1
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Cerdán-García E, Álvarez-Salgado XA, Arístegui J, Martínez-Marrero A, Benavides M. Eddy-driven diazotroph distribution in the subtropical North Atlantic: horizontal variability prevails over particle sinking speed. Commun Biol 2024; 7:929. [PMID: 39095605 PMCID: PMC11297262 DOI: 10.1038/s42003-024-06576-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2024] [Accepted: 07/11/2024] [Indexed: 08/04/2024] Open
Abstract
Mesoscale eddies influence the distribution of diazotrophic (nitrogen-fixing) cyanobacteria, impacting marine productivity and carbon export. Non-cyanobacterial diazotrophs (NCDs) are emerging as potential contributors to marine nitrogen fixation, relying on organic matter particles for resources, impacting nitrogen and carbon cycling. However, their diversity and biogeochemical importance remain poorly understood. In the subtropical North Atlantic along a single transect, this study explored the horizontal and vertical spatial variability of NCDs associated with suspended, slow-sinking, and fast-sinking particles collected with a marine snow catcher. The investigation combined amplicon sequencing with hydrographic and biogeochemical data. Cyanobacterial diazotrophs and NCDs were equally abundant, and their diversity was explained by the structure of the eddy. The unicellular symbiotic cyanobacterium UCYN-A was widespread across the eddy, whereas Trichodesmium and Crocosphaera accumulated at outer fronts. The diversity of particle-associated NCDs varied more horizontally than vertically. NCDs constituted most reads in the fast-sinking fractions, mainly comprising Alphaproteobacteria, whose abundance significantly differed from the suspended and slow-sinking fractions. Horizontally, Gammaproteobacteria and Betaproteobacteria exhibited inverse distributions, influenced by physicochemical characteristics of water intrusions at the eddy periphery. Niche differentiations across the anticyclonic eddy underscored NCD-particle associations and mesoscale dynamics, deepening our understanding of their ecological role and impact on ocean biogeochemistry.
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Affiliation(s)
- E Cerdán-García
- Aix Marseille Université, CNRS, Université de Toulon, IRD, OSU Pythéas, Mediterranean Institute of Oceanography (MIO), UM 110, 13288, Marseille, France.
- Turing Centre for Living Systems, Aix-Marseille University, 13009, Marseille, France.
| | | | - J Arístegui
- Instituto de Oceanografía y Cambio Global (IOCAG), Universidad de Las Palmas de Gran Canaria, ULPGC, Gran Canaria, Spain
| | - A Martínez-Marrero
- Instituto de Oceanografía y Cambio Global (IOCAG), Universidad de Las Palmas de Gran Canaria, ULPGC, Gran Canaria, Spain
| | - M Benavides
- Aix Marseille Université, CNRS, Université de Toulon, IRD, OSU Pythéas, Mediterranean Institute of Oceanography (MIO), UM 110, 13288, Marseille, France.
- Turing Centre for Living Systems, Aix-Marseille University, 13009, Marseille, France.
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2
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Chowdhury S, Berthelot H, Baudet C, González-Santana D, Reeder CF, L'Helguen S, Maguer JF, Löscher CR, Singh A, Blain S, Cassar N, Bonnet S, Planquette H, Benavides M. Fronts divide diazotroph communities in the Southern Indian Ocean. FEMS Microbiol Ecol 2024; 100:fiae095. [PMID: 38992179 PMCID: PMC11245648 DOI: 10.1093/femsec/fiae095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Revised: 06/20/2024] [Accepted: 07/10/2024] [Indexed: 07/13/2024] Open
Abstract
Dinitrogen (N2) fixation represents a key source of reactive nitrogen in marine ecosystems. While the process has been rather well-explored in low latitudes of the Atlantic and Pacific Oceans, other higher latitude regions and particularly the Indian Ocean have been chronically overlooked. Here, we characterize N2 fixation and diazotroph community composition across nutrient and trace metals gradients spanning the multifrontal system separating the oligotrophic waters of the Indian Ocean subtropical gyre from the high nutrient low chlorophyll waters of the Southern Ocean. We found a sharp contrasting distribution of diazotroph groups across the frontal system. Notably, cyanobacterial diazotrophs dominated north of fronts, driving high N2 fixation rates (up to 13.96 nmol N l-1 d-1) with notable peaks near the South African coast. South of the fronts non-cyanobacterial diazotrophs prevailed without significant N2 fixation activity being detected. Our results provide new crucial insights into high latitude diazotrophy in the Indian Ocean, which should contribute to improved climate model parameterization and enhanced constraints on global net primary productivity projections.
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Affiliation(s)
- Subhadeep Chowdhury
- Aix Marseille Université, CNRS, Université de Toulon, IRD, OSU Pythéas, Mediterranean Institute of Oceanography (MIO), UM 110, 13288 Marseille, France
- Turing Center for Living Systems, Aix-Marseille University, Marseille, France
| | - Hugo Berthelot
- IFREMER, DYNECO, Pelagos Laboratory, Plouzané, France
- Laboratoire des Sciences de l'Environnement Marin, IUEM, Université de Brest-UMR 6539 CNRS/UBO/IRD, Technopole Brest-Iroise, 29280 Plouzané, France
| | - Corentin Baudet
- Laboratoire des Sciences de l'Environnement Marin, IUEM, Université de Brest-UMR 6539 CNRS/UBO/IRD, Technopole Brest-Iroise, 29280 Plouzané, France
| | - David González-Santana
- Univ Brest, CNRS, IRD, IFREMER, LEMAR, F-29280 Plouzané, France
- Instituto de Oceanografía y Cambio Global, IOCAG, Universidad de Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain
| | - Christian Furbo Reeder
- Aix Marseille Université, CNRS, Université de Toulon, IRD, OSU Pythéas, Mediterranean Institute of Oceanography (MIO), UM 110, 13288 Marseille, France
- Turing Center for Living Systems, Aix-Marseille University, Marseille, France
| | - Stéphane L'Helguen
- Laboratoire des Sciences de l'Environnement Marin, IUEM, Université de Brest-UMR 6539 CNRS/UBO/IRD, Technopole Brest-Iroise, 29280 Plouzané, France
| | - Jean-François Maguer
- Laboratoire des Sciences de l'Environnement Marin, IUEM, Université de Brest-UMR 6539 CNRS/UBO/IRD, Technopole Brest-Iroise, 29280 Plouzané, France
| | - Carolin R Löscher
- Nordcee, Department of Biology, University of Southern Denmark, Odense 5230, Denmark
| | - Arvind Singh
- Geosciences Division, Physical Research Laboratory, Ahmedabad 380009, India
| | - Stéphane Blain
- Sorbonne Université, CNRS, Laboratoire d'Océanographie Microbienne (LOMIC), Observatoire Océanologique de Banyuls, 66650 Banyuls/mer, France
| | - Nicolas Cassar
- Laboratoire des Sciences de l'Environnement Marin, IUEM, Université de Brest-UMR 6539 CNRS/UBO/IRD, Technopole Brest-Iroise, 29280 Plouzané, France
- Division of Earth and Climate Sciences, Nicholas School of the Environment, Duke University, Durham, NC 27708, United States
| | - Sophie Bonnet
- Aix Marseille Université, CNRS, Université de Toulon, IRD, OSU Pythéas, Mediterranean Institute of Oceanography (MIO), UM 110, 13288 Marseille, France
| | - Hélène Planquette
- Laboratoire des Sciences de l'Environnement Marin, IUEM, Université de Brest-UMR 6539 CNRS/UBO/IRD, Technopole Brest-Iroise, 29280 Plouzané, France
| | - Mar Benavides
- Aix Marseille Université, CNRS, Université de Toulon, IRD, OSU Pythéas, Mediterranean Institute of Oceanography (MIO), UM 110, 13288 Marseille, France
- Turing Center for Living Systems, Aix-Marseille University, Marseille, France
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3
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Zehr JP, Capone DG. Unsolved mysteries in marine nitrogen fixation. Trends Microbiol 2024; 32:532-545. [PMID: 37658011 DOI: 10.1016/j.tim.2023.08.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2023] [Revised: 08/03/2023] [Accepted: 08/04/2023] [Indexed: 09/03/2023]
Abstract
Biological nitrogen (N2) fixation is critical in global biogeochemical cycles and in sustaining the productivity of the oceans. There remain many unanswered questions, unresolved hypotheses, and unchallenged paradigms. The fundamental balance of N input and losses has not been fully resolved. One of the major N2-fixers, Trichodesmium, remains an enigma with intriguing biological and ecological secrets. Cyanobacterial N2 fixation, once thought to be primarily due to free-living cyanobacteria, now also appears to be dependent on microbial interactions, from microbiomes to unicellular symbioses, which remain poorly characterized. Nitrogenase genes associated with diverse non-cyanobacterial diazotrophs (NCDs) are prevalent, but their significance remains a huge knowledge gap. Answering questions, new and old, such as those discussed here, is needed to understand the ocean's N and C cycles and their responses to environmental change.
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Affiliation(s)
- Jonathan P Zehr
- Ocean Sciences Department, University of California Santa Cruz, Santa Cruz, CA, USA.
| | - Douglas G Capone
- Marine and Environmental Biology Section of Biological Sciences, University of Southern California, Los Angeles, CA, USA
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4
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Vieyra‐Mexicano C, Souza V, Pajares S. Distribution of the N 2 -fixing cyanobacterium Candidatus Atelocyanobacterium thalassa in the Mexican Pacific upwelling system under two contrasting El Niño Southern Oscillation conditions. ENVIRONMENTAL MICROBIOLOGY REPORTS 2024; 16:e13237. [PMID: 38350668 PMCID: PMC10866059 DOI: 10.1111/1758-2229.13237] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Accepted: 01/19/2024] [Indexed: 02/15/2024]
Abstract
The unicellular cyanobacterium Candidatus Atelocyanobacterium thalassa (UCYN-A) is a key diazotroph in the global ocean owing to its high N2 fixation rates and wide distribution in marine environments. Nevertheless, little is known about UCYN-A in oxygen-deficient zones (ODZs), which may be optimal environments for marine diazotrophy. Therefore, the distribution and diversity of UCYN-A were studied in two consecutive years under contrasting phases (La Niña vs. El Niño) of El Niño Southern Oscillation (ENSO) along a transect in the ODZ of the Mexican Pacific upwelling system. Of the three UCYN-A sublineages found, UCYN-A1 and UCYN-A3 were barely detected, whereas UCYN-A2 was dominant in all the stations and showed a wide distribution in both ENSO phases. The presence of UCYN-A was associated with well-oxygenated waters, but it was also found for the first time under suboxic conditions (<20 μM) at the bottom of a shallow coastal station, within the oxygen-poor and nutrient-rich Subsurface Subtropical water mass. This study contributes to the understanding of UCYN-A distribution under different oceanographic conditions associated with ENSO phases in upwelling systems, especially because of the current climate change and increasing deoxygenation in many areas of the world's oceans.
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Affiliation(s)
- Cinthya Vieyra‐Mexicano
- Unidad Académica de Ecología y Biodiversidad Acuática, Institute of Marine Sciences and LimnologyNational Autonomous University of MexicoMexico CityMexico
- Posgrado en Ciencias del Mar y LimnologíaNational Autonomous University of MexicoMexico CityMexico
| | - Valeria Souza
- Departamento de Ecología Evolutiva, Institute of EcologyNational Autonomous University of MexicoMexico CityMexico
| | - Silvia Pajares
- Unidad Académica de Ecología y Biodiversidad Acuática, Institute of Marine Sciences and LimnologyNational Autonomous University of MexicoMexico CityMexico
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5
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Fernández-Juárez V, Hallstrøm S, Pacherres CO, Wang J, Coll-Garcia G, Kühl M, Riemann L. Biofilm formation and cell plasticity drive diazotrophy in an anoxygenic phototrophic bacterium. Appl Environ Microbiol 2023; 89:e0102723. [PMID: 37882569 PMCID: PMC10686084 DOI: 10.1128/aem.01027-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Accepted: 09/14/2023] [Indexed: 10/27/2023] Open
Abstract
IMPORTANCE The contribution of non-cyanobacterial diazotrophs (NCDs) to total N2 fixation in the marine water column is unknown, but their importance is likely constrained by the limited availability of dissolved organic matter and low O2 conditions. Light could support N2 fixation and growth by NCDs, yet no examples from bacterioplankton exist. In this study, we show that the phototrophic NCD, Rhodopseudomonas sp. BAL398, which is a member of the diazotrophic community in the surface waters of the Baltic Sea, can utilize light. Our study highlights the significance of biofilm formation for utilizing light and fixing N2 under oxic conditions and the role of cell plasticity in regulating these processes. Our findings have implications for the general understanding of the ecology and importance of NCDs in marine waters.
