1
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Yang L, Han P, Wang Q, Lin H, Wang D, Mao J, Qi W, Bai Y, Qu J. Disinfectant-induced ammonia oxidation disruption in microbial N-cycling process in aquatic ecosystem after the COVID-19 outbreak. WATER RESEARCH 2024; 258:121761. [PMID: 38749183 DOI: 10.1016/j.watres.2024.121761] [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: 03/04/2024] [Revised: 04/19/2024] [Accepted: 05/08/2024] [Indexed: 06/16/2024]
Abstract
Anthropogenic activities significantly impact the elemental cycles in aquatic ecosystems, with the N-cycling playing a critical role in potential nutrient turnover and substance cycling. We hypothesized that measures to prevent COVID-19 transmission profoundly altered the nitrogen cycle in riverine ecosystems. To investigate this, we re-analyzed metagenomic data and identified 60 N-cycling genes and 21 host metagenomes from four urban reaches (one upstream city, Wuhan, and two downstream cities) along the Yangtze River. Our analyses revealed a marked decrease in the abundance of bacterial ammonia monooxygenase genes, as well as in the host, ammonia-oxidizing autotrophic Nitrosomonas, followed by a substantial recovery post-pandemic. We posited that discharge of sodium hypochlorite (NaOCl) disinfectant may be a primary factor in the reduction of N-cycling process. To test this hypothesis, we exposed pure cultures of Nitrosomonas europaea to NaOCl to explore the microbial stress response. Results indicated that NaOCl exposure rapidly compromised the cell structure and inhibited ammonia oxidation of N. europaea, likely due to oxidative stress damage and reduced expression of nitrogen metabolism-related ammonia monooxygenase. Using the functional tagging technique, we determined that NaOCl directly destroyed the ammonia monooxygenase protein and DNA structure. This study highlights the negative impacts of chlorine disinfectants on the function of aquatic ecosystems and elucidates potential mechanisms of action.
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Affiliation(s)
- Lutong Yang
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; University of Chinese Academy of Science, Beijing, 100049, China
| | - Ping Han
- Key Laboratory of Geographic Information Science (Ministry of Education), School of Geographic Sciences, East China Normal University, 500 Dongchuan Road, Shanghai, 200241, China; State Key Laboratory of Estuarine and Coastal Research, East China Normal University, 500 Dongchuan Road, Shanghai, 200241, China
| | - Qiaojuan Wang
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; University of Chinese Academy of Science, Beijing, 100049, China
| | - Hui Lin
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; University of Chinese Academy of Science, Beijing, 100049, China
| | - Donglin Wang
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China
| | - Jie Mao
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China
| | - Weixiao Qi
- Center for Water and Ecology, Tsinghua University, Beijing, 100084, China
| | - Yaohui Bai
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China.
| | - Jiuhui Qu
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China
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2
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Beeckman F, Annetta L, Corrochano-Monsalve M, Beeckman T, Motte H. Enhancing agroecosystem nitrogen management: microbial insights for improved nitrification inhibition. Trends Microbiol 2024; 32:590-601. [PMID: 37973432 DOI: 10.1016/j.tim.2023.10.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2023] [Revised: 10/19/2023] [Accepted: 10/20/2023] [Indexed: 11/19/2023]
Abstract
Nitrification is a key microbial process in the nitrogen (N) cycle that converts ammonia to nitrate. Excessive nitrification, typically occurring in agroecosystems, has negative environmental impacts, including eutrophication and greenhouse gas emissions. Nitrification inhibitors (NIs) are widely used to manage N in agricultural systems by reducing nitrification rates and improving N use efficiency. However, the effectiveness of NIs can vary depending on the soil conditions, which, in turn, affect the microbial community and the balance between different functional groups of nitrifying microorganisms. Understanding the mechanisms underlying the effectiveness of NIs, and how this is affected by the soil microbial communities or abiotic factors, is crucial for promoting sustainable fertilizer practices. Therefore, this review examines the different types of NIs and how abiotic parameters can influence the nitrifying community, and, therefore, the efficacy of NIs. By discussing the latest research in this field, we provide insights that could facilitate the development of more targeted, efficient, or complementary NIs that improve the application of NIs for sustainable management practices in agroecosystems.
