Isolation of Pure Species of Wild Boletaceae and Optimization of Inducer for Triterpenoid Synthesis in Liquid Culture

Objective: To obtain artificial pure strain of porcini and improve the ability of liquid culture mycelium and production of triterpenoid. Methods: The fresh wild Boletaceae fruit bodies from Yunnan were used for the study, and the parent pure strain was isolated and identified by tissue isolation method; Ca²⁺, linoleic acid, and mushroom aqueous extract were used as inducing agents to study their effects on the content of triterpenoids in liquid mycelium. Results: A pure strain of NG-3 was obtained by multiple purifications and identified by rDNA-ITS molecular biology as Phlebopus portentosus; the mycelium of NG-3 was observed by SEM, and the lock-like joint morphology mycelium with the ability of fruiting appeared at 8-16 d of cultivation. Three inducers were optimized by response surface methodology. The results showed that the concentration of Ca²⁺ was 12 mmol/L, the amount of linoleic acid was 4%, and the concentration of mushroom aqueous extract was 155 mg/100 mL, at which time the triterpene content was 6.77 mg/g, which was 76% higher than the triterpene content without inducer. Conclusion: The combination of three inducers can promote the synthesis of triterpenoids and increase their content, which can provide technical parameters to solve the shortage of wild resources and realize the industrialization of functional products of Boletaceae.