Redox transformations of metals

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Reduction-Oxidation. Redox transformations of metals which have multiple valence states. Most well known are Fe and Mn. Also note:

  • Cr (Cr3+, CrO42 ); oxidation of Cr (III) appears to be exclusively abiotic; Cr(VI) reduction by bacteria is widespread and may be direct (eg acting as an electron-acceptor) or indirect (eg by S2 produced by SRB).
  • Hg (Hg0, Hg2+); elemental mercury can be oxidised by a number of metabolic products; Hg2+ reduction is enzymic (mercuric reductase) is the most common mechanism among microbes for Hg resistance.
  • U (UO2, UO22+); U(IV) is insoluble, U(VI) is soluble. Oxidation has been reported for Thiobacillus dentrificans and At. ferrooxidans and reduction by iron reducing bacteria and SRB.
  • Mo (MoO42- , Mo6+, Mo5+; microbial oxidation and reduction reported);
  • Cu (Cu2+ and Cu+; microbial oxidation and reduction reported);
  • Sb (Sb(III) and Sb(V) oxidation only);
  • Also note Au and Ag can be reduced by mercuric reductase. Passive reduction of gold (Au3+ → Au+ → Au0) by the alga Chlorella vulgaris has been reported.

See also

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