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Graf J, Schöpperle M, Pernil R, Schleiff E. Two TonB-dependent outer membrane transporters involved in heme uptake in Anabaena sp. PCC 7120. MICROBIAL CELL (GRAZ, AUSTRIA) 2024; 11:16-28. [PMID: 38234586 PMCID: PMC10792254 DOI: 10.15698/mic2024.01.812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/17/2023] [Revised: 11/03/2023] [Accepted: 11/13/2023] [Indexed: 01/19/2024]
Abstract
Low availability of micronutrients such as iron has enforced the evolution of uptake systems in all kingdoms of life. In Gram-negative bacteria, outer membrane, periplasmatic and plasma membrane localized proteins facilitate the uptake of iron-loaded chelators, which are energized by TonB proteins. The specificity of different uptake systems likely depends either on the endogenously produced siderophore or on the bioavailability of iron-chelator complexes in the environment. Hence, an uptake system for schizokinen produced by the model cyanobacterium Anabaena sp. PCC 7120 exists, while bioinformatics analysis suggests the existence of additional systems, likely for uptake of xenosiderophores. Consistently, proteins encoded by alr2153 (hutA1) and alr3242 (hutA2) are assigned as outer membrane heme transporters. Indeed, Anabaena sp. PCC 7120 can utilize external heme as an iron source. The addition of heme resulted in an induction of genes involved in heme degradation and chlorophyll a synthesis and in an increase of the chlorophyll a content. Moreover, iron starvation induced the expression of hutA1, while the addition of heme led to its repression. Remarkably, the addition of a high concentration of heme but not iron starvation resulted in hutA2 induction. Plasmid insertion mutants of both genes exhibited a reduced capacity to recover from iron starvation by heme addition, which indicates a dependence of heme uptake on functional HutA1 and HutA2 proteins. The structural model generated by bioinformatics methods is further in agreement with a role in heme uptake. Thus, we provide evidence that Anabaena sp. PCC 7120 uses a heme uptake system in parallel to other iron acquisition systems.
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Affiliation(s)
- Julia Graf
- Institute for Molecular Biosciences, Goethe University Frankfurt, Max von Laue Str. 9, 60438 Frankfurt, Germany
| | - Martin Schöpperle
- Institute for Molecular Biosciences, Goethe University Frankfurt, Max von Laue Str. 9, 60438 Frankfurt, Germany
- Current address: Lonza Cologne GmbH, Köln, Germany:
| | - Rafael Pernil
- Institute for Molecular Biosciences, Goethe University Frankfurt, Max von Laue Str. 9, 60438 Frankfurt, Germany
| | - Enrico Schleiff
- Institute for Molecular Biosciences, Goethe University Frankfurt, Max von Laue Str. 9, 60438 Frankfurt, Germany
- Frankfurt Institute for Advanced Studies, Ruth-Moufang-Straße 1, 60438 Frankfurt, Germany
- Buchmann Institute for Molecular Life Sciences, Max von Laue Str. 11, 60438 Frankfurt, Germany
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Heerah KM, Reader HE. Towards the identification of humic ligands associated with iron transport through a salinity gradient. Sci Rep 2022; 12:15545. [PMID: 36109552 PMCID: PMC9477803 DOI: 10.1038/s41598-022-19618-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 08/31/2022] [Indexed: 11/30/2022] Open
Abstract
Humic ligands from boreal rivers have been identified as important sources of iron-binding ligands to the coastal marine environment but remain poorly characterized. A novel method using Fourier transformed infrared spectroscopy (FTIR) was used to identify and quantify iron-binding ligands present in a boreal river in Newfoundland, Canada. 20 to 35% of the total iron load was carried through an artificial salinity gradient, and remained in solution at 35 salinity. Using FTIR combined with linear regression and 2D correlation analysis, we identified two pools of organic ligands, with different behaviour with regards to iron across the salinity gradient. The weaker ligand pool consisted of alkenes, ethers, and esters, and was found to release iron to flocculation at low salinities, and not contribute to iron transport into the marine environment. The stronger ligand group contained carboxylic acids and aliphatic functional groups. This group appears to contain two subgroups, one which was able to retain iron in the dissolved phase at 35 salinity, and another that flocculated out with iron across the salinity gradient. The strong ligands that retain iron in solution through the salinity gradient provide a much-needed source of the micronutrient to the coastal and marine environment, while the other subgroup sequesters iron and carbon in estuarine sediments. The balance between these two subgroups appears to be controlled by the hydrographic and weather conditions at the time of sampling, suggesting a dynamic ligand-iron relationship throughout the year, impacting the biogeochemical cycles of both iron and carbon in contrasting ways.
