Identification of the nifJ gene coding for pyruvate: ferredoxin oxidoreductase in dinitrogen-fixing cyanobacteria.

A 329 bp DNA segment from both Anabaena variabilis and Anabaena PCC 7119 was amplified using the polymerase chain reaction (PCR). The sequences from the two cyanobacteria showed strong similarities to the corresponding part of the nifJ gene from Klebsiella pneumoniae and Enterobacter agglomerans. The present findings underline earlier results of enzymatic studies that heterocystous cyanobacteria possess a pyruvate:ferredoxin (flavodoxin) oxidoreductase (PFO). The nifJ gene segment could not be detected in the non-dinitrogen-fixing, unicellular cyanobacterium Anacystis nidulans which is also in accord with previous findings from enzyme assays.