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Baker IR, Girguis PR. Sulfur cycling likely obscures dynamic biologically-driven iron redox cycling in contemporary methane seep environments. ENVIRONMENTAL MICROBIOLOGY REPORTS 2024; 16:e13263. [PMID: 38705733 PMCID: PMC11070330 DOI: 10.1111/1758-2229.13263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2023] [Accepted: 04/06/2024] [Indexed: 05/07/2024]
Abstract
Deep-sea methane seeps are amongst the most biologically productive environments on Earth and are often characterised by stable, low oxygen concentrations and microbial communities that couple the anaerobic oxidation of methane to sulfate reduction or iron reduction in the underlying sediment. At these sites, ferrous iron (Fe2+) can be produced by organoclastic iron reduction, methanotrophic-coupled iron reduction, or through the abiotic reduction by sulfide produced by the abundant sulfate-reducing bacteria at these sites. The prevalence of Fe2+in the anoxic sediments, as well as the availability of oxygen in the overlying water, suggests that seeps could also harbour communities of iron-oxidising microbes. However, it is unclear to what extent Fe2+ remains bioavailable and in solution given that the abiotic reaction between sulfide and ferrous iron is often assumed to scavenge all ferrous iron as insoluble iron sulfides and pyrite. Accordingly, we searched the sea floor at methane seeps along the Cascadia Margin for microaerobic, neutrophilic iron-oxidising bacteria, operating under the reasoning that if iron-oxidising bacteria could be isolated from these environments, it could indicate that porewater Fe2+ can persist is long enough for biology to outcompete pyritisation. We found that the presence of sulfate in our enrichment media muted any obvious microbially-driven iron oxidation with most iron being precipitated as iron sulfides. Transfer of enrichment cultures to sulfate-depleted media led to dynamic iron redox cycling relative to abiotic controls and sulfate-containing cultures, and demonstrated the capacity for biogenic iron (oxyhydr)oxides from a methane seep-derived community. 16S rRNA analyses revealed that removing sulfate drastically reduced the diversity of enrichment cultures and caused a general shift from a Gammaproteobacteria-domainated ecosystem to one dominated by Rhodobacteraceae (Alphaproteobacteria). Our data suggest that, in most cases, sulfur cycling may restrict the biological "ferrous wheel" in contemporary environments through a combination of the sulfur-adapted sediment-dwelling ecosystems and the abiotic reactions they influence.
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Affiliation(s)
- Isabel R. Baker
- Department of Organismic and Evolutionary BiologyHarvard UniversityCambridgeMassachusettsUSA
- Department of Earth and Planetary ScienceJohns Hopkins UniversityBaltimoreMarylandUSA
| | - Peter R. Girguis
- Department of Organismic and Evolutionary BiologyHarvard UniversityCambridgeMassachusettsUSA
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2
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Garry M, Farasin J, Drevillon L, Quaiser A, Bouchez C, Le Borgne T, Coffinet S, Dufresne A. Ferriphaselus amnicola strain GF-20, a new iron- and thiosulfate-oxidizing bacterium isolated from a hard rock aquifer. FEMS Microbiol Ecol 2024; 100:fiae047. [PMID: 38573825 PMCID: PMC11044966 DOI: 10.1093/femsec/fiae047] [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: 11/01/2023] [Revised: 02/18/2024] [Accepted: 04/03/2024] [Indexed: 04/06/2024] Open
Abstract
Ferriphaselus amnicola GF-20 is the first Fe-oxidizing bacterium isolated from the continental subsurface. It was isolated from groundwater circulating at 20 m depth in the fractured-rock catchment observatory of Guidel-Ploemeur (France). Strain GF-20 is a neutrophilic, iron- and thiosulfate-oxidizer and grows autotrophically. The strain shows a preference for low oxygen concentrations, which suggests an adaptation to the limiting oxygen conditions of the subsurface. It produces extracellular stalks and dreads when grown with Fe(II) but does not secrete any structure when grown with thiosulfate. Phylogenetic analyses and genome comparisons revealed that strain GF-20 is affiliated with the species F. amnicola and is strikingly similar to F. amnicola strain OYT1, which was isolated from a groundwater seep in Japan. Based on the phenotypic and phylogenetic characteristics, we propose that GF-20 represents a new strain within the species F. amnicola.
