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Trinh HP, Lee SH, Kim NK, Nguyen TV, Park HD. Fimbriimonadales performed dissimilatory nitrate reduction to ammonium (DNRA) in an anammox reactor. WATER RESEARCH 2024; 268:122575. [PMID: 39383805 DOI: 10.1016/j.watres.2024.122575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2024] [Revised: 09/23/2024] [Accepted: 10/02/2024] [Indexed: 10/11/2024]
Abstract
Bacteria belonging to the order Fimbriimonadales are frequently detected in anammox reactors. However, the principal functions of these bacteria and their potential contribution to nitrogen removal remain unclear. In this study, we aimed to systematically validate the roles of Fimbriimonadales in an anammox reactor fed with synthetic wastewater. High-throughput 16S rRNA gene sequencing analysis revealed that heterotrophic denitrifying bacteria (HDB) were the most abundant bacterial group at the initial stage of reactor operation and the abundance of Fimbriimonadales members gradually increased to reach 38.8 % (day 196). At the end of reactor operation, Fimbriimonadales decreased to 0.9 % with an increase in anammox bacteria. Correlation analysis demonstrated nitrate competition between Fimbriimonadales and HDB during reactor operation. Based on the phylogenetic analysis, the Fimbriimonadales sequences acquired from the reactor were clustered into three distinct groups, which included the sequences obtained from other anammox reactors. Metagenome-assembled genome analysis of Fimbriimonadales allowed the identification of the genes narGHI and nrfAH, responsible for dissimilatory nitrate reduction to ammonium (DNRA), and nrt and nasA, responsible for nitrate and nitrite transport. In a simulation based on mass balance equations and quantified bacterial groups, the total nitrogen concentrations in the effluent were best predicted when Fimbriimonadales was assumed to perform DNRA (R2 = 0.70 and RMSE = 18.9). Moreover, mass balance analysis demonstrated the potential contribution of DNRA in enriching anammox bacteria and promoting nitrogen removal. These results prove that Fimbriimonadales compete with HDB for nitrate utilization through DNRA in the anammox reactor under non-exogenous carbon supply conditions. Overall, our findings suggest that the DNRA pathway in Fimbriimonadales could enhance anammox enrichment and nitrogen removal by providing substrates (nitrite and/or ammonium) for anammox bacteria.
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Affiliation(s)
- Hoang Phuc Trinh
- School of Civil, Environmental and Architectural Engineering, Korea University, Seoul 02841, South Korea
| | - Sang-Hoon Lee
- School of Civil, Environmental and Architectural Engineering, Korea University, Seoul 02841, South Korea
| | - Na-Kyung Kim
- Department of Animal Science, College of Agricultural, Consumer, and Environmental Science, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Thi Vinh Nguyen
- School of Civil, Environmental and Architectural Engineering, Korea University, Seoul 02841, South Korea
| | - Hee-Deung Park
- School of Civil, Environmental and Architectural Engineering, Korea University, Seoul 02841, South Korea; KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, South Korea.
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Cerda Á, Rodríguez C, González M, González H, Serrano J, Leiva E. Feammox bacterial biofilm formation in HFMB. CHEMOSPHERE 2024; 358:142072. [PMID: 38657691 DOI: 10.1016/j.chemosphere.2024.142072] [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: 11/16/2023] [Revised: 04/08/2024] [Accepted: 04/16/2024] [Indexed: 04/26/2024]
Abstract
Nitrogen pollution has been increasing with the development of industrialization. Consequently, the excessive deposition of reactive nitrogen in the environment has generated the loss of biodiversity and eutrophication of different ecosystems. In 2005, a Feammox process was discovered that anaerobically metabolizes ammonium. Feammox with the use of hollow fiber membrane bioreactors (HFMB), based on the formation of biofilms of bacterial communities, has emerged as a possible efficient and sustainable method for ammonium removal in environments with high iron concentrations. This work sought to study the possibility of implementing, at laboratory scale, an efficient method by evaluating the use of HFMB. Samples from an internal circulation reactor (IC) incubated in culture media for Feammox bacteria. The cultures were enriched in a batch reactor to evaluate growth conditions. Next, HFMB assembly was performed, and Feammox parameters were monitored. Also, conventional PCR and scanning electron microscopy (SEM) analysis were performed to characterize the bacterial communities associated with biofilm formation. The use of sodium acetate presented the best performance for Feammox activity. The HFMB operation showed an ammonium (NH4+) removal of 50%. SEM analysis of the fibers illustrated the formation of biofilm networks formed by bacteria, which were identified as Albidiferax ferrireducens, Geobacter spp, Ferrovum myxofaciens, Shewanella spp., and Anammox. Functional genes Archaea/Bacteria ammonia monooxygenase, nrxA, hzsB, nirS and nosZ were also identified. The implementation of HFMB Feammox could be used as a sustainable tool for the removal of ammonium from wastewater produced because of anthropogenic activities.
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Affiliation(s)
- Ámbar Cerda
- Departamento de Química Inorgánica, Facultad de Química y de Farmacia, Pontificia Universidad Católica de Chile, Avenida Vicuña Mackenna 4860, Macul, 7820436, Santiago, Chile.
| | - Carolina Rodríguez
- Departamento de Química Inorgánica, Facultad de Química y de Farmacia, Pontificia Universidad Católica de Chile, Avenida Vicuña Mackenna 4860, Macul, 7820436, Santiago, Chile.
| | - Macarena González
- Departamento de Química Inorgánica, Facultad de Química y de Farmacia, Pontificia Universidad Católica de Chile, Avenida Vicuña Mackenna 4860, Macul, 7820436, Santiago, Chile.
| | - Heylin González
- Departamento de Ingeniería Hidráulica y Ambiental, Pontificia Universidad Católica de Chile, Avenida Vicuña Mackenna 4860, Macul, 7820436, Santiago, Chile.
| | - Jennyfer Serrano
- Escuela de Biotecnología, Universidad Mayor, Camino La Pirámide 5750, Huechuraba, Santiago 8580745, Chile.
| | - Eduardo Leiva
- Departamento de Química Inorgánica, Facultad de Química y de Farmacia, Pontificia Universidad Católica de Chile, Avenida Vicuña Mackenna 4860, Macul, 7820436, Santiago, Chile; Departamento de Ingeniería Hidráulica y Ambiental, Pontificia Universidad Católica de Chile, Avenida Vicuña Mackenna 4860, Macul, 7820436, Santiago, Chile.
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Bell E, Chen J, Richardson WDL, Fustic M, Hubert CRJ. Denitrification genotypes of endospore-forming Bacillota. ISME COMMUNICATIONS 2024; 4:ycae107. [PMID: 39263550 PMCID: PMC11388526 DOI: 10.1093/ismeco/ycae107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2024] [Revised: 08/14/2024] [Accepted: 08/19/2024] [Indexed: 09/13/2024]
Abstract
Denitrification is a key metabolic process in the global nitrogen cycle and is performed by taxonomically diverse microorganisms. Despite the widespread importance of this metabolism, challenges remain in identifying denitrifying populations and predicting their metabolic end-products based on their genotype. Here, genome-resolved metagenomics was used to explore the denitrification genotype of Bacillota enriched in nitrate-amended high temperature incubations with confirmed N2O and N2 production. A set of 12 hidden Markov models (HMMs) was created to target the diversity of denitrification genes in members of the phylum Bacillota. Genomic potential for complete denitrification was found in five metagenome-assembled genomes from nitrate-amended enrichments, including two novel members of the Brevibacillaceae family. Genomes of complete denitrifiers encode N2O reductase gene clusters with clade II-type nosZ and often include multiple variants of the nitric oxide reductase gene. The HMM set applied to all genomes of Bacillota from the Genome Taxonomy Database identified 17 genera inferred to contain complete denitrifiers based on their gene content. Among complete denitrifiers it was common for three distinct nitric oxide reductases to be present (qNOR, bNOR, and sNOR) that may reflect the metabolic adaptability of Bacillota in environments with variable redox conditions.
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Affiliation(s)
- Emma Bell
- Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
| | - Jianwei Chen
- Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
| | - William D L Richardson
- Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
| | - Milovan Fustic
- Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
- Department of Geology, Nazarbayev University, 53 Kabanbay Batyr Ave, Astana 010000, Kazakhstan
| | - Casey R J Hubert
- Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
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Hung SHW, Yeh PH, Huang TC, Huang SY, Wu IC, Liu CH, Lin YH, Chien PR, Huang FC, Ho YN, Kuo CH, Hwang HH, Chiang EPI, Huang CC. A cyclic dipeptide for salinity stress alleviation and the trophic flexibility of endophyte provide insights into saltmarsh plant-microbe interactions. ISME COMMUNICATIONS 2024; 4:ycae041. [PMID: 38707842 PMCID: PMC11070113 DOI: 10.1093/ismeco/ycae041] [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: 12/19/2023] [Revised: 02/23/2024] [Accepted: 03/20/2024] [Indexed: 05/07/2024]
Abstract
In response to climate change, the nature of endophytes and their applications in sustainable agriculture have attracted the attention of academics and agro-industries. This work focused on the endophytic halophiles of the endangered Taiwanese salt marsh plant, Bolboschoenus planiculmis, and evaluated the functions of these isolates through in planta salinity stress alleviation assay using Arabidopsis. The endophytic strain Priestia megaterium BP01R2, which can promote plant growth and salinity tolerance, was further characterized through multi-omics approaches. The transcriptomics results suggested that BP01R2 could function by tuning hormone signal transduction, energy-producing metabolism, multiple stress responses, etc. In addition, the cyclodipeptide cyclo(L-Ala-Gly), which was identified by metabolomics analysis, was confirmed to contribute to the alleviation of salinity stress in stressed plants via exogenous supplementation. In this study, we used multi-omics approaches to investigate the genomics, metabolomics, and tropisms of endophytes, as well as the transcriptomics of plants in response to the endophyte. The results revealed the potential molecular mechanisms underlying the occurrence of biostimulant-based plant-endophyte symbioses with possible application in sustainable agriculture.
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Affiliation(s)
- Shih-Hsun Walter Hung
- Department of Life Sciences, National Chung Hsing University, Taichung 402202, Taiwan
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 115201, Taiwan
- Advanced Plant and Food Crop Biotechnology Center, National Chung Hsing University, Taichung 402202, Taiwan
| | - Pin-Hsien Yeh
- Department of Life Sciences, National Chung Hsing University, Taichung 402202, Taiwan
| | - Tsai-Ching Huang
- Department of Life Sciences, National Chung Hsing University, Taichung 402202, Taiwan
| | - Shao-Yu Huang
- Department of Life Sciences, National Chung Hsing University, Taichung 402202, Taiwan
| | - I-Chen Wu
- Department of Life Sciences, National Chung Hsing University, Taichung 402202, Taiwan
| | - Chia-Ho Liu
- Department of Life Sciences, National Chung Hsing University, Taichung 402202, Taiwan
| | - Yu-Hsi Lin
- Department of Life Sciences, National Chung Hsing University, Taichung 402202, Taiwan
| | - Pei-Ru Chien
- Department of Life Sciences, National Chung Hsing University, Taichung 402202, Taiwan
| | - Fan-Chen Huang
- Department of Life Sciences, National Chung Hsing University, Taichung 402202, Taiwan
| | - Ying-Ning Ho
- Institute of Marine Biology, College of Life Science, National Taiwan Ocean University, Keelung 202301, Taiwan
- Centre of Excellence for the Oceans, National Taiwan Ocean University, Keelung 202301, Taiwan
- Taiwan Ocean Genome Center, National Taiwan Ocean University, Keelung 202301, Taiwan
| | - Chih-Horng Kuo
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 115201, Taiwan
- Biotechnology Center, National Chung Hsing University, Taichung 402202, Taiwan
| | - Hau-Hsuan Hwang
- Department of Life Sciences, National Chung Hsing University, Taichung 402202, Taiwan
- Advanced Plant and Food Crop Biotechnology Center, National Chung Hsing University, Taichung 402202, Taiwan
- Innovation and Development Center of Sustainable Agriculture, National Chung Hsing University, Taichung 402202, Taiwan
| | - En-Pei Isabel Chiang
- Advanced Plant and Food Crop Biotechnology Center, National Chung Hsing University, Taichung 402202, Taiwan
- Innovation and Development Center of Sustainable Agriculture, National Chung Hsing University, Taichung 402202, Taiwan
- Department of Food Science and Biotechnology, National Chung Hsing University, Taichung 402202, Taiwan
| | - Chieh-Chen Huang
- Department of Life Sciences, National Chung Hsing University, Taichung 402202, Taiwan
- Advanced Plant and Food Crop Biotechnology Center, National Chung Hsing University, Taichung 402202, Taiwan
- Innovation and Development Center of Sustainable Agriculture, National Chung Hsing University, Taichung 402202, Taiwan
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Yoon S, Heo H, Han H, Song DU, Bakken LR, Frostegård Å, Yoon S. Suggested role of NosZ in preventing N 2O inhibition of dissimilatory nitrite reduction to ammonium. mBio 2023; 14:e0154023. [PMID: 37737639 PMCID: PMC10653820 DOI: 10.1128/mbio.01540-23] [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: 06/23/2023] [Accepted: 07/31/2023] [Indexed: 09/23/2023] Open
Abstract
IMPORTANCE Dissimilatory nitrate/nitrite reduction to ammonium (DNRA) is a microbial energy-conserving process that reduces NO3 - and/or NO2 - to NH4 +. Interestingly, DNRA-catalyzing microorganisms possessing nrfA genes are occasionally found harboring nosZ genes encoding nitrous oxide reductases, i.e., the only group of enzymes capable of removing the potent greenhouse gas N2O. Here, through a series of physiological experiments examining DNRA metabolism in one of such microorganisms, Bacillus sp. DNRA2, we have discovered that N2O may delay the transition to DNRA upon an oxic-to-anoxic transition, unless timely removed by the nitrous oxide reductases. These observations suggest a novel explanation as to why some nrfA-possessing microorganisms have retained nosZ genes: to remove N2O that may otherwise interfere with the transition from O2 respiration to DNRA.