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Wu Y, Yang G, Xu L, Yu R, Huang X, Qiu W, Guo Y. Effects of zinc and iron on the abundance of Microcystis in Lake Taihu under green light and turbulence conditions. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:37791-37803. [PMID: 35067881 DOI: 10.1007/s11356-021-18089-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Accepted: 12/09/2021] [Indexed: 06/14/2023]
Abstract
Trace element is one of the important factors affecting the growth of Microcystis. The effects of zinc (0.4 mg/L) and iron (2 mg/L) on the abundance of Microcystis in Lake Taihu were investigated under continuous turbulence and green light conditions in a microcosm experiment. The study results showed that the abundance of Microcystis in the zinc treatment and the iron treatment group was 8.30% and 214% of that in the control group at the end of the experiment, respectively. The proportion of Cyanobacteria in the total phytoplankton biomass in the control, iron treatment, and zinc treatment group decreased from 99.99% at the beginning of the experiment to 13%, 18%, and 1% at the end of the experiment, respectively. At the end of the microcosm experiment, the phytoplankton community was dominated by Bacillariophyta in the control group, accounting for 63%, but it was dominated by Chlorophyta in the zinc treatment and the iron treatment group, accounting for 89% and 42%, respectively. The study results showed that under green light and turbulence, 0.4 mg/L zinc remarkably decreased the abundance of Microcystis, but 2 mg/L iron effectively increased the number of Microcystis and other algae. This research results provided a new idea for controlling Microcystis blooms.
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Affiliation(s)
- Yunrui Wu
- School of Environment and Civil Engineering, Jiangnan University, Wuxi, 214122, China
| | - Guijun Yang
- School of Environment and Civil Engineering, Jiangnan University, Wuxi, 214122, China.
| | - Lei Xu
- School of Environment and Civil Engineering, Jiangnan University, Wuxi, 214122, China
| | - Ruipeng Yu
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, 214122, Jiangsu, China
| | - Xiaofeng Huang
- Wuxi Taihu Lake Restoration Co., Ltd, Wuxi, 214062, China
| | - Weijian Qiu
- Wuxi Taihu Lake Restoration Co., Ltd, Wuxi, 214062, China
| | - Yun Guo
- Wuxi Taihu Lake Restoration Co., Ltd, Wuxi, 214062, China
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Functional Diversity of TonB-Like Proteins in the Heterocyst-Forming Cyanobacterium Anabaena sp. PCC 7120. mSphere 2021; 6:e0021421. [PMID: 34787445 PMCID: PMC8597729 DOI: 10.1128/msphere.00214-21] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The TonB-dependent transport of scarcely available substrates across the outer membrane is a conserved feature in Gram-negative bacteria. The plasma membrane-embedded TonB-ExbB-ExbD accomplishes complex functions as an energy transducer by physically interacting with TonB-dependent outer membrane transporters (TBDTs). TonB mediates structural rearrangements in the substrate-loaded TBDTs that are required for substrate translocation into the periplasm. In the model heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120, four TonB-like proteins have been identified. Out of these TonB3 accomplishes the transport of ferric schizokinen, the siderophore which is secreted by Anabaena to scavenge iron. In contrast, TonB1 (SjdR) is exceptionally short and not involved in schizokinen transport. The proposed function of SjdR in peptidoglycan structuring eliminates the protein from the list of TonB proteins in Anabaena. Compared with the well-characterized properties of SjdR and TonB3, the functions of TonB2 and TonB4 are yet unknown. Here, we examined tonB2 and tonB4 mutants for siderophore transport capacities and other specific phenotypic features. Both mutants were not or only slightly affected in schizokinen transport, whereas they showed decreased nitrogenase activity in apparently normal heterocysts. Moreover, the cellular metal concentrations and pigment contents were altered in the mutants, most pronouncedly in the tonB2 mutant. This strain showed an altered susceptibility toward antibiotics and SDS and formed cell aggregates when grown in liquid culture, a phenotype associated with an elevated lipopolysaccharide (LPS) production. Thus, the TonB-like proteins in Anabaena appear to take over distinct functions, and the mutation of TonB2 strongly influences outer membrane integrity. IMPORTANCE The genomes of many organisms encode more than one TonB protein, and their number does not necessarily correlate with that of TonB-dependent outer membrane transporters. Consequently, specific as well as redundant functions of the different TonB proteins have been identified. In addition to a role in uptake of scarcely available nutrients, including iron complexes, TonB proteins are related to virulence, flagellum assembly, pilus localization, or envelope integrity, including antibiotic resistance. The knowledge about the function of TonB proteins in cyanobacteria is limited. Here, we compare the four TonB proteins of Anabaena sp. strain PCC 7120, providing evidence that their functions are in part distinct, since mutants of these proteins exhibit specific features but also show some common impairments.
