Production of the Biopesticide Azadirachtin by Hairy Root Cultivation of Azadirachta indica in Liquid-Phase Bioreactors
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Batch cultivation of Azadirachta indica hairy roots was carried out in different liquid-phase bioreactor configurations (stirred-tank, bubble column, bubble column with polypropylene basket, and polyurethane foam disc as root supports) to investigate possible scale-up of the A. indica hairy root culture for in vitro production of the biopesticide azadirachtin. The hairy roots failed to grow in the conventional bioreactor designs (stirred tank and bubble column). However, modified bubble column reactor (with polyurethane foam as root support) configuration facilitated high-density culture of A. indica hairy roots with a biomass production of 9.2 g l−1dry weight and azadirachtin yield of 3.2 mg g−1 leading to a volumetric productivity of azadirachtin as 1.14 mg l−1 day−1. The antifeedant activity in the hairy roots was also evaluated by no choice feeding tests with known concentrations of the hairy root powder and its solvent extract separately on the desert locust Schistocerca gregaria. The hairy root powder and its solvent extract demonstrated a high level of antifeedant activity (with an antifeedant index of 97 % at a concentration of 2 % w/v and 83 % at a concentration of 0.05 % (w/v), respectively, in ethanol).
KeywordsAzadirachtin Hairy roots Azadirachta indica Bubble column reactor Polyurethane foam Antifeedant index
The authors are thankful to Dr. Subramanyam, Principal Scientist, Division of Entomology, Indian Institute of Agricultural Research, Delhi, for his assistance in the antifeedant assay. The financial support by the Department of Biotechnology, Ministry of Science and Technology, New Delhi (India) for the execution of the above research is gratefully acknowledged.
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