Endophytic fungus EF-WCH-51 from Yulania denudata ‘Hailuo’: strain identification and determination of active component against Colletotrichum orbiculare

Abstract:

[Background] The endophytic fungi of medicinal plants have good biocontrol potential because the secondary metabolites they produced have a variety of antimicrobial activities. [Objective] To identify an endophytic fungus EF-WCH-51 with inhibitory activity against Colletotrichum orbiculare (a pathogen causing anthracnose of melons) from Yulania denudata ‘Hailuo’ and determine its main antifungal component. [Methods] Strain EF-WCH-51 was identified based on morphological characteristics and molecular sequences. The growth rate method was employed to determine the antifungal activity of EF-WCH-51, and semi-preparative HPLC and HPLC-MS/MS to identify the active component. [Results] Strain EF-WCH-51 was identified as Lecanicillium aphanocladii. The crude extract of its fermentation broth had a strong inhibitory effect on the mycelial growth of C.orbiculare, with EC₅₀ of 0.086 2 mg/mL. The inhibitory rate of the bioactive compound A (0.085 0 mg/mL) against C.orbiculare was 76.08%. The compound was identified as oosporein by data comparison with MS, MS/MS databases and related literature. [Conclusion] L. aphanocladii, with oosporein as the main antifungal active component, had good inhibitory activity against C. orbiculare, demonstrating the potential as a biocontrol strain against C. orbiculare.