High biological N fixation potential dominated by heterotrophic diazotrophs in alpine permafrost rivers on the Qinghai‒Tibet Plateau.
Biological nitrogen (N) fixation is a pivotal N source in N-deficient ecosystems. The Qinghai‒Tibet Plateau (QTP) region, which is assumed to be N limited and suboxic, is an ideal habitat for diazotrophs. However, the diazotrophic communities and associated N fixation rates in these high-altitude al...
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ftpubmed:39137482 2024-09-30T14:41:13+00:00 High biological N fixation potential dominated by heterotrophic diazotrophs in alpine permafrost rivers on the Qinghai‒Tibet Plateau. Xin, Yuan Gao, Qun Chen, Xin Sun, Siyue Liu, Jiao Gao, Hui Zhou, Jizhong Xia, Xinghui 2024 Oct 15 https://doi.org/10.1016/j.watres.2024.122239 https://pubmed.ncbi.nlm.nih.gov/39137482 eng eng Elsevier Science https://doi.org/10.1016/j.watres.2024.122239 https://pubmed.ncbi.nlm.nih.gov/39137482 Copyright © 2024 Elsevier Ltd. All rights reserved. Water Res ISSN:1879-2448 Volume:264 Alpine permafrost river Biological N fixation Heterotrophic diazotrophs Nitrogen cycling Qinghai‒Tibet Plateau Journal Article 2024 ftpubmed https://doi.org/10.1016/j.watres.2024.122239 2024-08-31T16:02:00Z Biological nitrogen (N) fixation is a pivotal N source in N-deficient ecosystems. The Qinghai‒Tibet Plateau (QTP) region, which is assumed to be N limited and suboxic, is an ideal habitat for diazotrophs. However, the diazotrophic communities and associated N fixation rates in these high-altitude alpine permafrost QTP rivers remain largely unknown. Herein, we examined diazotrophic communities in the sediment and biofilm of QTP rivers via the nitrogenase (nifH) gene sequencing and assessed their N fixing activities via a 15N isotope incubation assay. Strikingly, anaerobic heterotrophic diazotrophs, such as sulfate- and iron-reducing bacteria, had emerged as dominant N fixers. Remarkably, the nifH gene abundance and N fixation rates increased with altitude, and the average nifH gene abundance (2.57 ± 2.60 × 108 copies g-1) and N fixation rate (2.29 ± 3.36 nmol N g-1d-1) surpassed that documented in most aquatic environments (nifH gene abundance: 1.31 × 105 ∼ 2.57 × 108 copies g-1, nitrogen fixation rates: 2.34 × 10-4 ∼ 4.11 nmol N g-1d-1). Such distinctive heterotrophic diazotrophic communities and high N fixation potential in QTP rivers were associated with low-nitrogen, abundant organic carbon and unique C:N:P stoichiometries. Additionally, the significant presence of psychrophilic bacteria within the diazotrophic communities, along with the enhanced stability and complexity of the diazotrophic networks at higher altitudes, clearly demonstrate the adaptability of diazotrophic communities to extreme cold and high-altitude conditions in QTP rivers. We further determined that altitude, coupled with organic carbon and phosphorus, was the predominant driver shaping diazotrophic communities and their N-fixing activities. Overall, our study reveals high N fixation potential in N-deficient QTP rivers, which provides novel insights into nitrogen dynamics in alpine permafrost rivers. Article in Journal/Newspaper permafrost PubMed Central (PMC) Water Research 264 122239 |
institution |
Open Polar |
collection |
PubMed Central (PMC) |
op_collection_id |
ftpubmed |
language |
English |
topic |
Alpine permafrost river Biological N fixation Heterotrophic diazotrophs Nitrogen cycling Qinghai‒Tibet Plateau |
spellingShingle |
Alpine permafrost river Biological N fixation Heterotrophic diazotrophs Nitrogen cycling Qinghai‒Tibet Plateau Xin, Yuan Gao, Qun Chen, Xin Sun, Siyue Liu, Jiao Gao, Hui Zhou, Jizhong Xia, Xinghui High biological N fixation potential dominated by heterotrophic diazotrophs in alpine permafrost rivers on the Qinghai‒Tibet Plateau. |
topic_facet |
