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.

Centre A lgatech Institute of Microbiology The Czech Academy of Sciences Trebon Czech Republic

Daniel K Inouye Center for Microbial Oceanography Research and Education University of Hawai'i at Manoa Honolulu HI USA

Department of Biology and Nordic Center for Earth Evolution University of Southern Denmark Odense M Denmark

Department of Earth System Science Stanford University Stanford CA USA

Department of Ecology Environment and Plant Sciences Stockholm University Stockholm Sweden

Department of Experimental Limnology IGB Leibniz Institute of Freshwater Ecology and Inland Fisheries Berlin Germany

Department of Isotope Biogeochemistry Helmholtz Centre for Environmental Research Leipzig Germany

Department of Marine Sciences University of Gothenburg Gothenburg Sweden

Department of Physics and Earth Sciences Jacobs University Bremen Bremen Germany

Max Planck Institute for Marine Microbiology Bremen Germany

Zobrazit více v PubMed

Sohm JA, Webb EA, Capone DG. Emerging patterns of marine nitrogen fixation. Nat Rev Microbiol. 2011;9:499–508. PubMed

Capone DG, Burns JA, Montoya JP, Subramaniam A, Mahaffey C, Gunderson T, et al. Nitrogen fixation by Trichodesmium spp.: an important source of new nitrogen to the tropical and subtropical North Atlantic Ocean. Glob Biogeochem Cycles. 2005;19:1–17.

Dore JE, Brum JR, Tupas LM, Karl DM. Seasonal and interannual variability in sources of nitrogen supporting export in the oligotrophic subtropical North Pacific Ocean. Limnol Oceanogr. 2002;47:1595–607.

Bonnet S, Berthelot H, Turk-Kubo K, Cornet-Barthaux V, Fawcett S, Berman-Frank I, et al. Diazotroph derived nitrogen supports diatom growth in the South West Pacific: A quantitative study using nanoSIMS. Limnol Oceanogr. 2016;61:1549–62.

Berthelot H, Bonnet S, Grosso O, Cornet V, Barani A. Transfer of diazotroph-derived nitrogen towards non-diazotrophic planktonic communities: a comparative study between Trichodesmium erythraeum, Crocosphaera watsonii and Cyanothece sp. Biogeosciences. 2016;13:4005–21.

Sipler RE, Bronk DA, Seitzinger SP, Lauck RJ, McGuinness LR, Kirkpatrick GJ, et al. Trichodesmium-derived dissolved organic matter is a source of nitrogen capable of supporting the growth of toxic red tide Karenia brevis. Mar Ecol Prog Ser. 2013;483:31–45.

Bonnet S, Baklouti M, Gimenez A, Berthelot H, Berman-Frank I. Biogeochemical and biological impacts of diazotroph blooms in a low-nutrient, low-chlorophyll ecosystem: synthesis from the VAHINE mesocosm experiment (New Caledonia) Biogeosciences. 2016;13:4461–79.

Karl D, Letelier R, Tupas L, Dore J, Christian J, Hebel D. The role of nitrogen fixation in biogeochemical cycling in the subtropical North Pacific Ocean. Nature. 1997;388:533–8.

Bar-Zeev E, Avishay I, Bidle KD, Berman-Frank I. Programmed cell death in the marine cyanobacterium Trichodesmium mediates carbon and nitrogen export. ISME J. 2013;7:2340–8. PubMed PMC

Janson S, Siddiqui PJA, Walsby AE, Romans KM, Carpenter EJ, Bergman B. Cytomorphological characterization of the planktonic diazotrophic cyanobacteria Trichodesmium spp. from the Indian Ocean and Caribbean and Sargasso Seas. J Phycol. 1995;31:463–77.

McKinna LIW. Three decades of ocean-color remote-sensing Trichodesmium spp. in the World’s oceans: a review. Prog Oceanogr. 2015;131:177–99.

