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 o
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Effect of GPD1 and GPD2 Deletion on the Production of Glycerol and Ethanol in the Yeast Saccharomyces cerevisiae Jingjing Yu, Jian Dong, Cuiying Zhang, Junxia Li and Dongguang Xiao
Abstract 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.
Keywords GPD1 GPD2 romyces cerevisiae
Ethanol Glycerol VHG fermentation Saccha-
18.1 Introduction Ethanol, as the high-value renewable energy, plays an important role for the future [1, 2]. It is produced by anaerobic fermentation of glucose in yeast cells [3, 4]. Under normal anaerobic fermentation of Saccharomyces cerevisiae, in addition to the biomass, ethanol, and carbon dioxide, a number of other by-products such as glycerol, organic acids, and amino acids compounds are produced [3, 5]. In these J. Yu J. Dong C. Zhang J. Li D. Xiao (&) Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin Industrial Microbiology Key Laboratory, College of Biotechnology, Tianjin University of Science and Technology, Tianjin 300457, People’s Republic of China e-mail: [email protected]
T.-C. Zhang et al. (eds.), Proceedings of the 2012 International Conference on Applied Biotechnology (ICAB 2012), Lecture Notes in Electrical Engineering 249, DOI: 10.1007/978-3-642-37916-1_18, Ó Springer-Verlag Berlin Heidelberg 2014
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Fig. 18.1 Metabolic pathway of glycerol production in S. cerevisiae
by-products, glycerol is produced at up to 5 g/l, which is one of the main byproducts, accounting for up to 5 % of the carbon source in industrial fermentations [6]. If the target fermentation product is ethanol, then the formation of glycerol is a kind of waste. In S. cerevisiae cells, glycerol is synthesized from the reduction of dihydroxyacetone phosphate, which is a glycolytic intermediate in two sequential steps catalyzed by the rate-limiting NAD+-dependent glycerol-3-phosphate dehydrogenase (Fig. 18.1), and a secondary reaction catalyzed by glycerol-3-phosphatase. GPD1 and GPD2 encode two isoenzymes of glycerol-3-phosphate dehydrogenase [6–8]. The main role of glycerol is to balance the intracellular redox and adjust the osmotic stress within the cells [9, 10]. The purpose o
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