Estimation of dissolved carbon dioxide stripping in a large bioreactor using model medium

Dissolved carbon dioxide (dCO2) accumulation is one of the most serious problems in the scale-up of industrial cell culture. To predict the effects of dCO2 stripping in different culture conditions and at different scales, we examined a method of estimation of dCO2 stripping using a model medium. The operational parameters (e.g., sparging and agitation rate) and the size of the bioreactor (working volume: 80 L, 500 L, 2000 L; aspect ratio: 1.0 ∼ 1.6) were varied, and the model medium was prepared by adjusting pH, density, viscosity, surface tension, and buffer conditions. dCO2 stripping efficiency was evaluated using the index kLaCO2, which was defined in accordance with the volumetric oxygen transfer coefficient kLa. The model medium exhibited dCO2 stripping behavior similar to real culture medium in all experimental conditions tested. It is expected that the use of the model medium to estimate dCO2 stripping in real cultures will be valuable for determining the culture conditions in bioreactors in scale-up.