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Affiliation(s)
- Víctor Fernández-Juárez
- Marine Biological Section, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Søren Hallstrøm
- Marine Biological Section, Department of Biology, University of Copenhagen, Copenhagen, Denmark
- Bacteria, Parasites and Fungi, Statens Serum Institut, Copenhagen, Denmark
| | - Cesar O. Pacherres
- Marine Biological Section, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Jiaqi Wang
- Marine Biological Section, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Guillem Coll-Garcia
- Microbiology, Biology Department, University of the Balearic Islands, Palma de Mallorca, Spain
- Environmental Microbiology Group, Mediterranean Institute for Advanced Studies (CSIC-UIB), Esporles, Spain
| | - Michael Kühl
- Marine Biological Section, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Lasse Riemann
- Marine Biological Section, Department of Biology, University of Copenhagen, Copenhagen, Denmark
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6
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Turk-Kubo KA, Gradoville MR, Cheung S, Cornejo-Castillo FM, Harding KJ, Morando M, Mills M, Zehr JP. Non-cyanobacterial diazotrophs: global diversity, distribution, ecophysiology, and activity in marine waters. FEMS Microbiol Rev 2023; 47:fuac046. [PMID: 36416813 PMCID: PMC10719068 DOI: 10.1093/femsre/fuac046] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 09/15/2022] [Accepted: 11/17/2022] [Indexed: 12/17/2023] Open
Abstract
Biological dinitrogen (N2) fixation supplies nitrogen to the oceans, supporting primary productivity, and is carried out by some bacteria and archaea referred to as diazotrophs. Cyanobacteria are conventionally considered to be the major contributors to marine N2 fixation, but non-cyanobacterial diazotrophs (NCDs) have been shown to be distributed throughout ocean ecosystems. However, the biogeochemical significance of marine NCDs has not been demonstrated. This review synthesizes multiple datasets, drawing from cultivation-independent molecular techniques and data from extensive oceanic expeditions, to provide a comprehensive view into the diversity, biogeography, ecophysiology, and activity of marine NCDs. A NCD nifH gene catalog was compiled containing sequences from both PCR-based and PCR-free methods, identifying taxa for future studies. NCD abundances from a novel database of NCD nifH-based abundances were colocalized with environmental data, unveiling distinct distributions and environmental drivers of individual taxa. Mechanisms that NCDs may use to fuel and regulate N2 fixation in response to oxygen and fixed nitrogen availability are discussed, based on a metabolic analysis of recently available Tara Oceans expedition data. The integration of multiple datasets provides a new perspective that enhances understanding of the biology, ecology, and biogeography of marine NCDs and provides tools and directions for future research.
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Affiliation(s)
- Kendra A Turk-Kubo
- Ocean Sciences Department, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, United States
| | - Mary R Gradoville
- Ocean Sciences Department, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, United States
- Columbia River Inter-Tribal Fish Commission, Portland, OR, United States
| | - Shunyan Cheung
- Ocean Sciences Department, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, United States
| | - Francisco M Cornejo-Castillo
- Ocean Sciences Department, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, United States
- Department of Marine Biology and Oceanography, Institute of Marine Sciences (ICM-CSIC), Pg. Marítim Barceloneta, 37-49 08003 Barcelona, Spain
| | - Katie J Harding
- Ocean Sciences Department, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, United States
- Marine Biology Research Division, Scripps Institute of Oceanography, 9500 Gilman Drive, La Jolla, CA 92093, United States
| | - Michael Morando
- Ocean Sciences Department, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, United States
| | - Matthew Mills
- Department of Earth System Science, Stanford University, 473 Via Ortega, Stanford, CA 94305, United States
| | - Jonathan P Zehr
- Ocean Sciences Department, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, United States
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7
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Ehrenfels B, Baumann KBL, Niederdorfer R, Mbonde AS, Kimirei IA, Kuhn T, Magyar PM, Odermatt D, Schubert CJ, Bürgmann H, Lehmann MF, Wehrli B, Callbeck CM. Hydrodynamic regimes modulate nitrogen fixation and the mode of diazotrophy in Lake Tanganyika. Nat Commun 2023; 14:6591. [PMID: 37852975 PMCID: PMC10584864 DOI: 10.1038/s41467-023-42391-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 10/10/2023] [Indexed: 10/20/2023] Open
Abstract
The factors that govern the geographical distribution of nitrogen fixation are fundamental to providing accurate nitrogen budgets in aquatic environments. Model-based insights have demonstrated that regional hydrodynamics strongly impact nitrogen fixation. However, the mechanisms establishing this physical-biological coupling have yet to be constrained in field surveys. Here, we examine the distribution of nitrogen fixation in Lake Tanganyika - a model system with well-defined hydrodynamic regimes. We report that nitrogen fixation is five times higher under stratified than under upwelling conditions. Under stratified conditions, the limited resupply of inorganic nitrogen to surface waters, combined with greater light penetration, promotes the activity of bloom-forming photoautotrophic diazotrophs. In contrast, upwelling conditions support predominantly heterotrophic diazotrophs, which are uniquely suited to chemotactic foraging in a more dynamic nutrient landscape. We suggest that these hydrodynamic regimes (stratification versus mixing) play an important role in governing both the rates and the mode of nitrogen fixation.
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Affiliation(s)
- Benedikt Ehrenfels
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department Surface Waters - Research and Management, Kastanienbaum, Switzerland
- ETH Zurich, Institute of Biogeochemistry and Pollutant Dynamics, Zurich, Switzerland
| | - Kathrin B L Baumann
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department Surface Waters - Research and Management, Kastanienbaum, Switzerland
- ETH Zurich, Institute of Biogeochemistry and Pollutant Dynamics, Zurich, Switzerland
| | - Robert Niederdorfer
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department Surface Waters - Research and Management, Kastanienbaum, Switzerland
| | | | - Ismael A Kimirei
- TAFIRI, Tanzania Fisheries Research Institute, Kigoma, Tanzania
- TAFIRI, Tanzania Fisheries Research Institute, Dar es Salaam, Tanzania
| | - Thomas Kuhn
- University of Basel, Department of Environmental Sciences, Basel, Switzerland
| | - Paul M Magyar
- University of Basel, Department of Environmental Sciences, Basel, Switzerland
| | - Daniel Odermatt
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department Surface Waters - Research and Management, Kastanienbaum, Switzerland
| | - Carsten J Schubert
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department Surface Waters - Research and Management, Kastanienbaum, Switzerland
- ETH Zurich, Institute of Biogeochemistry and Pollutant Dynamics, Zurich, Switzerland
| | - Helmut Bürgmann
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department Surface Waters - Research and Management, Kastanienbaum, Switzerland
| | - Moritz F Lehmann
- University of Basel, Department of Environmental Sciences, Basel, Switzerland
| | - Bernhard Wehrli
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department Surface Waters - Research and Management, Kastanienbaum, Switzerland
- ETH Zurich, Institute of Biogeochemistry and Pollutant Dynamics, Zurich, Switzerland
| | - Cameron M Callbeck
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department Surface Waters - Research and Management, Kastanienbaum, Switzerland.
- University of Basel, Department of Environmental Sciences, Basel, Switzerland.
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8
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Dithugoe CD, Bezuidt OKI, Cavan EL, Froneman WP, Thomalla SJ, Makhalanyane TP. Bacteria and Archaea Regulate Particulate Organic Matter Export in Suspended and Sinking Marine Particle Fractions. mSphere 2023:e0042022. [PMID: 37093039 DOI: 10.1128/msphere.00420-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2023] Open
Abstract
The biological carbon pump (BCP) in the Southern Ocean is driven by phytoplankton productivity and is a significant organic matter sink. However, the role of particle-attached (PA) and free-living (FL) prokaryotes (bacteria and archaea) and their diversity in influencing the efficiency of the BCP is still unclear. To investigate this, we analyzed the metagenomes linked to suspended and sinking marine particles from the Sub-Antarctic Southern Ocean Time Series (SOTS) by deploying a Marine Snow Catcher (MSC), obtaining suspended and sinking particulate material, determining organic carbon and nitrogen flux, and constructing metagenome-assembled genomes (MAGs). The suspended and sinking particle-pools were dominated by bacteria with the potential to degrade organic carbon. Bacterial communities associated with the sinking fraction had more genes related to the degradation of complex organic carbon than those in the suspended fraction. Archaea had the potential to drive nitrogen metabolism via nitrite and ammonia oxidation, altering organic nitrogen concentration. The data revealed several pathways for chemoautotrophy and the secretion of recalcitrant dissolved organic carbon (RDOC) from CO2, with bacteria and archaea potentially sequestering particulate organic matter (POM) via the production of RDOC. These findings provide insights into the diversity and function of prokaryotes in suspended and sinking particles and their role in organic carbon/nitrogen export in the Southern Ocean. IMPORTANCE The biological carbon pump is crucial for the export of particulate organic matter in the ocean. Recent studies on marine microbes have shown the profound influence of bacteria and archaea as regulators of particulate organic matter export. Yet, despite the importance of the Southern Ocean as a carbon sink, we lack comparable insights regarding microbial contributions. This study provides the first insights regarding prokaryotic contributions to particulate organic matter export in the Southern Ocean. We reveal evidence that prokaryotic communities in suspended and sinking particle fractions harbor widespread genomic potential for mediating particulate organic matter export. The results substantially enhance our understanding of the role played by microorganisms in regulating particulate organic matter export in suspended and sinking marine fractions in the Southern Ocean.
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Affiliation(s)
- Choaro D Dithugoe
- Southern Ocean Carbon-Climate Observatory (SOCCO), Council of Scientific & Industrial Research (CSIR), Rosebank, Cape Town, South Africa
- SARChI Chair: Marine Ecosystems and Resources, Department of Entomology & Zoology, Rhodes University (RU), Makhanda, Eastern Cape, South Africa
- SARChI Chair: Marine Microbiomics, microbiome@UP, Department of Biochemistry, Genetics and Microbiology, University of Pretoria (UP), Hatfield, Pretoria, South Africa
| | - Oliver K I Bezuidt
- SARChI Chair: Marine Microbiomics, microbiome@UP, Department of Biochemistry, Genetics and Microbiology, University of Pretoria (UP), Hatfield, Pretoria, South Africa
| | - Emma L Cavan
- Imperial College London, Berks, Silwood Park, Berkshire, United Kingdom
| | - William P Froneman
- SARChI Chair: Marine Ecosystems and Resources, Department of Entomology & Zoology, Rhodes University (RU), Makhanda, Eastern Cape, South Africa
| | - Sandy J Thomalla
- Southern Ocean Carbon-Climate Observatory (SOCCO), Council of Scientific & Industrial Research (CSIR), Rosebank, Cape Town, South Africa
| | - Thulani P Makhalanyane
- SARChI Chair: Marine Microbiomics, microbiome@UP, Department of Biochemistry, Genetics and Microbiology, University of Pretoria (UP), Hatfield, Pretoria, South Africa
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9
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Joublin-Delavat A, Touahri K, Crétin P, Morot A, Rodrigues S, Jesus B, Trigodet F, Delavat F. Genetic and physiological insights into the diazotrophic activity of a non-cyanobacterial marine diazotroph. Environ Microbiol 2022; 24:6510-6523. [PMID: 36302093 PMCID: PMC10099842 DOI: 10.1111/1462-2920.16261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Accepted: 10/21/2022] [Indexed: 01/12/2023]
Abstract
Nitrogen (N2 ) fixation, or diazotrophy, supports a large part of primary production in oceans. Culture-independent approaches highlighted the presence in abundance of marine non-cyanobacterial diazotrophs (NCD), but their ecophysiology remains elusive, mostly because of the low number of isolated NCD and because of the lack of available genetic tools for these isolates. Here, a dual genetic and functional approach allowed unveiling the ecophysiology of a marine NCD affiliated to the species Vibrio diazotrophicus. Physiological characterization of the first marine NCD mutant obtained so far was performed using a soft-gellan assay, demonstrating that a ΔnifH mutant is not able to grow in nitrogen-free media. Furthermore, we demonstrated that V. diazotrophicus produces a thick biofilm under diazotrophic conditions, suggesting biofilm production as an adaptive response of this NCD to cope with the inhibition of nitrogen fixation by molecular oxygen. Finally, the genomic signature of V. diazotrophicus is essentially absent from metagenomic data of Tara Ocean expeditions, despite having been isolated from various marine environments. We think that the genetically tractable V. diazotrophicus strain used in this study may serve as an ideal model to study the ecophysiology of these overlooked procaryotic group.
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Affiliation(s)
| | - Katia Touahri
- Nantes Université, CNRS, US2B, UMR6286, Nantes, France.,Laboratoire Chimie et Biochimie de Molécules Bioactives, Université de Strasbourg/CNRS, UMR7177, Strasbourg, France
| | | | - Amandine Morot
- Univ Brest, CNRS, IRD, Ifremer, LEMAR, Plouzané, France.,Université de Bretagne-Sud, UR3884, LBCM, IUEM, Lorient, France
| | | | - Bruno Jesus
- Nantes Université, RSBE2 ISOMer, UR2160, Nantes, France
| | - Florian Trigodet
- Department of Medicine, The University of Chicago, Chicago, Illinois, USA
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10
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Gradoville MR, Dugenne M, Hynes AM, Zehr JP, White AE. Empirical relationship between nifH gene abundance and diazotroph cell concentration in the North Pacific Subtropical Gyre. JOURNAL OF PHYCOLOGY 2022; 58:829-833. [PMID: 36266252 DOI: 10.1111/jpy.13289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Accepted: 09/24/2022] [Indexed: 06/16/2023]
Abstract
Cyanobacterial N2 -fixing microorganisms (diazotrophs) play a critical role in nitrogen and carbon cycling in the oceans; hence, accurate measurements of diazotroph abundance are imperative for understanding ocean biogeochemistry. Marine diazotroph abundances are often assessed using qPCR of the nifH gene, a sensitive, taxa-specific, and time/cost-efficient method. However, the validity of nifH abundance as a proxy for cell concentration has recently been questioned. Here, we compare nifH gene abundances to cell counts for four diazotroph taxa (Trichodesmium, Crocosphaera, Richelia, and Calothrix) on two cruises to the North Pacific Subtropical Gyre, one of the largest habitats for marine diazotrophs. nifH:cell relationships were strong and significant for Crocosphaera, Richelia, and Calothrix (nifH:cell 1.51-2.58; R2 = 0.89-0.96) but were not significant for Trichodesmium, despite previous studies reporting significant nifH:cell relationships for this organism. Limited available data suggest that empirical nifH:cell can vary among studies but that relationships are usually significantly linear and >1:1. Our study indicates that nifH gene abundance, while not a direct measure of cells, is a useful quantitative proxy for diazotroph abundance.
