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Metallosphaera sedula is an extremely thermoacidophilic archaeon (Topt 73°C, pHopt 2.0), originally isolated from a volcanic hot spring near Mt. Vesuvius, Italy. It belongs to the phylum Crenarchaeota and order Sulfolobales. M. sedula exhibits broad physiological diversity (‘metabolic goldmine’), as it can grow heterotrophically on peptides, autotrophically on reduced metals, sulfur or molecular hydrogen, and mixotrophically on both organic and inorganic energy sources. This archaeon can oxidize iron pyrite, chalcopyrite, ferrous sulfate or elemental sulfur to generate ATP, while fixing carbon dioxide into biomass through the novel 3-hydroxypropionate/4-hydroxybutyrate cycle. The M. sedula genome sequence, reported in 2006, revealed many details concerning the pathways and enzymes underlying its metabolic versatility. In addition to the unusual biology associated with M. sedula, it also is a biotechnologically important microorganism. The capacity to mobilize heavy metals from ores makes M. sedula a prime candidate for high temperature biomining or metal bioleaching, whereby microorganisms are utilized to breakdown the ore matrix, and thus release the metal of interest (e.g., gold, copper and uranium) into solution where it can be recovered. Metallosphaera species have now been isolated from hot, acidic biotopes world-wide, including in China and Yellowstone National Park (USA).