The effect of the aggregate size on the production of ajmalicine and tryptamine in Catharanthus roseus suspension culture

A suspension culture of Catharanthus roseus grown in shake flasks was placed in a bioreactor containing production medium. After 6, 9, and 12 days, samples were taken and sieved to obtain six fractions of different aggregate sizes. The consecutive analysis for their contents of ajmalicine, tryptamine, internal sugars, and starch revealed that small aggregates (<150 mu m) produced more than twice as much ajmalicine as the biggest aggregates (>250 mu m) and reached 0.45 mu mol g(-1) dry cell mass by 12 days of culturing. The content of ajmalicine in the biggest aggregates (>250 mu m) decreases with culture age whereas the contents of tryptamine in those aggregates increases. Responsible for this distinct ajmalicine production among the different aggregate sizes is the tendency to form internal stored carbohydrates. Figures based on the active biomass show that all aggregates synthesize about the same amount of ajmalicine; production increases with the age of the culture. Ajmalicine production seems to be hindered only in the case of the aggregates larger than 250 mu m in diameter. (C) 1999 Elsevier Science Inc.