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Affiliation(s)
- Mary R Gradoville
- Ocean Sciences Department, University of California Santa Cruz, Santa Cruz, California, 95064, USA
| | - Mathilde Dugenne
- Department of Oceanography, University of Hawai'i at Mānoa, Honolulu, Hawaii, 96822, USA
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education, University of Hawai'i at Mānoa, Honolulu, Hawaii, 96822, USA
| | - Annette M Hynes
- School of Oceanography, University of Washington, Seattle, Washington, 98195, USA
| | - Jonathan P Zehr
- Ocean Sciences Department, University of California Santa Cruz, Santa Cruz, California, 95064, USA
| | - Angelicque E White
- Department of Oceanography, University of Hawai'i at Mānoa, Honolulu, Hawaii, 96822, USA
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education, University of Hawai'i at Mānoa, Honolulu, Hawaii, 96822, USA
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11
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Harding KJ, Turk-Kubo KA, Mak EWK, Weber PK, Mayali X, Zehr JP. Cell-specific measurements show nitrogen fixation by particle-attached putative non-cyanobacterial diazotrophs in the North Pacific Subtropical Gyre. Nat Commun 2022; 13:6979. [PMID: 36379938 PMCID: PMC9666432 DOI: 10.1038/s41467-022-34585-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Accepted: 10/31/2022] [Indexed: 11/16/2022] Open
Abstract
Biological nitrogen fixation is a major important source of nitrogen for low-nutrient surface oceanic waters. Nitrogen-fixing (diazotrophic) cyanobacteria are believed to be the primary contributors to this process, but the contribution of non-cyanobacterial diazotrophic organisms in oxygenated surface water, while hypothesized to be important, has yet to be demonstrated. In this study, we used simultaneous 15N-dinitrogen and 13C-bicarbonate incubations combined with nanoscale secondary ion mass spectrometry analysis to screen tens of thousands of mostly particle-associated, cell-like regions of interest collected from the North Pacific Subtropical Gyre. These dual isotope incubations allow us to distinguish between non-cyanobacterial and cyanobacterial nitrogen-fixing microorganisms and to measure putative cell-specific nitrogen fixation rates. With this approach, we detect nitrogen fixation by putative non-cyanobacterial diazotrophs in the oxygenated surface ocean, which are associated with organic-rich particles (<210 µm size fraction) at two out of seven locations sampled. When present, up to 4.1% of the analyzed particles contain at least one active putative non-cyanobacterial diazotroph. The putative non-cyanobacterial diazotroph nitrogen fixation rates (0.76 ± 1.60 fmol N cell-1 d-1) suggest that these organisms are capable of fixing dinitrogen in oxygenated surface water, at least when attached to particles, and may contribute to oceanic nitrogen fixation.
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Affiliation(s)
- Katie J Harding
- Department of Ocean Sciences, University of California, Santa Cruz, CA, USA
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, USA
| | - Kendra A Turk-Kubo
- Department of Ocean Sciences, University of California, Santa Cruz, CA, USA
| | | | - Peter K Weber
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, USA
| | - Xavier Mayali
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, USA.
| | - Jonathan P Zehr
- Department of Ocean Sciences, University of California, Santa Cruz, CA, USA.
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12
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Phosphate limitation intensifies negative effects of ocean acidification on globally important nitrogen fixing cyanobacterium. Nat Commun 2022; 13:6730. [PMID: 36344528 PMCID: PMC9640675 DOI: 10.1038/s41467-022-34586-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 10/28/2022] [Indexed: 11/11/2022] Open
Abstract
Growth of the prominent nitrogen-fixing cyanobacterium Trichodesmium is often limited by phosphorus availability in the ocean. How nitrogen fixation by phosphorus-limited Trichodesmium may respond to ocean acidification remains poorly understood. Here, we use phosphate-limited chemostat experiments to show that acidification enhanced phosphorus demands and decreased phosphorus-specific nitrogen fixation rates in Trichodesmium. The increased phosphorus requirements were attributed primarily to elevated cellular polyphosphate contents, likely for maintaining cytosolic pH homeostasis in response to acidification. Alongside the accumulation of polyphosphate, decreased NADP(H):NAD(H) ratios and impaired chlorophyll synthesis and energy production were observed under acidified conditions. Consequently, the negative effects of acidification were amplified compared to those demonstrated previously under phosphorus sufficiency. Estimating the potential implications of this finding, using outputs from the Community Earth System Model, predicts that acidification and dissolved inorganic and organic phosphorus stress could synergistically cause an appreciable decrease in global Trichodesmium nitrogen fixation by 2100.
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13
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Hallstrøm S, Raina JB, Ostrowski M, Parks DH, Tyson GW, Hugenholtz P, Stocker R, Seymour JR, Riemann L. Chemotaxis may assist marine heterotrophic bacterial diazotrophs to find microzones suitable for N 2 fixation in the pelagic ocean. THE ISME JOURNAL 2022; 16:2525-2534. [PMID: 35915168 PMCID: PMC9561647 DOI: 10.1038/s41396-022-01299-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 07/18/2022] [Accepted: 07/20/2022] [Indexed: 06/05/2023]
Abstract
Heterotrophic bacterial diazotrophs (HBDs) are ubiquitous in the pelagic ocean, where they have been predicted to carry out the anaerobic process of nitrogen fixation within low-oxygen microenvironments associated with marine pelagic particles. However, the mechanisms enabling particle colonization by HBDs are unknown. We hypothesized that HBDs use chemotaxis to locate and colonize suitable microenvironments, and showed that a cultivated marine HBD is chemotactic toward amino acids and phytoplankton-derived DOM. Using an in situ chemotaxis assay, we also discovered that diverse HBDs at a coastal site are motile and chemotactic toward DOM from various phytoplankton taxa and, indeed, that the proportion of diazotrophs was up to seven times higher among the motile fraction of the bacterial community compared to the bulk seawater community. Finally, three of four HBD isolates and 16 of 17 HBD metagenome assembled genomes, recovered from major ocean basins and locations along the Australian coast, each encoded >85% of proteins affiliated with the bacterial chemotaxis pathway. These results document the widespread capacity for chemotaxis in diverse and globally relevant marine HBDs. We suggest that HBDs could use chemotaxis to seek out and colonize low-oxygen microenvironments suitable for nitrogen fixation, such as those formed on marine particles. Chemotaxis in HBDs could therefore affect marine nitrogen and carbon biogeochemistry by facilitating nitrogen fixation within otherwise oxic waters, while also altering particle degradation and the efficiency of the biological pump.
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Affiliation(s)
- Søren Hallstrøm
- Marine Biological Section, Department of Biology, University of Copenhagen, Helsingør, Denmark
| | - Jean-Baptiste Raina
- Climate Change Cluster, Faculty of Science, University of Technology Sydney, Sydney, NSW, Australia
| | - Martin Ostrowski
- Climate Change Cluster, Faculty of Science, University of Technology Sydney, Sydney, NSW, Australia
| | - Donovan H Parks
- Australian Centre for Ecogenomics, School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, QLD, Australia
| | - Gene W Tyson
- Centre for Microbiome Research, School of Biomedical Science, Translational Research Institute, Queensland University of Technology, Woolloongabba, QLD, Australia
| | - Philip Hugenholtz
- Australian Centre for Ecogenomics, School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, QLD, Australia
| | - Roman Stocker
- Institute of Environmental Engineering, Department of Civil, Environmental and Geomatic Engineering, ETH Zurich, Zurich, Switzerland
| | - Justin R Seymour
- Climate Change Cluster, Faculty of Science, University of Technology Sydney, Sydney, NSW, Australia
| | - Lasse Riemann
- Marine Biological Section, Department of Biology, University of Copenhagen, Helsingør, Denmark.
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14
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Alcamán-Arias ME, Cifuentes-Anticevic J, Castillo-Inaipil W, Farías L, Sanhueza C, Fernández-Gómez B, Verdugo J, Abarzua L, Ridley C, Tamayo-Leiva J, Díez B. Dark Diazotrophy during the Late Summer in Surface Waters of Chile Bay, West Antarctic Peninsula. Microorganisms 2022; 10:microorganisms10061140. [PMID: 35744658 PMCID: PMC9227844 DOI: 10.3390/microorganisms10061140] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 05/28/2022] [Accepted: 05/29/2022] [Indexed: 11/16/2022] Open
Abstract
Although crucial for the addition of new nitrogen in marine ecosystems, dinitrogen (N2) fixation remains an understudied process, especially under dark conditions and in polar coastal areas, such as the West Antarctic Peninsula (WAP). New measurements of light and dark N2 fixation rates in parallel with carbon (C) fixation rates, as well as analysis of the genetic marker nifH for diazotrophic organisms, were conducted during the late summer in the coastal waters of Chile Bay, South Shetland Islands, WAP. During six late summers (February 2013 to 2019), Chile Bay was characterized by high NO3− concentrations (~20 µM) and an NH4+ content that remained stable near 0.5 µM. The N:P ratio was approximately 14.1, thus close to that of the Redfield ratio (16:1). The presence of Cluster I and Cluster III nifH gene sequences closely related to Alpha-, Delta- and, to a lesser extent, Gammaproteobacteria, suggests that chemosynthetic and heterotrophic bacteria are primarily responsible for N2 fixation in the bay. Photosynthetic carbon assimilation ranged from 51.18 to 1471 nmol C L−1 d−1, while dark chemosynthesis ranged from 9.24 to 805 nmol C L−1 d−1. N2 fixation rates were higher under dark conditions (up to 45.40 nmol N L−1 d−1) than under light conditions (up to 7.70 nmol N L−1 d−1), possibly contributing more than 37% to new nitrogen-based production (≥2.5 g N m−2 y−1). Of all the environmental factors measured, only PO43- exhibited a significant correlation with C and N2 rates, being negatively correlated (p < 0.05) with dark chemosynthesis and N2 fixation under the light condition, revealing the importance of the N:P ratio for these processes in Chile Bay. This significant contribution of N2 fixation expands the ubiquity and biological potential of these marine chemosynthetic diazotrophs. As such, this process should be considered along with the entire N cycle when further reviewing highly productive Antarctic coastal waters and the diazotrophic potential of the global marine ecosystem.
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Affiliation(s)
- María E. Alcamán-Arias
- Departamento de Oceanografía, Universidad de Concepción, Concepción 4030000, Chile; (M.E.A.-A.); (L.F.); (L.A.)
- Center for Climate and Resilience Research (CR)2, Universidad de Chile, Blanco Encalada 2002, Santiago 8320000, Chile; (C.R.); (J.T.-L.)
- Escuela de Medicina, Universidad Espíritu Santo, Guayaquil 0901952, Ecuador
| | - Jerónimo Cifuentes-Anticevic
- Departamento de Genética Molecular y Microbiología, Pontificia Universidad Católica de Chile, Santiago 8331150, Chile; (J.C.-A.); (W.C.-I.); (C.S.); (B.F.-G.)
| | - Wilson Castillo-Inaipil
- Departamento de Genética Molecular y Microbiología, Pontificia Universidad Católica de Chile, Santiago 8331150, Chile; (J.C.-A.); (W.C.-I.); (C.S.); (B.F.-G.)
| | - Laura Farías
- Departamento de Oceanografía, Universidad de Concepción, Concepción 4030000, Chile; (M.E.A.-A.); (L.F.); (L.A.)
- Center for Climate and Resilience Research (CR)2, Universidad de Chile, Blanco Encalada 2002, Santiago 8320000, Chile; (C.R.); (J.T.-L.)
| | - Cynthia Sanhueza
- Departamento de Genética Molecular y Microbiología, Pontificia Universidad Católica de Chile, Santiago 8331150, Chile; (J.C.-A.); (W.C.-I.); (C.S.); (B.F.-G.)
| | - Beatriz Fernández-Gómez
- Departamento de Genética Molecular y Microbiología, Pontificia Universidad Católica de Chile, Santiago 8331150, Chile; (J.C.-A.); (W.C.-I.); (C.S.); (B.F.-G.)
- Instituto de Oceanografía y Cambio Global (IOCAG), Universidad de Las Palmas de Gran Canaria (ULPGC), 35001 Las Palmas, Spain
| | - Josefa Verdugo
- Alfred-Wegener-Institute, Helmholtz Centre for Polar and Marine Research, 27570 Bremerhaven, Germany;
| | - Leslie Abarzua
- Departamento de Oceanografía, Universidad de Concepción, Concepción 4030000, Chile; (M.E.A.-A.); (L.F.); (L.A.)
| | - Christina Ridley
- Center for Climate and Resilience Research (CR)2, Universidad de Chile, Blanco Encalada 2002, Santiago 8320000, Chile; (C.R.); (J.T.-L.)
- Departamento de Genética Molecular y Microbiología, Pontificia Universidad Católica de Chile, Santiago 8331150, Chile; (J.C.-A.); (W.C.-I.); (C.S.); (B.F.-G.)
| | - Javier Tamayo-Leiva
- Center for Climate and Resilience Research (CR)2, Universidad de Chile, Blanco Encalada 2002, Santiago 8320000, Chile; (C.R.); (J.T.-L.)
- Departamento de Genética Molecular y Microbiología, Pontificia Universidad Católica de Chile, Santiago 8331150, Chile; (J.C.-A.); (W.C.-I.); (C.S.); (B.F.-G.)
- Center for Genome Regulation (CRG), Universidad de Chile, Blanco Encalada 2085, Santiago 8320000, Chile
| | - Beatriz Díez
- Center for Climate and Resilience Research (CR)2, Universidad de Chile, Blanco Encalada 2002, Santiago 8320000, Chile; (C.R.); (J.T.-L.)
- Departamento de Genética Molecular y Microbiología, Pontificia Universidad Católica de Chile, Santiago 8331150, Chile; (J.C.-A.); (W.C.-I.); (C.S.); (B.F.-G.)
