中文摘要：

采用两种无氮培养基经平板划线法共分离筛选到澳洲野生稻（Oryza australiensis）45株内生固氮菌.利用全细胞蛋白电泳和插入序列指纹图谱对获得的内生固氮菌进行聚类分析,将其分为8个类群.其中类群Ⅰ有10株菌,类群Ⅱ为4株菌,类群Ⅲ、Ⅳ和Ⅴ均为3株菌,类群Ⅵ、Ⅶ和Ⅷ各有2株菌.对分离得到的内生固氮菌主要类群部分代表菌株的固氮活性进行了系统研究,结果表明,菌株在偏酸（pH值5.0）和偏碱（pH值9.0）的条件下均能保持较高的固氮酶活性,NaCl浓度在2%时达到最高固氮活性,NH4＋浓度达到7.5 mmol/L时,均无固氮酶活性,不同菌株所能利用的碳源不同.16S rDNA序列测定及系统发育分析显示：类群ⅠYH39与Burkholderia cepacia ATCC 25416T相似性为97%;类群Ⅱ为克雷白氏杆菌属（Klebsiella）,相似性为100%;类群Ⅲ为泛菌属（Pantoea）,相似性为99%;类群Ⅴ为草螺菌属（Herbaspirillum）,相似性为99%;类群Ⅶ为中华根瘤菌属（Sinorhizobium）,相似性为99%.本研究表明澳洲野生稻内生固氮菌资源具有遗传多样性.

英文摘要：

This research aimed to investigate the diversity of endophytic nitrogen-fixing bacteria in Oryza australiensis. Forty-five strains of endophytic diazotrophs were isolated from wild rice O. australiensis by using two selective nitrogen-free media, and analyzed for phylogenetic and nitrogen-fixing characteristics. The obtained endophytic nitrogen-fixing bacteria were divided into 8 clusters by using SDS-PAGE of whole-cell protein and IS-PCR fingerprinting. The strains were found to be able to maintain higher nitrogenase activity under acid（pH 5.0） or alkaline（pH 9.0） conditions. The highest nitrogen fixation activity occurred in 2% NaCl concentration. None of the strains showed nitrogenase activity at NH4＋ of 7.5 mmol/L. Among the 8 clusters, Cluster Ⅰ had 10 strains, followed by 4 strains of Cluster Ⅱ, 3 of Clusters Ⅲ, Ⅳ and Ⅴ, and 2 of Clusters Ⅵ, Ⅶ and Ⅷ. The homology was 97% between Cluster Ⅰ and Burkholderia cepacia ATCC 25416 T, 99% between Cluster Ⅴ and Herbaspirillum seropedicae DX35 T（KF357956.1）, 100% between Cluster Ⅱ and Klebsiella variicola CPB S30T（KF770986.1）, 99% between Cluster Ⅲ and Pantoea agglomerans PB17T（EU360112.1）, and 99% between Cluster Ⅶ and Sinorhizobium sp. T2T（FJ687994.1）. The results suggested that endophytic nitrogen-fixing bacteria of O. australiensis have genetic diversity, with different strains being able to use different carbon sources.