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Sá F, Longhini CM, Costa ES, da Silva CA, Cagnin RC, Gomes LEDO, Lima AT, Bernardino AF, Neto RR. Time-sequence development of metal(loid)s following the 2015 dam failure in the Doce river estuary, Brazil. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 769:144532. [PMID: 33485202 DOI: 10.1016/j.scitotenv.2020.144532] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 12/10/2020] [Accepted: 12/12/2020] [Indexed: 06/12/2023]
Abstract
In the context of the Doce river (Southeast Brazil) Fundão dam disaster in 2015, we monitored the changes in concentrations of metal(loid)s in water and sediment and their particulate and dissolved partitioning over time. Samples were collected before, during, and after the mine tailings arrival to the Doce river estuary (pre-impact: 12, 10, 3 and 1 day; acute stage: tailing day - TD and 1 day after - DA; chronic stage: 3 months and 1 year post-disaster). Our results show that metal(loid) concentrations significantly increased with time after the disaster and changed their chemical partitioning in the water. 35.2 mg Fe L-1 and 14.4 mg Al L-1 were observed in the total (unfiltered) water during the acute stage, while aqueous Al, As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Se and Zn concentrations all exceeded both Brazilian and international safe levels for water quality. The Al, Fe and Pb partitioning coefficient log (Kd) decrease in the acute stage could be related to the high colloid content in the tailings. We continued to observe high concentrations for Al, Ba, Cd, Cr, Cu, Fe, V and Zn mainly in the particulate fraction during the chronic stage. Furthermore, the Doce river estuary had been previously contaminated by As, Ba, Cr, Cu, Mn, Ni and Pb, with a further increase in sediment through the tailing release (e.g. 9-fold increase for Cr, from 3.61 ± 2.19 μg g-1 in the pre-impact to 32.16 ± 20.94 μg·g-1 in the chronic stage). Doce river sediments and original tailing samples were similar in metal(loid) composition for Al, As, Cd, Cr, Cu, Fe, V and Zn. As a result, these elements could be used as geochemical markers of the Fundão tailings and considering other key parameters to define a baseline for monitoring the impacts of this environmental disaster.
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Affiliation(s)
- Fabian Sá
- Laboratório de Geoquímica Ambiental e Poluição Marinha, Departamento de Oceanografia e Ecologia, Universidade Federal do Espírito Santo, Av. Fernando Ferrari, 514, Goiabeiras, Vitória, ES 29055-460, Brazil.
