Isolation and identification of antimicrobial activity of endophytic fungi from Forsythia suspensa

Abstract:

[Objective] The aim of this study was to screen antimicrobial fungal strains and to investigate the main active constituent of endophytic fungi isolated from the medicinal plant Forsythia suspensa. [Methods] Fungal endophytes were isolated with routine tissue separation methods, and the antimicrobial activities of their fermentation products were detected by filter paper method against 3 bacterial strains. Metabolites of active fungal strains were analyzed by TLC, HPLC and HPLC-MS methods. The final active fungal strains were identified based on morphological characteristics and ITS sequence analysis. [Results] Among the 24 isolated strains whose inhibition zone diameters more than 10 mm, group of fermentation broth had 11 (45.8%), group of mycelia had 19 (79.2%). Active fungal strains were mainly isolated from fruit, and G5, G7, G10 showed stronger antibacterial activities. Phillyrin was detected from the intracellular products of isolate G10, which was identified as Colletotrichum gloeosporioides. [Conclusion] The endophytic fungi in F. suspensa were important source for the natural antimicrobial substances.