由质粒介导的豌豆根瘤菌(Rhizobium Leguminosarum)Nif D::Tn5向棕色固氮菌(Azotobacter vinelandii)的转移

通过助移质粒P~(PK2013)的推动,实现了携带豌豆根瘤菌(Rhizobium Legumi-nosarum)nif D::Tn5的质粒pRK2009由大肠杆菌(E.coli)向棕色固氮菌Az-otobacter vinelandii的转移,转移频率为每受体7×10~(-5),进一步将与pRK2509不相容的质粒pPHLJI转入这个转移接合子,筛选得到了两株相同的棕色固氮菌的突变菌株。由表型特征分析和活性互补实验证明该突变菌株在染色体中含有豌豆根瘤茵nif D::Tn5,是两不同种固氮微生物的固氮基因即豌豆根瘤菌nif D与棕色固氮菌nif D之间发生同源性重组的结果

TRANSFER OF PLASMID-BORNE RHIZOBIUM LEGUMINOSARUM NIF D::Tn5 TO AZOTOB ACTER VINELANDII

Plasmidp RK.2509 carrying R.leguminosarum nif D:: Tn5 was complemented in trans for conjugation by pRK2013 and transferred from Escherichia coli to Azotobacter vinelandii.The transfer frequency was 7×10-5 per recipient. Transconjugants were detected by conjugation of pPHLJI,which is incompatible with pPHLJI,into A. vinelandii strains containing the PRK2509 and simultaneous selection for kanamycin resistance (retention of Tn5) and ge-ntamyein resistance ( conferred by pPHLJI) .After screening and subculturi-ng the exconjagants a mutant strain, A.vinelandii WI, was obtained. Phen-otypic analysis and complementation assay of nitrogenase components demonstrated that A.vinelandii WI contained R.leguminosarum nif D::Tn5 in its genome and was yielded from homologous recombination between R.leguminosarum nif D and A.vinelandii nif D.