Regular articleHydrodynamic stress and limonoid production in Azadirachta indica cell culture

- Hydrodynamic stress (dissipation energy) was studied in Azadirachta indica cells.
- Reynolds stress, Kolmogorov scale length and particle size were analyzed.
- Low dissipation energy levels (shake flasks) favor the growth and viability cell.
- Intermediate dissipation energy (bioreactor 400 rpm) favor limonoids production.
- High dissipation energy (bioreactor 800 rpm) increases the reactive oxygen species.

Azadirachta indica cell culture has been used for the production of antifeedant limonoids in shake flasks and stirred-tank bioreactors (STBs). However, the hydrodynamic environment may lead to low product yield, affecting growth and cell viability. The aim of this paper was to determine the effect of three different hydrodynamic conditions, corresponding to shake flasks (120 rpm) and STB (400 and 800 rpm) on A. indica cell culture. Reynolds stress, turbulent eddy length, cell growth and viability, limonoid production, reactive oxygen species (ROS), and guaiacol peroxidase (GPX) response were analyzed. The most suitable treatment for biomass generation corresponded to shake flask (maximum of 15.69 ± 0.47 g DW/L), whereas limonoid production was favored at 400 rpm (8.37 ± 3.81 mg/g DW). Reynolds stress reached 62.21 ± 8.65 Pa at 800 rpm, and turbulent eddies were similar to the aggregate size. This affected cell growth and viability, while ROS concentration increased significantly (156.1 ± 104.2 FU/min) and GPX activity remained low, 0.04 ± 0.00 μmol TG/(mg protein min), suggesting hydrodynamic stress conditions. As far as we know, this study is the first that relates hydrodynamic stress conditions to limonoid production, cell growth and viability, ROS, and GPX in an A. indica cell culture.