Document Detail

Elimination of glycerol production in anaerobic cultures of a Saccharomyces cerevisiae strain engineered to use acetic acid as an electron acceptor.
MedLine Citation:
PMID:  19915031     Owner:  NLM     Status:  MEDLINE    
In anaerobic cultures of wild-type Saccharomyces cerevisiae, glycerol production is essential to reoxidize NADH produced in biosynthetic processes. Consequently, glycerol is a major by-product during anaerobic production of ethanol by S. cerevisiae, the single largest fermentation process in industrial biotechnology. The present study investigates the possibility of completely eliminating glycerol production by engineering S. cerevisiae such that it can reoxidize NADH by the reduction of acetic acid to ethanol via NADH-dependent reactions. Acetic acid is available at significant amounts in lignocellulosic hydrolysates of agricultural residues. Consistent with earlier studies, deletion of the two genes encoding NAD-dependent glycerol-3-phosphate dehydrogenase (GPD1 and GPD2) led to elimination of glycerol production and an inability to grow anaerobically. However, when the E. coli mhpF gene, encoding the acetylating NAD-dependent acetaldehyde dehydrogenase (EC; acetaldehyde+NAD++coenzyme A<-->acetyl coenzyme A+NADH+H+), was expressed in the gpd1Delta gpd2Delta strain, anaerobic growth was restored by supplementation with 2.0 g liter(-1) acetic acid. The stoichiometry of acetate consumption and growth was consistent with the complete replacement of glycerol formation by acetate reduction to ethanol as the mechanism for NADH reoxidation. This study provides a proof of principle for the potential of this metabolic engineering strategy to improve ethanol yields, eliminate glycerol production, and partially convert acetate, which is a well-known inhibitor of yeast performance in lignocellulosic hydrolysates, to ethanol. Further research should address the kinetic aspects of acetate reduction and the effect of the elimination of glycerol production on cellular robustness (e.g., osmotolerance).
Víctor Guadalupe Medina; Marinka J H Almering; Antonius J A van Maris; Jack T Pronk
Publication Detail:
Type:  Journal Article     Date:  2009-11-13
Journal Detail:
Title:  Applied and environmental microbiology     Volume:  76     ISSN:  1098-5336     ISO Abbreviation:  Appl. Environ. Microbiol.     Publication Date:  2010 Jan 
Date Detail:
Created Date:  2009-12-23     Completed Date:  2010-02-26     Revised Date:  2010-09-27    
Medline Journal Info:
Nlm Unique ID:  7605801     Medline TA:  Appl Environ Microbiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  190-5     Citation Subset:  IM    
Kluyver Centre for Genomics of Industrial Fermentation, Julianalaan 67, 2628 BC Delft, the Netherlands.
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MeSH Terms
Acetic Acid / metabolism*
Escherichia coli / enzymology,  genetics
Escherichia coli Proteins / genetics
Ethanol / metabolism*
Gene Deletion
Gene Expression
Genetic Engineering*
Glycerol / metabolism*
Glycerolphosphate Dehydrogenase / genetics
Metabolic Networks and Pathways / genetics*
NAD / metabolism*
Recombination, Genetic
Saccharomyces cerevisiae / genetics,  metabolism*
Saccharomyces cerevisiae Proteins / genetics
Reg. No./Substance:
0/Escherichia coli Proteins; 0/Saccharomyces cerevisiae Proteins; 53-84-9/NAD; 56-81-5/Glycerol; 64-17-5/Ethanol; 64-19-7/Acetic Acid; EC 1.1.-/Glycerolphosphate Dehydrogenase

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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