Objective: To initiate callus cell line of A. indica, develop suspension culture & study its growth and product formation kinetics under batch cultivation conditions in bioreactor.
Basic concepts & need of plant cell cultivation
Plants have provided us with food, fuel and fibers since prehistoric times. They have been inexhaustible source of a diverse array of chemicals such as flavors, fragrances, natural pigments, pesticides and pharmaceuticals. This seemingly unrelated collection of chemicals has been grouped together under a broad category of plant secondary metabolites, although many of them are known to be produced during active growth phase of the plant cells (DiCosmo and Misawa, 1995). The area which has received maximum attention from scientific community is the potential use of plant-derived compounds as a source of medicines, aromas and fragrances. Currently these compounds are being produced by cultivation of the whole plant followed by solvent extraction. This conventional process presents a number of disadvantages such as non-availability of the source plant throughout the year, risk of extinction of the plant species due to its mass collection and inconsistent product yield due to climatic variations. Hence, in vitro cultivation of plant cells in bioreactor is considered to be an attractive alternative and viable approach for the production of these compounds.
Bio-pesticide production from A. indica
Azadirachtin is presently being isolated by solvent extraction from the seed kernels of A. indica. The seed of this plant species are well known as a source of broad-spectrum biopesticides (azadirachtin and related limonoids) which can be used for crop protection in agriculture. However, distribution of neem tree is limited to arid zone of tropical regions due to its susceptibility to excessive frost. Azadirachtin production from seeds is also associated with several disadvantages e.g. the seeds are produced once in a year and a major fraction of seeds gets detoriated during storage. Seeds also have large variations with respect to azadirachtin content mainly due to diverse genotype and wider geographical distribution of neem trees. It is also observed that mature seeds get adulterated by fungus upon falling and may lead to deadly production of aflatoxin. Significant variability and availability of seed only in arid zones has triggered biotechnological production of biopesticides to cope up with its huge requirement. Plant cell cultivation technology can provide a viable alternative to whole plant cultivation for the production of secondary metabolites. The production of azadirachtin by cell cultures of A. indica has received significant attention from different investigators as being a promising alternative protocol.