1
|
Liu JB, Zhang H, Wang H, He B, Wang H, Jin R, Tian T. Remediation of arsenic- and nitrate-contaminated groundwater through iron-dependent autotrophic denitrifying culture. ENVIRONMENTAL RESEARCH 2024; 257:119239. [PMID: 38810825 DOI: 10.1016/j.envres.2024.119239] [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: 02/23/2024] [Revised: 05/11/2024] [Accepted: 05/26/2024] [Indexed: 05/31/2024]
Abstract
Groundwater contamination with arsenic and nitrate poses a pressing concern for the safety of local communities. Bioremediation, utilizing Fe(II)-oxidizing nitrate reducing bacteria, shows promise as a solution to this problem. However, the relatively weak environmental adaptability of a single bacterium hampers practical application. Therefore, this study explored the feasibility and characteristics of a mixed iron-dependent autotrophic denitrifying (IDAD) culture for effectively removing arsenic and nitrate from synthetic groundwater. The IDAD biosystem exhibited stable performace and arsenic resistance, even at a high As(III) concentration of 800 μg/L. Although the nitrogen removal efficiency of the IDAD biosystem decreased from 71.4% to 64.7% in this case, the arsenic concentration in the effluent remained below the standard (10 μg/L) set by WHO. The crystallinity of the lepidocrocite produced by the IDAD culture decreased with increasing arsenic concentration, but the relative abundance of the key iron-oxidizing bacteria norank_f_Gallionellaceae in the culture showed an opposite trend. Metagenomic analysis revealed that the IDAD culture possess arsenic detoxification pathways, including redox, methylation, and efflux of arsenic, which enable it to mitigate the adverse impact of arsenic stress. This study provides theoretical understanding and technical support for the remediation of arsenic and nitrate-contaminated groundwater using the IDAD culture.
Collapse
Affiliation(s)
- Jia-Bo Liu
- Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education, China), School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024, China
| | - Hongbin Zhang
- Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education, China), School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024, China
| | - Hefei Wang
- National Marine Environmental Monitoring Center, Dalian, 116023, China.
| | - Banghui He
- Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education, China), School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024, China
| | - Huixuan Wang
- Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education, China), School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024, China
| | - Ruofei Jin
- Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education, China), School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024, China
| | - Tian Tian
- Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education, China), School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024, China.
| |
Collapse
|
2
|
Yang G, Li S, Niu R, Hu M, Huang G, Pan D, Yan S, Liu T, Li X, Li F. Insights into nitrate-reducing Fe(II) oxidation by Diaphorobacter caeni LI3 T through kinetic, nitrogen isotope fractionation, and genome analyses. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 912:168720. [PMID: 38008321 DOI: 10.1016/j.scitotenv.2023.168720] [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: 09/07/2023] [Revised: 11/17/2023] [Accepted: 11/18/2023] [Indexed: 11/28/2023]
Abstract
Nitrate (NO3-)-reducing Fe(II) oxidation (NRFO) is prevalent in anoxic environments. However, it is uncertain in which step(s) the biological Fe(II) oxidation is coupled with denitrification during NRFO. In this study, a heterotrophic NRFO bacterium, Diaphorobacter caeni LI3T, was isolated from paddy soil and used to investigate the transformation of Fe(II) and nitrogen as well as nitrogen isotopic fractionation (δ15N-N2O) during NRFO. Fe(II) oxidation was observed in the Cell+NO3- +Fe(II), Cell+NO2- + Fe(II), and NO2- + Fe(II) treatments, resulting in precipitation of amorphous Fe(III) minerals and lepidocrocite on the surface and in the periplasm of cells. The presence of Fe(II) slightly accelerated microbial NO3- reduction in the Cell+NO3- + Fe(II) treatment relative to the Cell+NO3- treatment, but slowed down the NO2- reduction in the Cell+NO2- + Fe(II) treatment relative to the Cell+NO2- treatment likely due to cell encrustation that blocking microbial NO2- reduction in the periplasm. The δ15N-N2O results in the Cell+NO3- + Fe(II) treatment were close to those in the Cell+NO3- and Cell+NO2- treatments, indicating that the accumulative N2O is primarily of biological origin during NRFO. The genome analysis found a complete set of denitrification and oxidative phosphorylation genes in strain LI3T, the metabolic pathways of which were closely related with cyc2 and cytc as indicated by protein-protein interactions network analysis. It is proposed that Fe(II) oxidation is catalyzed by the outer membrane protein Cyc2, with the resulting electrons being transferred to the nitrite reductase NirS via CytC in the periplasm, and the CytC can also accept electrons from the oxidative phosphorylation in the cytoplasmic membrane. Overall, our findings provide new insights into the potential pathways of biological Fe(II) oxidation coupled with nitrate reduction in heterotrophic NRFO bacteria.
