Oxygen transfer in animal cell culture medium

Abstract

Both k_La and k_L measurements were carried out by an unsteady state technique at impeller speeds ranging from 1.6 to 5.8 s⁻¹ in a mechanically agitated animal cell culture vessel of working volume 1.5 L. Checks were made that the time constant of the oxygen electrode was negligible compared to the time for aeration and that the oxygen electrode reading was not a function of agitator speed in the range employed. The k_L values by surface aeration of (1.18–3.54) × 10⁻⁵ m/s and k_La values by sparged aeration of (2.8–8.5) × 10⁻⁴ s⁻¹ were found. The former are in reasonable agreement with published experimental values and the latter in accord with values estimated from published correlations based on agitator power input and aeration rate. The fluids used were water, basal medium, and basal medium supplemented with 5% (v/v) foetal calf serum; for each of these, k_L and k_La values were similar. However, the addition of silicone antifoam (6 PPM) reduced the k_La value by ca. 50%.