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Phylogenetic position of the genus Hydrogenobacter
C Pitulle1, Y Yang, M Marchiani
1Department of Biochemical and Biophysical Sciences, University of Houston, Texas 77204-5934.
International Journal of Systematic Bacteriology
|October 1, 1994
Summary
Extremely thermophilic bacteria, Hydrogenobacter, are confirmed to be early branching Bacteria. Their phylogenetic position supports the theory of a thermophilic last common ancestor for all life.
Area of Science:
- Microbiology
- Evolutionary Biology
- Genomics
Background:
- The genus Hydrogenobacter comprises thermophilic, chemolithotrophic bacteria with unique metabolic pathways.
- Previous research suggested Hydrogenobacter's deep phylogenetic roots within the bacterial domain based on limited ribosomal DNA data.
Purpose of the Study:
- To precisely determine the phylogenetic placement of Hydrogenobacter species.
- To clarify the taxonomic relationships within the early-branching bacterial order Aquificales.
Main Methods:
- Sequencing of the complete 16S ribosomal DNA from Hydrogenobacter thermophilus TK-6, Calderobacterium hydrogenophilum Z-829, and Hydrogenobacter sp. strain T3.
- Phylogenetic analysis using the obtained 16S ribosomal DNA sequences.
Main Results:
- Confirmed that Hydrogenobacter thermophilus and Calderobacterium hydrogenophilum belong to the same genus, Hydrogenobacter.
- Validated the placement of the Aquifex-Hydrogenobacter complex within the early-branching bacterial order Aquificales.
- Established a single family, Aquificaceae, within the Aquificales order based on current phylogenetic understanding.
Conclusions:
- The deep evolutionary divergence of Aquificales supports the hypothesis that the last common ancestor of life was thermophilic.
- The metabolic characteristics of these ancient bacteria suggest chemoautotrophic carbon fixation by the last common ancestor.