| An antifungal marine actinomycete Y12-26 was selected from marine microorganisms, which were obtained from the First Institute of Oceanography, State Oceanic Administration. The plant pathogenic antifungal compounds produced by Marine actinomycete Y12-26 was obtained, the structures of them were identificated, and the strain was identified.Through fermentation, solvent extrac, silica gel chromatography, thin layer chromatography, and high performance liquid chromatography and other ways, three antifungal compounds were isolated from the culture extract of strain Y12-26 by bioassay-guided fractionation, named Y12-26-A2a, Y12-26-A3a and Y12-26-A3b. The spectra data of UV, MS,1H-NMR,13C-NMR,2D NMR and others were used to identify these compounds. The molecular formula of the compound Y12-26-A2a was confirmed as C35H56O8, with a molecular weight of 604, as the same as the know compund bafilomycin D, which have a 16 carbons macrolide; The molecular formula of the compound Y12-26-A3a was confirmed as C35H58O9, with a molecular weight of 622, the structure is the same with the vacuolar type H+-ATPase inhibitor bafilomycin Al; The molecular formula of the compound Y12-26-A3b was confirmed as C35H58O8, with a molecular weight of 606, was identificated as a new compound which have a 16 carbons macrolide and a ether ring, similar to bafilomycins but just have one methoxy, and was named as bafilomycin K. The HPLC analysis method was established to analyze the three compounds in the process of fermentation and purification. Through the bioassay, the MIC of Y12-26-A3a and A3b against Pyricularia oryzae is 16 and 31μg/ml in vitro, but Y12-26-A2a only have weak antifungal active against Pyricularia oryzae in vitro.The marine actinomycete strain Y12-26 was identified by 16S rDNA gene sequence analysis and the study of morphological, physiological and biochemical characteristics. The results showed that the strain Y12-26 belonged to Streptomyces griseus. |
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