1
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Müller MN, Vicente Ferreira Junior A, Zanardi Lamardo E, Yogui GT, Flores Montes MDJ, Silva MA, Lima EJAC, Rojas LAV, Jannuzzi LGDS, Cunha MDGGDS, Melo PAMDC, Carvalho VPCD, Carneiro YMM, Carreira RDS, Araujo M, Santos LPDS. Finding the needle in a haystack: Evaluation of ecotoxicological effects along the continental shelf break during the Brazilian mysterious oil spill. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 357:124422. [PMID: 38914197 DOI: 10.1016/j.envpol.2024.124422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Revised: 06/01/2024] [Accepted: 06/20/2024] [Indexed: 06/26/2024]
Abstract
Oceanic oil spills present significant ecological risks that have the potential to contaminate extensive areas, including coastal regions. The occurrence of the 2019 oil spill event in Brazil resulted in over 3000 km of contaminated beaches and shorelines. While assessing the impact on benthic and beach ecosystems is relatively straightforward due to direct accessibility, evaluating the ecotoxicological effects of open ocean oil spills on the pelagic community is a complex task. Difficulties are associated with the logistical challenges of responding promptly and, in case of the Brazilian mysterious oil spill, to the subsurface propagation of the oil that impeded remote visual detection. An oceanographic expedition was conducted in order to detect and evaluate the impact of this oil spill event along the north-eastern Brazilian continental shelf. The pursuit of dissolved and dispersed oil compounds was accomplished by standard oceanographic methods including seawater polycyclic aromatic hydrocarbons (PAHs) analysis, biomass stable carbon isotope (δ13C), particulate organic carbon to particulate organic nitrogen (POC:PON) ratios, nutrient analysis and ecotoxicological bioassays using the naupliar phase of the copepod Tisbe biminiensis. Significant ecotoxicological effects, reducing naupliar development by 20-40 %, were indicated to be caused by the presence of dispersed oil in the open ocean. The heterogeneous distribution of oil droplets aggravated the direct detection and biochemical indicators for oil are presented and discussed. Our findings serve as a case study for identifying and tracing subsurface propagation of oil, demonstrating the feasibility of utilizing standard oceanographic and ecotoxicological methods to assess the impacts of oil spill events in the open ocean. Ultimately, it encourages the establishment of appropriate measures and responses regarding the liability and regulation of entities to be held accountable for oil spills in the marine environment.
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Affiliation(s)
- Marius Nils Müller
- Department of Oceanography, Federal University of Pernambuco, Recife, PE, 50670-901, Brazil; Macau Environmental Research Institute, Macau University of Science and Technology, Macau SAR, 999078, China.
| | | | - Eliete Zanardi Lamardo
- Department of Oceanography, Federal University of Pernambuco, Recife, PE, 50670-901, Brazil
| | - Gilvan Takeshi Yogui
- Department of Oceanography, Federal University of Pernambuco, Recife, PE, 50670-901, Brazil
| | | | - Marcus André Silva
- Department of Oceanography, Federal University of Pernambuco, Recife, PE, 50670-901, Brazil
| | | | | | | | | | | | | | | | - Renato da Silva Carreira
- Department of Chemistry, Pontifical Catholic University of Rio de Janeiro, Rio de Janeiro, RJ, 22451-900, Brazil
| | - Moacyr Araujo
- Department of Oceanography, Federal University of Pernambuco, Recife, PE, 50670-901, Brazil
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2
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Lees LE, Jordan SNZ, Bracken MES. Kelps may compensate for low nitrate availability by using regenerated forms of nitrogen, including urea and ammonium. JOURNAL OF PHYCOLOGY 2024; 60:768-777. [PMID: 38703050 DOI: 10.1111/jpy.13459] [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: 07/17/2023] [Revised: 04/05/2024] [Accepted: 04/10/2024] [Indexed: 05/06/2024]
Abstract
Nitrate, the form of nitrogen often associated with kelp growth, is typically low in summer during periods of high macroalgal growth. More ephemeral, regenerated forms of nitrogen, such as ammonium and urea, are much less studied as sources of nitrogen for kelps, despite the relatively high concentrations of regenerated nitrogen found in the Southern California Bight, where kelps are common. To assess how nitrogen uptake by kelps varies by species and nitrogen form in southern California, USA, we measured uptake rates of nitrate, ammonium, and urea by Macrocystis pyrifera and Eisenia arborea individuals from four regions characterized by differences in nitrogen availability-Orange County, San Pedro, eastern Santa Catalina Island, and western Santa Catalina Island-during the summers of 2021 and 2022. Seawater samples collected at each location showed that overall nitrogen availability was low, but ammonium and urea were often more abundant than nitrate. We also quantified the internal %nitrogen of each kelp blade collected, which was positively associated with ambient environmental nitrogen concentrations at the time of collection. We observed that both kelp species readily took up nitrate, ammonium, and urea, with M. pyrifera taking up nitrate and ammonium more efficiently than E. arborea. Urea uptake efficiency for both species increased as internal percent nitrogen decreased. Our results indicate that lesser-studied, more ephemeral forms of nitrogen can readily be taken up by these kelps, with possible upregulation of urea uptake as nitrogen availability declines.
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Affiliation(s)
- Lauren E Lees
- Department of Ecology and Evolutionary Biology, University of California, Irvine, California, USA
| | - Sydney N Z Jordan
- Department of Ecology and Evolutionary Biology, University of California, Irvine, California, USA
| | - Matthew E S Bracken
- Department of Ecology and Evolutionary Biology, University of California, Irvine, California, USA
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3
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Zhou W, Hao J, Guo Y, Zhao C, Zhang M, Zhang S, Han F. Revealing bioresponses of biofilm and flocs to salinity gradient in halophilic biofilm reactor. BIORESOURCE TECHNOLOGY 2024; 401:130727. [PMID: 38643952 DOI: 10.1016/j.biortech.2024.130727] [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: 03/01/2024] [Revised: 04/09/2024] [Accepted: 04/18/2024] [Indexed: 04/23/2024]
Abstract
Understanding the different biological responses to salinity gradient between coexisting biofilm and flocs is crucial for regulating the ecological function of biofilm system. This study investigated performance, dynamics, and community assembly of biofilm system under 3 %-7% salinity gradient. The removal efficiency of NH4+-N remained stable and exceeded 93 % at 3 %-6% salinity, but decreased to below 80 % at 7 % salinity. The elevated salinity promoted the synthesis of extracellular polymer substrates, inhibited microbial respiration, and significantly regulated the microbial community structure. Compared to flocs, biofilm exhibited greater species diversity and richer Nitrosomonas. It was found diffusion limitations dominated the microbial community assembly under the salinity gradient. And microbial network revealed positive interactions predominated the microbial relationships, designating norank Spirochaetaceae, unclassified Micrococcales, Corynebacterium, and Pusillimonas as keystone species. Moreover, distinct salinity preferences in nitrogen transformation-related genes were observed. This study can improve the understanding to the regulation of biofilm systems to salt stresses.
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Affiliation(s)
- Weizhi Zhou
- School of Civil Engineering, Shandong University, Jinan, Shandong 250002, China; School of Environmental Science and Engineering, Shandong University, Qingdao, Shandong, China
| | - Jie Hao
- School of Environmental Science and Engineering, Shandong University, Qingdao, Shandong 266000, China; School of Environmental Science and Engineering, Shandong University, Qingdao, Shandong, China
| | - Yiting Guo
- School of Civil Engineering, Shandong University, Jinan, Shandong 250002, China; School of Environmental Science and Engineering, Shandong University, Qingdao, Shandong, China
| | - Chuanfu Zhao
- School of Civil Engineering, Shandong University, Jinan, Shandong 250002, China; School of Environmental Science and Engineering, Shandong University, Qingdao, Shandong, China
| | - Mengru Zhang
- School of Civil Engineering, Shandong University, Jinan, Shandong 250002, China; School of Environmental Science and Engineering, Shandong University, Qingdao, Shandong, China
| | - Shuhui Zhang
- School of Civil Engineering, Shandong University, Jinan, Shandong 250002, China; School of Environmental Science and Engineering, Shandong University, Qingdao, Shandong, China
| | - Fei Han
- School of Civil Engineering, Shandong University, Jinan, Shandong 250002, China; School of Environmental Science and Engineering, Shandong University, Qingdao, Shandong, China.
