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The Microbial Ferrous Wheel in a Neutral pH Groundwater Seep
Evidence for microbial Fe redox cycling was documented in a circumneutral pH groundwater seep near Bloomington, Indiana. Geochemical and microbiological analyses were conducted at two sites, a semi-consolidated microbial mat and a floating puffball structure. In situ voltammetric microelectrode meas...
Autores principales: | , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
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Frontiers Research Foundation
2012
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3390581/ https://www.ncbi.nlm.nih.gov/pubmed/22783228 http://dx.doi.org/10.3389/fmicb.2012.00172 |
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author | Roden, Eric E. McBeth, Joyce M. Blöthe, Marco Percak-Dennett, Elizabeth M. Fleming, Emily J. Holyoke, Rebecca R. Luther, George W. Emerson, David Schieber, Juergen |
author_facet | Roden, Eric E. McBeth, Joyce M. Blöthe, Marco Percak-Dennett, Elizabeth M. Fleming, Emily J. Holyoke, Rebecca R. Luther, George W. Emerson, David Schieber, Juergen |
author_sort | Roden, Eric E. |
collection | PubMed |
description | Evidence for microbial Fe redox cycling was documented in a circumneutral pH groundwater seep near Bloomington, Indiana. Geochemical and microbiological analyses were conducted at two sites, a semi-consolidated microbial mat and a floating puffball structure. In situ voltammetric microelectrode measurements revealed steep opposing gradients of O(2) and Fe(II) at both sites, similar to other groundwater seep and sedimentary environments known to support microbial Fe redox cycling. The puffball structure showed an abrupt increase in dissolved Fe(II) just at its surface (∼5 cm depth), suggesting an internal Fe(II) source coupled to active Fe(III) reduction. Most probable number enumerations detected microaerophilic Fe(II)-oxidizing bacteria (FeOB) and dissimilatory Fe(III)-reducing bacteria (FeRB) at densities of 10(2) to 10(5) cells mL(−1) in samples from both sites. In vitro Fe(III) reduction experiments revealed the potential for immediate reduction (no lag period) of native Fe(III) oxides. Conventional full-length 16S rRNA gene clone libraries were compared with high throughput barcode sequencing of the V1, V4, or V6 variable regions of 16S rRNA genes in order to evaluate the extent to which new sequencing approaches could provide enhanced insight into the composition of Fe redox cycling microbial community structure. The composition of the clone libraries suggested a lithotroph-dominated microbial community centered around taxa related to known FeOB (e.g., Gallionella, Sideroxydans, Aquabacterium). Sequences related to recognized FeRB (e.g., Rhodoferax, Aeromonas, Geobacter, Desulfovibrio) were also well-represented. Overall, sequences related to known FeOB and FeRB accounted for 88 and 59% of total clone sequences in the mat and puffball libraries, respectively. Taxa identified in the barcode libraries showed partial overlap with the clone libraries, but were not always consistent across different variable regions and sequencing platforms. However, the barcode libraries provided confirmation of key clone library results (e.g., the predominance of Betaproteobacteria) and an expanded view of lithotrophic microbial community composition. |
format | Online Article Text |
id | pubmed-3390581 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2012 |
publisher | Frontiers Research Foundation |
record_format | MEDLINE/PubMed |
spelling | pubmed-33905812012-07-10 The Microbial Ferrous Wheel in a Neutral pH Groundwater Seep Roden, Eric E. McBeth, Joyce M. Blöthe, Marco Percak-Dennett, Elizabeth M. Fleming, Emily J. Holyoke, Rebecca R. Luther, George W. Emerson, David Schieber, Juergen Front Microbiol Microbiology Evidence for microbial Fe redox cycling was documented in a circumneutral pH groundwater seep near Bloomington, Indiana. Geochemical and microbiological analyses were conducted at two sites, a semi-consolidated microbial mat and a floating puffball structure. In situ voltammetric microelectrode measurements revealed steep opposing gradients of O(2) and Fe(II) at both sites, similar to other groundwater seep and sedimentary environments known to support microbial Fe redox cycling. The puffball structure showed an abrupt increase in dissolved Fe(II) just at its surface (∼5 cm depth), suggesting an internal Fe(II) source coupled to active Fe(III) reduction. Most probable number enumerations detected microaerophilic Fe(II)-oxidizing bacteria (FeOB) and dissimilatory Fe(III)-reducing bacteria (FeRB) at densities of 10(2) to 10(5) cells mL(−1) in samples from both sites. In vitro Fe(III) reduction experiments revealed the potential for immediate reduction (no lag period) of native Fe(III) oxides. Conventional full-length 16S rRNA gene clone libraries were compared with high throughput barcode sequencing of the V1, V4, or V6 variable regions of 16S rRNA genes in order to evaluate the extent to which new sequencing approaches could provide enhanced insight into the composition of Fe redox cycling microbial community structure. The composition of the clone libraries suggested a lithotroph-dominated microbial community centered around taxa related to known FeOB (e.g., Gallionella, Sideroxydans, Aquabacterium). Sequences related to recognized FeRB (e.g., Rhodoferax, Aeromonas, Geobacter, Desulfovibrio) were also well-represented. Overall, sequences related to known FeOB and FeRB accounted for 88 and 59% of total clone sequences in the mat and puffball libraries, respectively. Taxa identified in the barcode libraries showed partial overlap with the clone libraries, but were not always consistent across different variable regions and sequencing platforms. However, the barcode libraries provided confirmation of key clone library results (e.g., the predominance of Betaproteobacteria) and an expanded view of lithotrophic microbial community composition. Frontiers Research Foundation 2012-05-22 /pmc/articles/PMC3390581/ /pubmed/22783228 http://dx.doi.org/10.3389/fmicb.2012.00172 Text en Copyright © 2012 Roden, McBeth, Blöthe, Percak-Dennett, Fleming, Holyoke, Luther III, Emerson and Schieber. http://www.frontiersin.org/licenseagreement This is an open-access article distributed under the terms of the Creative Commons Attribution Non Commercial License, which permits non-commercial use, distribution, and reproduction in other forums, provided the original authors and source are credited. |
spellingShingle | Microbiology Roden, Eric E. McBeth, Joyce M. Blöthe, Marco Percak-Dennett, Elizabeth M. Fleming, Emily J. Holyoke, Rebecca R. Luther, George W. Emerson, David Schieber, Juergen The Microbial Ferrous Wheel in a Neutral pH Groundwater Seep |
title | The Microbial Ferrous Wheel in a Neutral pH Groundwater Seep |
title_full | The Microbial Ferrous Wheel in a Neutral pH Groundwater Seep |
title_fullStr | The Microbial Ferrous Wheel in a Neutral pH Groundwater Seep |
title_full_unstemmed | The Microbial Ferrous Wheel in a Neutral pH Groundwater Seep |
title_short | The Microbial Ferrous Wheel in a Neutral pH Groundwater Seep |
title_sort | microbial ferrous wheel in a neutral ph groundwater seep |
topic | Microbiology |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3390581/ https://www.ncbi.nlm.nih.gov/pubmed/22783228 http://dx.doi.org/10.3389/fmicb.2012.00172 |
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