EFFECT OF BIOREACTOR DESIGN AND AGITATOR SPEED ON THE GROWTH AND ALKALOID ACCUMULATION BY CULTURES OF CATHARANTHUS ROSEUS

Abstract An investigation was made into the effect of increasing maximum shear stress on cultures of Catharanthus roseus IDI grown in bioreactors both with and without baffles. The results indicated that cultures were adversely affected by a certain level of shear stress which resulted in lower biomass and alkaloid accumulation. The increased levels of shear stress present in the baffled bioreactor compared to those in the unbaffled bioreactor meant that the cultures grown within the former displayed these effects at a lower speed than the cultures within the latter, indicating that the average and maximum shear stress levels were cumulative. Cultures grown in the bioreactor with baffles also appeared to have an increased level of cell breakage with a concomitant release of alkaloid into the medium. The medium alkaloid kept overall alkaloid production levels higher than those achieved by cultures grown in the unbaffled bioreactor.