Dissimilatory metal-reducing bacteria

Dissimilatory metal-reducing bacteria (DMRB) are a class of bacteria that couple the oxidation of organic matter to the reduction of a metal species in the process of anaerobic respiration.[1] Species that typically use ferric iron as an electron acceptor are also known as dissimilatory iron-reducing bacteria (DIRB). In addition to Bacteria, some Archaea also perform dissimilatory iron (III) reduction, which suggests that microbial iron respiration may be one of the oldest forms of metabolism on earth.[2]

Conditions for dissimilatory metal reduction

DMRB include both obligate (strict) anaerobes, such as the Geobacteraceae family, and facultative anaerobes, such as Shewanella spp. Some species of DMRB produce compounds that act as electron shuttles, enabling them to perform metal reduction from a distance. Other organic compounds frequently found in soils and sediments, such as humic acids, may also act as electron shuttles.[3]

Terminal electron acceptors

A wide range of Fe(III)-bearing minerals have been observed to function as terminal electron acceptors, including magnetite, hematite, goethite, lepidocrocite, ferrihydrite, hydrous ferric oxide, smectite, illite, jarosite, among others.[4]

Secondary mineral formation

In natural systems, secondary minerals may form as a byproduct of bacterial metal reduction.[5] Commonly observed secondary minerals produced during experimental bio-reduction by DMRB include magnetite, siderite, green rust, vivianite, and hydrous Fe(II)-carbonate.

Genera that include DMRB

References

  1. ↑ Lovley, D. R. (1991). Dissimilatory Fe (III) and Mn (IV) reduction. Microbiological reviews, 55(2), 259.
  2. ↑ Vargas, Madeline, Kazem Kashefi, Elizabeth L. Blunt-Harris, and Derek R. Lovley. "Microbiological evidence for Fe (III) reduction on early Earth." Nature 395, no. 6697 (1998): 65-67.
  3. ↑ Lovley, D. R., Fraga, J. L., Blunt-Harris, E. L., Hayes, L. A., Phillips, E. J. P., & Coates, J. D. (1998). Humic substances as a mediator for microbially catalyzed metal reduction. Acta hydrochimica et hydrobiologica, 26(3), 152-157.
  4. ↑ Miot, J., & Etique, M. (2016). Formation and Transformation of Iron‐Bearing Minerals by Iron (II)‐Oxidizing and Iron (III)‐Reducing Bacteria. Iron Oxides: From Nature to Applications, 53-98.
  5. ↑ Lovley, D. R., Stolz, J. F., Nord, G. L., & Phillips, E. J. (1987). Anaerobic production of magnetite by a dissimilatory iron-reducing microorganism. Nature, 330(6145), 252-254


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