We have used the initial-rate approach to characterize changes in the glucose consumption kinetics of baculiovirus-infected Spodoptera frugiperda clone 9 (Sf9) cells with the progression of the infection process. The specific glucose consumption rate (q(G)) of cultured baculovirus-infected Sf9 cells was measured at 4, 8, 12, 16, and 24 h postinfection (h.p.i.) in media containing 4-35 mM glucose. Higher medium glucose concentrations resulted in higher final extracellular virus and recombinant beta-galactosidase yields. q(G) was related to the extracellular glucose concentration by means of a Michaelis-Menten relationship. The apparent Michaelis-Menten constant (K-m) for glucose consumption was found not to change significantly during the progression of the infection process, and remained between 6.2 and 7.2 mM. However, the maximal specific glucose consumption rate (q(Gmax)) was found to rapidly increase after infection, peaking at 16 h.p.i. at a value four times that for uninfected Sf9 cells. The kinetic analysis of glucose consumption rates in baculovirus-infected Sf9 cells presented here will aid in the optimal design and operation of bioreactor systems for the large-scale production of recombinant products from the bacullovirus/insect cell system.