Project description:The methylotrophic, thermotolerant yeast Ogataea parapolymorpha (formerly Hansenula polymorpha) is an industrially relevant production host and exhibits a respiratory metabolism in the presence of oxygen. It possesses a branched respiratory chain with multiple entry points for NADH-derived electrons that differ in complexity and degree of energy conservation: proton-translocating respiratory Complex I and three putative alternative NADH dehydrogenases. To investigate the physiological importance of Complex I, wild type O. parapolymorpha and a Complex I-disrupted mutant were cultured in glucose-grown bioreactor experiments in batch, chemostat and retentostat cultivations which allowed quantitative characterization of the strains over a wide range of growth rates in the presence and absence of excess substrate.