EFFECT OF DISSOLVED O-2 CONCENTRATION ON THE ESCHERICHIA-COLI IN A CELL-RECYCLE BIOREACTOR

In the fermentation of Escherichia coli, a ceramic membrane filter was used in conjunction with a fermenter for cell-recycle operation. The metabolic behaviour, especially the acetic acid production and the spe cific growth rate, under different concentrations of dissolved O-2 was investigated. An unstructured model was constructed, and it was shown that the observed lower cell density under low dissolved O-2 concentr ations was accompanied by large acetic aicd production. However, the c oncentration of acetic acid was not high enough to cause the observed growth inhibition, and inhibition by other metabolites under low O-2 e nvironment is suspected.