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Affiliation(s)
- Sojung Yoon
- Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, South Korea
| | - Hokwan Heo
- Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, South Korea
| | - Heejoo Han
- Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, South Korea
| | - Dong-Uk Song
- Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, South Korea
| | - Lars R. Bakken
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway
| | - Åsa Frostegård
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway
| | - Sukhwan Yoon
- Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, South Korea
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Patwardhan S, Phan J, Smedile F, Vetriani C. The Genome of Varunaivibrio sulfuroxidans Strain TC8 T, a Metabolically Versatile Alphaproteobacterium from the Tor Caldara Gas Vents in the Tyrrhenian Sea. Microorganisms 2023; 11:1366. [PMID: 37374867 DOI: 10.3390/microorganisms11061366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 05/02/2023] [Accepted: 05/15/2023] [Indexed: 06/29/2023] Open
Abstract
Varunaivibrio sulfuroxidans type strain TC8T is a mesophilic, facultatively anaerobic, facultatively chemolithoautotrophic alphaproteobacterium isolated from a sulfidic shallow-water marine gas vent located at Tor Caldara, Tyrrhenian Sea, Italy. V. sulfuroxidans belongs to the family Thalassospiraceae within the Alphaproteobacteria, with Magnetovibrio blakemorei as its closest relative. The genome of V. sulfuroxidans encodes the genes involved in sulfur, thiosulfate and sulfide oxidation, as well as nitrate and oxygen respiration. The genome encodes the genes involved in carbon fixation via the Calvin-Benson-Bassham cycle, in addition to genes involved in glycolysis and the TCA cycle, indicating a mixotrophic lifestyle. Genes involved in the detoxification of mercury and arsenate are also present. The genome also encodes a complete flagellar complex, one intact prophage and one CRISPR, as well as a putative DNA uptake mechanism mediated by the type IVc (aka Tad pilus) secretion system. Overall, the genome of Varunaivibrio sulfuroxidans highlights the organism's metabolic versatility, a characteristic that makes this strain well-adapted to the dynamic environmental conditions of sulfidic gas vents.
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Affiliation(s)
- Sushmita Patwardhan
- Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ 08901, USA
| | - Jonathan Phan
- Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, NJ 08901, USA
| | - Francesco Smedile
- Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ 08901, USA
| | - Costantino Vetriani
- Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ 08901, USA
- Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, NJ 08901, USA
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7
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Keuschnig C, Vogel TM, Barbaro E, Spolaor A, Koziol K, Björkman MP, Zdanowicz C, Gallet JC, Luks B, Layton R, Larose C. Selection processes of Arctic seasonal glacier snowpack bacterial communities. MICROBIOME 2023; 11:35. [PMID: 36864462 PMCID: PMC9979512 DOI: 10.1186/s40168-023-01473-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Accepted: 01/24/2023] [Indexed: 06/18/2023]
Abstract
BACKGROUND Arctic snowpack microbial communities are continually subject to dynamic chemical and microbial input from the atmosphere. As such, the factors that contribute to structuring their microbial communities are complex and have yet to be completely resolved. These snowpack communities can be used to evaluate whether they fit niche-based or neutral assembly theories. METHODS We sampled snow from 22 glacier sites on 7 glaciers across Svalbard in April during the maximum snow accumulation period and prior to the melt period to evaluate the factors that drive snowpack metataxonomy. These snowpacks were seasonal, accumulating in early winter on bare ice and firn and completely melting out in autumn. Using a Bayesian fitting strategy to evaluate Hubbell's Unified Neutral Theory of Biodiversity at multiple sites, we tested for neutrality and defined immigration rates at different taxonomic levels. Bacterial abundance and diversity were measured and the amount of potential ice-nucleating bacteria was calculated. The chemical composition (anions, cations, organic acids) and particulate impurity load (elemental and organic carbon) of the winter and spring snowpack were also characterized. We used these data in addition to geographical information to assess possible niche-based effects on snow microbial communities using multivariate and variable partitioning analysis. RESULTS While certain taxonomic signals were found to fit the neutral assembly model, clear evidence of niche-based selection was observed at most sites. Inorganic chemistry was not linked directly to diversity, but helped to identify predominant colonization sources and predict microbial abundance, which was tightly linked to sea spray. Organic acids were the most significant predictors of microbial diversity. At low organic acid concentrations, the snow microbial structure represented the seeding community closely, and evolved away from it at higher organic acid concentrations, with concomitant increases in bacterial numbers. CONCLUSIONS These results indicate that environmental selection plays a significant role in structuring snow microbial communities and that future studies should focus on activity and growth. Video Abstract.
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Affiliation(s)
- Christoph Keuschnig
- Formerly at Univ Lyon, CNRS, INSA Lyon, Université Claude Bernard Lyon 1, Ecole Centrale de Lyon, Ampère, UMR5005, 69134, Ecully Cedex, France
- Currently at Interface Geochemistry, German Research Center for Geosciences, GFZ, Potsdam, Germany
| | - Timothy M Vogel
- Univ Lyon, CNRS, INSA Lyon, Université Claude Bernard Lyon 1, Ecole Centrale de Lyon, Ampère, UMR5005, 69134, Ecully Cedex, France
| | - Elena Barbaro
- Institute of Polar Sciences, ISP-CNR, Via Torino 155, 30170, Venice Mestre, Italy
- Department of Environmental Sciences, Informatics and Statistics, Ca' Foscari University of Venice, Via Torino 155, 30172, Venice, Italy
| | - Andrea Spolaor
- Institute of Polar Sciences, ISP-CNR, Via Torino 155, 30170, Venice Mestre, Italy
- Department of Environmental Sciences, Informatics and Statistics, Ca' Foscari University of Venice, Via Torino 155, 30172, Venice, Italy
| | - Krystyna Koziol
- Department of Environmental Change and Geochemistry, Faculty of Geographical Sciences, the Kazimierz Wielki University in Bydgoszcz, Bydgoszcz, Poland
| | - Mats P Björkman
- Department of Earth Sciences, University of Gothenburg, Box 460, SE-40530, Gothenburg, Sweden
| | - Christian Zdanowicz
- Department of Earth Sciences, Uppsala University, Villavägen 16, SE-75236, Uppsala, Sweden
| | | | - Bartłomiej Luks
- Institute of Geophysics, Polish Academy of Sciences, Księcia Janusza 64, 01-452, Warsaw, Poland
| | - Rose Layton
- Formerly at Univ Lyon, CNRS, INSA Lyon, Université Claude Bernard Lyon 1, Ecole Centrale de Lyon, Ampère, UMR5005, 69134, Ecully Cedex, France
| | - Catherine Larose
- Univ Lyon, CNRS, INSA Lyon, Université Claude Bernard Lyon 1, Ecole Centrale de Lyon, Ampère, UMR5005, 69134, Ecully Cedex, France.
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Insight into the Cold Adaptation Mechanism of an Aerobic Denitrifying Bacterium: Bacillus simplex H-b. Appl Environ Microbiol 2023; 89:e0192822. [PMID: 36656033 PMCID: PMC9972999 DOI: 10.1128/aem.01928-22] [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: 01/20/2023] Open
Abstract
Psychrophilic bacteria with aerobic denitrification ability have promising potential for application in nitrogen-contaminated wastewater treatment, especially under cold conditions. A better understanding of the cold adaptation mechanism during aerobic denitrification would be beneficial for the practical application of this type of functional bacterium. In this study, Bacillus simplex H-b with good denitrification performance at 5°C was used to investigate the corresponding cold tolerance mechanism. Transcriptomics and nitrogen removal characterization experiments were conducted at different temperatures (5°C, 20°C, and 30°C). At low temperatures, more nitrogen was utilized for assimilation, accompanied by the accumulation of ATP and extracellular polymeric substances (EPS), rather than transforming inorganic nitrogen in the dissimilation pathway. In addition, the proportion of unsaturated fatty acids was higher in strains cultured at low temperatures. At the molecular level, the adjustment of membrane transport, synthesis of cofactors and vitamins, and transcriptional regulators might contribute to the survival of the strain under cold conditions. Moreover, nucleotide precursor synthesis, translation, and oxidative and temperature stress response mechanisms also enhanced the resistance of strain H-b to low temperatures. The results suggest that combining multiple regulatory mechanisms and synergistic adaptation to cold stress enabled the growth and relatively high nitrogen removal rate (27.22%) of strain H-b at 5°C. By clarifying the mechanism of regulation and cold resistance of strain H-b, a theoretical foundation for enhancing the application potential of this functional bacterium for nitrogen-contaminated wastewater treatment was provided. IMPORTANCE The newly isolated aerobic denitrifying bacterium Bacillus simplex H-b removed various forms of inorganic nitrogen (nitrate, nitrite, and ammonium) from wastewater, even when the temperature was as low as 5°C. Although this environmentally functional bacterium has been suggested as a promising candidate for nitrogen-contaminated water treatment at low temperatures, understanding its cold adaptation mechanism during aerobic denitrification is limited. In this study, the cold tolerance mechanism of this strain was comprehensively explained. Furthermore, a theoretical basis for the practical application of this type of functional bacterium for nitrogen removal in cold regions is provided. The study expands our understanding of the survival strategy of psychrophilic bacteria and hence supports their further utilization in wastewater treatment applications.
