Escherichia coli bacteria are cultured at 35 o C and 1 atm pressure in a 500-litre fermenter
Question:
Escherichia coli bacteria are cultured at 35oC and 1 atm pressure in a 500-litre fermenter using the following medium:
Air at 25oC and 1 atm is sparged into the vessel at a rate of 0.4 m3 min-1. The dissolved oxygen tension measured using a polarographic electrode calibrated in situ in sterile culture medium is 45% air saturation. The gas flow rate leaving the fermenter is measured using a rotary gas meter as 6.3 l s-1. The oxygen concentration in the off-gas is 19.7%.
(a) Estimate the solubility of oxygen in the fermentation broth. What are your assumptions?
(b) What is the oxygen transfer rate?
(c) Determine the value of kLa.
(d) Estimate the maximum cell concentration that can be supported by oxygen transfer in this fermenter if the specific oxygen demand of the E. coli strain is 5.4 mmol g-1 h-1.
(e) If the biomass yield from the combined sugar substrates is 0.5 g g-1, is growth in the culture limited by oxygen transfer or substrate availability?
Fundamentals of Thermal-Fluid Sciences
ISBN: 978-0078027680
5th edition
Authors: Yunus A. Cengel, Robert H. Turner, John M. Cimbala