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Bioprocess Engineering

, Volume 18, Issue 3, pp 171–180 | Cite as

Substrate gradient formation in the large-scale bioreactor lowers cell yield and increases by-product formation

  • F. Bylund
  • E. Collet
  • S.-O. Enfors
  • G. Larsson
Article

Abstract

A heterogeneous micro-environment was identified in a 12 m3 bioreactor with a height-to-diameter ratio of 2.5. The reactor was aerated by a ring sparger and stirred by three Rushton turbines. E. coli cells were cultivated in minimal medium to a cell density in the order of 30 g/l. Samples of glucose, the growth limiting component fed to the process, were taken at three levels in the bioreactor (top/middle/bottom). These showed that glucose concentration declined away from the feedpoint. The gradients depended on the mixing characteristics of the feedpoint, and concentrations of up to 400 times the mean value were found when feed was added to a relatively stagnant mixing zone. This resulted in up to 20% lower biomass yield compared to the bench scale. Gradients also affected the by-product formation, resulting in acetate formation in the large-scale bioreactor. IPTG induction of a recombinant protein was shown to influence important cell parameters and considerably increased the yield of carbon dioxide per glucose added, indicating an increased maintenance. The product formation rate was, however, not notably affected by the scale-up.

Keywords

IPTG Biomass Yield Cell Yield Lower Biomass IPTG Induction 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag Berlin Heidelberg 1998

Authors and Affiliations

  • F. Bylund
    • 1
  • E. Collet
    • 1
  • S.-O. Enfors
    • 1
  • G. Larsson
    • 1
  1. 1.Department of Biochemistry and Biotechnology, Royal Institute of Technology, S-100 44 Stockholm, SwedenSE

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