PHYLOGENETIC POSITION OF AN OBLIGATELY CHEMOAUTOTROPHIC, MARINE HYDROGEN-OXIDIZING BACTERIUM, HYDROGENOVIBRIO-MARINUS, ON THE BASIS OF 16S RIBOSOMAL-RNA GENE-SEQUENCES AND 2 FORM-I RUBISCO GENE-SEQUENCES

Two form ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) gen es from the obligately autotrophic, marine hydrogen oxidizer Hydrogeno vibrio marinus were sequenced. The deduced amino acid sequences of bot h RuBisCOs revealed that they are similar to those of sulfur oxidizers (Thiobacillus) and a purple sulfur bacterium (Chromatium vinosum). Ac cording to the 16S rRNA gene sequences, H. marinus is also affiliated with these microorganisms, members of Thiomicrospira being the closest relatives. Sequence similarities of the 16S rRNA genes and of the RuB isCO genes among these gamma-Proteobacteria suggest a common autotroph ic ancestry. An ancestor of purple sulfur bacteria might be a common r oot of H. marinus and related sulfur oxidizers.