1
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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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2
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Koedooder C, Zhang F, Wang S, Basu S, Haley ST, Tolic N, Nicora CD, Glavina del Rio T, Dyhrman ST, Gledhill M, Boiteau RM, Rubin-Blum M, Shaked Y. Taxonomic distribution of metabolic functions in bacteria associated with Trichodesmium consortia. mSystems 2023; 8:e0074223. [PMID: 37916816 PMCID: PMC10734445 DOI: 10.1128/msystems.00742-23] [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: 07/26/2023] [Accepted: 09/21/2023] [Indexed: 11/03/2023] Open
Abstract
IMPORTANCE Colonies of the cyanobacteria Trichodesmium act as a biological hotspot for the usage and recycling of key resources such as C, N, P, and Fe within an otherwise oligotrophic environment. While Trichodesmium colonies are known to interact and support a unique community of algae and particle-associated microbes, our understanding of the taxa that populate these colonies and the gene functions they encode is still limited. Characterizing the taxa and adaptive strategies that influence consortium physiology and its concomitant biogeochemistry is critical in a future ocean predicted to have increasingly resource-depleted regions.
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Affiliation(s)
- Coco Koedooder
- The Fredy and Nadine Herrmann Institute of Earth Sciences, Hebrew University of Jerusalem, Jerusalem, Israel
- The Interuniversity Institute for Marine Sciences in Eilat, Eilat, Israel
- Israel Oceanographic and Limnological Research, Haifa, Israel
| | - Futing Zhang
- The Fredy and Nadine Herrmann Institute of Earth Sciences, Hebrew University of Jerusalem, Jerusalem, Israel
- The Interuniversity Institute for Marine Sciences in Eilat, Eilat, Israel
| | - Siyuan Wang
- The Fredy and Nadine Herrmann Institute of Earth Sciences, Hebrew University of Jerusalem, Jerusalem, Israel
- The Interuniversity Institute for Marine Sciences in Eilat, Eilat, Israel
| | - Subhajit Basu
- The Fredy and Nadine Herrmann Institute of Earth Sciences, Hebrew University of Jerusalem, Jerusalem, Israel
- The Interuniversity Institute for Marine Sciences in Eilat, Eilat, Israel
- Microsensor Research Group, Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Sheean T. Haley
- Lamont-Doherty Earth Observatory, Columbia University, New York, USA
| | - Nikola Tolic
- Earth and Biological Sciences, Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Carrie D. Nicora
- Earth and Biological Sciences, Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Tijana Glavina del Rio
- Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Sonya T. Dyhrman
- Lamont-Doherty Earth Observatory, Columbia University, New York, USA
- Department of Earth and Environmental Sciences, Columbia University, New York, USA
| | | | - Rene M. Boiteau
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington, USA
- College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, Oregon, USA
| | | | - Yeala Shaked
- The Fredy and Nadine Herrmann Institute of Earth Sciences, Hebrew University of Jerusalem, Jerusalem, Israel
- The Interuniversity Institute for Marine Sciences in Eilat, Eilat, Israel
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3
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Alexander H, Hu SK, Krinos AI, Pachiadaki M, Tully BJ, Neely CJ, Reiter T. Eukaryotic genomes from a global metagenomic data set illuminate trophic modes and biogeography of ocean plankton. mBio 2023; 14:e0167623. [PMID: 37947402 PMCID: PMC10746220 DOI: 10.1128/mbio.01676-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 09/27/2023] [Indexed: 11/12/2023] Open
Abstract
Metagenomics is a powerful method for interpreting the ecological roles and physiological capabilities of mixed microbial communities. Yet, many tools for processing metagenomic data are neither designed to consider eukaryotes nor are they built for an increasing amount of sequence data. EukHeist is an automated pipeline to retrieve eukaryotic and prokaryotic metagenome-assembled genomes (MAGs) from large-scale metagenomic sequence data sets. We developed the EukHeist workflow to specifically process large amounts of both metagenomic and/or metatranscriptomic sequence data in an automated and reproducible fashion. Here, we applied EukHeist to the large-size fraction data (0.8-2,000 µm) from Tara Oceans to recover both eukaryotic and prokaryotic MAGs, which we refer to as TOPAZ (Tara Oceans