Large sulfur isotope fractionation by bacterial sulfide oxidation.

Pellerin, André; Antler, Gilad; Holm, Simon Agner; Findlay, Alyssa J; Crockford, Peter W; Turchyn, Alexandra V; Jørgensen, Bo Barker; Finster, Kai · Sci Adv · 2019

basic_science · Level V

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Abstract

A sulfide-oxidizing microorganism, <i>Desulfurivibrio alkaliphilus</i> (DA), generates a consistent enrichment of sulfur-34 (<sup>34</sup> <i>S</i>) in the produced sulfate of +12.5 per mil or greater. This observation challenges the general consensus that the microbial oxidation of sulfide does not result in large <sup>34</sup> <i>S</i> enrichments and suggests that sedimentary sulfides and sulfates may be influenced by metabolic activity associated with sulfide oxidation. Since the DA-type sulfide oxidation pathway is ubiquitous in sediments, in the modern environment, and throughout Earth history, the enrichments and depletions in <sup>34</sup> <i>S</i> in sediments may be the combined result of three microbial metabolisms: microbial sulfate reduction, the disproportionation of external sulfur intermediates, and microbial sulfide oxidation.

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