Comparison of oxygen supply methods for cultures of shear-stress sensitive organisms including animal cell culture.

In animal cell culture, oxygen supply sometimes limits cell growth. Therefore, four oxygen supply methods (free surface aeration, porous Teflon tubing, perfluorocarbon addition and external aerator) were compared in terms of oxygen transfer rate for suspension culture of animal cells. Oxygen transfer rate with the free surface aeration was dependent on the vertical position of the impeller and the stirred Reynolds number for h/HL greater than 0.35, but no effect of the impeller position was observed for h/HL less than 0.35. The relationship between the Reynolds and Sherwood numbers could be expressed by simple correlations. These correlations could also be applied to oxygen transfer using porous Teflon tubing. When oxygen was supplied with perfluorocarbon saturated with air, the overall mass transfer coefficient KL was estimated to be about 9.0 X 10(-3) cm s-1, which was five-fold greater than that of the surface aeration. Maximum cell densities which would be supported by four methods were calculated from values of KLa for different sizes of fermentor assuming that oxygen supply would be the rate-limiting factor in animal cell culture.