The growth and saponin production of Platycodon grandiflorum (Jacq.) A. DC. (Chinese bellflower) hairy roots cultures maintained in shake flasks and mist bioreactor

The growth and saponin accumulation were measured in two lines of transgenic hairy roots of Platycodon grandiflorum, Pl 6 and Pl 17, cultured for 8 weeks in 250-ml shake flasks containing 50 ml of hormone-free woody plant medium supplemented with 40 g/l sucrose and in the Pl 17 line cultured for 12 weeks in a 5-l mist bioreactor containing 1.5 l of the same medium. With both methods, the growth of transgenic hairy roots was assessed as both fresh and dry weight and the biomass growth was correlated with the conductivity and sucrose uptake. The accumulation of saponins was measured and compared with that in roots derived from the field cultivation. The saponin concentrations were significantly higher in the two hairy root lines cultured in shake flasks [6.92 g/100 g d.w. (g%) and 5.82 g% in Pl 6 and Pl 17, respectively] and the line cultured in the bioreactor (5.93 g%) than in the roots derived from the field cultivation (4.02 g%). The results suggest that cultures of P. grandiflorum hairy roots may be a valuable source for obtaining saponins.