Effects of Inoculum Age and Density on hCTLA4Ig Producction in Transgenic Rice Cell Cultures

초록

Human cytotoxic T-lymphocyte antigen 4-immunoglobulin (hCTLA4Ig) was produced by sugar starvation using RAmy3D promoter in transgenic rice cell suspension cultures. Generally, it is known that initial inoculum density affects cell growth. Production of a target protein was found to be strongly dependent on inoculum age, culture medium and culture conditions. In induction phase, inoculum age is one of the most critical factors for specific productivity of cells. In this study, effects of various inoculum ages (day 2, 4, 6, and 8) and inoculum cell densities (1, 2, 3, 4, and 5 g FCW) on hCTLA4Ig production were investigated. The highest hCTLA4Ig production (47 mg/L) was achieved on day 4 in mid-exponential phase. When, in particular, the highest hCTLA4Ig production (47 mg/L) and productivity (5.22 mg/L/day) were observed, inoculum cell density was achieved with maximum production (52 mg/L) at 4 g FCW. In order to confirm the relationship between inoculum age and the productivity, differences in metabolism, effects of culture environment and cell concentration were compared. In conclusion, the highest hCTLA4Ig production could be obtained in mid-exponential phase by optimizing inoculum cell density in transgenic rice cell cultures.