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Zou C, Yi X, Li H, Bizic M, Berman-Frank I, Gao K. Correlation of methane production with physiological traits in Trichodesmium IMS 101 grown with methylphosphonate at different temperatures. Front Microbiol 2024; 15:1396369. [PMID: 38894967 PMCID: PMC11184136 DOI: 10.3389/fmicb.2024.1396369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Accepted: 05/20/2024] [Indexed: 06/21/2024] Open
Abstract
The diazotrophic cyanobacterium Trichodesmium has been recognized as a potentially significant contributor to aerobic methane generation via several mechanisms including the utilization of methylphophonate (MPn) as a source of phosphorus. Currently, there is no information about how environmental factors regulate methane production by Trichodesmium. Here, we grew Trichodesmium IMS101 at five temperatures ranging from 16 to 31°C, and found that its methane production rates increased with rising temperatures to peak (1.028 ± 0.040 nmol CH4 μmol POC-1 day-1) at 27°C, and then declined. Its specific growth rate changed from 0.03 ± 0.01 d-1 to 0.34 ± 0.02 d-1, with the optimal growth temperature identified between 27 and 31°C. Within the tested temperature range the Q10 for the methane production rate was 4.6 ± 0.7, indicating a high sensitivity to thermal changes. In parallel, the methane production rates showed robust positive correlations with the assimilation rates of carbon, nitrogen, and phosphorus, resulting in the methane production quotients (molar ratio of carbon, nitrogen, or phosphorus assimilated to methane produced) of 227-494 for carbon, 40-128 for nitrogen, and 1.8-3.4 for phosphorus within the tested temperature range. Based on the experimental data, we estimated that the methane released from Trichodesmium can offset about 1% of its CO2 mitigation effects.
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Affiliation(s)
- Chuze Zou
- State Key Laboratory of Marine Environmental Science, College of the Ocean and Earth Sciences, Xiamen University, Xiamen, China
| | - Xiangqi Yi
- Polar and Marine Research Institute, College of Harbor and Coastal Engineering, Jimei University, Xiamen, China
| | - He Li
- Co-Innovation Center of Jiangsu Marine Bio-industry Technology, Jiangsu Ocean University, Lianyungang, China
| | - Mina Bizic
- Department of Environmental Microbiomics, Institute of Environmental Technology, Technical University of Berlin, Berlin, Germany
- Department of Plankton and Microbial Ecology, Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Stechlin, Germany
| | - Ilana Berman-Frank
- Department of Marine Biology, Leon H. Charney School of Marine Sciences, University of Haifa, Haifa, Israel
| | - Kunshan Gao
- State Key Laboratory of Marine Environmental Science, College of the Ocean and Earth Sciences, Xiamen University, Xiamen, China
- Co-Innovation Center of Jiangsu Marine Bio-industry Technology, Jiangsu Ocean University, Lianyungang, China
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2
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Zhang B, Chellman NJ, Kaplan JO, Mickley LJ, Ito T, Wang X, Wensman SM, McCrimmon D, Steffensen JP, McConnell JR, Liu P. Improved biomass burning emissions from 1750 to 2010 using ice core records and inverse modeling. Nat Commun 2024; 15:3651. [PMID: 38688918 PMCID: PMC11061293 DOI: 10.1038/s41467-024-47864-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Accepted: 04/08/2024] [Indexed: 05/02/2024] Open
Abstract
Estimating fire emissions prior to the satellite era is challenging because observations are limited, leading to large uncertainties in the calculated aerosol climate forcing following the preindustrial era. This challenge further limits the ability of climate models to accurately project future climate change. Here, we reconstruct a gridded dataset of global biomass burning emissions from 1750 to 2010 using inverse analysis that leveraged a global array of 31 ice core records of black carbon deposition fluxes, two different historical emission inventories as a priori estimates, and emission-deposition sensitivities simulated by the atmospheric chemical transport model GEOS-Chem. The reconstructed emissions exhibit greater temporal variabilities which are more consistent with paleoclimate proxies. Our ice core constrained emissions reduced the uncertainties in simulated cloud condensation nuclei and aerosol radiative forcing associated with the discrepancy in preindustrial biomass burning emissions. The derived emissions can also be used in studies of ocean and terrestrial biogeochemistry.
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Affiliation(s)
- Bingqing Zhang
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, USA
| | - Nathan J Chellman
- Division of Hydrologic Sciences, Desert Research Institute, Reno, NV, USA
| | - Jed O Kaplan
- Department of Earth, Energy, and Environment, University of Calgary, Calgary, AB, Canada
| | - Loretta J Mickley
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Takamitsu Ito
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, USA
| | - Xuan Wang
- School of Energy and Environment, City University of Hong Kong, Hong Kong SAR, China
| | - Sophia M Wensman
- Division of Hydrologic Sciences, Desert Research Institute, Reno, NV, USA
| | - Drake McCrimmon
- Division of Hydrologic Sciences, Desert Research Institute, Reno, NV, USA
| | - Jørgen Peder Steffensen
- Physics of Ice, Climate, and Earth, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
| | - Joseph R McConnell
- Division of Hydrologic Sciences, Desert Research Institute, Reno, NV, USA
| | - Pengfei Liu
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, USA.
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3
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Martin B, Koppelmann R, Harmer A, Plonus RM. Possible transport pathway of diazotrophic Trichodesmium by Agulhas Leakage from the Indian into the Atlantic Ocean. Sci Rep 2024; 14:2906. [PMID: 38316872 PMCID: PMC10844604 DOI: 10.1038/s41598-024-53297-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Accepted: 01/30/2024] [Indexed: 02/07/2024] Open
Abstract
Diazotrophic cyanobacteria such as Trichodesmium play a crucial role in the nitrogen budget of the oceans due to their capability to bind atmospheric nitrogen. Little is known about their interoceanic transport pathways and their distribution in upwelling regions. Trichodesmium has been detected using a Video Plankton Recorder (VPR) mounted on a remotely operated towed vehicle (TRIAXUS) in the southern and northern Benguela Upwelling System (BUS) in austral autumn, Feb/Mar 2019. The TRIAXUS, equipped with a CTD as well as fluorescence and nitrogen sensors, was towed at a speed of 8 kn on two onshore-offshore transects undulating between 5 and 200 m over distances of 249 km and 372 km, respectively. Trichodesmium was not detected near the coast in areas of freshly upwelled waters but was found in higher abundances offshore on both transects, mainly in subsurface water layers down to 80 m depth with elevated salinities. These salinity lenses can be related to northward moving eddies that most probably have been detached from the warm and salty Agulhas Current. Testing for interaction and species-habitat associations of Trichodesmium colonies with salinity yielded significant results, indicating that Trichodesmium may be transported with Agulhas Rings from the Indian Ocean into the Atlantic Ocean.
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Affiliation(s)
- Bettina Martin
- Institute of Marine Ecosystem and Fishery Science, Universität Hamburg, Hamburg, Germany.
| | - Rolf Koppelmann
- Institute of Marine Ecosystem and Fishery Science, Universität Hamburg, Hamburg, Germany
| | - André Harmer
- Institute of Marine Ecosystem and Fishery Science, Universität Hamburg, Hamburg, Germany
| | - Rene-Marcel Plonus
- Institute of Marine Ecosystem and Fishery Science, Universität Hamburg, Hamburg, Germany
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4
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Mao Y, Lin T, Li H, He R, Ye K, Yu W, He Q. Aerobic methane production by phytoplankton as an important methane source of aquatic ecosystems: Reconsidering the global methane budget. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 907:167864. [PMID: 37866611 DOI: 10.1016/j.scitotenv.2023.167864] [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: 08/10/2023] [Revised: 10/09/2023] [Accepted: 10/13/2023] [Indexed: 10/24/2023]
Abstract
Biological methane, a major source of global methane budget, is traditionally thought to be produced in anaerobic environments. However, the recent reports about methane supersaturation occurring in oxygenated water layer, termed as "methane paradox", have challenged this prevailing paradigm. Significantly, growing evidence has indicated that phytoplankton including prokaryotic cyanobacteria and eukaryotic algae are capable of generating methane under aerobic conditions. In this regard, a systematic review of aerobic methane production by phytoplankton is expected to arouse the public attention, contributing to the understanding of methane paradox. Here, we comprehensively summarize the widespread phenomena of methane supersaturation in oxic layers. The remarkable correlation relationships between methane concentration and several key indicators (depth, chlorophyll a level and organic sulfide concentration) indicate the significance of phytoplankton in in-situ methane accumulation. Subsequently, four mechanisms of aerobic methane production by phytoplankton are illustrated in detail, including photosynthesis-driven metabolism, reactive oxygen species (ROS)-driven demethylation of methyl donors, methanogenesis catalyzed by nitrogenase and demethylation of phosphonates catalyzed by CP lyase. The first two pathways occur in various phytoplankton, while the latter two have been specially discovered in cyanobacteria. Additionally, the effects of four crucial factors on aerobic methane production by phytoplankton are also discussed, including phytoplankton species, light, temperature and crucial nutrients. Finally, the measures to control global methane emissions from phytoplankton, the precise intracellular mechanisms of methane production and a more complete global methane budget model are definitely required in the future research on methane production by phytoplankton. This review would provide guidance for future studies of aerobic methane production by phytoplankton and emphasize the potential contribution of aquatic ecosystems to global methane budget.
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Affiliation(s)
- Yufeng Mao
- Key Laboratory of Eco-Environment of Three Gorges Region, Ministry of Education, Chongqing University, Chongqing 400044, China; Key Laboratory of Hydraulic and Waterway Engineering, Ministry of Education, Chongqing Jiaotong University, Chongqing 400074, China; Lingzhi Environmental Protection Co., Ltd, Wuxi 214200, China
| | - Tong Lin
- Key Laboratory of Eco-Environment of Three Gorges Region, Ministry of Education, Chongqing University, Chongqing 400044, China
| | - Hong Li
- Key Laboratory of Eco-Environment of Three Gorges Region, Ministry of Education, Chongqing University, Chongqing 400044, China
| | - Ruixu He
- Key Laboratory of Hydraulic and Waterway Engineering, Ministry of Education, Chongqing Jiaotong University, Chongqing 400074, China
| | - Kailai Ye
- Key Laboratory of Hydraulic and Waterway Engineering, Ministry of Education, Chongqing Jiaotong University, Chongqing 400074, China
| | - Weiwei Yu
- Key Laboratory of Hydraulic and Waterway Engineering, Ministry of Education, Chongqing Jiaotong University, Chongqing 400074, China
| | - Qiang He
- Key Laboratory of Eco-Environment of Three Gorges Region, Ministry of Education, Chongqing University, Chongqing 400044, China.
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Jiang HB, Hutchins DA, Ma W, Zhang RF, Wells M, Jiao N, Wang Y, Chai F. Natural ocean iron fertilization and climate variability over geological periods. GLOBAL CHANGE BIOLOGY 2023; 29:6856-6866. [PMID: 37855153 DOI: 10.1111/gcb.16990] [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: 07/18/2023] [Revised: 09/20/2023] [Accepted: 09/27/2023] [Indexed: 10/20/2023]
Abstract
Marine primary producers are largely dependent on and shape the Earth's climate, although their relationship with climate varies over space and time. The growth of phytoplankton and associated marine primary productivity in most of the modern global ocean is limited by the supply of nutrients, including the micronutrient iron. The addition of iron via episodic and frequent events drives the biological carbon pump and promotes the sequestration of atmospheric carbon dioxide (CO2 ) into the ocean. However, the dependence between iron and marine primary producers adaptively changes over different geological periods due to the variation in global climate and environment. In this review, we examined the role and importance of iron in modulating marine primary production during some specific geological periods, that is, the Great Oxidation Event (GOE) during the Huronian glaciation, the Snowball Earth Event during the Cryogenian, the glacial-interglacial cycles during the Pleistocene, and the period from the last glacial maximum to the late Holocene. Only the change trend of iron bioavailability and climate in the glacial-interglacial cycles is consistent with the Iron Hypothesis. During the GOE and the Snowball Earth periods, although the bioavailability of iron in the ocean and the climate changed dramatically, the changing trend of many factors contradicted the Iron Hypothesis. By detangling the relationship among marine primary productivity, iron availability and oceanic environments in different geological periods, this review can offer some new insights for evaluating the impact of ocean iron fertilization on removing CO2 from the atmosphere and regulating the climate.
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Affiliation(s)
- Hai-Bo Jiang
- Key Laboratory of Marine Biotechnology of Zhejiang Province, School of Marine Sciences, Ningbo University, Ningbo, Zhejiang, China
- State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, Zhejiang, China
- Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, Guangdong, China
| | - David A Hutchins
- Department of Biological Sciences, University of Southern California, Los Angeles, California, USA
| | - Wentao Ma
- State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, Zhejiang, China
| | - Rui-Feng Zhang
- School of Oceanography, Shanghai Jiaotong University, Shanghai, Shanghai, China
| | - Mark Wells
- State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, Zhejiang, China
- School of Marine Sciences, University of Maine, Orono, Maine, USA
| | - Nianzhi Jiao
- State Key Laboratory of Marine Environmental Sciences, Xiamen University, Xiamen, Fujian, China
| | - Yuntao Wang
- State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, Zhejiang, China
| | - Fei Chai
- State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, Zhejiang, China
- State Key Laboratory of Marine Environmental Sciences, Xiamen University, Xiamen, Fujian, China
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6
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A Review on a Hidden Gem: Phycoerythrin from Blue-Green Algae. Mar Drugs 2022; 21:md21010028. [PMID: 36662201 PMCID: PMC9863059 DOI: 10.3390/md21010028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 12/21/2022] [Accepted: 12/24/2022] [Indexed: 12/31/2022] Open
Abstract
Phycoerythrin (PE) is a pink/red-colored pigment found in rhodophytes, cryptophytes, and blue-green algae (cyanobacteria). The interest in PE is emerging from its role in delivering health benefits. Unfortunately, the current cyanobacterial-PE (C-PE) knowledge is still in the infant stage. It is essential to acquire a more comprehensive understanding of C-PE. This study aimed to review the C-PE structure, up and downstream processes of C-PE, application of C-PE, and strategies to enhance its stability and market value. In addition, this study also presented a strengths, weaknesses, opportunities, and threats (SWOT) analysis on C-PE. Cyanobacteria appeared to be the more promising PE producers compared to rhodophytes, cryptophytes, and macroalgae. Green/blue light is preferred to accumulate higher PE content in cyanobacteria. Currently, the prominent C-PE extraction method is repeated freezing-thawing. A combination of precipitation and chromatography approaches is proposed to obtain greater purity of C-PE. C-PE has been widely exploited in various fields, such as nutraceuticals, pharmaceuticals, therapeutics, cosmetics, biotechnology, food, and feed, owing to its bioactivities and fluorescent properties. This review provides insight into the state-of-art nature of C-PE and advances a step further in commercializing this prospective pigment.
