Cloning of pEA3, a large plasmid ofEnterobacter agglomerans containing nitrogenase structural genes

Summary A clone bank of an indigenous plasmid ofEnterobacter agglomerans containing structural nitrogen-fixation (nif) genes was established in a non-mobilisable, multicopy derivative of the cosmid vector pHC79. The restriction enzyme Bam HI was used to establish the clone bank and it was found that 96% of the clones contained inserts. The clones containingnif-genes were identified by Southern hybridisation usingKlebsiella pneumoniae nif DNA (KpnifHDKY) as the radioactive probe. Thenif-genes ofE. agglomerans showed extensive homology to those ofK. pneumoniae but the restriction enzyme fragment patterns of thenif-genes ofE. agglomerans were different. The plasmid bornenif-genes ofE. agglomerans are clustered as inK. pneumoniae.