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Complex N acquisition by soil diazotrophs: how the ability to release exoenzymes affects N fixation by terrestrial free-living diazotrophs
Terrestrial systems support a variety of free-living soil diazotrophs, which can fix nitrogen (N) outside of plant associations. However, owing to the metabolic costs associated with N fixation, free-living soil diazotrophs likely rely on soil N to satisfy the majority of cellular N demand and only...
Autores principales: | , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Nature Publishing Group
2017
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5270568/ https://www.ncbi.nlm.nih.gov/pubmed/27898052 http://dx.doi.org/10.1038/ismej.2016.127 |
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author | Norman, Jeffrey S Friesen, Maren L |
author_facet | Norman, Jeffrey S Friesen, Maren L |
author_sort | Norman, Jeffrey S |
collection | PubMed |
description | Terrestrial systems support a variety of free-living soil diazotrophs, which can fix nitrogen (N) outside of plant associations. However, owing to the metabolic costs associated with N fixation, free-living soil diazotrophs likely rely on soil N to satisfy the majority of cellular N demand and only fix atmospheric N under certain conditions. Culture-based studies and genomic data show that many free-living soil diazotrophs can access high-molecular weight organic soil N by releasing N-acquiring enzymes such as proteases and chitinases into the extracellular environment. Here, we formally propose a N acquisition strategy used by free-living diazotrophs that accounts for high-molecular weight N acquisition through exoenzyme release by these organisms. We call this the ‘LAH N-acquisition strategy' for the preferred order of N pools used once inorganic soil N is limiting: (1) low-molecular weight organic N, (2) atmospheric N and (3) high-molecular weight organic N. In this framework, free-living diazotrophs primarily use biological N fixation (BNF) as a short-term N acquisition strategy to offset the cellular N lost in exoenzyme excretion as low-molecular weight N becomes limiting. By accounting for exoenzyme release by free-living diazotrophs within a cost–benefit framework, investigation of the LAH N acquisition strategy will contribute to a process-level understanding of BNF in soil environments. |
format | Online Article Text |
id | pubmed-5270568 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2017 |
publisher | Nature Publishing Group |
record_format | MEDLINE/PubMed |
spelling | pubmed-52705682017-02-07 Complex N acquisition by soil diazotrophs: how the ability to release exoenzymes affects N fixation by terrestrial free-living diazotrophs Norman, Jeffrey S Friesen, Maren L ISME J Perspectives Terrestrial systems support a variety of free-living soil diazotrophs, which can fix nitrogen (N) outside of plant associations. However, owing to the metabolic costs associated with N fixation, free-living soil diazotrophs likely rely on soil N to satisfy the majority of cellular N demand and only fix atmospheric N under certain conditions. Culture-based studies and genomic data show that many free-living soil diazotrophs can access high-molecular weight organic soil N by releasing N-acquiring enzymes such as proteases and chitinases into the extracellular environment. Here, we formally propose a N acquisition strategy used by free-living diazotrophs that accounts for high-molecular weight N acquisition through exoenzyme release by these organisms. We call this the ‘LAH N-acquisition strategy' for the preferred order of N pools used once inorganic soil N is limiting: (1) low-molecular weight organic N, (2) atmospheric N and (3) high-molecular weight organic N. In this framework, free-living diazotrophs primarily use biological N fixation (BNF) as a short-term N acquisition strategy to offset the cellular N lost in exoenzyme excretion as low-molecular weight N becomes limiting. By accounting for exoenzyme release by free-living diazotrophs within a cost–benefit framework, investigation of the LAH N acquisition strategy will contribute to a process-level understanding of BNF in soil environments. Nature Publishing Group 2017-02 2016-11-29 /pmc/articles/PMC5270568/ /pubmed/27898052 http://dx.doi.org/10.1038/ismej.2016.127 Text en Copyright © 2017 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 | Perspectives Norman, Jeffrey S Friesen, Maren L Complex N acquisition by soil diazotrophs: how the ability to release exoenzymes affects N fixation by terrestrial free-living diazotrophs |
title | Complex N acquisition by soil diazotrophs: how the ability to release exoenzymes affects N fixation by terrestrial free-living diazotrophs |
title_full | Complex N acquisition by soil diazotrophs: how the ability to release exoenzymes affects N fixation by terrestrial free-living diazotrophs |
title_fullStr | Complex N acquisition by soil diazotrophs: how the ability to release exoenzymes affects N fixation by terrestrial free-living diazotrophs |
title_full_unstemmed | Complex N acquisition by soil diazotrophs: how the ability to release exoenzymes affects N fixation by terrestrial free-living diazotrophs |
title_short | Complex N acquisition by soil diazotrophs: how the ability to release exoenzymes affects N fixation by terrestrial free-living diazotrophs |
title_sort | complex n acquisition by soil diazotrophs: how the ability to release exoenzymes affects n fixation by terrestrial free-living diazotrophs |
topic | Perspectives |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5270568/ https://www.ncbi.nlm.nih.gov/pubmed/27898052 http://dx.doi.org/10.1038/ismej.2016.127 |
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