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Minimization of glycerol synthesis in industrial ethanol yeast without influencing its fermentation performance

Paper ID Volume ID Publish Year Pages File Format Full-Text
31834 44842 2011 11 PDF Available
Title
Minimization of glycerol synthesis in industrial ethanol yeast without influencing its fermentation performance
Abstract

To synthesize glycerol, a major by-product during anaerobic production of ethanol, the yeast Saccharomyces cerevisiae would consume up to 4% of the sugar feedstock in typical industrial ethanol processes. The present study was dedicated to decreasing the glycerol production mostly in industrial ethanol producing yeast without affecting its desirable fermentation properties including high osmotic and ethanol tolerance, natural robustness in industrial processes. In the present study, the GPD1 gene, encoding NAD+-dependent glycerol-3-phosphate dehydrogenase in an industrial ethanol producing strain of S. cerevisiae, was deleted. Simultaneously, a non-phosphorylating NADP+-dependent glyceraldehyde-3-phosphate dehydrogenase (GAPN) from Bacillus cereus was expressed in the mutant deletion of GPD1. Although the resultant strain AG1A (gpd1△ PPGK-gapN) exhibited a 48.7±0.3% (relative to the amount of substrate consumed) lower glycerol yield and a 7.6±0.1% (relative to the amount of substrate consumed) higher ethanol yield compared to the wild-type strain, it was sensitive to osmotic stress and failed to ferment on 25% glucose. However, when trehalose synthesis genes TPS1 and TPS2 were over-expressed in the above recombinant strain AG1A, its high osmotic stress tolerance was not only restored but also improved. In addition, this new recombinant yeast strain displayed further reduced glycerol yield, indistinguishable maximum specific growth rate (μmax) and fermentation ability compared to the wild type in anaerobic batch fermentations. This study provides a promising strategy to improve ethanol yields by minimization of glycerol production.

Keywords
Saccharomyces cerevisiae; Glycerol-3-phosphate dehydrogenase; NADP+-dependent glyceraldehyde-3-phosphate dehydrogenase; Glycerol production; Ethanol yield; Osmotic stress tolerance
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Publisher
Database: Elsevier - ScienceDirect
Journal: Metabolic Engineering - Volume 13, Issue 1, January 2011, Pages 49–59
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