Effect of Subculture Cycle on Growth and Indole Alkaloid Production by Catharanthus roseus Hairy Root Cultures

Abstract

The effect of subculture cycles on Catharanthus roseus hairy root culture growth and indole alkaloid production was investigated by adapting the cultures to 2-, 3-, and 4-week cycles. Conductivity of the culture medium was measured every 2–3 days and the culture fresh weight determined using a conductivity-fresh weight correlation. Cultures were harvested in triplicate at 21, 28, and 35 days and analyzed for final biomass and indole alkaloid content. These experiments demonstrated that the subculture cycle could lead up to a 20% decrease in the doubling times of hairy root cultures when the subculture cycle is changed from 4- to 2-weeks. The 2-week subculture cycle yielded the fastest while the 4-week cycle yielded the slowest specific growth rates. Specific yields of tabersonine decreased from day 21 to 35 and was inversely correlated with biomass content. Total yields of lochnericine were highest in the 2-week cycle indicating a strong correlation to growth rate. Serpentine yields were lowest in the 2-week cycle and highest in the 4-week cycle, indicating inverse proportionality of serpentine accumulation to growth rate.