- Center for Genome Regulation (CRG), Universidad de Chile, Blanco Encalada 2085, Santiago 8320000, Chile
- Correspondence:
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15
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Riemann L, Rahav E, Passow U, Grossart HP, de Beer D, Klawonn I, Eichner M, Benavides M, Bar-Zeev E. Planktonic Aggregates as Hotspots for Heterotrophic Diazotrophy: The Plot Thickens. Front Microbiol 2022; 13:875050. [PMID: 35464923 PMCID: PMC9019601 DOI: 10.3389/fmicb.2022.875050] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2022] [Accepted: 03/11/2022] [Indexed: 11/26/2022] Open
Abstract
Biological dinitrogen (N2) fixation is performed solely by specialized bacteria and archaea termed diazotrophs, introducing new reactive nitrogen into aquatic environments. Conventionally, phototrophic cyanobacteria are considered the major diazotrophs in aquatic environments. However, accumulating evidence indicates that diverse non-cyanobacterial diazotrophs (NCDs) inhabit a wide range of aquatic ecosystems, including temperate and polar latitudes, coastal environments and the deep ocean. NCDs are thus suspected to impact global nitrogen cycling decisively, yet their ecological and quantitative importance remain unknown. Here we review recent molecular and biogeochemical evidence demonstrating that pelagic NCDs inhabit and thrive especially on aggregates in diverse aquatic ecosystems. Aggregates are characterized by reduced-oxygen microzones, high C:N ratio (above Redfield) and high availability of labile carbon as compared to the ambient water. We argue that planktonic aggregates are important loci for energetically-expensive N2 fixation by NCDs and propose a conceptual framework for aggregate-associated N2 fixation. Future studies on aggregate-associated diazotrophy, using novel methodological approaches, are encouraged to address the ecological relevance of NCDs for nitrogen cycling in aquatic environments.
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Affiliation(s)
- Lasse Riemann
- Marine Biology Section, University of Copenhagen, Helsingør, Denmark
| | - Eyal Rahav
- Israel Oceanographic and Limnological Research, Haifa, Israel
| | - Uta Passow
- Ocean Science Centre, Memorial University of Newfoundland, St. John's, NL, Canada
| | - Hans-Peter Grossart
- Institute for Biochemistry and Biology, Potsdam University, Potsdam, Germany.,Department of Plankton and Microbial Ecology, Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Stechlin, Germany
| | - Dirk de Beer
- Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Isabell Klawonn
- Department of Biological Oceanography, Leibniz Institute for Baltic Sea Research, Rostock, Germany
| | - Meri Eichner
- Institute of Microbiology CAS, Centre ALGATECH, Třeboň, Czechia
| | - Mar Benavides
- Aix Marseille Univ, Université de Toulon, CNRS, IRD, MIO, Marseille, France.,Turing Center for Living Systems, Aix-Marseille University, Marseille, France
| | - Edo Bar-Zeev
- The Jacob Blaustein Institutes for Desert Research, Zuckerberg Institute for Water Research (ZIWR), Ben-Gurion University of the Negev, Be'er Sheva, Israel
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16
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Geisler E, Rahav E, Bar-Zeev E. Contribution of Heterotrophic Diazotrophs to N2 Fixation in a Eutrophic River: Free-Living vs. Aggregate-Associated. Front Microbiol 2022; 13:779820. [PMID: 35237246 PMCID: PMC8882987 DOI: 10.3389/fmicb.2022.779820] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2021] [Accepted: 01/19/2022] [Indexed: 12/19/2022] Open
Abstract
Recent studies have indicated that heterotrophic diazotrophs are highly diverse and fix N2 in aquatic environments with potentially adverse conditions for diazotrophy, such as oxic and rich in total nitrogen. In this study, we compared the activity and diversity of heterotrophic diazotrophs associated with aggregates (>12 μm) to free-living cells in the eutrophic Qishon River during the winter and summer seasons. Overall, measured heterotrophic N2 fixation rates in the Qishon River ranged between 2.6–3.5 nmol N L–1 d–1. Heterotrophic N2 fixation was mainly associated with aggregates in the summer samples (74 ± 24%), whereas during the winter the bulk diazotrophic activity was mostly ascribed to the free-living fraction (90 ± 6%). In addition, immunolabeled micrographs indicated the presence of aggregate-associated heterotrophic diazotrophs in both seasons, while phototrophic diazotrophs were also captured during the winter. The richness of free-living and aggregate-associated heterotrophic diazotrophs were overall similar, yet the evenness of the later was significantly smaller, suggesting that few of the species gained advantage from particle lifestyle. The differences in the activity, micro-localization and diversity of the diazotrophic community were mostly attributed to spatiotemporal changes in the ambient C:N ratios (total organic carbon, TOC: total nitrogen) and the TOC concentrations. Taken together, our results shed new light on the contribution of heterotrophic diazotroph associated with aggregates to total heterotrophic N2 fixation in oxic, highly eutrophic aquatic environments.
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Affiliation(s)
- Eyal Geisler
- Zuckerberg Institute for Water Research, The Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sde Boker, Israel
- Israel Oceanographic and Limnological Research, National Institute of Oceanography, Haifa, Israel
| | - Eyal Rahav
- Israel Oceanographic and Limnological Research, National Institute of Oceanography, Haifa, Israel
- *Correspondence: Eyal Rahav,
| | - Edo Bar-Zeev
- Zuckerberg Institute for Water Research, The Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sde Boker, Israel
- Edo Bar-Zeev,
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17
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The marine nitrogen cycle: new developments and global change. Nat Rev Microbiol 2022; 20:401-414. [PMID: 35132241 DOI: 10.1038/s41579-022-00687-z] [Citation(s) in RCA: 51] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/07/2022] [Indexed: 12/25/2022]
Abstract
The ocean is home to a diverse and metabolically versatile microbial community that performs the complex biochemical transformations that drive the nitrogen cycle, including nitrogen fixation, assimilation, nitrification and nitrogen loss processes. In this Review, we discuss the wealth of new ocean nitrogen cycle research in disciplines from metaproteomics to global biogeochemical modelling and in environments from productive estuaries to the abyssal deep sea. Influential recent discoveries include new microbial functional groups, novel metabolic pathways, original conceptual perspectives and ground-breaking analytical capabilities. These emerging research directions are already contributing to urgent efforts to address the primary challenge facing marine microbiologists today: the unprecedented onslaught of anthropogenic environmental change on marine ecosystems. Ocean warming, acidification, nutrient enrichment and seawater stratification have major effects on the microbial nitrogen cycle, but widespread ocean deoxygenation is perhaps the most consequential for the microorganisms involved in both aerobic and anaerobic nitrogen transformation pathways. In turn, these changes feed back to the global cycles of greenhouse gases such as carbon dioxide and nitrous oxide. At a time when our species casts a lengthening shadow across all marine ecosystems, timely new advances offer us unique opportunities to understand and better predict human impacts on nitrogen biogeochemistry in the changing ocean of the Anthropocene.
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18
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Marcarelli AM, Fulweiler RW, Scott JT. Nitrogen fixation: a poorly understood process along the freshwater-marine continuum. LIMNOLOGY AND OCEANOGRAPHY LETTERS 2022; 7:1-10. [PMID: 35531372 PMCID: PMC9075158 DOI: 10.1002/lol2.10220] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Accepted: 10/08/2021] [Indexed: 06/14/2023]
Abstract
Although N2 fixation is a major component of the global N cycle and has been extensively studied in open-ocean and terrestrial ecosystems, rates and ecological dynamics remain virtually unknown for the inland and coastal aquatic ecosystems (lakes, wetlands, rivers, streams, estuaries) that connect terrestrial and marine biomes. This is due to the diversity of these habitats, as well as the traditional paradigm that N2 fixation rates were low to nonexistent, and therefore not important, in these ecosystems. We identify three major research themes to advance understanding of aquatic N2 fixation: 1) the biological diversity of diazotrophs and variability of N2 fixation rates, 2) the ecological stoichiometry of N2 fixation, and 3) the upscaling of N2 fixation rates from genes to ecosystems. Coordinating research across these areas will advance limnology and oceanography by fully integrating N2 fixation into ecological dynamics of aquatic ecosystems from local to global scales.
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Affiliation(s)
- Amy M. Marcarelli
- Department of Biological Sciences, Michigan Technological University
| | - Robinson W. Fulweiler
- Department of Earth and Environment, Boston University
- Department of Biology, Boston University
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19
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Delmont TO, Pierella Karlusich JJ, Veseli I, Fuessel J, Eren AM, Foster RA, Bowler C, Wincker P, Pelletier E. Heterotrophic bacterial diazotrophs are more abundant than their cyanobacterial counterparts in metagenomes covering most of the sunlit ocean. ISME JOURNAL 2021; 16:927-936. [PMID: 34697433 DOI: 10.1038/s41396-021-01135-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 09/24/2021] [Accepted: 09/29/2021] [Indexed: 12/30/2022]
Abstract
Biological nitrogen fixation contributes significantly to marine primary productivity. The current view depicts few cyanobacterial diazotrophs as the main marine nitrogen fixers. Here, we used 891 Tara Oceans metagenomes derived from surface waters of five oceans and two seas to generate a manually curated genomic database corresponding to free-living, filamentous, colony-forming, particle-attached, and symbiotic bacterial and archaeal populations. The database provides the genomic content of eight cyanobacterial diazotrophs including a newly discovered population related to known heterocystous symbionts of diatoms, as well as 40 heterotrophic bacterial diazotrophs that considerably expand the known diversity of abundant marine nitrogen fixers. These 48 populations encapsulate 92% of metagenomic signal for known nifH genes in the sunlit ocean, suggesting that the genomic characterization of the most abundant marine diazotrophs may be nearing completion. Newly identified heterotrophic bacterial diazotrophs are widespread, express their nifH genes in situ, and also occur in large planktonic size fractions where they might form aggregates that provide the low-oxygen microenvironments required for nitrogen fixation. Critically, we found heterotrophic bacterial diazotrophs to be more abundant than cyanobacterial diazotrophs in most metagenomes from the open oceans and seas, emphasizing the importance of a wide range of heterotrophic populations in the marine nitrogen balance.
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Affiliation(s)
- Tom O Delmont
- Génomique Métabolique, Genoscope, Institut François Jacob, CEA, CNRS, Univ Evry, Université Paris-Saclay, 91057, Evry, France. .,Research Federation for the study of Global Ocean systems ecology and evolution, FR2022/Tara GOsee, Paris, France.
| | - Juan José Pierella Karlusich
- Research Federation for the study of Global Ocean systems ecology and evolution, FR2022/Tara GOsee, Paris, France.,Institut de Biologie de l'ENS (IBENS), Département de biologie, École normale supérieure, CNRS, INSERM, Université PSL, 75005, Paris, France
| | - Iva Veseli
- Graduate Program in Biophysical Sciences, University of Chicago, Chicago, IL, 60637, USA
| | - Jessika Fuessel
- Department of Medicine, University of Chicago, Chicago, IL, 60637, USA
| | - A Murat Eren
- Department of Medicine, University of Chicago, Chicago, IL, 60637, USA.,Bay Paul Center, Marine Biological Laboratory, Woods Hole, MA, 02543, USA
| | - Rachel A Foster
- Department of Ecology, Environment and Plant Sciences, Stockholm University Stockholm, Stockholm, 106 91, Sweden
| | - Chris Bowler
- Research Federation for the study of Global Ocean systems ecology and evolution, FR2022/Tara GOsee, Paris, France.,Institut de Biologie de l'ENS (IBENS), Département de biologie, École normale supérieure, CNRS, INSERM, Université PSL, 75005, Paris, France
| | - Patrick Wincker
- Génomique Métabolique, Genoscope, Institut François Jacob, CEA, CNRS, Univ Evry, Université Paris-Saclay, 91057, Evry, France.,Research Federation for the study of Global Ocean systems ecology and evolution, FR2022/Tara GOsee, Paris, France
| | - Eric Pelletier
- Génomique Métabolique, Genoscope, Institut François Jacob, CEA, CNRS, Univ Evry, Université Paris-Saclay, 91057, Evry, France.,Research Federation for the study of Global Ocean systems ecology and evolution, FR2022/Tara GOsee, Paris, France
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20
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Rabouille S, Randall B, Talec A, Raimbault P, Blasco T, Latifi A, Oschlies A. Independence of a Marine Unicellular Diazotroph to the Presence of NO 3. Microorganisms 2021; 9:microorganisms9102073. [PMID: 34683393 PMCID: PMC8540418 DOI: 10.3390/microorganisms9102073] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 09/23/2021] [Accepted: 09/28/2021] [Indexed: 11/23/2022] Open
Abstract
Marine nitrogen (N2) fixation was historically considered to be absent or reduced in nitrate (NO3−) rich environments. This is commonly attributed to the lower energetic cost of NO3− uptake compared to diazotrophy in oxic environments. This paradigm often contributes to making inferences about diazotroph distribution and activity in the ocean, and is also often used in biogeochemical ocean models. To assess the general validity of this paradigm beyond the traditionally used model organism Trichodesmium spp., we grew cultures of the unicellular cyanobacterium Crocosphaera watsonii WH8501 long term in medium containing replete concentrations of NO3−. NO3− uptake was measured in comparison to N2 fixation to assess the cultures’ nitrogen source preferences. We further measured culture growth rate, cell stoichiometry, and carbon fixation rate to determine if the presence of NO3− had any effect on cell metabolism. We found that uptake of NO3− by this strain of Crocosphaera was minimal in comparison to other N sources (~2–4% of total uptake). Furthermore, availability of NO3− did not statistically alter N2 fixation rate nor any aspect of cell physiology or metabolism measured (cellular growth rate, cell stoichiometry, cell size, nitrogen fixation rate, nitrogenase activity) in comparison to a NO3− free control culture. These results demonstrate the capability of a marine diazotroph to fix nitrogen and grow independently of NO3−. This lack of sensitivity of diazotrophy to NO3− suggests that assumptions often made about, and model formulations of, N2 fixation should be reconsidered.