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Liu X, Wang H, Wang W, Cheng X, Wang Y, Li Q, Li L, Ma L, Lu X, Tuovinen OH. Nitrate determines the bacterial habitat specialization and impacts microbial functions in a subsurface karst cave. Front Microbiol 2023; 14:1115449. [PMID: 36846803 PMCID: PMC9947541 DOI: 10.3389/fmicb.2023.1115449] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2022] [Accepted: 01/19/2023] [Indexed: 02/11/2023] Open
Abstract
Karst caves are usually considered as natural laboratories to study pristine microbiomes in subsurface biosphere. However, effects of the increasingly detected nitrate in underground karst ecosystem due to the acid rain impact on microbiota and their functions in subsurface karst caves have remained largely unknown. In this study, samples of weathered rocks and sediments were collected from the Chang Cave, Hubei province and subjected to high-throughput sequencing of 16S rRNA genes. The results showed that nitrate significantly impacted bacterial compositions, interactions, and functions in different habitats. Bacterial communities clustered according to their habitats with distinguished indicator groups identified for each individual habitat. Nitrate shaped the overall bacterial communities across two habitats with a contribution of 27.2%, whereas the pH and TOC, respectively, structured bacterial communities in weathered rocks and sediments. Alpha and beta diversities of bacterial communities increased with nitrate concentration in both habitats, with nitrate directly affecting alpha diversity in sediments, but indirectly on weathered rocks by lowering pH. Nitrate impacted more on bacterial communities in weathered rocks at the genus level than in sediments because more genera significantly correlated with nitrate concentration in weathered rocks. Diverse keystone taxa involved in nitrogen cycling were identified in the co-occurrence networks such as nitrate reducers, ammonium-oxidizers, and N2-fixers. Tax4Fun2 analysis further confirmed the dominance of genes involved in nitrogen cycling. Genes of methane metabolism and carbon fixation were also dominant. The dominance of dissimilatory and assimilatory nitrate reduction in nitrogen cycling substantiated nitrate impact on bacterial functions. Our results for the first time revealed the impact of nitrate on subsurface karst ecosystem in terms of bacterial compositions, interactions, and functions, providing an important reference for further deciphering the disturbance of human activities on the subsurface biosphere.
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Affiliation(s)
- Xiaoyan Liu
- State Key Laboratory of Geobiology and Environmental Geology, China University of Geosciences, Wuhan, China
- School of Environmental Studies, China University of Geosciences, Wuhan, China
| | - Hongmei Wang
- State Key Laboratory of Geobiology and Environmental Geology, China University of Geosciences, Wuhan, China
- School of Environmental Studies, China University of Geosciences, Wuhan, China
| | - Weiqi Wang
- State Key Laboratory of Geobiology and Environmental Geology, China University of Geosciences, Wuhan, China
- School of Environmental Studies, China University of Geosciences, Wuhan, China
| | - Xiaoyu Cheng
- State Key Laboratory of Geobiology and Environmental Geology, China University of Geosciences, Wuhan, China
- School of Environmental Studies, China University of Geosciences, Wuhan, China
| | - Yiheng Wang
- State Key Laboratory of Geobiology and Environmental Geology, China University of Geosciences, Wuhan, China
| | - Qing Li
- State Key Laboratory of Geobiology and Environmental Geology, China University of Geosciences, Wuhan, China
| | - Lu Li
- State Key Laboratory of Geobiology and Environmental Geology, China University of Geosciences, Wuhan, China
| | - Liyuan Ma
- School of Environmental Studies, China University of Geosciences, Wuhan, China
| | - Xiaolu Lu
- School of Environmental Studies, China University of Geosciences, Wuhan, China
| | - Olli H. Tuovinen
- Department of Microbiology, Ohio State University, Columbus, OH, United States
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Yin S, Zhang W, Tong T, Yu C, Chang X, Chen K, Xing Y, Yang Y. Feedstock-dependent abundance of functional genes related to nitrogen transformation controlled nitrogen loss in composting. BIORESOURCE TECHNOLOGY 2022; 361:127678. [PMID: 35872270 DOI: 10.1016/j.biortech.2022.127678] [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: 06/18/2022] [Revised: 07/18/2022] [Accepted: 07/19/2022] [Indexed: 06/15/2023]
Abstract
The objective of this work was to explore how selection of feedstock affects nitrogen cycle genes during composting, which eventually determines the nitrogen loss. Four composting mixes (CM: chicken manure; SM: sheep manure; MM1/3: mixed manure with CM: SM = 1:3 w/w, MM3/1: CM: SM = 3:1 w/w) were investigated. Results showed that adding 25 % and 75 % SM to CM reduced 26.5 % and 57.9 % nitrogen loss, respectively. CM contained more ammonification genes and nrfA gene, while SM had more denitrification genes. Nitrogen fixation genes in CM were slightly higher than that in SM at the initial stage, but they sharply dropped off as the composting entered the high temperature stage. MM1/3 showed significantly reduced ammonification genes than CM, and increased nitrogen fixation and NH4+ assimilation genes. Therefore, adding SM to CM could change the abundance of genes and enzymes related to nitrogen cycle to reduce nitrogen loss.
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Affiliation(s)
- Siqian Yin
- College of Resources and Environmental Sciences, Gansu Agricultural University, Lanzhou 730070, PR China
| | - Wenming Zhang
- College of Resources and Environmental Sciences, Gansu Agricultural University, Lanzhou 730070, PR China.
| | - Tianjian Tong
- Department of Agriculture and Biosystem Engineering, Iowa State University, Ames 50010, USA
| | - Chenxu Yu
- Department of Agriculture and Biosystem Engineering, Iowa State University, Ames 50010, USA
| | - Xinyi Chang
- College of Resources and Environmental Sciences, Gansu Agricultural University, Lanzhou 730070, PR China
| | - Kaishan Chen
- College of Resources and Environmental Sciences, Gansu Agricultural University, Lanzhou 730070, PR China
| | - Yanhong Xing
- College of Resources and Environmental Sciences, Gansu Agricultural University, Lanzhou 730070, PR China
| | - Yingxiang Yang
- College of Resources and Environmental Sciences, Gansu Agricultural University, Lanzhou 730070, PR China
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11
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Pessi IS, Viitamäki S, Virkkala AM, Eronen-Rasimus E, Delmont TO, Marushchak ME, Luoto M, Hultman J. In-depth characterization of denitrifier communities across different soil ecosystems in the tundra. ENVIRONMENTAL MICROBIOME 2022; 17:30. [PMID: 35690846 PMCID: PMC9188126 DOI: 10.1186/s40793-022-00424-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 06/03/2022] [Indexed: 06/15/2023]
Abstract
BACKGROUND In contrast to earlier assumptions, there is now mounting evidence for the role of tundra soils as important sources of the greenhouse gas nitrous oxide (N2O). However, the microorganisms involved in the cycling of N2O in this system remain largely uncharacterized. Since tundra soils are variable sources and sinks of N2O, we aimed at investigating differences in community structure across different soil ecosystems in the tundra. RESULTS We analysed 1.4 Tb of metagenomic data from soils in northern Finland covering a range of ecosystems from dry upland soils to water-logged fens and obtained 796 manually binned and curated metagenome-assembled genomes (MAGs). We then searched for MAGs harbouring genes involved in denitrification, an important process driving N2O emissions. Communities of potential denitrifiers were dominated by microorganisms with truncated denitrification pathways (i.e., lacking one or more denitrification genes) and differed across soil ecosystems. Upland soils showed a strong N2O sink potential and were dominated by members of the Alphaproteobacteria such as Bradyrhizobium and Reyranella. Fens, which had in general net-zero N2O fluxes, had a high abundance of poorly characterized taxa affiliated with the Chloroflexota lineage Ellin6529 and the Acidobacteriota subdivision Gp23. CONCLUSIONS By coupling an in-depth characterization of microbial communities with in situ measurements of N2O fluxes, our results suggest that the observed spatial patterns of N2O fluxes in the tundra are related to differences in the composition of denitrifier communities.
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Affiliation(s)
- Igor S. Pessi
- Department of Microbiology, University of Helsinki, Viikinkaari 9, 00014 Helsinki, Finland
- Helsinki Institute of Sustainability Science (HELSUS), Yliopistonkatu 3, 00014 Helsinki, Finland
| | - Sirja Viitamäki
- Department of Microbiology, University of Helsinki, Viikinkaari 9, 00014 Helsinki, Finland
| | - Anna-Maria Virkkala
- Woodwell Climate Research Center, 149 Woods Hole Road, Falmouth, MA 02540-1644 USA
- Department of Geosciences and Geography, University of Helsinki, Gustaf Hällströmin katu 2, 00014 Helsinki, Finland
| | - Eeva Eronen-Rasimus
- Department of Microbiology, University of Helsinki, Viikinkaari 9, 00014 Helsinki, Finland
- Marine Research Centre, Finnish Environment Institute (SYKE), Agnes Sjöbergin katu 2, 00790 Helsinki, Finland
| | - Tom O. Delmont
- Génomique Métabolique, Genoscope, Institut François-Jacob, CEA, CNRS, Université d’Evry, Université Paris-Saclay, 91057 Evry, France
| | - Maija E. Marushchak
- Department of Biological and Environmental Science, University of Jyväskylä, 40014 Jyväskylä, Finland
- Department of Environmental and Biological Sciences, University of Eastern Finland, 70211 Kuopio, Finland
| | - Miska Luoto
- Department of Geosciences and Geography, University of Helsinki, Gustaf Hällströmin katu 2, 00014 Helsinki, Finland
| | - Jenni Hultman
- Department of Microbiology, University of Helsinki, Viikinkaari 9, 00014 Helsinki, Finland
- Helsinki Institute of Sustainability Science (HELSUS), Yliopistonkatu 3, 00014 Helsinki, Finland
- Natural Resources Institute Finland (LUKE), Latokartanonkaari 9, 00790 Helsinki, Finland
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12
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Shu H, Sun H, Huang W, Zhao Y, Ma Y, Chen W, Sun Y, Chen X, Zhong P, Yang H, Wu X, Huang M, Liao S. Nitrogen removal characteristics and potential application of the heterotrophic nitrifying-aerobic denitrifying bacteria Pseudomonas mendocina S16 and Enterobacter cloacae DS'5 isolated from aquaculture wastewater ponds. BIORESOURCE TECHNOLOGY 2022; 345:126541. [PMID: 34910970 DOI: 10.1016/j.biortech.2021.126541] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 12/05/2021] [Accepted: 12/06/2021] [Indexed: 06/14/2023]
Abstract
Two biosafety strains, identified as Pseudomonas mendocina S16 and Enterobacter cloacae DS'5, were isolated from freshwater aquaculture ponds and showed significant heterotrophic nitrification-aerobic denitrification abilities. Within 48 h, the inorganic nitrogen removal efficiencies in the two strains were 66.59 %-97.97 % (S16) and 72.27 %-96.44 % (DS'5). The optimal conditions for organic nitrogen removal of the two strains were temperature 20-35 °C and carbon/nitrogen (C/N) ratio 10-20 while using sodium citrate as the carbon source. Sequence amplification demonstrated the presence of the denitrification genes in both the two strains, and quantitative real-time PCR results showed that the coupled expression of nap + nar would improve the nitrate removal rate in S16. The nitrogen removal efficiencies of the two strains in immobilization culture systems were 79.80 %-98.58 % (S16) and 60.80 %-98.40 % (DS'5). This study indicated the great potential application of the two strains in aquaculture tail water treatment.
