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【目的】从东乡野生稻(Oryza rufipogon)中分离和鉴定内生放线菌,对其进行抗菌活性筛选,并分析高抗菌活性菌株S123的次级代谢产物。【方法】采用S培养基对东乡野生稻内生放线菌进行分离、纯化,并构建16S r RNA基因序列系统发育进化树进行菌株鉴定。以琼脂扩散法和菌丝生长速率法进行抗菌活性筛选,同时设计简并引物检测菌株I型聚酮合酶(PKS-I)基因。对具广谱抗菌活性的菌株S123进行分批大量发酵,运用多种色谱方法对发酵产物进行分离、纯化,利用MS和NMR分析鉴定化合物的结构。【结果】从东乡野生稻中共分离到11株内生放线菌,分别属于链霉菌属(8株)和假诺卡氏属(3株)。其中有8株具有抗菌活性,8株呈现I型PKS阳性。从高抑菌活性菌株S123中分离到化合物Nigericin和17-O-demethylgeldanamycin,其中Nigericin对金黄色葡萄球菌、枯草芽孢杆菌及水稻纹枯病菌均有抑制活性。【结论】对东乡野生稻内生放线菌进行了分离、鉴定和抗菌活性筛选,并从中分到两种与I型PKS基因相关活性的化合物Nigericin和17-O-demethylgeldanamycin,为研究东乡野生稻内生放线菌的多样性和次级代谢产物的分离提供依据。
【Objective】 Endophytic actinomycetes were isolated and identified from Oryza rufipogon and screened for their antibacterial activities. Secondary metabolites of the highly active antibacterial strain S123 were analyzed. 【Method】 Endophytic actinomycetes from Dongxiang wild rice were isolated and purified by S medium and the phylogenetic tree of 16S rRNA gene was constructed for strain identification. The antibacterial activity was screened by agar diffusion method and mycelium growth rate method. At the same time, degenerate primers were designed to detect the type I polyketide synthase (PKS-I) gene. The strain S123 with broad-spectrum antibacterial activity was fermented in batches in batches. The fermentation products were isolated and purified by various chromatographic methods. The structures of the compounds were identified by MS and NMR. 【Result】 Eleven endophytic actinomycetes were isolated from Dongxiang wild rice, belonging to Streptomyces (8 strains) and Pseudonocardia (3 strains), respectively. Eight of them have antibacterial activity and eight show positive type I PKS. The compounds Nigericin and 17-O-demethylgeldanamycin were isolated from the highly active bacterium S123. Among them, Nigericin had inhibitory activity against Staphylococcus aureus, Bacillus subtilis and Rhizoctonia solani. 【Conclusion】 Endophytic actinomycetes in Dongxiang were isolated, identified and screened for their antibacterial activities. Two kinds of compounds, Nigericin and 17-O-demethylgeldanamycin, Endophytic actinomycetes diversity and secondary metabolites provide the basis for the separation.