Suspension nodule culture of the Chinese herb, Rhodiola sachalinensis, in an air-lift reactor: kinetics and technical characteristics

Suspension nodule culture of Rhodiola sachalinensis was carried out in a 10 l air-lift reactor for 30 days. The biomass of 13 gdry wt/l and salidroside content of 0.45% dry wt were obtained. No foaming was observed in the reactor since the broth remained almost clear throughout the culture. The O2 transfer coefficient kLa of the culture system increased firstly then dropped during the culture cycle. The significant increase in solid holdup of the culture system is suggested to be responsible for the variation of kLa.