Study on the Inhibitive Effect of 3 Antimicrobial Agents on Endophytic Fungi Aspergillus niger in Huperzia serrata (Thunb) Trev

[Objective] To explore the inhibitory effect of three antimicrobial agents against Aspergillus niger, a dominant endophytic fungus in Huperzia serrata (Thunb) Trev. [Method] Aspergillus niger was isolated from Huperzia serrata (Thunb) Trev by plate coating method, and the inhibitive effect of three antimicrobial agents against Aspergillus niger was obtained by mycelial growth rate method. Effect of three antimicrobial agents on H. serrata was conducted by inoculating stem segments on MS media with antimicrobial agents or by inoculating stem segments which were soaked in the minimum concentrations of antimicrobial agents for one or two days on MS media without antimicrobial agents. [Result] The minimal inhibitory concentrations of amphotericin B, sodium benzoate and cinnamaldehyde for Aspergillus niger were 512.000 00 mg/L, 4.00 g/L and 0.500 000 mg/L, respectively. Their EC50 were respectively 1.910 00, 150.000 00 and 0.120 00 mg/L, and their EC90 were 88.22, 730.00 and 0.330 00 mg/L respectively. Amphotericin B was the optimum antimicrobial agent for Aspergillus niger in Huperzia serrata (Thunb) Trev. [Conclusion] The minimum inhibitory concentrations of three antimicrobial agents for Aspergillus niger were obtained, which provided experimental basis for tissue culture of Huperzia serrata (Thunb) Trev.