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4
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Burr DJ, Drauschke J, Kanevche K, Kümmel S, Stryhanyuk H, Heberle J, Perfumo A, Elsaesser A. Stable Isotope Probing-nanoFTIR for Quantitation of Cellular Metabolism and Observation of Growth-Dependent Spectral Features. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024:e2400289. [PMID: 38708804 DOI: 10.1002/smll.202400289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2024] [Revised: 04/16/2024] [Indexed: 05/07/2024]
Abstract
This study utilizes nanoscale Fourier transform infrared spectroscopy (nanoFTIR) to perform stable isotope probing (SIP) on individual bacteria cells cultured in the presence of 13C-labelled glucose. SIP-nanoFTIR simultaneously quantifies single-cell metabolism through infrared spectroscopy and acquires cellular morphological information via atomic force microscopy. The redshift of the amide I peak corresponds to the isotopic enrichment of newly synthesized proteins. These observations of single-cell translational activity are comparable to those of conventional methods, examining bulk cell numbers. Observing cells cultured under conditions of limited carbon, SIP- nanoFTIR is used to identify environmentally-induced changes in metabolic heterogeneity and cellular morphology. Individuals outcompeting their neighboring cells will likely play a disproportionately large role in shaping population dynamics during adverse conditions or environmental fluctuations. Additionally, SIP-nanoFTIR enables the spectroscopic differentiation of specific cellular growth phases. During cellular replication, subcellular isotope distribution becomes more homogenous, which is reflected in the spectroscopic features dependent on the extent of 13C-13C mode coupling or to specific isotopic symmetries within protein secondary structures. As SIP-nanoFTIR captures single-cell metabolism, environmentally-induced cellular processes, and subcellular isotope localization, this technique offers widespread applications across a variety of disciplines including microbial ecology, biophysics, biopharmaceuticals, medicinal science, and cancer research.
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Affiliation(s)
- David J Burr
- Department of Physics, Experimental Biophysics and Space Sciences, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
| | - Janina Drauschke
- Department of Physics, Experimental Biophysics and Space Sciences, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
| | - Katerina Kanevche
- Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
- Department of Chemistry, Princeton University, Princeton, NJ, 08544, USA
| | - Steffen Kümmel
- Department of Technical Biogeochemistry, Helmholtz Centre for Environmental Research - UFZ, Permoserstraße 15, 04318, Leipzig, Germany
| | - Hryhoriy Stryhanyuk
- Department of Technical Biogeochemistry, Helmholtz Centre for Environmental Research - UFZ, Permoserstraße 15, 04318, Leipzig, Germany
| | - Joachim Heberle
- Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
| | - Amedea Perfumo
- Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
- Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Polar Terrestrial Environmental Systems, Telegrafenberg, 14473, Potsdam, Germany
| | - Andreas Elsaesser
- Department of Physics, Experimental Biophysics and Space Sciences, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
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5
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Stenow R, Robertson EK, Whitehouse MJ, Ploug H. Single cell dynamics and nitrogen transformations in the chain forming diatom Chaetoceros affinis. THE ISME JOURNAL 2023; 17:2070-2078. [PMID: 37723340 PMCID: PMC10579250 DOI: 10.1038/s41396-023-01511-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Revised: 09/01/2023] [Accepted: 09/04/2023] [Indexed: 09/20/2023]
Abstract
Colony formation in phytoplankton is often considered a disadvantage during nutrient limitation in aquatic systems. Using stable isotopic tracers combined with secondary ion mass spectrometry (SIMS), we unravel cell-specific activities of a chain-forming diatom and interactions with attached bacteria. The uptake of 13C-bicarbonate and15N-nitrate or 15N-ammonium was studied in Chaetoceros affinis during the stationary growth phase. Low cell-to-cell variance of 13C-bicarbonate and 15N-nitrate assimilation within diatom chains prevailed during the early stationary phase. Up to 5% of freshly assimilated 13C and 15N was detected in attached bacteria within 12 h and supported bacterial C- and N-growth rates up to 0.026 h-1. During the mid-stationary phase, diatom chain-length decreased and 13C and 15N-nitrate assimilation was significantly higher in solitary cells as compared to that in chain cells. During the late stationary phase, nitrate assimilation ceased and ammonium assimilation balanced C fixation. At this stage, we observed highly active cells neighboring inactive cells within the same chain. In N-limited regimes, bacterial remineralization of N and the short diffusion distance between neighbors in chains may support surviving cells. This combination of "microbial gardening" and nutrient transfer within diatom chains represents a strategy which challenges current paradigms of nutrient fluxes in plankton communities.
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Affiliation(s)
- Rickard Stenow
- Department of Marine Sciences, University of Gothenburg, Box 461, SE, 405 30, Gothenburg, Sweden.
| | - Elizabeth K Robertson
- Department of Marine Sciences, University of Gothenburg, Box 461, SE, 405 30, Gothenburg, Sweden
| | - Martin J Whitehouse
- Swedish Museum of Natural History, Box 50 007, SE, 104 05, Stockholm, Sweden
| | - Helle Ploug
- Department of Marine Sciences, University of Gothenburg, Box 461, SE, 405 30, Gothenburg, Sweden
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6
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Chien CT, Pahlow M, Schartau M, Li N, Oschlies A. Effects of phytoplankton physiology on global ocean biogeochemistry and climate. SCIENCE ADVANCES 2023; 9:eadg1725. [PMID: 37494440 PMCID: PMC10371029 DOI: 10.1126/sciadv.adg1725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Accepted: 06/22/2023] [Indexed: 07/28/2023]
Abstract
The similarity of the average ratios of nitrogen (N) and phosphorus (P) in marine dissolved inorganic and particulate organic matter, dN:P and pN:P, respectively, indicates tight links between those pools in the world ocean. Here, we analyze this linkage by varying phytoplankton N and P subsistence quotas in an optimality-based ecosystem model coupled to an Earth system model. The analysis of our ensemble of simulations discloses various feedbacks between changes in the N and P quotas, N2 fixation, and denitrification that weaken the often-hypothesized tight coupling between dN:P and pN:P. We demonstrate the importance of particulate N:C and P:C ratios for regulating dN:P on the global scale, with marine oxygen level being an important control. Our analysis provides further insight into the potential interdependence of phytoplankton physiology and global climate conditions.
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Affiliation(s)
- Chia-Te Chien
- GEOMAR Helmholtz Centre for Ocean Research Kiel, Düsternbrooker Weg 20, 24105 Kiel, Germany
| | - Markus Pahlow
- GEOMAR Helmholtz Centre for Ocean Research Kiel, Düsternbrooker Weg 20, 24105 Kiel, Germany
| | - Markus Schartau
- GEOMAR Helmholtz Centre for Ocean Research Kiel, Düsternbrooker Weg 20, 24105 Kiel, Germany
| | - Na Li
- GEOMAR Helmholtz Centre for Ocean Research Kiel, Düsternbrooker Weg 20, 24105 Kiel, Germany
| | - Andreas Oschlies
- GEOMAR Helmholtz Centre for Ocean Research Kiel, Düsternbrooker Weg 20, 24105 Kiel, Germany
- Kiel University, 24118 Kiel, Germany
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7
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Arandia-Gorostidi N, Parada AE, Dekas AE. Single-cell view of deep-sea microbial activity and intracommunity heterogeneity. THE ISME JOURNAL 2023; 17:59-69. [PMID: 36202927 PMCID: PMC9750969 DOI: 10.1038/s41396-022-01324-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 09/08/2022] [Accepted: 09/12/2022] [Indexed: 12/15/2022]
Abstract
Microbial activity in the deep sea is cumulatively important for global elemental cycling yet is difficult to quantify and characterize due to low cell density and slow growth. Here, we investigated microbial activity off the California coast, 50-4000 m water depth, using sensitive single-cell measurements of stable-isotope uptake and nucleic acid sequencing. We observed the highest yet reported proportion of active cells in the bathypelagic (up to 78%) and calculated that deep-sea cells (200-4000 m) are responsible for up to 34% of total microbial biomass synthesis in the water column. More cells assimilated nitrogen derived from amino acids than ammonium, and at higher rates. Nitrogen was assimilated preferentially to carbon from amino acids in surface waters, while the reverse was true at depth. We introduce and apply the Gini coefficient, an established equality metric in economics, to quantify intracommunity heterogeneity in microbial anabolic activity. We found that heterogeneity increased with water depth, suggesting a minority of cells contribute disproportionately to total activity in the deep sea. This observation was supported by higher RNA/DNA ratios for low abundance taxa at depth. Intracommunity activity heterogeneity is a fundamental and rarely measured ecosystem parameter and may have implications for community function and resilience.