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7
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Phosphate limitation intensifies negative effects of ocean acidification on globally important nitrogen fixing cyanobacterium. Nat Commun 2022; 13:6730. [PMID: 36344528 PMCID: PMC9640675 DOI: 10.1038/s41467-022-34586-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 10/28/2022] [Indexed: 11/11/2022] Open
Abstract
Growth of the prominent nitrogen-fixing cyanobacterium Trichodesmium is often limited by phosphorus availability in the ocean. How nitrogen fixation by phosphorus-limited Trichodesmium may respond to ocean acidification remains poorly understood. Here, we use phosphate-limited chemostat experiments to show that acidification enhanced phosphorus demands and decreased phosphorus-specific nitrogen fixation rates in Trichodesmium. The increased phosphorus requirements were attributed primarily to elevated cellular polyphosphate contents, likely for maintaining cytosolic pH homeostasis in response to acidification. Alongside the accumulation of polyphosphate, decreased NADP(H):NAD(H) ratios and impaired chlorophyll synthesis and energy production were observed under acidified conditions. Consequently, the negative effects of acidification were amplified compared to those demonstrated previously under phosphorus sufficiency. Estimating the potential implications of this finding, using outputs from the Community Earth System Model, predicts that acidification and dissolved inorganic and organic phosphorus stress could synergistically cause an appreciable decrease in global Trichodesmium nitrogen fixation by 2100.
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8
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Qiu H, Fan P, Hou G, Li X, Wang Y. Analysis and Model Comparison of Carbon and Nitrogen Concentrations in Sediments of the Yellow Sea and Bohai Sea by Visible-Near Infrared Spectroscopy. BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2022; 108:1124-1131. [PMID: 35064279 DOI: 10.1007/s00128-021-03456-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2021] [Accepted: 12/30/2021] [Indexed: 06/14/2023]
Abstract
Visible-near infrared spectroscopy is considered an effective method for rapidly determining total carbon (TC) and total nitrogen (TN) in terrestrial soils. However, reports on measuring them by VNIR in marine sediments are limited. This article provides an analysis and spectral model comparison of TC and TN in marine sediments using VNIR. The best TC and TN spectral models were established when using the least square support vector machine algorithm with a wavelength, which extended from 226 nm to 975 nm. The prediction results of TN have a high coefficient of determination and residual predictive deviation, providing accurate quantitative predictions. The TC spectral model comes with a disadvantage might due to its usual high concentrations of organic carbon. Characteristic wavelength extraction may lead to the loss of identification information for the characteristics of TC and TN, and full wavelength spectrum contains more information helps more to the quantification.
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Affiliation(s)
- Huimin Qiu
- Institute of Oceanographic Instrumentation, Qilu University of Technology (Shandong Academy of Sciences), Qingdao, 266061, China
- Shandong Provincial Key Laboratory of Marine Monitoring Instrument and Equipment Technology, Qingdao, 266061, China
- School of Ocean Technology Sciences, Qilu University of Technology (Shandong Academy of Sciences), Qingdao, 266061, China
| | - Pingping Fan
- Institute of Oceanographic Instrumentation, Qilu University of Technology (Shandong Academy of Sciences), Qingdao, 266061, China
- Shandong Provincial Key Laboratory of Marine Monitoring Instrument and Equipment Technology, Qingdao, 266061, China
- School of Ocean Technology Sciences, Qilu University of Technology (Shandong Academy of Sciences), Qingdao, 266061, China
| | - Guangli Hou
- Institute of Oceanographic Instrumentation, Qilu University of Technology (Shandong Academy of Sciences), Qingdao, 266061, China
- Shandong Provincial Key Laboratory of Marine Monitoring Instrument and Equipment Technology, Qingdao, 266061, China
- School of Ocean Technology Sciences, Qilu University of Technology (Shandong Academy of Sciences), Qingdao, 266061, China
| | - Xueying Li
- Institute of Oceanographic Instrumentation, Qilu University of Technology (Shandong Academy of Sciences), Qingdao, 266061, China.
- Shandong Provincial Key Laboratory of Marine Monitoring Instrument and Equipment Technology, Qingdao, 266061, China.
- School of Ocean Technology Sciences, Qilu University of Technology (Shandong Academy of Sciences), Qingdao, 266061, China.
| | - Yinglong Wang
- Institute of Oceanographic Instrumentation, Qilu University of Technology (Shandong Academy of Sciences), Qingdao, 266061, China.
- Shandong Provincial Key Laboratory of Marine Monitoring Instrument and Equipment Technology, Qingdao, 266061, China.
- School of Ocean Technology Sciences, Qilu University of Technology (Shandong Academy of Sciences), Qingdao, 266061, China.
- Qilu University of Technology (Shandong Academy of Sciences), Jinan, 250353, China.
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Alcamán-Arias ME, Cifuentes-Anticevic J, Castillo-Inaipil W, Farías L, Sanhueza C, Fernández-Gómez B, Verdugo J, Abarzua L, Ridley C, Tamayo-Leiva J, Díez B. Dark Diazotrophy during the Late Summer in Surface Waters of Chile Bay, West Antarctic Peninsula. Microorganisms 2022; 10:microorganisms10061140. [PMID: 35744658 PMCID: PMC9227844 DOI: 10.3390/microorganisms10061140] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 05/28/2022] [Accepted: 05/29/2022] [Indexed: 11/16/2022] Open
Abstract
Although crucial for the addition of new nitrogen in marine ecosystems, dinitrogen (N2) fixation remains an understudied process, especially under dark conditions and in polar coastal areas, such as the West Antarctic Peninsula (WAP). New measurements of light and dark N2 fixation rates in parallel with carbon (C) fixation rates, as well as analysis of the genetic marker nifH for diazotrophic organisms, were conducted during the late summer in the coastal waters of Chile Bay, South Shetland Islands, WAP. During six late summers (February 2013 to 2019), Chile Bay was characterized by high NO3− concentrations (~20 µM) and an NH4+ content that remained stable near 0.5 µM. The N:P ratio was approximately 14.1, thus close to that of the Redfield ratio (16:1). The presence of Cluster I and Cluster III nifH gene sequences closely related to Alpha-, Delta- and, to a lesser extent, Gammaproteobacteria, suggests that chemosynthetic and heterotrophic bacteria are primarily responsible for N2 fixation in the bay. Photosynthetic carbon assimilation ranged from 51.18 to 1471 nmol C L−1 d−1, while dark chemosynthesis ranged from 9.24 to 805 nmol C L−1 d−1. N2 fixation rates were higher under dark conditions (up to 45.40 nmol N L−1 d−1) than under light conditions (up to 7.70 nmol N L−1 d−1), possibly contributing more than 37% to new nitrogen-based production (≥2.5 g N m−2 y−1). Of all the environmental factors measured, only PO43- exhibited a significant correlation with C and N2 rates, being negatively correlated (p < 0.05) with dark chemosynthesis and N2 fixation under the light condition, revealing the importance of the N:P ratio for these processes in Chile Bay. This significant contribution of N2 fixation expands the ubiquity and biological potential of these marine chemosynthetic diazotrophs. As such, this process should be considered along with the entire N cycle when further reviewing highly productive Antarctic coastal waters and the diazotrophic potential of the global marine ecosystem.
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Affiliation(s)
- María E. Alcamán-Arias
- Departamento de Oceanografía, Universidad de Concepción, Concepción 4030000, Chile; (M.E.A.-A.); (L.F.); (L.A.)
- Center for Climate and Resilience Research (CR)2, Universidad de Chile, Blanco Encalada 2002, Santiago 8320000, Chile; (C.R.); (J.T.-L.)
- Escuela de Medicina, Universidad Espíritu Santo, Guayaquil 0901952, Ecuador
| | - Jerónimo Cifuentes-Anticevic
- Departamento de Genética Molecular y Microbiología, Pontificia Universidad Católica de Chile, Santiago 8331150, Chile; (J.C.-A.); (W.C.-I.); (C.S.); (B.F.-G.)
| | - Wilson Castillo-Inaipil
- Departamento de Genética Molecular y Microbiología, Pontificia Universidad Católica de Chile, Santiago 8331150, Chile; (J.C.-A.); (W.C.-I.); (C.S.); (B.F.-G.)
| | - Laura Farías
- Departamento de Oceanografía, Universidad de Concepción, Concepción 4030000, Chile; (M.E.A.-A.); (L.F.); (L.A.)
- Center for Climate and Resilience Research (CR)2, Universidad de Chile, Blanco Encalada 2002, Santiago 8320000, Chile; (C.R.); (J.T.-L.)
| | - Cynthia Sanhueza
- Departamento de Genética Molecular y Microbiología, Pontificia Universidad Católica de Chile, Santiago 8331150, Chile; (J.C.-A.); (W.C.-I.); (C.S.); (B.F.-G.)
| | - Beatriz Fernández-Gómez
- Departamento de Genética Molecular y Microbiología, Pontificia Universidad Católica de Chile, Santiago 8331150, Chile; (J.C.-A.); (W.C.-I.); (C.S.); (B.F.-G.)
- Instituto de Oceanografía y Cambio Global (IOCAG), Universidad de Las Palmas de Gran Canaria (ULPGC), 35001 Las Palmas, Spain
| | - Josefa Verdugo
- Alfred-Wegener-Institute, Helmholtz Centre for Polar and Marine Research, 27570 Bremerhaven, Germany;
| | - Leslie Abarzua
- Departamento de Oceanografía, Universidad de Concepción, Concepción 4030000, Chile; (M.E.A.-A.); (L.F.); (L.A.)
| | - Christina Ridley
- Center for Climate and Resilience Research (CR)2, Universidad de Chile, Blanco Encalada 2002, Santiago 8320000, Chile; (C.R.); (J.T.-L.)
- Departamento de Genética Molecular y Microbiología, Pontificia Universidad Católica de Chile, Santiago 8331150, Chile; (J.C.-A.); (W.C.-I.); (C.S.); (B.F.-G.)
| | - Javier Tamayo-Leiva
- Center for Climate and Resilience Research (CR)2, Universidad de Chile, Blanco Encalada 2002, Santiago 8320000, Chile; (C.R.); (J.T.-L.)
- Departamento de Genética Molecular y Microbiología, Pontificia Universidad Católica de Chile, Santiago 8331150, Chile; (J.C.-A.); (W.C.-I.); (C.S.); (B.F.-G.)
- Center for Genome Regulation (CRG), Universidad de Chile, Blanco Encalada 2085, Santiago 8320000, Chile
| | - Beatriz Díez
- Center for Climate and Resilience Research (CR)2, Universidad de Chile, Blanco Encalada 2002, Santiago 8320000, Chile; (C.R.); (J.T.-L.)
- Departamento de Genética Molecular y Microbiología, Pontificia Universidad Católica de Chile, Santiago 8331150, Chile; (J.C.-A.); (W.C.-I.); (C.S.); (B.F.-G.)
- Center for Genome Regulation (CRG), Universidad de Chile, Blanco Encalada 2085, Santiago 8320000, Chile
- Correspondence:
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10
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Bannon C, Rapp I, Bertrand EM. Community Interaction Co-limitation: Nutrient Limitation in a Marine Microbial Community Context. Front Microbiol 2022; 13:846890. [PMID: 35711751 PMCID: PMC9196195 DOI: 10.3389/fmicb.2022.846890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Accepted: 03/29/2022] [Indexed: 11/20/2022] Open
Abstract
The simultaneous limitation of productivity by two or more nutrients, commonly referred to as nutrient co-limitation, affects microbial communities throughout the marine environment and is of profound importance because of its impacts on various biogeochemical cycles. Multiple types of co-limitation have been described, enabling distinctions based on the hypothesized mechanisms of co-limitation at a biochemical level. These definitions usually pertain to individuals and do not explicitly, or even implicitly, consider complex ecological dynamics found within a microbial community. However, limiting and co-limiting nutrients can be produced in situ by a subset of microbial community members, suggesting that interactions within communities can underpin co-limitation. To address this, we propose a new category of nutrient co-limitation, community interaction co-limitation (CIC). During CIC, one part of the community is limited by one nutrient, which results in the insufficient production or transformation of a biologically produced nutrient that is required by another part of the community, often primary producers. Using cobalamin (vitamin B12) and nitrogen fixation as our models, we outline three different ways CIC can arise based on current literature and discuss CIC’s role in biogeochemical cycles. Accounting for the inherent and complex roles microbial community interactions play in generating this type of co-limitation requires an expanded toolset – beyond the traditional approaches used to identify and study other types of co-limitation. We propose incorporating processes and theories well-known in microbial ecology and evolution to provide meaningful insight into the controls of community-based feedback loops and mechanisms that give rise to CIC in the environment. Finally, we highlight the data gaps that limit our understanding of CIC mechanisms and suggest methods to overcome these and further identify causes and consequences of CIC. By providing this framework for understanding and identifying CIC, we enable systematic examination of the impacts this co-limitation can have on current and future marine biogeochemical processes.
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Affiliation(s)
- Catherine Bannon
- Department of Biology and Institute for Comparative Genomics, Dalhousie University, Halifax, NS, Canada
| | - Insa Rapp
- Department of Biology and Institute for Comparative Genomics, Dalhousie University, Halifax, NS, Canada
- Marine Biogeochemistry Division, GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
| | - Erin M. Bertrand
- Department of Biology and Institute for Comparative Genomics, Dalhousie University, Halifax, NS, Canada
- *Correspondence: Erin M. Bertrand,
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11
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Rabouille S, Tournier L, Duhamel S, Claquin P, Crispi O, Talec A, Landolfi A, Oschlies A. Organic Phosphorus Scavenging Supports Efficient Growth of Diazotrophic Cyanobacteria Under Phosphate Depletion. Front Microbiol 2022; 13:848647. [PMID: 35401448 PMCID: PMC8990761 DOI: 10.3389/fmicb.2022.848647] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 03/03/2022] [Indexed: 11/29/2022] Open
Abstract
Considering the reported significant diazotrophic activities in open-ocean regions where primary production is strongly limited by phosphate, we explored the ability of diazotrophs to use other sources of phosphorus to alleviate the phosphate depletion. We tested the actual efficiency of the open-ocean, N2-fixer Crocosphaera watsonii to grow on organic phosphorus as the sole P source, and observed how the P source affects the cellular C, N, and P composition. We obtained equivalent growth efficiencies on AMP and DL-α-glycerophosphate as compared with identical cultures grown on phosphate, and survival of the population on phytic acid. Our results show that Crocosphaera cannot use all phosphomonoesters with the same efficiency, but it can grow without phosphate, provided that usable DOP and sufficient light energy are available. Also, results point out that organic phosphorus uptake is not proportional to alkaline phosphatase activity, demonstrating that the latter is not a suitable proxy to estimate DOP-based growth yields of organisms, whether in culture experiments or in the natural environment. The growth parameters obtained, as a function of the P source, will be critical to improve and calibrate mathematical models of diazotrophic growth and the distribution of nitrogen fixation in the global ocean.