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Affiliation(s)
- Mélissa Garry
- Géosciences Rennes, CNRS, Univ Rennes, UMR 6118, Rennes, France
- OSUR, Univ Rennes, UMS 3343, Rennes, France
| | | | - Laetitia Drevillon
- Ecobio—Ecosystèmes, Biodiversité, Evolution, CNRS, Univ Rennes, UMR 6553, Rennes, France
| | - Achim Quaiser
- Ecobio—Ecosystèmes, Biodiversité, Evolution, CNRS, Univ Rennes, UMR 6553, Rennes, France
| | - Camille Bouchez
- Géosciences Rennes, CNRS, Univ Rennes, UMR 6118, Rennes, France
| | | | - Sarah Coffinet
- Ecobio—Ecosystèmes, Biodiversité, Evolution, CNRS, Univ Rennes, UMR 6553, Rennes, France
| | - Alexis Dufresne
- Ecobio—Ecosystèmes, Biodiversité, Evolution, CNRS, Univ Rennes, UMR 6553, Rennes, France
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3
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Chen Y, Li X, Liu T, Li F, Sun W, Young LY, Huang W. Metagenomic analysis of Fe(II)-oxidizing bacteria for Fe(III) mineral formation and carbon assimilation under microoxic conditions in paddy soil. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 851:158068. [PMID: 35987227 DOI: 10.1016/j.scitotenv.2022.158068] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 08/08/2022] [Accepted: 08/12/2022] [Indexed: 06/15/2023]
Abstract
Microbially mediated Fe(II) oxidation is prevalent and thought to be central to many biogeochemical processes in paddy soils. However, we have limited insights into the Fe(II) oxidation process in paddy fields, considered the world's largest engineered wetland, where microoxic conditions are ubiquitous. In this study, microaerophilic Fe(II) oxidizing bacteria (FeOB) from paddy soil were enriched in gradient tubes with FeS, FeCO3, and Fe3(PO4)2 as iron sources to investigate their capacity for Fe(II) oxidation and carbon assimilation. Results showed that the highest rate of Fe(II) oxidation (k = 0.836 mM d-1) was obtained in the FeCO3 tubes, and cells grown in the Fe3(PO4)2 tubes yielded maximum assimilation amounts of 13C-NaHCO3 of 1.74% on Day 15. Amorphous Fe(III) oxides were found in all the cell bands with iron substrates as a result of microbial Fe(II) oxidation. Metagenomics analysis of the enriched microbes targeted genes encoding iron oxidase Cyc2, oxygen-reducing terminal oxidase, and ribulose-bisphosphate carboxylase, with results indicated that the potential Fe(II) oxidizers include nitrate-reducing FeOB (Dechloromonas and Thiobacillus), Curvibacter, and Magnetospirillum. By combining cultivation-dependent and metagenomic approaches, our results found a number of FeOB from paddy soil under microoxic conditions, which provide insight into the complex biogeochemical interactions of iron and carbon within paddy fields. The contribution of the FeOB to the element cycling in rice-growing regions deserves further investigation.
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Affiliation(s)
- Yating Chen
- Institute for Disaster Management and Reconstruction, Sichuan University-Hong Kong Polytechnic University, Chengdu 610207, China
| | - Xiaomin Li
- SCNU Environmental Research Institute, Guangdong Provincial Key Laboratory of Chemical Pollution and Environmental Safety & MOE Key Laboratory of Theoretical Chemistry of Environment, South China Normal University, Guangzhou 510006, China.
| | - Tongxu Liu
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-Environmental Pollution Control and Management, Institute of Eco-Environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
| | - Fangbai Li
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-Environmental Pollution Control and Management, Institute of Eco-Environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China.
| | - Weimin Sun
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-Environmental Pollution Control and Management, Institute of Eco-Environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
| | - Lily Y Young
- Department of Environmental Sciences, Rutgers University, New Brunswick, NJ 08901, USA
| | - Weilin Huang
- Department of Environmental Sciences, Rutgers University, New Brunswick, NJ 08901, USA
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Shen J, Liu H, Zhou H, Chen R. Specific characteristics of the microbial community in the groundwater fluctuation zone. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:76066-76077. [PMID: 35665458 DOI: 10.1007/s11356-022-21166-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 05/25/2022] [Indexed: 06/15/2023]
Abstract
Groundwater level fluctuation is a common natural phenomenon that causes alternate changes in oxygen, moisture, and biogeochemical processes in sediments. Microbes are sensitive to these environmental changes. Therefore, a specific microbial community is proposed to form in the groundwater fluctuation zone (GFZ). The vertical distributions of microbial abundance, diversity, and functional microbes and genes in sediment profiles were investigated, focusing on the GFZ, using high-throughput 16S rRNA gene sequencing, qPCR, and the Functional Annotation of Prokaryotic Taxa (FAPROTAX) approach. The relationships between chemical variables and microbial community structure were investigated by redundancy analysis (RDA). Results showed that the microbial abundance and microbial community richness and diversity were higher in the sediments of the GFZ. The nitrate reducers prefer to stay just below the groundwater level in the GFZ. The predominant microbes in the GFZ functioned as nitrifiers and Fe-oxidizers. The specific community in the GFZ is mainly related to NO3- and Fe(III) in the sediment. Consequently, the biochemical processes nitrification and Fe- and Mn-oxidation sequentially happen above the nitrate-reduction zone near the groundwater level in the GFZ. These results provide new knowledge in the biogeochemistry cycle of the GFZ and its disturbance on the vertical distribution and transport of biogenic elements and contaminants.
