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Regulatory aspects of bakers' yeast metabolism in aerobic fed‐batch cultures
Author(s) -
Woehrer W.,
Roehr M.
Publication year - 1981
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.260230308
Subject(s) - fermentation , yeast , respiratory quotient , ethanol , bioreactor , biochemistry , chemistry , ethanol fermentation , carbohydrate metabolism , metabolism , food science , glucose uptake , saccharomyces cerevisiae , biology , microbiology and biotechnology , organic chemistry , insulin
Abstract A highly instrumented computer‐coupled bioreactor is used to investigate metabolic changes of Saccharomyces cerevisiae in aerobic fed‐batch systems which are generally applied in bankers' yeast manufacture. The four types of metabolism (oxidation of glucose, aerobic fermentation, oxidation of glucose and ethanol, and oxidation of ethanol) appearing in such systems are characterized by four significant fermentation parameters: Respiratory quotient (RQ), glucose uptake rate ( Q g ), ethanol turnover rate ( Q EtOH ), and growth yield on glucose ( Y g ). Below the critical glucose concentration glucose and ethanol are utilized simultaneously. The shift from aerobic fermentation to nondiauxic growth on glucose and ethanol is not only dependent on glucose concentration. but also on the precultivation on cells. The uptake of ethanol is controlled by the glucose supply except in the case when ethanol is limiting; the oxygen uptake rate ( Q o2 ), however, is unaffected by the ratio of Q g and Q EtOH . Critical glucose concentration is not a constant value for a particular strain, but varies corresponding to the nutritional state of the cells.