| | - Cybelle Menolli Longhini
- Laboratório de Geoquímica Ambiental e Poluição Marinha, Departamento de Oceanografia e Ecologia, Universidade Federal do Espírito Santo, Av. Fernando Ferrari, 514, Goiabeiras, Vitória, ES 29055-460, Brazil
| | - Eduardo Schettini Costa
- Laboratório de Geoquímica Ambiental e Poluição Marinha, Departamento de Oceanografia e Ecologia, Universidade Federal do Espírito Santo, Av. Fernando Ferrari, 514, Goiabeiras, Vitória, ES 29055-460, Brazil
| | - Cesar Alexandro da Silva
- Laboratório de Geoquímica Ambiental e Poluição Marinha, Departamento de Oceanografia e Ecologia, Universidade Federal do Espírito Santo, Av. Fernando Ferrari, 514, Goiabeiras, Vitória, ES 29055-460, Brazil
| | - Renata Caiado Cagnin
- Laboratório de Geoquímica Ambiental e Poluição Marinha, Departamento de Oceanografia e Ecologia, Universidade Federal do Espírito Santo, Av. Fernando Ferrari, 514, Goiabeiras, Vitória, ES 29055-460, Brazil
| | - Luiz Eduardo de Oliveira Gomes
- Grupo de Ecologia Bentônica, Departamento de Oceanografia e Ecologia, Universidade Federal do Espírito Santo, Av. Fernando Ferrari, 514, Goiabeiras, Vitória, ES 29055-460, Brazil
| | - Ana Teresa Lima
- Laboratório de Geoquímica Ambiental e Poluição Marinha, Departamento de Oceanografia e Ecologia, Universidade Federal do Espírito Santo, Av. Fernando Ferrari, 514, Goiabeiras, Vitória, ES 29055-460, Brazil; Department of Civil Engineering, Technical University of Denmark, Lyngby, Denmark
| | - Angelo Fraga Bernardino
- Grupo de Ecologia Bentônica, Departamento de Oceanografia e Ecologia, Universidade Federal do Espírito Santo, Av. Fernando Ferrari, 514, Goiabeiras, Vitória, ES 29055-460, Brazil
| | - Renato Rodrigues Neto
- Laboratório de Geoquímica Ambiental e Poluição Marinha, Departamento de Oceanografia e Ecologia, Universidade Federal do Espírito Santo, Av. Fernando Ferrari, 514, Goiabeiras, Vitória, ES 29055-460, Brazil
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Friedland G, Grüneberg B, Hupfer M. Geochemical signatures of lignite mining products in sediments downstream a fluvial-lacustrine system. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 760:143942. [PMID: 33348154 DOI: 10.1016/j.scitotenv.2020.143942] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 11/10/2020] [Accepted: 11/16/2020] [Indexed: 06/12/2023]
Abstract
As a result of the open-cast lignite mining in the Lusatian region of north-eastern Germany, large amounts of iron, sulphate, trace metals, and aluminium are fed into the groundwater and small streams that discharge into the River Spree, which ultimately flows through urban Berlin. In this study, we examined whether the input of these mining products leads to longitudinal gradients in element compositions and mineral formations in the riverine sediments. The signatures of fluvial and interconnected lacustrine sediments along a 190-km flow section were evaluated via principal component analysis to define the impact range of the open-cast products. These products clearly showed a sediment impact range of at least ~90 km downstream of the mining area. In particular, nickel and cobalt readily co-precipitate with iron, while sedimentary sulphur initially increases and therefore shows a longer impact range than amorphous iron oxy-hydroxides. These findings further demonstrate that sulphur and iron have different transport mechanisms. Although sulphate concentrations in the river waters of Berlin are still high, sedimentary iron and sulphur contents at the city border are only slightly higher than at the reference point close to the source of River Spree. The strongly diminished but still present mining signature in urban Berlin is replaced by an urban signature characterised by high levels of zinc, chromium, lead, and copper.
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Affiliation(s)
- Giulia Friedland
- Leibniz Institute of Freshwater Ecology and Inland Fisheries, Department of Chemical Analytics and Biogeochemistry, Müggelseedamm 301, D-12587 Berlin, Germany; Brandenburg University of Technology Cottbus-Senftenberg, Department of Freshwater Conservation, Seestraße 45, D-15526 Bad Saarow, Germany.
| | - Björn Grüneberg
- Brandenburg University of Technology Cottbus-Senftenberg, Department of Freshwater Conservation, Seestraße 45, D-15526 Bad Saarow, Germany; Landeslabor Berlin-Brandenburg, Rudower Chaussee 39, D-12489 Berlin, Germany
| | - Michael Hupfer
- Leibniz Institute of Freshwater Ecology and Inland Fisheries, Department of Chemical Analytics and Biogeochemistry, Müggelseedamm 301, D-12587 Berlin, Germany
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Hunnestad AV, Vogel AIM, Armstrong E, Digernes MG, Ardelan MV, Hohmann-Marriott MF. From the Ocean to the Lab-Assessing Iron Limitation in Cyanobacteria: An Interface Paper. Microorganisms 2020; 8:E1889. [PMID: 33260337 PMCID: PMC7760322 DOI: 10.3390/microorganisms8121889] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 11/25/2020] [Accepted: 11/26/2020] [Indexed: 12/22/2022] Open
Abstract
Iron is an essential, yet scarce, nutrient in marine environments. Phytoplankton, and especially cyanobacteria, have developed a wide range of mechanisms to acquire iron and maintain their iron-rich photosynthetic machinery. Iron limitation studies often utilize either oceanographic methods to understand large scale processes, or laboratory-based, molecular experiments to identify underlying molecular mechanisms on a cellular level. Here, we aim to highlight the benefits of both approaches to encourage interdisciplinary understanding of the effects of iron limitation on cyanobacteria with a focus on avoiding pitfalls in the initial phases of collaboration. In particular, we discuss the use of trace metal clean methods in combination with sterile techniques, and the challenges faced when a new collaboration is set up to combine interdisciplinary techniques. Methods necessary for producing reliable data, such as High Resolution Inductively Coupled Plasma Mass Spectrometry (HR-ICP-MS), Flow Injection Analysis Chemiluminescence (FIA-CL), and 77K fluorescence emission spectroscopy are discussed and evaluated and a technical manual, including the preparation of the artificial seawater medium Aquil, cleaning procedures, and a sampling scheme for an iron limitation experiment is included. This paper provides a reference point for researchers to implement different techniques into interdisciplinary iron studies that span cyanobacteria physiology, molecular biology, and biogeochemistry.
