Sparge gas composition affects biomass and ajmalicine production from immobilized cell cultures of Catharanthus roseus

Sparge gas composition significantly altered growth and ajmalicine production. Low and high O2 concentrations (10, 90, 95% O2) were either inhibitory or toxic to growth and ajmalicine production. The effects of CO2 depended on O2 concentration. At lower O2 concentrations (21% O2), increasing the CO2 concentration decreased both growth and specific ajmalicine production. At higher O2 concentrations (78.4% O2), increasing the CO2 concentration decreased growth while specific ajmalicine production was not affected. In these studies, extracellular ajmalicine concentration was maximized with a gas mixture of 50% O2 + 0.03% CO2.