Alkaloid production by plant cell cultures of Holarrhena antidysenterica: II. Effect of precursor feeding and cultivation in stirred tank bioreactor.

Precursor feeding strategy for increasing the yield of conessine, a steroidal alkaloid of Holarrhena antidysenterica, was established in cell suspension culture. A total of 50 mg/L added cholesterol was converted into 43 mg/L of alkaloid, 90% of which constituted the conessine. By applying the precursor feeding policy to the cell suspension culture in modified Murashige and Skoog (MS) medium, a total of 143 mg/L of alkaloid was produced in 8 days. In this way the alkaloid content of the cells was increased more than six times compared to that obtained in the standard MS medium. The steps leading to biotransformation of cholesterol into alkaloids were unaffected by phosphate. The shake flask data were successfully transferred to a bench scale 6-L stirred tank bioreactor in which the specific biosynthetic rate of alkaloid production was 110 mg/100 g dry cell weight per day, about 160 times higher than that of whole plant.