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Affiliation(s)
- Sophie Rabouille
- Laboratoire d’Océanographie Microbienne (LOMIC), CNRS, Sorbonne Université, F-66650 Banyuls-sur-Mer, France
- Laboratoire d’Océanographie de Villefranche (LOV), CNRS, Sorbonne Université, F-06230 Villefranche-sur-Mer, France; (B.R.); (A.T.); (T.B.)
- Correspondence:
| | - Benjamin Randall
- Laboratoire d’Océanographie de Villefranche (LOV), CNRS, Sorbonne Université, F-06230 Villefranche-sur-Mer, France; (B.R.); (A.T.); (T.B.)
| | - Amélie Talec
- Laboratoire d’Océanographie de Villefranche (LOV), CNRS, Sorbonne Université, F-06230 Villefranche-sur-Mer, France; (B.R.); (A.T.); (T.B.)
| | - Patrick Raimbault
- Aix Marseille Université, CNRS/INSU, Université de Toulon, IRD, Mediterranean Institute of Oceanography (MIO) UM 110, 13288 Marseille, France;
| | - Thierry Blasco
- Laboratoire d’Océanographie de Villefranche (LOV), CNRS, Sorbonne Université, F-06230 Villefranche-sur-Mer, France; (B.R.); (A.T.); (T.B.)
| | - Amel Latifi
- Laboratoire de Chimie Bactérienne (LCB), Aix Marseille Université, CNRS, 13284 Marseille, France;
| | - Andreas Oschlies
- GEOMAR Helmholtz Centre for Ocean Research Kiel, 24105 Kiel, Germany;
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21
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Landolfi A, Prowe AEF, Pahlow M, Somes CJ, Chien CT, Schartau M, Koeve W, Oschlies A. Can Top-Down Controls Expand the Ecological Niche of Marine N 2 Fixers? Front Microbiol 2021; 12:690200. [PMID: 34489886 PMCID: PMC8416505 DOI: 10.3389/fmicb.2021.690200] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Accepted: 07/05/2021] [Indexed: 01/12/2023] Open
Abstract
The ability of marine diazotrophs to fix dinitrogen gas (N2) is one of the most influential yet enigmatic processes in the ocean. With their activity diazotrophs support biological production by fixing about 100–200 Tg N/year and turning otherwise unavailable dinitrogen into bioavailable nitrogen (N), an essential limiting nutrient. Despite their important role, the factors that control the distribution of diazotrophs and their ability to fix N2 are not fully elucidated. We discuss insights that can be gained from the emerging picture of a wide geographical distribution of marine diazotrophs and provide a critical assessment of environmental (bottom-up) versus trophic (top-down) controls. We expand a simplified theoretical framework to understand how top-down control affects competition for resources that determine ecological niches. Selective mortality, mediated by grazing or viral-lysis, on non-fixing phytoplankton is identified as a critical process that can broaden the ability of diazotrophs to compete for resources in top-down controlled systems and explain an expanded ecological niche for diazotrophs. Our simplified analysis predicts a larger importance of top-down control on competition patterns as resource levels increase. As grazing controls the faster growing phytoplankton, coexistence of the slower growing diazotrophs can be established. However, these predictions require corroboration by experimental and field data, together with the identification of specific traits of organisms and associated trade-offs related to selective top-down control. Elucidation of these factors could greatly improve our predictive capability for patterns and rates of marine N2 fixation. The susceptibility of this key biogeochemical process to future changes may not only be determined by changes in environmental conditions but also via changes in the ecological interactions.
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Affiliation(s)
- Angela Landolfi
- Institute of Marine Sciences, National Research Council, Rome, Italy.,Marine Biogeochemistry, GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
| | - A E Friederike Prowe
- Marine Biogeochemistry, GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
| | - Markus Pahlow
- Marine Biogeochemistry, GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
| | - Christopher J Somes
- Marine Biogeochemistry, GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
| | - Chia-Te Chien
- Marine Biogeochemistry, GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
| | - Markus Schartau
- Marine Biogeochemistry, GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
| | - Wolfgang Koeve
- Marine Biogeochemistry, GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
| | - Andreas Oschlies
- Marine Biogeochemistry, GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
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22
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Global distribution patterns of marine nitrogen-fixers by imaging and molecular methods. Nat Commun 2021; 12:4160. [PMID: 34230473 PMCID: PMC8260585 DOI: 10.1038/s41467-021-24299-y] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Accepted: 06/08/2021] [Indexed: 12/02/2022] Open
Abstract
Nitrogen fixation has a critical role in marine primary production, yet our understanding of marine nitrogen-fixers (diazotrophs) is hindered by limited observations. Here, we report a quantitative image analysis pipeline combined with mapping of molecular markers for mining >2,000,000 images and >1300 metagenomes from surface, deep chlorophyll maximum and mesopelagic seawater samples across 6 size fractions (<0.2–2000 μm). We use this approach to characterise the diversity, abundance, biovolume and distribution of symbiotic, colony-forming and particle-associated diazotrophs at a global scale. We show that imaging and PCR-free molecular data are congruent. Sequence reads indicate diazotrophs are detected from the ultrasmall bacterioplankton (<0.2 μm) to mesoplankton (180–2000 μm) communities, while images predict numerous symbiotic and colony-forming diazotrophs (>20 µm). Using imaging and molecular data, we estimate that polyploidy can substantially affect gene abundances of symbiotic versus colony-forming diazotrophs. Our results support the canonical view that larger diazotrophs (>10 μm) dominate the tropical belts, while unicellular cyanobacterial and non-cyanobacterial diazotrophs are globally distributed in surface and mesopelagic layers. We describe co-occurring diazotrophic lineages of different lifestyles and identify high-density regions of diazotrophs in the global ocean. Overall, we provide an update of marine diazotroph biogeographical diversity and present a new bioimaging-bioinformatic workflow. Nitrogen fixation by diazotrophs is critical for marine primary production. Using Tara Oceans datasets, this study combines a quantitative image analysis pipeline with metagenomic mining to provide an improved global overview of diazotroph abundance, diversity and distribution.
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23
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Chakraborty S, Andersen KH, Visser AW, Inomura K, Follows MJ, Riemann L. Quantifying nitrogen fixation by heterotrophic bacteria in sinking marine particles. Nat Commun 2021; 12:4085. [PMID: 34215729 PMCID: PMC8253789 DOI: 10.1038/s41467-021-23875-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 05/21/2021] [Indexed: 02/06/2023] Open
Abstract
Nitrogen ([Formula: see text]) fixation by heterotrophic bacteria associated with sinking particles contributes to marine N cycling, but a mechanistic understanding of its regulation and significance are not available. Here we develop a mathematical model for unicellular heterotrophic bacteria growing on sinking marine particles. These bacteria can fix [Formula: see text] under suitable environmental conditions. We find that the interactive effects of polysaccharide and polypeptide concentrations, sinking speed of particles, and surrounding [Formula: see text] and [Formula: see text] concentrations determine the [Formula: see text] fixation rate inside particles. [Formula: see text] fixation inside sinking particles is mainly fueled by [Formula: see text] respiration rather than [Formula: see text] respiration. Our model suggests that anaerobic processes, including heterotrophic [Formula: see text] fixation, can take place in anoxic microenvironments inside sinking particles even in fully oxygenated marine waters. The modelled [Formula: see text] fixation rates are similar to bulk rates measured in the aphotic ocean, and our study consequently suggests that particle-associated heterotrophic [Formula: see text] fixation contributes significantly to oceanic [Formula: see text] fixation.
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Affiliation(s)
- Subhendu Chakraborty
- grid.5254.60000 0001 0674 042XDepartment of Biology, Marine Biological Section, University of Copenhagen, Helsingør, Denmark ,grid.5170.30000 0001 2181 8870Centre for Ocean Life, DTU Aqua, Technical University of Denmark, Kgs.Lyngby, Denmark ,grid.461729.f0000 0001 0215 3324Present Address: Systems Ecology Group, Leibniz Centre for Tropical Marine Research (ZMT), Bremen, Germany
| | - Ken H. Andersen
- grid.5170.30000 0001 2181 8870Centre for Ocean Life, DTU Aqua, Technical University of Denmark, Kgs.Lyngby, Denmark
| | - André W. Visser
- grid.5170.30000 0001 2181 8870Centre for Ocean Life, DTU Aqua, Technical University of Denmark, Kgs.Lyngby, Denmark
| | - Keisuke Inomura
- grid.20431.340000 0004 0416 2242Graduate School of Oceanography, University of Rhode Island, Narragansett, RI USA
| | - Michael J. Follows
- grid.116068.80000 0001 2341 2786Department of Earth, Atmospheric and Planetary Sciences, MIT, Cambridge, MA USA
| | - Lasse Riemann
- grid.5254.60000 0001 0674 042XDepartment of Biology, Marine Biological Section, University of Copenhagen, Helsingør, Denmark
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24
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Cheung S, Zehr JP, Xia X, Tsurumoto C, Endo H, Nakaoka SI, Mak W, Suzuki K, Liu H. Gamma4: a genetically versatile Gammaproteobacterial nifH phylotype that is widely distributed in the North Pacific Ocean. Environ Microbiol 2021; 23:4246-4259. [PMID: 34046993 DOI: 10.1111/1462-2920.15604] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Revised: 05/15/2021] [Accepted: 05/16/2021] [Indexed: 11/30/2022]
Abstract
Despite the increasing reports of non-cyanobacterial diazotrophs (NCDs) in pelagic waters, only one NCD (GammaA) has been relatively well described, whose genome and physiology are still unclear. Here we present a comprehensive analysis of the biogeography and ecophysiology of a widely distributed NCD, Gamma4. Gamma4 was the most abundant Gammaproteobacterial NCD along transects across the subtropical North Pacific. Using quantitative PCR, Gamma4 was detectable throughout the surface waters of North Pacific (7°N-55°N, 138°E-80°W), whereas GammaA was detected at <2/3 of the stations. Gamma4 was abundant during autumn-winter and positively correlated with chlorophyll a, while GammaA thrived during spring-summer and was positively correlated with temperature. Environmental clones affiliated with Gamma4 were widely detected in pelagic waters, oxygen minimum zones and even dinoflagellate microbiomes. By analysing the metabolic potential of a genome of Gamma4 reconstructed from the Tara Oceans dataset, we suggest that Gamma4 is a versatile heterotrophic NCD equipped with multiple strategies in scavenging phosphate (and iron) and for respiratory protection of nitrogenase. The transcription of nitrogenase genes is putatively regulated by Fnr-NifL-NifA and GlnD-GlnK systems that respond to intracellular oxygen and glutamate concentration. These results provide important implications for the potential life strategies of pelagic NCDs.
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Affiliation(s)
- Shunyan Cheung
- Department of Ocean Science, The Hong Kong University of Science and Technology, Hong Kong, China.,Hong Kong Branch of Southern Marine Science & Engineering Guangdong Laboratory, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Jonathan P Zehr
- Ocean Sciences Department, University of California Santa Cruz, Santa Cruz, CA, USA
| | - Xiaomin Xia
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
| | - Chihiro Tsurumoto
- Graduate School of Environmental Science, Hokkaido University, Sapporo, 060-0810, Japan
| | - Hisashi Endo
- Bioinformatics Center, Institute for Chemical Research, Kyoto University, Kyoto, 611-0011, Japan
| | - Shin-Ichiro Nakaoka
- Center for Global Environmental Research, National Institute for Environmental Studies, Tsukuba, Japan
| | - Wingkwan Mak
- Ocean Sciences Department, University of California Santa Cruz, Santa Cruz, CA, USA
| | - Koji Suzuki
- Graduate School of Environmental Science, Hokkaido University, Sapporo, 060-0810, Japan.,Faculty of Environmental Earth Science, Hokkaido University, Sapporo, 060-0810, Japan
| | - Hongbin Liu
- Department of Ocean Science, The Hong Kong University of Science and Technology, Hong Kong, China.,Hong Kong Branch of Southern Marine Science & Engineering Guangdong Laboratory, The Hong Kong University of Science and Technology, Hong Kong, China
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25
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Acinas SG, Sánchez P, Salazar G, Cornejo-Castillo FM, Sebastián M, Logares R, Royo-Llonch M, Paoli L, Sunagawa S, Hingamp P, Ogata H, Lima-Mendez G, Roux S, González JM, Arrieta JM, Alam IS, Kamau A, Bowler C, Raes J, Pesant S, Bork P, Agustí S, Gojobori T, Vaqué D, Sullivan MB, Pedrós-Alió C, Massana R, Duarte CM, Gasol JM. Deep ocean metagenomes provide insight into the metabolic architecture of bathypelagic microbial communities. Commun Biol 2021; 4:604. [PMID: 34021239 PMCID: PMC8139981 DOI: 10.1038/s42003-021-02112-2] [Citation(s) in RCA: 85] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 04/16/2021] [Indexed: 02/04/2023] Open
Abstract
The deep sea, the largest ocean's compartment, drives planetary-scale biogeochemical cycling. Yet, the functional exploration of its microbial communities lags far behind other environments. Here we analyze 58 metagenomes from tropical and subtropical deep oceans to generate the Malaspina Gene Database. Free-living or particle-attached lifestyles drive functional differences in bathypelagic prokaryotic communities, regardless of their biogeography. Ammonia and CO oxidation pathways are enriched in the free-living microbial communities and dissimilatory nitrate reduction to ammonium and H2 oxidation pathways in the particle-attached, while the Calvin Benson-Bassham cycle is the most prevalent inorganic carbon fixation pathway in both size fractions. Reconstruction of the Malaspina Deep Metagenome-Assembled Genomes reveals unique non-cyanobacterial diazotrophic bacteria and chemolithoautotrophic prokaryotes. The widespread potential to grow both autotrophically and heterotrophically suggests that mixotrophy is an ecologically relevant trait in the deep ocean. These results expand our understanding of the functional microbial structure and metabolic capabilities of the largest Earth aquatic ecosystem.