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Affiliation(s)
- Sophie Rabouille
- Laboratoire d'Océanographie de Villefranche (LOV), CNRS, Sorbonne Université, Villefranche-sur-Mer, France.,Laboratoire d'Océanographie Microbienne (LOMIC), CNRS, Sorbonne Université, Banyuls-sur-Mer, France
| | - Lauralie Tournier
- Laboratoire d'Océanographie de Villefranche (LOV), CNRS, Sorbonne Université, Villefranche-sur-Mer, France
| | - Solange Duhamel
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ, United States
| | - Pascal Claquin
- UMR BOREA (CNRS 8067), MNHN, IRD (207), Normandie Université, Université de Caen Normandie, CREC, Luc-sur-Mer, France
| | - Olivier Crispi
- Laboratoire d'Océanographie Microbienne (LOMIC), CNRS, Sorbonne Université, Banyuls-sur-Mer, France
| | - Amélie Talec
- Laboratoire d'Océanographie de Villefranche (LOV), CNRS, Sorbonne Université, Villefranche-sur-Mer, France
| | - Angela Landolfi
- GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany.,CNR ISMAR, Rome, Italy
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12
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Dai M, Wang T, Wang Y, Xu J. Effects of Warming and Phosphorus Enrichment on the C:N:P Stoichiometry of Potamogeton crispus Organs. FRONTIERS IN PLANT SCIENCE 2022; 13:814255. [PMID: 35422837 PMCID: PMC9002266 DOI: 10.3389/fpls.2022.814255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/13/2021] [Accepted: 02/25/2022] [Indexed: 06/14/2023]
Abstract
The loss of submerged macrophytes from freshwater ecosystems is accelerating owing to the combined effects of eutrophication and climate change. Submerged macrophytes depend on spring clear water; however, increased water temperatures and excessive phosphorus (P) inputs often lead to the dominance of phytoplankton. It is still not clear how the stoichiometric characteristics of carbon (C), nitrogen (N), and P in different tissues of submerged macrophytes respond to P enrichment and temperature increases. In this study, we established 36 mesocosm ecosystems to explore the effects of warming and P addition on the leaf, turion, stem, and seed stoichiometry of Potamogeton crispus. The results revealed that different functional plant organs show distinct responses to P addition and warming, which demonstrates the importance of evaluating the responses of different submerged macrophyte organs to environmental changes. In addition, interactive effects between P addition and warming were observed in the leaf, turion, and seed C:N:P stoichiometry, which highlights the importance of multifactorial studies. Our data showed that warming caused a decrease in the C content in most organs, with the exception of the stem; P addition increased the P content in most organs, with the exception of seed; N content in the turion and seed were influenced by interactive effects. Collectively, P addition could help P. crispus to resist the adverse effects of high temperatures by aiding growth and asexual reproduction, and asexual propagules were found to be more sensitive to P enrichment than sexual propagules.
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Affiliation(s)
- Mingzhe Dai
- School of Ecology and Nature Conservation, Beijing Forestry University, Beijing, China
| | - Tao Wang
- Donghu Experimental Station of Lake Ecosystems, State Key Laboratory of Freshwater Ecology and Biotechnology of China, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Yuyu Wang
- School of Ecology and Nature Conservation, Beijing Forestry University, Beijing, China
| | - Jun Xu
- Donghu Experimental Station of Lake Ecosystems, State Key Laboratory of Freshwater Ecology and Biotechnology of China, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
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13
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Acker M, Hogle SL, Berube PM, Hackl T, Coe A, Stepanauskas R, Chisholm SW, Repeta DJ. Phosphonate production by marine microbes: Exploring new sources and potential function. Proc Natl Acad Sci U S A 2022; 119:e2113386119. [PMID: 35254902 PMCID: PMC8931226 DOI: 10.1073/pnas.2113386119] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Accepted: 01/20/2022] [Indexed: 12/12/2022] Open
Abstract
SignificancePhosphonates are a class of phosphorus metabolites characterized by a highly stable C-P bond. Phosphonates accumulate to high concentrations in seawater, fuel a large fraction of marine methane production, and serve as a source of phosphorus to microbes inhabiting nutrient-limited regions of the oligotrophic ocean. Here, we show that 15% of all bacterioplankton in the surface ocean have genes phosphonate synthesis and that most belong to the abundant groups Prochlorococcus and SAR11. Genomic and chemical evidence suggests that phosphonates are incorporated into cell-surface phosphonoglycoproteins that may act to mitigate cell mortality by grazing and viral lysis. These results underscore the large global biogeochemical impact of relatively rare but highly expressed traits in numerically abundant groups of marine bacteria.
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Affiliation(s)
- Marianne Acker
- Massachusetts Institute of Technology-Woods Hole Oceanographic Institution Joint Program in Oceanography/Applied Ocean Science and Engineering, Woods Hole Oceanographic Institution, Woods Hole, MA 02543
- Department of Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA 02543
| | - Shane L. Hogle
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
- Department of Biology, University of Turku, Turku 20500, Finland
| | - Paul M. Berube
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Thomas Hackl
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Allison Coe
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Ramunas Stepanauskas
- Single Cell Genomics Center, Bigelow Laboratory for Ocean Sciences, East Boothbay, ME 04544
| | - Sallie W. Chisholm
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Daniel J. Repeta
- Department of Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA 02543
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14
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Fernández-Juárez V, Jaén-Luchoro D, Brito-Echeverría J, Agawin NSR, Bennasar-Figueras A, Echeveste P. Everything Is Everywhere: Physiological Responses of the Mediterranean Sea and Eastern Pacific Ocean Epiphyte Cobetia Sp. to Varying Nutrient Concentration. MICROBIAL ECOLOGY 2022; 83:296-313. [PMID: 33954842 DOI: 10.1007/s00248-021-01766-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2020] [Accepted: 04/22/2021] [Indexed: 06/12/2023]
Abstract
Bacteria are essential in the maintenance and sustainment of marine environments (e.g., benthic systems), playing a key role in marine food webs and nutrient cycling. These microorganisms can live associated as epiphytic or endophytic populations with superior organisms with valuable ecological functions, e.g., seagrasses. Here, we isolated, identified, sequenced, and exposed two strains of the same species (i.e., identified as Cobetia sp.) from two different marine environments to different nutrient regimes using batch cultures: (1) Cobetia sp. UIB 001 from the endemic Mediterranean seagrass Posidonia oceanica and (2) Cobetia sp. 4B UA from the endemic Humboldt Current System (HCS) seagrass Heterozostera chilensis. From our physiological studies, both strains behaved as bacteria capable to cope with different nutrient and pH regimes, i.e., N, P, and Fe combined with different pH levels, both in long-term (12 days (d)) and short-term studies (4 d/96 h (h)). We showed that the isolated strains were sensitive to the N source (inorganic and organic) at low and high concentrations and low pH levels. Low availability of phosphorus (P) and Fe had a negative independent effect on growth, especially in the long-term studies. The strain UIB 001 showed a better adaptation to low nutrient concentrations, being a potential N2-fixer, reaching higher growth rates (μ) than the HCS strain. P-acquisition mechanisms were deeply investigated at the enzymatic (i.e., alkaline phosphatase activity, APA) and structural level (e.g., alkaline phosphatase D, PhoD). Finally, these results were complemented with the study of biochemical markers, i.e., reactive oxygen species (ROS). In short, we present how ecological niches (i.e., MS and HCS) might determine, select, and modify the genomic and phenotypic features of the same bacterial species (i.e., Cobetia spp.) found in different marine environments, pointing to a direct correlation between adaptability and oligotrophy of seawater.
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Affiliation(s)
- Víctor Fernández-Juárez
- Marine Ecology and Systematics (MarES), Department of Biology, University of the Balearic Islands, Palma, Spain.
| | - Daniel Jaén-Luchoro
- Department of Infectious Diseases, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
- Culture Collection University of Gothenburg (CCUG), Sahlgrenska Academy of the University of Gothenburg, Gothenburg, Sweden
| | - Jocelyn Brito-Echeverría
- Instituto de Ciencias Naturales Alexander von Humboldt, Universidad de Antofagasta, Antofagasta, Chile
| | - Nona S R Agawin
- Marine Ecology and Systematics (MarES), Department of Biology, University of the Balearic Islands, Palma, Spain
| | | | - Pedro Echeveste
- Instituto de Ciencias Naturales Alexander von Humboldt, Universidad de Antofagasta, Antofagasta, Chile
- Instituto Milenio de Oceanografía, Concepción, Chile
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15
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Wang S, Koedooder C, Zhang F, Kessler N, Eichner M, Shi D, Shaked Y. Colonies of the marine cyanobacterium Trichodesmium optimize dust utilization by selective collection and retention of nutrient-rich particles. iScience 2022; 25:103587. [PMID: 35005537 PMCID: PMC8718973 DOI: 10.1016/j.isci.2021.103587] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 10/01/2021] [Accepted: 12/06/2021] [Indexed: 12/11/2022] Open
Abstract
Trichodesmium, a globally important, N2-fixing, and colony-forming cyanobacterium, employs multiple pathways for acquiring nutrients from air-borne dust, including active dust collection. Once concentrated within the colony core, dust can supply Trichodesmium with nutrients. Recently, we reported a selectivity in particle collection enabling Trichodesmium to center iron-rich minerals and optimize its nutrient utilization. In this follow-up study we examined if colonies select Phosphorus (P) minerals. We incubated 1,200 Trichodesmium colonies from the Red Sea with P-free CaCO3, P-coated CaCO3, and dust, over an entire bloom season. These colonies preferably interacted, centered, and retained P-coated CaCO3 compared with P-free CaCO3. In both studies, Trichodesmium clearly favored dust over all other particles tested, whereas nutrient-free particles were barely collected or retained, indicating that the colonies sense the particle composition and preferably collect nutrient-rich particles. This unique ability contributes to Trichodesmium's current ecological success and may assist it to flourish in future warmer oceans. Natural Trichodesmium colonies collect and maintain dust within their colony core Using synthetic particles we tested if colonies select the particles they collect Colonies selectively collect and retain nutrient-rich over nutrient-free particles Selective collection of particles optimizes their nutrient acquisition from dust
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Affiliation(s)
- Siyuan Wang
- The Freddy and Nadine Herrmann Institute of Earth Sciences, Edmond J. Safra Campus, Givat Ram, Hebrew University of Jerusalem, Jerusalem, Israel.,The Interuniversity Institute for Marine Sciences in Eilat, Eilat, Israel
| | - Coco Koedooder
- The Freddy and Nadine Herrmann Institute of Earth Sciences, Edmond J. Safra Campus, Givat Ram, Hebrew University of Jerusalem, Jerusalem, Israel.,The Interuniversity Institute for Marine Sciences in Eilat, Eilat, Israel.,Israel Limnology and Oceanography Research, Haifa, Israel
| | - Futing Zhang
- The Freddy and Nadine Herrmann Institute of Earth Sciences, Edmond J. Safra Campus, Givat Ram, Hebrew University of Jerusalem, Jerusalem, Israel.,The Interuniversity Institute for Marine Sciences in Eilat, Eilat, Israel.,State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, Fujian, People's Republic of China
| | - Nivi Kessler
- The Freddy and Nadine Herrmann Institute of Earth Sciences, Edmond J. Safra Campus, Givat Ram, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Meri Eichner
- Laboratory of Photosynthesis, Center Algatech, Institute of Microbiology of the Czech Academy of Sciences, Třeboň, Czech Republic
| | - Dalin Shi
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, Fujian, People's Republic of China
| | - Yeala Shaked
- The Freddy and Nadine Herrmann Institute of Earth Sciences, Edmond J. Safra Campus, Givat Ram, Hebrew University of Jerusalem, Jerusalem, Israel.,The Interuniversity Institute for Marine Sciences in Eilat, Eilat, Israel
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16
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Walworth NG, Saito MA, Lee MD, McIlvin MR, Moran DM, Kellogg RM, Fu FX, Hutchins DA, Webb EA. Why Environmental Biomarkers Work: Transcriptome-Proteome Correlations and Modeling of Multistressor Experiments in the Marine Bacterium Trichodesmium. J Proteome Res 2021; 21:77-89. [PMID: 34855411 DOI: 10.1021/acs.jproteome.1c00517] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Ocean microbial communities are important contributors to the global biogeochemical reactions that sustain life on Earth. The factors controlling these communities are being increasingly explored using metatranscriptomic and metaproteomic environmental biomarkers. Using published proteomes and transcriptomes from the abundant colony-forming cyanobacterium Trichodesmium (strain IMS101) grown under varying Fe and/or P limitation in low and high CO2, we observed robust correlations of stress-induced proteins and RNAs (i.e., involved in transport and homeostasis) that yield useful information on the nutrient status under low and/or high CO2. Conversely, transcriptional and translational correlations of many other central metabolism pathways exhibit broad discordance. A cellular RNA and protein production/degradation model demonstrates how biomolecules with small initial inventories, such as environmentally responsive proteins, achieve large increases in fold-change units as opposed to those with a higher basal expression and inventory such as metabolic systems. Microbial cells, due to their immersion in the environment, tend to show large adaptive responses in both RNA and protein that result in transcript-protein correlations. These observations and model results demonstrate multi-omic coherence for environmental biomarkers and provide the underlying mechanism for those observations, supporting the promise for global application in detecting responses to environmental stimuli in a changing ocean.
