BUBBLE BED REACTOR - A REACTOR DESIGN TO MINIMIZE THE DAMAGE OF BUBBLE AERATION ON ANIMAL-CELLS

A new bubble aeration system was designed to minimize cell killing and cellular damage due to sparging. The residence time of the bubbles in the developed bubble bed reactor was prolonged dramatically by floati ng them in a countercurrent produced by an impeller. The performance o f the new reactor bubble aeration system, implemented in a laboratory reactor, was tested in dynamic aeration experiments with and without c ells. An efficiency up to 95% in oxygen transfer could be achieved, wh ich enables a much lower gas flow rate compared with conventional bubb le aeration reactors. The low gas flow rate is important to keep cell damage by bubbles as low as possible. A laser light sheet technique wa s used to find the optimal flow pattern in the reactor. The specific p ower dissipation of the impeller is a good measure to predict cell dam age in a turbulent flow. Typical values for the power dissipation meas ured in the bubble bed reactor were in the range of 0.002 to 0.013 W/k g, which is far below the critical limit for animal cells. The growth of a hybridoma cell line was studied in cell cultivation experiments: A protein-free medium without supplements such as serum or Pluronic F6 8 was used to exclude any effect of cell-protecting factors. No differ ence in the specific growth rate and the yield of the antibodies was o bserved in cells grown in the bubble bed reactor compared with those g rown in bubble-free surface aeration in the spinner flask. In contrast to the spinner flask, however, the bubble bed reactor design could be scaled up. (C) 1994 John Wiley and Sons, Inc.