Collapse
Affiliation(s)
- Guang Yang
- 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
| | - Shuang 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; Institute of Nanfan & Seed Industry, Guangdong Academy of Sciences, Guangzhou 510316, China
| | - Rumiao Niu
- 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
| | - Min Hu
- 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
| | - Guoyong Huang
- 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
| | - Dandan Pan
- 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
| | - Siyao Yan
- 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
| | - 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.
| | - 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
| |
Collapse
|
3
|
Corbera-Rubio F, Stouten GR, Bruins J, Dost SF, Merkel AY, Müller S, van Loosdrecht MCM, van Halem D, Laureni M. " Candidatus Siderophilus nitratireducens": a putative nap-dependent nitrate-reducing iron oxidizer within the new order Siderophiliales. ISME COMMUNICATIONS 2024; 4:ycae008. [PMID: 38577582 PMCID: PMC10993476 DOI: 10.1093/ismeco/ycae008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/16/2023] [Revised: 01/03/2024] [Accepted: 01/17/2024] [Indexed: 04/06/2024]
Abstract
Nitrate leaching from agricultural soils is increasingly found in groundwater, a primary source of drinking water worldwide. This nitrate influx can potentially stimulate the biological oxidation of iron in anoxic groundwater reservoirs. Nitrate-dependent iron-oxidizing (NDFO) bacteria have been extensively studied in laboratory settings, yet their ecophysiology in natural environments remains largely unknown. To this end, we established a pilot-scale filter on nitrate-rich groundwater to elucidate the structure and metabolism of nitrate-reducing iron-oxidizing microbiomes under oligotrophic conditions mimicking natural groundwaters. The enriched community stoichiometrically removed iron and nitrate consistently with the NDFO metabolism. Genome-resolved metagenomics revealed the underlying metabolic network between the dominant iron-dependent denitrifying autotrophs and the less abundant organoheterotrophs. The most abundant genome belonged to a new Candidate order, named Siderophiliales. This new species, "Candidatus Siderophilus nitratireducens," carries genes central genes to iron oxidation (cytochrome c cyc2), carbon fixation (rbc), and for the sole periplasmic nitrate reductase (nap). Using thermodynamics, we demonstrate that iron oxidation coupled to nap based dissimilatory reduction of nitrate to nitrite is energetically favorable under realistic Fe3+/Fe2+ and NO3-/NO2- concentration ratios. Ultimately, by bridging the gap between laboratory investigations and nitrate real-world conditions, this study provides insights into the intricate interplay between nitrate and iron in groundwater ecosystems, and expands our understanding of NDFOs taxonomic diversity and ecological role.
Collapse
Affiliation(s)
| | - Gerben R Stouten
- Delft University of Technology, Stevinweg 1, 2628 CN Delft, the Netherlands
| | | | - Simon F Dost
- WMD Water Company Drenthe, Lauwers 3, 9405 BL Assen, the Netherlands
| | - Alexander Y Merkel
- Winogradsky Institute of Microbiology, Research Center of Biotechnology, Russian Academy of Sciences, 60 let Oktjabrja pr-t, 7, bld. 2, 117312 Moscow, Russia
| | - Simon Müller
- Delft University of Technology, Stevinweg 1, 2628 CN Delft, the Netherlands
| | | | - Doris van Halem
- Delft University of Technology, Stevinweg 1, 2628 CN Delft, the Netherlands
| | - Michele Laureni
- Delft University of Technology, Stevinweg 1, 2628 CN Delft, the Netherlands
| |
Collapse
|
4
|
Hoover RL, Keffer JL, Polson SW, Chan CS. Gallionellaceae pangenomic analysis reveals insight into phylogeny, metabolic flexibility, and iron oxidation mechanisms. mSystems 2023; 8:e0003823. [PMID: 37882557 PMCID: PMC10734462 DOI: 10.1128/msystems.00038-23] [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: 01/25/2023] [Accepted: 09/20/2023] [Indexed: 10/27/2023] Open
Abstract
IMPORTANCE Neutrophilic iron-oxidizing bacteria (FeOB) produce copious iron (oxyhydr)oxides that can profoundly influence biogeochemical cycles, notably the fate of carbon and many metals. To fully understand environmental microbial iron oxidation, we need a thorough accounting of iron oxidation mechanisms. In this study, we show the Gallionellaceae FeOB genomes encode both characterized iron oxidases as well as uncharacterized multiheme cytochromes (MHCs). MHCs are predicted to transfer electrons from extracellular substrates and likely confer metabolic capabilities that help Gallionellaceae occupy a range of different iron- and mineral-rich niches. Gallionellaceae appear to specialize in iron oxidation, so it would be advantageous for them to have multiple mechanisms to oxidize various forms of iron, given the many iron minerals on Earth, as well as the physiological and kinetic challenges faced by FeOB. The multiple iron/mineral oxidation mechanisms may help drive the widespread ecological success of Gallionellaceae.
Collapse
Affiliation(s)
- Rene L. Hoover
- Microbiology Graduate Program, University of Delaware, Newark, Delaware, USA
- Department of Earth Sciences, University of Delaware, Newark, Delaware, USA
| | - Jessica L. Keffer
- Department of Earth Sciences, University of Delaware, Newark, Delaware, USA
| | - Shawn W. Polson
- Department of Computer and Information Sciences, University of Delaware, Newark, Delaware, USA
- Center for Bioinformatics and Computational Biology, University of Delaware, Newark, Delaware, USA
| | - Clara S. Chan
- Microbiology Graduate Program, University of Delaware, Newark, Delaware, USA
- Department of Earth Sciences, University of Delaware, Newark, Delaware, USA
- School of Marine Science and Policy, University of Delaware, Newark, Delaware, USA
| |
Collapse
|
5
|
Grégoire DS, George NA, Hug LA. Microbial methane cycling in a landfill on a decadal time scale. Nat Commun 2023; 14:7402. [PMID: 37973978 PMCID: PMC10654671 DOI: 10.1038/s41467-023-43129-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 11/01/2023] [Indexed: 11/19/2023] Open
Abstract
Landfills generate outsized environmental footprints due to microbial degradation of organic matter in municipal solid waste, which produces the potent greenhouse gas methane. With global solid waste production predicted to increase substantially in the next few decades, there is a pressing need to better understand the temporal dynamics of biogeochemical processes that control methane cycling in landfills. Here, we use metagenomic approaches to characterize microbial methane cycling in waste that was landfilled over 39 years. Our analyses indicate that newer waste supports more diverse communities with similar composition compared to older waste, which contains lower diversity and more varied communities. Older waste contains primarily autotrophic organisms with versatile redox metabolisms, whereas newer waste is dominated by anaerobic fermenters. Methane-producing microbes are more abundant, diverse, and metabolically versatile in new waste compared to old waste. Our findings indicate that predictive models for methane emission in landfills overlook methane oxidation in the absence of oxygen, as well as certain microbial lineages that can potentially contribute to methane sinks in diverse habitats.