Goering JJ, Dugdale RC, Menzel DW. Estimates of in situ rates of nitrogen uptake by Trichodesmium sp. in the Tropical Atlantic Ocean. Limnol Oceanogr. 1966;11:614–20.

Capone DG, Zehr JP, Paerl HW, Bergman B, Carpenter EJ. Trichodesmium, a globally significant marine cyanobacterium. Science. 1997;276:1221–9.

Coates CJ, Wyman M. A denitrifying community associated with a major, marine nitrogen fixer. Environ Microbiol. 2017;19:4978–92. PubMed

Gradoville MR, Crump BC, Letelier RM, Church MJ, White AE. Microbiome of Trichodesmium colonies from the North Pacific Subtropical Gyre. Front Microbiol. 2017;8:1122. PubMed PMC

Lee MD, Webb EA, Walworth NG, Fu F-X, Held NA, Saito MA, et al. Transcriptional activities of the microbial consortium living with the marine nitrogen-fixing cyanobacterium Trichodesmium reveal potential roles in community-level nitrogen cycling. Appl Environ Microbiol. 2018;84:e02026–17. PubMed PMC

Gruber N. Chapter 1—The marine nitrogen cycle: overview and challenges. In: Capone DG, Bronk DA, Mulholland MR, Carpenter EJ, editors. Nitrogen in the marine environment. 2nd ed. San Diego: Academic Press; 2008. p. 1–50.

Bronk Deborah A. Biogeochemistry of Marine Dissolved Organic Matter. 2002. Dynamics of DON; pp. 153–247.

Lam P, Kuypers MMM. Microbial nitrogen cycling processes in oxygen minimum zones. Ann Rev Mar Sci. 2011;3:317–45. PubMed

Thamdrup B. Novel pathways and organisms in global nitrogen cycling. Annu Rev Ecol Evol Syst. 2012;43:407–28.

Stief P, Kamp A, Thamdrup B, Glud RN. Anaerobic nitrogen turnover by sinking diatom aggregates at varying ambient oxygen levels. Front Microbiol. 2016;7:98. PubMed PMC

Klawonn I, Bonaglia S, Brüchert V, Ploug H. Aerobic and anaerobic nitrogen transformation processes in N2-fixing cyanobacterial aggregates. ISME J. 2015;9:1456–66. PubMed PMC

Eichner MJ, Klawonn I, Wilson ST, Littmann S, Whitehouse MJ, Church MJ, et al. Chemical microenvironments and single-cell carbon and nitrogen uptake in field-collected colonies of Trichodesmium under different pCO2. ISME J. 2017;11:1305–17. PubMed PMC

Paerl HW, Bebout BM. Direct measurement of O2-depleted microzones in marine Oscillatoria: relation to N2 fixation. Science. 1988;241:442–5. PubMed

Prufert-Bebout L, Paerl HW, Lassen C. Growth, nitrogen fixation, and spectral attenuation in cultivated Trichodesmium species. Appl Environ Microbiol. 1993;59:1367–75. PubMed PMC

Nausch M. Microbial activities on Trichodesmium colonies. Mar Ecol Prog Ser. 1996;141:173–81.

Capone DG, Ferrier MD, Carpenter EJ. Amino acid cycling in colonies of the planktonic marine cyanobacterium Trichodesmium thiebautii. Appl Environ Microbiol. 1994;60:3989–95. PubMed PMC

Mulholland MR, Bernhardt PW, Heil CA, Bronk DA, O’Neil JM. Nitrogen fixation and release of fixed nitrogen by Trichodesmium spp. in the Gulf of Mexico. Limnol Oceanogr. 2006;51:1762–76.

