Premium
Physiological, biochemical, and mathematical studies of micro‐aerobic continuous ethanol fermentation by Saccharomyces cerevisiae . III: Mathematical model of cellular energetics and catabolism
Author(s) -
Grosz Ron,
Stephanopoulos Gregory
Publication year - 1990
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.260361008
Subject(s) - chemostat , catabolism , context (archaeology) , intracellular , biochemistry , fermentation , saccharomyces cerevisiae , chemistry , yeast , metabolic pathway , biology , metabolism , biophysics , bacteria , paleontology , genetics
Mathematical models of the catabolic pathways, the utilization and waste of ATP, and the factors affecting yeast growth in a micro‐aerobic chemostat are presented. The models incorporate the intracellular metabolite and enzyme activity assays performed in Part II to explain the unusual macroscopic chemostat behaviors reported in Part I. The catabolic model successfully predicts a maximum in the specific ethanol productivity as a function of the intracellular ATP concentration. The ATP balance model enables the prediction of the intracellular ATP concentration and the ATP yield for given dissolved oxygen concentrations. Finally, in the context of a growth model, singularity theory provides a framework to explain the transition observed in Part I between hysteresis and the monotonic biomass versus oxygenation profiles in response to changes in the nutrient composition. The models serve to organize data and to concretely express proposed metabolic mechanisms and cause–effect hypotheses. The model is only applicable to the micro‐aerobic and excess glucose conditions encountered in this study.