Improved ajmalicine production and recovery from Catharanthus roseus suspensions with increased product removal rates

The potential of strategies for increasing secondary metabolite accumulation from plant cell cultures may still be partially limited by unfavorable conditions for biosynthesis (i.e. feedback inhibition, unfavorable equilibrium state)or product metabolism. In this paper, the rate of product removal was altered and used as a tool for probing the impact of these limiting conditions on product accumulation, using the production of ajmalicine and serpentine from Catharanthus roseus suspensions as a model system. The method for altering the in situ product removal rate was simple; Amberlite® XAD-7HP resin was enclosed in either a porous or less porous material, and experiments confirmed that the product removal rate was higher with resin enclosed in the porous Miracloth versus the less porous nylon. When resin was added to suspensions, higher ajmalicine production and recovery were associated with Miracloth-enclosed resin which had higher product removal rates. This simple experiment illustrated that further improvements in production and recovery were possible, indicating that conditions unfavorable for biosynthesis and/or product metabolism existed in cultures with nylon-enclosed resin. These results also suggest the importance of optimizing the product removal rate for improving the overall production and recovery of secondary metabolites from plant cell cultures