Cultures of Nicotiana tabacum cells immobilized in calcium alginate gel beads coated with cell-free gel film

Nicotiana tabacum cells were immobilized in the Ca-alginate gel beads coated with the cell-free get film and then cultivated in the flask. The effects of the coating film thickness on intraparticle cell growth and cell leakage were investigated. The beads with the coating film of a desired thickness can be prepared by controlling the amount of free Ca²⁺ in the core beads. The optimum thickness for preventing cell leakage without inhibiting intraparticle cell growth was determined. The productivity of the phenolics, which was one of the secondary metabolites of tobacco cells, for the immobilization cultures was compared with that for the suspension culture. The phenolics production and release to the medium seemed to be promoted by the immobilization. The immobilization culture using the coated beads was very effective in promoting the extracellular productivity of the phenolics as well as preventing cell leakage. The immobilization method was applied to the culture system using an airlift bioreactor with a draft tube. Cell leakage was completely prevented throughout the 25-day cultivation without inhibiting cell growth.