Bioprocess design to scale-up adventitious root biomass and associated key flavouring N-alkylamides from Spilanthes paniculata Wall. ex DC. in a modified photobioreactor

• A novel photo-bioreactor configuration is developed for large-scale plant root biomass production. • The developed photo-bioreactor configuration yielded higher root biomass in shorter duration than the available optimized methods. • Kinetic modelling is also performed using logistic, Ludeking-Piret, and modified Gompertz equations in this modified photo-bioreactor for further provisions of scale-up of biomass and metabolite production. • The optimized kinetic models are implemented in this study to scale up the adventitious root biomass as well as the two key medicinal N-alkylamides- Spilanthol and DTAI. • The study outcomes would be an ideal tool for pilot or commercial level production of biomass as well as metabolites. A novel photo-bioreactor configuration is developed for root biomass production from Spilanthes paniculata. The plant is widely used in food industry for food flavouring and food preservation, and is a rich source of N-alkylamides that has uses in cosmetics and medicines too. Further, roots are genetically and phytochemically very stable over successive generations but being a filamentous plant organ, it requires special attention during scaling-up process. Therefore, this study is aimed to provide optimized culture parameters for large-scale production of adventitious root biomass and N-alkylamides in modified stirred tank photobioreactor (MSTR). Bioreactor parameters, like inoculum density (6.0 g/L, FW), aeration (0.5 vvm) and agitation (150 rpm) were successfully optimized in MSTR. It yielded highest roots biomass of 73.34 ± 2.20 g/L (FW) and 10.01 ± 0.29 g/L (DW) on ½ MS (only major salts reduced to half strength) liquid basal medium with 5 % sucrose. It also resulted in increased production of two prominent N-alkylamides, spilanthol (720.44 ± 27.45 µg/L) and DTAI (3608.03 ± ± 92.81 µg/L). Additionally, logistic equation was employed for kinetic modelling of root biomass growth in MSTR. Metabolite productivity data obtained from MSTR was fitted to Ludeking-Piret and modified Gompertz equation, which showed partially growth-associated phenomenon for metabolite production. Maximum metabolite concentration was 963.76 µg/L for spilanthol and 3914.71 µg/L for DTAI. Outcomes of this study may overcome limitations of plant biomass availability due to seasonal and geographical restrictions . This study is a pioneering step towards fulfilling a wide gap between laboratory and industrial-scale plant biomass and metabolites production.