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Bacterial N(2)-fixation in mangrove ecosystems: insights from a diazotroph–mangrove interaction
Mangrove forests are highly productive ecosystems but represent low nutrient environments. Nitrogen availability is one of the main factors limiting mangrove growth. Diazotrophs have been identified as key organisms that provide nitrogen to these environments. N(2)-fixation by such organisms was fou...
Autores principales: | , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Frontiers Media S.A.
2015
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Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4426756/ https://www.ncbi.nlm.nih.gov/pubmed/26029186 http://dx.doi.org/10.3389/fmicb.2015.00445 |
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author | Alfaro-Espinoza, Gabriela Ullrich, Matthias S. |
author_facet | Alfaro-Espinoza, Gabriela Ullrich, Matthias S. |
author_sort | Alfaro-Espinoza, Gabriela |
collection | PubMed |
description | Mangrove forests are highly productive ecosystems but represent low nutrient environments. Nitrogen availability is one of the main factors limiting mangrove growth. Diazotrophs have been identified as key organisms that provide nitrogen to these environments. N(2)-fixation by such organisms was found to be higher in the mangrove roots than in surrounding rhizosphere. Moreover, previous studies showed that mangroves grew better in the presence of N(2)-fixers indicating a potentially mutualistic relationship. However, the molecular signals and mechanisms that govern these interactions are still poorly understood. Here we present novel insights in the interaction of a diazotroph with a mangrove species to improve our understanding of the molecular and ecophysiological relationship between these two organisms under controlled conditions. Our results showed that Marinobacterium mangrovicola is a versatile organism capable of competing with other organisms to survive for long periods in mangrove soils. N(2)-fixation by this bacterium was up-regulated in the presence of mangrove roots, indicating a possible beneficial interaction. The increase in N(2)-fixation was limited to cells of the exponential growth phase suggesting that N(2)-fixation differs over the bacterial growth cycle. Bacterial transformants harboring a transcriptional nifH::gusA fusion showed that M. mangrovicola successfully colonized mangrove roots and simultaneously conducted N(2)-fixation. The colonization process was stimulated by the lack of an external carbon source suggesting a possible mutualistic relationship. M. mangrovicola represents an interesting genetically accessible diazotroph, which colonize mangrove roots and exhibit higher N(2)-fixation in the presence of mangrove roots. Consequently, we propose this microorganism as a tool to study molecular interactions between N(2)-fixers and mangrove plants and to better understand how changes in the environment could impact these important and relatively unknown interactions. |
format | Online Article Text |
id | pubmed-4426756 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2015 |
publisher | Frontiers Media S.A. |
record_format | MEDLINE/PubMed |
spelling | pubmed-44267562015-05-29 Bacterial N(2)-fixation in mangrove ecosystems: insights from a diazotroph–mangrove interaction Alfaro-Espinoza, Gabriela Ullrich, Matthias S. Front Microbiol Microbiology Mangrove forests are highly productive ecosystems but represent low nutrient environments. Nitrogen availability is one of the main factors limiting mangrove growth. Diazotrophs have been identified as key organisms that provide nitrogen to these environments. N(2)-fixation by such organisms was found to be higher in the mangrove roots than in surrounding rhizosphere. Moreover, previous studies showed that mangroves grew better in the presence of N(2)-fixers indicating a potentially mutualistic relationship. However, the molecular signals and mechanisms that govern these interactions are still poorly understood. Here we present novel insights in the interaction of a diazotroph with a mangrove species to improve our understanding of the molecular and ecophysiological relationship between these two organisms under controlled conditions. Our results showed that Marinobacterium mangrovicola is a versatile organism capable of competing with other organisms to survive for long periods in mangrove soils. N(2)-fixation by this bacterium was up-regulated in the presence of mangrove roots, indicating a possible beneficial interaction. The increase in N(2)-fixation was limited to cells of the exponential growth phase suggesting that N(2)-fixation differs over the bacterial growth cycle. Bacterial transformants harboring a transcriptional nifH::gusA fusion showed that M. mangrovicola successfully colonized mangrove roots and simultaneously conducted N(2)-fixation. The colonization process was stimulated by the lack of an external carbon source suggesting a possible mutualistic relationship. M. mangrovicola represents an interesting genetically accessible diazotroph, which colonize mangrove roots and exhibit higher N(2)-fixation in the presence of mangrove roots. Consequently, we propose this microorganism as a tool to study molecular interactions between N(2)-fixers and mangrove plants and to better understand how changes in the environment could impact these important and relatively unknown interactions. Frontiers Media S.A. 2015-05-11 /pmc/articles/PMC4426756/ /pubmed/26029186 http://dx.doi.org/10.3389/fmicb.2015.00445 Text en Copyright © 2015 Alfaro-Espinoza and Ullrich. http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms. |
spellingShingle | Microbiology Alfaro-Espinoza, Gabriela Ullrich, Matthias S. Bacterial N(2)-fixation in mangrove ecosystems: insights from a diazotroph–mangrove interaction |
title | Bacterial N(2)-fixation in mangrove ecosystems: insights from a diazotroph–mangrove interaction |
title_full | Bacterial N(2)-fixation in mangrove ecosystems: insights from a diazotroph–mangrove interaction |
title_fullStr | Bacterial N(2)-fixation in mangrove ecosystems: insights from a diazotroph–mangrove interaction |
title_full_unstemmed | Bacterial N(2)-fixation in mangrove ecosystems: insights from a diazotroph–mangrove interaction |
title_short | Bacterial N(2)-fixation in mangrove ecosystems: insights from a diazotroph–mangrove interaction |
title_sort | bacterial n(2)-fixation in mangrove ecosystems: insights from a diazotroph–mangrove interaction |
topic | Microbiology |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4426756/ https://www.ncbi.nlm.nih.gov/pubmed/26029186 http://dx.doi.org/10.3389/fmicb.2015.00445 |
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