高秆野生稻内生固氮细菌多样性

高秆野生稻(Oryza alta)是一种重要的种质资源, 其组织内也蕴藏着非常宝贵的功能微生物资源。本实验采用无氮培养基, 从高秆野生稻中分离到43株内生固氮菌, 结合乙炔还原法测定其固氮酶活性。经固氮酶基因(nifH)的PCR扩增检测, 43株内生固氮菌代表菌株均能扩增出固氮酶基因片段。利用IS-PCR DNA指纹图谱和SDS-PAGE全细胞蛋白电泳图谱将获得的菌株聚类为6个类群(I、II、III、IV、V、VI)。对各个类群的代表菌株(ZF3, ZF8, ZF13, ZF15, ZF24, ZF43)进行16S rRNA基因序列测定, 结果表明, 类群I属于土生拉乌尔菌(Raoultella terrigena), 类群II属于类肺炎克雷伯氏菌类肺炎亚种(Klebsiella quasipnmoniae subsp. quasipneumoniae), 类群III属于越南伯克氏菌(Burkholderia vietnamiensis), 类群IV的菌株代表肠秆菌属的一个类群(Enterobacter sp.), 类群V的菌株属于门多萨假单胞菌(Pseudomonas mendocina), 类群VI归属于固氮植物菌(Phytobacter diazotrophicus)。Biolog聚类结果与IS-PCR指纹图谱类型及SDS-PAGE全细胞蛋白聚类结果一致。Biolog板测定结果显示, 来自不同类群的代表菌株对碳源的利用差异显著, 说明野生稻内多样的内生固氮菌从环境中获取碳源和氮素的适应能力较强。

Diversity of endophytic diazotrophs isolated from Oryza alta

Forty-three strains of endophytic nitrogen-fixing bacteria were obtained from wild rice Oryza alta, and grown on nitrogen-free medium. Their potential nitrogen-fixing ability was determined with the acetylene reduction method and a PCR amplification of the nifH gene fragment. The obtained isolates were grouped into six groups (I, II, III, IV, V, VI) based on their DNA patterns of IS-PCR and protein patterns of SDS-PAGE. The 16S rRNA gene sequence analysis identified representative strains, suggesting that group I belonged to Raoultella terrigena, group II to Klebsiella quasipneumoniae subsp. quasipneumoniae, group III to Burkholderia vietnamiensis, group IV to genus Enterobacter, group V to Pseudomonas mendocina, and group VI to Phytobacter diazotrophicus. A Biolog plate test showed strains from differing groups had significant differences in carbon source utilization, often clustering consistently within IS-PCR and SDS-PAGE patterns. The diversity of endophytic nitrogen-fixing bacteria in wild rice indicates that endophytic bacteria is strongly adaptable in obtaining both carbon and nitrogen from varying environments.