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Affiliation(s)
- Annie Vera Hunnestad
- Department of Chemistry, Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway; (A.V.H.); (M.G.D.)
| | - Anne Ilse Maria Vogel
- PhotoSynLab, Department of Biotechnology and Food Science, Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway; (A.I.M.V.); (M.F.H.-M.)
| | - Evelyn Armstrong
- NIWA/University of Otago Research Centre for Oceanography, Department of Chemistry, University of Otago, 9054 Dunedin, New Zealand;
| | - Maria Guadalupe Digernes
- Department of Chemistry, Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway; (A.V.H.); (M.G.D.)
| | - Murat Van Ardelan
- Department of Chemistry, Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway; (A.V.H.); (M.G.D.)
| | - Martin Frank Hohmann-Marriott
- PhotoSynLab, Department of Biotechnology and Food Science, Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway; (A.I.M.V.); (M.F.H.-M.)
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8
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Lin B, Xu J, Yu C, Chen L, Lu M, Xie X. A multi-parameter in-situ water quality analyzer based on a portable document scanner and 3D printed self-sampling cells. Anal Chim Acta 2020; 1101:176-183. [PMID: 32029109 DOI: 10.1016/j.aca.2019.12.034] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2019] [Revised: 11/17/2019] [Accepted: 12/14/2019] [Indexed: 11/16/2022]
Abstract
This research introduced a new low-cost and multi-parameter analyzer for in-situ measurements of typical nutrients in water bodies. The analyzer consisted of color detection and chromogenic reaction modules. The self-sampling action of the 3D printed sampling/reaction cells was achieved with the cooperative application of rubber bands and dissolvable thread. The target analytes in the collected water sample reacted with the chromogenic reagents that were diffused from the pre-placed glass wool in the cell, producing color compounds. A portable document scanner was employed as a multi-parameter in-situ detector to record the image of the colored solutions in all five cells simultaneously. Based on the image, the corrected grayscale values were derived for target analyte quantitation. The relationships between grayscale values and concentrations of target analytes were established, and the temperature effects were studied. In addition, the practicability of the analyzer was demonstrated by in-situ experiments carried out in four different sites, including a creek, a river dock, a reservoir and a secondary settling tank in a wastewater treatment facility. The results indicated that the analyzer could be used for in-situ measuring of nutrients at μmol/L levels in the water. The nutrient concentrations obtained with the analyzer were comparable with those obtained with the standard methods. The presented analyzer provided new complementary ideas and methods for in-situ rapid measurement of nutrients and other target analytes in various water systems.
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Affiliation(s)
- Beichen Lin
- School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, 30332, Georgia, USA; Pen-Tung Sah Institute of Micro-Nano Science & Technology, Xiamen University, Xiamen, 361005, China
| | - Jin Xu
- State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, Xiamen, 361005, China
| | - Cecilia Yu
- School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, 30332, Georgia, USA
| | - Luodan Chen
- State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, Xiamen, 361005, China
| | - Miao Lu
- Pen-Tung Sah Institute of Micro-Nano Science & Technology, Xiamen University, Xiamen, 361005, China.
| | - Xing Xie
- School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, 30332, Georgia, USA.
