Comparison of Various Strategies Designed to Optimize Indole Alkaloid Accumulation of a Cell Suspension Culture of Catharanthus roseus

The cell line CP-3 of Catharanthus roseus produces low levels of indole alkaloids during station­ary phase of growth, but increased levels when transferred to growth-limiting production media. Highest specific yields of alkaloids were usually achieved 8-15 days after transfer of the cells to the production medium. We attempted to reduce the time required for alkaloid production by altering preculture conditions, and by adding an elicitor preparation known to stimulate alkaloid accumulation in other cells. Reduction of 2,4-D in the last growth medium before transfer to production medium and a high initial inoculum load into the production medium resulted in rapid and greatest alkaloid accumulation (up to 2 mg ajmalicine/g dry mass or 40 mg/1 within 7 days). The addition of elicitor to the cell suspension stimulated high levels of tryptamine biosynthesis and accumulation under all culture conditions. Additionally, two cell lines derived from CP-3 cells and maintained on NAA/kinetin containing medium were selected for rapid growth in the absence of 2,4-D and were characterized with respect to their ajmalicine production. At a high inoculum load these cells produced up to 1.3 mg/g or 20 mg ajmalicine/1 when cultivated on the growth medium. The biotechnological utility of such cell lines is discussed.