Abstract

Background: Plants are a source of a variety of secondary metabolites. Agrobacterium rhizogenes mediated hairy root cultures offer a great advantage for the production of these metabolites in large amounts in comparison to cell suspension cultures as they have the capability of fast growth along with genetic stability. In order to commercialise secondary metabolite production, the mass production of hairy root cultures is of paramount importance. Various conventional bioreactors, broadly classified as liquid phase and gas phase reactors, have been employed for this purpose which includes airlift, bubble column, stirred tank, trickle bed, nutrient mist, spray reactors and others.

Objective: This review discussed various aspects of hairy root culture in bioreactors.

Method: Peer-reviewed research literature was searched and screened for information about the evolution of designs of bioreactors used for hairy roots culture. Data was gathered after a keen search from research and review articles and is presented in this review paper.

Results: The major limitations of the conventional type bioreactor systems were high shear stress and oxygen deficiency, thus the demand for improved designs led to the evolution and designing of various types of bioreactor systems with low shear stress and better oxygen uptake in order to enhance yield productivity. Amidst these modifications in reactors, hybrid reactors, which are a combination of liquid phase and gas phase reactors, offer a very promising approach for commercialisation of secondary metabolite production using hairy root cultures.

Conclusion: Although many efforts have been done to obtain a bioreactor configuration for highest biomass possible, there are still chances of improvement to get the most suitable bioreactor that could provide high oxygen mass transfer, better growth characteristics, homogenous culture environment and minimum shear stress.

Keywords: Hairy roots, secondary metabolite, stirred tank reactor, airlift reactor, bubble column reactor, nutrient mist reactor.

Graphical Abstract