Effects of Inoculum Age on Cell Growth and hCTLA4Ig Production in Transgenic Rice Cell Cultures

초록

Human cytotoxic T-lymphocyte antigen 4-immunoglobulin (hCTLA4Ig) was produced using RAmy3D promoter which is a strong promoter induced by sugar starvation in transgenic rice cell suspension cultures. hCTLA4Ig can be produced in twostage cultures. Growth and production phases should be separated to enhance the production. Production of a target protein was found to be strongly dependent on inoculum age, culture medium and culture conditions in plant cell cultures. Inoculum age is an important factor for enhancing specific productivity of cells. In this study, variable incubation times were compared between production phase (day 2, 4, 6 and 8) and growth phase (day 2, 4, 6 and 8), respectively. At growth phase, four-dayold cells as an inoculum reached higher cell mass compared to that of eight-day-old cells in stationary phase. Overall carbon source and amino acid were consumed at higher rates during the early exponential phase than stationary phase. At production phase, the highest productivity and cell viability were achieved with the inocula from early exponential phase (four-day-old cells). In conclusion, early inoculum age could improve hCTLA4Ig productivity and viability in transgenic rice suspension cell cultures.