FIG. 1.

Unrooted distance matrix tree showing phylogenetic relationships based on 16S rDNA sequences of selected strains of proteobacteria. The topology of the phylogenetic tree was evaluated by bootstrap analysis with 1,000 replicates. Numbers indicate percentage bootstrap values of 1,000 replicates. USDA 4362 and USDA 4377 are phototrophic Bradyrhizobium species. Abbreviations where relevant and, in parentheses, accession numbers: strain S55 (D84187), R. palustris, Rhodopseudomonas palustris (D25312); B. japonicum, Bradyrhizobium japonicum (D11345); R. roseus, Rhodoplanes roseus (D25313); R. acidophila, Rhodopseudomonas acidophila (M34128); R. viridis, Rhodopseudomonas viridis (D25314); R. rubrum, Rhodospirillum rubrum (D30778); R. sphaeroides, Rhodobacter sphaeroides (D16425); R. capsulatus, Rhodobacter capsulatus (D16428); R. salexigenes, Rhodospirillum salexigenes (M59070); R. tennis, Rhodocyclus tennis (D16208); R. purpureus, Rhodocyclus purpureus (M34132); R. gelatinosus, Rhodocyclus gelatinosus (D16214); E. coli, Escherichia coli (V00348); R. etli, Rhizobium etli (U28916); R. leguminosarum, Rhizobium leguminosarum (U73208).