EFFECT OF NITROGEN-SOURCE ON CELL-GROWTH AND PRODUCTION OF GINSENG SAPONIN AND POLYSACCHARIDE IN SUSPENSION-CULTURES OF PANAX NOTOGINSENG

The effects of the nitrate to ammonium ratio on the cell growth, the p roduction of ginseng saponin (secondary metabolite) and polysaccharide (primary metabolite), as well as consumption of major nutrients by su spension cultures of Panax notoginseng cells were investigated at a to tal nitrogen (N) of 60 mM in a 250-mL Erlenmeyer flask. The results in dicate that the ratio of nitrate to ammonium had a great influence on the cell growth and consumption of carbon and N sources. It was found that biosynthesis of saponin was more susceptible to the ratio of NO3- /NH4+ than that of polysaccharide. Ammonium was unfavorable to saponin formation. The maximum production of ginseng saponin and polysacchari de was attained when nitrate was the sole N source. The effect of tota l N amount (using nitrate as the sole N source) on the cell cultures w as also studied, and the result shows that the dry cell weight was inc reased from 4.9 to 10.9 g/L with increase of initial nitrate concentra tion from 0 to 60 mM. The relationship between initial nitrate concent ration (including both intracellular and medium nitrate) and specific cell growth rate based on active biomass could be described by Monod e quation, in which the kinetic parameters mu(max) and K-s were determin ed to be 0.066 d(-1) and 4.84 mM, respectively. The maximum production of ginseng saponin and polysaccharide was 0.85 and 1.59 g/L, respecti vely, with initial nitrate concentration of 60 mM.