Effects of plant growth regulators on cell growth and ginsenoside saponin production by suspension cultures of Panax quinquefolium

To understand the culture characteristics of suspended cells of Panax quinquefolium strain Q91625 in a shake flask, the dynamic changes of various parameters, such as pH, conductivity, wet and dry cell concentrations, and the consumption of major nutrients during cultivation were first investigated. Then, the effects of plant growth regulators, i.e,, 2,4-dichlorophenoxyacetic acid (2,4-D), indole-3-butyric acid (IBA), and kinetin (KT), on the cell growth, saponin production and nutrient utilization by the cultured cells were focused on. The results indicate that the highest content of ginsenoside saponins, i.e., 10.9% by dry weight, a relatively high production and productivity of saponins, being 602 mg l(-1) and 20.1 mg l(-1) d(-1) respectively, and the highest product yield, i.e., 57.3 mg g(-1), were reached in the cell cultures with a combination of the growth regulators of 2.5 mg l(-1) IBA and 0.1 mg l(-1) KT without addition of 2,4-D. This amount of saponin content is 70% higher than previously reported in the cell suspension cultures, and also 68% higher than that obtained from the naturally cultivated 4-6-year-old plant. In addition, it was also understood that in the cultures with a relatively high production of saponins, the utilization of the major nutrients, i.e., sugar, phosphate, ammonium, and nitrate, was at a relatively high level; and in the cultures with a relatively high growth rate of the cells, the nitrate utilization seemed to be much greater than in the other cases.