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Affiliation(s)
- Nathan G Walworth
- Marine and Environmental Biology, Department of Biological Sciences, University of Southern California, Los Angeles, California 90089, United States
| | - Mak A Saito
- Marine Chemistry and Geochemistry Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, United States
| | - Michael D Lee
- Blue Marble Space Institute of Science, Seattle, Washington 98104, United States.,Exobiology Branch, NASA Ames Research Center, Moffett Field, California 94035, United States
| | - Matthew R McIlvin
- Marine Chemistry and Geochemistry Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, United States
| | - Dawn M Moran
- Marine Chemistry and Geochemistry Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, United States
| | - Riss M Kellogg
- Marine Chemistry and Geochemistry Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, United States
| | - Fei-Xue Fu
- Marine and Environmental Biology, Department of Biological Sciences, University of Southern California, Los Angeles, California 90089, United States
| | - David A Hutchins
- Marine and Environmental Biology, Department of Biological Sciences, University of Southern California, Los Angeles, California 90089, United States
| | - Eric A Webb
- Marine and Environmental Biology, Department of Biological Sciences, University of Southern California, Los Angeles, California 90089, United States
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17
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Antell GT, Saupe EE. Bottom-up controls, ecological revolutions and diversification in the oceans through time. Curr Biol 2021; 31:R1237-R1251. [PMID: 34637737 DOI: 10.1016/j.cub.2021.08.069] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Animals originated in the oceans and evolved there for hundreds of millions of years before adapting to terrestrial environments. Today, oceans cover more than two-thirds of Earth and generate as much primary production as land. The path from the first macrobiota to modern marine biodiversity involved parallel increases in terrestrial nutrient input, marine primary production, species' abundance, metabolic rates, ecotypic diversity and taxonomic diversity. Bottom-up theories of ecosystem cascades arrange these changes in a causal sequence. At the base of marine food webs, nutrient fluxes and atmosphere-ocean chemistry interact with phytoplankton to regulate production. First-order consumers (e.g., zooplankton) might propagate changes in quantity and quality of phytoplankton to changes in abundance and diversity of larger predators (e.g., nekton). However, many uncertainties remain about the mechanisms and effect size of bottom-up control, particularly in oceans across the entire history of animal life. Here, we review modern and fossil evidence for hypothesized bottom-up pathways, and we assess the ramifications of these processes for four key intervals in marine ecosystems: the Ediacaran-Cambrian (635-485 million years ago), the Ordovician (485-444 million years ago), the Devonian (419-359 million years ago) and the Mesozoic (252-66 million years ago). We advocate for a clear articulation of bottom-up hypotheses to better understand causal relationships and proposed effects, combined with additional ecological experiments, paleontological documentation, isotope geochemistry and geophysical reconstructions. How small-scale ecological change transitions into large-scale evolutionary change remains an outstanding question for empirical and theoretical research.
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Affiliation(s)
- Gawain T Antell
- Department of Earth Sciences, University of Oxford, Oxford OX1 3AN, UK.
| | - Erin E Saupe
- Department of Earth Sciences, University of Oxford, Oxford OX1 3AN, UK
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18
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Wu C, Sun J, Liu H, Xu W, Zhang G, Lu H, Guo Y. Evidence of the Significant Contribution of Heterotrophic Diazotrophs to Nitrogen Fixation in the Eastern Indian Ocean During Pre-Southwest Monsoon Period. Ecosystems 2021. [DOI: 10.1007/s10021-021-00702-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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19
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Gosselin K, Nelson RK, Spivak AC, Sylva SP, Van Mooy BA, Aeppli C, Sharpless CM, O’Neil GW, Arrington EC, Reddy CM, Valentine DL. Production of Two Highly Abundant 2-Methyl-Branched Fatty Acids by Blooms of the Globally Significant Marine Cyanobacteria Trichodesmium erythraeum. ACS OMEGA 2021; 6:22803-22810. [PMID: 34514251 PMCID: PMC8427776 DOI: 10.1021/acsomega.1c03196] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 08/04/2021] [Indexed: 05/27/2023]
Abstract
The bloom-forming cyanobacteria Trichodesmium contribute up to 30% to the total fixed nitrogen in the global oceans and thereby drive substantial productivity. On an expedition in the Gulf of Mexico, we observed and sampled surface slicks, some of which included dense blooms of Trichodesmium erythraeum. These bloom samples contained abundant and atypical free fatty acids, identified here as 2-methyldecanoic acid and 2-methyldodecanoic acid. The high abundance and unusual branching pattern of these compounds suggest that they may play a specific role in this globally important organism.
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Affiliation(s)
- Kelsey
M. Gosselin
- Interdepartmental
Graduate Program in Marine Science, University
of California, Santa
Barbara, California 93106, United States
| | - Robert K. Nelson
- Department
of Marine Chemistry and Geochemistry, Woods
Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, United States
| | - Amanda C. Spivak
- Department
of Marine Sciences, University of Georgia, Athens, Georgia 30602, United States
| | - Sean P. Sylva
- Department
of Marine Chemistry and Geochemistry, Woods
Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, United States
| | - Benjamin A.S. Van Mooy
- Department
of Marine Chemistry and Geochemistry, Woods
Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, United States
| | - Christoph Aeppli
- Bigelow
Laboratory for Ocean Sciences, East Boothbay, Maine 04544, United States
| | - Charles M. Sharpless
- Andlinger
Center for Energy and the Environment, Princeton
University, Princeton, New Jersey 08544, United States
| | - Gregory W. O’Neil
- Department
of Chemistry, Western Washington University, Bellingham, Washington 98225, United States
| | - Eleanor C. Arrington
- Interdepartmental
Graduate Program in Marine Science, University
of California, Santa
Barbara, California 93106, United States
| | - Christopher M. Reddy
- Department
of Marine Chemistry and Geochemistry, Woods
Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, United States
| | - David L. Valentine
- Department
of Earth Science and Marine Science Institute, University of California, Santa
Barbara, California 93106, United States
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20
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Qiu GW, Lis H, Qiu BS, Keren N. Long-term iron deprivation and subsequent recovery uncover heterogeneity in the response of cyanobacterial populations. Environ Microbiol 2021; 23:1793-1804. [PMID: 33615658 DOI: 10.1111/1462-2920.15443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 02/15/2021] [Accepted: 02/20/2021] [Indexed: 11/29/2022]
Abstract
Cyanobacteria are globally important primary producers and nitrogen fixers. They are frequently limited by iron bioavailability in natural environments that often fluctuate due to rapid consumption and irregular influx of external Fe. Here we identify a succession of physiological changes in Synechocystis sp. PCC 6803 occurring over 14-16 days of iron deprivation and subsequent recovery. We observe several adaptive strategies that allow cells to push their metabolic limits under the restriction of declining intracellular Fe quotas. Interestingly, cyanobacterial populations exposed to prolonged iron deprivation showed discernible heterogeneity in cellular auto-fluorescence during the recovery process. Using FACS and microscopy techniques we revealed that only cells with high auto-fluorescence were able to grow and reconstitute thylakoid membranes. We propose that ROS-mediated damage is likely to be associated with the emergence of the two subpopulations, and, indeed, a rapid increase in intracellular ROS content was observed during the first hours following iron addition to Fe-starved cultures. These results suggest that an increasing iron supply is a double-edged sword - posing both an opportunity and a risk. Therefore, phenotypic heterogeneity within populations is crucial for the survival and proliferation of organisms facing iron fluctuations within natural environments.
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Affiliation(s)
- Guo-Wei Qiu
- Department of Plant and Environmental Sciences, Edmond J. Safra Campus, The Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Givat Ram, Jerusalem, 9190402, Israel.,School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, China
| | - Hagar Lis
- Department of Plant and Environmental Sciences, Edmond J. Safra Campus, The Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Givat Ram, Jerusalem, 9190402, Israel
| | - Bao-Sheng Qiu
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, China
| | - Nir Keren
- Department of Plant and Environmental Sciences, Edmond J. Safra Campus, The Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Givat Ram, Jerusalem, 9190402, Israel
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21
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Messer LF, Brown MV, Van Ruth PD, Doubell M, Seymour JR. Temperate southern Australian coastal waters are characterised by surprisingly high rates of nitrogen fixation and diversity of diazotrophs. PeerJ 2021; 9:e10809. [PMID: 33717676 PMCID: PMC7931716 DOI: 10.7717/peerj.10809] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Accepted: 12/30/2020] [Indexed: 11/20/2022] Open
Abstract
Biological dinitrogen (N2) fixation is one mechanism by which specific microorganisms (diazotrophs) can ameliorate nitrogen (N) limitation. Historically, rates of N2 fixation were believed to be limited outside of the low nutrient tropical and subtropical open ocean; however, emerging evidence suggests that N2 fixation is also a significant process within temperate coastal waters. Using a combination of amplicon sequencing, targeting the nitrogenase reductase gene (nifH), quantitative nifH PCR, and 15N2 stable isotope tracer experiments, we investigated spatial patterns of diazotroph assemblage structure and N2 fixation rates within the temperate coastal waters of southern Australia during Austral autumn and summer. Relative to previous studies in open ocean environments, including tropical northern Australia, and tropical and temperate estuaries, our results indicate that high rates of N2 fixation (10-64 nmol L-1 d-1) can occur within the large inverse estuary Spencer Gulf, while comparatively low rates of N2 fixation (2 nmol L-1 d-1) were observed in the adjacent continental shelf waters. Across the dataset, low concentrations of NO3/NO2 were significantly correlated with the highest N2 fixation rates, suggesting that N2 fixation could be an important source of new N in the region as dissolved inorganic N concentrations are typically limiting. Overall, the underlying diazotrophic community was dominated by nifH sequences from Cluster 1 unicellular cyanobacteria of the UCYN-A clade, as well as non-cyanobacterial diazotrophs related to Pseudomonas stutzeri, and Cluster 3 sulfate-reducing deltaproteobacteria. Diazotroph community composition was significantly influenced by salinity and SiO4 concentrations, reflecting the transition from UCYN-A-dominated assemblages in the continental shelf waters, to Cluster 3-dominated assemblages in the hypersaline waters of the inverse estuary. Diverse, transitional diazotrophic communities, comprised of a mixture of UCYN-A and putative heterotrophic bacteria, were observed at the mouth and southern edge of Spencer Gulf, where the highest N2 fixation rates were observed. In contrast to observations in other environments, no seasonal patterns in N2 fixation rates and diazotroph community structure were apparent. Collectively, our findings are consistent with the emerging view that N2 fixation within temperate coastal waters is a previously overlooked dynamic and potentially important component of the marine N cycle.
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Affiliation(s)
- Lauren F Messer
- Climate Change Cluster, University of Technology Sydney, Sydney, New South Wales, Australia.,Centre for Microbiome Research, School of Biomedical Sciences, Queensland University of Technology, Brisbane, QLD, Australia
| | - Mark V Brown
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, New South Wales, Australia
| | - Paul D Van Ruth
- Aquatic Sciences, South Australian Research and Development Institute, Adelaide, South Australia, Australia
| | - Mark Doubell
- Aquatic Sciences, South Australian Research and Development Institute, Adelaide, South Australia, Australia
| | - Justin R Seymour
- Climate Change Cluster, University of Technology Sydney, Sydney, New South Wales, Australia
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22
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Ares Á, Brisbin MM, Sato KN, Martín JP, Iinuma Y, Mitarai S. Extreme storms cause rapid but short-lived shifts in nearshore subtropical bacterial communities. Environ Microbiol 2021; 22:4571-4588. [PMID: 33448616 DOI: 10.1111/1462-2920.15178] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 06/27/2020] [Accepted: 07/24/2020] [Indexed: 01/04/2023]
Abstract
Climate change scenarios predict tropical cyclones will increase in both frequency and intensity, which will escalate the amount of terrestrial run-off and mechanical disruption affecting coastal ecosystems. Bacteria are key contributors to ecosystem functioning, but relatively little is known about how they respond to extreme storm events, particularly in nearshore subtropical regions. In this study, we combine field observations and mesocosm experiments to assess bacterial community dynamics and changes in physicochemical properties during early- and late-season tropical cyclones affecting Okinawa, Japan. Storms caused large and fast influxes of freshwater and terrestrial sediment - locally known as red soil pollution - and caused moderate increases of macronutrients, especially SiO2 and PO4 3-, with up to 25 and 0.5 μM respectively. We detected shifts in relative abundances of marine and terrestrially derived bacteria, including putative coral and human pathogens, during storm events. Soil input alone did not substantially affect marine bacterial communities in mesocosms, indicating that other components of run-off or other storm effects likely exert a larger influence on bacterial communities. The storm effects were short-lived and bacterial communities quickly recovered following both storm events. The early- and late-season storms caused different physicochemical and bacterial community changes, demonstrating the context-dependency of extreme storm responses in a subtropical coastal ecosystem.
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Affiliation(s)
- Ángela Ares
- Marine Biophysics Unit, Okinawa Institute of Science and Technology (OIST), Okinawa, Japan
| | - Margaret Mars Brisbin
- Marine Biophysics Unit, Okinawa Institute of Science and Technology (OIST), Okinawa, Japan
| | - Kirk N Sato
- Marine Biophysics Unit, Okinawa Institute of Science and Technology (OIST), Okinawa, Japan.,Friday Harbor Laboratories, University of Washington, WA, USA
| | - Juan P Martín
- Marine Biophysics Unit, Okinawa Institute of Science and Technology (OIST), Okinawa, Japan
| | - Yoshiteru Iinuma
- Instrumental Analysis Section, Okinawa Institute of Science and Technology (OIST), Okinawa, Japan
| | - Satoshi Mitarai
- Marine Biophysics Unit, Okinawa Institute of Science and Technology (OIST), Okinawa, Japan
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23
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Inomura K, Deutsch C, Masuda T, Prášil O, Follows MJ. Quantitative models of nitrogen-fixing organisms. Comput Struct Biotechnol J 2020; 18:3905-3924. [PMID: 33335688 PMCID: PMC7733014 DOI: 10.1016/j.csbj.2020.11.022] [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: 08/28/2020] [Revised: 11/11/2020] [Accepted: 11/13/2020] [Indexed: 10/26/2022] Open
Abstract
Nitrogen-fixing organisms are of importance to the environment, providing bioavailable nitrogen to the biosphere. Quantitative models have been used to complement the laboratory experiments and in situ measurements, where such evaluations are difficult or costly. Here, we review the current state of the quantitative modeling of nitrogen-fixing organisms and ways to enhance the bridge between theoretical and empirical studies.