Particle-Associated MAGs). The TOPAZ MAGs consisted of >900 environmentally relevant eukaryotic MAGs and >4,000 bacterial and archaeal MAGs. The bacterial and archaeal TOPAZ MAGs expand upon the phylogenetic diversity of likely particle- and host-associated taxa. We use these MAGs to demonstrate an approach to infer the putative trophic mode of the recovered eukaryotic MAGs. We also identify ecological cohorts of co-occurring MAGs, which are driven by specific environmental factors and putative host-microbe associations. These data together add to a number of growing resources of environmentally relevant eukaryotic genomic information. Complementary and expanded databases of MAGs, such as those provided through scalable pipelines like EukHeist, stand to advance our understanding of eukaryotic diversity through increased coverage of genomic representatives across the tree of life.IMPORTANCESingle-celled eukaryotes play ecologically significant roles in the marine environment, yet fundamental questions about their biodiversity, ecological function, and interactions remain. Environmental sequencing enables researchers to document naturally occurring protistan communities, without culturing bias, yet metagenomic and metatranscriptomic sequencing approaches cannot separate individual species from communities. To more completely capture the genomic content of mixed protistan populations, we can create bins of sequences that represent the same organism (metagenome-assembled genomes [MAGs]). We developed the EukHeist pipeline, which automates the binning of population-level eukaryotic and prokaryotic genomes from metagenomic reads. We show exciting insight into what protistan communities are present and their trophic roles in the ocean. Scalable computational tools, like EukHeist, may accelerate the identification of meaningful genetic signatures from large data sets and complement researchers' efforts to leverage MAG databases for addressing ecological questions, resolving evolutionary relationships, and discovering potentially novel biodiversity.
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Affiliation(s)
- Harriet Alexander
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA
| | - Sarah K. Hu
- Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA
| | - Arianna I. Krinos
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA
- MIT-WHOI Joint Program in Oceanography/Applied Ocean Science and Engineering, Cambridge and Woods Hole, Massachusetts, USA
| | - Maria Pachiadaki
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA
| | - Benjamin J. Tully
- Department of Biological Sciences, University of Southern California, Los Angeles, California, USA
| | - Christopher J. Neely
- Department of Quantitative and Computational Biology, University of Southern California, Los Angeles, California, USA
| | - Taylor Reiter
- Population Health and Reproduction, University of California, Davis, Davis, California, USA
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4
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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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5
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Eichner M, Inomura K, Pierella Karlusich JJ, Shaked Y. Better together? Lessons on sociality from Trichodesmium. Trends Microbiol 2023; 31:1072-1084. [PMID: 37244772 DOI: 10.1016/j.tim.2023.05.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Revised: 04/30/2023] [Accepted: 05/01/2023] [Indexed: 05/29/2023]
Abstract
The N2-fixing cyanobacterium Trichodesmium is an important player in the oceanic nitrogen and carbon cycles. Trichodesmium occurs both as single trichomes and as colonies containing hundreds of trichomes. In this review, we explore the benefits and disadvantages of colony formation, considering physical, chemical, and biological effects from nanometer to kilometer scale. Showing that all major life challenges are affected by colony formation, we claim that Trichodesmium's ecological success is tightly linked to its colonial lifestyle. Microbial interactions in the microbiome, chemical gradients within the colony, interactions with particles, and elevated mobility in the water column shape a highly dynamic microenvironment. We postulate that these dynamics are key to the resilience of Trichodesmium and other colony formers in our changing environment.
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Affiliation(s)
- Meri Eichner
- Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, Třeboň, Czech Republic.
