Characteristics of growth and tropane alkaloid synthesis in Atropa belladonna roots transformed by Agrobacterium rhizogenes

Abstract

Growth of Atropa belladonna hairy roots in shake flasks followed first-order kinetics. The specific growth rate was 0.28 d −1, corresponding to a doubling time of 60 h. In airlift reactors, first order kinetics were not observed due to nutrient limitation. Synthesis of tropane alkaloids was growth-associated; no atropine was released into the medium. Sugar concentrations were analyzed during hairy-root culture for calculation of atropine yield. Atropine yields from substrate were 1.4 mg g −1 in shake flasks and 0.46 mg g −1 in airlift reactors. Although levels of atropine in reactor-grown roots (0.37% dry weight) were higher than in shake-flask roots (0.25% dry weight), growth and substrate conversion were better in shake flasks. Activity in the flasks and bioreactors levelled off after 17–20 d, even though 20–22 g l −1 of sugar remained in the medium.