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Affiliation(s)
- Keisuke Inomura
- School of Oceanography, University of Washington, Seattle, WA, USA
| | - Curtis Deutsch
- School of Oceanography, University of Washington, Seattle, WA, USA
| | - Takako Masuda
- Institute of Microbiology, The Czech Academy of Sciences, Opatovický mlýn, Třeboň, Czech Republic
| | - Ondřej Prášil
- Institute of Microbiology, The Czech Academy of Sciences, Opatovický mlýn, Třeboň, Czech Republic
| | - Michael J. Follows
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
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24
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Fernández-Juárez V, Bennasar-Figueras A, Sureda-Gomila A, Ramis-Munar G, Agawin NSR. Differential Effects of Varying Concentrations of Phosphorus, Iron, and Nitrogen in N 2-Fixing Cyanobacteria. Front Microbiol 2020; 11:541558. [PMID: 33101223 PMCID: PMC7546424 DOI: 10.3389/fmicb.2020.541558] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 08/18/2020] [Indexed: 12/02/2022] Open
Abstract
Diazotrophs or N2-fixers are one of the most ecologically significant groups in marine ecosystems (pelagic and benthic). Inorganic phosphorus (PO43–) and iron (Fe) can limit the growth and N2-fixing capacities of cyanobacteria. However, studies investigating co-limitation of these factors are lacking. Here, we added different concentrations of PO43– and Fe in two cyanobacterial species whose relatives can be found in seagrass habitats: the unicellular Halothece sp. (PCC 7418) and the filamentous Fischerella muscicola (PCC 73103), grown under different nitrate (NO3–) concentrations and under N2 as sole N source, respectively. Their growth, pigment content, N2-fixation rates, oxidative stress responses, and morphological and cellular changes were investigated. Our results show a serial limitation of NO3– and PO43– (with NO3– as the primary limiting nutrient) for Halothece sp. Simultaneous co-limitation of PO43– and Fe was found for both species tested, and high levels of Fe (especially when added with high PO43– levels) inhibited the growth of Halothece sp. Nutrient limitation (PO43–, Fe, and/or NO3–) enhanced oxidative stress responses, morphological changes, and apoptosis. Furthermore, an extensive bio-informatic analysis describing the predicted Pho, Fur, and NtcA regulons (involved in the survival of cells to P, Fe, and N limitation) was made using the complete genome of Halothece sp. as a model, showing the potential of this strain to adapt to different nutrient regimes (P, Fe, or N).
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Affiliation(s)
- Víctor Fernández-Juárez
- Marine Ecology and Systematics (MarES), Department of Biology, University of the Balearic Islands, Palma, Spain
| | | | - Antoni Sureda-Gomila
- Research Group on Community Nutrition and Oxidative Stress, University of the Balearic Islands and CIBEROBN (Fisiopatología de la Obesidad y la Nutrición), Palma, Spain
| | - Guillem Ramis-Munar
- Cellomic Unit of University Institute of Research in Health Sciences of the Balearic Islands, Palma, Spain
| | - Nona S R Agawin
- Marine Ecology and Systematics (MarES), Department of Biology, University of the Balearic Islands, Palma, Spain
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25
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Surviving Starvation: Proteomic and Lipidomic Profiling of Nutrient Deprivation in the Smallest Known Free-Living Eukaryote. Metabolites 2020; 10:metabo10070273. [PMID: 32635273 PMCID: PMC7407893 DOI: 10.3390/metabo10070273] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 06/17/2020] [Accepted: 06/27/2020] [Indexed: 11/16/2022] Open
Abstract
Marine phytoplankton, comprising cyanobacteria, micro- and pico-algae are key to photosynthesis, oxygen production and carbon assimilation on Earth. The unicellular green picoalga Ostreococcus tauri holds a key position at the base of the green lineage of plants, which makes it an interesting model organism. O. tauri has adapted to survive in low levels of nitrogen and phosphorus in the open ocean and also during rapid changes in the levels of these nutrients in coastal waters. In this study, we have employed untargeted proteomic and lipidomic strategies to investigate the molecular responses of O. tauri to low-nitrogen and low-phosphorus environments. In the absence of external nitrogen, there was an elevation in the expression of ammonia and urea transporter proteins together with an accumulation of triglycerides. In phosphate-limiting conditions, the expression levels of phosphokinases and phosphate transporters were increased, indicating an attempt to maximise scavenging opportunities as opposed to energy conservation conditions. The production of betaine lipids was also elevated, highlighting a shift away from phospholipid metabolism. This finding was supported by the putative identification of betaine synthase in O. tauri. This work offers additional perspectives on the complex strategies that underpin the adaptive processes of the smallest known free-living eukaryote to alterations in environmental conditions.
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26
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Tang W, Cerdán-García E, Berthelot H, Polyviou D, Wang S, Baylay A, Whitby H, Planquette H, Mowlem M, Robidart J, Cassar N. New insights into the distributions of nitrogen fixation and diazotrophs revealed by high-resolution sensing and sampling methods. ISME JOURNAL 2020; 14:2514-2526. [PMID: 32581316 DOI: 10.1038/s41396-020-0703-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2019] [Revised: 06/08/2020] [Accepted: 06/11/2020] [Indexed: 01/26/2023]
Abstract
Nitrogen availability limits marine productivity across large ocean regions. Diazotrophs can supply new nitrogen to the marine environment via nitrogen (N2) fixation, relieving nitrogen limitation. The distributions of diazotrophs and N2 fixation have been hypothesized to be generally controlled by temperature, phosphorus, and iron availability in the global ocean. However, even in the North Atlantic where most research on diazotrophs and N2 fixation has taken place, environmental controls remain contentious. Here we measure diazotroph composition, abundance, and activity at high resolution using newly developed underway sampling and sensing techniques. We capture a diazotrophic community shift from Trichodesmium to UCYN-A between the oligotrophic, warm (25-29 °C) Sargasso Sea and relatively nutrient-enriched, cold (13-24 °C) subpolar and eastern American coastal waters. Meanwhile, N2 fixation rates measured in this study are among the highest ever recorded globally and show significant increase with phosphorus availability across the transition from the Gulf Stream into subpolar and coastal waters despite colder temperatures and higher nitrate concentrations. Transcriptional patterns in both Trichodesmium and UCYN-A indicate phosphorus stress in the subtropical gyre. Over this iron-replete transect spanning the western North Atlantic, our results suggest that temperature is the major factor controlling the diazotrophic community structure while phosphorous drives N2 fixation rates. Overall, the occurrence of record-high UCYN-A abundance and peak N2 fixation rates in the cold coastal region where nitrate concentrations are highest (~200 nM) challenges current paradigms on what drives the distribution of diazotrophs and N2 fixation.
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Affiliation(s)
- Weiyi Tang
- Division of Earth and Ocean Sciences, Nicholas School of the Environment, Duke University, Durham, NC, 27708, USA.,Department of Geosciences, Princeton University, Princeton, NJ, 08544, USA
| | - Elena Cerdán-García
- Department of Ocean and Earth Sciences, National Oceanography Centre, University of Southampton, European Way, SO14 3ZH, Southampton, UK
| | - Hugo Berthelot
- CNRS, Univ Brest, IRD, Ifremer, LEMAR, F-29280 Plouzané, France
| | - Despo Polyviou
- Department of Ocean and Earth Sciences, National Oceanography Centre, University of Southampton, European Way, SO14 3ZH, Southampton, UK
| | - Seaver Wang
- Division of Earth and Ocean Sciences, Nicholas School of the Environment, Duke University, Durham, NC, 27708, USA
| | - Alison Baylay
- Department of Ocean and Earth Sciences, National Oceanography Centre, University of Southampton, European Way, SO14 3ZH, Southampton, UK
| | - Hannah Whitby
- CNRS, Univ Brest, IRD, Ifremer, LEMAR, F-29280 Plouzané, France.,Department of Earth, Ocean and Ecological Sciences, School of Environmental Sciences, University of Liverpool, Liverpool, L69 3GP, UK
| | | | - Matthew Mowlem
- Ocean Technology and Engineering Group, National Oceanography Centre, European Way, SO14 3ZH, Southampton, UK
| | - Julie Robidart
- Ocean Technology and Engineering Group, National Oceanography Centre, European Way, SO14 3ZH, Southampton, UK.
| | - Nicolas Cassar
- Division of Earth and Ocean Sciences, Nicholas School of the Environment, Duke University, Durham, NC, 27708, USA. .,CNRS, Univ Brest, IRD, Ifremer, LEMAR, F-29280 Plouzané, France.
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27
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Zhang X, Ward BB, Sigman DM. Global Nitrogen Cycle: Critical Enzymes, Organisms, and Processes for Nitrogen Budgets and Dynamics. Chem Rev 2020; 120:5308-5351. [DOI: 10.1021/acs.chemrev.9b00613] [Citation(s) in RCA: 70] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Xinning Zhang
- Department of Geosciences, Princeton University, Princeton, New Jersey 08544, United States
- Princeton Environmental Institute, Princeton University, Princeton, New Jersey 08544, United States
| | - Bess B. Ward
- Department of Geosciences, Princeton University, Princeton, New Jersey 08544, United States
- Princeton Environmental Institute, Princeton University, Princeton, New Jersey 08544, United States
| | - Daniel M. Sigman
- Department of Geosciences, Princeton University, Princeton, New Jersey 08544, United States
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28
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Wang L, Xing P, Li H, Zhou L, Wu QL. Distinct Intra-lake Heterogeneity of Diazotrophs in a Deep Oligotrophic Mountain Lake. MICROBIAL ECOLOGY 2020; 79:840-852. [PMID: 31811330 DOI: 10.1007/s00248-019-01461-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2019] [Accepted: 11/07/2019] [Indexed: 06/10/2023]
Abstract
To date, little is known about the diazotrophs in freshwater ecosystems. In this study, we examined the diversity, abundance, and distribution of the diazotrophic community in the deep oligotrophic Lake Fuxian using high-throughput sequencing and quantitative polymerase chain reaction of nifH genes. Our results showed that the diazotrophs in Lake Fuxian were diverse and were distributed among Proteobacteria, Planctomycetes, Cyanobacteria, Verrucomicrobia, Bacteroidetes, Chloroflexi, and other unclassified environmental sequences. For the first time, it is found that Bacteroidetes and Planctomycetes harbor diazotrophs in freshwater ecosystems. The diazotrophic community compositions were significantly different between the littoral and pelagic zones in the surface layer, and they also changed dramatically along the vertical profile. High diazotrophic abundance and diversity were mostly observed in the surface littoral zone, and overall, a significant relationship between nifH gene richness and abundance was observed. The water turbidity, nitrite, and phosphorus were the most important factors explaining the spatial changes in diversity and abundances of this important functional group. The two most dominant operational taxonomic units belonging to Betaroproteobacteria and Planctomycetes demonstrated opposite distribution patterns in abundance that were driven by non-overlapping environmental factors. This study is by far the first to uncover the high diversity and intra-lake heterogeneity of diazotrophs in a freshwater lake and illuminate the controlling factors. It provides the probability of the co-occurrence of N2 fixation and N-loss in particles.
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Affiliation(s)
- Lina Wang
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, 73 East Beijing Road, Nanjing, 210008, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Peng Xing
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, 73 East Beijing Road, Nanjing, 210008, China.
| | - Huabing Li
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, 73 East Beijing Road, Nanjing, 210008, China
| | - Lijun Zhou
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, 73 East Beijing Road, Nanjing, 210008, China
| | - Qinglong L Wu
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, 73 East Beijing Road, Nanjing, 210008, China.
- Sino-Danish Center for Science and Education, University of Chinese Academy of Sciences, Beijing, China.
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29
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Zhang X, Lin S, Liu D. Transcriptomic and physiological responses of Skeletonema costatum to ATP utilization. Environ Microbiol 2020; 22:1861-1869. [PMID: 32077205 DOI: 10.1111/1462-2920.14944] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 02/13/2020] [Accepted: 02/14/2020] [Indexed: 11/26/2022]
Abstract
The capacity of phytoplankton to utilize dissolved organic phosphorus (DOP) plays an important role in their competition for resources when the availability of dissolved inorganic phosphorus (DIP) is low in the aquatic systems. Here, we explored the physiological and molecular responses of a globally distributed marine diatom, Skeletonema costatum, in utilizing adenosine-5'-triphosphate (ATP) based on incubation experiments under ATP, DIP-replete, and DIP-depleted conditions. The results show that ATP supports the growth of S. costatum as efficiently as DIP. The pathway of S. costatum involved in utilizing ATP is not related to alkaline phosphatase (AP), an important DOP hydrolase, although extracellular hydrolysis is involved. The transcriptome analysis revealed several transcripts related to the hydrolase activity (e.g. NAD+ diphosphatase), which were significantly upregulated in the ATP culture group, indicating their possible involvement in ATP hydrolysis. Meanwhile, ATP-grown S. costatum exhibited downregulation of the genes related to a series of metabolic activities (e.g. purine metabolism), apparently to adapt to ATP condition.
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Affiliation(s)
- Xiaohua Zhang
- Key Laboratory of Coastal Zone Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, 264003, China.,University of Chinese Academy of Sciences, Beijing, 100049, China.,Department of Gene Engineering, Binzhou Medical University, Yantai, 264003, China
| | - Senjie Lin
- Department of Marine Sciences, University of Connecticut, Groton, CT, 06340, USA
| | - Dongyan Liu
- State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai, 200241, China
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30
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Umair M, Sun N, Du H, Chen K, Tao H, Yuan J, Abbasi AM, Liu C. Differential stoichiometric responses of shrubs and grasses to increased precipitation in a degraded karst ecosystem in Southwestern China. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 700:134421. [PMID: 31693953 DOI: 10.1016/j.scitotenv.2019.134421] [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: 08/06/2019] [Revised: 09/10/2019] [Accepted: 09/11/2019] [Indexed: 06/10/2023]
Abstract
The elemental concentrations of both plants and soils are sensitive to variations in precipitation due to the limiting roles of water on soil processes and plant growth in karst ecosystems of Southwestern China; however, precipitation is predicted to increase in this region. Nevertheless, it is unclear how the elemental composition of soils and plants might respond to such increases in moisture. Particularly, how potassium (K) may behave as a key mediator in the regulation of the water potential of plants. For this study, the responses of the elemental composition of both soils and plants to the variable addition of water were investigated. Two grasses (Cymbopogon distans and Arundinella setosa) and two shrubs (Carissa spinarum and Bauhinia brachycarpa) were investigated under four levels of watering treatments 0%, +20%, +40%, and +60%, relative to the annual rainfall, respectively. Compared to the control (CK), the soil water content (SWC) increased to 3.75, 3.86, and 4.34 mg g-1 in T1, T2, and T3 groups, respectively (p < 0.05). Non-metal elements (C, H, N, S, and P, except for Si) in the soil were relatively stable with water addition; however, metal elements (Al, Na, Mg, Fe, and K, along with Si) increased significantly, whereas Zn and Ca decreased (p < 0.05). With water addition, leaf N and P remained unchanged in all four species, while K, Mg, and S decreased in both shrubs (higher C:K, N:K, and P:K). Increases in Fe, Si, and K were observed in both grasses (lower C:K, N:K, and P:K), which suggested that K played distinct roles for water regulation in shrubs and grasses. These findings implied that the elemental compositions of both soils and plants might be altered with increasing precipitation in the future, where different plant types may adopt distinct K-regulation strategies to cope with variable soil moisture.