| | - Keisuke Inomura
- Graduate School of Oceanography, University of Rhode Island, Narragansett, RI, USA
| | | | - Yeala Shaked
- Freddy and Nadine Herrmann Institute of Earth Sciences, Hebrew University, Jerusalem, Israel; Interuniversity Institute for Marine Sciences, Eilat, Israel
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6
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Koedooder C, Landou E, Zhang F, Wang S, Basu S, Berman-Frank I, Shaked Y, Rubin-Blum M. Metagenomes of Red Sea Subpopulations Challenge the Use of Marker Genes and Morphology to Assess Trichodesmium Diversity. Front Microbiol 2022; 13:879970. [PMID: 35707175 PMCID: PMC9189399 DOI: 10.3389/fmicb.2022.879970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2022] [Accepted: 04/22/2022] [Indexed: 11/13/2022] Open
Abstract
Trichodesmium are filamentous cyanobacteria of key interest due to their ability to fix carbon and nitrogen within an oligotrophic marine environment. Their blooms consist of a dynamic assemblage of subpopulations and colony morphologies that are hypothesized to occupy unique niches. Here, we assessed the poorly studied diversity of Trichodesmium in the Red Sea, based on metagenome-assembled genomes (MAGs) and hetR gene-based phylotyping. We assembled four non-redundant MAGs from morphologically distinct Trichodesmium colonies (tufts, dense and thin puffs). Trichodesmium thiebautii (puffs) and Trichodesmium erythraeum (tufts) were the dominant species within these morphotypes. While subspecies diversity is present for both T. thiebautii and T. erythraeum, a single T. thiebautii genotype comprised both thin and dense puff morphotypes, and we hypothesize that this phenotypic variation is likely attributed to gene regulation. Additionally, we found the rare non-diazotrophic clade IV and V genotypes, related to Trichodesmium nobis and Trichodesmium miru, respectively that likely occurred as single filaments. The hetR gene phylogeny further indicated that the genotype in clade IV could represent the species Trichodesmium contortum. Importantly, we show the presence of hetR paralogs in Trichodesmium, where two copies of the hetR gene were present within T. thiebautii genomes. This may lead to the overestimation of Trichodesmium diversity as one of the copies misidentified T. thiebautii as Trichodesmium aureum. Taken together, our results highlight the importance of re-assessing Trichodesmium taxonomy while showing the ability of genomics to capture the complex diversity and distribution of Trichodesmium populations.
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Affiliation(s)
- Coco Koedooder
- The Fredy and Nadine Herrmann Institute of Earth Sciences, Hebrew University of Jerusalem, Jerusalem, Israel
- The Interuniversity Institute for Marine Sciences in Eilat, Eilat, Israel
- Israel Oceanographic and Limnological Research, Haifa, Israel
- *Correspondence: Coco Koedooder,
| | - Etai Landou
- Mina and Everard Goodman Faculty of Life Sciences, Bar Ilan University, Ramat Gan, Israel
| | - Futing Zhang
- The Fredy and Nadine Herrmann Institute of Earth Sciences, Hebrew University of Jerusalem, Jerusalem, Israel
- The Interuniversity Institute for Marine Sciences in Eilat, Eilat, Israel
| | - Siyuan Wang
- The Fredy and Nadine Herrmann Institute of Earth Sciences, Hebrew University of Jerusalem, Jerusalem, Israel
- The Interuniversity Institute for Marine Sciences in Eilat, Eilat, Israel
| | - Subhajit Basu
- The Fredy and Nadine Herrmann Institute of Earth Sciences, Hebrew University of Jerusalem, Jerusalem, Israel
- The Interuniversity Institute for Marine Sciences in Eilat, Eilat, Israel
- Microsensor Research Group, Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Ilana Berman-Frank
- Department of Marine Biology, Leon H. Charney School of Marine Sciences, University of Haifa, Haifa, Israel
| | - Yeala Shaked
- The Fredy and Nadine Herrmann Institute of Earth Sciences, Hebrew University of Jerusalem, Jerusalem, Israel
- The Interuniversity Institute for Marine Sciences in Eilat, Eilat, Israel
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7
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Zhu Z, Meng R, Smith WO, Doan-Nhu H, Nguyen-Ngoc L, Jiang X. Bacterial Composition Associated With Giant Colonies of the Harmful Algal Species Phaeocystis globosa. Front Microbiol 2021; 12:737484. [PMID: 34721335 PMCID: PMC8555426 DOI: 10.3389/fmicb.2021.737484] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Accepted: 08/17/2021] [Indexed: 12/05/2022] Open
Abstract
The cosmopolitan algae Phaeocystis globosa forms harmful algal blooms frequently in a number of tropical and subtropical coastal regions in the past two decades. During the bloom, the giant colony, which is formed by P. globosa, is the dominant morphotype. However, the microenvironment and the microbial composition in the intracolonial fluid are poorly understood. Here, we used high-throughput 16S rRNA amplicon sequencing to examine the bacterial composition and predicted functions in intracolonial fluid. Compared with the bacterial consortia in ambient seawater, intracolonial fluids possessed the lower levels of microbial richness and diversity, implying selectivity of bacteria by the unique intracolonial microenvironment enclosed within the P. globosa polysaccharide envelope. The bacterial consortia in intracolonial fluid were dominated by Balneola (48.6% of total abundance) and Labrezia (28.5%). The bacteria and microbial function enriched in intracolonial fluid were involved in aromatic benzenoid compounds degradation, DMSP and DMS production and consumption, and antibacterial compounds synthesis. We suggest that the P. globosa colonial envelope allows for the formation of a specific microenvironment; thus, the unique microbial consortia inhabiting intracolonial fluid has close interaction with P. globosa cells, which may benefit colony development.
