A Microbial Biorealm page on the Ferroplasma
Higher order taxa:
Archaea; Euryarchaeota; Thermoplasmata; Thermoplasmatales; Ferroplasmaceae
Ferroplasma acidiphilum YT, F. acidarmanus
Description and Significance
Ferroplasma spp. are acidophilic microorganisms that help accelerate the rate of disintegration of metal sulfide minerals . The oxidative disintegration of Sulfides (primarily pyrite, FeS2) plays an important role in the geochemical sulfur cycle and causes the formation of acid mine drainage (AMD). Ferroplasma helps precipitate the rate of pyrite through regeneration of Fe3+, the primary pyrite oxidant at low pH.
No Ferroplasma spp. has been sequenced yet (F. acidarmanus sequencing is in progress), although certain genes have been investigated such as the genes responsible for arsenic resistance in F. acidarmanus. Gihring et al. (2003) discovered that some of the known arsenic resistance genes were not present in F. acidarmanus, indicating the presence of other unknown arsenic-resistance genes.
Cell Structure and Metabolism
F. acidiphilum cells during exponential phase are pleomorphic in shape and are 0.4-0.9 um in length. They also have membrane bound electron-transport zones and no cell wall.
Sulfides exposed to air and water undergo oxidative dissolution by the reaction FeS2 + 14Fe3+ + 8H2O → 15Fe2+ +2SO42- + 16H+. By producing Fe3+, Ferroplasma is able to drive this reaction forward, oxidizing FeS2.
Both Ferroplasma species are heterotrophic, growing best on yeast extract. These species are also aerobic, requiring oxygen for growth.
Ferroplasma has been located at Iron Mountain in northern California. It can grow where the temperature is between 15 and 47oC, with an optimum temperature of 35-36oC, and where the pH is between 1.3 and 2.2, with an optimum pH of 1.7.
Pivovarova et al. 2002. Phenotypic Features of Ferroplasma acidiphilum Strains YT and Y-2. Microbiology Vol. 71 No. 6: 698-706.
Edwards et al. 2000. An Archaeal Iron-Oxidizing Extreme Acidophile Important in Acid Mine Drainage. Science Vol 287: 1796-1799.
Gihring et al. 2003. Arsenic resistance in the archaeon "Ferroplasma acidarmanus": new insights into the structure and evolution of the ars genes. Extremophiles Vol. 7 Iss. 2: 123-130.