The Screening Of Streptomyces Sp.SN-194 And Its Secondary Metabolites Against Pathogenic Fungi

20 strains of Actinomycetes which had been preserved in the laboratory of the pest and environmental safety in Shenyang Agricultural Uinversity were fermented, in this paper. The metabolite crude extracts were obtained by using the method of macroporous adsorption resin and solid phase extraction from 20 strains of these Actinomyces. The inhibitory effects and mechanisms of 20 metabolite crude extracts to Botrytis cinerea, Phytopthora capsici Leonian, Magnaporthe oryzae, Fusarium graminearum, Exserohilum turcicum, Bipolaris sorokiniana, Fusarium moniliforme and Sunflower S. scleroiorum were studied with the mycelial growth rate method. Finally SN-194 had been selected.Extracted DNA from SN-194, then amplified and sequenced gene of 16S rRNA. According to the result to construct evolutionary tree. SN-194 strain was large-scale cultured in liquid fermentation, and Compounds were purified by silica gel column chromatography, Sephadex LH-20 chromatography and semi-preparative high-performance liquid chromatography methods from the metabolic products of it.Their chemical structures were elucidated by spectroscopic technologies including nuclear magnetic resonance (NMR) and MS. The inhibitive activity of compounds against Botrytis cinerea, Phytophthora capsici and Sunflower S. scleroiorum were tested by mycelium growth rate method.The main test results were as follows:The activity against Phytogathogenic Fungi of SN-194 in the 20 strains of Actinomycetes was relatively strong.The extract of the secondary metabolites has a good inhibitory effect on Botrytis cinerea, Phytophthora capsici and Sunflower S. scleroiorum which extracted from SN-194. The identification of Actinomycetes SN-194 by the method of 16S rRNA made the clue that the strains has belongs to Streptomyces.Four compounds A, B, C and D were isolated from solid extract of SN-194.The compounds were identified as Oxaloterpin C, Oxaloterpin D, Oxaloterpin E and Viguiepinol, which are diterpenoids.The EC50 for inhibitive activity of compound A against Botrytis cinerea, Phytophthora capsici and Sunflower S. scleroiorum were 80.08,43.43 and 55.31.The EC50 for inhibitive activity of compound B against Botrytis cinerea, Phytophthora capsici and Sunflower S. scleroiorum were 24.71,21.44 and 114.00.The EC50 for inhibitive activity of compound C against Botrytis cinerea, Phytophthora capsici and Sunflower S. scleroiorum were 48.65,43.87 and 32.48.The EC50 for inhibitive activity of compound D against Botrytis cinerea. Phytophthora capsici and Sunflower S. scleroiorum were 25.79.46.92 and 122.73.The inhibitive activity of compound B against Botrytis cinerea and Phytophthora capsici is better than the others. The inhibitive activity of compound C against Sunflower S. scleroiorum is better than the others.