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Affiliation(s)
- Zhu Zhu
- School of Oceanography, Shanghai Jiao Tong University, Shanghai, China
| | - Rui Meng
- School of Oceanography, Shanghai Jiao Tong University, Shanghai, China
| | - Walker O Smith
- School of Oceanography, Shanghai Jiao Tong University, Shanghai, China
| | - Hai Doan-Nhu
- Vietnam Academy of Science and Technology, Institute of Oceanography, Nha Trang, Vietnam
| | - Lam Nguyen-Ngoc
- Vietnam Academy of Science and Technology, Institute of Oceanography, Nha Trang, Vietnam
| | - Xinjun Jiang
- School of Oceanography, Shanghai Jiao Tong University, Shanghai, China
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8
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Iron transport in cyanobacteria - from molecules to communities. Trends Microbiol 2021; 30:229-240. [PMID: 34175176 DOI: 10.1016/j.tim.2021.06.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 06/01/2021] [Accepted: 06/01/2021] [Indexed: 11/22/2022]
Abstract
Iron is an essential micronutrient for the ecologically important photoautotrophic cyanobacteria which are found across diverse aquatic environments. Low concentrations and poor bioavailability of certain iron species exert a strong control on cyanobacterial growth, affecting ecosystem structure and biogeochemical cycling. Here, we review the iron-acquisition pathways cyanobacteria utilize for overcoming these challenges. As the molecular details of cyanobacterial iron transport are being uncovered, an overall scheme of how cyanobacteria handle and exploit this scarce and redox-active micronutrient is emerging. Importantly, the range of biological solutions used by cyanobacteria to increase iron fluxes goes beyond transport and includes behavioral traits of colonial cyanobacteria and intricate cyanobacteria-bacteria interactions.
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9
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Wang S, Tang W, Delage E, Gifford S, Whitby H, González AG, Eveillard D, Planquette H, Cassar N. Investigating the microbial ecology of coastal hotspots of marine nitrogen fixation in the western North Atlantic. Sci Rep 2021; 11:5508. [PMID: 33750865 PMCID: PMC7943828 DOI: 10.1038/s41598-021-84969-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Accepted: 01/27/2021] [Indexed: 11/24/2022] Open
Abstract
Variation in the microbial cycling of nutrients and carbon in the ocean is an emergent property of complex planktonic communities. While recent findings have considerably expanded our understanding of the diversity and distribution of nitrogen (N2) fixing marine diazotrophs, knowledge gaps remain regarding ecological interactions between diazotrophs and other community members. Using quantitative 16S and 18S V4 rDNA amplicon sequencing, we surveyed eukaryotic and prokaryotic microbial communities from samples collected in August 2016 and 2017 across the Western North Atlantic. Leveraging and significantly expanding an earlier published 2015 molecular dataset, we examined microbial community structure and ecological co-occurrence relationships associated with intense hotspots of N2 fixation previously reported at sites off the Southern New England Shelf and Mid-Atlantic Bight. Overall, we observed a negative relationship between eukaryotic diversity and both N2 fixation and net community production (NCP). Maximum N2 fixation rates occurred at sites with high abundances of mixotrophic stramenopiles, notably Chrysophyceae. Network analysis revealed such stramenopiles to be keystone taxa alongside the haptophyte diazotroph host Braarudosphaera bigelowii and chlorophytes. Our findings highlight an intriguing relationship between marine stramenopiles and high N2 fixation coastal sites.
