Evaluation of spent medium recycle and nutrient feeding strategies for recombinant protein production in the insect cell-baculovirus process

In the production of recombinant proteins by the insect cell-baculovirus pr ocess, fresh medium renewal prior to virus infection has been an effective measure for maintaining high protein yields. The spent medium used in the g rowth stage may still be unexhausted and can be reused for cell growth. In this study, we exercised the recycle of a spent insect cell medium for cell growth and recombinant protein production. It was found that the spent med ium collected from a culture close to the stationary growth phase could pro vide full support for insect cell growth through another batch culture afte r fortified with suitable nutrients (yeastolate, glucose and glutamine) and a small fraction (15-20%) of fresh medium. The specific and volumetric pro tein yields with cells grown in the recycled spent medium were in most case s similar to those with cells grown in fresh medium. Protein yields on per unit volume of fresh medium in the process incorporating spent medium recyc le compared favourably with that achieved in a batch or fed-batch process. Spent medium recycle is hence a feasible alternative for the insect cell cu lture-baculovirus process. (C) 1998 Elsevier Science B.V. All rights reserv ed.