PRODUCTION OF RECOMBINANT HUMAN GRANULOCYTE-COLONY-STIMULATING FACTORIN HIGH CELL-DENSITY YEAST CULTURES

The recombinant human granulocyte-colony-stimulating factor (rhG-CSF) was synthesized in a fusion protein using a GAL1-10 UAS in recombinant Saccharomyces cerevisiae and the intracellular KEX2 cleavage led excr etion of mature rhG-CSF into the extracellular culture broth. The reco mbinant yeast growth in fed-batch cultures was controlled by precise c omputer-aided medium feed. The optimal C/N ratio in preinduction (gluc ose/Casamino acids) and postinduction (galactose/yeast extract) feed m edia was determined at 3 and 2, respectively. The final rhG-CSF and ce ll concentration was more than 60 mg/L and 70 g/L, respectively, with around 90% plasmid stability and negligible ethanol accumulation. Comp aring the cell growth between the hG-CSF+ and hG-CSF recombinant strai ns shows that the cloned gene product does not hamper the host cell gr owth.