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Affiliation(s)
- Muhammad Umair
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, China; Shanghai Urban Forest Research Station, State Forestry and Grassland Administration, China
| | - Ningxiao Sun
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, China; Shanghai Urban Forest Research Station, State Forestry and Grassland Administration, China; Key Laboratory of Urban Agriculture (South), Ministry of Agriculture, China
| | - Hongmei Du
- School of Design, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Kehao Chen
- School of Design, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Huimin Tao
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Jun Yuan
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Arshad Mehmood Abbasi
- Department of Environment Sciences, COMSATS University Islamabad, Abbottabad Campus, 22060, Pakistan
| | - Chunjiang Liu
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, China; Shanghai Urban Forest Research Station, State Forestry and Grassland Administration, China; Key Laboratory of Urban Agriculture (South), Ministry of Agriculture, China.
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31
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Fernández-Juárez V, Bennasar-Figueras A, Tovar-Sanchez A, Agawin NSR. The Role of Iron in the P-Acquisition Mechanisms of the Unicellular N 2-Fixing Cyanobacteria Halothece sp., Found in Association With the Mediterranean Seagrass Posidonia oceanica. Front Microbiol 2019; 10:1903. [PMID: 31507547 PMCID: PMC6713934 DOI: 10.3389/fmicb.2019.01903] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Accepted: 08/02/2019] [Indexed: 11/30/2022] Open
Abstract
Posidonia oceanica, an endemic seagrass of the Mediterranean Sea harbors a high diversity of N2-fixing prokaryotes. One of these is Halothece sp., a unicellular N2-fixing cyanobacteria detected through nifH analysis from the epiphytes of P. oceanica. The most related strain in culture is Halothece sp. PCC 7418 and this was used as the test organism in this study. In the Mediterranean Sea, phosphorus (P) and iron (Fe) can be the major limiting nutrients for N2 fixation. However, information about the mechanisms of P-acquisition and the role of metals (i.e., Fe) in these processes for N2-fixing bacteria is scarce. From our genomic analyses of the test organism and other phylogenetically related N2-fixing strains, Halothece sp. PCC 7418 is one of the strains with the greatest number of gene copies (eight copies) of alkaline phosphatases (APases). Our structural analysis of PhoD (alkaline phosphatase type D) and PhoU (phosphate acquisition regulator) of Halothece sp. PCC 7418 showed the connection among metals (Ca2+ and Fe3+), and the P-acquisition mechanisms. Here, we measured the rates of alkaline phosphatase activity (APA) through MUF-P hydrolysis under different combinations of concentrations of inorganic P (PO43−) and Fe in experiments under N2-fixing (low NO3− availability) and non-N2 fixing (high NO3− availability) conditions. Our results showed that APA rates were enhanced by the increase in Fe availability under low levels of PO43−, especially under N2-fixing conditions. Moreover, the increased PO43−-uptake was reflected in the increased of the P-cellular content of the cells under N2 fixation conditions. We also found a positive significant relationship between cellular P and cellular Fe content of the cells (r2 = 0.71, p < 0.05). Our results also indicated that Fe-uptake in Halothece sp. PCC 7418 was P and Fe-dependent. This study gives first insights of P-acquisition mechanisms in the N2-fixing cyanobacteria (Halothece sp.) found in P. oceanica and highlights the role of Fe in these processes.
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Affiliation(s)
- Víctor Fernández-Juárez
- Marine Ecology and Systematics (MarEs), Department of Biology, Universitat de les Illes Balears (UIB), Palma, Spain
| | - Antoni Bennasar-Figueras
- Grup de Recerca en Microbiologia, Departament de Biologia, Universitat de les Illes Balears (UIB), Palma, Spain
| | - Antonio Tovar-Sanchez
- Department of Ecology and Coastal Management, Andalusian Institute for Marine Sciences, ICMAN (CSIC), Cádiz, Spain
| | - Nona Sheila R Agawin
- Marine Ecology and Systematics (MarEs), Department of Biology, Universitat de les Illes Balears (UIB), Palma, Spain
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32
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Pereira N, Shilova IN, Zehr JP. Use of the high-affinity phosphate transporter gene, pstS, as an indicator for phosphorus stress in the marine diazotroph Crocosphaera watsonii (Chroococcales, Cyanobacteria). JOURNAL OF PHYCOLOGY 2019; 55:752-761. [PMID: 30929262 DOI: 10.1111/jpy.12863] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 03/18/2019] [Indexed: 06/09/2023]
Abstract
The marine diazotroph Crocosphaera watsonii provides fixed carbon (C) and nitrogen (N) to open-ocean regimes, where nutrient deficiency controls productivity. The growth of Crocosphaera can be limited by low phosphorus (P) concentrations in these oligotrophic environments. Biomarkers such as the high-affinity ABC transporter phosphate-binding gene, pstS, are commonly used to monitor when such organisms are under P stress; however, transcriptional regulation of these markers is often complex and not well-understood. In this study, we interrogated changes in pstS transcript levels in C. watsonii cells under P starvation, and in response to added dissolved inorganic phosphorus (DIP), dissolved organic phosphorus (DOP), and changing light levels. We observed elevated relative pstS transcript levels in C. watsonii WH8501 at DIP concentrations below 60 and above 20 nmol · L-1 . Transcript levels were suppressed by both inorganic and bioavailable organic phosphorus; however, the P stress response was more sensitive to DIP than DOP sources. Increasing light intensity resulted in increased relative pstS transcript abundances independently of low external P, and seemed to exacerbate the physiological effects of P stress. The variable response to different P compounds and rapid and transient influence of high light on pstS transcript abundances suggests that pstS is an indicator of internal P status in Crocosphaera.
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Affiliation(s)
- Nicole Pereira
- Ocean Sciences Department, University of California, 1156 High Street, Santa Cruz, California, 95064, USA
- Second Genome, 341 Allerton Avenue, South San Francisco, California, 94080, USA
| | - Irina N Shilova
- Ocean Sciences Department, University of California, 1156 High Street, Santa Cruz, California, 95064, USA
- Second Genome, 341 Allerton Avenue, South San Francisco, California, 94080, USA
| | - Jonathan P Zehr
- Ocean Sciences Department, University of California, 1156 High Street, Santa Cruz, California, 95064, USA
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Phosphate availability affects fixed nitrogen transfer from diazotrophs to their epibionts. ISME JOURNAL 2019; 13:2701-2713. [PMID: 31249392 PMCID: PMC6794295 DOI: 10.1038/s41396-019-0453-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 03/20/2019] [Accepted: 05/17/2019] [Indexed: 12/02/2022]
Abstract
Dinitrogen (N2) fixation is a major source of external nitrogen (N) to aquatic ecosystems and therefore exerts control over productivity. Studies have shown that N2 -fixers release freshly fixed N into the environment, but the causes for this N release are largely unclear. Here, we show that the availability of phosphate can directly affect the transfer of freshly fixed N to epibionts in filamentous, diazotrophic cyanobacteria. Stable-isotope incubations coupled to single-cell analyses showed that <1% and ~15% of freshly fixed N was transferred to epibionts of Aphanizomenon and Nodularia, respectively, at phosphate scarcity during a summer bloom in the Baltic Sea. When phosphate was added, the transfer of freshly fixed N to epibionts dropped to about half for Nodularia, whereas the release from Aphanizomenon increased slightly. At the same time, the growth rate of Nodularia roughly doubled, indicating that less freshly fixed N was released and was used for biomass production instead. Phosphate scarcity and the resulting release of freshly fixed N could explain the heavy colonization of Nodularia filaments by microorganisms during summer blooms. As such, the availability of phosphate may directly affect the partitioning of fixed N2 in colonies of diazotrophic cyanobacteria and may impact the interactions with their microbiome.
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Qu P, Fu FX, Kling JD, Huh M, Wang X, Hutchins DA. Distinct Responses of the Nitrogen-Fixing Marine Cyanobacterium Trichodesmium to a Thermally Variable Environment as a Function of Phosphorus Availability. Front Microbiol 2019; 10:1282. [PMID: 31244804 PMCID: PMC6579863 DOI: 10.3389/fmicb.2019.01282] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 05/23/2019] [Indexed: 12/05/2022] Open
Abstract
Surface temperature in the ocean is projected to be elevated and more variable in the future, which will interact with other environmental changes like reduced nutrient supplies. To explore these multiple stressor relationships, we tested the influence of thermal variation on the key marine diazotrophic cyanobacterium Trichodesmium erythraeum GBRTRLI101 as a function of the limiting nutrient phosphorus (P). Two constant temperature treatments represented current winter (22°C) and summer (30°C) mean values. Three variable temperature treatments fluctuated around the constant control values: Mean 22°C, either ± 2°C or ± 4°C; and mean 30°C ± 2°C. Each thermal treatment was grown under both P-replete (10 μmol/L) and P-limiting conditions (0.2 μmol/L). Effects of thermal variability on Trichodesmium were mainly found in the two winter variable temperature treatments (22°C ± 2°C or ± 4°C). P availability affected growth and physiology in all treatments and had significant interactions with temperature. P-replete cultures had higher growth and nitrogen and carbon fixation rates in the 22°C constant control, than in the corresponding variable treatments. However, physiological rates were not different in the P-replete constant and variable treatments at 30°C. In contrast, in P-limited cultures an advantage of constant temperature over variable temperature was not apparent. Phosphorus use efficiencies (PUE, mol N or C fixed h-1 mol cellular P-1) for nitrogen and carbon fixation were significantly elevated under P-limited conditions, and increased with temperature from 22 to 30°C, implying a potential advantage in a future warmer, P-limited environment. Taken together, these results imply that future increasing temperature and greater thermal variability could have significant feedback interactions with the projected intensification of P-limitation of marine N2-fixing cyanobacteria.
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Affiliation(s)
- Pingping Qu
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, United States
| | - Fei-Xue Fu
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, United States
| | - Joshua D. Kling
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, United States
| | - Megan Huh
- Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
| | - Xinwei Wang
- School of Life Sciences, Xiamen University, Xiamen, China
| | - David A. Hutchins
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, United States
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Luo YW, Shi D, Kranz SA, Hopkinson BM, Hong H, Shen R, Zhang F. Reduced nitrogenase efficiency dominates response of the globally important nitrogen fixer Trichodesmium to ocean acidification. Nat Commun 2019; 10:1521. [PMID: 30944323 PMCID: PMC6447586 DOI: 10.1038/s41467-019-09554-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2018] [Accepted: 03/19/2019] [Indexed: 12/25/2022] Open
Abstract
The response of the prominent marine dinitrogen (N2)-fixing cyanobacteria Trichodesmium to ocean acidification (OA) is critical to understanding future oceanic biogeochemical cycles. Recent studies have reported conflicting findings on the effect of OA on growth and N2 fixation of Trichodesmium. Here, we quantitatively analyzed experimental data on how Trichodesmium reallocated intracellular iron and energy among key cellular processes in response to OA, and integrated the findings to construct an optimality-based cellular model. The model results indicate that Trichodesmium growth rate decreases under OA primarily due to reduced nitrogenase efficiency. The downregulation of the carbon dioxide (CO2)-concentrating mechanism under OA has little impact on Trichodesmium, and the energy demand of anti-stress responses to OA has a moderate negative effect. We predict that if anthropogenic CO2 emissions continue to rise, OA could reduce global N2 fixation potential of Trichodesmium by 27% in this century, with the largest decrease in iron-limiting regions.
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Affiliation(s)
- Ya-Wei Luo
- State Key Laboratory of Marine Environmental Science and College of Ocean and Earth Sciences, Xiamen University, 361102, Xiamen, Fujian, China.
| | - Dalin Shi
- State Key Laboratory of Marine Environmental Science and College of the Environment and Ecology, Xiamen University, 361102, Xiamen, Fujian, China.
| | - Sven A Kranz
- Department of Earth, Ocean and Atmospheric Science, Florida State University, Tallahassee, FL, 32306, USA
| | - Brian M Hopkinson
- Department of Marine Sciences, University of Georgia, Athens, GA, 30602, USA
| | - Haizheng Hong
- State Key Laboratory of Marine Environmental Science and College of the Environment and Ecology, Xiamen University, 361102, Xiamen, Fujian, China
| | - Rong Shen
- State Key Laboratory of Marine Environmental Science and College of the Environment and Ecology, Xiamen University, 361102, Xiamen, Fujian, China
| | - Futing Zhang
- State Key Laboratory of Marine Environmental Science and College of the Environment and Ecology, Xiamen University, 361102, Xiamen, Fujian, China
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Frischkorn KR, Haley ST, Dyhrman ST. Transcriptional and Proteomic Choreography Under Phosphorus Deficiency and Re-supply in the N 2 Fixing Cyanobacterium Trichodesmium erythraeum. Front Microbiol 2019; 10:330. [PMID: 30891009 PMCID: PMC6411698 DOI: 10.3389/fmicb.2019.00330] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Accepted: 02/08/2019] [Indexed: 01/27/2023] Open
Abstract
The N2 fixing cyanobacterium Trichodesmium is a critically important organism in oligotrophic marine ecosystems, supplying “new” nitrogen (N) to the otherwise N-poor tropical and subtropical regions where it occurs. Low concentrations of phosphorus (P) in these regions can constrain Trichodesmium distribution and N2 fixation rates. Physiological characterization of a single species in a mixed community can be challenging, and ‘omic approaches are increasingly important tools for tracking nutritional physiology in a taxon-specific manner. As such, studies examining the dynamics of gene and protein markers of physiology (e.g., nutrient stress) are critical for the application and interpretation of such ‘omic data in situ. Here we leveraged combined transcriptomics, proteomics, and enzyme activity assays to track the physiological response of Trichodesmium erythraeum IMS101 to P deficiency and subsequent P re-supply over 72 h of sampling. P deficiency resulted in differential gene expression, protein abundance, and enzyme activity that highlighted a synchronous shift in P physiology with increases in the transcripts and corresponding proteins for hydrolyzing organic phosphorus, taking up phosphate with higher affinity, and modulating intracellular P demand. After P deficiency was alleviated, gene expression of these biomarkers was reduced to replete levels within 4 h of P amendment. A number of these gene biomarkers were adjacent to putative pho boxes and their expression patterns were similar to a sphR response regulator. Protein products of the P deficiency biomarkers were slow to decline, with 84% of the original P deficient protein set still significantly differentially expressed after 72 h. Alkaline phosphatase activity tracked with proteins for this enzyme. With the rapid turnover time of transcripts, they appear to be good biomarkers of a P stress phenotype, whereas proteins, with a slower turnover time, may better reflect cellular activities. These results highlight the importance of validating and pairing transcriptome and proteome data that can be applied to physiological studies of key species in situ.