Alpine permafrost river Biological N fixation Heterotrophic diazotrophs Nitrogen cycling Qinghai‒Tibet Plateau |
description |
Biological nitrogen (N) fixation is a pivotal N source in N-deficient ecosystems. The Qinghai‒Tibet Plateau (QTP) region, which is assumed to be N limited and suboxic, is an ideal habitat for diazotrophs. However, the diazotrophic communities and associated N fixation rates in these high-altitude alpine permafrost QTP rivers remain largely unknown. Herein, we examined diazotrophic communities in the sediment and biofilm of QTP rivers via the nitrogenase (nifH) gene sequencing and assessed their N fixing activities via a 15N isotope incubation assay. Strikingly, anaerobic heterotrophic diazotrophs, such as sulfate- and iron-reducing bacteria, had emerged as dominant N fixers. Remarkably, the nifH gene abundance and N fixation rates increased with altitude, and the average nifH gene abundance (2.57 ± 2.60 × 108 copies g-1) and N fixation rate (2.29 ± 3.36 nmol N g-1d-1) surpassed that documented in most aquatic environments (nifH gene abundance: 1.31 × 105 ∼ 2.57 × 108 copies g-1, nitrogen fixation rates: 2.34 × 10-4 ∼ 4.11 nmol N g-1d-1). Such distinctive heterotrophic diazotrophic communities and high N fixation potential in QTP rivers were associated with low-nitrogen, abundant organic carbon and unique C:N:P stoichiometries. Additionally, the significant presence of psychrophilic bacteria within the diazotrophic communities, along with the enhanced stability and complexity of the diazotrophic networks at higher altitudes, clearly demonstrate the adaptability of diazotrophic communities to extreme cold and high-altitude conditions in QTP rivers. We further determined that altitude, coupled with organic carbon and phosphorus, was the predominant driver shaping diazotrophic communities and their N-fixing activities. Overall, our study reveals high N fixation potential in N-deficient QTP rivers, which provides novel insights into nitrogen dynamics in alpine permafrost rivers. |
format |
Article in Journal/Newspaper |
author |
Xin, Yuan Gao, Qun Chen, Xin Sun, Siyue Liu, Jiao Gao, Hui Zhou, Jizhong Xia, Xinghui |
author_facet |
Xin, Yuan Gao, Qun Chen, Xin Sun, Siyue Liu, Jiao Gao, Hui Zhou, Jizhong Xia, Xinghui |
author_sort |
Xin, Yuan |
title |
High biological N fixation potential dominated by heterotrophic diazotrophs in alpine permafrost rivers on the Qinghai‒Tibet Plateau. |
title_short |
High biological N fixation potential dominated by heterotrophic diazotrophs in alpine permafrost rivers on the Qinghai‒Tibet Plateau. |
title_full |
High biological N fixation potential dominated by heterotrophic diazotrophs in alpine permafrost rivers on the Qinghai‒Tibet Plateau. |
title_fullStr |
High biological N fixation potential dominated by heterotrophic diazotrophs in alpine permafrost rivers on the Qinghai‒Tibet Plateau. |
title_full_unstemmed |
High biological N fixation potential dominated by heterotrophic diazotrophs in alpine permafrost rivers on the Qinghai‒Tibet Plateau. |
title_sort |
high biological n fixation potential dominated by heterotrophic diazotrophs in alpine permafrost rivers on the qinghai‒tibet plateau. |
publisher |
Elsevier Science |
publishDate |
2024 |
url |
https://doi.org/10.1016/j.watres.2024.122239 https://pubmed.ncbi.nlm.nih.gov/39137482 |
genre |
permafrost |
genre_facet |
permafrost |
op_source |
Water Res ISSN:1879-2448 Volume:264 |
op_relation |
https://doi.org/10.1016/j.watres.2024.122239 https://pubmed.ncbi.nlm.nih.gov/39137482 |
op_rights |
Copyright © 2024 Elsevier Ltd. All rights reserved. |
op_doi |
https://doi.org/10.1016/j.watres.2024.122239 |
container_title |
Water Research |
container_volume |
264 |
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122239 |
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1811643637893693440 |