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Affiliation(s)
- Junhao Shen
- School of Environmental Studies, China University of Geosciences, Wuhan, 430074, People's Republic of China
| | - Hui Liu
- School of Environmental Studies, China University of Geosciences, Wuhan, 430074, People's Republic of China.
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, 430074, People's Republic of China.
| | - Huazhong Zhou
- Plant Protection Station of Hubei Province, Wuhan, 430070, People's Republic of China
| | - Rong Chen
- School of Environmental Studies, China University of Geosciences, Wuhan, 430074, People's Republic of China
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5
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Lueder U, Maisch M, Jørgensen BB, Druschel G, Schmidt C, Kappler A. Growth of microaerophilic Fe(II)-oxidizing bacteria using Fe(II) produced by Fe(III) photoreduction. GEOBIOLOGY 2022; 20:421-434. [PMID: 35014744 DOI: 10.1111/gbi.12485] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 11/10/2021] [Accepted: 12/31/2021] [Indexed: 06/14/2023]
Abstract
Iron(II) (Fe(II)) can be formed by abiotic Fe(III) photoreduction, particularly when Fe(III) is organically complexed. Light-influenced environments often overlap or even coincide with oxic or microoxic geochemical conditions, for example, in sediments. So far, it is unknown whether microaerophilic Fe(II)-oxidizing bacteria are able to use the Fe(II) produced by Fe(III) photoreduction as electron donor. Here, we present an adaption of the established agar-stabilized gradient tube approach in comparison with liquid cultures for the cultivation of microaerophilic Fe(II)-oxidizing microorganisms by using a ferrihydrite-citrate mixture undergoing Fe(III) photoreduction as Fe(II) source. We quantified oxygen and Fe(II) gradients with amperometric and voltammetric microelectrodes and evaluated microbial growth by qPCR of 16S rRNA genes. We showed that gradients of dissolved Fe(II) (maximum Fe(II) concentration of 1.25 mM) formed in the gradient tubes when incubated in blue or UV light (400-530 nm or 350-400 nm). Various microaerophilic Fe(II)-oxidizing bacteria (Curvibacter sp. and Gallionella sp.) grew by oxidizing Fe(II) that was produced in situ by Fe(III) photoreduction. Best growth for these species, based on highest gene copy numbers, was observed in incubations using UV light in both liquid culture and gradient tubes containing 8 mM ferrihydrite-citrate mixtures (1:1), due to continuous light-induced Fe(II) formation. Microaerophilic Fe(II)-oxidizing bacteria contributed up to 40% to the overall Fe(II) oxidation within 24 h of incubation in UV light. Our results highlight the potential importance of Fe(III) photoreduction as a source of Fe(II) for Fe(II)-oxidizing bacteria by providing Fe(II) in illuminated environments, even under microoxic conditions.
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Affiliation(s)
- Ulf Lueder
- Geomicrobiology Group, Center for Applied Geoscience (ZAG), University of Tuebingen, Tuebingen, Germany
| | - Markus Maisch
- Geomicrobiology Group, Center for Applied Geoscience (ZAG), University of Tuebingen, Tuebingen, Germany
| | - Bo Barker Jørgensen
- Section for Microbiology, Department of Biology, Aarhus University, Aarhus, Denmark
| | - Gregory Druschel
- Department of Earth Sciences, Indiana University-Purdue University, Indianapolis, Indiana, USA
| | - Caroline Schmidt
- Geomicrobiology Group, Center for Applied Geoscience (ZAG), University of Tuebingen, Tuebingen, Germany
| | - Andreas Kappler
- Geomicrobiology Group, Center for Applied Geoscience (ZAG), University of Tuebingen, Tuebingen, Germany
- Section for Microbiology, Department of Biology, Aarhus University, Aarhus, Denmark
- Cluster of Excellence: EXC 2124: Controlling Microbes to Fight Infection, Tübingen, Germany
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6
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Oligo-heterotrophic Activity of Marinobacter subterrani Creates an Indirect Fe(II) Oxidation Phenotype in Gradient Tubes. Appl Environ Microbiol 2021; 87:e0136721. [PMID: 34586913 DOI: 10.1128/aem.01367-21] [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: 11/20/2022] Open
Abstract
Autotrophic bacteria utilizing Fe(II) as their energy and electron sources for growth affect multiple biogeochemical cycles. Some chemoheterotrophic bacteria have also been considered to exhibit an Fe(II) oxidation phenotype. For example, several Marinobacter strains have been reported to oxidize Fe(II) based on formation of oxidized iron bands in semi-solid gradient tubes that produce opposing concentration gradients of Fe(II) and oxygen. While gradient tubes are a simple and visually compelling method to test for Fe(II) oxidation, this method alone cannot confirm if, and to what extent, Fe(II) oxidation is linked to metabolism in chemoheterotrophic bacteria. Here we probe the possibility of protein-mediated and metabolic by-product-mediated Fe(II) oxidation in Marinobacter subterrani JG233, a chemoheterotroph previously proposed to oxidize Fe(II). Results from conditional and mutant studies, along with measurements of Fe(II) oxidation rates, suggest M. subterrani is unlikely to facilitate Fe(II) oxidation under microaerobic conditions. We conclude that the Fe(II) oxidation phenotype observed in gradient tubes inoculated with M. subterrani JG233 is a result of oligo-heterotrophic activity, shifting the location where oxygen dependent chemical Fe(II) oxidation occurs, rather than a biologically mediated process. IMPORTANCE Gradient tubes are the most commonly used method to isolate and identify neutrophilic Fe(II)-oxidizing bacteria. The formation of oxidized iron bands in gradient tubes provides a compelling assay to ascribe the ability to oxidize Fe(II) to autotrophic bacteria whose growth is dependent on Fe(II) oxidation. However, the physiological significance of Fe(II) oxidation in chemoheterotrophic bacteria is less well understood. Our work suggests that oligo-heterotrophic activity of certain bacteria may create a false-positive phenotype in gradient tubes by altering the location of the abiotic, oxygen-mediated oxidized iron band. Based on the results and analysis presented here, we caution against utilizing gradient tubes as the sole evidence for the capability of a strain to oxidize Fe(II) and that additional experiments are necessary to ascribe this phenotype to new isolates.
