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Non-disruptive method to estimate the volumetric oxygen mass transfer coefficient (kLa) throughout a fermentation
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  • Elliot Mercado,
  • Sarah Mbiki,
  • Sarah Harcum ,
  • Jordon Gilmore
Elliot Mercado
Clemson University

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Sarah Mbiki
Clemson University
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Sarah Harcum
Clemson University
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Jordon Gilmore
Clemson University
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Abstract

In the biopharmaceutical industry, accurate prediction of the oxygen uptake rate (OUR) by the cells is critical to understanding cell health. Accurate estimation of the oxygen transfer rate (OTR) presents a significant challenge in predicting OUR, and OTR is dependent on the volumetric oxygen mass transfer coefficient (kLa). Often kLa is assumed to be constant throughout a fermentation and estimated from experiments using no cells and in a buffer solutions. Yet, it is well-known that additions (i.e., glucose, base, and antifoam), cell secretions, and stir speed markedly effect kLa. Currently, there are three standard methods used to estimate kLa; however, all three have significant issues. This rapid communication describes a novel, non-disruptive method to estimate kLa by modulating the gas flow rate. This approach allowed accurate kLa estimates at multiple times throughout Escherichia coli batch fermentations using a non-disruptive technique, thus lowering the risk of losing a fermentation due to inadequate oxygenation.