1 Quantitative Analysis of Metabolic Fluxes in Anaerobic Chemostat Cultivations of Yeast Strains By Yanyu Fang

In this work the anaerobic physiology in chemostat cultures at different dilution rates was studied for three different yeast strains: CBS 8066, TMB 3000 and a strain overexpressing the gene encoding glycerol-3-P dehydrogenase (GPD2). The highest ethanol yield, 0.525 C-mole / C-mole glucose, was obtained by TMB 3000 at the dilution rate of 0.08 h-1, but the ethanol yield of TMB 3000 decreased when dilution rates increased. The highest glycerol yield was as expect obtained with the GPD2-mutant, giving yield of 0.111 (C-mole / C-mole glucose) at dilution rate of 0.08 h-1. The measurements results were put into a stoichiometric network model for the purpose of making a metabolic flux analysis (MFA) of the strains. The results from this analysis showed that the GPD2-mutant had the most active EMP pathway compared to TMB 3000 and CBS 8066, but the least active biosynthetic pathway. CBS 8066 had the most active the TCA pathway compared to the other two strains. 1