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Control of ammonium concentration in Escherichia coli fermentations
Author(s) -
Thompson B. G.,
Kole M.,
Gerson D. F.
Publication year - 1985
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.260270610
Subject(s) - ammonium , fermentation , ammonia , chemistry , ammonium sulfate , effluent , escherichia coli , chromatography , food science , biochemistry , environmental engineering , organic chemistry , environmental science , gene
Abstract A control system has been devised for the maintenance of stable ammonium concentrations throughout a fedbatch fermentation. The control system is based on an ammonia gas‐sensing electrode that monitors a pH‐adjusted effluent stream from the fermentor. To overcome the time lag between the fermentor and the electrode, feedback control included metered flows of ammonium to both the fermentor and the electrode vessel. The system was used to study the growth of Escherichia coli B (ATCC 11303) at controlled ammonium concentrations of 5 to 200m M . Apparent specific growth rates, biomass and protein production, and glucose yields were essentially constant from 5 to 170m M . Above 170m M ammonium growth was inhibited. As ammonium concentration decreased from 170 to 5m M , ammonium yields increased from 1 to 24 g cell dry wt/g ammonium utilized. The results demonstrate that control of ammonium concentrations at levels so low that ammonium would be exhausted in batch fermentations can significantly increase overall ammonium yields.