Modulation of Glycerol and Ethanol Yields During Alcoholic Fermentation inSaccharomyces cerevisiae Strains Overexpressed or Disrupted forGPD1 Encoding Glycerol 3-Phosphate Dehydrogenase
✍ Scribed by Michnick, Sumio; Roustan, Jean-Louis; Remize, Fabienne; Barre, Pierre; Dequin, Sylvie
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 129 KB
- Volume
- 13
- Category
- Article
- ISSN
- 0749-503X
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✦ Synopsis
The possibility of the diversion of carbon flux from ethanol towards glycerol in Saccharomyces cerevisiae during alcoholic fermentation was investigated. Variations in the glycerol 3-phosphate dehydrogenase (GPDH) level and similar trends for alcohol dehydrogenase (ADH), pyruvate decarboxylase and glycerol-3-phosphatase were found when low and high glycerol-forming wine yeast strains were compared. GPDH is thus a limiting enzyme for glycerol production. Wine yeast strains with modulated GPD1 (encoding one of the two GPDH isoenzymes) expression were constructed and characterized during fermentation on glucose-rich medium. Engineered strains fermented glucose with a strongly modified [glycerol] : [ethanol] ratio. gpd1delta mutants exhibited a 50% decrease in glycerol production and increased ethanol yield. Overexpression of GPD1 on synthetic must (200 g/l glucose) resulted in a substantial increase in glycerol production ( x 4) at the expense of ethanol. Acetaldehyde accumulated through the competitive regeneration of NADH via GPDH. Accumulation of by-products such as pyruvate, acetate, acetoin, 2,3 butane-diol and succinate was observed, with a marked increase in acetoin production.