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7
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Huang J, Jones A, Waite TD, Chen Y, Huang X, Rosso KM, Kappler A, Mansor M, Tratnyek PG, Zhang H. Fe(II) Redox Chemistry in the Environment. Chem Rev 2021; 121:8161-8233. [PMID: 34143612 DOI: 10.1021/acs.chemrev.0c01286] [Citation(s) in RCA: 142] [Impact Index Per Article: 47.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Iron (Fe) is the fourth most abundant element in the earth's crust and plays important roles in both biological and chemical processes. The redox reactivity of various Fe(II) forms has gained increasing attention over recent decades in the areas of (bio) geochemistry, environmental chemistry and engineering, and material sciences. The goal of this paper is to review these recent advances and the current state of knowledge of Fe(II) redox chemistry in the environment. Specifically, this comprehensive review focuses on the redox reactivity of four types of Fe(II) species including aqueous Fe(II), Fe(II) complexed with ligands, minerals bearing structural Fe(II), and sorbed Fe(II) on mineral oxide surfaces. The formation pathways, factors governing the reactivity, insights into potential mechanisms, reactivity comparison, and characterization techniques are discussed with reference to the most recent breakthroughs in this field where possible. We also cover the roles of these Fe(II) species in environmental applications of zerovalent iron, microbial processes, biogeochemical cycling of carbon and nutrients, and their abiotic oxidation related processes in natural and engineered systems.
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Affiliation(s)
- Jianzhi Huang
- Department of Civil and Environmental Engineering, Case Western Reserve University, 2104 Adelbert Road, Cleveland, Ohio 44106, United States
| | - Adele Jones
- UNSW Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - T David Waite
- UNSW Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Yiling Chen
- Institute of Environmental and Ecological Engineering, Guangdong University of Technology, Guangzhou 510006, China
| | - Xiaopeng Huang
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Kevin M Rosso
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Andreas Kappler
- Geomicrobiology, Center for Applied Geosciences, University of Tuebingen, 72076 Tuebingen, Germany
| | - Muammar Mansor
- Geomicrobiology, Center for Applied Geosciences, University of Tuebingen, 72076 Tuebingen, Germany
| | - Paul G Tratnyek
- School of Public Health, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, Oregon 97239, United States
| | - Huichun Zhang
- Department of Civil and Environmental Engineering, Case Western Reserve University, 2104 Adelbert Road, Cleveland, Ohio 44106, United States
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8
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Tong H, Chen M, Lv Y, Liu C, Zheng C, Xia Y. Changes in the microbial community during microbial microaerophilic Fe(II) oxidation at circumneutral pH enriched from paddy soil. ENVIRONMENTAL GEOCHEMISTRY AND HEALTH 2021; 43:1305-1317. [PMID: 32975698 DOI: 10.1007/s10653-020-00725-w] [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: 01/12/2020] [Accepted: 09/15/2020] [Indexed: 06/11/2023]
Abstract
Fe(II)-oxidizing bacteria (FeOB) are important catalysts for iron cycling in iron-rich marine, groundwater, and freshwater environments. However, few studies have reported the distribution and diversity of these bacteria in flooded paddy soils. This study investigates the microbial structure and diversity of microaerophilic Fe(II)-oxidizing bacteria (mFeOB) and their possible role in Fe(II) oxidation in iron-rich paddy soils. Using enrichment experiments that employed serial transfers, the changes in microaerophilic microbial community were examined via 16S rRNA gene high-throughput sequencing. During enrichments, the Fe(II) oxidation rate decreased as transfers increased, and the maximum rate of Fe(II) oxidation was observed in the first transfer (0.197 mM day-1). Results from X-ray diffraction of minerals and scanning electron microscopy of the cell-mineral aggregates revealed that cell surfaces in all transfers were partly covered with amorphous iron oxide formed by FeOB. After four transfers, the phyla of Proteobacteria had a dominant presence that reached up to 95%. Compared with the original soil, the relative abundances of Cupriavidus, Massilia, Pseudomonas, Ralstonia, Sphingomonas, and Variovorax increased in FeS gradient tubes and became dominant genera after transfers. Cupriavidus, Pseudomonas, and Ralstonia have been identified as FeOB previously. Furthermore, the structure of the microbial community tended to be stable as transfers increased, indicating that other bacterial species might perform important roles in Fe(II) oxidation. These results suggest the potential involvement of mFeOB and these other microorganisms in the Fe(II)-oxidizing process of soils. It will be helpful for future studies to consider their role in related biogeochemical processes, such as transformation of organic matters and heavy metals.
