Reduction of glycerol production to improve ethanol yield in an engineered Saccharomyces cerevisiae using glycerol as a substrate

Abstract

Ethanol plays an important role in substituting the increasingly limited oil as the high-value renewable fuel In our previous studies we successfully established the conversion of glycerol to ethanol by overexpression of pGcyaDak with pGup1Cas in Saccharomyces cerevisiae In addition to increasing ethanol production using glycerol as substrate we minimized the synthesis of glycerol which is the main byproduct in ethanol fermentation processing The glycerol production pathway was impaired by deletion of the genes FPS1 and GPD2 Strains deleted for both FPS1 and GPD2 reduce glycerol production and become highly sensitive to osmotic stress We provide osmotic protection in YPH499fps1 Delta gpd2 Delta by overexpression of Gap1 In this study S cerevisiae using glycerol as substrate was modified through one-step gene disruption for redirection of glycerol carbon flux Into ethanol by the deletion of two glycerol production genes FPS1 and GPD2 The overall ethanol production in the modified strain YPH499fps1 Delta gpd2 Delta (pGcyaDak pGupCas) was about 4 4 g l(-1) These results demonstrate the possibility of providing protection against osmotic stress while simultaneously increasing ethanol and reducing glycerol production in S cerevisiae strains using glycerol as a carbon source (C) 2010 Elsevier B V All rights reserved