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Process development with nitrogenase‐producing Escherichia coli C‐M74 (pUS1) CellS
Author(s) -
Ahlmann N.,
Schügerl K.
Publication year - 1991
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.260381002
Subject(s) - escherichia coli , nitrogenase , fermentation , biochemistry , chemostat , klebsiella pneumoniae , biology , bacteria , strain (injury) , microbiology and biotechnology , chemistry , food science , nitrogen fixation , gene , genetics , anatomy
Abstract A process for the continuous fermentation of the genetically modified, nitrogenase‐producing Escherichia coli C‐M74 (pUS1)‐strain has been developed. This strain, which is able to fix molecular nitrogen, has the nif genes of the bacterium Klebsiella pneumoniae . Cell growth and nitrogenase activity of the enzyme have been optimized both in batch and continuous fermentations. For the fermentations, trial runs were performed by cultivating the E. coli cells in 50‐ml culture bottles. The medium composition was varied in order to provide high biomass production and nitrogenase activity. For an effective fermentation control, an on‐line analysis was built up for the substrates ammonium and glucose. Other medium components such as ampicillin, citric acid, acetic acid, nitrogenase activity, and protein were measured by using different off‐line methods. Modern optical methods like in‐line microfluorometry for monitoring the culture fluorescence and laser flow cytometry for the estimation of DNA and protein content were also employed. Plasmid stability was also determined.