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Affiliation(s)
| | - A E Parada
- Department of Earth System Science, Stanford University, Stanford, CA, USA
| | - A E Dekas
- Department of Earth System Science, Stanford University, Stanford, CA, USA.
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8
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Han F, Zhou W. Nitrogen recovery from wastewater by microbial assimilation - A review. BIORESOURCE TECHNOLOGY 2022; 363:127933. [PMID: 36100188 DOI: 10.1016/j.biortech.2022.127933] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 09/03/2022] [Accepted: 09/06/2022] [Indexed: 06/15/2023]
Abstract
The increased nitrogen (N) input with low utilization rate in artificial N management has led to massive reactive N (Nr) flows, putting the Earth in a high-risk state. It is essential to recover and recycle Nr during or after Nr removal from wastewater to reduce N input while simultaneously mitigate Nr pollution in addressing the N stress. However, mechanisms for efficient Nr recovery during or after Nr removal remain unclear. Here, the occurrence of N risk and progress in wastewater treatment in recent years as well as challenges of the current technologies for N recovery from wastewater were reviewed. Through analyzing N conversion fluxes in biogeochemical N-cycling networks, microbial N assimilation through photosynthetic and heterotrophic microorganisms was highlighted as promising alternative for synergistic N removal and recovery in wastewater treatment. In addition, the prospects and gaps of Nr recovery from wastewater through microbial assimilation are discussed.
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Affiliation(s)
- Fei Han
- School of Environmental Science and Engineering, Shandong University, Qingdao, Shandong 266000, China
| | - Weizhi Zhou
- School of Civil Engineering, Shandong University, Jinan, Shandong 250002, China.
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9
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Zufia JA, Legrand C, Farnelid H. Seasonal dynamics in picocyanobacterial abundance and clade composition at coastal and offshore stations in the Baltic Sea. Sci Rep 2022; 12:14330. [PMID: 35995823 PMCID: PMC9395346 DOI: 10.1038/s41598-022-18454-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Accepted: 08/11/2022] [Indexed: 11/11/2022] Open
Abstract
Picocyanobacteria (< 2 µm in diameter) are significant contributors to total phytoplankton biomass. Due to the high diversity within this group, their seasonal dynamics and relationship with environmental parameters, especially in brackish waters, are largely unknown. In this study, the abundance and community composition of phycoerythrin rich picocyanobacteria (PE-SYN) and phycocyanin rich picocyanobacteria (PC-SYN) were monitored at a coastal (K-station) and at an offshore station (LMO; ~ 10 km from land) in the Baltic Sea over three years (2018–2020). Cell abundances of picocyanobacteria correlated positively to temperature and negatively to nitrate (NO3) concentration. While PE-SYN abundance correlated to the presence of nitrogen fixers, PC-SYN abundance was linked to stratification/shallow waters. The picocyanobacterial targeted amplicon sequencing revealed an unprecedented diversity of 2169 picocyanobacterial amplicons sequence variants (ASVs). A unique assemblage of distinct picocyanobacterial clades across seasons was identified. Clade A/B dominated the picocyanobacterial community, except during summer when low NO3, high phosphate (PO4) concentrations and warm temperatures promoted S5.2 dominance. This study, providing multiyear data, links picocyanobacterial populations to environmental parameters. The difference in the response of the two functional groups and clades underscore the need for further high-resolution studies to understand their role in the ecosystem.
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Affiliation(s)
- Javier Alegria Zufia
- Department of Biology and Environmental Science, Centre for Ecology and Evolution in Microbial Model Systems (EEMiS), Linnaeus University, Kalmar, Sweden
| | - Catherine Legrand
- Department of Biology and Environmental Science, Centre for Ecology and Evolution in Microbial Model Systems (EEMiS), Linnaeus University, Kalmar, Sweden.,School of Business, Innovation and Sustainability, Halmstad University, Halmstad, Sweden
| | - Hanna Farnelid
- Department of Biology and Environmental Science, Centre for Ecology and Evolution in Microbial Model Systems (EEMiS), Linnaeus University, Kalmar, Sweden.
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10
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Schön ME, Martijn J, Vosseberg J, Köstlbacher S, Ettema TJG. The evolutionary origin of host association in the Rickettsiales. Nat Microbiol 2022; 7:1189-1199. [PMID: 35798888 PMCID: PMC9352585 DOI: 10.1038/s41564-022-01169-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Accepted: 05/30/2022] [Indexed: 12/14/2022]
Abstract
The evolution of obligate host-association of bacterial symbionts and pathogens remains poorly understood. The Rickettsiales are an alphaproteobacterial order of obligate endosymbionts and parasites that infect a wide variety of eukaryotic hosts, including humans, livestock, insects and protists. Induced by their host-associated lifestyle, Rickettsiales genomes have undergone reductive evolution, leading to small, AT-rich genomes with limited metabolic capacities. Here we uncover eleven deep-branching alphaproteobacterial metagenome assembled genomes from aquatic environments, including data from the Tara Oceans initiative and other publicly available datasets, distributed over three previously undescribed Rickettsiales-related clades. Phylogenomic analyses reveal that two of these clades, Mitibacteraceae and Athabascaceae, branch sister to all previously sampled Rickettsiales. The third clade, Gamibacteraceae, branch sister to the recently identified ectosymbiotic ‘Candidatus Deianiraea vastatrix’. Comparative analyses indicate that the gene complement of Mitibacteraceae and Athabascaceae is reminiscent of that of free-living and biofilm-associated bacteria. Ancestral genome content reconstruction across the Rickettsiales species tree further suggests that the evolution of host association in Rickettsiales was a gradual process that may have involved the repurposing of a type IV secretion system. Phylogenomic analyses reveal novel environmental clades of Rickettsiales providing insights into their evolution from free-living to host-associated lifestyle.
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Affiliation(s)
- Max E Schön
- Department of Cell and Molecular Biology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Joran Martijn
- Department of Cell and Molecular Biology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden.,Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden.,Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Canada
| | - Julian Vosseberg
- Department of Cell and Molecular Biology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden.,Theoretical Biology and Bioinformatics, Department of Biology, Utrecht University, Utrecht, The Netherlands
| | - Stephan Köstlbacher
- Laboratory of Microbiology, Wageningen University and Research, Wageningen, The Netherlands
| | - Thijs J G Ettema
- Department of Cell and Molecular Biology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden. .,Laboratory of Microbiology, Wageningen University and Research, Wageningen, The Netherlands.
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11
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Wang J, Tang X, Mo Z, Mao Y. Metagenome-Assembled Genomes From Pyropia haitanensis Microbiome Provide Insights Into the Potential Metabolic Functions to the Seaweed. Front Microbiol 2022; 13:857901. [PMID: 35401438 PMCID: PMC8984609 DOI: 10.3389/fmicb.2022.857901] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Accepted: 02/28/2022] [Indexed: 12/24/2022] Open
Abstract
Pyropia is an economically important edible red alga worldwide. The aquaculture industry and Pyropia production have grown considerably in recent decades. Microbial communities inhabit the algal surface and produce a variety of compounds that can influence host adaptation. Previous studies on the Pyropia microbiome were focused on the microbial components or the function of specific microbial lineages, which frequently exclude metabolic information and contained only a small fraction of the overall community. Here, we performed a genome-centric analysis to study the metabolic potential of the Pyropia haitanensis phycosphere bacteria. We reconstructed 202 unique metagenome-assembled genomes (MAGs) comprising all major taxa present within the P. haitanensis microbiome. The addition of MAGs to the genome tree containing all publicly available Pyropia-associated microorganisms increased the phylogenetic diversity by 50% within the bacteria. Metabolic reconstruction of the MAGs showed functional redundancy across taxa for pathways including nitrate reduction, taurine metabolism, organophosphorus, and 1-aminocyclopropane-1-carboxylate degradation, auxin, and vitamin B12 synthesis. Some microbial functions, such as auxin and vitamin B12 synthesis, that were previously assigned to a few Pyropia-associated microorganisms were distributed across the diverse epiphytic taxa. Other metabolic pathways, such as ammonia oxidation, denitrification, and sulfide oxidation, were confined to specific keystone taxa.
