Physiological and genetic engineering of cytosolic redox metabolism in Saccharomyces cerevisiae for improved glycerol production |
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Authors: | Geertman Jan-Maarten A van Maris Antonius J A van Dijken Johannes P Pronk Jack T |
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Affiliation: | Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands. |
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Abstract: | Previous metabolic engineering strategies for improving glycerol production by Saccharomyces cerevisiae were constrained to a maximum theoretical glycerol yield of 1 mol.(molglucose)(-1) due to the introduction of rigid carbon, ATP or redox stoichiometries. In the present study, we sought to circumvent these constraints by (i) maintaining flexibility at fructose-1,6-bisphosphatase and triosephosphate isomerase, while (ii) eliminating reactions that compete with glycerol formation for cytosolic NADH and (iii) enabling oxidative catabolism within the mitochondrial matrix. In aerobic, glucose-grown batch cultures a S. cerevisiae strain, in which the pyruvate decarboxylases the external NADH dehydrogenases and the respiratory chain-linked glycerol-3-phosphate dehydrogenase were deleted for this purpose, produced glycerol at a yield of 0.90 mol.(molglucose)(-1). In aerobic glucose-limited chemostat cultures, the glycerol yield was ca. 25% lower, suggesting the involvement of an alternative glucose-sensitive mechanism for oxidation of cytosolic NADH. Nevertheless, in vivo generation of additional cytosolic NADH by co-feeding of formate to aerobic, glucose-limited chemostat cultures increased the glycerol yield on glucose to 1.08 mol mol(-1). To our knowledge, this is the highest glycerol yield reported for S. cerevisiae. |
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Keywords: | Saccharomyces cerevisiae Glycerol Cofactor Cytosolic redox metabolism Metabolic engineering NADH dehydrogenase |
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