Oxygen transfer in animal cell culture medium

Abstract

Both k(L)a 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) x 10(-5) m/s and k(L)a values by sparged aeration of (2.8-8.5) x 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(L)a values were similar. However, the addition of silicone antifoam (6 PPM) reduced the k(L)a value by ca. 50%.

On-line measurement of oxygen uptake in cell culture using the dynamic method

“…Surface transfer k, computed from these data using Equation (4) was 13-29 cm/h. This compares well with reported values (Lavary and Nienow, 1987). The oxygen uptake calculated by the on-line dynamic method was corrected by subtracting the contribution from surface aeration.…”

“…The dissolved oxygen probe time constants can be neglected in comparison to the process response under the agitation conditions typically employed (Lavary and Nienow, 1987). From the literature (Boraston et al, 1982), no detrimental effect of DO cycling on cell growth and performance is expected in the range of operation (25-60% of saturation).…”

Scale‐up analysis for a CHO cell culture process in large‐scale bioreactors

“…Thus, the test medium is composed of 6.4 g L À1 sodium chloride, 2.0 g L À1 sodium bicarbonate, and 1.0 g L À1 Pluronic-F68. It was reported in literature that the additive of serum-free cell culture medium to distilled water only had negligible impact on k L a value at the low agitation speed (100 rpm) (Lavery and Nienow, 1987). Therefore, the measurement from the test medium should represent that from the actual cell culture medium.…”

“…The use of a test medium in this study instead of the actual cell culture medium is due to the concern of microbial contamination in our cGMP facilities (5,000-L bioreactors). Since sodium carbonate (Na 2 CO 3 ) is a critical buffering reagent for pH control (Langheinrich and Nienow, 1999) and Pluronic-F68 lowers k L a significantly (Lavery and Nienow, 1987), the same concentrations of sodium bicarbonate and Pluronic-F68 in cell culture medium were used in the test medium. The additional sodium chloride was also used in the test medium to maintain the similar viscosity and bubble coalescence as the actual cell culture medium.…”

Oxygen transfer rates in a mammalian cell culture bioreactor equipped with a cell‐lift impeller

“…However, this has been reported elsewhere. ' The true mass transfer performance of the gas exchange impeller (k,a), can be evaluated by subtracting the surface aeration contribution (kLa), from the kLa values measured for the whole reactor and by multiplying this difference by a correction factor (V,/V,-) according to the following equation (3) This volume correction factor takes into account the fact that the measured k,a value was based on the total volume of liquid in the reactor (V,) whereas only the volume of Values of k,a for the culture medium supplemented with 5%…”