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9
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Qiu Y, Wang Z, Huang Z, Liu F, Tang D, Liu J. Effect of four kinds of complexing iron on the process of iron uptake by Anabaena flos-aquae. MICROBIOLOGY-SGM 2020; 166:359-366. [PMID: 32022661 DOI: 10.1099/mic.0.000891] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
AbstractIron (Fe), which is a necessary micronutrient for algal growth, plays an important role in the physiological metabolism and enzymatic reactions of algae. This study aimed to investigate the absorption process of four kinds of complexing iron absorbed by Anabaena flos-aquae. Results showed that the absorptive capacity of A. flos-aquae to complex iron was inversely proportional to the stability of the complex bond of complex iron. Complex iron with weak binding ability can be quickly adsorbed by A. flos-aquae. The absorptive rate was as follows: ferric humate, ferric oxalate >ammonium ferric citrate >EDTA Fe. For EDTA-Fe with a strong binding ability, a moderate iron concentration (e.g. 0.6 mg l-1) is favourable for iron uptake by A. flos-aquae. Our experiments also revealed that the process of separating iron from complex iron before entering algal cells was probably as follows: iron complexed with organic ligands were firstly adsorbed on the surface of algae cells; afterwards, iron ions were captured by organic matter on the surface of algae cells, accompanied by the rupture of the bond between Fe3+ and ligand; finally, the Fe3+ entered into the cell of algae while the organic ligands returned to the medium.
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Affiliation(s)
- Yongting Qiu
- School of Civil and Transportation Engineering, Guangdong University of Technology, Guangzhou 510006, PR China
| | | | - Ziqi Huang
- School of Civil and Transportation Engineering, Guangdong University of Technology, Guangzhou 510006, PR China
| | - Feng Liu
- School of Civil and Transportation Engineering, Guangdong University of Technology, Guangzhou 510006, PR China
| | - Daijun Tang
- School of Civil and Transportation Engineering, Guangdong University of Technology, Guangzhou 510006, PR China
| | - Junxia Liu
- School of Civil and Transportation Engineering, Guangdong University of Technology, Guangzhou 510006, PR China
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10
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Fu QL, Fujii M, Natsuike M, Waite TD. Iron uptake by bloom-forming freshwater cyanobacterium Microcystis aeruginosa in natural and effluent waters. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2019; 247:392-400. [PMID: 30690235 DOI: 10.1016/j.envpol.2019.01.071] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 01/08/2019] [Accepted: 01/20/2019] [Indexed: 06/09/2023]
Abstract
Studies on Fe uptake by phytoplankton have been often conducted using artificial culture media. However, Fe chemistry in freshwater can be influenced by riverine anthropogenic impacts and other factors causing water quality changes. In this study, therefore, Fe uptake in natural (river and reservoir) and effluent waters was investigated for the notorious bloom-forming freshwater cyanobacterium Microcystis aeruginosa. To investigate the Fe uptake mechanism, a short-term incubational assay was conducted in the presence of light, Fe(II) ligand and Fe(III) reductant, with results consistently indicating that unchelated Fe(III) is the major substrate for Fe uptake by M. aeruginosa. Further assays using various freshwater samples indicated that Fe uptake is lower in natural waters compared to that of effluent waters and, interestingly, Fe uptake was found to be limited in natural waters. These results suggest that Fe limitation can be alleviated by the inflow of effluent waters. Statistical analysis with various water quality variables indicated that Fe availability is significantly influenced by concentrations of dissolved Fe and organic matter as well as specific UV absorbance (an index of aromaticity). Overall, findings of this study highlight that watershed anthropogenic activities exert important roles in Fe uptake by freshwater cyanobacteria via alteration of Fe speciation.
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Affiliation(s)
- Qing-Long Fu
- Department of Civil and Environmental Engineering, Tokyo Institute of Technology, Ookayama, Tokyo, Japan.
| | - Manabu Fujii
- Department of Civil and Environmental Engineering, Tokyo Institute of Technology, Ookayama, Tokyo, Japan.