Collapse
Affiliation(s)
- Daniel S Grégoire
- Department of Biology, University of Waterloo, Waterloo, ON, N2L 3G1, Canada.
- Department of Chemistry, Carleton University, Ottawa, ON, K1S 5B6, Canada.
| | - Nikhil A George
- Department of Biology, University of Waterloo, Waterloo, ON, N2L 3G1, Canada
| | - Laura A Hug
- Department of Biology, University of Waterloo, Waterloo, ON, N2L 3G1, Canada.
| |
Collapse
|
6
|
Li L, Liu Z, Meng D, Liu Y, Liu T, Jiang C, Yin H. Sequence similarity network and protein structure prediction offer insights into the evolution of microbial pathways for ferrous iron oxidation. mSystems 2023; 8:e0072023. [PMID: 37768051 PMCID: PMC10654088 DOI: 10.1128/msystems.00720-23] [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: 07/11/2023] [Accepted: 08/09/2023] [Indexed: 09/29/2023] Open
Abstract
IMPORTANCE Microbial Fe(II) oxidation is a crucial process that harnesses and converts the energy available in Fe, contributing significantly to global element cycling. However, there are still many aspects of this process that remain unexplored. In this study, we utilized a combination of comparative genomics, sequence similarity network analysis, and artificial intelligence-driven structure modeling methods to address the lack of structural information on Fe(II) oxidation proteins and offer a comprehensive perspective on the evolution of Fe(II) oxidation pathways. Our findings suggest that several microbial Fe(II) oxidation pathways currently known may have originated within classes Gammaproteobacteria and Betaproteobacteria.
Collapse
Affiliation(s)
- Liangzhi Li
- School of Minerals Processing and Bioengineering, Central South University, Changsha, China
- Key Laboratory of Biometallurgy of Ministry of Education, Central South University, Changsha, China
| | - Zhenghua Liu
- School of Minerals Processing and Bioengineering, Central South University, Changsha, China
- Key Laboratory of Biometallurgy of Ministry of Education, Central South University, Changsha, China
| | - Delong Meng
- School of Minerals Processing and Bioengineering, Central South University, Changsha, China
- Key Laboratory of Biometallurgy of Ministry of Education, Central South University, Changsha, China
| | - Yongjun Liu
- Hunan Tobacco Science Institute, Changsha, China
| | - Tianbo Liu
- Hunan Tobacco Science Institute, Changsha, China
| | - Chengying Jiang
- University of Chinese Academy of Sciences, Beijing, China
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Huaqun Yin
- School of Minerals Processing and Bioengineering, Central South University, Changsha, China
- Key Laboratory of Biometallurgy of Ministry of Education, Central South University, Changsha, China
| |
Collapse
|
7
|
Huang J, Zhao W, Ju J, Liu S, Ye J, Long Y. The existence of ferric hydroxide links the carbon and nitrogen cycles by promoting nitrite-coupled methane anaerobic oxidation. WATER RESEARCH 2023; 243:120192. [PMID: 37454463 DOI: 10.1016/j.watres.2023.120192] [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: 02/22/2023] [Revised: 06/04/2023] [Accepted: 06/06/2023] [Indexed: 07/18/2023]
Abstract
Microorganism-mediated anaerobic oxidation of methane can efficiently mitigate methane atmospheric emissions and is a key process linking the biogeochemical cycles of carbon, nitrogen, and iron. The results showed that methane oxidation and nitrite removal rates in the CF were 1.12 and 1.28 times higher than those in CK, respectively, suggesting that ferric hydroxide can enhance nitrite-driven AOM. The biochemical process was mediated by the enrichment of methanogens, methanotrophs, and denitrifiers. Methanobacterium and Methanosarcina were positively correlated with Fe3+ and Fe2+, whereas Methylocystis and Methylocaldum were positively correlated with methane, and denitrifiers were positively correlated with nitrite. Metagenomic analysis revealed that the genes related to methane oxidation, nitrogen reduction, and heme c-type cytochrome were upregulated in CF, indicating that a synergistic action of bacteria and methanogens drove AOM via diverse metabolic pathways, within which ferric hydroxide played a crucial role. This study provides novel insights into the synergistic mechanism of ferric iron and nitrite-driven AOM.