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Affiliation(s)
- Fabian Beeckman
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 71, 9052 Ghent, Belgium; VIB Center for Plant Systems Biology, Technologiepark 71, 9052 Ghent, Belgium
| | - Laure Annetta
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 71, 9052 Ghent, Belgium; VIB Center for Plant Systems Biology, Technologiepark 71, 9052 Ghent, Belgium
| | - Mario Corrochano-Monsalve
- Departamento de Genética, Antropología Física y Fisiología Animal, Facultad de Ciencia y Tecnología, Universidad del País Vasco (UPV/EHU), Leioa, Spain; Instituto Multidisciplinar Para el Estudio del Medio 'Ramon Margalef', Universidad de Alicante, Carretera de San Vicente del Raspeig s/n, 03690 San Vicente del Raspeig, Spain
| | - Tom Beeckman
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 71, 9052 Ghent, Belgium; VIB Center for Plant Systems Biology, Technologiepark 71, 9052 Ghent, Belgium
| | - Hans Motte
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 71, 9052 Ghent, Belgium; VIB Center for Plant Systems Biology, Technologiepark 71, 9052 Ghent, Belgium.
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3
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Skinner J, Delgado AG, Hyman M, Chu MYJ. Implementation of in situ aerobic cometabolism for groundwater treatment: State of the knowledge and important factors for field operation. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 925:171667. [PMID: 38485017 DOI: 10.1016/j.scitotenv.2024.171667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Revised: 03/04/2024] [Accepted: 03/10/2024] [Indexed: 03/23/2024]
Abstract
In situ aerobic cometabolism of groundwater contaminants has been demonstrated to be a valuable bioremediation technology to treat many legacy and emerging contaminants in dilute plumes. Several well-designed and documented field studies have shown that this technology can concurrently treat multiple contaminants and reach very low cleanup goals. Fundamentally different from metabolism-based biodegradation of contaminants, microorganisms that cometabolically degrade contaminants do not obtain sufficient carbon and energy from the degradation process to support their growth and require an exogenous growth supporting primary substrate. Successful applications of aerobic cometabolic treatment therefore require special considerations beyond conventional in situ bioremediation, such as competitive inhibition between growth-supporting primary substrate(s) and contaminant non-growth substrates, toxic effects resulting from contaminant degradation, and differences in microbial population dynamics exhibited by biostimulated indigenous consortia versus bioaugmentation cultures. This article first provides a general review of microbiological factors that are likely to affect the rate of aerobic cometabolic biodegradation. We subsequently review fourteen well documented field-scale aerobic cometabolic bioremediation studies and summarize the underlying microbiological factors that may affect the performance observed in these field studies. The combination of microbiological and engineering principles gained from field testing leads to insights and recommendations on planning, design, and operation of an in situ aerobic cometabolic treatment system. With a vision of more aerobic cometabolic treatments being considered to tackle large, dilute plumes, we present several novel topics and future research directions that can potentially enhance technology development and foster success in implementing this technology for environmental restoration.
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Affiliation(s)
- Justin Skinner
- Biodesign Swette Center for Environmental Biotechnology, Arizona State University, 1001 S McAllister Ave, Tempe, AZ 85281, USA; School of Sustainable Engineering and the Built Environment, Arizona State University, 660 S College Ave, Tempe, AZ 85281, USA; Engineering Research Center for Bio-mediated and Bio-inspired Geotechnics (CBBG), Arizona State University, 650 E Tyler Mall, Tempe, AZ 85281, USA; Andrews Engineering, Inc., 3300 Ginger Creek Drive, Springfield, IL 62711, USA
| | - Anca G Delgado
- Biodesign Swette Center for Environmental Biotechnology, Arizona State University, 1001 S McAllister Ave, Tempe, AZ 85281, USA; School of Sustainable Engineering and the Built Environment, Arizona State University, 660 S College Ave, Tempe, AZ 85281, USA; Engineering Research Center for Bio-mediated and Bio-inspired Geotechnics (CBBG), Arizona State University, 650 E Tyler Mall, Tempe, AZ 85281, USA
| | - Michael Hyman
- Department of Plant and Microbial Biology, North Carolina State University, Thomas Hall 4545, 112 Derieux Place, Raleigh, NC 27607, USA
| | - Min-Ying Jacob Chu
- Haley & Aldrich Inc., 400 E Van Buren St, Ste 545, Phoenix, AZ 85004, USA.
