RECOMBINANT BETA-GALACTOSIDASE PRODUCTION IN SERUM-FREE MEDIUM BY INSECT CELLS IN A 14-L AIRLIFT BIOREACTOR

Spodoptera frugiperda (Sf9) insect cells were successfully cultured in serum-free medium in a 14-L airlift bioreactor. Cell densities as high as 1 X 10(7) cells/mL were achieved with specific growth rates of approximately 0.0286 h-1 (doubling time of 24 h). This system was also used to demonstrate the expression of a reported gene, beta-galactosidase (beta-gal), when cells were infected with a recombinant baculovirus. Approximately 0.33 mg of beta-gal/mL (i.e., 104 000 units/mL) of medium were obtained at the 14-L scale, while about 0.95 mg of beta-gal/mL (i.e., 285 000 units/mL) of medium were obtained in small-scale shaker flasks. The difference was attributed to a suboptimal infection in the large scale. Specific oxygen consumption rates decreased from 5.58 x 10(-17) mol O2/cells in early exponential growth to 3.13 x 10(-17) mol O2/cell-s at 3 days post-infection.