Glibert PM, Bronk DA. Release of dissolved organic nitrogen by marine diazotrophic cyanobacteria, Trichodesmium spp. Appl Environ Microbiol. 1994;60:3996–4000. PubMed PMC

Carpenter EJ, Bergman B, Dawson R, Siddiqui PJ, Söderbäck E, Capone DG. Glutamine synthetase and nitrogen cycling in colonies of the marine diazotrophic cyanobacteria Trichodesmium spp. Appl Environ Microbiol. 1992;58:3122–9. PubMed PMC

Seymour JR, Amin SA, Raina JB, Stocker R. Zooming in on the phycosphere: The ecological interface for phytoplankton-bacteria relationships. Nat Microbiol. 2017;2:17065. PubMed

Hmelo LR, Van Mooy BAS, Mincer TJ. Characterization of bacterial epibionts on the cyanobacterium Trichodesmium. Aquat Microb Ecol. 2012;67:1–14.

Rouco M, Haley ST, Dyhrman ST. Microbial diversity within the Trichodesmium holobiont. Environ Microbiol. 2016;18:5151–60. PubMed

Borstad GA, Borstad L. The Oscillatoria erythraea (Cyanophyta) community of associates. In: Stewart HB, editor. Cooperative Investigations of the Caribbean and Adjacent Regions-II. Rome: FAO Fisheries Reports (FAO); 1977, p. 51–57.

Paerl HW, Bebout BM, Prufert LE. Bacterial associations with marine Oscillatoria sp. (Trichodesmium sp.) populations: Ecophysiological implications. J Phycol. 1989;25:773–84.

O’Neil Judith M., Roman Michael R. Marine Pelagic Cyanobacteria: Trichodesmium and other Diazotrophs. Dordrecht: Springer Netherlands; 1992. Grazers and Associated Organisms of Trichodesmium; pp. 61–73.

Sheridan CC, Steinberg DK, Kling GW. The microbial and metazoan community associated with colonies of Trichodesmium spp.: a quantitative survey. J Plankton Res. 2002;24:913–22.

Frischkorn KR, Rouco M, Van Mooy BAS, Dyhrman ST. Epibionts dominate metabolic functional potential of Trichodesmium colonies from the oligotrophic ocean. ISME J. 2017;11:2090–101. PubMed PMC

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 J. 2018;12:997–1007. PubMed PMC

Hewson I, Paerl RW, Tripp HJ, Zehr JP, Karl DM. Metagenomic potential of microbial assemblages in the surface waters of the central Pacific Ocean tracks variability in oceanic habitat. Limnol Oceanogr. 2009;54:1981–94.

Lee MD, Walworth NG, McParland EL, Fu F-X, Mincer TJ, Levine NM, et al. The Trichodesmium consortium: conserved heterotrophic co-occurrence and genomic signatures of potential interactions. ISME J. 2017;11:1813–24. PubMed PMC

Hynes AM, Webb EA, Doney SC, Waterbury JB. Comparison of cultured Trichodesmium (Cyanophyceae) with species characterized from the field. J Phycol. 2012;48:196–210. PubMed

Klawonn I, Lavik G, Böning P, Marchant HK, Dekaezemacker J, Mohr W, et al. Simple approach for the preparation of 15-15N2-enriched water for nitrogen fixation assessments: evaluation, application and recommendations. Front Microbiol. 2015;6:769. PubMed PMC

Gordon LI, Jennings Jr. JC, Ross AA. A suggested protocol for continuous flow automated analysis of seawater nutrients using the Alpkem Flow Solution IV System. In: Chemical protocols used in the WOCE Hydrographic Program and Joint Global Ocean Flux Study. College of Oceanic and Atmospheric Sciences. Oregon: Oregon State University in Corvallis; 2001.

Hall GH. Measurement of nitrification rates in lake sediments: comparison of the nitrification inhibitors nitrapyrin and allylthiourea. Microb Ecol. 1984;10:25–36. PubMed

Jensen MM, Thamdrup B, Dalsgaard T. Effects of specific inhibitors on anammox and denitrification in marine sediments. Appl Environ Microbiol. 2007;73:3151–8. PubMed PMC

Ploug H, Grossart HP. Bacterial production and respiration in suspended aggregates—a matter of the incubation method. Aquat Microb Ecol. 1999;20:21–29.

