Effect of GPD1 and GPD2 Deletion on the Production of Glycerol and Ethanol in the Yeast Saccharomyces cerevisiae

Glycerol is the main by-product in ethanol production during the very high gravity (VHG) fermentation process by Saccharomyces cerevisiae. This study investigates the effect of GPD1 or GPD2 (encoding 3-phosphate dehydrogenase) deletion on the production of glycerol and ethanol through the VHG fermentation. We observed that deletion of GPD1 resulted in 45.30 % reduction in glycerol production compared with the parent strain, and ethanol production reached the levels of 15.8 +/- 0.03 (v/v), while we failed to observe such a significant decrease in glycerol production for the GPD2 deletion mutants whose ethanol production was 15.7 +/- 0.03 (v/v). It can be concluded that deletion of either GPD1 or GPD2 can elevate ethanol production, and that GPD1 deletion can significantly reduce glycerol production, suggesting that GPD1 plays a dominant role in regulating glycerol synthesis during the process of VHG fermentation.