Collapse
Affiliation(s)
- Juan Huang
- Key Laboratory of Environmental Exposure and Health of Guangdong Province, School of Environment, Jinan University, Guangzhou 510632, China
| | - Wurong Zhao
- Key Laboratory of Environmental Exposure and Health of Guangdong Province, School of Environment, Jinan University, Guangzhou 510632, China
| | - Jinwei Ju
- Key Laboratory of Environmental Exposure and Health of Guangdong Province, School of Environment, Jinan University, Guangzhou 510632, China
| | - Suifen Liu
- Key Laboratory of Environmental Exposure and Health of Guangdong Province, School of Environment, Jinan University, Guangzhou 510632, China
| | - Jinshao Ye
- Key Laboratory of Environmental Exposure and Health of Guangdong Province, School of Environment, Jinan University, Guangzhou 510632, China
| | - Yan Long
- Key Laboratory of Environmental Exposure and Health of Guangdong Province, School of Environment, Jinan University, Guangzhou 510632, China.
| |
Collapse
|
8
|
Bayer T, Tomaszewski EJ, Bryce C, Kappler A, Byrne JM. Continuous cultivation of the lithoautotrophic nitrate-reducing Fe(II)-oxidizing culture KS in a chemostat bioreactor. ENVIRONMENTAL MICROBIOLOGY REPORTS 2023. [PMID: 36992623 DOI: 10.1111/1758-2229.13149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Accepted: 02/15/2023] [Indexed: 06/19/2023]
Abstract
Laboratory-based studies on microbial Fe(II) oxidation are commonly performed for 5-10 days in small volumes with high substrate concentrations, resulting in geochemical gradients and volumetric effects caused by sampling. We used a chemostat to enable uninterrupted supply of medium and investigated autotrophic nitrate-reducing Fe(II)-oxidizing culture KS for 24 days. We analysed Fe- and N-speciation, cell-mineral associations, and the identity of minerals. Results were compared to batch systems (50 and 700 mL-static/shaken). The Fe(II) oxidation rate was highest in the chemostat with 7.57 mM Fe(II) d-1 , while the extent of oxidation was similar to the other experimental setups (average oxidation of 92% of all Fe(II)). Short-range ordered Fe(III) phases, presumably ferrihydrite, precipitated and later goethite was detected in the chemostat. The 1 mM solid phase Fe(II) remained in the chemostat, up to 15 μM of reactive nitrite was measured, and 42% of visualized cells were partially or completely mineral-encrusted, likely caused by abiotic oxidation of Fe(II) by nitrite. Despite (partial) encrustation, cells were still viable. Our results show that even with similar oxidation rates as in batch cultures, cultivating Fe(II)-oxidizing microorganisms under continuous conditions reveals the importance of reactive nitrogen intermediates on Fe(II) oxidation, mineral formation and cell-mineral interactions.
Collapse
Affiliation(s)
- Timm Bayer
- Geomicrobiology Group, Center for Applied Geoscience, University of Tuebingen, Tuebingen, Germany
| | - Elizabeth J Tomaszewski
- Geomicrobiology Group, Center for Applied Geoscience, University of Tuebingen, Tuebingen, Germany
| | - Casey Bryce
- School of Earth Sciences, University of Bristol, Bristol, UK
| | - Andreas Kappler
- Geomicrobiology Group, Center for Applied Geoscience, University of Tuebingen, Tuebingen, Germany
- Cluster of Excellence: EXC 2124: Controlling Microbes to Fight Infection, Tuebingen, Germany
| | - James M Byrne
- School of Earth Sciences, University of Bristol, Bristol, UK
| |
Collapse
|
9
|
Huang J, Mellage A, Garcia JP, Glöckler D, Mahler S, Elsner M, Jakus N, Mansor M, Jiang H, Kappler A. Metabolic Performance and Fate of Electrons during Nitrate-Reducing Fe(II) Oxidation by the Autotrophic Enrichment Culture KS Grown at Different Initial Fe/N Ratios. Appl Environ Microbiol 2023; 89:e0019623. [PMID: 36877057 PMCID: PMC10057050 DOI: 10.1128/aem.00196-23] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Accepted: 02/11/2023] [Indexed: 03/07/2023] Open
Abstract
Autotrophic nitrate-reducing Fe(II)-oxidizing (NRFeOx) microorganisms fix CO2 and oxidize Fe(II) coupled to denitrification, influencing carbon, iron, and nitrogen cycles in pH-neutral, anoxic environments. However, the distribution of electrons from Fe(II) oxidation to either biomass production (CO2 fixation) or energy generation (nitrate reduction) in autotrophic NRFeOx microorganisms has not been quantified. We therefore cultivated the autotrophic NRFeOx culture KS at different initial Fe/N ratios, followed geochemical parameters, identified minerals, analyzed N isotopes, and applied numerical modeling. We found that at all initial Fe/N ratios, the ratios of Fe(II)oxidized to nitratereduced were slightly higher (5.11 to 5.94 at Fe/N ratios of 10:1 and 10:0.5) or lower (4.27 to 4.59 at Fe/N ratios of 10:4, 10:2, 5:2, and 5:1) than the theoretical ratio for 100% Fe(II) oxidation being coupled to nitrate reduction (5:1). The main N denitrification product was N2O (71.88 to 96.29% at Fe/15N ratios of 10:4 and 5:1; 43.13 to 66.26% at an Fe/15N ratio of 10:1), implying that denitrification during NRFeOx was incomplete in culture KS. Based on the reaction model, on average 12% of electrons from Fe(II) oxidation were used for CO2 fixation while 88% of electrons were used for reduction of NO3- to N2O at Fe/N ratios of 10:4, 10:2, 5:2, and 5:1. With 10 mM Fe(II) (and 4, 2, 1, or 0.5 mM nitrate), most cells were closely associated with and partially encrusted by the Fe(III) (oxyhydr)oxide minerals, whereas at 5 mM Fe(II), most cells were free of cell surface mineral precipitates. The genus Gallionella (>80%) dominated culture KS regardless of the initial Fe/N ratios. Our results showed that Fe/N ratios play a key role in regulating N2O emissions, for distributing electrons between nitrate reduction and CO2 fixation, and for the degree of cell-mineral interactions in the autotrophic NRFeOx culture KS. IMPORTANCE Autotrophic NRFeOx microorganisms that oxidize Fe(II), reduce nitrate, and produce biomass play a key role in carbon, iron, and nitrogen cycles in pH-neutral, anoxic environments. Electrons from Fe(II) oxidation are used for the reduction of both carbon dioxide and nitrate. However, the question is how many electrons go into biomass production versus energy generation during autotrophic growth. Here, we demonstrated that in the autotrophic NRFeOx culture KS cultivated at Fe/N ratios of 10:4, 10:2, 5:2, and 5:1, ca. 12% of electrons went into biomass formation, while 88% of electrons were used for reduction of NO3- to N2O. Isotope analysis also showed that denitrification during NRFeOx was incomplete in culture KS and the main N denitrification product was N2O. Therefore, most electrons stemming from Fe(II) oxidation seemed to be used for N2O formation in culture KS. This is environmentally important for the greenhouse gas budget.