Montoya JP, Voss M, Kähler P, Capone DG. A simple, high-precision, high-sensitivity tracer assay for N2 fixation. Appl Environ Microbiol. 1996;62:986–93. PubMed PMC

Walsby AE. The properties and buoyancy-providing role of gas vacuoles in Trichodesmium Ehrenberg. Br Phycol J. 1978;13:103–16.

Ploug H, Jørgensen BB. A net-jet flow system for mass transfer and microsensor studies of sinking aggregates. Mar Ecol Prog Ser. 1999;176:279–90.

Revsbech NP. An oxygen microelectrode with a guard cathode. Limnol Oceanogr. 1989;34:474–8.

Moradi N, Liu B, Iversen M, Kuypers MMM, Ploug H, Khalili A. A new mathematical model to explore microbial processes and their constraints in phytoplankton colonies and sinking marine aggregates. Sci Adv. 2018;4:eaat1991. PubMed PMC

Passow U. Transparent exopolymer particles (TEP) in aquatic environments. Prog Oceanogr. 2002;55:287–333.

Ploug H, Hietanen S, Kuparinen J. Diffusion and advection within and around sinking, porous diatom aggregates. Limnol Oceanogr. 2002;47:1129–36.

Fenchel T, Finlay BJ. Ecology and evolution in anoxic worlds. Oxford: Oxford University Press; 1995. p. 288.

Harrison WG, Harris LR, Irwin BD. The kinetics of nitrogen utilization in the oceanic mixed layer: nitrate and ammonium interactions at nanomolar concentrations. Limnol Oceanogr. 1996;41:16–32.

Liu B, Kindler K, Khalili A. Dynamic solute release from marine aggregates. Limnol Oceanogr Fluid Environ. 2012;2:109–20.

Eichner M, Thoms S, Rost B, Mohr W, Ahmerkamp S, Ploug H, et al. N2 fixation in free-floating filaments of Trichodesmium is higher than in transiently suboxic colony microenvironments. New Phytol. 2018;222:852–63. PubMed PMC

Ploug H, Adam B, Musat N, Kalvelage T, Lavik G, Wolf-Gladrow D, et al. Carbon, nitrogen and O2 fluxes associated with the cyanobacterium Nodularia spumigena in the Baltic Sea. ISME J. 2011;5:1549–58. PubMed PMC

Ploug H, Musat N, Adam B, Moraru CL, Lavik G, Vagner T, et al. Carbon and nitrogen fluxes associated with the cyanobacterium Aphanizomenon sp. in the Baltic Sea. ISME J. 2010;4:1215–23. PubMed

Seymour JR, Marcos, Stocker R. Resource patch formation and exploitation throughout the marine microbial food web. Am Nat. 2009;173:E15–29. PubMed

Ploug H, Stolte W, Jørgensen BB. Diffusive boundary layers of the colony-forming plankton alga Phaeocystis sp. - Implications for nutrient uptake and cellular growth. Limnol Oceanogr. 1999;44:1959–67.

Rodier M, Le Borgne R. Population dynamics and environmental conditions affecting Trichodesmium spp. (filamentous cyanobacteria) blooms in the south-west lagoon of New Caledonia. J Exp Mar Biol Ecol. 2008;358:20–32.

Mulholland MR, Capone DG. The nitrogen physiology of the marine N2-fixing cyanobacteria Trichodesmium spp. Trends Plant Sci. 2000;5:148–53. PubMed

Carpenter EJ. The tropical diazotrophic phytoplankter Trichodesmium: biological characteristics of two common species. Mar Ecol Prog Ser. 1993;95:295–304.

LaRoche J, Breitbarth E. Importance of the diazotrophs as a source of new nitrogen in the ocean. J Sea Res. 2005;53:67–91.