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Affiliation(s)
- Silvia G Acinas
- Department of Marine Biology and Oceanography, Institute of Marine Sciences (ICM), CSIC, Barcelona, Spain.
| | - Pablo Sánchez
- Department of Marine Biology and Oceanography, Institute of Marine Sciences (ICM), CSIC, Barcelona, Spain
| | - Guillem Salazar
- Department of Marine Biology and Oceanography, Institute of Marine Sciences (ICM), CSIC, Barcelona, Spain
- Department of Biology, Institute of Microbiology and Swiss Institute of Bioinformatics, ETH Zurich, Zurich, Switzerland
| | - Francisco M Cornejo-Castillo
- Department of Marine Biology and Oceanography, Institute of Marine Sciences (ICM), CSIC, Barcelona, Spain
- Department of Ocean Sciences, University of California, Santa Cruz, CA, USA
| | - Marta Sebastián
- Department of Marine Biology and Oceanography, Institute of Marine Sciences (ICM), CSIC, Barcelona, Spain
- Instituto de Oceanografía y Cambio Global, IOCAG, Universidad de Las Palmas de Gran Canaria, ULPGC, Gran Canaria, Spain
| | - Ramiro Logares
- Department of Marine Biology and Oceanography, Institute of Marine Sciences (ICM), CSIC, Barcelona, Spain
| | - Marta Royo-Llonch
- Department of Marine Biology and Oceanography, Institute of Marine Sciences (ICM), CSIC, Barcelona, Spain
| | - Lucas Paoli
- Department of Biology, Institute of Microbiology and Swiss Institute of Bioinformatics, ETH Zurich, Zurich, Switzerland
| | - Shinichi Sunagawa
- Department of Biology, Institute of Microbiology and Swiss Institute of Bioinformatics, ETH Zurich, Zurich, Switzerland
| | - Pascal Hingamp
- Aix Marseille Univ., Université de Toulon, CNRS, Marseille, France
| | - Hiroyuki Ogata
- Institute for Chemical Research, Kyoto University, Gokasho, Uji, Japan
| | - Gipsi Lima-Mendez
- Cellular and Molecular Microbiology, Faculté des Sciences, Université libre de Bruxelles (ULB), Brussels, Belgium
- Interuniversity Institute for Bioinformatics in Brussels, ULB-VUB, Brussels, Belgium
| | - Simon Roux
- Department of Microbiology, The Ohio State University, Columbus, OH, USA
- U.S. Department of Energy Joint Genome Institute, Berkeley, CA, USA
| | - José M González
- Department of Microbiology, University of La Laguna, La Laguna, Spain
| | - Jesús M Arrieta
- Spanish Institute of Oceanography (IEO), Oceanographic Center of The Canary Islands, Dársena Pesquera, Santa Cruz de Tenerife, Spain
| | - Intikhab S Alam
- King Abdullah University of Science and Technology (KAUST), Computational Bioscience Research Center (CBRC), Thuwal, Saudi Arabia
| | - Allan Kamau
- King Abdullah University of Science and Technology (KAUST), Computational Bioscience Research Center (CBRC), Thuwal, Saudi Arabia
| | - Chris Bowler
- Institut de Biologie de l'ENS (IBENS), Département de biologie, École normale supérieure, CNRS, INSERM, Université PSL, Paris, France
- Research Federation for the study of Global Ocean Systems Ecology and Evolution, Paris, France
| | - Jeroen Raes
- Department of Microbiology and Immunology, Rega Institute, KU Leuven - University of Leuven, Leuven, Belgium
- VIB Center for Microbiology, Leuven, Belgium
| | - Stéphane Pesant
- European Molecular Biology Laboratory, European Bioinformatics Institute (EMBL-EBI), Wellcome Genome Campus, Hinxton, Cambridge, United Kingdom
- PANGAEA, Data Publisher for Earth and Environmental Science, University of Bremen, Bremen, Germany
| | - Peer Bork
- Structural and Computational Biology, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Susana Agustí
- King Abdullah University of Science and Technology (KAUST), Red Sea Research Center (RSRC), Thuwal, Saudi Arabia
| | - Takashi Gojobori
- King Abdullah University of Science and Technology (KAUST), Computational Bioscience Research Center (CBRC), Thuwal, Saudi Arabia
| | - Dolors Vaqué
- Department of Marine Biology and Oceanography, Institute of Marine Sciences (ICM), CSIC, Barcelona, Spain
| | - Matthew B Sullivan
- Department of Microbiology and Civil Environmental and Geodetic Engineering, The Ohio State University, Columbus, OH, USA
| | - Carlos Pedrós-Alió
- Department of Systems Biology, Centro Nacional de Biotecnología (CNB), CSIC, Madrid, Spain
| | - Ramon Massana
- Department of Marine Biology and Oceanography, Institute of Marine Sciences (ICM), CSIC, Barcelona, Spain
| | - Carlos M Duarte
- King Abdullah University of Science and Technology (KAUST), Red Sea Research Center (RSRC) and Computational Bioscience Research Center (CBRC), Thuwal, Saudi Arabia
| | - Josep M Gasol
- Department of Marine Biology and Oceanography, Institute of Marine Sciences (ICM), CSIC, Barcelona, Spain
- Centre for Marine Ecosystems Research, School of Sciences, Edith Cowan University, Joondalup, WA, Australia
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26
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Ling J, Zhou W, Yang Q, Lin X, Zhang Y, Ahmad M, Peng Q, Dong J. Effect of PAHs on nitrogen-fixing and sulfate-reducing microbial communities in seagrass Enhalus acoroides sediment. Arch Microbiol 2021; 203:3443-3456. [PMID: 33893827 DOI: 10.1007/s00203-021-02321-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 04/02/2021] [Accepted: 04/05/2021] [Indexed: 10/21/2022]
Abstract
Seagrass meadows are vital ecosystems with high productivity and biodiversity and often in the oligotrophic area. Nitrogen usually limits productivity in this ecosystem as the main nutrient factor. Biological nitrogen fixation by diazotrophs in the rhizosphere sediment can introduce "new" nitrogen into the ecosystem. Previous studies revealed that most sulfate-reducing bacteria (SRB) can also fix nitrogen like the nitrogen-fixing bacteria (NFB). Moreover, both sulfate reduction and nitrogen fixation were affected by the organic pollutant. However, rare information is available regarding the NFB and SRB community composition and their temporal response to the pollutant. The quantitative real-time polymerase chain reaction and polymerase chain reaction denaturing gradient gel electrophoresis have been used to analyze NFB and SRB communities' shifts under different PAHs concentrations. They both experienced a dramatic shift under PAHs stress but exhibited different patterns. SRB could use the low and high concentration PAHs at the early stage of the incubation, while only the low concentration of PAHs could stimulate the growth of NFB through the whole incubation period. The predominant species of NFB communities were Alphaproteobacteria, Gammaproteobacteria, and Deltaproteobacteria; while for SRB communities were class Epsilonproteobacteria. Redundancy analysis indicated the significant environmental factors for the two communities were both ammonium and pH (P < 0.05). There existed nifH sequences related to known nitrogen fixing SRB Desulfatibacillum alkenivorans, which confirmed that microbial N2 fixation and sulfate reduction were coupled in the seagrass ecosystem by molecular technique. Our investigation provides new insight into the NFB and SRB community in the seagrass meadow.
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Affiliation(s)
- Juan Ling
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China.,Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, 5114583, China.,Key Laboratory of Tropical Marine Biotechnology of Hainan Province, Sanya Institute of Oceanology, SCSIO, Sanya, 572000, China.,Sanya National Marine Ecosystem Research Station, Tropical Marine Biological Research Station in Hainan, Chinese Academy of Sciences, Sanya, 572000, China.,Innovation Academy of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, Guangzhou, 5114583, China
| | - Weiguo Zhou
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China.,Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, 5114583, China.,Sanya National Marine Ecosystem Research Station, Tropical Marine Biological Research Station in Hainan, Chinese Academy of Sciences, Sanya, 572000, China.,Innovation Academy of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, Guangzhou, 5114583, China
| | - Qingsong Yang
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China.,Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, 5114583, China.,Sanya National Marine Ecosystem Research Station, Tropical Marine Biological Research Station in Hainan, Chinese Academy of Sciences, Sanya, 572000, China.,Innovation Academy of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, Guangzhou, 5114583, China
| | - Xiancheng Lin
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Ying Zhang
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Manzoor Ahmad
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Qinying Peng
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Junde Dong
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China. .,Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, 5114583, China. .,Key Laboratory of Tropical Marine Biotechnology of Hainan Province, Sanya Institute of Oceanology, SCSIO, Sanya, 572000, China. .,Sanya National Marine Ecosystem Research Station, Tropical Marine Biological Research Station in Hainan, Chinese Academy of Sciences, Sanya, 572000, China. .,Innovation Academy of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, Guangzhou, 5114583, China.
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27
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Current knowledge and recent advances in understanding metabolism of the model cyanobacterium Synechocystis sp. PCC 6803. Biosci Rep 2021; 40:222317. [PMID: 32149336 PMCID: PMC7133116 DOI: 10.1042/bsr20193325] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 03/05/2020] [Accepted: 03/06/2020] [Indexed: 02/06/2023] Open
Abstract
Cyanobacteria are key organisms in the global ecosystem, useful models for studying metabolic and physiological processes conserved in photosynthetic organisms, and potential renewable platforms for production of chemicals. Characterizing cyanobacterial metabolism and physiology is key to understanding their role in the environment and unlocking their potential for biotechnology applications. Many aspects of cyanobacterial biology differ from heterotrophic bacteria. For example, most cyanobacteria incorporate a series of internal thylakoid membranes where both oxygenic photosynthesis and respiration occur, while CO2 fixation takes place in specialized compartments termed carboxysomes. In this review, we provide a comprehensive summary of our knowledge on cyanobacterial physiology and the pathways in Synechocystis sp. PCC 6803 (Synechocystis) involved in biosynthesis of sugar-based metabolites, amino acids, nucleotides, lipids, cofactors, vitamins, isoprenoids, pigments and cell wall components, in addition to the proteins involved in metabolite transport. While some pathways are conserved between model cyanobacteria, such as Synechocystis, and model heterotrophic bacteria like Escherichia coli, many enzymes and/or pathways involved in the biosynthesis of key metabolites in cyanobacteria have not been completely characterized. These include pathways required for biosynthesis of chorismate and membrane lipids, nucleotides, several amino acids, vitamins and cofactors, and isoprenoids such as plastoquinone, carotenoids, and tocopherols. Moreover, our understanding of photorespiration, lipopolysaccharide assembly and transport, and degradation of lipids, sucrose, most vitamins and amino acids, and haem, is incomplete. We discuss tools that may aid our understanding of cyanobacterial metabolism, notably CyanoSource, a barcoded library of targeted Synechocystis mutants, which will significantly accelerate characterization of individual proteins.
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28
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Benavides M, Duhamel S, Van Wambeke F, Shoemaker KM, Moisander PH, Salamon E, Riemann L, Bonnet S. Dissolved organic matter stimulates N2 fixation and nifH gene expression in Trichodesmium. FEMS Microbiol Lett 2021; 367:5743415. [PMID: 32083662 DOI: 10.1093/femsle/fnaa034] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 02/20/2020] [Indexed: 12/15/2022] Open
Abstract
Mixotrophy, the combination of heterotrophic and autotrophic nutrition modes, is emerging as the rule rather than the exception in marine photosynthetic plankton. Trichodesmium, a prominent diazotroph ubiquitous in the (sub)tropical oceans, is generally considered to obtain energy via autotrophy. While the ability of Trichodesmium to use dissolved organic phosphorus when deprived of inorganic phosphorus sources is well known, the extent to which this important cyanobacterium may benefit from other dissolved organic matter (DOM) resources is unknown. Here we provide evidence of carbon-, nitrogen- and phosphorus-rich DOM molecules enhancing N2 fixation rates and nifH gene expression in natural Trichodesmium colonies collected at two stations in the western tropical South Pacific. Sampling at a third station located in the oligotrophic South Pacific Gyre revealed no Trichodesmium but showed presence of UCYN-B, although no nifH expression was detected. Our results suggest that Trichodesmium behaves mixotrophically in response to certain environmental conditions, providing them with metabolic plasticity and adding up to the view that mixotrophy is widespread among marine microbes.
