【摘要】 利用转座子Tn5随机插入突变法，从毛萼田菁茎瘤菌（Azorhizobiumcaulinodans）中筛选得到两株吸氢活性缺陷突变株（Hup-）R－49和R－309，其固氮酶活性也大大降低，约为野生型固氮酶活性的6％～8％。以带有Bradyrhizobiumjaponicum的5．9kb的hup基因的质粒pHR11为探针与A．caulinodansORS571和B.japonicum122DES（Hup＋）的总DNA进行分子杂交，放射自显影表明，A．coulinodans基因组含有与B.japonicum的hup基因同源的DNA片段，将携带B．japonicumhup基因的嵌合质粒pHR11与A.caulinodansHup-突变株进行体内遗传互补，接合转移子吸氢酶活性可以恢复至野生型的60％，同时固氮酶的活性亦有所提高。更多还原

【Abstract】 Two Hup- mutants (R-49 and R-309) from Azorhizobium caulinodans were obtained by Tn5 insertin mutation and their nitrogenase activities were significantly decreased to about 6%～8% of their wild type(Table 2). Southern hybridization indicated that A. caulinodans genomic DNA cntained hmological DNA fragment with B. japonicum hup genes (Fig. 2 ). When a plasmid (pHR11) containing 5. 9 kb hup genes of B. japonicum was transferred to A. caulinodans Hup- mutants, the hydrgenase activities of transconjugants were able to restore to about 60% of their wild type and the nitrogenase activities als increased(Table 2 ).更多还原