In this paper, the possibilities of productivity enhancement by an optimized control of the process conditions in the bioreactoris illustrated for the production of ajmalicine by Catharanthus rosesus in a two-stage batch process.During the second production phase, the productivity could be increased considerably by optimization of the glucose concentration in the medium and the aeration rate in the biotreactor.Both the dissolved oxygen concentration, and the concentration of other dissolved gaseous metabolites were controlling the productivity.Furthermore, the age of the inoculum appeared to be an essential factor.