Metabolic Control Analysis of Glycerol Synthesis in Saccharomyces cerevisiae

Metabolic Control Analysis of Glycerol Synthesis in Saccharomyces cerevisiae

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Model Structure

Glycerol is a major by-product of ethanol fermentation by Saccharomyces cerevisiae, and it is a valuable product in the wine, beer and ethanol production industries. For this reason, several attempts have been made to manufacture an industrial strain of S. cerevisiae that is capable of producing larger than normal amounts of glycerol. These attempts have generally employed one of three potential strategies:

  • altered growth conditions;

  • use of improved wine-producing S. cerevisiae strains by classical selective breeding techniques; and

  • use of improved strains by genetic modification and molecular manipulation.

These strategies have proven to be successful, to a degree. More glycerol is synthesised, but in addition, there are increased quantities of other by-products such as acetaldehyde and acetate. For the wine making industry in particular, these products are undesirable.

In order to gain a better understanding of the glycerol synthesis pathway, Cronwright et al. (2002) have devloped a detailed kinetic model of the reactions involved (see the figure below). The model provides insight into the roles of, and the extents to which, the redox balance, substrate availability, modifier concentrations, and intrinsic enzyme capabilities control the amount of glycerol produced. Model simulation results may also provide some insight into the inherent capacities of the pathway and therefore facilitate a more knowledgable approach to controlled glycerol syntheisi by S. cerevisiae.

The complete original paper reference is cited below:

Metabolic Control Analysis of Glycerol Synthesis in Saccharomyces cerevisiae , Garth R. Cronwright, Johann M. Rohwer, and Bernard A. Prior, 2002, Applied and Environmental Microbiology , 68, 4448-4456. PubMed ID: 12200299

Schematic diagram of the glycerol synthesis pathway in Saccharomyces cerevisiae.