Further studies related to the scale-up of high cell density Escherichia coli fed-batch fermentations: the additonal effect of a changing micro-environment when using aqueous ammonia to control pH

Helen Onyeaka, Alvin Nienow, Christopher Hewitt

Research output: Contribution to journalArticle

60 Citations (Scopus)

Abstract

In this work, we report on the further development of the scale-down, two-compartment (STR + PFF) experimental simulation model. For the first time, the effect on high cell density Escherichia coli fed-batch fermentations of a changing microenvironment with respect to all three of the major spatial heterogeneities that may be associated with large-scale processing (pH, glucose, and dissolved oxygen concentration) were studied simultaneously. To achieve this, we used traditional microbiological analyses as well as multiparameter flow cytometry to monitor cell physiological response at the individual cell level. It was demonstrated that for E. coli W3110 under such conditions in a 20 m(3) industrial fed-batch fermentation, the biomass yield is lower and final cell viability is higher than those found in the equivalent well-mixed, 5L laboratory scale case. However, by using a combination of the well-mixed 5L stirred tank reactor (STR) with a suitable plug flow reactor (PFR) to mimic the changing microenvironment at the large scale, very similar results to those in the 20 m(3) reactor may be obtained. The similarity is greatest when the PFR is operated with a mean residence time of 50 sec with a low level of dO(2) and a high glucose concentration with either a pH of 7 throughout the two reactors or with pH controlled at 7 in the STR by addition into the PFR where the pH is > 7. (C) 2003 Wiley Periodicals.
Original languageEnglish
Pages (from-to)474-484
Number of pages11
JournalBiotechnology and Bioengineering
Volume84
Issue number4
Early online date17 Oct 2003
DOIs
Publication statusPublished - 20 Nov 2003

Keywords

  • viability
  • membrane integrity
  • membrane potential
  • Escherichia coli
  • fed-batch
  • scale-up
  • flow cytometry
  • microenvironment
  • high cell density
  • pH

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