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Affiliation(s)
- Hui Tong
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Guangdong Institute of Eco-environmental Science and Technology, Guangdong Academy of Sciences, Guangzhou, 510650, China
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China
| | - Manjia Chen
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Guangdong Institute of Eco-environmental Science and Technology, Guangdong Academy of Sciences, Guangzhou, 510650, China
| | - Yahui Lv
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Guangdong Institute of Eco-environmental Science and Technology, Guangdong Academy of Sciences, Guangzhou, 510650, China
| | - Chengshuai Liu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China.
- CAS Center for Excellence in Quaternary Science and Global Change, Xi'an, 710061, China.
| | - Chunju Zheng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China
| | - Yafei Xia
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China
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Kappler A, Bryce C, Mansor M, Lueder U, Byrne JM, Swanner ED. An evolving view on biogeochemical cycling of iron. Nat Rev Microbiol 2021; 19:360-374. [PMID: 33526911 DOI: 10.1038/s41579-020-00502-7] [Citation(s) in RCA: 183] [Impact Index Per Article: 61.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/08/2020] [Indexed: 01/23/2023]
Abstract
Biogeochemical cycling of iron is crucial to many environmental processes, such as ocean productivity, carbon storage, greenhouse gas emissions and the fate of nutrients, toxic metals and metalloids. Knowledge of the underlying processes involved in iron cycling has accelerated in recent years along with appreciation of the complex network of biotic and abiotic reactions dictating the speciation, mobility and reactivity of iron in the environment. Recent studies have provided insights into novel processes in the biogeochemical iron cycle such as microbial ammonium oxidation and methane oxidation coupled to Fe(III) reduction. They have also revealed that processes in the biogeochemical iron cycle spatially overlap and may compete with each other, and that oxidation and reduction of iron occur cyclically or simultaneously in many environments. This Review discusses these advances with particular focus on their environmental consequences, including the formation of greenhouse gases and the fate of nutrients and contaminants.
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Affiliation(s)
- Andreas Kappler
- Geomicrobiology, Center for Applied Geosciences, University of Tübingen, Tübingen, Germany.
| | - Casey Bryce
- School of Earth Sciences, University of Bristol, Bristol, UK
| | - Muammar Mansor
- Geomicrobiology, Center for Applied Geosciences, University of Tübingen, Tübingen, Germany
| | - Ulf Lueder
- Geomicrobiology, Center for Applied Geosciences, University of Tübingen, Tübingen, Germany
| | - James M Byrne
- School of Earth Sciences, University of Bristol, Bristol, UK
| | - Elizabeth D Swanner
- Department of Geological and Atmospheric Sciences, Iowa State University, Ames, IA, USA
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10
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Genomic Insights into Two Novel Fe(II)-Oxidizing Zetaproteobacteria Isolates Reveal Lifestyle Adaption to Coastal Marine Sediments. Appl Environ Microbiol 2020; 86:AEM.01160-20. [PMID: 32561582 DOI: 10.1128/aem.01160-20] [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: 05/15/2020] [Accepted: 06/13/2020] [Indexed: 11/20/2022] Open
Abstract
The discovery of the novel Zetaproteobacteria class greatly expanded our understanding of neutrophilic, microaerophilic microbial Fe(II) oxidation in marine environments. Despite molecular techniques demonstrating their global distribution, relatively few isolates exist, especially from low-Fe(II) environments. Furthermore, the Fe(II) oxidation pathways used by Zetaproteobacteria remain poorly understood. Here, we present the genomes (>99% genome completeness) of two Zetaproteobacteria, which are the only cultivated isolates originating from typical low-Fe [porewater Fe(II), 70 to 100 μM] coastal marine sediments. The two strains share <90% average nucleotide identity (ANI) with each other and <80% ANI with any other Zetaproteobacteria genome. The closest relatives were Mariprofundus aestuarium strain CP-5 and Mariprofundus ferrinatatus strain CP-8 (96 to 98% 16S rRNA gene sequence similarity). Fe(II) oxidation of strains KV and NF is most likely mediated by the putative Fe(II) oxidase Cyc2. Interestingly, the genome of strain KV also encodes a putative multicopper oxidase, PcoAB, which could play a role in Fe(II) oxidation, a pathway found only in two other Zetaproteobacteria genomes (Ghiorsea bivora TAG-1 and SCGC AB-602-C20). The strains show potential adaptations to fluctuating O2 concentrations, indicated by the presence of both cbb 3- and aa 3-type cytochrome c oxidases, which are adapted to low and high O2 concentrations, respectively. This is further supported by the presence of several oxidative-stress-related genes. In summary, our results reveal the potential Fe(II) oxidation