Mutants of Azospirillum brasilense altered in nitrogen fixation

Abstract Four revertants with Nif⁺ phenotype obtained from asm mutants of Azospirillum brasilense have been studied in respect to nitrogenase, enzymes of ammonia assimilation and utilization of poor nitrogen sources. The results indicate that nitrogenase expression is related to the activity of glutamate synthase and to the adenylylation of glutamine synthetase; moreover, nitrogen fixation seems correlated with the activities of the enzymes involved in the utilization of poor nitrogen sources.