Several factors affecting hypericin production of Hypericum perforatum during adventitious root culture in airlift bioreactors

Hypericum perforatum L. is a traditional medicinal plant for the treatment of depression and wound healing, and hypericin is one of the main effective active substances. To optimize the culture system for producing hypericin in adventitious root, this study used balloon-type airlift bioreactors to investigate the effect of air volume, inoculation density, indole-3-butyric acid (IBA) concentration and methyl jasmonate (MeJA) concentration on hypericin content and productivity during adventitious root culture. Hypericin content and productivity were improved with increasing air volume, and 0.1 vvm (air volume/culture volume/min) was optimal for hypericin production. Inoculation density also had a great effect on hypericin accumulation. Hypericin content and productivity were favorable in an inoculation density of 5.0 g l⁻¹ and decreased when inoculation densities were lower or higher than 5.0 g l⁻¹. Furthermore, 1.25 mg l⁻¹ IBA enhanced hypericin content and productivity, but too low (≤0.50 mg l⁻¹) or too high (≥1.50 mg l⁻¹) IBA concentrations decreased hypericin accumulation. MeJA concentration significantly affected biomass accumulation and hypericin production. The biomass decreased and hypericin production increased with increasing MeJA concentration. Optimum hypericin content (1.61 mg g⁻¹ DW) and productivity (15.57 mg l⁻¹) were obtained at 350 μM MeJA. The hypericin content in bioreactor-grown adventitious roots was lower than in 3-year field-grown plants, but significantly higher than that in in vitro-grown plantlets and 1-year field-grown plants. Thus, the bioreactor culture of adventitious roots can realize rapid and mass production of hypericin in H. perforatum.