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Affiliation(s)
- Hu Shu
- Aquatic Research Center, Key Laboratory of Animal Nutrition and Feed Science in South China of Ministry of Agriculture and Rural Affairs, Guangdong Key Laboratory of Animal Breeding and Nutrition, Institute of Animal Science, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China; School of Life Science/School of Environmental Science and Engineering, Guangzhou University, Guangzhou 510006, China
| | - Huiming Sun
- Aquatic Research Center, Key Laboratory of Animal Nutrition and Feed Science in South China of Ministry of Agriculture and Rural Affairs, Guangdong Key Laboratory of Animal Breeding and Nutrition, Institute of Animal Science, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China; School of Life Science/School of Environmental Science and Engineering, Guangzhou University, Guangzhou 510006, China
| | - Wen Huang
- Aquatic Research Center, Key Laboratory of Animal Nutrition and Feed Science in South China of Ministry of Agriculture and Rural Affairs, Guangdong Key Laboratory of Animal Breeding and Nutrition, Institute of Animal Science, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China; School of Life Science/School of Environmental Science and Engineering, Guangzhou University, Guangzhou 510006, China; College of Marine Sciences, South China Agricultural University, Guangzhou 510642, China.
| | - Yang Zhao
- Aquatic Research Center, Key Laboratory of Animal Nutrition and Feed Science in South China of Ministry of Agriculture and Rural Affairs, Guangdong Key Laboratory of Animal Breeding and Nutrition, Institute of Animal Science, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China; School of Life Science/School of Environmental Science and Engineering, Guangzhou University, Guangzhou 510006, China
| | - Yonghao Ma
- Aquatic Research Center, Key Laboratory of Animal Nutrition and Feed Science in South China of Ministry of Agriculture and Rural Affairs, Guangdong Key Laboratory of Animal Breeding and Nutrition, Institute of Animal Science, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China; School of Life Science/School of Environmental Science and Engineering, Guangzhou University, Guangzhou 510006, China
| | - Wei Chen
- Aquatic Research Center, Key Laboratory of Animal Nutrition and Feed Science in South China of Ministry of Agriculture and Rural Affairs, Guangdong Key Laboratory of Animal Breeding and Nutrition, Institute of Animal Science, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China; School of Life Science/School of Environmental Science and Engineering, Guangzhou University, Guangzhou 510006, China
| | - Yuping Sun
- Aquatic Research Center, Key Laboratory of Animal Nutrition and Feed Science in South China of Ministry of Agriculture and Rural Affairs, Guangdong Key Laboratory of Animal Breeding and Nutrition, Institute of Animal Science, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China
| | - Xiaoying Chen
- Aquatic Research Center, Key Laboratory of Animal Nutrition and Feed Science in South China of Ministry of Agriculture and Rural Affairs, Guangdong Key Laboratory of Animal Breeding and Nutrition, Institute of Animal Science, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China
| | - Ping Zhong
- Aquatic Research Center, Key Laboratory of Animal Nutrition and Feed Science in South China of Ministry of Agriculture and Rural Affairs, Guangdong Key Laboratory of Animal Breeding and Nutrition, Institute of Animal Science, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China
| | - Huirong Yang
- College of Marine Sciences, South China Agricultural University, Guangzhou 510642, China
| | - Xiaopeng Wu
- Aquatic Research Center, Key Laboratory of Animal Nutrition and Feed Science in South China of Ministry of Agriculture and Rural Affairs, Guangdong Key Laboratory of Animal Breeding and Nutrition, Institute of Animal Science, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China
| | - Minwei Huang
- Aquatic Research Center, Key Laboratory of Animal Nutrition and Feed Science in South China of Ministry of Agriculture and Rural Affairs, Guangdong Key Laboratory of Animal Breeding and Nutrition, Institute of Animal Science, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China
| | - Sentai Liao
- Aquatic Research Center, Key Laboratory of Animal Nutrition and Feed Science in South China of Ministry of Agriculture and Rural Affairs, Guangdong Key Laboratory of Animal Breeding and Nutrition, Institute of Animal Science, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China
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13
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Lehnert N, Kim E, Dong HT, Harland JB, Hunt AP, Manickas EC, Oakley KM, Pham J, Reed GC, Alfaro VS. The Biologically Relevant Coordination Chemistry of Iron and Nitric Oxide: Electronic Structure and Reactivity. Chem Rev 2021; 121:14682-14905. [PMID: 34902255 DOI: 10.1021/acs.chemrev.1c00253] [Citation(s) in RCA: 101] [Impact Index Per Article: 33.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Nitric oxide (NO) is an important signaling molecule that is involved in a wide range of physiological and pathological events in biology. Metal coordination chemistry, especially with iron, is at the heart of many biological transformations involving NO. A series of heme proteins, nitric oxide synthases (NOS), soluble guanylate cyclase (sGC), and nitrophorins, are responsible for the biosynthesis, sensing, and transport of NO. Alternatively, NO can be generated from nitrite by heme- and copper-containing nitrite reductases (NIRs). The NO-bearing small molecules such as nitrosothiols and dinitrosyl iron complexes (DNICs) can serve as an alternative vehicle for NO storage and transport. Once NO is formed, the rich reaction chemistry of NO leads to a wide variety of biological activities including reduction of NO by heme or non-heme iron-containing NO reductases and protein post-translational modifications by DNICs. Much of our understanding of the reactivity of metal sites in biology with NO and the mechanisms of these transformations has come from the elucidation of the geometric and electronic structures and chemical reactivity of synthetic model systems, in synergy with biochemical and biophysical studies on the relevant proteins themselves. This review focuses on recent advancements from studies on proteins and model complexes that not only have improved our understanding of the biological roles of NO but also have provided foundations for biomedical research and for bio-inspired catalyst design in energy science.
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Affiliation(s)
- Nicolai Lehnert
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Eunsuk Kim
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Hai T Dong
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Jill B Harland
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Andrew P Hunt
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Elizabeth C Manickas
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Kady M Oakley
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - John Pham
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Garrett C Reed
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Victor Sosa Alfaro
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
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14
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Shan J, Sanford RA, Chee-Sanford J, Ooi SK, Löffler FE, Konstantinidis KT, Yang WH. Beyond denitrification: The role of microbial diversity in controlling nitrous oxide reduction and soil nitrous oxide emissions. GLOBAL CHANGE BIOLOGY 2021; 27:2669-2683. [PMID: 33547715 DOI: 10.1111/gcb.15545] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 01/11/2021] [Indexed: 05/02/2023]
Abstract
Many biotic and abiotic processes contribute to nitrous oxide (N2 O) production in the biosphere, but N2 O consumption in the environment has heretofore been attributed primarily to canonical denitrifying microorganisms. The nosZ genes encoding the N2 O reductase enzyme, NosZ, responsible for N2 O reduction to dinitrogen are now known to include two distinct groups: the well-studied Clade I which denitrifiers typically possess, and the novel Clade II possessed by diverse groups of microorganisms, most of which are non-denitrifiers. Clade II N2 O reducers could play an important, previously unrecognized role in controlling N2 O emissions for several reasons, including: (1) the consumption of N2 O produced by processes other than denitrification, (2) hypothesized non-respiratory functions of NosZ as an electron sink or for N2 O detoxification, (3) possible differing enzyme kinetics of Clade II NosZ compared to Clade I NosZ, and (4) greater nosZ gene abundance for Clade II compared to Clade I in soils of many ecosystems. Despite the potential ecological significance of Clade II NosZ, a census of 800 peer-reviewed original research articles discussing nosZ and published from 2013 to 2019 showed that the percentage of articles evaluating or mentioning Clade II nosZ increased from 5% in 2013 to only 22% in 2019. The census revealed that the slowly spreading awareness of Clade II nosZ may result in part from disciplinary silos, with the percentage of nosZ articles mentioning Clade II nosZ ranging from 0% in Agriculture and Agronomy journals to 32% in Multidisciplinary Sciences journals. In addition, inconsistent nomenclature for Clade I nosZ and Clade II nosZ, with 17 different terminologies used in the literature, may have created confusion about the two distinct groups of N2 O reducers. We provide recommendations to accelerate advances in understanding the role of the diversity of N2 O reducers in regulating soil N2 O emissions.
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Affiliation(s)
- Jun Shan
- State Key Laboratory of Soil and Sustainable Agriculture, Changshu National Agro-Ecosystem Observation and Research Station, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China
| | - Robert A Sanford
- Department of Geology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Joanne Chee-Sanford
- Global Change and Photosynthesis Research Unit, United States Department of Agriculture - Agricultural Research Station,, Urbana, IL, USA
| | - Sean K Ooi
- Program in Ecology, Evolution, and Conservation Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Frank E Löffler
- Center for Environmental Biotechnology, Department of Microbiology, Department of Civil and Environmental Engineering, Department of Biosystems Engineering and Soil Science, University of Tennessee, Knoxville, TN, USA
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Konstantinos T Konstantinidis
- School of Civil and Environmental Engineering and School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA
| | - Wendy H Yang
- Departments of Plant Biology and Geology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
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15
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Asamoto CK, Rempfert KR, Luu VH, Younkin AD, Kopf SH. Enzyme-Specific Coupling of Oxygen and Nitrogen Isotope Fractionation of the Nap and Nar Nitrate Reductases. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:5537-5546. [PMID: 33687201 DOI: 10.1021/acs.est.0c07816] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Dissimilatory nitrate reduction (DNR) to nitrite is the first step in denitrification, the main process through which bioavailable nitrogen is removed from ecosystems. DNR is catalyzed by both cytosolic (Nar) and periplasmic (Nap) nitrate reductases and fractionates the stable isotopes of nitrogen (14N, 15N) and oxygen (16O, 18O), which is reflected in residual environmental nitrate pools. Data on the relationship between the pattern in oxygen vs nitrogen isotope fractionation (18ε/15ε) suggests that systematic differences exist between marine and terrestrial ecosystems that are not fully understood. We examined the 18ε/15ε of nitrate-reducing microorganisms that encode Nar, Nap, or both enzymes, as well as gene deletion mutants of Nar and Nap to test the hypothesis that enzymatic differences alone could explain the environmental observations. We find that the distribution of 18ε/15ε fractionation ratios of all examined nitrate reductases forms two distinct peaks centered around an 18ε/15ε proportionality of 0.55 (Nap) and 0.91 (Nar), with the notable exception of the Bacillus Nar reductases, which cluster isotopically with the Nap reductases. Our findings may explain differences in 18ε/15ε fractionation between marine and terrestrial systems and challenge current knowledge about Nar 18ε/15ε signatures.
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Affiliation(s)
- Ciara K Asamoto
- Department of Geological Sciences, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Kaitlin R Rempfert
- Department of Geological Sciences, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Victoria H Luu
- Department of Geosciences, Princeton University, Princeton, New Jersey 08544, United States
| | - Adam D Younkin
- Department of Geological Sciences, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Sebastian H Kopf
- Department of Geological Sciences, University of Colorado Boulder, Boulder, Colorado 80309, United States
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16
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Insight into the denitrification mechanism of Bacillus subtilis JD-014 and its application potential in bioremediation of nitrogen wastewater. Process Biochem 2021. [DOI: 10.1016/j.procbio.2021.02.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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17
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Li XM, Ding LJ, Zhu D, Zhu YG. Long-Term Fertilization Shapes the Putative Electrotrophic Microbial Community in Paddy Soils Revealed by Microbial Electrosynthesis Systems. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:3430-3441. [PMID: 33600162 DOI: 10.1021/acs.est.0c08022] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Electrotrophs play an important role in biogeochemical cycles, but the effects of long-term fertilization on electrotrophic communities in paddy soils remain unclear. Here, we explored the responses of electrotrophic communities in paddy soil-based microcosms to different long-term fertilization practices using microbial electrosynthesis systems (MESs), high-throughput quantitative PCR, and 16s rRNA gene-based Illumina sequencing techniques. Compared to the case in the unfertilized soil (CK), applications of only manure (M); only chemical nitrogen, phosphorous, and potassium fertilizers (NPK); and M plus NPK (MNPK) clearly changed the electrotrophic bacterial community structure. The Streptomyces genus of the Actinobacteria phylum was the dominant electrotroph in the CK, M, and MNPK soils. The latter two soils also favored Truepera of Deinococcus-Thermus or Arenimonas and Thioalkalispira of Proteobacteria. Furthermore, Pseudomonas of Proteobacteria and Bacillus of Firmicutes were major electrotrophs in the NPK soil. These electrotrophs consumed biocathodic currents coupled with nitrate reduction and recovered 18-38% of electrons via dissimilatory nitrate reduction to ammonium (DNRA). The increased abundances of the nrfA gene for DNRA induced by electrical potential further supported that the electrotrophs enhanced DNRA for all soils. These expand our knowledge about the diversity of electrotrophs and their roles in N cycle in paddy soils and highlight the importance of fertilization in shaping electrotrophic communities.
