A bacterial isolate from the Black Sea oxidizes sulfide with manganese(IV) oxide.

Henkel, Jan V; Dellwig, Olaf; Pollehne, Falk; Herlemann, Daniel P R; Leipe, Thomas; Schulz-Vogt, Heide N · Proc Natl Acad Sci U S A · 2019

basic_science · Level V

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Abstract

Mn is one of the most abundant redox-sensitive metals on earth. Some microorganisms are known to use Mn(IV) oxide (MnO<sub>2</sub>) as electron acceptor for the oxidation of organic compounds or hydrogen (H<sub>2</sub>), but so far the use of sulfide (H<sub>2</sub>S) has been suggested but not proven. Here we report on a bacterial isolate which grows autotrophically and couples the reduction of MnO<sub>2</sub> to the oxidation of H<sub>2</sub>S or thiosulfate (S<sub>2</sub>O<sub>3</sub><sup>2−</sup>) for energy generation. The isolate, originating from the Black Sea, is a species within the genus <i>Sulfurimonas</i>, which typically occurs with high cell numbers in the vicinity of sulfidic environments [Y. Han, M. Perner, <i>Front. Microbiol.</i> 6, 989 (2015)]. H<sub>2</sub>S and S<sub>2</sub>O<sub>3</sub><sup>2−</sup> are oxidized completely to sulfate (SO<sub>4</sub><sup>2−</sup>) without the accumulation of intermediates. In the culture, Mn(IV) reduction proceeds via Mn(III) and finally precipitation of Ca-rich Mn(II) carbonate [Mn(Ca)CO<sub>3</sub>]. In contrast to Mn-reducing bacteria, which use organic electron donors or H<sub>2</sub>, Fe oxides are not observed to support growth, which may either indicate an incomplete gene set or a different pathway for extracellular electron transfer.

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