Effects of oxygen partial pressure on cell growth and ginsenoside and polysaccharide production in high density cell cultures of Panax notoginseng

The effects of oxygen partial pressure (pO2), within the range 10.6–36.5 kPa, on high density cell cultures of Panax notoginseng were investigated in a bioreactor. A pO2 of 21.3–29.3 kPa was found optimal for the production of cell mass, ginseng saponin and polysaccharide with corresponding values of 24, 1.75 and 3.0 g l−1 on Day 15, respectively. A low pO2 was unfavorable to the cell cultures due to oxygen limitation. High pO2 (36.5 kPa) inhibited cell growth and reduced the production of ginseng saponin and polysaccharide, which was due to the detrimental effect of oxidative burst. The effect of pO2 on heterogeneity of ginsenosides produced in the cell cultures was also studied. A high pO2 (at 36.5 kPa) stimulated Rb1 biosynthesis in the initial stage of cultivation, while a low pO2 (at 10.6 kPa) inhibited Rg1 and Rb1 formation during cultivation.