CONTINUOUS INSECT-CELL (SF-9) CULTURE WITH AERATION THROUGH SPARGING

The continuous growth of Spodoptera frugiperda Sf-9 cells in a 250-ml blown-glass jacketed spinner flask under a direct air sparging environ ment was investigated. Even at 220 ml working volume (about 90% of tot al volume), this spinner flask provided good mixing and oxygenation as demonstrated by a higher cell density compared with fermenter culture s. This eliminates a common limitation of the traditional spinner flas k, namely much lower cell density at high working volume. Furthermore, this spinner flask has been run with Sf-9 cell culture at five differ ent dilution rates and two different air sparging rates at steady stat e, demonstrating its utility in research applications where cell size, metabolic activity and environmental conditions can be constantly mai ntained. In addition to demonstrating the utility of the reactor, thre e novel points are made in this report. First, cell density in continu ous cultures is increased significantly due to a high agitation rate a nd, especially, air sparging rate, which is seldom used in animal cell or insect cell culture. Second, there is no apparent difference in th e specific death rate at two different sparging rates (0.0093 vvm and 0.0125 vvm). Finally, we have maintained Sf-9 cells for more than 4 mo nths in a continuous culture using a serum-free medium without loss of recombinant protein expression in infected cells.