Collapse
Affiliation(s)
- Jianrong Huang
- Geomicrobiology, Department of Geoscience, University of Tuebingen, Tuebingen, Germany
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, China
| | - Adrian Mellage
- Hydrogeology, Civil and Environmental Engineering, University of Kassel, Kassel, Germany
- Hydrogeology, Department of Geosciences, University of Tuebingen, Tuebingen, Germany
| | - Julian Pavon Garcia
- Hydrogeology, Department of Geosciences, University of Tuebingen, Tuebingen, Germany
| | - David Glöckler
- Analytical Chemistry and Water Chemistry, Technical University of Munich, Munich, Germany
| | - Susanne Mahler
- Analytical Chemistry and Water Chemistry, Technical University of Munich, Munich, Germany
| | - Martin Elsner
- Analytical Chemistry and Water Chemistry, Technical University of Munich, Munich, Germany
| | - Natalia Jakus
- Geomicrobiology, Department of Geoscience, University of Tuebingen, Tuebingen, Germany
- School of Architecture, Civil and Environmental Engineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Muammar Mansor
- Geomicrobiology, Department of Geoscience, University of Tuebingen, Tuebingen, Germany
| | - Hongchen Jiang
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, China
| | - Andreas Kappler
- Geomicrobiology, Department of Geoscience, University of Tuebingen, Tuebingen, Germany
- Cluster of Excellence, EXC 2124, Controlling Microbes to Fight Infection, Tuebingen, Germany
| |
Collapse
|
10
|
Wang Y, Ren S, Wang P, Wang B, Hu K, Li J, Wang Y, Li Z, Li S, Li W, Peng Y. Autotrophic denitrification using Fe(II) as an electron donor: A novel prospective denitrification process. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 858:159721. [PMID: 36306837 DOI: 10.1016/j.scitotenv.2022.159721] [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: 09/05/2022] [Revised: 10/21/2022] [Accepted: 10/21/2022] [Indexed: 06/16/2023]
Abstract
As a newly identified nitrogen loss pathway, the nitrate-dependent ferrous oxidation (NDFO) process is emerging as a research hotspot in the field of low carbon to nitrogen ratio (C/N) wastewater treatment. This review article provides an overview of the NDFO process and summarizes the functional microorganisms associated with NDFO from different perspectives. The potential mechanisms by which external factors such as influent pH, influent Fe(II)/N (mol), organic carbon, and chelating agents affect NDFO performance are also thoroughly discussed. As the electron-transfer mechanism of the NDFO process is still largely unknown, the extensive chemical Fe(II)-oxidizing nitrite-reducing pathway (NDFOchem) of the NDFO process is described here, and the potential enzymatic electron transfer mechanisms involved are summarized. On this basis, a three-stage electron transfer pathway applicable to low C/N wastewater is proposed. Furthermore, the impact of Fe(III) mineral products on the NDFO process is revisited, and existing crusting prevention strategies are summarized. Finally, future challenges facing the NDFO process and new research directions are discussed, with the aim of further promoting the development and application of the NDFO process in the field of nitrogen removal.
Collapse
Affiliation(s)
- Yaning Wang
- College of Environmental and Municipal Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China; Key laboratory of Yellow River Water Environment in Gansu Province, Lanzhou 730070, China
| | - Shuang Ren
- College of Environmental and Municipal Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China; Key laboratory of Yellow River Water Environment in Gansu Province, Lanzhou 730070, China
| | - Peng Wang
- College of Environmental and Municipal Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China; Key laboratory of Yellow River Water Environment in Gansu Province, Lanzhou 730070, China.
