“Fungal elicitors combined with a sucrose feed significantly enhance triterpene production of a Salvia fruticosa cell suspension”

Abstract

Oleanolic (OA) and ursolic acid (UA) are plant secondary metabolites with diverse pharmacological properties. To reach reasonable productivities with plant cell suspension cultures, elicitation is a widely used strategy. Within the presented work, the effects of different elicitors on growth and production of OA and UA in a Salvia fruticosa cell suspension culture were examined. Beside commonly used elicitors like jasmonic acid (JA) and yeast extract, the influence of medium filtrates of the endophytic fungi Aspergillus niger and Trichoderma virens was investigated. The best eliciting effects were achieved with JA and fungal medium filtrates. Both increased the triterpene content by approximately 70 %. Since JA showed significant growth inhibition, the volumetric triterpene yield did not increase. But, adding fungal filtrates increased the volumetric triterpene yield by approximately 70 % to 32.6 mg_OA l⁻¹ and 65.9 mg_UA l⁻¹ for T. virens compared to the control with 19.4 mg_OA l⁻¹ and 33.3 mg_UA l⁻¹. An elicitation strategy combining fungal medium filtrate of T. virens with sucrose feeding significantly enhanced cell dry weight concentration to 22.2 g l⁻¹ as well as triterpene content by approximately 140 %. In total, this led to an approximately 500 % increase of volumetric triterpene yield referring to the control with final values of 112.9 mg_OA l⁻¹ and 210.4 mg_UA l⁻¹. Despite the doubled cultivation duration, productivities of 6.7 mg_OA l⁻¹ day⁻¹ and 12.4 mg_UA l⁻¹ day⁻¹ were reached. These results demonstrate methods by which increased productivities of triterpenes can be achieved to attain yields competing with intact plants.