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Long-distance electron transfer by cable bacteria in aquifer sediments

The biodegradation of organic pollutants in aquifers is often restricted to the fringes of contaminant plumes where steep countergradients of electron donors and acceptors are separated by limited dispersive mixing. However, long-distance electron transfer (LDET) by filamentous ‘cable bacteria'...

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Autores principales: Müller, Hubert, Bosch, Julian, Griebler, Christian, Damgaard, Lars Riis, Nielsen, Lars Peter, Lueders, Tillmann, Meckenstock, Rainer U
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4939269/
https://www.ncbi.nlm.nih.gov/pubmed/27058505
http://dx.doi.org/10.1038/ismej.2015.250
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author Müller, Hubert
Bosch, Julian
Griebler, Christian
Damgaard, Lars Riis
Nielsen, Lars Peter
Lueders, Tillmann
Meckenstock, Rainer U
author_facet Müller, Hubert
Bosch, Julian
Griebler, Christian
Damgaard, Lars Riis
Nielsen, Lars Peter
Lueders, Tillmann
Meckenstock, Rainer U
author_sort Müller, Hubert
collection PubMed
description The biodegradation of organic pollutants in aquifers is often restricted to the fringes of contaminant plumes where steep countergradients of electron donors and acceptors are separated by limited dispersive mixing. However, long-distance electron transfer (LDET) by filamentous ‘cable bacteria' has recently been discovered in marine sediments to couple spatially separated redox half reactions over centimeter scales. Here we provide primary evidence that such sulfur-oxidizing cable bacteria can also be found at oxic–anoxic interfaces in aquifer sediments, where they provide a means for the direct recycling of sulfate by electron transfer over 1–2-cm distance. Sediments were taken from a hydrocarbon-contaminated aquifer, amended with iron sulfide and saturated with water, leaving the sediment surface exposed to air. Steep geochemical gradients developed in the upper 3 cm, showing a spatial separation of oxygen and sulfide by 9 mm together with a pH profile characteristic for sulfur oxidation by LDET. Bacterial filaments, which were highly abundant in the suboxic zone, were identified by sequencing of 16S rRNA genes and fluorescence in situ hybridization (FISH) as cable bacteria belonging to the Desulfobulbaceae. The detection of similar Desulfobulbaceae at the oxic–anoxic interface of fresh sediment cores taken at a contaminated aquifer suggests that LDET may indeed be active at the capillary fringe in situ.
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spelling pubmed-49392692016-09-21 Long-distance electron transfer by cable bacteria in aquifer sediments Müller, Hubert Bosch, Julian Griebler, Christian Damgaard, Lars Riis Nielsen, Lars Peter Lueders, Tillmann Meckenstock, Rainer U ISME J Original Article The biodegradation of organic pollutants in aquifers is often restricted to the fringes of contaminant plumes where steep countergradients of electron donors and acceptors are separated by limited dispersive mixing. However, long-distance electron transfer (LDET) by filamentous ‘cable bacteria' has recently been discovered in marine sediments to couple spatially separated redox half reactions over centimeter scales. Here we provide primary evidence that such sulfur-oxidizing cable bacteria can also be found at oxic–anoxic interfaces in aquifer sediments, where they provide a means for the direct recycling of sulfate by electron transfer over 1–2-cm distance. Sediments were taken from a hydrocarbon-contaminated aquifer, amended with iron sulfide and saturated with water, leaving the sediment surface exposed to air. Steep geochemical gradients developed in the upper 3 cm, showing a spatial separation of oxygen and sulfide by 9 mm together with a pH profile characteristic for sulfur oxidation by LDET. Bacterial filaments, which were highly abundant in the suboxic zone, were identified by sequencing of 16S rRNA genes and fluorescence in situ hybridization (FISH) as cable bacteria belonging to the Desulfobulbaceae. The detection of similar Desulfobulbaceae at the oxic–anoxic interface of fresh sediment cores taken at a contaminated aquifer suggests that LDET may indeed be active at the capillary fringe in situ. Nature Publishing Group 2016-08 2016-04-08 /pmc/articles/PMC4939269/ /pubmed/27058505 http://dx.doi.org/10.1038/ismej.2015.250 Text en Copyright © 2016 International Society for Microbial Ecology http://creativecommons.org/licenses/by/4.0/ This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/
spellingShingle Original Article
Müller, Hubert
Bosch, Julian
Griebler, Christian
Damgaard, Lars Riis
Nielsen, Lars Peter
Lueders, Tillmann
Meckenstock, Rainer U
Long-distance electron transfer by cable bacteria in aquifer sediments
title Long-distance electron transfer by cable bacteria in aquifer sediments
title_full Long-distance electron transfer by cable bacteria in aquifer sediments
title_fullStr Long-distance electron transfer by cable bacteria in aquifer sediments
title_full_unstemmed Long-distance electron transfer by cable bacteria in aquifer sediments
title_short Long-distance electron transfer by cable bacteria in aquifer sediments
title_sort long-distance electron transfer by cable bacteria in aquifer sediments
topic Original Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4939269/
https://www.ncbi.nlm.nih.gov/pubmed/27058505
http://dx.doi.org/10.1038/ismej.2015.250
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