The effect of microsparged aeration in mammalian cell bioreactor on the oxygen transfer rate and cell viability was studied. The microspargers with different micron-sized pores were used to supply oxygen to the medium. The oxygen transfer coefficients (kLa) measured in the bioreactor were markedly increased due to the increase of the contacting area between air bubbles and liquid medium when the pore size of microsparger was decreased. When the impellers of two different types(square-pitch marine impeller and 45°pitched flat blade impeller) were used for agitation, the kLa values were slightly higher with the marine impeller than with the blade impeller. However, the mixing time was rather shorter with the blade impeller than with the marine impeller. The detrimental effect of direct gas sparging with microsparger on mammalian cells was investigated in bubble columns with various air flow rates and bubble sizes. The first-order cell death rate constant(kd) was shown to be directly proportional to the air flow rate and inversely proportional to the bubble size. During the cultivation of hybridoma cells using microsparger with the pore size of 0.5μm in the mammalian cell bioreactor, the continuous sparging caused the cell death and suppressed the cell growth. However, cells grew normally and cell viability was maintained above 90% in the logarithmic phase when the air was intermittently sparged in order to maintain the dissolved oxygen level above 20%.