| | - Masafumi Natsuike
- Department of Civil and Environmental Engineering, Tokyo Institute of Technology, Ookayama, Tokyo, Japan
| | - T David Waite
- School of Civil and Environmental Engineering, The University of New South Wales, Sydney, Australia
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11
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Fu Q, Yeung ACY, Fujii M, Neilan BA, Waite TD. Physiological responses of the freshwater N
2
‐fixing cyanobacterium
Raphidiopsis raciborskii
to Fe and N availabilities. Environ Microbiol 2019; 21:1211-1223. [DOI: 10.1111/1462-2920.14545] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Revised: 01/23/2019] [Accepted: 01/24/2019] [Indexed: 12/12/2022]
Affiliation(s)
- Qing‐Long Fu
- Department of Civil and Environmental Engineering Tokyo Institute of Technology Ookayama, Tokyo Japan
| | - Anna C. Y. Yeung
- School of Civil and Environmental Engineering The University of New South Wales Sydney Australia
| | - Manabu Fujii
- Department of Civil and Environmental Engineering Tokyo Institute of Technology Ookayama, Tokyo Japan
| | - Brett A. Neilan
- School of Environmental and Life Sciences The University of Newcastle Newcastle Australia
| | - T. David Waite
- School of Civil and Environmental Engineering The University of New South Wales Sydney Australia
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12
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Schorsch M, Kramer M, Goss T, Eisenhut M, Robinson N, Osman D, Wilde A, Sadaf S, Brückler H, Walder L, Scheibe R, Hase T, Hanke GT. A unique ferredoxin acts as a player in the low-iron response of photosynthetic organisms. Proc Natl Acad Sci U S A 2018; 115:E12111-E12120. [PMID: 30514818 PMCID: PMC6304933 DOI: 10.1073/pnas.1810379115] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Iron chronically limits aquatic photosynthesis, especially in marine environments, and the correct perception and maintenance of iron homeostasis in photosynthetic bacteria, including cyanobacteria, is therefore of global significance. Multiple adaptive mechanisms, responsive promoters, and posttranscriptional regulators have been identified, which allow cyanobacteria to respond to changing iron concentrations. However, many factors remain unclear, in particular, how iron status is perceived within the cell. Here we describe a cyanobacterial ferredoxin (Fed2), with a unique C-terminal extension, that acts as a player in iron perception. Fed2 homologs are highly conserved in photosynthetic organisms from cyanobacteria to higher plants, and, although they belong to the plant type ferredoxin family of [2Fe-2S] photosynthetic electron carriers, they are not involved in photosynthetic electron transport. As deletion of fed2 appears lethal, we developed a C-terminal truncation system to attenuate protein function. Disturbed Fed2 function resulted in decreased chlorophyll accumulation, and this was exaggerated in iron-depleted medium, where different truncations led to either exaggerated or weaker responses to low iron. Despite this, iron concentrations remained the same, or were elevated in all truncation mutants. Further analysis established that, when Fed2 function was perturbed, the classical iron limitation marker IsiA failed to accumulate at transcript and protein levels. By contrast, abundance of IsiB, which shares an operon with isiA, was unaffected by loss of Fed2 function, pinpointing the site of Fed2 action in iron perception to the level of posttranscriptional regulation.
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Affiliation(s)
- Michael Schorsch
- School of Biological and Chemical Sciences, Queen Mary University of London, E1 4NS London, United Kingdom
| | - Manuela Kramer
- School of Biological and Chemical Sciences, Queen Mary University of London, E1 4NS London, United Kingdom
| | - Tatjana Goss
- Plant Biochemistry, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany
| | - Marion Eisenhut
- Plant Biochemistry, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany
| | - Nigel Robinson
- Department of Biosciences, Durham University, DH1 3LE Durham, United Kingdom
| | - Deenah Osman
- Department of Biosciences, Durham University, DH1 3LE Durham, United Kingdom
| | - Annegret Wilde
- Institute of Biology III, University of Freiburg, 79104 Freiburg, Germany
| | - Shamaila Sadaf
- Institute of Chemistry of New Materials, University of Osnabrück, 49069 Osnabrück, Germany
| | - Hendrik Brückler
- Institute of Chemistry of New Materials, University of Osnabrück, 49069 Osnabrück, Germany
| | - Lorenz Walder
- Institute of Chemistry of New Materials, University of Osnabrück, 49069 Osnabrück, Germany
| | - Renate Scheibe
- Plant Physiology, University of Osnabrück, 49076 Osnabrück, Germany
| | - Toshiharu Hase
- Institute for Protein Research, Osaka University, Osaka 565-0871, Japan
| | - Guy T Hanke
- School of Biological and Chemical Sciences, Queen Mary University of London, E1 4NS London, United Kingdom;
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13
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Lebret K, Östman Ö, Langenheder S, Drakare S, Guillemette F, Lindström ES. High abundances of the nuisance raphidophyte Gonyostomum semen in brown water lakes are associated with high concentrations of iron. Sci Rep 2018; 8:13463. [PMID: 30194445 PMCID: PMC6128840 DOI: 10.1038/s41598-018-31892-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 08/28/2018] [Indexed: 11/09/2022] Open
Abstract
Algal blooms occur frequently in lakes and oceans and the causes and consequences of those are often studied. In this study, we focus on a less well known type of algal bloom by the freshwater raphidophyte Gonyostomum semen. This species’ abundance and occurrence is increasing, especially in brown water lakes, the most abundant lake type in the boreal zone. The aim of the study was to investigate which environmental factors are associated with G. semen by statistical evaluation of field data of 95 Swedish lakes over five years. Although we found G. semen to be associated with dark waters it was, contrary to our expectations, mainly high concentrations of iron, and only to a lesser extent high TOC (total organic carbon) concentrations, that were associated with blooms of G. semen. In addition, high phosphorus concentrations and low pH also appear to facilitate G. semen blooms. We suggest that browning of lakes caused by increased iron concentrations may decrease net heterotrophy by fostering heavy algal blooms, i.e. the opposite to commonly assumed effects of increased DOM (dissolved organic matter).