Caffin M, Berthelot H, Cornet-Barthaux V, Barani A, Bonnet S. Transfer of diazotroph-derived nitrogen to the planktonic food web across gradients of N2 fixation activity and diversity in the western tropical South Pacific Ocean. Biogeosciences. 2018;15:3795–810.

Karl David M., Letelier Ricardo, Hebel Dale V., Bird David F., Winn Christopher D. Marine Pelagic Cyanobacteria: Trichodesmium and other Diazotrophs. Dordrecht: Springer Netherlands; 1992. Trichodesmium Blooms and New Nitrogen in the North Pacific Gyre; pp. 219–237.

Suttle CA, Fuhrman JA, Capone DG. Rapid ammonium cycling and concentration-dependent partitioning of ammonium and phosphate: implications for carbon transfer in planktonic communities. Limnol Oceanogr. 1990;35:424–33.

Klawonn I, Bonaglia S, Whitehouse MJ, Littmann S, Tienken D, Kuypers MMM, et al. Untangling hidden nutrient dynamics: rapid ammonium cycling and single-cell ammonium assimilation in marine plankton communities. ISME J. 2019;13:1960–74. PubMed PMC

Mulholland MR, Capone D. Nitrogen fixation, uptake and metabolism in natural and cultured populations of Trichodesmium spp. Mar Ecol Prog Ser. 1999;188:33–49.

Raimbault P, Garcia N. Evidence for efficient regenerated production and dinitrogen fixation in nitrogen-deficient waters of the South Pacific Ocean: impact on new and export production estimates. Biogeosciences. 2008;5:323–38.

Martínez-Pérez C, Mohr W, Löscher CR, Dekaezemacker J, Littmann S, Yilmaz P, et al. The small unicellular diazotrophic symbiont, UCYN-A, is a key player in the marine nitrogen cycle. Nat Microbiol. 2016;1:16163. PubMed

Bergman B, Sandh G, Lin S, Larsson J, Carpenter EJ. Trichodesmium—a widespread marine cyanobacterium with unusual nitrogen fixation properties. FEMS Microbiol Rev. 2013;37:286–302. PubMed PMC

Fredriksson C, Bergman B. Ultrastructural characterisation of cells specialised for nitrogen fixation in a non-heterocystous cyanobacterium, Trichodesmium spp. Protoplasma. 1997;197:76–85.

Benavides M, Berthelot H, Duhamel S, Raimbault P, Bonnet S. Dissolved organic matter uptake by Trichodesmium in the Southwest Pacific. Sci Rep. 2017;7:41315. PubMed PMC

Karl David M., Bidigare Robert R., Church Matthew J., Dore John E., Letelier Ricardo M., Mahaffey Claire, Zehr Jonathan P. Nitrogen in the Marine Environment. 2008. The Nitrogen Cycle in the North Pacific Trades Biome; pp. 705–769.

Letelier RM, Karl DM. Role of Trichodesmium spp. in the productivity of the subtropical North Pacific Ocean. Mar Ecol Prog Ser. 1996;133:263–73.

Farnelid H, Turk-Kubo K, Ploug H, Ossolinski JE, Collins JR, Van Mooy BAS, et al. Diverse diazotrophs are present on sinking particles in the North Pacific Subtropical Gyre. ISME J. 2019;13:170–82. PubMed PMC

Santoro AE, Richter RA, Dupont CL. Planktonic marine archaea. Ann Rev Mar Sci. 2019;11:131–58. PubMed

Tuomainen JM, Hietanen S, Kuparinen J, Martikainen PJ, Servomaa K. Baltic Sea cyanobacterial bloom contains denitrification and nitrification genes, but has negligible denitrification activity. FEMS Microbiol Ecol. 2003;45:83–96. PubMed

Karl DM, Knauer GA, Martin JH, Ward BB. Bacterial chemolithotrophy in the ocean is associated with sinking particles. Nature. 1984;309:54–56.