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4
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Skinner JP, Palar S, Allen C, Raderstorf A, Blake P, Morán Reyes A, Berg RN, Muse C, Robles A, Hamdan N, Chu MY, Delgado AG. Acetylene Tunes Microbial Growth During Aerobic Cometabolism of Trichloroethene. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:6274-6283. [PMID: 38531380 PMCID: PMC11008246 DOI: 10.1021/acs.est.3c08068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 02/28/2024] [Accepted: 02/29/2024] [Indexed: 03/28/2024]
Abstract
Microbial aerobic cometabolism is a possible treatment approach for large, dilute trichloroethene (TCE) plumes at groundwater contaminated sites. Rapid microbial growth and bioclogging pose a persistent problem in bioremediation schemes. Bioclogging reduces soil porosity and permeability, which negatively affects substrate distribution and contaminant treatment efficacy while also increasing the operation and maintenance costs of bioremediation. In this study, we evaluated the ability of acetylene, an oxygenase enzyme-specific inhibitor, to decrease biomass production while maintaining aerobic TCE cometabolism capacity upon removal of acetylene. We first exposed propane-metabolizing cultures (pure and mixed) to 5% acetylene (v v-1) for 1, 2, 4, and 8 d and we then verified TCE aerobic cometabolic activity. Exposure to acetylene overall decreased biomass production and TCE degradation rates while retaining the TCE degradation capacity. In the mixed culture, exposure to acetylene for 1-8 d showed minimal effects on the composition and relative abundance of TCE cometabolizing bacterial taxa. TCE aerobic cometabolism and incubation conditions exerted more notable effects on microbial ecology than did acetylene. Acetylene appears to be a viable approach to control biomass production that may lessen the likelihood of bioclogging during TCE cometabolism. The findings from this study may lead to advancements in aerobic cometabolism remediation technologies for dilute plumes.
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Affiliation(s)
- Justin P. Skinner
- Biodesign
Swette Center for Environmental Biotechnology, Arizona State University, Tempe, Arizona 85287, United States
- School
of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, Arizona 85281, United States
- Engineering
Research Center for Bio-mediated and Bio-inspired Geotechnics (CBBG), Arizona State University, 650 E Tyler Mall, Tempe, Arizona 85281, United States
| | - Skye Palar
- Biodesign
Swette Center for Environmental Biotechnology, Arizona State University, Tempe, Arizona 85287, United States
- School
of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, Arizona 85281, United States
- Engineering
Research Center for Bio-mediated and Bio-inspired Geotechnics (CBBG), Arizona State University, 650 E Tyler Mall, Tempe, Arizona 85281, United States
| | - Channing Allen
- Biodesign
Swette Center for Environmental Biotechnology, Arizona State University, Tempe, Arizona 85287, United States
- School
of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, Arizona 85281, United States
- Engineering
Research Center for Bio-mediated and Bio-inspired Geotechnics (CBBG), Arizona State University, 650 E Tyler Mall, Tempe, Arizona 85281, United States
| | - Alia Raderstorf
- Biodesign
Swette Center for Environmental Biotechnology, Arizona State University, Tempe, Arizona 85287, United States
- School
of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, Arizona 85281, United States
- Engineering
Research Center for Bio-mediated and Bio-inspired Geotechnics (CBBG), Arizona State University, 650 E Tyler Mall, Tempe, Arizona 85281, United States
| | - Presley Blake
- Biodesign
Swette Center for Environmental Biotechnology, Arizona State University, Tempe, Arizona 85287, United States
- School
of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, Arizona 85281, United States
- Engineering
Research Center for Bio-mediated and Bio-inspired Geotechnics (CBBG), Arizona State University, 650 E Tyler Mall, Tempe, Arizona 85281, United States
| | - Arantza Morán Reyes
- Biodesign
Swette Center for Environmental Biotechnology, Arizona State University, Tempe, Arizona 85287, United States
- Instituto
de Energías Renovables, Universidad
Nacional Autónoma de México, Xochicalco s/n, Azteca, Temixco, Morelos 62588, Mexico
| | - Riley N. Berg
- Biodesign
Swette Center for Environmental Biotechnology, Arizona State University, Tempe, Arizona 85287, United States
- School
of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, Arizona 85281, United States
- Engineering
Research Center for Bio-mediated and Bio-inspired Geotechnics (CBBG), Arizona State University, 650 E Tyler Mall, Tempe, Arizona 85281, United States
| | - Christopher Muse
- Biodesign
Swette Center for Environmental Biotechnology, Arizona State University, Tempe, Arizona 85287, United States
- School
of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, Arizona 85281, United States
- Engineering
Research Center for Bio-mediated and Bio-inspired Geotechnics (CBBG), Arizona State University, 650 E Tyler Mall, Tempe, Arizona 85281, United States
| | - Aide Robles
- Biodesign
Swette Center for Environmental Biotechnology, Arizona State University, Tempe, Arizona 85287, United States
- School
of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, Arizona 85281, United States
- Engineering
Research Center for Bio-mediated and Bio-inspired Geotechnics (CBBG), Arizona State University, 650 E Tyler Mall, Tempe, Arizona 85281, United States
- Haley
& Aldrich, Inc., 400 E Van Buren St., Suite 545, Phoenix, Arizona 85004, United States
