Document Detail

Key process conditions for production of C(4) dicarboxylic acids in bioreactor batch cultures of an engineered Saccharomyces cerevisiae strain.
MedLine Citation:
PMID:  20008165     Owner:  NLM     Status:  MEDLINE    
A recent effort to improve malic acid production by Saccharomyces cerevisiae by means of metabolic engineering resulted in a strain that produced up to 59 g liter(-1) of malate at a yield of 0.42 mol (mol glucose)(-1) in calcium carbonate-buffered shake flask cultures. With shake flasks, process parameters that are important for scaling up this process cannot be controlled independently. In this study, growth and product formation by the engineered strain were studied in bioreactors in order to separately analyze the effects of pH, calcium, and carbon dioxide and oxygen availability. A near-neutral pH, which in shake flasks was achieved by adding CaCO(3), was required for efficient C(4) dicarboxylic acid production. Increased calcium concentrations, a side effect of CaCO(3) dissolution, had a small positive effect on malate formation. Carbon dioxide enrichment of the sparging gas (up to 15% [vol/vol]) improved production of both malate and succinate. At higher concentrations, succinate titers further increased, reaching 0.29 mol (mol glucose)(-1), whereas malate formation strongly decreased. Although fully aerobic conditions could be achieved, it was found that moderate oxygen limitation benefitted malate production. In conclusion, malic acid production with the engineered S. cerevisiae strain could be successfully transferred from shake flasks to 1-liter batch bioreactors by simultaneous optimization of four process parameters (pH and concentrations of CO(2), calcium, and O(2)). Under optimized conditions, a malate yield of 0.48 +/- 0.01 mol (mol glucose)(-1) was obtained in bioreactors, a 19% increase over yields in shake flask experiments.
Rintze M Zelle; Erik de Hulster; Wendy Kloezen; Jack T Pronk; Antonius J A van Maris
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2009-12-11
Journal Detail:
Title:  Applied and environmental microbiology     Volume:  76     ISSN:  1098-5336     ISO Abbreviation:  Appl. Environ. Microbiol.     Publication Date:  2010 Feb 
Date Detail:
Created Date:  2010-01-28     Completed Date:  2010-04-16     Revised Date:  2013-05-31    
Medline Journal Info:
Nlm Unique ID:  7605801     Medline TA:  Appl Environ Microbiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  744-50     Citation Subset:  IM    
Department of Biotechnology, Delft University of Technology and Kluyver Centre for Genomics of Industrial Fermentation, BC Delft, The Netherlands.
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MeSH Terms
Aerobiosis / genetics
Anaerobiosis / genetics
Carbon Dioxide / metabolism
Cell Culture Techniques / methods
Culture Media / metabolism
Directed Molecular Evolution
Fermentation / genetics
Genetic Engineering
Genetic Enhancement
Glucose / genetics,  metabolism
Hydrogen-Ion Concentration
Industrial Microbiology / methods*
Malates / metabolism*
Oxygen / metabolism
Saccharomyces cerevisiae / genetics,  growth & development,  metabolism*
Succinic Acid / metabolism*
Waste Disposal, Fluid
Reg. No./Substance:
0/Culture Media; 0/Malates; 110-15-6/Succinic Acid; 124-38-9/Carbon Dioxide; 50-99-7/Glucose; 6915-15-7/malic acid; 7782-44-7/Oxygen

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