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Affiliation(s)
- Kyle R Frischkorn
- Department of Earth and Environmental Sciences, Columbia University, New York, NY, United States.,Lamont-Doherty Earth Observatory, Palisades, NY, United States
| | - Sheean T Haley
- Lamont-Doherty Earth Observatory, Palisades, NY, United States
| | - Sonya T Dyhrman
- Department of Earth and Environmental Sciences, Columbia University, New York, NY, United States.,Lamont-Doherty Earth Observatory, Palisades, NY, United States
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37
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Convergent estimates of marine nitrogen fixation. Nature 2019; 566:205-211. [DOI: 10.1038/s41586-019-0911-2] [Citation(s) in RCA: 123] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2018] [Accepted: 12/17/2018] [Indexed: 11/08/2022]
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Unique Patterns and Biogeochemical Relevance of Two-Component Sensing in Marine Bacteria. mSystems 2019; 4:mSystems00317-18. [PMID: 30746496 PMCID: PMC6365647 DOI: 10.1128/msystems.00317-18] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Accepted: 01/11/2019] [Indexed: 12/20/2022] Open
Abstract
Marine microbes must manage variation in their chemical, physical, and biological surroundings. Because they directly link bacterial physiology to environmental changes, TCS systems are crucial to the bacterial cell. This study surveyed TCS systems in a large number of marine bacteria and identified key phylogenetic and lifestyle patterns in environmental sensing. We found evidence that, in comparison with bacteria as a whole, marine organisms have irregular TCS system constructs which might represent an adaptation specific to the marine environment. Additionally, we demonstrate the biogeochemical relevance of TCS systems by correlating the presence of the PMT9312_0717 response regulator protein to phosphate concentrations in the South Pacific. We highlight that despite their potential ecological and biogeochemical relevance, TCS systems have been understudied in the marine ecosystem. This report expands our understanding of the breadth of bacterial TCS systems and how marine bacteria have adapted to survive in their unique environment. Two-component sensory (TCS) systems link microbial physiology to the environment and thus may play key roles in biogeochemical cycles. In this study, we surveyed the TCS systems of 328 diverse marine bacterial species. We identified lifestyle traits such as copiotrophy and diazotrophy that are associated with larger numbers of TCS system genes within the genome. We compared marine bacterial species with 1,152 reference bacterial species from a variety of habitats and found evidence of extra response regulators in marine genomes. Examining the location of TCS genes along the circular bacterial genome, we also found that marine bacteria have a large number of “orphan” genes, as well as many hybrid histidine kinases. The prevalence of “extra” response regulators, orphan genes, and hybrid TCS systems suggests that marine bacteria break with traditional understanding of how TCS systems operate. These trends suggest prevalent regulatory networking, which may allow coordinated physiological responses to multiple environmental signals and may represent a specific adaptation to the marine environment. We examine phylogenetic and lifestyle traits that influence the number and structure of two-component systems in the genome, finding, for example, that a lack of two-component systems is a hallmark of oligotrophy. Finally, in an effort to demonstrate the importance of TCS systems to marine biogeochemistry, we examined the distribution of Prochlorococcus/Synechococcus response regulator PMT9312_0717 in metaproteomes of the tropical South Pacific. We found that this protein’s abundance is related to phosphate concentrations, consistent with a putative role in phosphate regulation. IMPORTANCE Marine microbes must manage variation in their chemical, physical, and biological surroundings. Because they directly link bacterial physiology to environmental changes, TCS systems are crucial to the bacterial cell. This study surveyed TCS systems in a large number of marine bacteria and identified key phylogenetic and lifestyle patterns in environmental sensing. We found evidence that, in comparison with bacteria as a whole, marine organisms have irregular TCS system constructs which might represent an adaptation specific to the marine environment. Additionally, we demonstrate the biogeochemical relevance of TCS systems by correlating the presence of the PMT9312_0717 response regulator protein to phosphate concentrations in the South Pacific. We highlight that despite their potential ecological and biogeochemical relevance, TCS systems have been understudied in the marine ecosystem. This report expands our understanding of the breadth of bacterial TCS systems and how marine bacteria have adapted to survive in their unique environment.
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Schoffelen NJ, Mohr W, Ferdelman TG, Littmann S, Duerschlag J, Zubkov MV, Ploug H, Kuypers MMM. Single-cell imaging of phosphorus uptake shows that key harmful algae rely on different phosphorus sources for growth. Sci Rep 2018; 8:17182. [PMID: 30464246 PMCID: PMC6249326 DOI: 10.1038/s41598-018-35310-w] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Accepted: 11/02/2018] [Indexed: 12/04/2022] Open
Abstract
Single-cell measurements of biochemical processes have advanced our understanding of cellular physiology in individual microbes and microbial populations. Due to methodological limitations, little is known about single-cell phosphorus (P) uptake and its importance for microbial growth within mixed field populations. Here, we developed a nanometer-scale secondary ion mass spectrometry (nanoSIMS)-based approach to quantify single-cell P uptake in combination with cellular CO2 and N2 fixation. Applying this approach during a harmful algal bloom (HAB), we found that the toxin-producer Nodularia almost exclusively used phosphate for growth at very low phosphate concentrations in the Baltic Sea. In contrast, the non-toxic Aphanizomenon acquired only 15% of its cellular P-demand from phosphate and ~85% from organic P. When phosphate concentrations were raised, Nodularia thrived indicating that this toxin-producer directly benefits from phosphate inputs. The phosphate availability in the Baltic Sea is projected to rise and therefore might foster more frequent and intense Nodularia blooms with a concomitant rise in the overall toxicity of HABs in the Baltic Sea. With a projected increase in HABs worldwide, the capability to use organic P may be a critical factor that not only determines the microbial community structure, but the overall harmfulness and associated costs of algal blooms.
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Affiliation(s)
- Niels J Schoffelen
- Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, Celsiusstraße 1, 28359, Bremen, Germany
| | - Wiebke Mohr
- Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, Celsiusstraße 1, 28359, Bremen, Germany.
| | - Timothy G Ferdelman
- Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, Celsiusstraße 1, 28359, Bremen, Germany
| | - Sten Littmann
- Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, Celsiusstraße 1, 28359, Bremen, Germany
| | - Julia Duerschlag
- Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, Celsiusstraße 1, 28359, Bremen, Germany
| | - Mikhail V Zubkov
- Ocean Biogeochemistry and Ecosystems, National Oceanography Centre Southampton, European Way, Southampton, SO14 3ZH, United Kingdom.,Scottish Association for Marine Science, Oban, Argyll PA37 1QA, Scotland, United Kingdom
| | - Helle Ploug
- Department of Marine Sciences, University of Gothenburg, Carl Skottsbergs Gata 22B, 41319, Gothenburg, Sweden
| | - Marcel M M Kuypers
- Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, Celsiusstraße 1, 28359, Bremen, Germany
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Outer Membrane Iron Uptake Pathways in the Model Cyanobacterium Synechocystis sp. Strain PCC 6803. Appl Environ Microbiol 2018; 84:AEM.01512-18. [PMID: 30076192 DOI: 10.1128/aem.01512-18] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 07/21/2018] [Indexed: 02/01/2023] Open
Abstract
Cyanobacteria are foundational drivers of global nutrient cycling, with high intracellular iron (Fe) requirements. Fe is found at extremely low concentrations in aquatic systems, however, and the ways in which cyanobacteria take up Fe are largely unknown, especially the initial step in Fe transport across the outer membrane. Here, we identified one TonB protein and four TonB-dependent transporters (TBDTs) of the energy-requiring Fe acquisition system and six porins of the passive diffusion Fe uptake system in the model cyanobacterium Synechocystis sp. strain PCC 6803. The results experimentally demonstrated that TBDTs not only participated in organic ferri-siderophore uptake but also in inorganic free Fe (Fe') acquisition. 55Fe uptake rate measurements showed that a TBDT quadruple mutant acquired Fe at a lower rate than the wild type and lost nearly all ability to take up ferri-siderophores, indicating that TBDTs are critical for siderophore uptake. However, the mutant retained the ability to take up Fe' at 42% of the wild-type Fe' uptake rate, suggesting additional pathways of Fe' acquisition besides TBDTs, likely by porins. Mutations in four of the six porin-encoding genes produced a low-Fe-sensitive phenotype, while a mutation in all six genes was lethal to cell survival. These diverse outer membrane Fe uptake pathways reflect cyanobacterial evolution and adaptation under a range of Fe regimes across aquatic systems.IMPORTANCE Cyanobacteria are globally important primary producers and contribute about 25% of global CO2 fixation. Low Fe bioavailability in surface waters is thought to limit the primary productivity in as much as 40% of the global ocean. The Fe acquisition strategies that cyanobacteria have evolved to overcome Fe deficiency remain poorly characterized. We experimentally characterized the key players and the cooperative work mode of two Fe uptake pathways, including an active uptake pathway and a passive diffusion pathway in the model cyanobacterium Synechocystis sp. PCC 6803. Our finding proved that cyanobacteria use ferri-siderophore transporters to take up Fe', and they shed light on the adaptive mechanisms of cyanobacteria to cope with widespread Fe deficiency across aquatic environments.
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Fraser MW, Gleeson DB, Grierson PF, Laverock B, Kendrick GA. Metagenomic Evidence of Microbial Community Responsiveness to Phosphorus and Salinity Gradients in Seagrass Sediments. Front Microbiol 2018; 9:1703. [PMID: 30105009 PMCID: PMC6077243 DOI: 10.3389/fmicb.2018.01703] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 07/09/2018] [Indexed: 12/17/2022] Open
Abstract
Sediment microorganisms can have profound influence on productivity and functioning of marine ecosystems through their critical roles in regulating biogeochemical processes. However, the identity of sediment microorganisms that mediate organic matter turnover and nutrient cycling in seagrass sediments is only poorly understood. Here, we used metagenomic sequencing to investigate shifts in the structure and functioning of the microbial community of seagrass sediments across a salinity and phosphorus (P) availability gradient in Shark Bay, WA, Australia. This iconic ecosystem is oligotrophic and hypersaline with abundant seagrass meadows that directly contribute Shark Bay's status as a World Heritage Site. We show that sediment phosphonate metabolism genes as well as enzyme activities increase in hypersaline conditions with lower soluble reactive phosphate in the water column. Given that sediment organic P content is also highest where P concentrations in the water column are low, we suggest that microbial processing of organic P can contribute to the P requirements of seagrasses at particularly oligotrophic sites. Seagrass meadows are often highly productive in oligotrophic waters, and our findings suggest that an increase in the functional capacity of microbial communities in seagrass sediments to break down organic P may contribute to the high productivity of seagrass meadows under oligotrophic conditions. When compared to soil and sediment metagenomes from other aquatic and terrestrial ecosystems, we also show microbial communities in seagrass sediments have a disproportionately high abundance of putative phosphorus and sulfur metabolism genes, which may have played an important evolutionary role in allowing these angiosperms to recolonize the marine environment and prosper under oligotrophic conditions.
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Affiliation(s)
- Matthew W. Fraser
- School of Biological Sciences, The University of Western Australia, Crawley, WA, Australia
- Oceans Institute, The University of Western Australia, Crawley, WA, Australia
| | - Deirdre B. Gleeson
- UWA School of Agriculture and Environment, The University of Western Australia, Crawley, WA, Australia
| | - Pauline F. Grierson
- School of Biological Sciences, The University of Western Australia, Crawley, WA, Australia
| | - Bonnie Laverock
- School of Biological Sciences, The University of Western Australia, Crawley, WA, Australia
- Oceans Institute, The University of Western Australia, Crawley, WA, Australia
- School of Science, Auckland University of Technology, Auckland, New Zealand
| | - Gary A. Kendrick
- School of Biological Sciences, The University of Western Australia, Crawley, WA, Australia
- Oceans Institute, The University of Western Australia, Crawley, WA, Australia
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Liu J, Zhou L, Ke Z, Li G, Shi R, Tan Y. Beneficial effects of aluminum enrichment on nitrogen-fixing cyanobacteria in the South China Sea. MARINE POLLUTION BULLETIN 2018; 129:142-150. [PMID: 29680532 DOI: 10.1016/j.marpolbul.2018.02.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Revised: 01/25/2018] [Accepted: 02/05/2018] [Indexed: 06/08/2023]
Abstract
Few studies focus on the effects of aluminum (Al) on marine nitrogen-fixing cyanobacteria, which play important roles in the ocean nitrogen cycling. To examine the effects of Al on the nitrogen-fixing cyanobacteria, bioassay experiments in the oligotrophic South China Sea (SCS) and culture of Crocosphaera watsonii in the laboratory were conducted. Field data showed that 200 nM Al stimulated the growth and the nitrogenase gene expression of Trichodesmium and unicellular diazotrophic cyanobacterium group A, and the nitrogen fixation rates of the whole community. Laboratory experiments demonstrated that Al stimulated the growth and nitrogen fixation of C. watsonii under phosphorus limited conditions. Both field and laboratory results indicated that Al could stimulate the growth of diazotrophs and nitrogen fixation in oligotrophic oceans such as the SCS, which is likely related to the utilization of phosphorus, implying that Al plays an important role in the ocean nitrogen and carbon cycles by influencing nitrogen fixation.
