Production of human secreted alkaline phosphatase in suspension and immobilization cultures of tobacco NT1 cell

The recombinant protein production by a plant cell culture offers several advantages including product safety and ease of the purification of secreted proteins and the capability of plants to correctly fold complex proteins. However, low productivity is generally a limitation of this system, caused by the denaturation and degradation of the secreted proteins due to proteolytic enzyme protease in the medium. In this study, we demonstrated that the transgenic tobacco NT1 cells were immobilized in Ca²⁺-alginate gel beads coated with a cell-free gel film, which significantly improved the productivity of the recombinant human secreted alkaline phosphatase (SEAP), about 33 times larger than that in the suspension culture. The cells immobilized in the beads were protected from hydrodynamic stress during cultivation and hence did not release the endogenous protease, which caused damage to the secreted SEAP. The immobilization culture without cell leakage could be quite effective for the production of recombinant protein.