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Affiliation(s)
- Seaver Wang
- Division of Earth and Ocean Sciences, Duke University, Grainger Environment Hall, 9 Circuit Drive, Box 90328, Durham, NC, 27708, USA
| | - Weiyi Tang
- Department of Geosciences, Princeton University, Princeton, NJ, USA
| | - Erwan Delage
- LS2N, UMR 6004, CNRS, Université de Nantes, 44000, Nantes, France
| | - Scott Gifford
- Department of Marine Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Hannah Whitby
- Department of Earth, Ocean, and Ecological Sciences, School of Environmental Sciences, University of Liverpool, Liverpool, UK
| | - Aridane G González
- Instituto de Oceanografía y Cambio Global (IOCAG), Universidad de Las Palmas de Gran Canaria, ULPGC, Las Palmas, Spain.,Laboratoire des Sciences de l'Environnement Marin (LEMAR), Institut Universitaire Européen de la Mer (IUEM), Technopôle Brest-Iroise, 13 Plouzané, 29280, Locmaria-Plouzané, France
| | - Damien Eveillard
- LS2N, UMR 6004, CNRS, Université de Nantes, 44000, Nantes, France
| | - Hélène Planquette
- Laboratoire des Sciences de l'Environnement Marin (LEMAR), Institut Universitaire Européen de la Mer (IUEM), Technopôle Brest-Iroise, 13 Plouzané, 29280, Locmaria-Plouzané, France
| | - Nicolas Cassar
- Division of Earth and Ocean Sciences, Duke University, Grainger Environment Hall, 9 Circuit Drive, Box 90328, Durham, NC, 27708, USA. .,Laboratoire des Sciences de l'Environnement Marin (LEMAR), Institut Universitaire Européen de la Mer (IUEM), Technopôle Brest-Iroise, 13 Plouzané, 29280, Locmaria-Plouzané, France.
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10
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Distinct nitrogen cycling and steep chemical gradients in Trichodesmium colonies. ISME JOURNAL 2019; 14:399-412. [PMID: 31636364 PMCID: PMC6976679 DOI: 10.1038/s41396-019-0514-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 09/10/2019] [Accepted: 09/11/2019] [Indexed: 11/08/2022]
Abstract
Trichodesmium is an important dinitrogen (N2)-fixing cyanobacterium in marine ecosystems. Recent nucleic acid analyses indicate that Trichodesmium colonies with their diverse epibionts support various nitrogen (N) transformations beyond N2 fixation. However, rates of these transformations and concentration gradients of N compounds in Trichodesmium colonies remain largely unresolved. We combined isotope-tracer incubations, micro-profiling and numeric modelling to explore carbon fixation, N cycling processes as well as oxygen, ammonium and nitrate concentration gradients in individual field-sampled Trichodesmium colonies. Colonies were net-autotrophic, with carbon and N2 fixation occurring mostly during the day. Ten percent of the fixed N was released as ammonium after 12-h incubations. Nitrification was not detectable but nitrate consumption was high when nitrate was added. The consumed nitrate was partly reduced to ammonium, while denitrification was insignificant. Thus, the potential N transformation network was characterised by fixed N gain and recycling processes rather than denitrification. Oxygen concentrations within colonies were ~60-200% air-saturation. Moreover, our modelling predicted steep concentration gradients, with up to 6-fold higher ammonium concentrations, and nitrate depletion in the colony centre compared to the ambient seawater. These gradients created a chemically heterogeneous microenvironment, presumably facilitating diverse microbial metabolisms in millimetre-sized Trichodesmium colonies.
