Enhancement of ginseng saponin production in suspension cultures of Panax notoginseng: Manipulation of medium sucrose

The effect of initial sucrose concentration (i.e. 20, 30, 40 and 60 g l(-1)) was investigated in suspension cultures of Panax notoginseng for production of ginseng saponin (secondary metabolite) and polysaccharide (primary metabolite). The final dry cell weight was increased from 8.9 to 11.9 g l(-1) with an increase of initial sucrose concentration from 20 to 40 g l(-1), but an even higher sucrose concentration of 60 g l(-1) seemed to repress the cell growth. The specific growth rate based on active biomass was reduced from 0.084 to 0.067 day(-1) with an increase of initial sucrose from 20 to 60 g l(-1). The initial sucrose amount also had a significant effect on sugar metabolism as well as consumption of nitrate and phosphate. Furthermore, it was found that a high sugar level was favorable to the synthesis of ginseng saponin, which may be due to the high osmotic pressure and reduced nutrient uptake (especially nitrate) under these conditions. The content of ginseng polysaccharide was not apparently affected by initial sucrose levels. The maximum production of ginseng saponin (0.86 g l(-1)) and polysaccharide (1.98 g l(-1)) was achieved at an initial sucrose concentration of 40 g l(-1) on day 26. Based on the above findings, a sugar feeding strategy was formulated to enhance the saponin accumulation by P. notoginseng cells. The highest saponin production of 1.77 g l(-1) (on day 26) was obtained by intermittent sugar feeding during cultivation; the production and productivity of ginseng saponin increased 2.3- and 2.1-fold compared with those of control, respectively.