Fig. 4

The nitrogenase activities of the nifB deletion mutants and their complementary strains in Mo-dependent nitrogen fixation conditions. a Nitrogenase activities of the P. polymyxa ΔnifB mutant and its complementary strains. b Nitrogenase activities of WT (P. sabinaeT27), deletion mutants ΔnifB1, ΔnifB3, ΔnifB4 and complementary strain ΔnifB1/nifB1. The nitrogenase activity was measured by acetylene reduction assay when bacterial cells were grown anaerobically in nitrogen limited medium containing Mo. Error bars indicate the SD observed from at least three independent experiments