Enhanced growth of Sf-9 cells to a maximum density of 5.2 x 10(7) cells per mL and production of beta-galactosidase at high cell density by fed batchculture

Significant improvement in cell growth and protein production has been achi eved in Sf-9 insect cell cultures using pulse additions of multicomponent n utrient feed concentrates (Bedard et at., 1994; Chan et al., 1998). The pre sent work focuses on investigating an alternative feeding strategy wherein the nutrients are fed in a semi continuous manner. Fed batch culture experi ments were carried out to compare the two different feeding strategies, pul se and semi continuous and a process developed to achieve a cell density of 5.2 x 10(7) cells/mL of Sf-9 cells in a 3.5 L bioreactor. Production of re combinant protein p-galactosidase was carried out by infecting the cells wi th baculovirus at a MOI of 10 at cell densities of 17 x 10(6) cells/mL. Spe cific productivity could be maintained at cell densities as high as 14 x 10 (6) cells/mL. The results presented indicate that the feeding method can pr ovide significant improvements in the performance with a reduction in the a mount of total nutrients added. On-line monitoring of the culture using the capacitance probe showed that the capacitance probe can be used successful ly to monitor the biomass and infection process even at higher cell densiti es. (C) 2000 John Wiley & Sons, Inc. Biotechnol Bioeng 68: 381-388, 2000.