Physiological and metabolic flux screening of Saccharomyces cerevisiae single knockout mutants on different carbon sources: Dissertation

A novel method for high-throughput stoichiometric and metabolic flux profiling was developed and a set of deletion mutants of S. cerevisiae, which are known to be involved in central carbon metabolism were selected and investigated on glucose, galactose and fructose. On glucose and fructose, the growth was predominantly fermentative and on galactose, respiration was more active. mae1D strain did not show any significant growth phenotype on glucose, however, it had highest PPP flux on galactose, which could be due to redirection of NADPH production to the PPP. On fructose, mae1D strain had highest oxygen uptake rate with very low ethanol yield, which could be due to reduced PPP flux and to maintain NADPH levels either via NADPH specific -isocitrate dehydrogenase or -aldehyde dehydro-genase. imp2'D strain had lowest PPP flux and very high respiratory activity on galactose; and pck1D strain had lowest PPP flux on glucose, which might also point to a possible activation of malic enzyme. On fructose, hxt17D strain had highest sugar consumption and ethanol production rates and imp2'D strain had highest ethanol yield. The functional prediction of hypothetical genes by utilising this quantitative data using computational analyses suggested a possible role in glycolysis or pyruvate metabolism for YBR184W and low affinity transporter role for YIL170W.