Ferroplasma is a genus of Archaea that belong to the family Ferroplasmaceae. Members of the Ferroplasma are typically acidophillic, pleomorphic, irregularly shaped cocci. The archaean family Ferroplasmaceae was first described in the early 2000s. To date very few species of Ferroplasma have been isolated and characterized. Isolated species include Ferroplasma acidiphilum, Ferroplasma acidarmanus, and Ferroplasma thermophilum. A fourth isolate Ferroplasma cupricumulans was later determined to belong to a separate genus. All known Ferroplasma sp. are iron-oxidizers. Cell characteristics and Physiology Ferroplasma cells are pleomorphic and lack a cell-wall. All known members of the genera are acidophiles that thrive in environments where pH ranges from 0.0 to 2.0. They are also mesophilic to moderately thermophilic with optimal temperatures ranging from 35-55 °C. Tetraether-based lipids are an important part of the Ferroplasma cellular membrane and allow cells to maintain a pH gradient. A study of F. acidarmanus found that cytoplasmic pH was maintained ~5.6 while the environmental pH ranged from ~0-1.2. Variations in the tetraether lipids of the family Ferroplasmaceae are used for chemotaxonomic identification at the genus and species level because many members possess identical 16S rRNA sequences. Members of the genus Ferroplasma are chemomixotrophs that can oxidize ferrous iron to acquire energy, but despite evidence of carbon fixation, lab cultures often require an organic carbon source such as yeast extract for growth. In the absence of iron, some lab-grown strains have been capable of chemoorganotrophic growth. Ecological Importance Iron is the fourth most abundant mineral in earth's crust. As iron-oxidizers Ferroplasma sp. participate in the biogeochemical of iron. Ferroplasma sp. are often identified at acid mine drainage (AMD) sites. When ferrous iron (Fe2+) is oxidized to ferric iron (Fe3+) at mine sites, Fe3+ spontaneously reacts with water and iron-sulfur compounds like pyrite to produce sulfate and hydrogen ions. During this reaction ferrous iron, which can be utilized by Ferroplasma, is also regenerated leading to a "propagation cycle" where pH is lowered. The reaction can be described by the following equation: FeS2 + 14Fe^3+ + 8H2O-> 15Fe^2+ + 2SO4^2- + 16H+ Ferroplasma species are often present at AMD sites where they participate in this cycle through the biotic oxidation of ferrous iron. Ferroplasma sp. may have important applications for bioleaching metals. Microbial bioleaching occurs naturally in the highly acidic environments that are home to Ferroplasma sp. Harnessing the power of bioleaching to recover metal from low quality ores and waste material