Effect of CO 2 on uninfected S f‐9 cell growth and metabolism

A problem in the mass production of recombinant proteins and biopesticides using insect cell culture is CO 2 accumulation. This research investigated the effect of elevated CO 2 concentration on insect cell growth and metabolism. Spodoptera frugiperda Sf‐9 insect cells were grown at 20% air saturation, 27 ° C, and a pH of 6.2. The cells were exposed to a constant CO 2 concentration by purging the medium with CO 2 and the headspace with air. The population doubling time (PDT) of Sf‐9 cells increased with increasing CO 2 concentration. Specifically, the PDT for 0‐37, 73, 147, 183, and 220 mm Hg CO 2 concentrations were 23.2 ± 6.7, 32.4 ± 7.2, 38.1 ± 13.3, 42.9 ± 5.4, and 69.3 ± 35.9 h (n = 3 or 4, 95% confidence level), respectively. The viability of cells in all experiments was above 90%, i.e., while increased CO 2 concentrations inhibited cell growth, it did not affect cell viability. The osmolality for all bioreactor experiments was observed to be 300–360 mOsm/kg, a range that is known to have a negligible effect on insect cell culture. Elevated CO 2 concentration did not significantly alter the cell specific glucose consumption rate (2.5–3.2 × 10 −17 mol/cell s), but slightly increased the specific lactate production rate from −3.0 × 10 −19 to 10.2 × 10 −19 mol/cell s. Oxidative stress did not contribute to CO 2 inhibition in uninfected Sf‐9 cells as no significant increase in the levels of lipid hydroperoxide and protein carbonyl concentrations was discovered at elevated CO 2 concentration. © 2016 American Institute of Chemical Engineers Biotechnol. Prog. , 32:465–469, 2016