Cloning of a nitrogen fixation (nif) gene cluster of Azospirillum brasilense.

ABSTRACT

Homology was detected between the structural genes for the nitrogenase complex of K. pneumoniae (nifHDK genes) and the total DNA of several Azospirillum strains. Bacteriophage lambda gt 7-ara6 was used to construct a gene bank of A. brasilense strain 7000 DNA and a recombinant phage carrying a 6.7 kb Eco RI fragment, termed AbRI, was selected by hybridization with the K. pneumoniae nif probe. Using heteroduplex analysis the extent of the homology of the AbRI fragment and the K. pneumoniae nif genes was found to be approximately 5 kb. Proteins encoded by the AbRI fragment were examined after infection of E. coli minicells.