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Affiliation(s)
- Jiaxing Liu
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, No. 164, West Xingang Road, Guangzhou 510301, China; Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Linbin Zhou
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, No. 164, West Xingang Road, Guangzhou 510301, China; Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhixin Ke
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, No. 164, West Xingang Road, Guangzhou 510301, China; Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China
| | - Gang Li
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, No. 164, West Xingang Road, Guangzhou 510301, China; Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China
| | - Rongjun Shi
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, No. 164, West Xingang Road, Guangzhou 510301, China; Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yehui Tan
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, No. 164, West Xingang Road, Guangzhou 510301, China; Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China.
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Ogburn ZL, Vogt F. Modeling Microalgal Biosediment Formation Based on Attenuated Total Reflection Fourier Transform Infrared (ATR FT-IR) Monitoring. APPLIED SPECTROSCOPY 2018; 72:366-377. [PMID: 28777003 DOI: 10.1177/0003702817728070] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
With increasing amounts of anthropogenic pollutants being released into ecosystems, it becomes ever more important to understand their fate and interactions with living organisms. Microalgae play an important ecological role as they are ubiquitous in marine environments and sequester inorganic pollutants which they transform into organic biomass. Of particular interest in this study is their role as a sink for atmospheric CO2, a greenhouse gas, and nitrate, one cause of harmful algal blooms. Novel chemometric hard-modeling methodologies have been developed for interpreting phytoplankton's chemical and physiological adaptations to changes in their growing environment. These methodologies will facilitate investigations of environmental impacts of anthropogenic pollutants on chemical and physiological properties of marine microalgae (here: Nannochloropsis oculata). It has been demonstrated that attenuated total reflection Fourier transform infrared (ATR FT-IR) spectroscopy can gain insights into both and this study only focuses on the latter. From time-series of spectra, the rate of microalgal biomass settling on top of a horizontal ATR element is derived which reflects several of phytoplankton's physiological parameters such as growth rate, cell concentrations, cell size, and buoyancy. In order to assess environmental impacts on such parameters, microalgae cultures were grown under 25 different chemical scenarios covering 200-600 ppm atmospheric CO2 and 0.35-0.75 mM dissolved NO3-. After recording time-series of ATR FT-IR spectra, a multivariate curve resolution-alternating least squares (MCR-ALS) algorithm extracted spectroscopic and time profiles from each data set. From the time profiles, it was found that in the considered concentration ranges only NO3- has an impact on the cells' physiological properties. In particular, the cultures' growth rate has been influenced by the ambient chemical conditions. Thus, the presented spectroscopic + chemometric methodology enables investigating the link between chemical conditions in a marine ecosystem and their consequences for phytoplankton living in it.
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Affiliation(s)
- Zachary L Ogburn
- Department of Chemistry, University of Tennessee, Knoxville, TN, USA
| | - Frank Vogt
- Department of Chemistry, University of Tennessee, Knoxville, TN, USA
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Transcriptional patterns identify resource controls on the diazotroph Trichodesmium in the Atlantic and Pacific oceans. ISME JOURNAL 2018; 12:1486-1495. [PMID: 29491494 DOI: 10.1038/s41396-018-0087-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2017] [Revised: 12/31/2017] [Accepted: 01/10/2018] [Indexed: 12/21/2022]
Abstract
The N2-fixing cyanobacterium Trichodesmium is intensely studied because of the control this organism exerts over the cycling of carbon and nitrogen in the low nutrient ocean gyres. Although iron (Fe) and phosphorus (P) bioavailability are thought to be major drivers of Trichodesmium distributions and activities, identifying resource controls on Trichodesmium is challenging, as Fe and P are often organically complexed and their bioavailability to a single species in a mixed community is difficult to constrain. Further, Fe and P geochemistries are linked through the activities of metalloenzymes, such as the alkaline phosphatases (APs) PhoX and PhoA, which are used by microbes to access dissolved organic P (DOP). Here we identified significant correlations between Trichodesmium-specific transcriptional patterns in the North Atlantic (NASG) and North Pacific Subtropical Gyres (NPSG) and patterns in Fe and P biogeochemistry, with the relative enrichment of Fe stress markers in the NPSG, and P stress markers in the NASG. We also observed the differential enrichment of Fe-requiring PhoX transcripts in the NASG and Fe-insensitive PhoA transcripts in the NPSG, suggesting that metalloenzyme switching may be used to mitigate Fe limitation of DOP metabolism in Trichodesmium. This trait may underpin Trichodesmium success across disparate ecosystems.
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Iron and phosphorus deprivation induce sociality in the marine bloom-forming cyanobacterium Trichodesmium. ISME JOURNAL 2018; 12:1682-1693. [PMID: 29463890 DOI: 10.1038/s41396-018-0073-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 01/23/2018] [Accepted: 01/25/2018] [Indexed: 11/09/2022]
Abstract
Trichodesmium spp. are diazotrophic cyanobacteria that exist as single filaments (trichomes) and as macroscopic colonies of varying shapes formed by aggregating trichomes. The causes and dynamics of colony formation and disassociation are not yet elucidated. we demonstrate that limited availability of dissolved phosphorus (P) or iron (Fe) stimulated trichome mobility and induced colony formation in Trichodesmium erythraeum IMS101 cultures. The specific nutrient limitation differentially affected the rate of colony formation and morphology of the colonies. Fe starvation promoted rapid colony formation (10-48 h from depletion) while 5-7 days were required for colonies to form in P-depleted cultures. Video analyses confirmed that the probability of trichomes to cluster increased from 12 to 35% when transferred from nutrient replete to Fe-depleted conditions. Moreover, the probability for Fe-depleted aggregates to remain colonial increased to 50% from only 10% in nutrient replete cultures. These colonies were also characterized by stronger attachment forces between the trichomes. Enrichment of nutrient-depleted cultures with the limited nutrient-stimulated colony dissociation into single trichomes. We postulate that limited P and Fe availability enhance colony formation of Trichodesmium and primarily control the abundance and distribution of its different morphologies in the nutrient-limited surface ocean.
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Cassar N, Tang W, Gabathuler H, Huang K. Method for High Frequency Underway N 2 Fixation Measurements: Flow-Through Incubation Acetylene Reduction Assays by Cavity Ring Down Laser Absorption Spectroscopy (FARACAS). Anal Chem 2018; 90:2839-2851. [PMID: 29338196 DOI: 10.1021/acs.analchem.7b04977] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Because of the difficulty in resolving the large variability of N2 fixation with current methods which rely on discrete sampling, the development of new methods for high-resolution measurements is highly desirable. We present a new method for high-frequency measurements of aquatic N2 fixation by continuous flow-through incubations and spectral monitoring of the acetylene (C2H2, a substrate analog for N2) reduction to ethylene (C2H4). In this method, named Flow-through Incubation Acetylene Reduction Assays by Cavity Ring-Down Laser Absorption Spectroscopy (FARACAS), dissolved C2H2 is continuously admixed with seawater upstream of a continuous-flow stirred-tank reactor (CFSR) in which C2H2 reduction takes place. Downstream of the flow-through incubator, the C2H4 gas is stripped using a bubble column contactor and circulated with a diaphragm pump into a wavelength-scanned cavity ring down laser absorption spectrometer (CRDS). Our method provides high-resolution and precise mapping of aquatic N2 fixation, its diel cycle, and its response to environmental gradients, and can be adapted to measure other biological processes. The short-duration of the flow-through incubations without preconcentration of cells minimizes potential artifacts such as bottle containment effects while providing near real-time estimates for adaptive sampling. We expect that our new method will improve the characterization of the biogeography and kinetics of aquatic N2 fixation rates.
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Affiliation(s)
- Nicolas Cassar
- Division of Earth and Ocean Sciences, Nicholas School of the Environment, Duke University , Durham, North Carolina 27708, United States.,Laboratoire des Sciences de l'Environnement Marin (LEMAR), UMR 6539 UBO/CNRS/IRD/IFREMER, Institut Universitaire Européen de la Mer (IUEM) , Brest, France
| | - Weiyi Tang
- Division of Earth and Ocean Sciences, Nicholas School of the Environment, Duke University , Durham, North Carolina 27708, United States
| | | | - Kuan Huang
- Division of Earth and Ocean Sciences, Nicholas School of the Environment, Duke University , Durham, North Carolina 27708, United States
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Polyviou D, Baylay AJ, Hitchcock A, Robidart J, Moore CM, Bibby TS. Desert Dust as a Source of Iron to the Globally Important Diazotroph Trichodesmium. Front Microbiol 2018; 8:2683. [PMID: 29387046 PMCID: PMC5776111 DOI: 10.3389/fmicb.2017.02683] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Accepted: 12/22/2017] [Indexed: 12/22/2022] Open
Abstract
The marine cyanobacterium Trichodesmium sp. accounts for approximately half of the annual ‘new’ nitrogen introduced to the global ocean but its biogeography and activity is often limited by the availability of iron (Fe). A major source of Fe to the open ocean is Aeolian dust deposition in which Fe is largely comprised of particles with reduced bioavailability over soluble forms of Fe. We report that Trichodesmium erythraeum IMS101 has improved growth rate and photosynthetic physiology and down-regulates Fe-stress biomarker genes when cells are grown in the direct vicinity of, rather than physically separated from, Saharan dust particles as the sole source of Fe. These findings suggest that availability of non-soluble forms of dust-associated Fe may depend on cell contact. Transcriptomic analysis further reveals unique profiles of gene expression in all tested conditions, implying that Trichodesmium has distinct molecular signatures related to acquisition of Fe from different sources. Trichodesmium thus appears to be capable of employing specific mechanisms to access Fe from complex sources in oceanic systems, helping to explain its role as a key microbe in global biogeochemical cycles.
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Affiliation(s)
- Despo Polyviou
- Ocean and Earth Science, University of Southampton, Waterfront Campus, Southampton, United Kingdom
| | - Alison J Baylay
- Ocean and Earth Science, University of Southampton, Waterfront Campus, Southampton, United Kingdom
| | - Andrew Hitchcock
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Sheffield, United Kingdom
| | - Julie Robidart
- Ocean Technology and Engineering Group, National Oceanography Centre, Southampton, United Kingdom
| | - C M Moore
- Ocean and Earth Science, University of Southampton, Waterfront Campus, Southampton, United Kingdom
| | - Thomas S Bibby
- Ocean and Earth Science, University of Southampton, Waterfront Campus, Southampton, United Kingdom
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Hasan MF, Vogt F. Quantitative modeling of microalgae based sequestration of atmospheric CO 2. Analyst 2018; 143:1042-1045. [DOI: 10.1039/c7an01781b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A novel modeling method is presented to quantify the sequestration of atmospheric CO2 by marine microalgae.
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Affiliation(s)
| | - Frank Vogt
- Department of Chemistry
- University of Tennessee
- Knoxville
- USA
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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 2017; 84:AEM.02026-17. [PMID: 29054872 DOI: 10.1128/aem.02026-17] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Accepted: 10/15/2017] [Indexed: 11/20/2022] Open
Abstract
Trichodesmium is a globally distributed cyanobacterium whose nitrogen-fixing capability fuels primary production in warm oligotrophic oceans. Like many photoautotrophs, Trichodesmium serves as a host to various other microorganisms, yet little is known about how this associated community modulates fluxes of environmentally relevant chemical species into and out of the supraorganismal structure. Here, we utilized metatranscriptomics to examine gene expression activities of microbial communities associated with Trichodesmium erythraeum (strain IMS101) using laboratory-maintained enrichment cultures that have previously been shown to harbor microbial communities similar to those of natural populations. In enrichments maintained under two distinct CO2 concentrations for ∼8 years, the community transcriptional profiles were found to be specific to the treatment, demonstrating a restructuring of overall gene expression had occurred. Some of this restructuring involved significant increases in community respiration-related transcripts under elevated CO2, potentially facilitating the corresponding measured increases in host nitrogen fixation rates. Particularly of note, in both treatments, community transcripts involved in the reduction of nitrate, nitrite, and nitrous oxide were detected, suggesting the associated organisms may play a role in colony-level nitrogen cycling. Lastly, a taxon-specific analysis revealed distinct ecological niches of consistently cooccurring major taxa that may enable, or even encourage, the stable cohabitation of a diverse community within Trichodesmium consortia.IMPORTANCETrichodesmium is a genus of globally distributed, nitrogen-fixing marine cyanobacteria. As a source of new nitrogen in otherwise nitrogen-deficient systems, these organisms help fuel carbon fixation carried out by other more abundant photoautotrophs and thereby have significant roles in global nitrogen and carbon cycling. Members of the Trichodesmium genus tend to form large macroscopic colonies that appear to perpetually host an association of diverse interacting microbes distinct from the surrounding seawater, potentially making the entire assemblage a unique miniature ecosystem. Since its first successful cultivation in the early 1990s, there have been questions about the potential interdependencies between Trichodesmium and its associated microbial community and whether the host's seemingly enigmatic nitrogen fixation schema somehow involved or benefited from its epibionts. Here, we revisit these old questions with new technology and investigate gene expression activities of microbial communities living in association with Trichodesmium.
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Nitrogen fixation in two coastal upwelling regions of the Taiwan Strait. Sci Rep 2017; 7:17601. [PMID: 29242536 PMCID: PMC5730613 DOI: 10.1038/s41598-017-18006-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Accepted: 12/05/2017] [Indexed: 11/08/2022] Open
Abstract
Recent studies have demonstrated that dinitrogen fixation can be important in nutrient-rich coastal upwelling regions. During a cruise to the Taiwan Strait in summer 2015, we found that the nitrogen fixation rate in surface waters ranged from below detection limits to 7.51 nmol N L−1 d−1. Higher rates accompanied by low N:P ratios (1–10.4:1) associated with low temperatures occurred in the surface water where the Pingtan and the Dongshan upwelling regions met (the NE area). In contrast, insignificant rates were observed in the southwest area of the Dongshan upwelling region (the SW area) with sufficient N and deficient P, and therefore high N:P ratios (e.g., >43 at station C2) due largely to the influence of the Pearl River plume. Diatom-associated symbionts (het-1; 104–106 copies L−1) that are efficient in organic matter export were found to dominate the other diazotrophic groups that were surveyed, which may represent a direct relationship between new nitrogen input and export in the upwelling regions. Our results suggest a hydrographical influence on the diazotroph community and N2 fixation in coastal upwelling regions.
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