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Affiliation(s)
- Xiao-Min Li
- State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Shuangqing Road, No. 18, Haidian District, Beijing 100085, China
- Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Jimei Road, No. 1799, Jimei District, Xiamen 361021, China
- Zhejiang Key Laboratory of Urban Environmental Processes and Pollution Control, Ningbo Urban Environment Observation and Research Station, Chinese Academy of Sciences, Zhongke Road 88, Beilun District, Ningbo 315830, China
- University of Chinese Academy of Sciences, Yuquan Road, No. 19A, Shijingshan District, Beijing 100049, China
| | - Long-Jun Ding
- State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Shuangqing Road, No. 18, Haidian District, Beijing 100085, China
| | - Dong Zhu
- State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Shuangqing Road, No. 18, Haidian District, Beijing 100085, China
| | - Yong-Guan Zhu
- State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Shuangqing Road, No. 18, Haidian District, Beijing 100085, China
- Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Jimei Road, No. 1799, Jimei District, Xiamen 361021, China
- University of Chinese Academy of Sciences, Yuquan Road, No. 19A, Shijingshan District, Beijing 100049, China
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18
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Schwendner P, Jobson ME, Schuerger AC. Addition of anaerobic electron acceptors to solid media did not enhance growth of 125 spacecraft bacteria under simulated low-pressure Martian conditions. Sci Rep 2020; 10:18290. [PMID: 33106561 PMCID: PMC7588431 DOI: 10.1038/s41598-020-75222-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 10/06/2020] [Indexed: 11/25/2022] Open
Abstract
To protect Mars from microbial contamination, research on growth of microorganisms found in spacecraft assembly clean rooms under simulated Martian conditions is required. This study investigated the effects of low atmospheric pressure on the growth of chemoorganotrophic spacecraft bacteria and whether the addition of Mars relevant anaerobic electron acceptors might enhance growth. The 125 bacteria screened here were recovered from actual Mars spacecraft. Growth at 7 hPa, 0 °C, and a CO2-enriched anoxic atmosphere (called low-PTA conditions) was tested on five TSA-based media supplemented with anaerobic electron acceptors. None of the 125 spacecraft bacteria showed active growth under the tested low-PTA conditions and amended media. In contrast, a decrease in viability was observed in most cases. Growth curves of two hypopiezotolerant strains, Serratia liquefaciens and Trichococcus pasteurii, were performed to quantify the effects of the added anaerobic electron acceptors. Slight variations in growth rates were determined for both bacteria. However, the final cell densities were similar for all media tested, indicating no general preference for any specific anaerobic electron acceptor. By demonstrating that a broad diversity of chemoorganotrophic and culturable spacecraft bacteria do not grow under the tested conditions, we conclude that there may be low risk of growth of chemoorganotrophic bacteria typically recovered from Mars spacecraft during planetary protection bioburden screenings.
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Affiliation(s)
- Petra Schwendner
- Space Life Sciences Lab, University of Florida, 505 Odyssey Way, Exploration Park, Merritt Island, FL, 32953, USA.
| | - Mary-Elizabeth Jobson
- Space Life Sciences Lab, University of Florida, 505 Odyssey Way, Exploration Park, Merritt Island, FL, 32953, USA
| | - Andrew C Schuerger
- Space Life Sciences Lab, University of Florida, 505 Odyssey Way, Exploration Park, Merritt Island, FL, 32953, USA
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19
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Involvement of NO 3 - in Ecophysiological Regulation of Dissimilatory Nitrate/Nitrite Reduction to Ammonium (DNRA) Is Implied by Physiological Characterization of Soil DNRA Bacteria Isolated via a Colorimetric Screening Method. Appl Environ Microbiol 2020; 86:AEM.01054-20. [PMID: 32631862 DOI: 10.1128/aem.01054-20] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 06/29/2020] [Indexed: 11/20/2022] Open
Abstract
Dissimilatory nitrate/nitrite reduction to ammonium (DNRA) has recently regained attention as a nitrogen retention pathway that may potentially be harnessed to alleviate nitrogen loss resulting from denitrification. Until recently, the ecophysiology of DNRA bacteria inhabiting agricultural soils has remained largely unexplored, due to the difficulty in targeted enrichment and isolation of DNRA microorganisms. In this study, >100 DNRA bacteria were isolated from NO3 --reducing anoxic enrichment cultures established with rice paddy soils using a newly developed colorimetric screening method. Six of these isolates, each assigned to a different genus, were characterized to improve the understanding of DNRA physiology. All the isolates carried nrfA and/or nirB, and the Bacillus sp. strain possessed a clade II nosZ gene conferring the capacity for N2O reduction. A common prominent physiological feature observed in the isolates was NO2 - accumulation before NH4 + production, which was further examined with Citrobacter sp. strain DNRA3 (possessing nrfA and nirB) and Enterobacter sp. strain DNRA5 (possessing only nirB). Both isolates showed inhibition of NO2 --to-NH4 + reduction at submillimolar NO3 - concentrations and downregulation of nrfA or nirB transcription when NO3 - was being reduced to NO2 - In batch and chemostat experiments, both isolates produced NH4 + from NO3 - reduction when incubated with excess organic electron donors, while incubation with excess NO3 - resulted in NO2 - buildup but no substantial NH4 + production, presumably due to inhibitory NO3 - concentrations. This previously overlooked link between NO3 - repression of NO2 --to-NH4 + reduction and the C-to-N ratio regulation of DNRA activity may be a key mechanism underpinning denitrification-versus-DNRA competition in soil.IMPORTANCE Dissimilatory nitrate/nitrite reduction to ammonium (DNRA) is an anaerobic microbial pathway that competes with denitrification for common substrates NO3 - and NO2 - Unlike denitrification, which leads to nitrogen loss and N2O emission, DNRA reduces NO3 - and NO2 - to NH4 +, a reactive nitrogen compound with a higher tendency to be retained in the soil matrix. Therefore, stimulation of DNRA has often been proposed as a strategy to improve fertilizer efficiency and reduce greenhouse gas emissions. Such attempts have been hampered by lack of insights into soil DNRA bacterial ecophysiology. Here, we have developed a new screening method for isolating DNRA-catalyzing organisms from agricultural soils without apparent DNRA activity. Physiological characteristics of six DNRA isolates were closely examined, disclosing a previously overlooked link between NO3 - repression of NO2 --to-NH4 + reduction and the C-to-N ratio regulation of DNRA activity, which may be a key to understanding why DNRA activity is rarely observed at substantial levels in nitrogen-rich agricultural soils.
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Ferousi C, Majer SH, DiMucci IM, Lancaster KM. Biological and Bioinspired Inorganic N-N Bond-Forming Reactions. Chem Rev 2020; 120:5252-5307. [PMID: 32108471 PMCID: PMC7339862 DOI: 10.1021/acs.chemrev.9b00629] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The metallobiochemistry underlying the formation of the inorganic N-N-bond-containing molecules nitrous oxide (N2O), dinitrogen (N2), and hydrazine (N2H4) is essential to the lifestyles of diverse organisms. Similar reactions hold promise as means to use N-based fuels as alternative carbon-free energy sources. This review discusses research efforts to understand the mechanisms underlying biological N-N bond formation in primary metabolism and how the associated reactions are tied to energy transduction and organismal survival. These efforts comprise studies of both natural and engineered metalloenzymes as well as synthetic model complexes.
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Affiliation(s)
- Christina Ferousi
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, United States
| | - Sean H Majer
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, United States
| | - Ida M DiMucci
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, United States
| | - Kyle M Lancaster
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, United States
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Vuono DC, Read RW, Hemp J, Sullivan BW, Arnone JA, Neveux I, Blank RR, Loney E, Miceli D, Winkler MKH, Chakraborty R, Stahl DA, Grzymski JJ. Resource Concentration Modulates the Fate of Dissimilated Nitrogen in a Dual-Pathway Actinobacterium. Front Microbiol 2019; 10:3. [PMID: 30723459 PMCID: PMC6349771 DOI: 10.3389/fmicb.2019.00003] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Accepted: 01/07/2019] [Indexed: 11/30/2022] Open
Abstract
Respiratory ammonification and denitrification are two evolutionarily unrelated dissimilatory nitrogen (N) processes central to the global N cycle, the activity of which is thought to be controlled by carbon (C) to nitrate (NO3 -) ratio. Here we find that Intrasporangium calvum C5, a novel dual-pathway denitrifier/respiratory ammonifier, disproportionately utilizes ammonification rather than denitrification when grown under low C concentrations, even at low C:NO3 - ratios. This finding is in conflict with the paradigm that high C:NO3 - ratios promote ammonification and low C:NO3 - ratios promote denitrification. We find that the protein atomic composition for denitrification modules (NirK) are significantly cost minimized for C and N compared to ammonification modules (NrfA), indicating that limitation for C and N is a major evolutionary selective pressure imprinted in the architecture of these proteins. The evolutionary precedent for these findings suggests ecological importance for microbial activity as evidenced by higher growth rates when I. calvum grows predominantly using its ammonification pathway and by assimilating its end-product (ammonium) for growth under ammonium-free conditions. Genomic analysis of I. calvum further reveals a versatile ecophysiology to cope with nutrient stress and redox conditions. Metabolite and transcriptional profiles during growth indicate that enzyme modules, NrfAH and NirK, are not constitutively expressed but rather induced by nitrite production via NarG. Mechanistically, our results suggest that pathway selection is driven by intracellular redox potential (redox poise), which may be lowered when resource concentrations are low, thereby decreasing catalytic activity of upstream electron transport steps (i.e., the bc1 complex) needed for denitrification enzymes. Our work advances our understanding of the biogeochemical flexibility of N-cycling organisms, pathway evolution, and ecological food-webs.
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Affiliation(s)
- David C. Vuono
- Division of Earth and Ecosystem Sciences, Desert Research Institute, Reno, NV, United States
- Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, United States
| | - Robert W. Read
- Division of Earth and Ecosystem Sciences, Desert Research Institute, Reno, NV, United States
| | - James Hemp
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, United States
| | - Benjamin W. Sullivan
- Department of Natural Resources and Environmental Science, University of Nevada, Reno, Reno, NV, United States
| | - John A. Arnone
- Division of Earth and Ecosystem Sciences, Desert Research Institute, Reno, NV, United States
| | - Iva Neveux
- Division of Earth and Ecosystem Sciences, Desert Research Institute, Reno, NV, United States
| | - Robert R. Blank
- Agricultural Research Service, United States Department of Agriculture, Reno, NV, United States
| | - Evan Loney
- Division of Earth and Ecosystem Sciences, Desert Research Institute, Reno, NV, United States
| | - David Miceli
- Division of Earth and Ecosystem Sciences, Desert Research Institute, Reno, NV, United States
| | - Mari-Karoliina H. Winkler
- Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, United States
| | - Romy Chakraborty
- Earth and Environmental Sciences Area, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
| | - David A. Stahl
- Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, United States
| | - Joseph J. Grzymski
- Division of Earth and Ecosystem Sciences, Desert Research Institute, Reno, NV, United States
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Cho TJ, Rhee MS. Underrecognized niche of spore-forming bacilli as a nitrite-producer isolated from the processing lines and end-products of powdered infant formula. Food Microbiol 2018; 80:50-61. [PMID: 30704596 DOI: 10.1016/j.fm.2018.12.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Revised: 11/20/2018] [Accepted: 12/21/2018] [Indexed: 01/14/2023]
Abstract
Although nitrite in powdered milk formula (PIF) is a recognized health risk for infants, the presence of nitrite in PIF has only been investigated as a chemical contaminant during the inspection of end-products. The risk posed by microbial sources of nitrite during the PIF manufacturing process has not been considered. This is the first study to report the taxonomy and physiological characteristics of nitrite-producing bacteria isolated from PIF processing environments. All isolates identified as nitrite-producers (133 out of 501 strains collected over four years) from work-in-process and end-products of PIF were spore-forming bacilli. Nitrite-producing metabolism under PIF processing conditions was found in not only thermophilic isolates (3 Bacillus, 60 Geobacillus from 63 strains; 100%) but also in mesophilic isolates (65 Bacillus, 1 Anoxybacillus from 70 strains; 65.7%). Geobacillus was the only highly heat-resistant sporeformer and vigorous nitrite-producer exhibiting dramatic increases in nitrite over short periods of incubation (a maximum value within 3 h). High conversions of nitrate to nitrite (up to 88.8%) was also observed, highlighting bacteria as a key source of nitrite in PIF processing lines. Further research into the diversity of metabolic activity observed in this study can facilitate specialized management of nitrite-producers in PIF processing lines.
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Affiliation(s)
- Tae Jin Cho
- Department of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul, 02841, South Korea
| | - Min Suk Rhee
- Department of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul, 02841, South Korea.
