Application of bioreactor system for large-scale production of Eleutherococcus sessiliflorus somatic embryos in an air-lift bioreactor and production of eleutherosides

Embryogenic callus was induced from leaf explants of Eleutherococcus sessiliflorus cultured on Murashige and Skoog (MS) basal medium supplemented with 1 mg l(-1) 2,4-dichlorophenoxyacetic acid (2,4-D), while no plant growth regulators were needed for embryo maturation. The addition of 1 mg l(-1) 2,4-D was needed to maintain the embryogenic culture by preventing embryo maturation. Optimal embryo germination and plantlet development was achieved on MS medium with 4 mg l(-1) gibberellic acid (GA(3)). Low-strength MS medium (1/2 and 1/3 strength) was more effective than full-strength MS for the production of normal plantlets with well-developed shoots and roots. The plants were successfully transferred to soil. Embryogenic callus was used to establish a suspension culture for subsequent production of somatic embryos in bioreactor. By inoculating 10 g of embryogenic cells (fresh weight) into a 3l balloon type bubble bioreactor (BTBB) containing 2l MS medium without plant growth regulators, 121.8 g mature somatic embryos at different developmental stages were harvested and could be separated by filtration. Cotyledonary somatic embryos were germinated, and these converted into plantlets following transfer to a 3l BTBB containing 2l MS medium with 4 mg l(-1) GA3. HPLC analysis revealed that the total eleutherosides were significantly higher in leaves of field grown plants as compared to different stages of somatic embryo. However, the content of eleutheroside B was highest in germinated embryos. Germinated embryos also had higher contents of eleutheroside E and eleutheroside E1 as compared to other developmental stages. This result indicates that an efficient protocol for the mass production of E. sessiliflorus biomass can be achieved by bioreactor culture of somatic embryos and can be used as a source of medicinal raw materials.