials. Recently, we reported the development of an industrial xylose-fermenting Saccharomyces cerevisiae strain, MA-R4, which was engineered by chromosomal integration to express the genes encoding xylose reductase and xylitol dehydrogenase from Pichia stipitis along with S. cerevisiae xylulokinase gene constitutively using the alcohol-fermenting flocculent yeast strain, IR-2. IR-2 has the highest xylulose-fermenting ability of the industrial diploid strains, making it a useful host strain for genetically engineering xylose-utilizing S. cerevisiae. To optimize the activities of xylose metabolizing enzymes in the metabolic engineering of IR-2 for further improvement of ethanol production from xylose, we constructed a set of recombinant isogenic strains harboring different combinations of genetic modifications present in MA-R4, and investigated the effect of constitutive expression of xylulokinase and of different levels of xylulokinase and xylose reductase activity on xylose fermentation. This strain comparison showed that constitutive expression of xylulokinase increased ethanol production from xylose at the expense of xylitol excretion, and that high activity of xylose reductase resulted in an increased rate of xylose consumption and an increased glycerol yield. Moreover, strain MA-R6, which has moderate xylulokinase activity, grew slightly better but accumulated more xylitol than strain MA-R4. These results suggest that fine-tuning of introduced enzyme activity in S. cerevisiae is important for improving xylose fermentation to ethanol.

Keywords
XR, xylose reductase; XDH, xylitol dehydrogenase; XK, xylulokinase; PsXR, XR from Pichia stipitis; PsXDH, XDH from Pichia stipitis; ScXK, XK from Saccharomyces cerevisiae; DCW, dry cell weightXylose fermentation; Ethanol production; Saccharomyces cerevisi
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Comparative study on a series of recombinant flocculent Saccharomyces cerevisiae strains with different expression levels of xylose reductase and xylulokinase
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Publisher
Database: Elsevier - ScienceDirect
Journal: Enzyme and Microbial Technology - Volume 48, Issues 6–7, 6 May 2011, Pages 466–471
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