Aquifex pyrophilus

Aquifex pyrophilus is a rod-shaped bacterium with a length of 2 to 6 micrometers and a diameter of around half a micrometer. It is one of a handful of species in the Aquificae phylum, an unusual group of thermophilic bacteria that are thought to be some of the oldest species in the bacteria domain. Aquifex pyrophilus grows best in water between 85 and 95 °C, and can be found near underwater volcanoes or hot springs. It typically uses oxygen in its respiration, producing water as a byproduct, thus leading to the name 'Aquifex,' meaning 'water-maker.' However A. pyrophilus can even grow anaerobically by reducing nitrogen instead of oxygen. Members of the species tend to form large cell conglomerations, comprising up to 100 individual cells. It was discovered just north of Iceland. The genome of Aquifex aeolicus, a member of the same genus, has been successfully mapped. Comparison of this genome to other organisms showed that around 16% of its genes originated from the Archaea domain. It is assumed that A. pyrophilus also has this property.