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Anderson CR, Peterson ME, Frampton RA, Bulman SR, Keenan S, Curtin D. Rapid increases in soil pH solubilise organic matter, dramatically increase denitrification potential and strongly stimulate microorganisms from the Firmicutes phylum. PeerJ 2018; 6:e6090. [PMID: 30581677 PMCID: PMC6295159 DOI: 10.7717/peerj.6090] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 11/08/2018] [Indexed: 01/13/2023] Open
Abstract
Rapid and transient changes in pH frequently occur in soil, impacting dissolved organic matter (DOM) and other chemical attributes such as redox and oxygen conditions. Although we have detailed knowledge on microbial adaptation to long-term pH changes, little is known about the response of soil microbial communities to rapid pH change, nor how excess DOM might affect key aspects of microbial N processing. We used potassium hydroxide (KOH) to induce a range of soil pH changes likely to be observed after livestock urine or urea fertilizer application to soil. We also focus on nitrate reductive processes by incubating microcosms under anaerobic conditions for up to 48 h. Soil pH was elevated from 4.7 to 6.7, 8.3 or 8.8, and up to 240-fold higher DOM was mobilized by KOH compared to the controls. This increased microbial metabolism but there was no correlation between DOM concentrations and CO2 respiration nor N-metabolism rates. Microbial communities became dominated by Firmicutes bacteria within 16 h, while few changes were observed in the fungal communities. Changes in N-biogeochemistry were rapid and denitrification enzyme activity (DEA) increased up to 25-fold with the highest rates occurring in microcosms at pH 8.3 that had been incubated for 24-hour prior to measuring DEA. Nitrous oxide reductase was inactive in the pH 4.7 controls but at pH 8.3 the reduction rates exceeded 3,000 ng N2-N g-1 h-1 in the presence of native DOM. Evidence for dissimilatory nitrate reduction to ammonium and/or organic matter mineralisation was observed with ammonium increasing to concentrations up to 10 times the original native soil concentrations while significant concentrations of nitrate were utilised. Pure isolates from the microcosms were dominated by Bacillus spp. and exhibited varying nitrate reductive potential.
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Affiliation(s)
- Craig R Anderson
- The New Zealand Institute for Plant & Food Research Limited, Lincoln Campus, Christchurch, New Zealand
| | - Michelle E Peterson
- The New Zealand Institute for Plant & Food Research Limited, Lincoln Campus, Christchurch, New Zealand
| | - Rebekah A Frampton
- The New Zealand Institute for Plant & Food Research Limited, Lincoln Campus, Christchurch, New Zealand
| | - Simon R Bulman
- The New Zealand Institute for Plant & Food Research Limited, Lincoln Campus, Christchurch, New Zealand
| | - Sandi Keenan
- The New Zealand Institute for Plant & Food Research Limited, Lincoln Campus, Christchurch, New Zealand
| | - Denis Curtin
- The New Zealand Institute for Plant & Food Research Limited, Lincoln Campus, Christchurch, New Zealand
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Xu Z, Dai X, Chai X. Effect of different carbon sources on denitrification performance, microbial community structure and denitrification genes. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 634:195-204. [PMID: 29627542 DOI: 10.1016/j.scitotenv.2018.03.348] [Citation(s) in RCA: 135] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Revised: 03/28/2018] [Accepted: 03/28/2018] [Indexed: 06/08/2023]
Abstract
Solid and liquid organic substances as carbon sources for denitrification process were deeply explored. In this study, the effect of three carbon sources, referred to as poly (3-hydroxybutyrate-co-3-hydroxyvalerate)/poly (lactic acid) (PHBV/PLA) polymer, glucose and CH3COONa, on denitrification performance, microbial community and functional genes were investigated. It was found that maximum denitrification rates of 0.37, 0.46 and 0.39gN/(L·d) were achieved in PHBV/PLA, glucose and CH3COONa supported denitrification systems, respectively. Meanwhile, Illumina MiSeq sequencing revealed that three carbon sources led to different microbial community structures. It can be seen that Brevinema/Thauera/Dechloromonas, Tolumonas/Thauera/Dechloromonas, Thauera dominated in the PHBV/PLA, glucose and CH3COONa supported denitrification systems, respectively. Transcriptome-based analysis further indicated that the glucose supported denitrification system showed the highest FPKM values (the fragments per kilobase per million mapped reads) of the genes participating in the dissimilatory nitrate reduction process, corresponding to the greatest effluent NH4+-N concentration. A better knowledge of effect of different carbon sources on denitrification process will be significant for nitrate removal in practice.
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Affiliation(s)
- Zhongshuo Xu
- College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China
| | - Xiaohu Dai
- College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China
| | - Xiaoli Chai
- College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China.
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Characterization of the quinol-dependent nitric oxide reductase from the pathogen Neisseria meningitidis, an electrogenic enzyme. Sci Rep 2018; 8:3637. [PMID: 29483528 PMCID: PMC5826923 DOI: 10.1038/s41598-018-21804-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Accepted: 02/09/2018] [Indexed: 12/01/2022] Open
Abstract
Bacterial nitric oxide reductases (NORs) catalyse the reduction of NO to N2O and H2O. NORs are found either in denitrification chains, or in pathogens where their primary role is detoxification of NO produced by the immune defense of the host. Although NORs belong to the heme-copper oxidase superfamily, comprising proton-pumping O2-reducing enzymes, the best studied NORs, cNORs (cytochrome c-dependent), are non-electrogenic. Here, we focus on another type of NOR, qNOR (quinol-dependent). Recombinant qNOR from Neisseria meningitidis, a human pathogen, purified from Escherichia coli, showed high catalytic activity and spectroscopic properties largely similar to cNORs. However, in contrast to cNOR, liposome-reconstituted qNOR showed respiratory control ratios above two, indicating that NO reduction by qNOR was electrogenic. Further, we determined a 4.5 Å crystal structure of the N. meningitidis qNOR, allowing exploration of a potential proton transfer pathway from the cytoplasm by mutagenesis. Most mutations had little effect on the activity, however the E-498 variants were largely inactive, while the corresponding substitution in cNOR was previously shown not to induce significant effects. We thus suggest that, contrary to cNOR, the N. meningitidis qNOR uses cytoplasmic protons for NO reduction. Our results allow possible routes for protons to be discussed.
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The catalytic cycle of nitrous oxide reductase - The enzyme that catalyzes the last step of denitrification. J Inorg Biochem 2017; 177:423-434. [PMID: 28927704 DOI: 10.1016/j.jinorgbio.2017.09.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 09/02/2017] [Accepted: 09/08/2017] [Indexed: 01/27/2023]
Abstract
The reduction of the potent greenhouse gas nitrous oxide requires a catalyst to overcome the large activation energy barrier of this reaction. Its biological decomposition to the inert dinitrogen can be accomplished by denitrifiers through nitrous oxide reductase, the enzyme that catalyzes the last step of the denitrification, a pathway of the biogeochemical nitrogen cycle. Nitrous oxide reductase is a multicopper enzyme containing a mixed valence CuA center that can accept electrons from small electron shuttle proteins, triggering electron flow to the catalytic sulfide-bridged tetranuclear copper "CuZ center". This enzyme has been isolated with its catalytic center in two forms, CuZ*(4Cu1S) and CuZ(4Cu2S), proven to be spectroscopic and structurally different. In the last decades, it has been a challenge to characterize the properties of this complex enzyme, due to the different oxidation states observed for each of its centers and the heterogeneity of its preparations. The substrate binding site in those two "CuZ center" forms and which is the active form of the enzyme is still a matter of debate. However, in the last years the application of different spectroscopies, together with theoretical calculations have been useful in answering these questions and in identifying intermediate species of the catalytic cycle. An overview of the spectroscopic, kinetics and structural properties of the two forms of the catalytic "CuZ center" is given here, together with the current knowledge on nitrous oxide reduction mechanism by nitrous oxide reductase and its intermediate species.
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Sun Y, De Vos P, Willems A. Nitrogen assimilation in denitrifier Bacillus azotoformans LMG 9581 T. Antonie van Leeuwenhoek 2017; 110:1613-1626. [PMID: 28726125 DOI: 10.1007/s10482-017-0911-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 07/12/2017] [Indexed: 11/27/2022]
Abstract
Until recently, it has not been generally known that some bacteria can contain the gene inventory for both denitrification and dissimilatory nitrate (NO3-)/nitrite (NO2-) reduction to ammonium (NH4+) (DNRA). Detailed studies of these microorganisms could shed light on the differentiating environmental drivers of both processes without interference of organism-specific variation. Genome analysis of Bacillus azotoformans LMG 9581T shows a remarkable redundancy of dissimilatory nitrogen reduction, with multiple copies of each denitrification gene as well as DNRA genes nrfAH, but a reduced capacity for nitrogen assimilation, with no nas operon nor amtB gene. Here, we explored nitrogen assimilation in detail using growth experiments in media with different organic and inorganic nitrogen sources at different concentrations. Monitoring of growth, NO3- NO2-, NH4+ concentration and N2O production revealed that B. azotoformans LMG 9581T could not grow with NH4+ as sole nitrogen source and confirmed the hypothesis of reduced nitrogen assimilation pathways. However, NH4+ could be assimilated and contributed up to 50% of biomass if yeast extract was also provided. NH4+ also had a significant but concentration-dependent influence on growth rate. The mechanisms behind these observations remain to be resolved but hypotheses for this deficiency in nitrogen assimilation are discussed. In addition, in all growth conditions tested a denitrification phenotype was observed, with all supplied NO3- converted to nitrous oxide (N2O).
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Affiliation(s)
- Yihua Sun
- Laboratory of Microbiology, Ghent University, K.L. Ledeganckstraat 35, 9000, Ghent, Belgium
| | - Paul De Vos
- Laboratory of Microbiology, Ghent University, K.L. Ledeganckstraat 35, 9000, Ghent, Belgium
| | - Anne Willems
- Laboratory of Microbiology, Ghent University, K.L. Ledeganckstraat 35, 9000, Ghent, Belgium.
- Laboratory of Microbiology (LM-UGent), Department of Biochemistry and Microbiology, Ghent University, K.L. Ledeganckstraat 35, 9000, Ghent, Belgium.
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Characterization and Potential Applications of a Selenium Nanoparticle Producing and Nitrate Reducing Bacterium Bacillus oryziterrae sp. nov. Sci Rep 2016; 6:34054. [PMID: 27677458 PMCID: PMC5039721 DOI: 10.1038/srep34054] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Accepted: 09/02/2016] [Indexed: 01/29/2023] Open
Abstract
A novel nitrate- and selenite reducing bacterium strain ZYKT was isolated from a rice paddy soil in Dehong, Yunnan, China. Strain ZYKT is a facultative anaerobe and grows in up to 150, 000 ppm O2. The comparative genomics analysis of strain ZYKT implies that it shares more orthologues with B. subtilis subsp. subtilis NCIB 3610T (ANIm values, 85.4–86.7%) than with B. azotoformans NBRC 15712T (ANIm values, 84.4–84.7%), although B. azotoformans NBRC 15712T (96.3% 16S rRNA gene sequence similarity) is the closest Bacillus species according to 16S rRNA gene comparison. The major cellular fatty acids of strain ZYKT were iso-C14:0 (17.8%), iso-C15:0 (17.8%), and C16:0 (32.0%). The polar lipid profile consisted of phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol and an unidentified aminophospholipid. Based on physiological, biochemical and genotypic properties, the strain was considered to represent a novel species of the genus Bacillus, for which the name Bacillus oryziterrae sp. nov. is proposed. The type strain is ZYKT (=DSM 26460T =CGMCC 1.5179T). Strain ZYKT can reduce nitrate to nitrite and ammonium and possesses metabolic genes for nitrate reduction including nar, nap and nrf. Biogenic selenium nanoparticles of strain ZYKT show a narrow size distribution and agree with the gaussian distribution. These selenium nanoparticles show significant dose-dependent inhibition of the lung cancer cell line H157, which suggests potential for application in cancer therapy.