| | - Bo Wang
- School of Geosciences, China University of Petroleum, Qingdao 266580, China
| | - Kaiyao Hu
- College of Environmental and Municipal Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China; Key laboratory of Yellow River Water Environment in Gansu Province, Lanzhou 730070, China
| | - Jie Li
- College of Environmental and Municipal Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China; Key laboratory of Yellow River Water Environment in Gansu Province, Lanzhou 730070, China; Gansu membrane science and technology research institute Co.,Ltd., Lanzhou 730020, China; Key Laboratory for Resources Utilization Technology of Unconventional Water of Gansu Province, Lanzhou 730020, China
| | - Yae Wang
- College of Environmental and Municipal Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China; Key laboratory of Yellow River Water Environment in Gansu Province, Lanzhou 730070, China
| | - Zongxing Li
- Key Laboratory of Ecohydrology of Inland River Basin/Gansu Qilian Mountains Ecology Research Center, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China
| | - Sumei Li
- College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China
| | - Wang Li
- Taiyuan university of technology, Taiyuan 030024, China; State Key Laboratory of Clean and Efficient Coal Utilization, Taiyuan 030024, China
| | - Yuzhuo Peng
- College of Environmental and Municipal Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China; Key laboratory of Yellow River Water Environment in Gansu Province, Lanzhou 730070, China
| |
Collapse
|
11
|
Salinity Impact on Composition and Activity of Nitrate-Reducing Fe(II)-Oxidizing Microorganisms in Saline Lakes. Appl Environ Microbiol 2022; 88:e0013222. [PMID: 35499328 DOI: 10.1128/aem.00132-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Nitrate-reducing Fe(II)-oxidizing (NRFeOx) microorganisms contribute to nitrogen, carbon, and iron cycling in freshwater and marine ecosystems. However, NRFeOx microorganisms have not been investigated in hypersaline lakes, and their identity, as well as their activity in response to salinity, is unknown. In this study, we combined cultivation-based most probable number (MPN) counts with Illumina MiSeq sequencing to analyze the abundance and community compositions of NRFeOx microorganisms enriched from five lake sediments with different salinities (ranging from 0.67 g/L to 346 g/L). MPN results showed that the abundance of NRFeOx microorganisms significantly (P < 0.05) decreased with increasing lake salinity, from 7.55 × 103 to 8.09 cells/g dry sediment. The community composition of the NRFeOx enrichment cultures obtained from the MPNs differed distinctly among the five lakes and clustered with lake salinity. Two stable enrichment cultures, named FeN-EHL and FeN-CKL, were obtained from microcosm incubations of sediment from freshwater Lake Erhai and hypersaline Lake Chaka. The culture FeN-EHL was dominated by genus Gallionella (68.4%), while the culture FeN-CKL was dominated by genus Marinobacter (71.2%), with the former growing autotrophically and the latter requiring an additional organic substrate (acetate) and Fe(II) oxidation, caused to a large extent by chemodenitrification [reaction of nitrite with Fe(II)]. Short-range ordered Fe(III) (oxyhydr)oxides were the product of Fe(II) oxidation, and the cells were partially attached to or encrusted by the formed iron minerals in both cultures. In summary, different types of interactions between Fe(II) and nitrate-reducing bacteria may exist in freshwater and hypersaline lakes, i.e., autotrophic NRFeOx and chemodenitrification in freshwater and hypersaline environments, respectively. IMPORTANCE NRFeOx microorganisms are globally distributed in various types of environments and play a vital role in iron transformation and nitrate and heavy metal removal. However, most known NRFeOx microorganisms were isolated from freshwater and marine environments, while their identity and activity under hypersaline conditions remain unknown. Here, we demonstrated that salinity may affect the abundance, identity, and nutrition modes of NRFeOx microorganisms. Autotrophy was only detectable in a freshwater lake but not in the saline lake investigated. We enriched a mixotrophic culture capable of nitrate-reducing Fe(II) oxidation from hypersaline lake sediments. However, Fe(II) oxidation was probably caused by abiotic nitrite reduction (chemodenitrification) rather than by a biologically mediated process. Consequently, our study suggests that in hypersaline environments, Fe(II) oxidation is largely caused by chemodentrification initiated by nitrite formation by chemoheterotrophic bacteria, and additional experiments are needed to demonstrate whether or to what extent Fe(II) is enzymatically oxidized.
Collapse
|
12
|
Krakau S, Straub D, Gourlé H, Gabernet G, Nahnsen S. nf-core/mag: a best-practice pipeline for metagenome hybrid assembly and binning. NAR Genom Bioinform 2022; 4:lqac007. [PMID: 35118380 PMCID: PMC8808542 DOI: 10.1093/nargab/lqac007] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 11/19/2021] [Accepted: 01/25/2022] [Indexed: 12/18/2022] Open
Abstract
The analysis of shotgun metagenomic data provides valuable insights into microbial communities, while allowing resolution at individual genome level. In absence of complete reference genomes, this requires the reconstruction of metagenome assembled genomes (MAGs) from sequencing reads. We present the nf-core/mag pipeline for metagenome assembly, binning and taxonomic classification. It can optionally combine short and long reads to increase assembly continuity and utilize sample-wise group-information for co-assembly and genome binning. The pipeline is easy to install-all dependencies are provided within containers-portable and reproducible. It is written in Nextflow and developed as part of the nf-core initiative for best-practice pipeline development. All codes are hosted on GitHub under the nf-core organization https://github.com/nf-core/mag and released under the MIT license.
