AnabaenaAphanizomenonCyanobacteriaAnabaena variabilisAnabaena flos-aquaeNitrogen FixationPhylogenyMolecular Sequence DataNitrogenaseAnabaena cylindricaAcetyleneRNA, Ribosomal, 16SBacterial ProteinsDNA, RibosomalPhycocyaninDNA, BacterialSequence Analysis, DNAFlavodoxinGenes, BacterialNostocNitrogenFerredoxin-NADP ReductaseGene Expression Regulation, Bacterial