Nitrogen FixationBiomassNitrogenaseSymbiosisAcetyleneRoot Nodules, PlantRhizobiumSinorhizobium melilotiRhizobiaceaeNitrogenNitrogen CycleNitrogen IsotopesLotusFixation, OcularGenes, BacterialAzotobacterMedicago sativaPlant RootsPlant Root NodulationPII Nitrogen Regulatory ProteinsFracture FixationRhizobium leguminosarumRhizobium etliCyanotheceBacterial ProteinsBradyrhizobiumCarbonLeghemoglobinCyanobacteriaAzotobacter vinelandiiKlebsiella pneumoniaeGene Expression Regulation, BacterialMedicago truncatulaCarbon CycleAnabaenaComplement Fixation TestsTissue FixationPhaseolusFabaceaeNitrogen CompoundsQuaternary Ammonium CompoundsMolecular Sequence DataGlutamate-Ammonia LigaseAmmoniaOxidoreductasesSoilDenitrificationPhotosynthesisNitrogen DioxidePseudomonas stutzeriMesorhizobiumBlood Urea NitrogenEcosystemBacteriaPlant ShootsNitratesMolybdoferredoxinMolybdenumBone ScrewsSeawaterBiofuelsSinorhizobiumPhylogenyDinitrogenase ReductaseSoil MicrobiologyGenes, ArchaealDNA, BacterialCarbon DioxidePoaceaePeasGluconacetobacterBase SequenceReactive Nitrogen SpeciesIsopteraMutationBone PlatesSoybeansOperonAzorhizobium caulinodansSesbaniaAzospirillum brasilenseAlnusAchromobacterPlant LeavesAnaerobiosisSequence Analysis, DNARhodobacter capsulatusHydrogenAerobiosisFertilizersExternal FixatorsViciaAlphaproteobacteriaFixativesPhosphorusOxidation-ReductionAmino Acid SequencePlantsCavesCulture Media