Collapse
Affiliation(s)
- Sabrina Krakau
- Quantitative Biology Center (QBiC), University of Tübingen, 72076 Tübingen, Germany
| | - Daniel Straub
- Quantitative Biology Center (QBiC), University of Tübingen, 72076 Tübingen, Germany
| | - Hadrien Gourlé
- Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, S-75007 Uppsala, Sweden
| | - Gisela Gabernet
- Quantitative Biology Center (QBiC), University of Tübingen, 72076 Tübingen, Germany
| | - Sven Nahnsen
- Quantitative Biology Center (QBiC), University of Tübingen, 72076 Tübingen, Germany
| |
Collapse
|
13
|
‘Candidatus ferrigenium straubiae’ sp. nov., ‘Candidatus ferrigenium bremense’ sp. nov., ‘Candidatus ferrigenium altingense’ sp. nov., are autotrophic Fe(II)-oxidizing bacteria of the family Gallionellaceae. Syst Appl Microbiol 2022; 45:126306. [DOI: 10.1016/j.syapm.2022.126306] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 02/06/2022] [Accepted: 02/07/2022] [Indexed: 01/04/2023]
|
14
|
Dopffel N, Jamieson J, Bryce C, Joshi P, Mansor M, Siade A, Prommer H, Kappler A. Temperature dependence of nitrate-reducing Fe(II) oxidation by Acidovorax strain BoFeN1 - evaluating the role of enzymatic vs. abiotic Fe(II) oxidation by nitrite. FEMS Microbiol Ecol 2021; 97:6442174. [PMID: 34849752 DOI: 10.1093/femsec/fiab155] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Accepted: 11/24/2021] [Indexed: 11/14/2022] Open
Abstract
Fe(II) oxidation coupled to nitrate reduction is a widely observed metabolism. However, to what extent the observed Fe(II) oxidation is driven enzymatically or abiotically by metabolically produced nitrite remains puzzling. To distinguish between biotic and abiotic reactions, we cultivated the mixotrophic nitrate-reducing Fe(II)-oxidizing Acidovorax strain BoFeN1 over a wide range of temperatures and compared it to abiotic Fe(II) oxidation by nitrite at temperatures up to 60°C. The collected experimental data were subsequently analyzed through biogeochemical modeling. At 5°C, BoFeN1 cultures consumed acetate and reduced nitrate but did not significantly oxidize Fe(II). Abiotic Fe(II) oxidation by nitrite at different temperatures showed an Arrhenius-type behavior with an activation energy of 80±7 kJ/mol. Above 40°C, the kinetics of Fe(II) oxidation were abiotically driven, whereas at 30°C, where BoFeN1 can actively metabolize, the model-based interpretation strongly suggested that an enzymatic pathway was responsible for a large fraction (ca. 62%) of the oxidation. This result was reproduced even when no additional carbon source was present. Our results show that at below 30°C, i.e., at temperatures representing most natural environments, biological Fe(II) oxidation was largely responsible for overall Fe(II) oxidation, while abiotic Fe(II) oxidation by nitrite played a less important role.
Collapse
Affiliation(s)
- Nicole Dopffel
- Norwegian Research Center - NORCE, 22 Nygårdstangen, 5838 Bergen, Norway
- Geomicrobiology, Center for Applied Geosciences, University of Tübingen, 72074 Tübingen, Germany
| | - James Jamieson
- School of Earth Sciences, University of Western Australia, 35 Stirling Highway, 6009 Crawley, Australia
- CSIRO Land and Water, 147 Underwood Avenue, 6014 Floreat, Australia
| | - Casey Bryce
- School of Earth Sciences, University of Bristol, Queens Road, Bristol BS8 1RJ, United Kingdom
| | - Prachi Joshi
- Geomicrobiology, Center for Applied Geosciences, University of Tübingen, 72074 Tübingen, Germany
| | - Muammar Mansor
- Geomicrobiology, Center for Applied Geosciences, University of Tübingen, 72074 Tübingen, Germany
| | - Adam Siade
- School of Earth Sciences, University of Western Australia, 35 Stirling Highway, 6009 Crawley, Australia
- CSIRO Land and Water, 147 Underwood Avenue, 6014 Floreat, Australia
| | - Henning Prommer
- School of Earth Sciences, University of Western Australia, 35 Stirling Highway, 6009 Crawley, Australia
- CSIRO Land and Water, 147 Underwood Avenue, 6014 Floreat, Australia
| | - Andreas Kappler
- Geomicrobiology, Center for Applied Geosciences, University of Tübingen, 72074 Tübingen, Germany
- Cluster of Excellence EXC 2124: Controlling Microbes to Fight Infection, University of Tubingen, 72074 Tübingen, Germany
| |
Collapse
|
15
|
Nitrate Removal by a Novel Lithoautotrophic Nitrate-Reducing, Iron(II)-Oxidizing Culture Enriched from a Pyrite-Rich Limestone Aquifer. Appl Environ Microbiol 2021; 87:e0046021. [PMID: 34085863 DOI: 10.1128/aem.00460-21] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Nitrate removal in oligotrophic environments is often limited by the availability of suitable organic electron donors. Chemolithoautotrophic bacteria may play a key role in denitrification in aquifers depleted in organic carbon. Under anoxic and circumneutral pH conditions, iron(II) was hypothesized to serve as an electron donor for microbially mediated nitrate reduction by Fe(II)-oxidizing (NRFeOx) microorganisms. However, lithoautotrophic NRFeOx cultures have never been enriched from any aquifer, and as such, there are no model cultures available to study the physiology and geochemistry of this potentially environmentally relevant process. Using iron(II) as an electron donor, we enriched a lithoautotrophic NRFeOx culture from nitrate-containing groundwater of a pyrite-rich limestone aquifer. In the enriched NRFeOx culture that does not require additional organic cosubstrates for growth, within 7 to 11 days, 0.3 to 0.5 mM nitrate was reduced and 1.3 to 2 mM iron(II) was oxidized, leading to a stoichiometric NO3-/Fe(II) ratio of 0.2, with N2 and N2O identified as the main nitrate reduction products. Short-range ordered Fe(III) (oxyhydr)oxides were the product of iron(II) oxidation. Microorganisms were observed to be closely associated with formed minerals, but only few cells were encrusted, suggesting that most of the bacteria were able to avoid mineral precipitation at their surface. Analysis of the microbial community by long-read 16S rRNA gene sequencing revealed that the culture is dominated by members of the Gallionellaceae family that are known as autotrophic, neutrophilic, and microaerophilic iron(II) oxidizers. In summary, our study suggests that NRFeOx mediated by lithoautotrophic bacteria can lead to nitrate removal in anthropogenically affected aquifers. IMPORTANCE Removal of nitrate by microbial denitrification in groundwater is often limited by low concentrations of organic carbon. In these carbon-poor ecosystems, nitrate-reducing bacteria that can use inorganic compounds such as Fe(II) (NRFeOx) as electron donors could play a major role in nitrate removal. However, no lithoautotrophic NRFeOx culture has been successfully isolated or enriched from this type of environment, and as such, there are no model cultures available to study the rate-limiting factors of this potentially important process. Here, we present the physiology and microbial community composition of a novel lithoautotrophic NRFeOx culture enriched from a fractured aquifer in southern Germany. The culture is dominated by a putative Fe(II) oxidizer affiliated with the Gallionellaceae family and performs nitrate reduction coupled to Fe(II) oxidation leading to N2O and N2 formation without the addition of organic substrates. Our analyses demonstrate that lithoautotrophic NRFeOx can potentially lead to nitrate removal in nitrate-contaminated aquifers.
