Enhanced production of hGM-CSF by medium exchange in transgenic Oryza sativa L. suspension cultures

Human granulocyte-macrophage colony-simulating factor (hGM-CSF) was produced by transgenic rice cells using the RAmy3D promoter. Since the cultures were induced to express recombinant proteins by sugar starvation, the culture period should be divided into the growth and production stages. For the successful production of hGM-CSF using this induction method, the optimum time for the medium exchange was examined. When the culture medium was exchanged days 6 after inoculation, the maximum concentration of extracellular hGM-CSF was 16.0 mg l −1, which was obtained at the 10th day after induction, and was 2.88-fold increased compared to that of the control without medium exchange. In terms of the specific productivity, 3.56 mg gDCW −1 day −1 was obtained, which was 4.35-fold higher than that of the control.