Effect of dissolved oxygen concentration on the intracellular flux distribution for pyruvate fermentation

The intracellular flux distributions in Torulopsis glabrata IFO 0005 over the typical time intervals for exponential growth phase and pyruvate production phase have been studied under various DO conditions, namely 1, 10, 40 and > 60% air saturation. The estimations of metabolic fluxes were made by combining material balances with the conversion rates of extracellular metabolites, where 19 metabolic reactions and 21 species were considered. The fluxes of key metabolic pathways were analyzed and compared in detail for the cultivation at different DO concentrations. The flux of NADH and energy generation and demands in all DO cases were also studied on the basis of metabolic fluxes calculated. Further investigation of total energy requirement for metabolism and intracellular redox balance will be valuable for in-depth understanding and improving this process. (C) 1999 Published by Elsevier Science B.V. All rights reserved.