Proteases from Cynara cardunculus L. are used in cheese-making. The growth of C. cardunculus cell suspension culture and the production of proteases and phenols were studied in sucrose-limited chemostat cultures at two dilution rates. Biomass yields and biomass and protease productivities in chemostat cultures were compared with those in batch cultures. C. cardunculus cells showed a high ability to adapt to chemostat conditions. Phenolic production was not observed in the steady-state cultures of C. cardunculus cell cultures in contrast to batch cultures. Protease production was linked to the exponential growth phase and was higher and more stable in sucrose-limited chemostats than in batch culture.

In Catharanthus roseus cell cultures the time courses of four enzyme activities, tryptophan decarboxylase (TDC), strictosidine synthase (SSS), geraniol-10-hydroxylase (G10H) and anthranilate synthase (AS), and alkaloid accumulation were compared under two different culture conditions (low-inoculum density and high-inoculum density on induction medium) and a control on growth medium. In growth medium a transient increase in TDC activity was first observed after which G10H reached its maximum activity; only tryptamine accumulated, no ajmalicine could be detected. Apparently, a concerted induction of enzyme activities is required for ajmalicine formation. Cells inoculated in induction medium showed such a concerted induction of AS, TDC and G10H activities. After 30 days the low-density culture had accumulated six times more ajmalicine (in μmoles/g) than the high-density culture. Thus, increase in biomass concentration (high-density cultures) did not enhance the total alkaloid production. The major differences observed in enzyme levels between high-and low-density cultures were in the AS and TDC activities, which were two to three times higher in the low-density culture, indicating that there is a positive correlation between ajmalicine formation and AS and TDC activities.