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Affiliation(s)
- Karen Lebret
- Department of Ecology and Genetics/Limnology, Uppsala University, Norbyvägen 18D, SE-752 36, Uppsala, Sweden. .,Centre for Ecology and Evolution in Microbial model Systems - EEMiS, Department of Biology and Environmental Science, Linnæus University, SE-391 82, Kalmar, Sweden.
| | - Örjan Östman
- Department of Aquatic Resources, Swedish University of Agricultural Sciences, Skolgatan 6, SE-742 42, Öregrund, Sweden
| | - Silke Langenheder
- Department of Ecology and Genetics/Limnology, Uppsala University, Norbyvägen 18D, SE-752 36, Uppsala, Sweden
| | - Stina Drakare
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences - SLU, PO Box 7050, SE-750 07, Uppsala, Sweden
| | - François Guillemette
- Research Center on Watershed - Aquatic Ecosystem Interactions (RIVE), Department of Environmental Sciences, Université du Québec à Trois-Rivières, Québec, Canada
| | - Eva S Lindström
- Department of Ecology and Genetics/Limnology, Uppsala University, Norbyvägen 18D, SE-752 36, Uppsala, Sweden
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14
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Leigh-Smith J, Reichelt-Brushett A, Rose AL. The characterization of iron (III) in seawater and related toxicity to early life stages of scleractinian corals. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2018; 37:1104-1114. [PMID: 29149480 DOI: 10.1002/etc.4043] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Revised: 09/21/2017] [Accepted: 11/14/2017] [Indexed: 06/07/2023]
Abstract
Currently toxicity data for iron (Fe) in seawater are limited; furthermore, these data are of poor quality as a result of the importance of Fe solubility in test solutions being overlooked. The present study characterized the solubility and lability of Fe(III) in seawater and then examined the effects of Fe(III) on the fertilization success and larval survival of the tropical marine scleractinian corals Acropora spathulata and Platygyra daedalea. We present the first assessment of the effects of Fe on the early life stages of scleractinian corals. Concentrations of both soluble and labile forms of Fe were very low, with dissolved Fe concentrations ≤0.195 mg/L in bioassay test solutions and chemical determinations revealing labile Fe concentrations ≤1.21 mg/L. For fertilization experiments, the median effect concentration (EC50) value for total Fe was 25 mg/L for the most sensitive species, P. daedalea, whereas the EC50 values for A. spathulata ranged between 40 and 66 mg/L. The median lethal concentration value for P. daedalea larval survival was 47 mg/L Fe after 72-h exposure. We provide Fe toxicity data for tropical marine keystone species that could be used to help generate more reliable guideline values for Fe in marine waters. Environ Toxicol Chem 2018;37:1104-1114. © 2017 SETAC.
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Affiliation(s)
- Justin Leigh-Smith
- Marine Ecology Research Centre, School of Environment, Science and Engineering, Southern Cross University, Lismore, New South Wales, Australia
| | - Amanda Reichelt-Brushett
- Marine Ecology Research Centre, School of Environment, Science and Engineering, Southern Cross University, Lismore, New South Wales, Australia
| | - Andrew L Rose
- Southern Cross GeoScience and School of Environment, Science and Engineering, Southern Cross University, Lismore, New South Wales, Australia
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