| | - Nasser Hamdan
- School
of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, Arizona 85281, United States
- Engineering
Research Center for Bio-mediated and Bio-inspired Geotechnics (CBBG), Arizona State University, 650 E Tyler Mall, Tempe, Arizona 85281, United States
| | - Min-Ying Chu
- Haley
& Aldrich, Inc., 400 E Van Buren St., Suite 545, Phoenix, Arizona 85004, United States
| | - Anca G. Delgado
- Biodesign
Swette Center for Environmental Biotechnology, Arizona State University, Tempe, Arizona 85287, United States
- School
of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, Arizona 85281, United States
- Engineering
Research Center for Bio-mediated and Bio-inspired Geotechnics (CBBG), Arizona State University, 650 E Tyler Mall, Tempe, Arizona 85281, United States
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5
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Sakoula D, Schatteman A, Blom P, Jetten MSM, van Kessel MAHJ, Lehtovirta-Morley L, Lücker S. Activity-based labelling of ammonia- and alkane-oxidizing microorganisms including ammonia-oxidizing archaea. ISME COMMUNICATIONS 2024; 4:ycae092. [PMID: 39071849 PMCID: PMC11283641 DOI: 10.1093/ismeco/ycae092] [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: 06/19/2024] [Revised: 07/06/2024] [Accepted: 07/09/2024] [Indexed: 07/30/2024]
Abstract
Recently, an activity-based labelling protocol for the in vivo detection of ammonia- and alkane-oxidizing bacteria became available. This functional tagging technique enabled targeted studies of these environmentally widespread functional groups, but it failed to capture ammonia-oxidizing archaea (AOA). Since their first discovery, AOA have emerged as key players within the biogeochemical nitrogen cycle, but our knowledge regarding their distribution and abundance in natural and engineered ecosystems is mainly derived from PCR-based and metagenomic studies. Furthermore, the archaeal ammonia monooxygenase is distinctly different from its bacterial counterparts and remains poorly understood. Here, we report on the development of an activity-based labelling protocol for the fluorescent detection of all ammonia- and alkane-oxidizing prokaryotes, including AOA. In this protocol, 1,5-hexadiyne is used as inhibitor of ammonia and alkane oxidation and as bifunctional enzyme probe for the fluorescent labelling of cells via the Cu(I)-catalyzed alkyne-azide cycloaddition reaction. Besides efficient activity-based labelling of ammonia- and alkane-oxidizing microorganisms, this method can also be employed in combination with deconvolution microscopy for determining the subcellular localization of their ammonia- and alkane-oxidizing enzyme systems. Labelling of these enzymes in diverse ammonia- and alkane-oxidizing microorganisms allowed their visualization on the cytoplasmic membranes, the intracytoplasmic membrane stacks of ammonia- and methane-oxidizing bacteria, and, fascinatingly, on vesicle-like structures in one AOA species. The development of this novel activity-based labelling method for ammonia- and alkane-oxidizers will be a valuable addition to the expanding molecular toolbox available for research of nitrifying and alkane-oxidizing microorganisms.
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Affiliation(s)
- Dimitra Sakoula
- Department of Microbiology, RIBES, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, the Netherlands
| | - Arne Schatteman
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, Norfolk, NR4 7TJ, United Kingdom
| | - Pieter Blom
- Department of Microbiology, RIBES, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, the Netherlands
| | - Mike S M Jetten
- Department of Microbiology, RIBES, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, the Netherlands
| | - Maartje A H J van Kessel
- Department of Microbiology, RIBES, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, the Netherlands
| | - Laura Lehtovirta-Morley
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, Norfolk, NR4 7TJ, United Kingdom
| | - Sebastian Lücker
- Department of Microbiology, RIBES, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, the Netherlands
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6
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Wright CL, Lehtovirta-Morley LE. Nitrification and beyond: metabolic versatility of ammonia oxidising archaea. THE ISME JOURNAL 2023; 17:1358-1368. [PMID: 37452095 PMCID: PMC10432482 DOI: 10.1038/s41396-023-01467-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 06/09/2023] [Accepted: 06/21/2023] [Indexed: 07/18/2023]
Abstract
Ammonia oxidising archaea are among the most abundant living organisms on Earth and key microbial players in the global nitrogen cycle. They carry out oxidation of ammonia to nitrite, and their activity is relevant for both food security and climate change. Since their discovery nearly 20 years ago, major insights have been gained into their nitrogen and carbon metabolism, growth preferences and their mechanisms of adaptation to the environment, as well as their diversity, abundance and activity in the environment. Despite significant strides forward through the cultivation of novel organisms and omics-based approaches, there are still many knowledge gaps on their metabolism and the mechanisms which enable them to adapt to the environment. Ammonia oxidising microorganisms are typically considered metabolically streamlined and highly specialised. Here we review the physiology of ammonia oxidising archaea, with focus on aspects of metabolic versatility and regulation, and discuss these traits in the context of nitrifier ecology.
