Introduction
Members of the order Aquificales represent a very deep phylogenetic branch within the 16S rRNA tree of the domain Bacteria. Within the order, members of the genus Aquifex have an upper temperature border of growth at 95°C and represent the bacteria with the highest growth temperatures known so far. Aquificales representatives are widespread and cosmopolitan, and they thrive mainly in volcanically or geothermally heated environments. Owing to their chemolithoautotrophic way of life, they are primary producers of bacterial biomass within high temperature ecosystems. In their energy-yielding reactions, they preferentially perform the “Knallgas” reaction, the oxidation of hydrogen and reduction of oxygen.
Phylogeny
By 16S rRNA gene sequence comparisons, it was shown that the Aquificales represent one of the deepest and earliest branching groups within the phylogenetic tree (Burggraf et al., 1992; Huber et al., 1992b; Fig. 1) along with the separate phylogenetic branch of the...
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Huber, R., Eder, W. (2006). Aquificales. In: Dworkin, M., Falkow, S., Rosenberg, E., Schleifer, KH., Stackebrandt, E. (eds) The Prokaryotes. Springer, New York, NY. https://doi.org/10.1007/0-387-30747-8_39
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