Collapse
|
16
|
Huang YM, Straub D, Blackwell N, Kappler A, Kleindienst S. Meta-omics Reveal Gallionellaceae and Rhodanobacter Species as Interdependent Key Players for Fe(II) Oxidation and Nitrate Reduction in the Autotrophic Enrichment Culture KS. Appl Environ Microbiol 2021; 87:e0049621. [PMID: 34020935 PMCID: PMC8276803 DOI: 10.1128/aem.00496-21] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Accepted: 05/16/2021] [Indexed: 01/04/2023] Open
Abstract
Nitrate reduction coupled to Fe(II) oxidation (NRFO) has been recognized as an environmentally important microbial process in many freshwater ecosystems. However, well-characterized examples of autotrophic nitrate-reducing Fe(II)-oxidizing bacteria are rare, and their pathway of electron transfer as well as their interaction with flanking community members remain largely unknown. Here, we applied meta-omics (i.e., metagenomics, metatranscriptomics, and metaproteomics) to the nitrate-reducing Fe(II)-oxidizing enrichment culture KS growing under autotrophic or heterotrophic conditions and originating from freshwater sediment. We constructed four metagenome-assembled genomes with an estimated completeness of ≥95%, including the key players of NRFO in culture KS, identified as Gallionellaceae sp. and Rhodanobacter sp. The Gallionellaceae sp. and Rhodanobacter sp. transcripts and proteins likely involved in Fe(II) oxidation (e.g., mtoAB, cyc2, and mofA), denitrification (e.g., napGHI), and oxidative phosphorylation (e.g., respiratory chain complexes I to V) along with Gallionellaceae sp. transcripts and proteins for carbon fixation (e.g., rbcL) were detected. Overall, our results indicate that in culture KS, the Gallionellaceae sp. and Rhodanobacter sp. are interdependent: while Gallionellaceae sp. fixes CO2 and provides organic compounds for Rhodanobacter sp., Rhodanobacter sp. likely detoxifies NO through NO reduction and completes denitrification, which cannot be performed by Gallionellaceae sp. alone. Additionally, the transcripts and partial proteins of cbb3- and aa3-type cytochrome c suggest the possibility for a microaerophilic lifestyle of the Gallionellaceae sp., yet culture KS grows under anoxic conditions. Our findings demonstrate that autotrophic NRFO is performed through cooperation among denitrifying and Fe(II)-oxidizing bacteria, which might resemble microbial interactions in freshwater environments. IMPORTANCE Nitrate-reducing Fe(II)-oxidizing bacteria are widespread in the environment, contribute to nitrate removal, and influence the fate of the greenhouse gases nitrous oxide and carbon dioxide. The autotrophic growth of nitrate-reducing Fe(II)-oxidizing bacteria is rarely investigated and not fully understood. The most prominent model system for this type of study is the enrichment culture KS. To gain insights into the metabolism of nitrate reduction coupled to Fe(II) oxidation in the absence of organic carbon and oxygen, we performed metagenomic, metatranscriptomic, and metaproteomic analyses of culture KS and identified Gallionellaceae sp. and Rhodanobacter sp. as interdependent key Fe(II) oxidizers in culture KS. Our work demonstrates that autotrophic nitrate reduction coupled to Fe(II) oxidation is not performed by an individual strain but is a cooperation of at least two members of the bacterial community in culture KS. These findings serve as a foundation for our understanding of nitrate-reducing Fe(II)-oxidizing bacteria in the environment.
Collapse
Affiliation(s)
- Yu-Ming Huang
- Microbial Ecology, Center for Applied Geoscience, University of Tübingen, Tübingen, Germany
- Geomicrobiology, Center for Applied Geoscience, University of Tübingen, Tübingen, Germany
| | - Daniel Straub
- Microbial Ecology, Center for Applied Geoscience, University of Tübingen, Tübingen, Germany
- Quantitative Biology Center (QBiC), University of Tübingen, Tübingen, Germany
| | - Nia Blackwell
- Microbial Ecology, Center for Applied Geoscience, University of Tübingen, Tübingen, Germany
| | - Andreas Kappler
- Geomicrobiology, Center for Applied Geoscience, University of Tübingen, Tübingen, Germany
- Cluster of Excellence, EXC 2124, “Controlling Microbes to Fight Infections,” University of Tübingen, Tübingen, Germany
| | - Sara Kleindienst
- Microbial Ecology, Center for Applied Geoscience, University of Tübingen, Tübingen, Germany
| |
Collapse
|