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Highly diverse nirK genes comprise two major clades that harbour ammonium-producing denitrifiers. BMC Genomics 2016; 17:155. [PMID: 26923558 PMCID: PMC4770552 DOI: 10.1186/s12864-016-2465-0] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 02/12/2016] [Indexed: 01/09/2023] Open
Abstract
Background Copper dependent nitrite reductase, NirK, catalyses the key step in denitrification, i.e. nitrite reduction to nitric oxide. Distinct structural NirK classes and phylogenetic clades of NirK-type denitrifiers have previously been observed based on a limited set of NirK sequences, however, their environmental distribution or ecological strategies are currently unknown. In addition, environmental nirK-type denitrifiers are currently underestimated in PCR-dependent surveys due to primer coverage limitations that can be attributed to their broad taxonomic diversity and enormous nirK sequence divergence. Therefore, we revisited reported analyses on partial NirK sequences using a taxonomically diverse, full-length NirK sequence dataset. Results Division of NirK sequences into two phylogenetically distinct clades was confirmed, with Clade I mainly comprising Alphaproteobacteria (plus some Gamma- and Betaproteobacteria) and Clade II harbouring more diverse taxonomic groups like Archaea, Bacteroidetes, Chloroflexi, Gemmatimonadetes, Nitrospirae, Firmicutes, Actinobacteria, Planctomycetes and Proteobacteria (mainly Beta and Gamma). Failure of currently available primer sets to target diverse NirK-type denitrifiers in environmental surveys could be attributed to mismatches over the whole length of the primer binding regions including the 3′ site, with Clade II sequences containing higher sequence divergence than Clade I sequences. Simultaneous presence of both the denitrification and DNRA pathway could be observed in 67 % of all NirK-type denitrifiers. Conclusion The previously reported division of NirK into two distinct phylogenetic clades was confirmed using a taxonomically diverse set of full-length NirK sequences. Enormous sequence divergence of nirK gene sequences, probably due to variable nirK evolutionary trajectories, will remain an issue for covering diverse NirK-type denitrifiers in amplicon-based environmental surveys. The potential of a single organism to partition nitrate to either denitrification or dissimilatory nitrate reduction to ammonium appeared to be more widespread than originally anticipated as more than half of all NirK-type denitrifiers were shown to contain both pathways in their genome. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-2465-0) contains supplementary material, which is available to authorized users.
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Sun Y, De Vos P, Heylen K. Nitrous oxide emission by the non-denitrifying, nitrate ammonifier Bacillus licheniformis. BMC Genomics 2016; 17:68. [PMID: 26786044 PMCID: PMC4719734 DOI: 10.1186/s12864-016-2382-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Accepted: 01/06/2016] [Indexed: 02/08/2023] Open
Abstract
Background Firmicutes have the capacity to remove excess nitrate from the environment via either denitrification, dissimilatory nitrate reduction to ammonium or both. The recent renewed interest in their nitrogen metabolism has revealed many interesting features, the most striking being their wide variety of dissimilatory nitrate reduction pathways. In the present study, nitrous oxide production from Bacillus licheniformis, a ubiquitous Gram-positive, spore-forming species with many industrial applications, is investigated. Results B. licheniformis has long been considered a denitrifier but physiological experiments on three different strains demonstrated that nitrous oxide is not produced from nitrate in stoichiometric amounts, rather ammonium is the most important end-product, produced during fermentation. Significant strain dependency in end-product ratios, attributed to nitrite and ammonium, and medium dependency in nitrous oxide production were also observed. Genome analyses confirmed the lack of a nitrite reductase to nitric oxide, the key enzyme of denitrification. Based on the gene inventory and building on knowledge from other non-denitrifying nitrous oxide emitters, hypothetical pathways for nitrous oxide production, involving NarG, NirB, qNor and Hmp, are proposed. In addition, all publically available genomes of B. licheniformis demonstrated similar gene inventories, with specific duplications of the nar operon, narK and hmp genes as well as NarG phylogeny supporting the evolutionary separation of previously described distinct BALI1 and BALI2 lineages. Conclusions Using physiological and genomic data we have demonstrated that the common soil bacterium B. licheniformis does not denitrify but is capable of fermentative dissimilatory nitrate/nitrite reduction to ammonium (DNRA) with concomitant production of N2O. Considering its ubiquitous nature and non-fastidious growth in the lab, B. licheniformis is a suitable candidate for further exploration of the actual mechanism of N2O production in DNRA bacteria and its relevance in situ. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-2382-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Yihua Sun
- Department of Biochemistry and Microbiology, Laboratory of Microbiology, (LM-UGent), University of Ghent, K.L. Ledeganckstraat 35, 9000, Gent, Belgium.
| | - Paul De Vos
- Department of Biochemistry and Microbiology, Laboratory of Microbiology, (LM-UGent), University of Ghent, K.L. Ledeganckstraat 35, 9000, Gent, Belgium. .,BCCM/LMG Bacteria Collection, K.L. Ledeganckstraat 35, 9000, Gent, Belgium.
| | - Kim Heylen
- Department of Biochemistry and Microbiology, Laboratory of Microbiology, (LM-UGent), University of Ghent, K.L. Ledeganckstraat 35, 9000, Gent, Belgium.
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Torres M, Simon J, Rowley G, Bedmar E, Richardson D, Gates A, Delgado M. Nitrous Oxide Metabolism in Nitrate-Reducing Bacteria: Physiology and Regulatory Mechanisms. Adv Microb Physiol 2016; 68:353-432. [PMID: 27134026 DOI: 10.1016/bs.ampbs.2016.02.007] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Nitrous oxide (N2O) is an important greenhouse gas (GHG) with substantial global warming potential and also contributes to ozone depletion through photochemical nitric oxide (NO) production in the stratosphere. The negative effects of N2O on climate and stratospheric ozone make N2O mitigation an international challenge. More than 60% of global N2O emissions are emitted from agricultural soils mainly due to the application of synthetic nitrogen-containing fertilizers. Thus, mitigation strategies must be developed which increase (or at least do not negatively impact) on agricultural efficiency whilst decrease the levels of N2O released. This aim is particularly important in the context of the ever expanding population and subsequent increased burden on the food chain. More than two-thirds of N2O emissions from soils can be attributed to bacterial and fungal denitrification and nitrification processes. In ammonia-oxidizing bacteria, N2O is formed through the oxidation of hydroxylamine to nitrite. In denitrifiers, nitrate is reduced to N2 via nitrite, NO and N2O production. In addition to denitrification, respiratory nitrate ammonification (also termed dissimilatory nitrate reduction to ammonium) is another important nitrate-reducing mechanism in soil, responsible for the loss of nitrate and production of N2O from reduction of NO that is formed as a by-product of the reduction process. This review will synthesize our current understanding of the environmental, regulatory and biochemical control of N2O emissions by nitrate-reducing bacteria and point to new solutions for agricultural GHG mitigation.
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Decleyre H, Heylen K, Van Colen C, Willems A. Dissimilatory nitrogen reduction in intertidal sediments of a temperate estuary: small scale heterogeneity and novel nitrate-to-ammonium reducers. Front Microbiol 2015; 6:1124. [PMID: 26528270 PMCID: PMC4604302 DOI: 10.3389/fmicb.2015.01124] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 09/28/2015] [Indexed: 11/13/2022] Open
Abstract
The estuarine nitrogen cycle can be substantially altered due to anthropogenic activities resulting in increased amounts of inorganic nitrogen (mainly nitrate). In the past, denitrification was considered to be the main ecosystem process removing reactive nitrogen from the estuarine ecosystem. However, recent reports on the contribution of dissimilatory nitrate reduction to ammonium (DNRA) to nitrogen removal in these systems indicated a similar or higher importance, although the ratio between both processes remains ambiguous. Compared to denitrification, DNRA has been underexplored for the last decades and the key organisms carrying out the process in marine environments are largely unknown. Hence, as a first step to better understand the interplay between denitrification, DNRA and reduction of nitrate to nitrite in estuarine sediments, nitrogen reduction potentials were determined in sediments of the Paulina polder mudflat (Westerschelde estuary). We observed high variability in dominant nitrogen removing processes over a short distance (1.6 m), with nitrous oxide, ammonium and nitrite production rates differing significantly between all sampling sites. Denitrification occurred at all sites, DNRA was either the dominant process (two out of five sites) or absent, while nitrate reduction to nitrite was observed in most sites but never dominant. In addition, novel nitrate-to-ammonium reducers assigned to Thalassospira, Celeribacter, and Halomonas, for which DNRA was thus far unreported, were isolated, with DNRA phenotype reconfirmed through nrfA gene amplification. This study demonstrates high small scale heterogeneity among dissimilatory nitrate reduction processes in estuarine sediments and provides novel marine DNRA organisms that represent valuable alternatives to the current model organisms.
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Affiliation(s)
- Helen Decleyre
- Laboratory of Microbiology (LM-UGent), Department of Biochemistry and Microbiology, Ghent University Ghent, Belgium
| | - Kim Heylen
- Laboratory of Microbiology (LM-UGent), Department of Biochemistry and Microbiology, Ghent University Ghent, Belgium
| | - Carl Van Colen
- Marine Biology Research Group, Department of Biology, Ghent University Ghent, Belgium
| | - Anne Willems
- Laboratory of Microbiology (LM-UGent), Department of Biochemistry and Microbiology, Ghent University Ghent, Belgium
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Al-Attar S, de Vries S. An electrogenic nitric oxide reductase. FEBS Lett 2015; 589:2050-7. [PMID: 26149211 DOI: 10.1016/j.febslet.2015.06.033] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Revised: 06/24/2015] [Accepted: 06/24/2015] [Indexed: 10/23/2022]
Abstract
Nitric oxide reductases (Nors) are members of the heme-copper oxidase superfamily that reduce nitric oxide (NO) to nitrous oxide (N₂O). In contrast to the proton-pumping cytochrome oxidases, Nors studied so far have neither been implicated in proton pumping nor have they been experimentally established as electrogenic. The copper-A-dependent Nor from Bacillus azotoformans uses cytochrome c₅₅₁ as electron donor but lacks menaquinol activity, in contrast to our earlier report (Suharti et al., 2001). Employing reduced phenazine ethosulfate (PESH) as electron donor, the main NO reduction pathway catalyzed by Cu(A)Nor reconstituted in liposomes involves transmembrane cycling of the PES radical. We show that Cu(A)Nor reconstituted in liposomes generates a proton electrochemical gradient across the membrane similar in magnitude to cytochrome aa₃, highlighting that bacilli using Cu(A)Nor can exploit NO reduction for increased cellular ATP production compared to organisms using cNor.
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Affiliation(s)
- Sinan Al-Attar
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC, The Netherlands
| | - Simon de Vries
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC, The Netherlands.
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Tsuge T, Hyakutake M, Mizuno K. Class IV polyhydroxyalkanoate (PHA) synthases and PHA-producing Bacillus. Appl Microbiol Biotechnol 2015; 99:6231-40. [PMID: 26135986 DOI: 10.1007/s00253-015-6777-9] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2015] [Revised: 06/11/2015] [Accepted: 06/17/2015] [Indexed: 12/28/2022]
Abstract
This review highlights the recent investigations of class IV polyhydroxyalkanoate (PHA) synthases, the newest classification of PHA synthases. Class IV synthases are prevalent in organisms of the Bacillus genus and are composed of a catalytic subunit PhaC (approximately 40 kDa), which has a PhaC box sequence ([GS]-X-C-X-[GA]-G) at the active site, and a second subunit PhaR (approximately 20 kDa). The representative PHA-producing Bacillus strains are Bacillus megaterium and Bacillus cereus; the nucleotide sequence of phaC and the genetic organization of the PHA biosynthesis gene locus are somewhat different between these two strains. It is generally considered that class IV synthases favor short-chain-length monomers such as 3-hydroxybutyrate (C4) and 3-hydroxyvalerate (C5) for polymerization, but can polymerize some unusual monomers as minor components. In Escherichia coli expressing PhaRC from B. cereus YB-4, the biosynthesized PHA undergoes synthase-catalyzed alcoholytic cleavage using endogenous and exogenous alcohols. This alcoholysis is thought to be shared among class IV synthases, and this reaction is useful not only for the regulation of PHA molecular weight but also for the modification of the PHA carboxy terminus. The novel properties of class IV synthases will open up the possibility for the design of new PHA materials.