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Affiliation(s)
- Junhao Wang
- Key Laboratory of Marine Genetics and Breeding (Ministry of Education), College of Marine Life Sciences, Ocean University of China, Qingdao, China
| | - Xianghai Tang
- Key Laboratory of Marine Genetics and Breeding (Ministry of Education), College of Marine Life Sciences, Ocean University of China, Qingdao, China
| | - Zhaolan Mo
- Key Laboratory of Marine Genetics and Breeding (Ministry of Education), College of Marine Life Sciences, Ocean University of China, Qingdao, China
- Key Laboratory of Tropical Aquatic Germplasm of Hainan Province, Sanya Oceanographic Institution, Ocean University of China, Sanya, China
| | - Yunxiang Mao
- Key Laboratory of Utilization and Conservation of Tropical Marine Bioresource (Ministry of Education), College of Fisheries and Life Sciences, Hainan Tropical Ocean University, Sanya, China
- Yazhou Bay Innovation Research Institute, Hainan Tropical Ocean University, Sanya, China
- Key Laboratory for Conservation and Utilization of Tropical Marine Fishery Resources of Hainan Province, Hainan Tropical Ocean University, Sanya, China
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12
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Alegria Zufia J, Farnelid H, Legrand C. Seasonality of Coastal Picophytoplankton Growth, Nutrient Limitation, and Biomass Contribution. Front Microbiol 2021; 12:786590. [PMID: 34938282 PMCID: PMC8685431 DOI: 10.3389/fmicb.2021.786590] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 11/08/2021] [Indexed: 11/13/2022] Open
Abstract
Picophytoplankton in the Baltic Sea includes the simplest unicellular cyanoprokaryotes (Synechococcus/Cyanobium) and photosynthetic picoeukaryotes (PPE). Picophytoplankton are thought to be a key component of the phytoplankton community, but their seasonal dynamics and relationships with nutrients and temperature are largely unknown. We monitored pico- and larger phytoplankton at a coastal site in Kalmar Sound (K-Station) weekly during 2018. Among the cyanoprokaryotes, phycoerythrin-rich picocyanobacteria (PE-rich) dominated in spring and summer while phycocyanin-rich picocyanobacteria (PC-rich) dominated during autumn. PE-rich and PC-rich abundances peaked during summer (1.1 × 105 and 2.0 × 105 cells mL–1) while PPE reached highest abundances in spring (1.1 × 105 cells mL–1). PPE was the main contributor to the total phytoplankton biomass (up to 73%). To assess nutrient limitation, bioassays with combinations of nitrogen (NO3 or NH4) and phosphorus additions were performed. PE-rich and PC-rich growth was mainly limited by nitrogen, with a preference for NH4 at >15°C. The three groups had distinct seasonal dynamics and different temperature ranges: 10°C and 17–19°C for PE-rich, 13–16°C for PC-rich and 11–15°C for PPE. We conclude that picophytoplankton contribute significantly to the carbon cycle in the coastal Baltic Sea and underscore the importance of investigating populations to assess the consequences of the combination of high temperature and NH4 in a future climate.
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Affiliation(s)
- Javier Alegria Zufia
- Marine Phytoplankton Ecology and Applications Laboratory (MPEA), Department of Biology and Environmental Science, Centre for Ecology and Evolution in Microbial Model Systems (EEMiS), Linnaeus University, Kalmar, Sweden
| | - Hanna Farnelid
- Marine Phytoplankton Ecology and Applications Laboratory (MPEA), Department of Biology and Environmental Science, Centre for Ecology and Evolution in Microbial Model Systems (EEMiS), Linnaeus University, Kalmar, Sweden
| | - Catherine Legrand
- Marine Phytoplankton Ecology and Applications Laboratory (MPEA), Department of Biology and Environmental Science, Centre for Ecology and Evolution in Microbial Model Systems (EEMiS), Linnaeus University, Kalmar, Sweden.,School of Business, Innovation and Sustainability, Halmstad University, Halmstad, Sweden
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13
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Zhang M, Han F, Li Y, Liu Z, Chen H, Li Z, Li Q, Zhou W. Nitrogen recovery by a halophilic ammonium-assimilating microbiome: A new strategy for saline wastewater treatment. WATER RESEARCH 2021; 207:117832. [PMID: 34781183 DOI: 10.1016/j.watres.2021.117832] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 10/15/2021] [Accepted: 10/31/2021] [Indexed: 05/12/2023]
Abstract
Wastewater with high salinity is one of the major challenges for conventional wastewater treatment. Although nitrogen management is vital for wastewater treatment, efficient strategies for nitrogen recovery and removal from saline wastewater remain challenging. Here we propose microbial ammonium assimilation to achieve efficient nitrogen removal and recovery into biomass from saline wastewater without gaseous nitrogen release opposite to the conventional wastewater treatment, . We find one marine bacterium Psychrobacter aquimaris A4N01 with the ability to form sedimentary granular biofilms that can be engineered to construct an efficient ammonium-assimilating microbiome followed the bottom-up design. We demonstrate that the microbiome removes ammonium through assimilation without reactive nitrogen intermediates and gaseous nitrogen emission, according to the functional gene abundance and nitrogen balance. More than 80% of ammonium, total nitrogen and total phosphorus are removed and recovered into biomass, with more than 98% of COD removed from saline wastewater. As one prototypic microbe to form ammonium-assimilating biofilms, Psychrobacter aquimaris A4N01 plays key role in nutrient metabolism and microbiome construction. We stress that ammonium assimilation with a clear and short pathway is a promising method in future saline wastewater treatment and sustainable nitrogen management.
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Affiliation(s)
- Mengru Zhang
- School of Environmental Science and Engineering, Shandong University, 250100 Jinan, China
| | - Fei Han
- School of Environmental Science and Engineering, Shandong University, 250100 Jinan, China
| | - Yuke Li
- Department of Water Management, Faculty of Civil Engineering and Geosciences, Delft University of Technology, Stevinweg 1, 2628 CN Delft, The Netherlands
| | - Zhe Liu
- School of Environmental Science and Engineering, Shandong University, 250100 Jinan, China
| | - Hao Chen
- School of Environmental Science and Engineering, Shandong University, 250100 Jinan, China
| | - Zhe Li
- School of Civil Engineering, Shandong University, 250061 Jinan, China
| | - Qian Li
- School of Environmental Science and Engineering, Shandong University, 250100 Jinan, China
| | - Weizhi Zhou
- School of Civil Engineering, Shandong University, 250061 Jinan, China.
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14
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Cryptic Constituents: The Paradox of High Flux–Low Concentration Components of Aquatic Ecosystems. WATER 2021. [DOI: 10.3390/w13162301] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The interface between terrestrial ecosystems and inland waters is an important link in the global carbon cycle. However, the extent to which allochthonous organic matter entering freshwater systems plays a major role in microbial and higher-trophic-level processes is under debate. Human perturbations can alter fluxes of terrestrial carbon to aquatic environments in complex ways. The biomass and production of aquatic microbes are traditionally thought to be resource limited via stoichiometric constraints such as nutrient ratios or the carbon standing stock at a given timepoint. Low concentrations of a particular constituent, however, can be strong evidence of its importance in food webs. High fluxes of a constituent are often associated with low concentrations due to high uptake rates, particularly in aquatic food webs. A focus on biomass rather than turnover can lead investigators to misconstrue dissolved organic carbon use by bacteria. By combining tracer methods with mass balance calculations, we reveal hidden patterns in aquatic ecosystems that emphasize fluxes, turnover rates, and molecular interactions. We suggest that this approach will improve forecasts of aquatic ecosystem responses to warming or altered nitrogen usage.