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Affiliation(s)
- Mar Benavides
- Aix Marseille Univ., Université de Toulon, CNRS, IRD, MIO UM 110, 13288, Marseille, France
| | - Solange Duhamel
- Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964, USA
| | - France Van Wambeke
- Aix Marseille Univ., Université de Toulon, CNRS, IRD, MIO UM 110, 13288, Marseille, France
| | - Katyanne M Shoemaker
- Department of Biology, University of Massachusetts Dartmouth, 285 Old Westport Road, North Dartmouth, MA 02747, USA
| | - Pia H Moisander
- Department of Biology, University of Massachusetts Dartmouth, 285 Old Westport Road, North Dartmouth, MA 02747, USA
| | - Ellen Salamon
- Department of Biology, University of Copenhagen, Strandpromenaden 5, 3000 Helsingør, Denmark
| | - Lasse Riemann
- Department of Biology, University of Copenhagen, Strandpromenaden 5, 3000 Helsingør, Denmark
| | - Sophie Bonnet
- Aix Marseille Univ., Université de Toulon, CNRS, IRD, MIO UM 110, 13288, Marseille, France
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von Friesen LW, Riemann L. Nitrogen Fixation in a Changing Arctic Ocean: An Overlooked Source of Nitrogen? Front Microbiol 2021; 11:596426. [PMID: 33391213 PMCID: PMC7775723 DOI: 10.3389/fmicb.2020.596426] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Accepted: 11/17/2020] [Indexed: 11/13/2022] Open
Abstract
The Arctic Ocean is the smallest ocean on Earth, yet estimated to play a substantial role as a global carbon sink. As climate change is rapidly changing fundamental components of the Arctic, it is of local and global importance to understand and predict consequences for its carbon dynamics. Primary production in the Arctic Ocean is often nitrogen-limited, and this is predicted to increase in some regions. It is therefore of critical interest that biological nitrogen fixation, a process where some bacteria and archaea termed diazotrophs convert nitrogen gas to bioavailable ammonia, has now been detected in the Arctic Ocean. Several studies report diverse and active diazotrophs on various temporal and spatial scales across the Arctic Ocean. Their ecology and biogeochemical impact remain poorly known, and nitrogen fixation is so far absent from models of primary production in the Arctic Ocean. The composition of the diazotroph community appears distinct from other oceans – challenging paradigms of function and regulation of nitrogen fixation. There is evidence of both symbiotic cyanobacterial nitrogen fixation and heterotrophic diazotrophy, but large regions are not yet sampled, and the sparse quantitative data hamper conclusive insights. Hence, it remains to be determined to what extent nitrogen fixation represents a hitherto overlooked source of new nitrogen to consider when predicting future productivity of the Arctic Ocean. Here, we discuss current knowledge on diazotroph distribution, composition, and activity in pelagic and sea ice-associated environments of the Arctic Ocean. Based on this, we identify gaps and outline pertinent research questions in the context of a climate change-influenced Arctic Ocean – with the aim of guiding and encouraging future research on nitrogen fixation in this region.
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Affiliation(s)
- Lisa W von Friesen
- Marine Biology Section, Department of Biology, University of Copenhagen, Helsingør, Denmark
| | - Lasse Riemann
- Marine Biology Section, Department of Biology, University of Copenhagen, Helsingør, Denmark
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Intriguing size distribution of the uncultured and globally widespread marine non-cyanobacterial diazotroph Gamma-A. ISME JOURNAL 2020; 15:124-128. [PMID: 32918066 DOI: 10.1038/s41396-020-00765-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 08/18/2020] [Accepted: 08/27/2020] [Indexed: 01/09/2023]
Abstract
Non-cyanobacterial diazotrophs (NCDs) have recently emerged as potentially important contributors to marine nitrogen fixation. One of the most widely distributed NCDs is Gamma-A, yet information about its autecology is still scarce and solely relies on the PCR-based detection of its nitrogenase (nifH) gene in seawater, since previous metagenomic surveys targeting free-living planktonic size fractions (<3 μm) have not detected it. Here, we explore the diversity, biogeography, size-distribution, and nitrogenase gene expression of Gamma-A across four larger planktonic size-fractions (0.8-5, 5-20, 20-180, and 180-2000 μm) using metagenomes and metatranscriptomes from the Tara Oceans. We detected a single variant of a complete Gamma-A nifH gene along with other nitrogenase-related genes (nifKDT) within a metatranscriptomic-based contig of the Marine Atlas of Tara Ocean Unigenes. Gamma-A was detected in tropical and subtropical oceanic regions across all the size-fractions. However, the highest gene and transcript abundances were found in the 0.8-5 and 5-20 μm size-fractions at the surface, whereas abundances at the deep chlorophyll maximum were lower and similar across all size-fractions. The ubiquitous presence of active Gamma-A in large planktonic size-fractions suggests a filamentous or particle-attached lifestyle and places its potential to fix nitrogen in larger planktonic compartments.
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31
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Zhang X, Ward BB, Sigman DM. Global Nitrogen Cycle: Critical Enzymes, Organisms, and Processes for Nitrogen Budgets and Dynamics. Chem Rev 2020; 120:5308-5351. [DOI: 10.1021/acs.chemrev.9b00613] [Citation(s) in RCA: 70] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Xinning Zhang
- Department of Geosciences, Princeton University, Princeton, New Jersey 08544, United States
- Princeton Environmental Institute, Princeton University, Princeton, New Jersey 08544, United States
| | - Bess B. Ward
- Department of Geosciences, Princeton University, Princeton, New Jersey 08544, United States
- Princeton Environmental Institute, Princeton University, Princeton, New Jersey 08544, United States
| | - Daniel M. Sigman
- Department of Geosciences, Princeton University, Princeton, New Jersey 08544, United States
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32
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Jabir T, Vipindas PV, Jesmi Y, Valliyodan S, Parambath PM, Singh A, Abdulla MH. Nutrient stoichiometry (N:P) controls nitrogen fixation and distribution of diazotrophs in a tropical eutrophic estuary. MARINE POLLUTION BULLETIN 2020; 151:110799. [PMID: 32056594 DOI: 10.1016/j.marpolbul.2019.110799] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 11/26/2019] [Accepted: 12/03/2019] [Indexed: 06/10/2023]
Abstract
Nitrogen fixation and its ecological regulation are poorly understood in the tropical estuaries, which are highly influenced by anthropogenic disturbances. In this study, we investigated the role of nutrient stoichiometry in the diversity, abundance and activity of N2-fixing bacterial community and their seasonal variations in the water column of a tropical eutrophic estuary (Cochin estuary). The N2 fixation rates in the estuary ranged from 0.1 to 2.0 nmol N2 l-1 h-1, with higher activity during post-monsoon and lower during monsoon. The rates are appeared to be primarily controlled by dissolved inorganic nitrogen and phosphorous (N:P) ratio. Clone library analysis of nitrogenase (nifH) gene revealed that the major N2 fixing phylotypes belong to Cluster I and Cluster III diazotrophs. The overall findings of this study suggest that monsoon induced seasonal changes in nutrient stoichiometry control the distribution and activity of diazotrophs in a tropical estuary.
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Affiliation(s)
- Thajudeen Jabir
- Department of Marine Biology, Microbiology and Biochemistry, School of Marine Sciences, Cochin University of Science and Technology, Fine Arts Avenue, Kochi 682016, Kerala, India.
| | - Puthiya Veettil Vipindas
- Department of Marine Biology, Microbiology and Biochemistry, School of Marine Sciences, Cochin University of Science and Technology, Fine Arts Avenue, Kochi 682016, Kerala, India
| | - Yousuf Jesmi
- Department of Marine Biology, Microbiology and Biochemistry, School of Marine Sciences, Cochin University of Science and Technology, Fine Arts Avenue, Kochi 682016, Kerala, India; School of Environmental Sciences, Mahatma Gandhi University, Kottayam, Kerala 686560, India
| | - Sudheesh Valliyodan
- Department of Marine Biology, Microbiology and Biochemistry, School of Marine Sciences, Cochin University of Science and Technology, Fine Arts Avenue, Kochi 682016, Kerala, India; Centre for Marine Living Resources and Ecology, LNG Rd, Puthuvype, Kochi, Kerala, India 682508
| | | | - Arvind Singh
- Physical Research Laboratory, Ahmedabad 380 009, India
| | - Mohamed Hatha Abdulla
- Department of Marine Biology, Microbiology and Biochemistry, School of Marine Sciences, Cochin University of Science and Technology, Fine Arts Avenue, Kochi 682016, Kerala, India.
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Salazar G, Paoli L, Alberti A, Huerta-Cepas J, Ruscheweyh HJ, Cuenca M, Field CM, Coelho LP, Cruaud C, Engelen S, Gregory AC, Labadie K, Marec C, Pelletier E, Royo-Llonch M, Roux S, Sánchez P, Uehara H, Zayed AA, Zeller G, Carmichael M, Dimier C, Ferland J, Kandels S, Picheral M, Pisarev S, Poulain J, Acinas SG, Babin M, Bork P, Bowler C, de Vargas C, Guidi L, Hingamp P, Iudicone D, Karp-Boss L, Karsenti E, Ogata H, Pesant S, Speich S, Sullivan MB, Wincker P, Sunagawa S. Gene Expression Changes and Community Turnover Differentially Shape the Global Ocean Metatranscriptome. Cell 2019; 179:1068-1083.e21. [PMID: 31730850 PMCID: PMC6912165 DOI: 10.1016/j.cell.2019.10.014] [Citation(s) in RCA: 181] [Impact Index Per Article: 36.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2019] [Revised: 07/26/2019] [Accepted: 10/11/2019] [Indexed: 12/02/2022]
Abstract
Ocean microbial communities strongly influence the biogeochemistry, food webs, and climate of our planet. Despite recent advances in understanding their taxonomic and genomic compositions, little is known about how their transcriptomes vary globally. Here, we present a dataset of 187 metatranscriptomes and 370 metagenomes from 126 globally distributed sampling stations and establish a resource of 47 million genes to study community-level transcriptomes across depth layers from pole-to-pole. We examine gene expression changes and community turnover as the underlying mechanisms shaping community transcriptomes along these axes of environmental variation and show how their individual contributions differ for multiple biogeochemically relevant processes. Furthermore, we find the relative contribution of gene expression changes to be significantly lower in polar than in non-polar waters and hypothesize that in polar regions, alterations in community activity in response to ocean warming will be driven more strongly by changes in organismal composition than by gene regulatory mechanisms. VIDEO ABSTRACT.
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Affiliation(s)
- Guillem Salazar
- Department of Biology, Institute of Microbiology and Swiss Institute of Bioinformatics, ETH Zürich, Zürich 8093, Switzerland
| | - Lucas Paoli
- Department of Biology, Institute of Microbiology and Swiss Institute of Bioinformatics, ETH Zürich, Zürich 8093, Switzerland
| | - Adriana Alberti
- Génomique Métabolique, Genoscope, Institut de biologie François Jacob, Commissariat à l'Energie Atomique (CEA), CNRS, Université Evry, Université Paris-Saclay, Evry, France; Research Federation for the Study of Global Ocean Systems Ecology and Evolution, FR2022/GOSEE, 3 Rue Michel-Ange, Paris 75016, France
| | - Jaime Huerta-Cepas
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM) and Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Madrid 28223, Spain; Structural and Computational Biology, European Molecular Biology Laboratory, Heidelberg 69117, Germany
| | - Hans-Joachim Ruscheweyh
- Department of Biology, Institute of Microbiology and Swiss Institute of Bioinformatics, ETH Zürich, Zürich 8093, Switzerland
| | - Miguelangel Cuenca
- Department of Biology, Institute of Microbiology and Swiss Institute of Bioinformatics, ETH Zürich, Zürich 8093, Switzerland
| | - Christopher M Field
- Department of Biology, Institute of Microbiology and Swiss Institute of Bioinformatics, ETH Zürich, Zürich 8093, Switzerland
| | - Luis Pedro Coelho
- Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai 200433, China; Key Laboratory of Computational Neuroscience and Brain-Inspired Intelligence (Fudan University), Ministry of Education, Shanghai, China; Structural and Computational Biology, European Molecular Biology Laboratory, Heidelberg 69117, Germany
| | - Corinne Cruaud
- Research Federation for the Study of Global Ocean Systems Ecology and Evolution, FR2022/GOSEE, 3 Rue Michel-Ange, Paris 75016, France; Genoscope, Institut de biologie François-Jacob, Commissariat à l'Energie Atomique (CEA), Université Paris-Saclay, Evry, France
| | - Stefan Engelen
- Research Federation for the Study of Global Ocean Systems Ecology and Evolution, FR2022/GOSEE, 3 Rue Michel-Ange, Paris 75016, France; Genoscope, Institut de biologie François-Jacob, Commissariat à l'Energie Atomique (CEA), Université Paris-Saclay, Evry, France
| | - Ann C Gregory
- Department of Microbiology, the Ohio State University, Columbus, OH 43210, USA
| | - Karine Labadie
- Research Federation for the Study of Global Ocean Systems Ecology and Evolution, FR2022/GOSEE, 3 Rue Michel-Ange, Paris 75016, France; Genoscope, Institut de biologie François-Jacob, Commissariat à l'Energie Atomique (CEA), Université Paris-Saclay, Evry, France
| | - Claudie Marec
- Département de biologie, Université Laval, QC G1V 0A6, Canada; Laboratoire d'Oceanographie Physique et Spatiale, UMR 6523, CNRS-IFREMER-IRD-UBO, Plouzané, France
| | - Eric Pelletier
- Génomique Métabolique, Genoscope, Institut de biologie François Jacob, Commissariat à l'Energie Atomique (CEA), CNRS, Université Evry, Université Paris-Saclay, Evry, France; Research Federation for the Study of Global Ocean Systems Ecology and Evolution, FR2022/GOSEE, 3 Rue Michel-Ange, Paris 75016, France
| | - Marta Royo-Llonch
- Department of Marine Biology and Oceanography, Institute of Marine Sciences (ICM)-CSIC, Barcelona 08003, Spain
| | - Simon Roux
- Department of Microbiology, the Ohio State University, Columbus, OH 43210, USA
| | - Pablo Sánchez
- Department of Marine Biology and Oceanography, Institute of Marine Sciences (ICM)-CSIC, Barcelona 08003, Spain
| | - Hideya Uehara
- Institute for Chemical Research, Kyoto Univerisity, Gokasho, Uji 611-0011, Japan; Hewlett-Packard Japan, 2-2-1, Ojima, Koto-ku, Tokyo 136-8711, Japan
