Continuous β-galactosidase production with a recombinant baculovirus insect-cell system in bioreactors

Insect cells were exploited to produce bacterial β-galactosidase by infecting them with a recombinant nuclear polyhedrosis virus (baculovirus) of Autographa californica. The insect cells were cultured in a continuous stirred tank reactor (CSTR) and led to a second CSTR where they were infected with a recombinant virus in which the lacZ gene from Escherichia coli was inserted. In the effluent of the production reactor, maximum activities of 15 units β-galactosidase per 10 6 cells were measured. For about 25 d β-galactosidase production remained constant, but then rapidly declined. This drop was due to a decrease in production of active β-galactosidase rather than to inactivation of this enzyme. It was concluded that the reduced production was due to reduced polyhedrin promoter-driven synthesis.