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11
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Basu S, Gledhill M, de Beer D, Prabhu Matondkar SG, Shaked Y. Colonies of marine cyanobacteria Trichodesmium interact with associated bacteria to acquire iron from dust. Commun Biol 2019; 2:284. [PMID: 31396564 PMCID: PMC6677733 DOI: 10.1038/s42003-019-0534-z] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Accepted: 07/05/2019] [Indexed: 11/08/2022] Open
Abstract
Iron (Fe) bioavailability limits phytoplankton growth in vast ocean regions. Iron-rich dust uplifted from deserts is transported in the atmosphere and deposited on the ocean surface. However, this dust is a poor source of iron for most phytoplankton since dust-bound Fe is poorly soluble in seawater and dust rapidly sinks out of the photic zone. An exception is Trichodesmium, a globally important, N2 fixing, colony forming, cyanobacterium, which efficiently captures and shuffles dust to its colony core. Trichodesmium and bacteria that reside within its colonies carry out diverse metabolic interactions. Here we show evidence for mutualistic interactions between Trichodesmium and associated bacteria for utilization of iron from dust, where bacteria promote dust dissolution by producing Fe-complexing molecules (siderophores) and Trichodesmium provides dust and optimal physical settings for dissolution and uptake. Our results demonstrate how intricate relationships between producers and consumers can influence productivity in the nutrient starved open ocean.
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Affiliation(s)
- Subhajit Basu
- The Fredy and Nadine Herrmann Institute of Earth Sciences, Hebrew University of Jerusalem, 91904 Jerusalem, Israel
- The Interuniversity Institute for Marine Sciences in Eilat, 88103 Eilat, Israel
| | - Martha Gledhill
- GEOMAR, Helmholtz Centre for Ocean Research, Wischhofstrasse 1-3, 24148 Kiel, Germany
| | - Dirk de Beer
- Max Planck Institute for Marine Microbiology (MPI Bremen), Celsiusstr 1, 28359 Bremen, Germany
| | | | - Yeala Shaked
- The Fredy and Nadine Herrmann Institute of Earth Sciences, Hebrew University of Jerusalem, 91904 Jerusalem, Israel
- The Interuniversity Institute for Marine Sciences in Eilat, 88103 Eilat, Israel
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12
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Frischkorn KR, Haley ST, Dyhrman ST. Coordinated gene expression between Trichodesmium and its microbiome over day-night cycles in the North Pacific Subtropical Gyre. ISME JOURNAL 2018; 12:997-1007. [PMID: 29382945 DOI: 10.1038/s41396-017-0041-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2017] [Revised: 10/03/2017] [Accepted: 12/16/2017] [Indexed: 11/09/2022]
Abstract
Trichodesmium is a widespread, N2 fixing marine cyanobacterium that drives inputs of newly fixed nitrogen and carbon into the oligotrophic ecosystems where it occurs. Colonies of Trichodesmium ubiquitously occur with heterotrophic bacteria that make up a diverse microbiome, and interactions within this Trichodesmium holobiont could influence the fate of fixed carbon and nitrogen. Metatranscriptome sequencing was performed on Trichodesmium colonies collected during high-frequency Lagrangian sampling in the North Pacific Subtropical Gyre (NPSG) to identify possible interactions between the Trichodesmium host and microbiome over day-night cycles. Here we show significantly coordinated patterns of gene expression between host and microbiome, many of which had significant day-night periodicity. The functions of the co-expressed genes suggested a suite of interactions within the holobiont linked to key resources including nitrogen, carbon, and iron. Evidence of microbiome reliance on Trichodesmium-derived vitamin B12 was also detected in co-expression patterns, highlighting a dependency that could shape holobiont community structure. Collectively, these patterns of expression suggest that biotic interactions could influence colony cycling of resources like nitrogen and vitamin B12, and decouple activities, like N2 fixation, from typical abiotic drivers of Trichodesmium physiological ecology.
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Affiliation(s)
- Kyle R Frischkorn
- Department of Earth and Environmental Sciences, Columbia University, New York, NY, 10025, USA.,Lamont-Doherty Earth Observatory, Palisades, NY, 10964, USA
| | - Sheean T Haley
- Lamont-Doherty Earth Observatory, Palisades, NY, 10964, USA
| | - Sonya T Dyhrman
- Department of Earth and Environmental Sciences, Columbia University, New York, NY, 10025, USA. .,Lamont-Doherty Earth Observatory, Palisades, NY, 10964, USA.
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