Ajmalicine, Serpentine, and Catharanthine Accumulation in Catharanthus roseus Bioreactor Cultures

Abstract

A 141, stirred-tank bioreactor was used to investigate the effect of 7% glucose solutions on Catharanthus roseus suspension cultures. Measurement of oxygen uptake rate indicated that alkaloid accumulation occurred primarily during a 20-day transition period between growth-oriented metabolism and maintenance-oriented metabolism. Exposure of the cells to light during this period stimulated catharanthine accumulation and triggered a switch from ajmalicine accumulation to serpentine accumulation. In addition, it suppressed the secretion of both ajmalicine and serpentine; without light nearly 80% of the ajmalicine and serpentine was found in the medium, whereas with light less than 20% was secreted. Alkaloid accumulation was found to be adversely affected by increasing the volume of inoculum culture transferred to a given volume of fresh glucose solution, apparently due to the entry of 2,4-D with the inoculum.