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15
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Cho C, Schwarz JP, Perring AE, Lamb KD, Kondo Y, Park JU, Park DH, Shim K, Park JS, Park RJ, Lee M, Song CK, Kim SW. Light-absorption enhancement of black carbon in the Asian outflow inferred from airborne SP2 and in-situ measurements during KORUS-AQ. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 773:145531. [PMID: 33582332 DOI: 10.1016/j.scitotenv.2021.145531] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 01/21/2021] [Accepted: 01/26/2021] [Indexed: 06/12/2023]
Abstract
We investigated the changes in the size distribution, coating thickness, and mass absorption cross-section (MAC) of black carbon (BC) with aging and estimated the light absorption enhancement (Eabs) in the Asian outflow from airborne in-situ measurements during 2016 KORUS-AQ campaign. The BC number concentration decreased, but mass mean diameter increased with increasing altitude in the West Coast (WC) and Seoul Metropolitan Area (SMA), reflecting the contrast between freshly emitted BC-containing particles at the surface and more aged aerosol associated with aggregation during vertical mixing and transport. Contradistinctively, BC number and mass size distributions were relatively invariant with altitude over the Yellow Sea (YS) because sufficiently aged BC from eastern China were horizontally transported to all altitudes over the YS, and there are no significant sources at the surface. The averaged inferred MAC of refractory BC in three regions reflecting differences in their size distributions increased to 9.8 ± 1.0 m2 g-1 (YS), 9.3 ± 0.9 m2 g-1 (WC), and 8.2 ± 0.9 m2 g-1 (SMA) as BC coating thickness increased from 20 nm to 120 nm. The absorption coefficient of BC calculated from the coating thickness and MAC were highly correlated with the filter-based absorption measurements with the slope of 1.16 and R2 of 0.96 at 550 nm, revealing that the thickly coated BC had a large MAC and absorption coefficient. The Eabs due to the inferred coatings was estimated as 1.0-1.6, which was about 30% lower than those from climate models and laboratory experiments, suggesting that the increase in the BC absorption by the coatings in the Asian outflow is not as large as calculated in the previous studies. Organics contributed to the largest Eabs accounting for 69% (YS), 61% (WC), and 64% (SMA). This implies that organics are largely responsible for the lensing effect of BC rather than sulfates in the Asian outflow.
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Affiliation(s)
- Chaeyoon Cho
- School of Earth and Environmental Sciences, Seoul National University, Seoul 08826, Republic of Korea
| | - Joshua P Schwarz
- NOAA Earth System Research Laboratory (ESRL), Chemical Sciences Division, Boulder, CO 80305, USA
| | - Anne E Perring
- NOAA Earth System Research Laboratory (ESRL), Chemical Sciences Division, Boulder, CO 80305, USA
| | - Kara D Lamb
- NOAA Earth System Research Laboratory (ESRL), Chemical Sciences Division, Boulder, CO 80305, USA; Cooperative Institute for Research in the Environmental Sciences (CIRES), University of Colorado, Boulder, CO 80309, USA
| | - Yutaka Kondo
- National Institute for Polar Research, Tachikawa, Tokyo 190-8518, Japan
| | - Jong-Uk Park
- School of Earth and Environmental Sciences, Seoul National University, Seoul 08826, Republic of Korea
| | - Do-Hyeon Park
- School of Earth and Environmental Sciences, Seoul National University, Seoul 08826, Republic of Korea
| | - Kyuseok Shim
- School of Earth and Environmental Sciences, Seoul National University, Seoul 08826, Republic of Korea
| | - Jin-Soo Park
- National Institute of Environmental Research, Incheon 22689, Republic of Korea
| | - Rokjin J Park
- School of Earth and Environmental Sciences, Seoul National University, Seoul 08826, Republic of Korea
| | - Meehye Lee
- Department of Earth and Environmental Sciences, Korea University, Seoul 02841, Republic of Korea
| | - Chang-Keun Song
- School of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea
| | - Sang-Woo Kim
- School of Earth and Environmental Sciences, Seoul National University, Seoul 08826, Republic of Korea.
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Characterizing the "fungal shunt": Parasitic fungi on diatoms affect carbon flow and bacterial communities in aquatic microbial food webs. Proc Natl Acad Sci U S A 2021; 118:2102225118. [PMID: 34074785 PMCID: PMC8201943 DOI: 10.1073/pnas.2102225118] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Planktonic microorganisms interact with each other in multifarious ways, ultimately catalyzing the flow of carbon and energy in diverse aquatic environments. However, crucial links associated with eukaryotic microparasites are still overlooked in planktonic networks. We addressed such links by studying cryptic interactions between parasitic fungi, phytoplankton, and bacteria using a model pathosystem. Our results demonstrate that parasitic fungi profoundly modified microbial interactions through several mechanisms (e.g., transferring photosynthetic carbon to infecting fungi, stimulating bacterial colonization on phytoplankton cells, and altering the community composition of bacteria and their acquisition of photosynthetic carbon). Hence, fungal microparasites can substantially shape the microbially mediated carbon flow at the base of aquatic food webs and should be considered as crucial members within plankton communities. Microbial interactions in aquatic environments profoundly affect global biogeochemical cycles, but the role of microparasites has been largely overlooked. Using a model pathosystem, we studied hitherto cryptic interactions between microparasitic fungi (chytrid Rhizophydiales), their diatom host Asterionella, and cell-associated and free-living bacteria. We analyzed the effect of fungal infections on microbial abundances, bacterial taxonomy, cell-to-cell carbon transfer, and cell-specific nitrate-based growth using microscopy (e.g., fluorescence in situ hybridization), 16S rRNA gene amplicon sequencing, and secondary ion mass spectrometry. Bacterial abundances were 2 to 4 times higher on individual fungal-infected diatoms compared to healthy diatoms, particularly involving Burkholderiales. Furthermore, taxonomic compositions of both diatom-associated and free-living bacteria were significantly different between noninfected and fungal-infected cocultures. The fungal microparasite, including diatom-associated sporangia and free-swimming zoospores, derived ∼100% of their carbon content from the diatom. By comparison, transfer efficiencies of photosynthetic carbon were lower to diatom-associated bacteria (67 to 98%), with a high cell-to-cell variability, and even lower to free-living bacteria (32%). Likewise, nitrate-based growth for the diatom and fungi was synchronized and faster than for diatom-associated and free-living bacteria. In a natural lacustrine system, where infection prevalence reached 54%, we calculated that 20% of the total diatom-derived photosynthetic carbon was shunted to the parasitic fungi, which can be grazed by zooplankton, thereby accelerating carbon transfer to higher trophic levels and bypassing the microbial loop. The herein termed “fungal shunt” can thus significantly modify the fate of photosynthetic carbon and the nature of phytoplankton–bacteria interactions, with implications for diverse pelagic food webs and global biogeochemical cycles.
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17
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Lin Y, Wang L, Xu K, Huang H, Ren H. Algae Biofilm Reduces Microbe-Derived Dissolved Organic Nitrogen Discharges: Performance and Mechanisms. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:6227-6238. [PMID: 33891391 DOI: 10.1021/acs.est.0c06915] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Microbe-derived dissolved organic nitrogen (mDON) can readily induce harmful phytoplankton blooms, and thus, restricting its discharges is necessary. Recently, algae biofilm (AB) has attracted increasing interest for its advantages in nutrient recovery. However, its features in mDON control remain unexplored. Herein, AB's mDON formation and utilization performance, molecular characteristics, and metabolic traits have been investigated, with activated sludge (AS) as the benchmark for comparisons. Comparatively, AB reduced mDON formation by 83% when fed with DON-free wastewater. When fed with AS's effluent, it consumed at least 72% of the exogenous mDON and notably reduced the amount of protein/amino sugar-like compounds. Irrespective of the influent, AB ultimately produced more various unsaturated hydrocarbon and lignin analogues. Redundancy and network analysis highlighted the algal-bacterial synergistic effects exemplified by cross-feeding in reducing mDON concentrations and shaping mDON pools. Moreover, metagenomics-based metabolic reconstruction revealed that cyanobacteria Limnothrix and Kamptonema spp. facilitated mDON uptake, ammonification, and recycling, which supplied the extensive nitrogen assimilatory demand for amino acids, vitamins, and cofactors biosynthesis, and therefore promoted mDON scavenging. Our findings demonstrate that regardless of the secondary or tertiary process, cyanobacteria-dominated AB is promising to minimize bioavailable mDON discharges, which has implications for future eutrophication control.