pathways employed by these two novel chemolithoautotrophic Fe(II)-oxidizing species and the lifestyle adaptations which enable the Zetaproteobacteria to survive in coastal environments with low Fe(II) and regular redox fluctuations.IMPORTANCE Until recently, the importance and relevance of Zetaproteobacteria were mainly thought to be restricted to high-Fe(II) environments, such as deep-sea hydrothermal vents. The two novel Mariprofundus isolates presented here originate from typical low-Fe(II) coastal marine sediments. As well as being low in Fe(II), these environments are often subjected to fluctuating O2 concentrations and regular mixing by wave action and bioturbation. The discovery of two novel isolates highlights the importance of these organisms in such environments, as Fe(II) oxidation has been shown to impact nutrients and trace metals. Genome analysis of these two strains further supported their lifestyle adaptation and therefore their potential preference for coastal marine sediments, as genes necessary for surviving dynamic O2 concentrations and oxidative stress were identified. Furthermore, our analyses also expand our understanding of the poorly understood Fe(II) oxidation pathways used by neutrophilic, microaerophilic Fe(II) oxidizers.
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Iron is not everything: unexpected complex metabolic responses between iron-cycling microorganisms. ISME JOURNAL 2020; 14:2675-2690. [PMID: 32690937 PMCID: PMC7784907 DOI: 10.1038/s41396-020-0718-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 06/30/2020] [Accepted: 07/08/2020] [Indexed: 02/02/2023]
Abstract
Coexistence of microaerophilic Fe(II)-oxidizers and anaerobic Fe(III)-reducers in environments with fluctuating redox conditions is a prime example of mutualism, in which both partners benefit from the sustained Fe-pool. Consequently, the Fe-cycling machineries (i.e., metal-reducing or -oxidizing pathways) should be most affected during co-cultivation. However, contrasting growth requirements impeded systematic elucidation of their interactions. To disentangle underlying interaction mechanisms, we established a suboxic co-culture system of Sideroxydans sp. CL21 and Shewanella oneidensis. We showed that addition of the partner's cell-free supernatant enhanced both growth and Fe(II)-oxidizing or Fe(III)-reducing activity of each partner. Metabolites of the exometabolome of Sideroxydans sp. CL21 are generally upregulated if stimulated with the partner´s spent medium, while S. oneidensis exhibits a mixed metabolic response in accordance with a balanced response to the partner. Surprisingly, RNA-seq analysis revealed genes involved in Fe-cycling were not differentially expressed during co-cultivation. Instead, the most differentially upregulated genes included those encoding for biopolymer production, lipoprotein transport, putrescine biosynthesis, and amino acid degradation suggesting a regulated inter-species biofilm formation. Furthermore, the upregulation of hydrogenases in Sideroxydans sp. CL21 points to competition for H2 as electron donor. Our findings reveal that a complex metabolic and transcriptomic response, but not accelerated formation of Fe-end products, drive interactions of Fe-cycling microorganisms.
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Hädrich A, Taillefert M, Akob DM, Cooper RE, Litzba U, Wagner FE, Nietzsche S, Ciobota V, Rösch P, Popp J, Küsel K. Microbial Fe(II) oxidation by Sideroxydans lithotrophicus ES-1 in the presence of Schlöppnerbrunnen fen-derived humic acids. FEMS Microbiol Ecol 2020; 95:5381554. [PMID: 30874727 DOI: 10.1093/femsec/fiz034] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 03/14/2019] [Indexed: 11/14/2022] Open
Abstract
Controlled laboratory experiments were combined with field measurements to better understand the interactions between dissolved organic matter (DOM) and reduced iron in organic-rich peatlands. Addition of peat-derived humic acid extract (HA) to Sideroxydans lithotrophicus ES-1 liquid cultures led to higher cell numbers and up to 1.4 times higher Fe(II) oxidation rates compared to chemical controls. This effect was positively correlated with increasing HA concentrations. Similar Fe(III) (oxyhydr)oxide mineralogies were formed both abiotically and biotically irrespective of HA amendment, but minerals formed in the presence of ES-1 and HA were smaller. ES-1 growth with HA promoted aggregation of Fe(III) products in agarose-stabilized gradient tubes as shown by voltammetric profiling. In situ voltammetry in an acidic, iron-rich peatland revealed a gap between oxygen penetration and iron reduction that may reflect active Fe(II)-oxidizing microorganisms. The highest abundance of Fe(II) oxidizers Sideroxydans (4.9 × 107 gene copies gww-1) and Gallionella (1.5 × 107 gene copies gww-1) in the upper peat layer coincided with small-sized minerals resembling nanoparticulate ferrihydrite or goethite. Our results suggest that microbially mediated Fe(II) oxidation dominates in the presence of DOM leading to the formation of nano-sized biogenic Fe(III) (oxyhydr)oxides that might be readily bioavailable and likely important to iron and carbon cycling.
