【摘要】 对从北京郊区玉米根际分离到的巴西固氮螺菌(Azospirillum brasilense)Yu62的质粒进行了分离和检测,发现检测方法不同,得到的质粒数目也不同,用 Kado 法只发现一个大质粒,以 pABm 1表示,其分子量约为120 Md;而用改良的 Eckhardt 方法,则发现有5个大质粒,分别以 pABm 1、pABm 2、pABm 3、pABm 4和 pABm 5表示,它们的分子量分别约为120 Md、330 Md、360 Md、480 Md 和900 Md,都是巨型质粒,用多种方法检测均未发现小质粒。应用生物素标记的核酸杂交技术制备了 Biotin-nifHDK 探针,并对 Yu62菌株的质粒及染色体片段进行了 Southern 印迹杂交和斑点杂交,杂交结果表明 nifHDK 基因定位于染色体上。更多还原

【Abstract】 Azospirillum brasilense Yu62 is an asso-ciative nitrogen fixation bacteria which wasisolated from the rhizosphere of maize grownin the suburb field of Beijing.Five plasmidshave been found in Yu62 and the molecularweight of them is 120,330,360,480,and 900Md,respecitively.Various procedures for iso-lating plasmid gave out different number ofplasmid:with Kado’s Method,only 120 Mdplasmid could be detected;with the improve-ment of Eckhardt’s method,all five plasmidscould be identificated.In addition,this straindoes not harbor small plasmid.Analysis with the Biotion-nifHDK probeby Southern hybridization and Dot hybridi-zation showed that the nifHDK gene of thisstrain was not located on the plasmids buton the chromosome.更多还原