Zou X, Feng X L, Chen W X, Li F D
College of Biological Sciences, China Agricultural University, Beijing, People's Republic of China.
Plasmid. 1998 Sep;40(2):158-63. doi: 10.1006/plas.1998.1356.
Rhizobium sp. strain S25 was isolated from the nodule on Tephrosia candida in Hainan Province, China. The strain showed high stress tolerance. The plasmid profile of strain S25, examined by the Eckhardt procedure, indicated that the strain harbors only one plasmid with an estimated size of 150 kb. The plasmid was shown to carry nod and nif genes by hybridization with probes of nodABC and nifHDK genes. Plasmid curing was carried out using the Bacillus subtilis sacB to generate derivatives of strain S25. In comparison with the parent strain S25, the cured derivative lost its ability to nodulate the host plant. Loss of the plasmid reduced significantly the strain's tolerance to acid, nitrous, and multiple antibiotics. The properties of the cured strain also indicated that the plasmid was involved in carbon and nitrogen metabolism. Reintroduction of the plasmid from S25 in the cured derivative restored its original biological phenotypes.
根瘤菌属菌株S25是从中国海南省白花灰叶豆的根瘤中分离得到的。该菌株表现出较高的胁迫耐受性。通过埃克哈特方法检测，菌株S25的质粒图谱表明该菌株仅含有一个估计大小为150 kb的质粒。通过与nodABC和nifHDK基因探针杂交，表明该质粒携带结瘤基因和固氮基因。使用枯草芽孢杆菌sacB进行质粒消除以产生菌株S25的衍生物。与亲本菌株S25相比，消除质粒的衍生物失去了对宿主植物结瘤的能力。质粒的丢失显著降低了该菌株对酸、亚硝酸盐和多种抗生素的耐受性。消除质粒菌株的特性还表明该质粒参与了碳和氮代谢。将S25的质粒重新导入消除质粒的衍生物中恢复了其原始生物学表型。