| | - Ahmed A Zayed
- Department of Microbiology, the Ohio State University, Columbus, OH 43210, USA
| | - Georg Zeller
- Structural and Computational Biology, European Molecular Biology Laboratory, Heidelberg 69117, Germany
| | - Margaux Carmichael
- Research Federation for the Study of Global Ocean Systems Ecology and Evolution, FR2022/GOSEE, 3 Rue Michel-Ange, Paris 75016, France; Sorbonne Université & CNRS, UMR 7144 (AD2M), ECOMAP, Station Biologique de Roscoff, Place Georges Teissier, Roscoff 29680, France
| | - Céline Dimier
- Research Federation for the Study of Global Ocean Systems Ecology and Evolution, FR2022/GOSEE, 3 Rue Michel-Ange, Paris 75016, France; Sorbonne Université, CNRS, Laboratoire d'Océanographie de Villefanche, LOV, Villefranche-sur-mer 06230, France; Institut de Biologie de l'ENS (IBENS), Département de biologie, École normale supérieure, CNRS, INSERM, Université PSL, Paris 75005, France
| | - Joannie Ferland
- Research Federation for the Study of Global Ocean Systems Ecology and Evolution, FR2022/GOSEE, 3 Rue Michel-Ange, Paris 75016, France; Takuvik Joint International Laboratory, CNRS-Université Laval, QC G1V 0A6, Canada
| | - Stefanie Kandels
- Structural and Computational Biology, European Molecular Biology Laboratory, Heidelberg 69117, Germany
| | - Marc Picheral
- Research Federation for the Study of Global Ocean Systems Ecology and Evolution, FR2022/GOSEE, 3 Rue Michel-Ange, Paris 75016, France; Sorbonne Université, CNRS, Laboratoire d'Océanographie de Villefanche, LOV, Villefranche-sur-mer 06230, France
| | - Sergey Pisarev
- Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow 117997, Russia
| | - Julie Poulain
- Génomique Métabolique, Genoscope, Institut de biologie François Jacob, Commissariat à l'Energie Atomique (CEA), CNRS, Université Evry, Université Paris-Saclay, Evry, France; Research Federation for the Study of Global Ocean Systems Ecology and Evolution, FR2022/GOSEE, 3 Rue Michel-Ange, Paris 75016, France
| | - Silvia G Acinas
- Department of Marine Biology and Oceanography, Institute of Marine Sciences (ICM)-CSIC, Barcelona 08003, Spain
| | - Marcel Babin
- Takuvik Joint International Laboratory, CNRS-Université Laval, QC G1V 0A6, Canada
| | - Peer Bork
- Structural and Computational Biology, European Molecular Biology Laboratory, Heidelberg 69117, Germany; Max Delbrück Centre for Molecular Medicine, Berlin 13125, Germany; Department of Bioinformatics, Biocenter, University of Würzburg, Würzburg 97074, Germany
| | - Chris Bowler
- Research Federation for the Study of Global Ocean Systems Ecology and Evolution, FR2022/GOSEE, 3 Rue Michel-Ange, Paris 75016, France; Institut de Biologie de l'ENS (IBENS), Département de biologie, École normale supérieure, CNRS, INSERM, Université PSL, Paris 75005, France
| | - Colomban de Vargas
- Research Federation for the Study of Global Ocean Systems Ecology and Evolution, FR2022/GOSEE, 3 Rue Michel-Ange, Paris 75016, France; Sorbonne Université & CNRS, UMR 7144 (AD2M), ECOMAP, Station Biologique de Roscoff, Place Georges Teissier, Roscoff 29680, France
| | - Lionel Guidi
- Research Federation for the Study of Global Ocean Systems Ecology and Evolution, FR2022/GOSEE, 3 Rue Michel-Ange, Paris 75016, France; Sorbonne Université & CNRS, UMR 7144 (AD2M), ECOMAP, Station Biologique de Roscoff, Place Georges Teissier, Roscoff 29680, France; Department of Oceanography, University of Hawaii, Honolulu, HI 96822, USA
| | - Pascal Hingamp
- Research Federation for the Study of Global Ocean Systems Ecology and Evolution, FR2022/GOSEE, 3 Rue Michel-Ange, Paris 75016, France; Aix Marseille Univ, Université de Toulon, CNRS, IRD, MIO, Marseille, France
| | | | - Lee Karp-Boss
- School of Marine Sciences, University of Maine, Orono, ME 04469, USA
| | - Eric Karsenti
- Institut de Biologie de l'ENS (IBENS), Département de biologie, École normale supérieure, CNRS, INSERM, Université PSL, Paris 75005, France; Directors' Research European Molecular Biology Laboratory, Heidelberg 69117, Germany
| | - Hiroyuki Ogata
- Institute for Chemical Research, Kyoto Univerisity, Gokasho, Uji 611-0011, Japan
| | - Stephane Pesant
- MARUM, Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany; PANGAEA, Data Publisher for Earth and Environmental Science, University of Bremen, Bremen, Germany
| | | | - Matthew B Sullivan
- Department of Microbiology, the Ohio State University, Columbus, OH 43210, USA; Department of Civil, Environmental and Geodetic Engineering, the Ohio State University, Columbus, OH 43214, USA; Center for RNA Biology, the Ohio State University, Columbus, OH 43214, USA
| | - Patrick Wincker
- Génomique Métabolique, Genoscope, Institut de biologie François Jacob, Commissariat à l'Energie Atomique (CEA), CNRS, Université Evry, Université Paris-Saclay, Evry, France; Research Federation for the Study of Global Ocean Systems Ecology and Evolution, FR2022/GOSEE, 3 Rue Michel-Ange, Paris 75016, France
| | - Shinichi Sunagawa
- Department of Biology, Institute of Microbiology and Swiss Institute of Bioinformatics, ETH Zürich, Zürich 8093, Switzerland.
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34
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Direct Detection of Heterotrophic Diazotrophs Associated with Planktonic Aggregates. Sci Rep 2019; 9:9288. [PMID: 31243322 PMCID: PMC6594930 DOI: 10.1038/s41598-019-45505-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 05/24/2019] [Indexed: 12/03/2022] Open
Abstract
N2 fixation by planktonic heterotrophic diazotrophs is more wide spread than previously thought, including environments considered “unfavorable” for diazotrophy. These environments include a substantial fraction of the aquatic biosphere such as eutrophic estuaries with high ambient nitrogen concentrations and oxidized aphotic water. Different studies suggested that heterotrophic diazotrophs associated with aggregates may promote N2 fixation in such environments. However, this association was never validated directly and relies mainly on indirect relationships and different statistical approaches. Here, we identified, for the first time, a direct link between active heterotrophic diazotrophs and aggregates that comprise polysaccharides. Our new staining method combines fluorescent tagging of active diazotrophs by nitrogenase-immunolabeling, polysaccharides staining by Alcian blue or concanavalin-A, and total bacteria via nucleic-acid staining. Concomitant to N2 fixation rates and bacterial activity, this new method provided specific localization of heterotrophic diazotrophs on artificial and natural aggregates. We postulate that the insights gained by this new visualization approach will have a broad significance for future research on the aquatic nitrogen cycle, including environments in which diazotrophy has traditionally been overlooked.
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35
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Pedersen JN, Bombar D, Paerl RW, Riemann L. Diazotrophs and N 2-Fixation Associated With Particles in Coastal Estuarine Waters. Front Microbiol 2018; 9:2759. [PMID: 30505296 PMCID: PMC6250843 DOI: 10.3389/fmicb.2018.02759] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 10/29/2018] [Indexed: 11/13/2022] Open
Abstract
Putative heterotrophic bacteria carrying out N2-fixation, so-called non-cyanobacterial diazotrophs (NCDs), are widely distributed in marine waters, but details of how the O2-inhibited N2-fixation process is promoted in the oxic water column remains ambiguous. Here we carried out two experiments with water from a eutrophic temperate fjord to examine whether low-oxygen microenvironments within particulate organic matter could be loci suitable for N2-fixation. First, water enriched with natural particles or sediment showed higher N2-fixation rates than bulk water, and nitrogenase genes (nifH) revealed that specific diazotrophs were affiliated with the particulate matter. Second, pristine artificial surfaces were rapidly colonized by diverse bacteria, while putative diazotrophs emerged relatively late (after 80 h) during the colonization, and phylotypes related to Pseudomonas and to anaerobic bacteria became dominant with time. Our study pinpoints natural particles as sites of N2-fixation, and indicates that resuspension of sediment material can elevate pelagic N2-fixation. Moreover, we show that diverse natural diazotrophs can colonize artificial surfaces, but colonization by “pioneer” bacterioplankton that more rapidly associate with surfaces appears to be a prerequisite. Whereas our experimental study supports the idea of pelagic particles as sites of N2-fixation by heterotrophic bacteria, future in situ studies are needed in order to establish identity, activity and ecology of particle associated NCDs as a function of individual particle characteristics.
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Affiliation(s)
- Jeppe N Pedersen
- Marine Biological Section, Department of Biology, University of Copenhagen, Helsingør, Denmark
| | - Deniz Bombar
- Marine Biological Section, Department of Biology, University of Copenhagen, Helsingør, Denmark
| | - Ryan W Paerl
- Marine Biological Section, Department of Biology, University of Copenhagen, Helsingør, Denmark
| | - Lasse Riemann
- Marine Biological Section, Department of Biology, University of Copenhagen, Helsingør, Denmark
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36
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Landolfi A, Kähler P, Koeve W, Oschlies A. Global Marine N 2 Fixation Estimates: From Observations to Models. Front Microbiol 2018; 9:2112. [PMID: 30283409 PMCID: PMC6157310 DOI: 10.3389/fmicb.2018.02112] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Accepted: 08/20/2018] [Indexed: 11/30/2022] Open
Abstract
Fixed nitrogen (N) limits productivity across much of the low-latitude ocean. The magnitude of its inventory results from the balance of N input and N loss, the latter largely occurring in regionally well-defined low-oxygen waters and sediments (denitrification and anammox). The rate and distribution of N input by biotic N2 fixation, the dominant N source, is not well known. Here we compile N2 fixation estimates from experimental measurements, tracer-based geochemical and modeling approaches, and discuss their limitations and uncertainties. The lack of adequate experimental data coverage and the insufficient understanding of the controls of marine N2 fixation result in high uncertainties, which make the assessment of the current N-balance a challenge. We suggest that a more comprehensive understanding of the environmental and ecological interaction of marine N2 fixers is required to advance the field toward robust N2 fixation rates estimates and predictions.
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Affiliation(s)
- Angela Landolfi
- GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
| | - Paul Kähler
- GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
| | - Wolfgang Koeve
- GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
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37
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Turk-Kubo KA, Connell P, Caron D, Hogan ME, Farnelid HM, Zehr JP. In Situ Diazotroph Population Dynamics Under Different Resource Ratios in the North Pacific Subtropical Gyre. Front Microbiol 2018; 9:1616. [PMID: 30090092 PMCID: PMC6068237 DOI: 10.3389/fmicb.2018.01616] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Accepted: 06/28/2018] [Indexed: 11/13/2022] Open
Abstract
Major advances in understanding the diversity, distribution, and activity of marine N2-fixing microorganisms (diazotrophs) have been made in the past decades, however, large gaps in knowledge remain about the environmental controls on growth and mortality rates. In order to measure diazotroph net growth rates and microzooplankton grazing rates on diazotrophs, nutrient perturbation experiments and dilution grazing experiments were conducted using free-floating in situ incubation arrays in the vicinity of Station ALOHA in March 2016. Net growth rates for targeted diazotroph taxa as well as Prochlorococcus, Synechococcus and photosynthetic picoeukaryotes were determined under high (H) and low (L) nitrate:phosphate (NP) ratio conditions at four depths in the photic zone (25, 45, 75, and 100 m) using quantitative PCR and flow cytometry. Changes in the prokaryote community composition in response to HNP and LNP treatments were characterized using 16S rRNA variable region tag sequencing. Microzooplankton grazing rates on diazotrophs were measured using a modified dilution technique at two depths in the photic zone (15 and 125 m). Net growth rates for most of the targeted diazotrophs after 48 h were not stimulated as expected by LNP conditions, rather enhanced growth rates were often measured in HNP treatments. Interestingly, net growth rates of the uncultivated prymnesiophyte symbiont UCYN-A1 were stimulated in HNP treatments at 75 and 100 m, suggesting that N used for growth was acquired through continuing to fix N2 in the presence of nitrate. Net growth rates for UCYN-A1, UCYN-C, Crocosphaera sp. (UCYN-B) and the diatom symbiont Richelia (associated with Rhizosolenia) were uniformly high at 45 m (up to 1.6 ± 0.5 d-1), implying that all were growing optimally at the onset of the experiment at that depth. Differences in microzooplankton grazing rates on UCYN-A1 and UCYN-C in 15 m waters indicate that the grazer assemblage preyed preferentially on UCYN-A1. Deeper in the water column (125 m), both diazotrophs were grazed at substantial rates, suggesting grazing pressure may increase with depth in the photic zone. Constraining in situ diazotroph growth and mortality rates are important steps for improving parameterization for diazotrophs in global ecosystem models.
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Affiliation(s)
- Kendra A. Turk-Kubo
- Department of Ocean Sciences, University of California, Santa Cruz, Santa Cruz, CA, United States
| | - Paige Connell
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, United States
| | - David Caron
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, United States
| | - Mary E. Hogan
- Department of Ocean Sciences, University of California, Santa Cruz, Santa Cruz, CA, United States
| | - Hanna M. Farnelid
- Department of Ocean Sciences, University of California, Santa Cruz, Santa Cruz, CA, United States
- Centre for Ecology and Evolution in Microbial Model Systems, Linnaeus University, Kalmar, Sweden
| | - Jonathan P. Zehr
- Department of Ocean Sciences, University of California, Santa Cruz, Santa Cruz, CA, United States
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