Investigation of the contribution of Complex I to respiratory energy-coupling in glucose-grown cultures of the Crabtree-negative yeast Ogataea parapolymorpha

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. RNASeq-based transcriptome analysis was performed in biological duplicates on samples taken from aerobic, glucose-grown bioreactor cultivation. Conditions were batch cultivation (0.37h-1), chemostat cultivation at dilution rates of 0.1 and 0.025 h-1, as well as late-stage retentostat cultivation (approx. 0.001 h-1) for both wild type O. parapolymorpha (CBS11895) and a mutant devoid of functional repiratory Complex I (IMD010).