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Effects of Glucose Fluctuations on Synchrony in Fed‐Batch Fermentation of Saccharomyces cerevisiae
Author(s) -
Namdev Pradyumna K.,
Thompson B. G.,
Ward Dennis B.,
Gray Murray R.
Publication year - 1992
Publication title -
biotechnology progress
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.572
H-Index - 129
eISSN - 1520-6033
pISSN - 8756-7938
DOI - 10.1021/bp00018a005
Subject(s) - chemostat , dilution , fermentation , saccharomyces cerevisiae , mixing (physics) , population , biology , bioreactor , fraction (chemistry) , yeast , chemistry , food science , biochemistry , chromatography , physics , bacteria , thermodynamics , botany , genetics , demography , quantum mechanics , sociology
The effects of transient conditions, due to fed‐batch dynamics and fluctuations in glucose supply, on synchronous growth were evaluated by conducting fed‐batch fermentation of Saccharomyces cerevisiae. Chemostat operation with dilution rates of 0.2 and 0.1 h −1 produced periodic oscillations of the CO 2 fraction in off‐gas and of the budded fraction of the cell population. A fed‐batch operation with an exponentially increasing glucose feed was started from a synchronized culture established in a chemostat. The CO 2 cycles continued for about five cycles (11 h of feed time) and then they disappeared due to gradual decay of synchrony. The fluctuations in glucose supply due to poor mixing were simulated by an intermittent supply of nutrients with a pulse‐on time of 5 s and a pulse‐off time varying from 3 to 39 s according to Monte Carlo method. Such rapid fluctuations in glucose supply during a fed‐batch fermentation immediately produced a chaotic response in CO 2 levels which indicated a complete disruption of the synchrony established previously in a chemostat. The elimination of CO 2 oscillations was consistent with the measurements of the fraction of budded cells. These results suggest that synchrony cannot be established in large‐scale stirred fermentors due to inherent concentration gradients.