Hematopoietic cells used in cancer treatment are cultured at 37 o C in an 8.5-cm diameter bioreactor
Question:
Hematopoietic cells used in cancer treatment are cultured at 37oC in an 8.5-cm diameter bioreactor with working volume 500 ml. The culture fluid is mixed using a stirrer speed of 30 rpm. The reactor is operated at ambient pressure.
(a) The dissolved oxygen tension is controlled at 50% air saturation using surface aeration only. A 50:20:30 mixture of air, oxygen, and nitrogen is passed at a fixed flow rate through the headspace. The specific oxygen uptake rate for hematopoietic cells is 7.7 X 10-12 g cell-1 h-1 and the cell concentration is 1.1 X 109 cells l-1. Estimate the value of kLa for surface aeration.
(b) Instead of surface aeration, the bioreactor is sparged gently with air. When the dissolved oxygen tension is maintained at the critical level of 8% air saturation, the cell concentration is 3.9 X 109 cells l-1. What is the kLa for bubble aeration?
(c) Surface aeration is preferred for this shear-sensitive culture, but the surface kLa needs improvement. For the gassing conditions applied in (a), estimate the vessel diameter required for surface aeration to achieve the same kLa obtained with sparging. What are your assumptions?
Molecular Cell Biology
ISBN: 978-1429234139
7th edition
Authors: Harvey Lodish, Arnold Berk, Chris A. Kaiser, Monty Krieger, Anthony Bretscher, Hidde Ploegh, Angelika Amon, Matthew P. Scott