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Affiliation(s)
- Yuan Lin
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, No. 163 Xianlin Avenue, Nanjing 210023, Jiangsu, P. R. China
| | - Liye Wang
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, No. 163 Xianlin Avenue, Nanjing 210023, Jiangsu, P. R. China
| | - Ke Xu
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, No. 163 Xianlin Avenue, Nanjing 210023, Jiangsu, P. R. China
| | - Hui Huang
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, No. 163 Xianlin Avenue, Nanjing 210023, Jiangsu, P. R. China
| | - Hongqiang Ren
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, No. 163 Xianlin Avenue, Nanjing 210023, Jiangsu, P. R. China
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18
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Broman E, Zilius M, Samuiloviene A, Vybernaite-Lubiene I, Politi T, Klawonn I, Voss M, Nascimento FJA, Bonaglia S. Active DNRA and denitrification in oxic hypereutrophic waters. WATER RESEARCH 2021; 194:116954. [PMID: 33667950 DOI: 10.1016/j.watres.2021.116954] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Revised: 02/17/2021] [Accepted: 02/18/2021] [Indexed: 06/12/2023]
Abstract
Since the start of synthetic fertilizer production more than a hundred years ago, the coastal ocean has been exposed to increasing nutrient loading, which has led to eutrophication and extensive algal blooms. Such hypereutrophic waters might harbor anaerobic nitrogen (N) cycling processes due to low-oxygen microniches associated with abundant organic particles, but studies on nitrate reduction in coastal pelagic environments are scarce. Here, we report on 15N isotope-labeling experiments, metagenome, and RT-qPCR data from a large hypereutrophic lagoon indicating that dissimilatory nitrate reduction to ammonium (DNRA) and denitrification were active processes, even though the bulk water was fully oxygenated (> 224 µM O2). DNRA in the bottom water corresponded to 83% of whole-ecosystem DNRA (water + sediment), while denitrification was predominant in the sediment. Microbial taxa important for DNRA according to the metagenomic data were dominated by Bacteroidetes (genus Parabacteroides) and Proteobacteria (genus Wolinella), while denitrification was mainly associated with proteobacterial genera Pseudomonas, Achromobacter, and Brucella. The metagenomic and microscopy data suggest that these anaerobic processes were likely occurring in low-oxygen microniches related to extensive growth of filamentous cyanobacteria, including diazotrophic Dolichospermum and non-diazotrophic Planktothrix. By summing the total nitrate fluxes through DNRA and denitrification, it results that DNRA retains approximately one fifth (19%) of the fixed N that goes through the nitrate pool. This is noteworthy as DNRA represents thus a very important recycling mechanism for fixed N, which sustains algal proliferation and leads to further enhancement of eutrophication in these endangered ecosystems.
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Affiliation(s)
- Elias Broman
- Department of Ecology, Environment and Plant Sciences, Stockholm University, 106 91 Stockholm, Sweden; Baltic Sea Centre, Stockholm University, 106 91 Stockholm, Sweden.
| | - Mindaugas Zilius
- Marine Research Institute, Klaipeda University, 92294 Klaipeda, Lithuania
| | | | | | - Tobia Politi
- Marine Research Institute, Klaipeda University, 92294 Klaipeda, Lithuania
| | - Isabell Klawonn
- Department of Biological Oceanography, Leibniz Institute for Baltic Sea Research Warnemünde, Seestr. 15, 18119 Rostock, Germany
| | - Maren Voss
- Department of Biological Oceanography, Leibniz Institute for Baltic Sea Research Warnemünde, Seestr. 15, 18119 Rostock, Germany
| | - Francisco J A Nascimento
- Department of Ecology, Environment and Plant Sciences, Stockholm University, 106 91 Stockholm, Sweden; Baltic Sea Centre, Stockholm University, 106 91 Stockholm, Sweden
| | - Stefano Bonaglia
- Department of Ecology, Environment and Plant Sciences, Stockholm University, 106 91 Stockholm, Sweden; Marine Research Institute, Klaipeda University, 92294 Klaipeda, Lithuania; Department of Biology, University of Southern Denmark, 5230 Odense, Denmark; Department of Marine Sciences, University of Gothenburg, Box 461, 405 30 Gothenburg, Sweden.
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19
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Ammonia-oxidizing archaea in biological interactions. J Microbiol 2021; 59:298-310. [DOI: 10.1007/s12275-021-1005-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 01/28/2021] [Accepted: 01/29/2021] [Indexed: 10/22/2022]
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20
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Olofsson M, Klawonn I, Karlson B. Nitrogen fixation estimates for the Baltic Sea indicate high rates for the previously overlooked Bothnian Sea. AMBIO 2021; 50:203-214. [PMID: 32314265 PMCID: PMC7708615 DOI: 10.1007/s13280-020-01331-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Revised: 11/22/2019] [Accepted: 03/20/2020] [Indexed: 05/05/2023]
Abstract
Dense blooms of diazotrophic filamentous cyanobacteria are formed every summer in the Baltic Sea. We estimated their contribution to nitrogen fixation by combining two decades of cyanobacterial biovolume monitoring data with recently measured genera-specific nitrogen fixation rates. In the Bothnian Sea, estimated nitrogen fixation rates were 80 kt N year-1, which has doubled during recent decades and now exceeds external loading from rivers and atmospheric deposition of 69 kt year-1. The estimated contribution to the Baltic Proper was 399 kt N year-1, which agrees well with previous estimates using other approaches and is greater than the external input of 374 kt N year-1. Our approach can potentially be applied to continuously estimate nitrogen loads via nitrogen fixation. Those estimates are crucial for ecosystem adaptive management since internal nitrogen loading may counteract the positive effects of decreased external nutrient loading.
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Affiliation(s)
- Malin Olofsson
- Research and Development, Oceanography, Swedish Meteorological and Hydrological Institute, Sven Källfelts Gata 15, 426 71 Västra Frölunda, Gothenburg, Sweden
- Present Address: Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Isabell Klawonn
- Department of Experimental Limnology, IGB-Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Alte Fischerhütte 2, OT Neuglobsow, Stechlin, 16775 Berlin, Germany
| | - Bengt Karlson
- Research and Development, Oceanography, Swedish Meteorological and Hydrological Institute, Sven Källfelts Gata 15, 426 71 Västra Frölunda, Gothenburg, Sweden
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21
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Bird C, LeKieffre C, Jauffrais T, Meibom A, Geslin E, Filipsson HL, Maire O, Russell AD, Fehrenbacher JS. Heterotrophic Foraminifera Capable of Inorganic Nitrogen Assimilation. Front Microbiol 2020; 11:604979. [PMID: 33343548 PMCID: PMC7744380 DOI: 10.3389/fmicb.2020.604979] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 11/11/2020] [Indexed: 11/17/2022] Open
Abstract
Nitrogen availability often limits biological productivity in marine systems, where inorganic nitrogen, such as ammonium is assimilated into the food web by bacteria and photoautotrophic eukaryotes. Recently, ammonium assimilation was observed in kleptoplast-containing protists of the phylum foraminifera, possibly via the glutamine synthetase/glutamate synthase (GS/GOGAT) assimilation pathway imported with the kleptoplasts. However, it is not known if the ubiquitous and diverse heterotrophic protists have an innate ability for ammonium assimilation. Using stable isotope incubations (15N-ammonium and 13C-bicarbonate) and combining transmission electron microscopy (TEM) with quantitative nanoscale secondary ion mass spectrometry (NanoSIMS) imaging, we investigated the uptake and assimilation of dissolved inorganic ammonium by two heterotrophic foraminifera; a non-kleptoplastic benthic species, Ammonia sp., and a planktonic species, Globigerina bulloides. These species are heterotrophic and not capable of photosynthesis. Accordingly, they did not assimilate 13C-bicarbonate. However, both species assimilated dissolved 15N-ammonium and incorporated it into organelles of direct importance for ontogenetic growth and development of the cell. These observations demonstrate that at least some heterotrophic protists have an innate cellular mechanism for inorganic ammonium assimilation, highlighting a newly discovered pathway for dissolved inorganic nitrogen (DIN) assimilation within the marine microbial loop.
