engleski

Mathematical model of yeasts metabolism under oxygen saturation conditions

This paper deals with aerobic growth of yeasts and it proposes the model of yeasts metabolism under oxygen saturation conditions. Data concerning batch growth of four yeasts (Saccharomyces cerevisiae, Saccharomyces uvarum, Shizosaccharomyces pombe and Candida utilis) grown on four different carbon sources (glucose, sucrose, galactose and maltose) were taken from the literature. Yeasts were grown under conditions of large oxygen transfer coefficient and low biomass concentration. During batch growth, concentrations of the following substances were experimentally measured: biomass, substrate, ethanol, oxygen and carbon dioxide. A computer model of yeasts metabolism under chemostat conditions based on data from batch fermentations is outlined. The key variables of the model are concentrations of biomass, substrate, ethanol, respiratory intermediates, oxygen, carbon dioxide and ATP. Initial values of intracellular concentrations of the respiratory intermediates (pyruvate) as well as ATP were not measured experimentally but were estimated from the intracellular balances of the initial state and the measured parameters. The computer model is used to reproduce experimental data obtained under fed-batch growth. With aim to test the model assumptions responses of metabolism to impulses of introduced sugars under chemostat conditions are investigated. The purpose of the acquired predictions is to test the hypothesis of saturated respiratory capacity in yeasts.

yeasts; metabolism; respiration; chemostat; structured model

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