| The aim of this study was to investigate on the strain identification and screening of culture medium as well as purification and structural elucidation of secondary metabolites from a fungal strain ZME, isolated from soil of Sichuan Province, China.Firstly, strain ZME was identified according to its morphology and ITS sequences. ITS1-5.8S-ITS2rDNA of strain ZME was PCR amplification using primers ITS1and ITS4, which has100%similarity with ITS sequence of Beauveria felina EN135. Strain ZME and Beauveria feline located at the same branch location with the nearest evolutionary relationship of99%bootstrap value by constructing the phylogenetic trees with Rhizopus oryzae as outgroup, which has the same result with NCBI Blast result. Based on ITS analysis in combination with the morphology of strain ZME on PDA medium and hypha observation by optical microscopy, strain ZME belongs to Beauveria feline (Phyla:Ascomycota; Class: Sordariomycetes; Order:Hypocreales; Genus:Beauveria).Three culture mediums were used to culture of strain ZME. Differences of TLC spots and LC-MS chromatogram, as well as new bioactive metabolite was discovered using PDB medium, which is the first report about antibacterial activity of Beauveria feline, while there are no antibacterial metabolites using other two mediums. The antibacterial activity reached maximum level6days cultivation after inoculum.Antibacterial metabiolite and five other compounds, according to bioactivity-based purification, were isolated from Beauveria feline by silica gel column chromatography and semi-preparative HPLC. On the basis of spectroscopic analysis including ESI-MS,1D-and2D-NMR, these six compounds were Isaridin B, Isaridin A, Reseocardin, Roseotoxin B, Destruxin B and ergosterol. Compounds Isaridin B, Isaridin A, Reseocardin, Roseotoxin B and Destruxin B are cyclodepsipeptides, among which reseocardin, to our knowledge, is the first report about its antibacterial activity. |
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