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Affiliation(s)
- Clare Bird
- Biological and Environmental Sciences, Faculty of Natural Sciences, University of Stirling, Stirling, United Kingdom.,School of GeoSciences, Grant Institute, University of Edinburgh, Edinburgh, United Kingdom
| | - Charlotte LeKieffre
- Laboratory for Biological Geochemistry, School of Architecture, Civil and Environmental Engineering (ENAC), Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.,UMR CNRS 6112 LPG, Bio-Indicateurs Actuels et Fossiles, Université d'Angers, Angers, France
| | - Thierry Jauffrais
- Ifremer, IRD, Univ Nouvelle-Calédonie, Univ La Réunion, CNRS, UMR 9220 ENTROPIE, Nouméa, New Caledonia
| | - Anders Meibom
- Laboratory for Biological Geochemistry, School of Architecture, Civil and Environmental Engineering (ENAC), Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.,Centre for Advanced Surface Analysis, Institute of Earth Sciences, University of Lausanne, Lausanne, Switzerland
| | - Emmanuelle Geslin
- UMR CNRS 6112 LPG, Bio-Indicateurs Actuels et Fossiles, Université d'Angers, Angers, France
| | | | - Olivier Maire
- Université de Bordeaux, EPOC, UMR 5805, Talence, France.,CNRS, EPOC, UMR 5805, Talence, France
| | - Ann D Russell
- Department of Earth and Planetary Sciences, University of California, Davis, Davis, CA, United States
| | - Jennifer S Fehrenbacher
- College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR, United States
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22
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Zhang W, Dong Z, Zhang C, Sun X, Hou C, Liu Y, Wang L, Ma Y, Zhao J. Effects of physical-biochemical coupling processes on the Noctiluca scintillans and Mesodinium red tides in October 2019 in the Yantai nearshore, China. MARINE POLLUTION BULLETIN 2020; 160:111609. [PMID: 32890961 DOI: 10.1016/j.marpolbul.2020.111609] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 08/24/2020] [Accepted: 08/24/2020] [Indexed: 06/11/2023]
Abstract
Red tide has always been an environmental issue with global concern. A Noctiluca scintillans red tide and a Mesodinium red tide occurred successively in Yantai nearshore, China, where is usually oligotrophic, in October 2019. Currents, phytoplankton community composition and nutrients were analyzed to access the driving factors of the red tides. The maximum N. scintillans and Mesodiniium abundance reached 124.92 ± 236.84 × 103 cells/L and 1157.52 ± 1294.16 × 103 cells/L respectively. The fast growth of N. scintillans was due to increasing abundance of phytoplankton. The currents were crucial to the assembly and dispersal of red tides. The red tides significantly redistributed the nutrients in the red tide patches and regulated the dominant species in phytoplankton community. Our study illuminates the influence of physical-biochemical coupling processes on red tides, and suggests that ocean dynamics such as currents and tidal factors deserve more attention when considering the ecosystem health problems of coastal zones.
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Affiliation(s)
- Wenjing Zhang
- Muping Coastal Environmental Research Station, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, P.R. China; University of Chinese Academy of Sciences, Beijing 100049, P.R. China; Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, P.R. China; Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, Shandong 264003, P.R. China
| | - Zhijun Dong
- Muping Coastal Environmental Research Station, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, P.R. China; Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, P.R. China
| | - Chen Zhang
- Muping Coastal Environmental Research Station, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, P.R. China; Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, P.R. China.
| | - Xiyan Sun
- Muping Coastal Environmental Research Station, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, P.R. China; Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, P.R. China
| | - Chaowei Hou
- Muping Coastal Environmental Research Station, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, P.R. China; Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, P.R. China
| | - Yongliang Liu
- Muping Coastal Environmental Research Station, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, P.R. China; Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, P.R. China
| | - Lei Wang
- Muping Coastal Environmental Research Station, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, P.R. China; Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, P.R. China
| | - Yuanqing Ma
- Shandong Key Laboratory of Marine Ecological Restoration, Shandong Marine Resources and Environment Research Institute, Yantai 264006, Shandong, P.R. China
| | - Jianmin Zhao
- Muping Coastal Environmental Research Station, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, P.R. China; Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, P.R. China
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Zecher K, Hayes KR, Philipp B. Evidence of Interdomain Ammonium Cross-Feeding From Methylamine- and Glycine Betaine-Degrading Rhodobacteraceae to Diatoms as a Widespread Interaction in the Marine Phycosphere. Front Microbiol 2020; 11:533894. [PMID: 33123096 PMCID: PMC7574528 DOI: 10.3389/fmicb.2020.533894] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Accepted: 09/10/2020] [Indexed: 11/13/2022] Open
Abstract
Dissolved organic nitrogen (DON) compounds such as methylamines (MAs) and glycine betaine (GBT) occur at detectable concentrations in marine habitats and are also produced and released by microalgae. For many marine bacteria, these DON compounds can serve as carbon, energy, and nitrogen sources, but microalgae usually cannot metabolize them. Interestingly though, it was previously shown that Donghicola sp. strain KarMa—a member of the marine Rhodobacteraceae—can cross-feed ammonium such that the ammonium it produces upon degrading monomethylamine (MMA) then serves as nitrogen source for the diatom Phaeodactylum tricornutum; thus, these organisms form a mutual metabolic interaction under photoautotrophic conditions. In the present study, we investigated whether this interaction plays a broader role in bacteria–diatom interactions in general. Results showed that cross-feeding between strain KarMa and P. tricornutum was also possible with di- and trimethylamine as well as with GBT. Further, cross-feeding of strain KarMa was also observed in cocultures with the diatoms Amphora coffeaeformis and Thalassiosira pseudonana with MMA as the sole nitrogen source. Regarding cross-feeding involving other Rhodobacteraceae strains, the in silico analysis of MA and GBT degradation pathways indicated that algae-associated Rhodobacteraceae-type strains likely interact with P. tricornutum in a similar manner as the strain KarMa does. For these types of strains (such as Celeribacter halophilus, Roseobacter denitrificans, Roseovarius indicus, Ruegeria pomeroyi, and Sulfitobacter noctilucicola), ammonium cross-feeding after methylamine degradation showed species-specific patterns, whereas bacterial GBT degradation always led to diatom growth. Overall, the degradation of DON compounds by the Rhodobacteraceae family and the subsequent cross-feeding of ammonium may represent a widespread, organism-specific, and regulated metabolic interaction for establishing and stabilizing associations with photoautotrophic diatoms in the oceans.
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Affiliation(s)
- Karsten Zecher
- Institute for Molecular Microbiology and Biotechnology, University of Münster, Münster, Germany
| | - Kristiane Rebecca Hayes
- Institute for Molecular Microbiology and Biotechnology, University of Münster, Münster, Germany
| | - Bodo Philipp
- Institute for Molecular Microbiology and Biotechnology, University of Münster, Münster, Germany
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LeKieffre C, Spero HJ, Fehrenbacher JS, Russell AD, Ren H, Geslin E, Meibom A. Ammonium is the preferred source of nitrogen for planktonic foraminifer and their dinoflagellate symbionts. Proc Biol Sci 2020; 287:20200620. [PMID: 32546098 PMCID: PMC7329048 DOI: 10.1098/rspb.2020.0620] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The symbiotic planktonic foraminifera Orbulina universa inhabits open ocean oligotrophic ecosystems where dissolved nutrients are scarce and often limit biological productivity. It has previously been proposed that O. universa meets its nitrogen (N) requirements by preying on zooplankton, and that its symbiotic dinoflagellates recycle metabolic ‘waste ammonium’ for their N pool. However, these conclusions were derived from bulk 15N-enrichment experiments and model calculations, and our understanding of N assimilation and exchange between the foraminifer host cell and its symbiotic dinoflagellates remains poorly constrained. Here, we present data from pulse-chase experiments with 13C-enriched inorganic carbon, 15N-nitrate, and 15N-ammonium, as well as a 13C- and 15N- enriched heterotrophic food source, followed by TEM (transmission electron microscopy) coupled to NanoSIMS (nanoscale secondary ion mass spectrometry) isotopic imaging to visualize and quantify C and N assimilation and translocation in the symbiotic system. High levels of 15N-labelling were observed in the dinoflagellates and in foraminiferal organelles and cytoplasm after incubation with 15N-ammonium, indicating efficient ammonium assimilation. Only weak 15N-assimilation was observed after incubation with 15N-nitrate. Feeding foraminifers with 13C- and 15N-labelled food resulted in dinoflagellates that were labelled with 15N, thereby confirming the transfer of 15N-compounds from the digestive vacuoles of the foraminifer to the symbiotic dinoflagellates, likely through recycling of ammonium. These observations are important for N isotope-based palaeoceanographic reconstructions, as they show that δ15N values recorded in the organic matrix in symbiotic species likely reflect ammonium recycling rather than alternative N sources, such as nitrates.
