Semicontinuous processes for anthraquinone production with immobilized Cruciata glabra cell cultures in a three-phase system

A semicontinuous bioprocess with simultaneous use of immobilized plant cells and in situ product extraction in a second liquid phase was developed to enhance the productivity of secondary metabolites and to overcome current limitations of plant cell cultures, such as slow metabolic rate, low product yield, and sensitivity to shear stress. Production of anthraquinones with Cruciata glabra was selected as a model system. The effects of cell immobilization and a second liquid phase using the triglyceride Miglyol were investigated in suspended and immobilized plant cells in batch operation as well as in semicontinuous processes. The concurrent use of cell immobilization and Miglyol improved the specific productivity of anthraquinones 5.5-fold. Continuous removal of metabolites from the solid phase by addition of a second liquid phase has been found to stimulate the biosynthetic capacity leading to overproduction and secretion of anthraquinones up to 58%. Semicontinuous process operations enabled a total 49-fold increase in specific productivity with selected 'replacement rates'.