Production of rosmarinic acid and biomass from adventitious root cultures of Ocimum basilicum by optimization of medium components in airlift bioreactors

Key message Optimum IBA concentration and MS medium salt strength are critically important determinants for production of rosmarinic acid and biomass in sweet basil adventitious root cultures through a balloon-type bubble bioreactor. Optimization of medium components for each species is critically important to produce valuable bioactive compounds at high yields in plant tissue and organ culture methods using bioreactor systems. Rosmarinic acid production in different in vitro culture methods of Ocimum basilicum L. (sweet basil) was evaluated in previous studies, however, to our knowledge, there was no available literature on adventitious root culture under bioreactor culture conditions. The aim of this study was to evaluate the effects of indole-3-butyric acid (IBA) concentrations (0.50, 1.0, 2.0 and 4.0 mg L-1) and Murashige and Skoog (MS) medium salt strengths (0.50, 0.75, 1.0 and 1.5) on biomass, accumulation of bioactive compounds (rosmarinic acid, total phenolic and flavonoid) in adventitious root cultures of sweet basil using a balloon-type bubble bioreactor. In addition to, antioxidant capacities (DPPH, ABTS and FRAP) and phenylalanine ammonia lyase activities (PAL) of adventitious roots were assessed. Also, the changes caused by these medium components in antioxidant enzymes activities (catalase, superoxide dismutase, peroxidase) and some stress parameters (malondialdehyde, hydrogen peroxide and proline) were investigated. The rosmarinic acid content of the adventitious roots was analyzed using UHPLC-HESI-MS/MS. Among the used medium components, 0.75 MS and 2 mg L-1 IBA were found to be the most appropriate quantities for biomass, PAL activities, accumulation of rosmarinic acid, phenolics and flavonoids, and activities of DPPH, ABTS and FRAP. The maximum accumulation of rosmarinic acid was determined as 20.98 +/- 1.38 mg g(-1) DW at 2 mg L-1 IBA which was 1.45, 1.19 and 4.02 times higher than 0.5, 1 and 4 mg L-1 IBA, respectively. Moreover, the content of rosmarinic acid at 0.75 MS was 1.94, 2.66 and 5.99-fold greater than 0.5, 1 and 1.5 MS, respectively. At these optimum conditions, the activities of antioxidant enzymes and the levels of stress parameters were generally determined to be lower. Overall, the results of our study make an important contribution to the mass production of rosmarinic acid in adventitious root cultures of sweet basil.