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Affiliation(s)
- Charlotte LeKieffre
- Laboratory for Biological Geochemistry, School of Architecture, Civil and Environmental Engineering (ENAC), Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland.,UMR CNRS 6112 - LPG-BIAF, Université d'Angers, 49045 Angers Cedex, France
| | - Howard J Spero
- Department of Earth and Planetary Sciences, University of California Davis, Davis, CA 95616, USA
| | - Jennifer S Fehrenbacher
- College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR 97331, USA
| | - Ann D Russell
- Department of Earth and Planetary Sciences, University of California Davis, Davis, CA 95616, USA
| | - Haojia Ren
- Department of Geosciences, National Taiwan University, Taipei, Taiwan
| | - Emmanuelle Geslin
- UMR CNRS 6112 - LPG-BIAF, Université d'Angers, 49045 Angers Cedex, France
| | - Anders Meibom
- Laboratory for Biological Geochemistry, School of Architecture, Civil and Environmental Engineering (ENAC), Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland.,Center for Advanced Surface Analysis, Institute of Earth Sciences, University of Lausanne, Switzerland
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25
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Derilus D, Rahman MZ, Pinero F, Massey SE. Synergism between the Black Queen effect and the proteomic constraint on genome size reduction in the photosynthetic picoeukaryotes. Sci Rep 2020; 10:8918. [PMID: 32488045 PMCID: PMC7265537 DOI: 10.1038/s41598-020-65476-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Accepted: 05/05/2020] [Indexed: 01/01/2023] Open
Abstract
The photosynthetic picoeukaryotes (PPEs) comprise a rare example of free-living eukaryotes that have undergone genome reduction. Here, we examine a duality in the process; the proposed driver of genome reduction (the Black Queen hypothesis, BQH), and the resultant impact of genome information loss (the Proteomic Constraint hypothesis, PCH). The BQH predicts that some metabolites may be shared in the open ocean, thus driving loss of redundant metabolic pathways in individual genomes. In contrast, the PCH predicts that as the information content of a genome is reduced, the total mutation load is also reduced, leading to loss of DNA repair genes due to the resulting reduction in selective constraint. Consistent with the BQH, we observe that biosynthetic pathways involved with soluble metabolites such as amino acids and carotenoids are preferentially lost from the PPEs, in contrast to biosynthetic pathways involved with insoluble metabolites, such as lipids, which are retained. Consistent with the PCH, a correlation between proteome size and the number of DNA repair genes, and numerous other informational categories, is observed. While elevated mutation rates resulting from the loss of DNA repair genes have been linked to reduced effective population sizes in intracellular bacteria, this remains to be established. This study shows that in microbial species with large population sizes, an underlying factor in modulating their DNA repair capacity appears to be information content.
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Affiliation(s)
- D Derilus
- Environmental Sciences Department, University of Puerto Rico - Rio Piedras, San Juan, Puerto Rico
| | - M Z Rahman
- Biology Department, University of Puerto Rico - Rio Piedras, San Juan, Puerto Rico
| | - F Pinero
- Mathematics Department, University of Puerto Rico - Ponce, Ponce, Puerto Rico
| | - S E Massey
- Biology Department, University of Puerto Rico - Rio Piedras, San Juan, Puerto Rico.
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26
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Carstensen J, Conley DJ, Almroth-Rosell E, Asmala E, Bonsdorff E, Fleming-Lehtinen V, Gustafsson BG, Gustafsson C, Heiskanen AS, Janas U, Norkko A, Slomp C, Villnäs A, Voss M, Zilius M. Factors regulating the coastal nutrient filter in the Baltic Sea. AMBIO 2020; 49:1194-1210. [PMID: 31707582 PMCID: PMC7128010 DOI: 10.1007/s13280-019-01282-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 09/17/2019] [Accepted: 09/23/2019] [Indexed: 05/30/2023]
Abstract
The coastal zone of the Baltic Sea is diverse with strong regional differences in the physico-chemical setting. This diversity is also reflected in the importance of different biogeochemical processes altering nutrient and organic matter fluxes on the passage from land to sea. This review investigates the most important processes for removal of nutrients and organic matter, and the factors that regulate the efficiency of the coastal filter. Nitrogen removal through denitrification is high in lagoons receiving large inputs of nitrate and organic matter. Phosphorus burial is high in archipelagos with substantial sedimentation, but the stability of different burial forms varies across the Baltic Sea. Organic matter processes are tightly linked to the nitrogen and phosphorus cycles. Moreover, these processes are strongly modulated depending on composition of vegetation and fauna. Managing coastal ecosystems to improve the effectiveness of the coastal filter can reduce eutrophication in the open Baltic Sea.
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Affiliation(s)
- Jacob Carstensen
- Department of Bioscience, Aarhus University, Frederiksborgvej 399, 4000 Roskilde, Denmark
| | - Daniel J. Conley
- Department of Geology, Lund University, Sölvegatan 12, 223 62 Lund, Sweden
| | | | - Eero Asmala
- Tvärminne Zoological Station, University of Helsinki, J.A. Palmenin tie 260, 10900 Hanko, Finland
| | - Erik Bonsdorff
- Environmental and Marine Biology, Åbo Akademi University, BioCity, 20500 Turku, Finland
| | | | - Bo G. Gustafsson
- Tvärminne Zoological Station, University of Helsinki, J.A. Palmenin tie 260, 10900 Hanko, Finland
- Stockholm University Baltic Sea Centre, 106 91 Stockholm, Sweden
| | - Camilla Gustafsson
- Tvärminne Zoological Station, University of Helsinki, J.A. Palmenin tie 260, 10900 Hanko, Finland
| | | | - Urzsula Janas
- Department of Experimental Ecology of Marine Organisms, Institute of Oceanography, University of Gdańsk, al. Marsz. J. Pilsudskiego 46, 81-378 Gdynia, Poland
| | - Alf Norkko
- Tvärminne Zoological Station, University of Helsinki, J.A. Palmenin tie 260, 10900 Hanko, Finland
| | - Caroline Slomp
- Department of Earth Sciences, Utrecht University, Princetonlaan 8A, 3584 CB Utrecht, The Netherlands
| | - Anna Villnäs
- Tvärminne Zoological Station, University of Helsinki, J.A. Palmenin tie 260, 10900 Hanko, Finland
| | - Maren Voss
- Department of Biological Oceanography, Leibniz Institute of Baltic Sea Research, Seestr. 15, 18119 Rostock, Germany
| | - Mindaugas Zilius
- Marine Research Institute, Universiteto al. 17, 92294 Klaipeda, Lithuania
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27
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Stenow R, Olofsson M, Robertson EK, Kourtchenko O, Whitehouse MJ, Ploug H, Godhe A. Resting Stages of Skeletonema marinoi Assimilate Nitrogen From the Ambient Environment Under Dark, Anoxic Conditions. JOURNAL OF PHYCOLOGY 2020; 56:699-708. [PMID: 32012281 DOI: 10.1111/jpy.12975] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Accepted: 01/02/2020] [Indexed: 06/10/2023]
Abstract
The planktonic marine diatom Skeletonema marinoi forms resting stages, which can survive for decades buried in aphotic, anoxic sediments and resume growth when re-exposed to light, oxygen, and nutrients. The mechanisms by which they maintain cell viability during dormancy are poorly known. Here, we investigated cell-specific nitrogen (N) and carbon (C) assimilation and survival rate in resting stages of three S. marinoi strains. Resting stages were incubated with stable isotopes of dissolved inorganic N (DIN), in the form of 15 N-ammonium (NH4+ ) or -nitrate (NO3- ) and dissolved inorganic C (DIC) as 13 C-bicarbonate (HCO3- ) under dark and anoxic conditions for 2 months. Particulate C and N concentration remained close to the Redfield ratio (6.6) during the experiment, indicating viable diatoms. However, survival varied between <0.1% and 47.6% among the three different S. marinoi strains, and overall survival was higher when NO3- was available. One strain did not survive in the NH4+ treatment. Using secondary ion mass spectrometry (SIMS), we quantified assimilation of labeled DIC and DIN from the ambient environment within the resting stages. Dark fixation of DIC was insignificant across all strains. Significant assimilation of 15 N-NO3- and 15 N-NH4+ occurred in all S. marinoi strains at rates that would double the nitrogenous biomass over 77-380 years depending on strain and treatment. Hence, resting stages of S. marinoi assimilate N from the ambient environment at slow rates during darkness and anoxia. This activity may explain their well-documented long survival and swift resumption of vegetative growth after dormancy in dark and anoxic sediments.
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Affiliation(s)
- Rickard Stenow
- Department of Marine Sciences, University of Gothenburg, Box 461, SE 405 30, Gothenburg, Sweden
| | - Malin Olofsson
- Department of Marine Sciences, University of Gothenburg, Box 461, SE 405 30, Gothenburg, Sweden
| | - Elizabeth K Robertson
- Department of Marine Sciences, University of Gothenburg, Box 461, SE 405 30, Gothenburg, Sweden
| | - Olga Kourtchenko
- Department of Marine Sciences, University of Gothenburg, Box 461, SE 405 30, Gothenburg, Sweden
| | | | - Helle Ploug
- Department of Marine Sciences, University of Gothenburg, Box 461, SE 405 30, Gothenburg, Sweden
| | - Anna Godhe
- Department of Marine Sciences, University of Gothenburg, Box 461, SE 405 30, Gothenburg, Sweden
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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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