Scale-up production of Vigna caracalla meristematic nodules in a pneumatically agitated, air-lift like bottle bioreactor system

In the present study, the large-scale production of meristematic nodules of Vigna caracalla L. Verdc. was achieved in a pneumatically agitated bottle bioreactor system. This species is valued both as an ornamental climbing plant, owing to its distinctive coiled flowers and strong fragrance, and as a potential model for biotechnological applications, thereby justifying efforts to develop efficient propagation systems. Leaf and stem explants from 14-day-old seedlings were cultured on Murashige and Skoog (MS) medium with different plant growth regulators (PGRs). 14-day-old leaf-derived calli were transferred to 250 mL Erlenmeyer flasks with 50 mL of diverse liquid media to optimize nodule production. According to the results for fresh weight (FW), specific growth rate (SGR), doubling time (DT), and fresh growth index (FGI), the SMN-3 (SMN: secondary meristematic nodule) medium [½ MSB5 (MS salts+B5 vitamins) +4.0 mg/L 6-benzylaminopurine (BAP)+100 mg/L ascorbic acid (AA)+100 mg/L glutamine+15 mg/L sucrose] provided the best response. Finally, large-scale production of meristematic nodules was optimized in a 2 L air-lift-like bottle bioreactor. 9.6 g/L inoculum in 1.6 L SMN-3 maximized FW, SGR, FGI, and biomass growth. These findings highlight a significant advancement in meristematic nodule production in Vigna caracalla, showcasing the potential of a cost-effective, air-lift bioreactor system for large-scale applications.