FIG. 4.

Phylogenetic tree showing the relationship of concatenated bchXYZ, bchLNB, and nifHDK genes from H. modesticaldum to those of other organisms containing these genes. Although not present in H. modesticaldum, alternative nitrogenase genes, anfHDK and vnfHDK, are also included to balance the tree. Organisms containing more than one set of genes used in the comparison appear multiple times in the tree. The following organisms were included in the analysis: Anabaena siamensis strain TISTR8012, Azospirillum brasilense, Azotobacter vinelandii, Bradyrhizobium sp. strain BTAi1, Bradyrhizobium sp. strain ORS278, Chlorobaculum tepidum, Chloroflexus aurantiacus, Clostridium acetobutylicum, Clostridium pasteurianum, Clostridium kluyveri, Desulfitobacterium hafniense strain Y51, Geobacter sulfurreducens, Heliobacterium modesticaldum, Jannaschia sp. strain CCS1, Klebsiella pneumoniae, Methanothermobacter thermoautotrophicus, Methanococcus maripaludis, Methanosarcina acetivorans strain C2A, Nostoc sp. strain PCC7120, Prosthecochloris aestuarii, Rhodobacter capsulatus, Rhodopseudomonas palustris, Roseiflexus castenholzii, Roseobacter denitrificans, Synechococcus elongatus strain PCC6301, and Synechocystis sp. strain PCC6803.