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Affiliation(s)
- Anke Hädrich
- Institute of Biodiversity, Friedrich Schiller University Jena, Dornburger Strasse 159, D-07743 Jena, Germany
| | - Martial Taillefert
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332-0340, USA
| | - Denise M Akob
- Institute of Biodiversity, Friedrich Schiller University Jena, Dornburger Strasse 159, D-07743 Jena, Germany.,Water Resource Mission Area, U.S. Geological Survey, 12201 Sunrise Valley Dr., MS 430, Reston, VA 20192, USA
| | - Rebecca E Cooper
- Institute of Biodiversity, Friedrich Schiller University Jena, Dornburger Strasse 159, D-07743 Jena, Germany
| | - Ulrike Litzba
- Institute of Biodiversity, Friedrich Schiller University Jena, Dornburger Strasse 159, D-07743 Jena, Germany
| | - Friedrich E Wagner
- Department of Physics, Technical University Munich, James Frank Strasse, D-85748 Garching, Germany
| | - Sandor Nietzsche
- Centre of Electron Microscopy, University Hospital Jena, Friedrich Schiller University Jena, Ziegelmühlenweg 1, D-07743 Jena, Germany
| | - Valerian Ciobota
- Institute of Physical Chemistry, Friedrich Schiller University Jena, Helmholtzweg 4, D-07743 Jena, Germany.,Rigaku Analytical Devices, Inc., 30 Upton Drive, Wilmington, MA 01887, USA
| | - Petra Rösch
- Institute of Physical Chemistry, Friedrich Schiller University Jena, Helmholtzweg 4, D-07743 Jena, Germany
| | - Jürgen Popp
- Institute of Photonic Technology, Friedrich Schiller University Jena, Albert-Einstein-Straße 9, D-07745 Jena, Germany
| | - Kirsten Küsel
- Institute of Biodiversity, Friedrich Schiller University Jena, Dornburger Strasse 159, D-07743 Jena, Germany.,German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz 5e, D-04103 Leipzig, Germany
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From Plant to Paddy—How Rice Root Iron Plaque Can Affect the Paddy Field Iron Cycling. SOIL SYSTEMS 2020. [DOI: 10.3390/soilsystems4020028] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Iron plaque on rice roots represents a sink and source of iron in paddy fields. However, the extent of iron plaque in impacting paddy field iron cycling is not yet fully deciphered. Here, we followed iron plaque formation during plant growth in laboratory-controlled setups containing a transparent soil matrix. Using image analysis, microsensor measurements, and mineral extractions, we demonstrate that radial oxygen loss (ROL) is the main driver for rhizosphere iron oxidation. While O2 was restricted to the vicinity of roots, root tips showed highest spatio-temporal variation in ROL (<5–50 µM) following diurnal patterns. Iron plaque covered >30% of the total root surface corresponding to 60–180 mg Fe(III) per gram dried root and gradually transformed from low-crystalline minerals (e.g., ferrihydrite) on root tips, to >20% higher-crystalline minerals (e.g., goethite) within 40 days. Iron plaque exposed to an Fe(III)-reducing Geobacter spp. culture resulted in 30% Fe(II) remobilization and >50% microbial transformation to Fe(II) minerals (e.g., siderite, vivianite, and Fe–S phases) or persisted by >15% as Fe(III) minerals. Based on the collected data, we estimated that iron plaque formation and reductive dissolution can impact more than 5% of the rhizosphere iron budget which has consequences for the (im)mobilization of soil contaminants and nutrients.
