Decoupling microbial iron reduction from anoxic microsite formation in oxic sediments: a microscale investigation through microfluidic models
Iron (Fe) reduction is one of the oldest microbial processes on Earth. After the atmosphere and ocean became oxygenated, this anaerobic process was relegated to niche anoxic environments. However, evidence of Fe reduction in oxic, partially saturated subsurface systems, such as soils and vadose zone...
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Frontiers Media S.A.
2025-01-01
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| Series: | Frontiers in Microbiology |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/fmicb.2025.1504111/full |
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| author | Giulia Ceriotti Alice Bosco-Santos Sergey M. Borisov Jasmine S. Berg |
| author_facet | Giulia Ceriotti Alice Bosco-Santos Sergey M. Borisov Jasmine S. Berg |
| author_sort | Giulia Ceriotti |
| collection | DOAJ |
| description | Iron (Fe) reduction is one of the oldest microbial processes on Earth. After the atmosphere and ocean became oxygenated, this anaerobic process was relegated to niche anoxic environments. However, evidence of Fe reduction in oxic, partially saturated subsurface systems, such as soils and vadose zones, has been reported, with the common explanation being the formation of anoxic microsites that remain undetected by bulk measurements. To explore how microscale oxygen concentrations regulate microbial Fe reduction, we cultivated a facultative Fe-reducing bacterium using a microfluidic setup integrated with transparent planar oxygen sensors. Contrary to expectations, Fe reduction occurred under fully oxic conditions, without the formation of anoxic microsites. Our results suggest that microbially mediated Fe-reduction could be more widespread in oxic subsurface environments than previously assumed. Moreover, our mathematical modeling of oxygen dynamics around biomass-rich layers revealed that the onset of anoxia is mainly controlled by biomass spatial organization rather than the conventionally used water saturation index. This opens a new perspective on the proxies needed to predict anoxic microsite formation and Fe(III) reduction occurrence. |
| format | Article |
| id | doaj-art-5be1f4b4f2164a7486a27e4b8be72ae5 |
| institution | Kabale University |
| issn | 1664-302X |
| language | English |
| publishDate | 2025-01-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Microbiology |
| spelling | doaj-art-5be1f4b4f2164a7486a27e4b8be72ae52025-01-28T06:41:23ZengFrontiers Media S.A.Frontiers in Microbiology1664-302X2025-01-011610.3389/fmicb.2025.15041111504111Decoupling microbial iron reduction from anoxic microsite formation in oxic sediments: a microscale investigation through microfluidic modelsGiulia Ceriotti0Alice Bosco-Santos1Sergey M. Borisov2Jasmine S. Berg3Faculty of Geoscience and Environment, Institute of Earth Surface Dynamics, University of Lausanne, Lausanne, SwitzerlandFaculty of Geoscience and Environment, Institute of Earth Surface Dynamics, University of Lausanne, Lausanne, SwitzerlandFaculty of Technical Chemistry, Chemical and Process Engineering and Biotechnology, Institute of Analytical Chemistry and Food Chemistry, Graz University of Technology, Graz, AustriaFaculty of Geoscience and Environment, Institute of Earth Surface Dynamics, University of Lausanne, Lausanne, SwitzerlandIron (Fe) reduction is one of the oldest microbial processes on Earth. After the atmosphere and ocean became oxygenated, this anaerobic process was relegated to niche anoxic environments. However, evidence of Fe reduction in oxic, partially saturated subsurface systems, such as soils and vadose zones, has been reported, with the common explanation being the formation of anoxic microsites that remain undetected by bulk measurements. To explore how microscale oxygen concentrations regulate microbial Fe reduction, we cultivated a facultative Fe-reducing bacterium using a microfluidic setup integrated with transparent planar oxygen sensors. Contrary to expectations, Fe reduction occurred under fully oxic conditions, without the formation of anoxic microsites. Our results suggest that microbially mediated Fe-reduction could be more widespread in oxic subsurface environments than previously assumed. Moreover, our mathematical modeling of oxygen dynamics around biomass-rich layers revealed that the onset of anoxia is mainly controlled by biomass spatial organization rather than the conventionally used water saturation index. This opens a new perspective on the proxies needed to predict anoxic microsite formation and Fe(III) reduction occurrence.https://www.frontiersin.org/articles/10.3389/fmicb.2025.1504111/fulliron reductionoxygenmicrofluidicsplanar sensorsdiffusionShewanella oneidensis |
| spellingShingle | Giulia Ceriotti Alice Bosco-Santos Sergey M. Borisov Jasmine S. Berg Decoupling microbial iron reduction from anoxic microsite formation in oxic sediments: a microscale investigation through microfluidic models Frontiers in Microbiology iron reduction oxygen microfluidics planar sensors diffusion Shewanella oneidensis |
| title | Decoupling microbial iron reduction from anoxic microsite formation in oxic sediments: a microscale investigation through microfluidic models |
| title_full | Decoupling microbial iron reduction from anoxic microsite formation in oxic sediments: a microscale investigation through microfluidic models |
| title_fullStr | Decoupling microbial iron reduction from anoxic microsite formation in oxic sediments: a microscale investigation through microfluidic models |
| title_full_unstemmed | Decoupling microbial iron reduction from anoxic microsite formation in oxic sediments: a microscale investigation through microfluidic models |
| title_short | Decoupling microbial iron reduction from anoxic microsite formation in oxic sediments: a microscale investigation through microfluidic models |
| title_sort | decoupling microbial iron reduction from anoxic microsite formation in oxic sediments a microscale investigation through microfluidic models |
| topic | iron reduction oxygen microfluidics planar sensors diffusion Shewanella oneidensis |
| url | https://www.frontiersin.org/articles/10.3389/fmicb.2025.1504111/full |
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