Isoflavone production in Cyclopia subternata Vogel (honeybush) suspension cultures grown in shake flasks and stirred-tank bioreactor.

Suspension cultures of the endemic South-African plant Cyclopia subternata were established for the first time and evaluated for the presence of isoflavones. The influence of light, as well as medium supplementation strategies with phenylalanine, casein hydrolysate and coconut water on biomass growth and isoflavone production were examined. The highest levels of 7-O-β-glucosides of calycosin, pseudobaptigenin and formononetin (275.57, 125.37 and 147.28 mg/100 g DW, respectively) were recorded for cultures grown in the absence of light, whereas coconut water substantially promoted biomass growth. Cell suspensions were subsequently grown in the 2-l stirred-tank bioreactor. Maximum productivity of 7-O-β-glucosides of calycosin, pseudobaptigenin and formononetin (0.96, 0.44 and 0.22 mg l(-1) day(-1), respectively) in bioreactor-cultivated cells was obtained for biomass grown in the dark and supplemented with coconut water. The results indicate that C. subternata suspension cultures can be utilised for the production of the specified isoflavone derivatives absent in the intact plant.