Based on 16S ribosomal ribonucleic acid (rRNA) genes sequence comparisons, the order Aquificales represents a very deep phylogenetic branch within the bacterial domain. Some Aquificales relatives have an upper temperature limit of growth at 95°C. Together with members of the order Thermotogales, they represent bacteria with the highest growth temperatures known so far. However, unlike Thermotogales, most of the members of the order Aquificales are aerobic or anaerobic lithoautotrophs, using energy of molecular hydrogen, or of reduced sulfur compounds to support their growth.
Keywords: Aquificales; bacteria; lithoautotrophs; thermophiles; evolution








