Abstract: In order to investigate antimicrobial activity of volatile substance of Epichloë sp.isolated from Festuca sinensis and its components,its fermentation metabolites were partitioned by volatile oil extractor and ethyl acetate in turn and evaluated for in vitro antimicrobial activity using agar diffusion method,cavity slide method and filter paper diffusion,respectively.The volatile substance was analyzed by means of solid-phase microextraction and gas chromatography-mass spectrometry (GC-MS).The results showed that volatile substance,ethyl acetate extract,water phase and fermentation liquid had different inhibitory effects against mycelial growth of fungi Bipolaris sorokiniana, Curvularia lunata and Aspergillus niger.The high concentrations of volatile substance inhibited significantly spore germination and germ tube length of the tested fungi compared to the low concentrations (P < 0.05).In addition,diameter of inhibition zone of bacteria Staphylococcus aureus and Escherichia coli were significantly increased by volatile substance treatment when compared with control (P < 0.05),with the inhibitory effect of the same volatile substance concentration on S. aureus being more than that of E. coli.Thirty-two compositions were identified from the volatile substance of Epichloë sp.endophyte by GC-MS analysis with high similarity.The main compositions were isosorbide (16.26%),propane,2-methoxy-2-methyl-(8.18%),dianhydromannitol (3.75%),2-propanone,1-hydroxy-(2.99%),acetic acid (1.22%),1-hexanol (1.20%),3-furaldehyde (0.92%),5-hydroxymethyldihydrofuran-2-one (0.86%),pentanoic acid,5-hydroxy-,2,4-di-t-butylphenyl esters (0.86%) and hexadecanoic acid,methyl ester (0.85%).Fermentation metabolites of Epichloë sp.isolated from F. sinensis had antibacterial and antifungal activities.

Key words: Festuca sinensis;Epichloë, sp.endophyte;volatile substance;antimicrobial activity;component