Sulfur microenvironments as hotspots for biogenic pyrite formation

Abstract Pyrite (FeS2) is the end-product of bacterial sulfur cycling in reduced sedimentary environments. Sulfate-reducing bacteria (SRB) are mostly considered for biogenic pyrite formation due to their significant contribution to sulfide production at ambient temperatures. However, most experiment...

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Main Authors: Fatih Sekerci, Stefan Fischer, Prachi Joshi, Stefan Peiffer, Andreas Kappler, Muammar Mansor
Format: Article
Language:English
Published: Nature Portfolio 2025-06-01
Series:Scientific Reports
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Online Access:https://doi.org/10.1038/s41598-025-05178-8
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author Fatih Sekerci
Stefan Fischer
Prachi Joshi
Stefan Peiffer
Andreas Kappler
Muammar Mansor
author_facet Fatih Sekerci
Stefan Fischer
Prachi Joshi
Stefan Peiffer
Andreas Kappler
Muammar Mansor
author_sort Fatih Sekerci
collection DOAJ
description Abstract Pyrite (FeS2) is the end-product of bacterial sulfur cycling in reduced sedimentary environments. Sulfate-reducing bacteria (SRB) are mostly considered for biogenic pyrite formation due to their significant contribution to sulfide production at ambient temperatures. However, most experiments using SRB for biogenic pyrite formation resulted in the formation of only metastable iron sulfide minerals such as mackinawite (FeS). In this study, we investigated the roles of elemental sulfur (S0) and microbial sulfur reduction for pyrite formation. To this end, we cultivated the Fe(III)- and sulfur-reducing bacterium Geobacter sulfurreducens in the presence of the Fe(III) (oxyhydr)oxide mineral ferrihydrite and elemental sulfur at two different Fe/S ratios (4:1 and 1:4). While only mackinawite formed in Fe/S: 4:1 experiments, sulfidic conditions in the Fe/S: 1:4 experiments favored greigite (Fe3S4) and pyrite formation via the polysulfide pathway. Morphological observations demonstrated that spherulitic pyrite particles formed at the surface of elemental sulfur, with clusters forming that preserved the original morphology of sulfur particles. Our results showed that sulfur-reducing bacteria could replace the role of SRB as a sulfide source and further showed that sulfur particles are likely hotspots for biogenic pyrite formation by creating polysulfide-rich microenvironments and by acting as templates for spatially heterogeneous pyrite precipitation in nature.
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spelling doaj-art-09a7f6b9bd894cf9a99a4a965d0a7b152025-08-20T02:36:50ZengNature PortfolioScientific Reports2045-23222025-06-0115111110.1038/s41598-025-05178-8Sulfur microenvironments as hotspots for biogenic pyrite formationFatih Sekerci0Stefan Fischer1Prachi Joshi2Stefan Peiffer3Andreas Kappler4Muammar Mansor5Geomicrobiology, Department of Geosciences, University of TuebingenTuebingen Structural Microscopy Core Facility, University of TuebingenGeomicrobiology, Department of Geosciences, University of TuebingenHydrology, Bayreuth Center for Ecology and Environmental Science, University of BayreuthGeomicrobiology, Department of Geosciences, University of TuebingenGeomicrobiology, Department of Geosciences, University of TuebingenAbstract Pyrite (FeS2) is the end-product of bacterial sulfur cycling in reduced sedimentary environments. Sulfate-reducing bacteria (SRB) are mostly considered for biogenic pyrite formation due to their significant contribution to sulfide production at ambient temperatures. However, most experiments using SRB for biogenic pyrite formation resulted in the formation of only metastable iron sulfide minerals such as mackinawite (FeS). In this study, we investigated the roles of elemental sulfur (S0) and microbial sulfur reduction for pyrite formation. To this end, we cultivated the Fe(III)- and sulfur-reducing bacterium Geobacter sulfurreducens in the presence of the Fe(III) (oxyhydr)oxide mineral ferrihydrite and elemental sulfur at two different Fe/S ratios (4:1 and 1:4). While only mackinawite formed in Fe/S: 4:1 experiments, sulfidic conditions in the Fe/S: 1:4 experiments favored greigite (Fe3S4) and pyrite formation via the polysulfide pathway. Morphological observations demonstrated that spherulitic pyrite particles formed at the surface of elemental sulfur, with clusters forming that preserved the original morphology of sulfur particles. Our results showed that sulfur-reducing bacteria could replace the role of SRB as a sulfide source and further showed that sulfur particles are likely hotspots for biogenic pyrite formation by creating polysulfide-rich microenvironments and by acting as templates for spatially heterogeneous pyrite precipitation in nature.https://doi.org/10.1038/s41598-025-05178-8Biogenic pyrite formationPyrite spherulesMicroenvironmentPolysulfideSulfidic conditionsGeobacter sulfurreducens
spellingShingle Fatih Sekerci
Stefan Fischer
Prachi Joshi
Stefan Peiffer
Andreas Kappler
Muammar Mansor
Sulfur microenvironments as hotspots for biogenic pyrite formation
Scientific Reports
Biogenic pyrite formation
Pyrite spherules
Microenvironment
Polysulfide
Sulfidic conditions
Geobacter sulfurreducens
title Sulfur microenvironments as hotspots for biogenic pyrite formation
title_full Sulfur microenvironments as hotspots for biogenic pyrite formation
title_fullStr Sulfur microenvironments as hotspots for biogenic pyrite formation
title_full_unstemmed Sulfur microenvironments as hotspots for biogenic pyrite formation
title_short Sulfur microenvironments as hotspots for biogenic pyrite formation
title_sort sulfur microenvironments as hotspots for biogenic pyrite formation
topic Biogenic pyrite formation
Pyrite spherules
Microenvironment
Polysulfide
Sulfidic conditions
Geobacter sulfurreducens
url https://doi.org/10.1038/s41598-025-05178-8
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AT prachijoshi sulfurmicroenvironmentsashotspotsforbiogenicpyriteformation
AT stefanpeiffer sulfurmicroenvironmentsashotspotsforbiogenicpyriteformation
AT andreaskappler sulfurmicroenvironmentsashotspotsforbiogenicpyriteformation
AT muammarmansor sulfurmicroenvironmentsashotspotsforbiogenicpyriteformation