Lithoautotroph

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A lithoautotroph or chemolithoautotroph is a microbe which derives energy from reactions of reduced compounds of mineral origin. Chemolithoautotrophs are types of lithotrophs with autotrophic metabolic pathways. Chemolithoautotrophs are exclusively microbes; macrofauna include photolithoautotrophs such as plants but do not possess the capability to use mineral sources of reduced compounds. Most chemolithoautotrophs belong to the domain Bacteria, while some belong to the domain Archaea. Lithoautotrophic bacteria can only use inorganic molecules as substrates in their energy-releasing reactions. The term "lithotroph" is from Greek lithos (λίθος) meaning "rock" and trōphos (τροφοσ) meaning "consumer"; literally, it may be read "eaters of rock". Many lithoautotrophs are extremophiles, but this is not universally so.

Lithoautotrophs are extremely specific in their source of reduced compounds. Thus, despite the diversity in using inorganic compounds that lithoautotrophs exhibit as a group, one particular lithoautotroph would use only one type of inorganic molecule to get its energy.

In July 2020 researchers report the discovery of chemolithoautotrophic bacterial culture that feeds on the metal manganese after performing unrelated experiments and named its bacterial species Candidatus Manganitrophus noduliformans and Ramlibacter lithotrophicus.[1][2][3]

Geological processes[]

Lithoautotrophs participate in many geological processes, such as the weathering of parent material (bedrock) to form soil, as well as biogeochemical cycling of sulfur, potassium, and other elements. They may be present in the deep terrestrial subsurface (they have been found well over 3 km below the surface of the planet), in soils, and in endolith communities. As they are responsible for the liberation of many crucial nutrients, and participate in the formation of soil, lithoautotrophs play a crucial role in the maintenance of life on Earth.

Acid mine drainage[]

Main article: Acid mine drainage

Lithoautotrophic microbial consortia are responsible for the phenomenon known as acid mine drainage, whereby pyrite present in mine tailing heaps and in exposed rock faces is metabolized, using energy-rich oxygen,[4] to produce sulfites, which form potentially corrosive sulfuric acid when dissolved in water and exposed to aerial oxygen. Acid mine drainage drastically alters the acidity and chemistry of groundwater and streams, and may endanger plant and animal populations. Activity similar to acid mine drainage, but on a much lower scale, is also found in natural conditions such as the rocky beds of glaciers, in soil and talus, and in the deep subsurface.

References[]

  1. ^ "Bacteria with a metal diet discovered in dirty glassware". phys.org. Retrieved 16 August 2020.
  2. ^ Woodyatt, Amy. "Bacteria that eats metal accidentally discovered by scientists". CNN. Retrieved 16 August 2020.
  3. ^ Yu, Hang; Leadbetter, Jared R. (July 2020). "Bacterial chemolithoautotrophy via manganese oxidation". Nature. 583 (7816): 453–458. doi:10.1038/s41586-020-2468-5. ISSN 1476-4687. PMC 7802741.
  4. ^ Schmidt-Rohr, K. (2020). "Oxygen Is the High-Energy Molecule Powering Complex Multicellular Life: Fundamental Corrections to Traditional Bioenergetics". ACS Omega 5: 2221-2233. http://dx.doi.org/10.1021/acsomega.9b03352
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