fixA, B and C genes are essential for symbiotic and free-living, microaerobic nitrogen fixation

Abstract

Site-specific mutations were contructed within Bradyrhizobium japonicum fixA, B and C regions that had previously been identified by interspecies hybridization [(1985) Mol.Gen.Genet. 199, 315-322]. The corresponding mutants were not only Fix- in otherwise fully developed soybean root nodules but also Nif- in free-living microaerobic culture. Specific fixA, B and C probes hybridized to DNA of the aerobic diazotroph, Azotobacter vinelandii. We hypothesize, therefore, that fixA, B and C genes are of general importance for aerobic/microaerobic nitrogen fixation. © 1986.