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Affiliation(s)
- Takeharu Tsuge
- Department of Innovative and Engineered Materials, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama, 226-8502, Japan,
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36
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Nielsen M, Schreiber L, Finster K, Schramm A. Draft genome sequence of Bacillus azotoformans MEV2011, a (Co-) denitrifying strain unable to grow with oxygen. Stand Genomic Sci 2015; 9:23. [PMID: 25685261 PMCID: PMC4322954 DOI: 10.1186/1944-3277-9-23] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Accepted: 11/18/2014] [Indexed: 11/24/2022] Open
Abstract
Bacillus azotoformans MEV2011, isolated from soil, is a microaerotolerant obligate denitrifier, which can also produce N2 by co-denitrification. Oxygen is consumed but not growth-supportive. The draft genome has a size of 4.7 Mb and contains key genes for both denitrification and dissimilatory nitrate reduction to ammonium.
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Affiliation(s)
- Maja Nielsen
- Section for Microbiology, Department of Bioscience, Aarhus University, Aarhus, Denmark
| | - Lars Schreiber
- Center for Geomicrobiology, Department of Bioscience, Aarhus University, Aarhus, Denmark
| | - Kai Finster
- Section for Microbiology, Department of Bioscience, Aarhus University, Aarhus, Denmark.,Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark
| | - Andreas Schramm
- Section for Microbiology, Department of Bioscience, Aarhus University, Aarhus, Denmark.,Center for Geomicrobiology, Department of Bioscience, Aarhus University, Aarhus, Denmark
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37
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Nielsen M, Schreiber L, Finster K, Schramm A. Draft genome sequence of Bacillus azotoformans MEV2011, a (Co-) denitrifying strain unable to grow with oxygen. Stand Genomic Sci 2015; 10:4. [PMID: 26413196 PMCID: PMC4582720 DOI: 10.1186/1944-3277-10-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Accepted: 11/18/2014] [Indexed: 11/24/2022] Open
Abstract
Bacillus azotoformans MEV2011, isolated from soil, is a microaerotolerant obligate denitrifier, which can also produce N2 by co-denitrification. Oxygen is consumed but not growth-supportive. The draft genome has a size of 4.7 Mb and contains key genes for both denitrification and dissimilatory nitrate reduction to ammonium.
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Reimann J, Jetten MSM, Keltjens JT. Metal enzymes in "impossible" microorganisms catalyzing the anaerobic oxidation of ammonium and methane. Met Ions Life Sci 2015; 15:257-313. [PMID: 25707470 DOI: 10.1007/978-3-319-12415-5_7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Ammonium and methane are inert molecules and dedicated enzymes are required to break up the N-H and C-H bonds. Until recently, only aerobic microorganisms were known to grow by the oxidation of ammonium or methane. Apart from respiration, oxygen was specifically utilized to activate the inert substrates. The presumed obligatory need for oxygen may have resisted the search for microorganisms that are capable of the anaerobic oxidation of ammonium and of methane. However extremely slowly growing, these "impossible" organisms exist and they found other means to tackle ammonium and methane. Anaerobic ammonium-oxidizing (anammox) bacteria use the oxidative power of nitric oxide (NO) by forging this molecule to ammonium, thereby making hydrazine (N2H4). Nitrite-dependent anaerobic methane oxidizers (N-DAMO) again take advantage of NO, but now apparently disproportionating the compound into dinitrogen and dioxygen gas. This intracellularly produced dioxygen enables N-DAMO bacteria to adopt an aerobic mechanism for methane oxidation.Although our understanding is only emerging how hydrazine synthase and the NO dismutase act, it seems clear that reactions fully rely on metal-based catalyses known from other enzymes. Metal-dependent conversions not only hold for these key enzymes, but for most other reactions in the central catabolic pathways, again supported by well-studied enzymes from model organisms, but adapted to own specific needs. Remarkably, those accessory catabolic enzymes are not unique for anammox bacteria and N-DAMO. Close homologs are found in protein databases where those homologs derive from (partly) known, but in most cases unknown species that together comprise an only poorly comprehended microbial world.
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Affiliation(s)
- Joachim Reimann
- Department of Microbiology, Institute of Wetland and Water Research (IWWR), Radboud University of Nijmegen, Heyendaalseweg 135, 6525AJ, Nijmegen, The Netherlands,
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Transcription of the lysine-2,3-aminomutase gene in the kam locus of Bacillus thuringiensis subsp. kurstaki HD73 is controlled by both σ54 and σK factors. J Bacteriol 2014; 196:2934-43. [PMID: 24914178 DOI: 10.1128/jb.01675-14] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Lysine 2,3-aminomutase (KAM; EC 5.4.3.2) catalyzes the interconversion of l-lysine and l-β-lysine. The transcription and regulation of the kam locus, including lysine-2,3-aminomutase-encoding genes, in Bacillus thuringiensis were analyzed in this study. Reverse transcription-PCR (RT-PCR) analysis revealed that this locus forms two operons: yodT (yodT-yodS-yodR-yodQ-yodP-kamR) and kamA (kamA-yokU-yozE). The transcriptional start sites (TSSs) of the kamA gene were determined using 5' rapid amplification of cDNA ends (RACE). A typical -12/-24 σ(54) binding site was identified in the promoter PkamA, which is located upstream of the kamA gene TSS. A β-galactosidase assay showed that PkamA, which directs the transcription of the kamA operon, is controlled by the σ(54) factor and is activated through the σ(54)-dependent transcriptional regulator KamR. The kamA operon is also controlled by σ(K) and regulated by the GerE protein in the late stage of sporulation. kamR and kamA mutants were prepared by homologous recombination to examine the role of the kam locus. The results showed that the sporulation rate in B. thuringiensis HD(ΔkamR) was slightly decreased compared to that in HD73, whereas that in HD(ΔkamA) was similar to that in HD73. This means that other genes regulated by KamR are important for sporulation.
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Verbaendert I, Hoefman S, Boeckx P, Boon N, De Vos P. Primers for overlooked nirK, qnorB, and nosZ genes of thermophilic Gram-positive denitrifiers. FEMS Microbiol Ecol 2014; 89:162-80. [PMID: 24784780 DOI: 10.1111/1574-6941.12346] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Revised: 04/03/2014] [Accepted: 04/10/2014] [Indexed: 12/16/2022] Open
Abstract
Although efforts have been made the past few years, knowledge on genomic and phenotypic diversity and occurrence of the denitrification ability in Gram-positive bacteria are still fragmentary. Many environmental monitoring approaches have used nir, nor, and nos genes as marker genes for detection of denitrification or denitrifying bacteria. However, primers used in these methods often fail to detect the genes in specific bacterial taxa, such as Gram-positive denitrifiers. In this study, novel primer sets specifically targeting nirK, qnorB, and nosZ genes of the Firmicute genus Geobacillus were developed by genomic mining and tested in parallel with commonly used primers on a set of phylogenetically closely related denitrifying geobacilli. Novel nirK and qnorB sequences were recovered from all strains tested, whereas nosZ was detected in part of the strain set, which was in agreement with observed phenotypes. Interspecies and modest intraspecies variations in amplified fragment length polymorphism (AFLP) patterns were observed, verifying presence of genomic variation within the strain set. Our study shows that closely related Gram-positive denitrifiers may differ in denitrification phenotype and genotype. But foremost, novel primers targeting very divergent nirK, qnorB, and nosZ gene sequences of Gram-positive denitrifiers, are now available for cultivation-independent environmental surveys.
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Affiliation(s)
- Ines Verbaendert
- Laboratory of Microbiology (LM-UGent), Department of Biochemistry and Microbiology, Ghent University, Gent, Belgium
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Mania D, Heylen K, van Spanning RJM, Frostegård Å. The nitrate-ammonifying andnosZ-carrying bacteriumBacillus viretiis a potent source and sink for nitric and nitrous oxide under high nitrate conditions. Environ Microbiol 2014; 16:3196-210. [DOI: 10.1111/1462-2920.12478] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 03/13/2014] [Accepted: 03/24/2014] [Indexed: 11/30/2022]
Affiliation(s)
- Daniel Mania
- Department of Chemistry, Biotechnology and Food Science; Norwegian University of Life Science; Ås Norway
| | - Kim Heylen
- Laboratory of Microbiology; Department of Biochemistry and Microbiology; University of Ghent; Gent Belgium
| | - Rob J. M. van Spanning
- Department of Molecular Cell Biology; Faculty of Earth and Life Science; VU University; Amsterdam The Netherlands
| | - Åsa Frostegård
- Department of Chemistry, Biotechnology and Food Science; Norwegian University of Life Science; Ås Norway
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Luckmann M, Mania D, Kern M, Bakken LR, Frostegård Å, Simon J. Production and consumption of nitrous oxide in nitrate-ammonifying Wolinella succinogenes cells. MICROBIOLOGY-SGM 2014; 160:1749-1759. [PMID: 24781903 DOI: 10.1099/mic.0.079293-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Global warming is moving more and more into the public consciousness. Besides the commonly mentioned carbon dioxide and methane, nitrous oxide (N2O) is a powerful greenhouse gas in addition to its contribution to depletion of stratospheric ozone. The increasing concern about N2O emission has focused interest on underlying microbial energy-converting processes and organisms harbouring N2O reductase (NosZ), such as denitrifiers and ammonifiers of nitrate and nitrite. Here, the epsilonproteobacterial model organism Wolinella succinogenes is investigated with regard to its capacity to produce and consume N2O during growth by anaerobic nitrate ammonification. This organism synthesizes an unconventional cytochrome c nitrous oxide reductase (cNosZ), which is encoded by the first gene of an atypical nos gene cluster. However, W. succinogenes lacks a nitric oxide (NO)-producing nitrite reductase of the NirS- or NirK-type as well as an NO reductase of the Nor-type. Using a robotized incubation system, the wild-type strain and suitable mutants of W. succinogenes that either produced or lacked cNosZ were analysed as to their production of NO, N2O and N2 in both nitrate-sufficient and nitrate-limited growth medium using formate as electron donor. It was found that cells growing in nitrate-sufficient medium produced small amounts of N2O, which derived from nitrite and, most likely, from the presence of NO. Furthermore, cells employing cNosZ were able to reduce N2O to N2. This reaction, which was fully inhibited by acetylene, was also observed after adding N2O to the culture headspace. The results indicate that W. succinogenes cells are competent in N2O and N2 production despite being correctly grouped as respiratory nitrate ammonifiers. N2O production is assumed to result from NO detoxification and nitrosative stress defence, while N2O serves as a terminal electron acceptor in anaerobic respiration. The ecological implications of these findings are discussed.
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Affiliation(s)
- Monique Luckmann
- Microbial Energy Conversion and Biotechnology, Department of Biology, Technische Universität Darmstadt, Schnittspahnstraße 10, 64287 Darmstadt, Germany
| | - Daniel Mania
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Chr Falsens vei 1, N1432 Ås, Norway
| | - Melanie Kern
- Microbial Energy Conversion and Biotechnology, Department of Biology, Technische Universität Darmstadt, Schnittspahnstraße 10, 64287 Darmstadt, Germany
| | - Lars R Bakken
- Department of Plant and Environmental Sciences, Norwegian University of Life Sciences, PO Box 5003, N1432 Ås, Norway
| | - Åsa Frostegård
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Chr Falsens vei 1, N1432 Ås, Norway
| | - Jörg Simon
- Microbial Energy Conversion and Biotechnology, Department of Biology, Technische Universität Darmstadt, Schnittspahnstraße 10, 64287 Darmstadt, Germany
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Abstract
The global biogeochemical nitrogen cycle is essential for life on Earth. Many of the underlying biotic reactions are catalyzed by a multitude of prokaryotic and eukaryotic life forms whereas others are exclusively carried out by microorganisms. The last century has seen the rise of a dramatic imbalance in the global nitrogen cycle due to human behavior that was mainly caused by the invention of the Haber-Bosch process. Its main product, ammonia, is a chemically reactive and biotically favorable form of bound nitrogen. The anthropogenic supply of reduced nitrogen to the biosphere in the form of ammonia, for example during environmental fertilization, livestock farming, and industrial processes, is mandatory in feeding an increasing world population. In this chapter, environmental ammonia pollution is linked to the activity of microbial metalloenzymes involved in respiratory energy metabolism and bioenergetics. Ammonia-producing multiheme cytochromes c are discussed as paradigm enzymes.
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Affiliation(s)
- Jörg Simon
- Microbial Energy Conversion and Biotechnology, Department of Biology, Technische Universität Darmstadt, Schnittspahnstrasse 10, D-64287, Darmstadt, Germany,
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