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Maisch M, Lueder U, Laufer K, Scholze C, Kappler A, Schmidt C. Contribution of Microaerophilic Iron(II)-Oxidizers to Iron(III) Mineral Formation. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:8197-8204. [PMID: 31203607 DOI: 10.1021/acs.est.9b01531] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Neutrophilic microbial aerobic oxidation of ferrous iron (Fe(II)) is restricted to pH-circumneutral environments characterized by low oxygen where microaerophilic Fe(II)-oxidizing microorganisms successfully compete with abiotic Fe(II) oxidation. However, accumulation of ferric (bio)minerals increases competition by stimulating abiotic surface-catalyzed heterogeneous Fe(II) oxidation. Here, we present an experimental approach that allows quantification of microbial and abiotic contribution to Fe(II) oxidation in the presence or initial absence of ferric (bio)minerals. We found that at 20 μM O2 and the initial absence of Fe(III) minerals, an iron(II)-oxidizing enrichment culture (99.6% similarity to Sideroxydans spp.) contributed 40% to the overall Fe(II) oxidation within approximately 26 h and oxidized up to 3.6 × 10-15 mol Fe(II) cell-1 h-1. Optimum O2 concentrations at which enzymatic Fe(II) oxidation can compete with abiotic Fe(II) oxidation ranged from 5 to 20 μM. Lower O2 levels limited biotic Fe(II) oxidation, while at higher O2 levels abiotic Fe(II) oxidation dominated. The presence of ferric (bio)minerals induced surface-catalytic heterogeneous abiotic Fe(II) oxidation and reduced the microbial contribution to Fe(II) oxidation from 40% to 10% at 10 μM O2. The obtained results will help to better assess the impact of microaerophilic Fe(II) oxidation on the biogeochemical iron cycle in a variety of environmental natural and anthropogenic settings.
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Affiliation(s)
- Markus Maisch
- Geomicrobiology, Center for Applied Geosciences , University of Tübingen , Tübingen 72074 , Germany
| | - Ulf Lueder
- Geomicrobiology, Center for Applied Geosciences , University of Tübingen , Tübingen 72074 , Germany
| | - Katja Laufer
- Department for Bioscience , Aarhus University , 8000 Aarhus , Denmark
| | - Caroline Scholze
- Department for Bioscience , Aarhus University , 8000 Aarhus , Denmark
| | - Andreas Kappler
- Geomicrobiology, Center for Applied Geosciences , University of Tübingen , Tübingen 72074 , Germany
- Department for Bioscience , Aarhus University , 8000 Aarhus , Denmark
| | - Caroline Schmidt
- Geomicrobiology, Center for Applied Geosciences , University of Tübingen , Tübingen 72074 , Germany
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McAllister SM, Moore RM, Gartman A, Luther GW, Emerson D, Chan CS. The Fe(II)-oxidizing Zetaproteobacteria: historical, ecological and genomic perspectives. FEMS Microbiol Ecol 2019; 95:fiz015. [PMID: 30715272 PMCID: PMC6443915 DOI: 10.1093/femsec/fiz015] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Accepted: 01/29/2019] [Indexed: 01/22/2023] Open
Abstract
The Zetaproteobacteria are a class of bacteria typically associated with marine Fe(II)-oxidizing environments. First discovered in the hydrothermal vents at Loihi Seamount, Hawaii, they have become model organisms for marine microbial Fe(II) oxidation. In addition to deep sea and shallow hydrothermal vents, Zetaproteobacteria are found in coastal sediments, other marine subsurface environments, steel corrosion biofilms and saline terrestrial springs. Isolates from a range of environments all grow by autotrophic Fe(II) oxidation. Their success lies partly in their microaerophily, which enables them to compete with abiotic Fe(II) oxidation at Fe(II)-rich oxic/anoxic transition zones. To determine the known diversity of the Zetaproteobacteria, we have used 16S rRNA gene sequences to define 59 operational taxonomic units (OTUs), at 97% similarity. While some Zetaproteobacteria taxa appear to be cosmopolitan, others are enriched by specific habitats. OTU networks show that certain Zetaproteobacteria co-exist, sharing compatible niches. These niches may correspond with adaptations to O2, H2 and nitrate availability, based on genomic analyses of metabolic potential. Also, a putative Fe(II) oxidation gene has been found in diverse Zetaproteobacteria taxa, suggesting that the Zetaproteobacteria evolved as Fe(II) oxidation specialists. In all, studies suggest that Zetaproteobacteria are widespread, and therefore may have a broad influence on marine and saline terrestrial Fe cycling.
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Affiliation(s)
- Sean M McAllister
- School of Marine Science and Policy, University of Delaware, 700 Pilottown Road, 204 Cannon Lab, Lewes, Delaware, USA 19958
| | - Ryan M Moore
- Center for Bioinformatics and Computational Biology, University of Delaware, 15 Innovation Way, 205 Delaware Biotechnology Institute, Newark, Delaware, USA 19711
| | - Amy Gartman
- School of Marine Science and Policy, University of Delaware, 700 Pilottown Road, 204 Cannon Lab, Lewes, Delaware, USA 19958
| | - George W Luther
- School of Marine Science and Policy, University of Delaware, 700 Pilottown Road, 204 Cannon Lab, Lewes, Delaware, USA 19958
| | - David Emerson
- Bigelow Laboratory for Ocean Sciences, 60 Bigelow Drive, East Boothbay, Maine, USA 04544
| | - Clara S Chan
- School of Marine Science and Policy, University of Delaware, 700 Pilottown Road, 204 Cannon Lab, Lewes, Delaware, USA 19958
- Department of Geological Sciences, University of Delaware, 101 Penny Hall, Newark, Delaware, USA 19716
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