EFFECT OF PREINDUCTION SPECIFIC GROWTH-RATE ON SECRETION OF GRANULOCYTE-MACROPHAGE COLONY-STIMULATING FACTOR BY ESCHERICHIA-COLI

The effect of preinduction specific growth rate on the rate of synthes is and processing of granulocyte macrophage colony stimulating factor (GMCSF) secreted by Escherichia coli was investigated. A chemostat was used to explore preinduction growth rates ranging from 0.038 to 0.2/h . The maximum yields of both total GMCSF and processed GMCSF were foun d to occur at a preinduction growth rate of 0.13/h. It was also discov ered that if the postinduction feed rate is reduced at a preinduction growth rate near 0.13/h, then the same amount of processed GMCSF is fo rmed, but no unprocessed GMCSF is produced. It was hypothesized that t he rate of synthesis of total GMCSF increases with an increased preind uction specific growth rate, but translocation across the cytoplasmic membrane and processing is rate-limiting. Increased degradation of GMC SF during induction at higher preinduction specific growth rates decre ased the amount of GMCSF produced.