Olson RJ. Differential photoinhibition of marine nitrifying bacteria: a possible mechanism for the formation of the primary nitrite maximum. J Mar Res. 1981;39:227–38.

Ward BB, Capone DG, Zehr JP. What’s new in the nitrogen cycle? Oceanography. 2007;20:101–9.

Wan XS, Sheng H-X, Dai M, Zhang Y, Shi D, Trull TW, et al. Ambient nitrate switches the ammonium consumption pathway in the euphotic ocean. Nat Commun. 2018;9:915. PubMed PMC

Takaya N, Catalan-Sakairi MAB, Sakaguchi Y, Kato I, Zhou Z, Shoun H. Aerobic denitrifying bacteria that produce low levels of nitrous oxide. Appl Environ Microbiol. 2003;69:3152–7. PubMed PMC

Wyman M, Hodgson S, Bird C. Denitrifying alphaproteobacteria from the Arabian Sea that express nosZ, the gene encoding nitrous oxide reductase, in oxic and suboxic waters. Appl Environ Microbiol. 2013;79:2670. PubMed PMC

Zumft WG. Cell biology and molecular basis of denitrification. Microbiol Mol Biol Rev. 1997;61:533–616. PubMed PMC

Ploug H. Cyanobacterial surface blooms formed by Aphanizomenon sp. and Nodularia spumigena in the Baltic Sea: small-scale fluxes, pH, and oxygen microenvironments. Limnol Oceanogr. 2008;53:914–21.

Ploug H, Bergkvist J. Oxygen diffusion limitation and ammonium production within sinking diatom aggregates under hypoxic and anoxic conditions. Mar Chem. 2015;176:142–9.

Ploug H, Grossart HP, Azam F, Jørgensen BB. Photosynthesis, respiration, and carbon turnover in sinking marine snow from surface waters of Southern California Bight: implications for the carbon cycle in the ocean. Mar Ecol Prog Ser. 1999;179:1–11.

Alldredge AL, Cohen Y. Can microscale chemical patches persist in the sea? Microelectrode study of marine snow, fecal pellets. Science. 1987;235:689–91. PubMed

Ploug H, Kühl M, Buchholz-Cleven B, Jørgensen BB. Anoxic aggregates—an ephemeral phenomenon in the pelagic environment? Aquat Microb Ecol. 1997;13:285–94.

Kalvelage T, Jensen MM, Contreras S, Revsbech NP, Lam P, Günter M, et al. Oxygen sensitivity of anammox and coupled N cycle processes in oxygen minimum zones. PLoS ONE. 2011;6:e29299. PubMed PMC

Smethie WM. Nutrient regeneration and denitrification in low oxygen fjords. Deep-Sea Res. 1987;34:983–1006.

Babbin AR, Keil RG, Devol AH, Ward BB. Organic matter stoichiometry, flux, and oxygen control nitrogen loss in the ocean. Science. 2014;344:406–8. PubMed

Dalsgaard T, Stewart FJ, Thamdrup B, De Brabandere L, Revsbech NP, Ulloa O, et al. Oxygen at nanomolar levels reversibly suppresses process rates and gene expression in anammox and denitrification in the oxygen minimum zone off Northern Chile. mBio. 2014;5:e01966–14. PubMed PMC

Zakem EJ, Follows MJ. A theoretical basis for a nanomolar critical oxygen concentration. Limnol Oceanogr. 2017;62:795–805.

Paerl HW, Pinckney JL. A mini-review of microbial consortia: their roles in aquatic production and biogeochemical cycling. Microb Ecol. 1996;31:225–47. PubMed

Tzubari Y, Magnezi L, Be’er A, Berman-Frank I. Iron and phosphorus deprivation induce sociality in the marine bloom-forming cyanobacterium Trichodesmium. ISME J. 2018;12:1682–93. PubMed PMC

Planktonic Aggregates as Hotspots for Heterotrophic Diazotrophy: The Plot Thickens