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Affiliation(s)
- Chloe L Wright
- School of Biological Sciences, University of East Anglia, Norwich, NR4 7TJ, United Kingdom
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7
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Choi E, Chaudhry SI, Martens-Habbena W. Role of Nitric Oxide in Hydroxylamine Oxidation by Ammonia-Oxidizing Bacteria. Appl Environ Microbiol 2023; 89:e0217322. [PMID: 37439697 PMCID: PMC10467338 DOI: 10.1128/aem.02173-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 06/27/2023] [Indexed: 07/14/2023] Open
Abstract
An important role of nitric oxide (NO) as either a free intermediate in the NH3 oxidation pathway or a potential oxidant for NH3 or NH2OH has been proposed for ammonia-oxidizing bacteria (AOB) and archaea (AOA), respectively. However, tracing NO metabolism at low concentrations remains notoriously difficult. Here, we use electrochemical sensors and the mild NO scavenger 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (PTIO) to trace apparent NO concentration and determine production rates at low micromolar concentrations in the model AOB strain Nitrosomonas europaea. In agreement with previous studies, we found that PTIO does not affect NH3 oxidation instantaneously in both Nitrosospira briensis and Nitrosomonas europaea, unlike inhibitors for ammonia oxidation such as allylthiourea and acetylene, although it effectively scavenged NO from the cell suspensions. Quantitative analysis showed that NO production by N. europaea amounted to 3.15% to 6.23% of NO2- production, whereas N. europaea grown under O2 limitation produced NO equivalent to up to 40% of NO2- production at high substrate concentrations. In addition, we found that PTIO addition to N. europaea grown under O2 limitation abolished N2O production. These results indicate different turnover rates of NO during NH3 oxidation under O2-replete and O2-limited growth conditions in AOB. The results suggest that NO may not be a free intermediate or remain tightly bound to iron centers of enzymes during hydroxylamine oxidation and that only NH3 saturation and adaptation to O2 limitation may lead to significant dissociation of NO from hydroxylamine dehydrogenase. IMPORTANCE Ammonia oxidation by chemolithoautotrophic ammonia-oxidizing bacteria (AOB) is thought to contribute significantly to global nitrous oxide (N2O) emissions and leaching of oxidized nitrogen, particularly through their activity in nitrogen (N)-fertilized agricultural production systems. Although substantial efforts have been made to characterize the N metabolism in AOB, recent findings suggest that nitric oxide (NO) may play an important mechanistic role as a free intermediate of hydroxylamine oxidation in AOB, further implying that besides hydroxylamine dehydrogenase (HAO), additional enzymes may be required to complete the ammonia oxidation pathway. However, the NO spin trap PTIO was found to not inhibit ammonia oxidation in AOB. This study provides a combination of physiological and spectroscopic evidence that PTIO indeed scavenges only free NO in AOB and that significant amounts of free NO are produced only during incomplete hydroxylamine oxidation or nitrifier denitrification under O2-limited growth conditions.
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Affiliation(s)
- Eunkyung Choi
- Fort Lauderdale Research and Education Center, Microbiology & Cell Science Department, University of Florida, Davie, Florida, USA
| | - Sana I. Chaudhry
- Fort Lauderdale Research and Education Center, Microbiology & Cell Science Department, University of Florida, Davie, Florida, USA
| | - Willm Martens-Habbena
- Fort Lauderdale Research and Education Center, Microbiology & Cell Science Department, University of Florida, Davie, Florida, USA
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8
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Krammer L, Breinbauer R. Activity‐Based Protein Profiling of Oxidases and Reductases. Isr J Chem 2023. [DOI: 10.1002/ijch.202200086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Leo Krammer
- Institute of Organic Chemistry Graz University of Technology Stremayrgasse 9 A-8010 Graz Austria
| | - Rolf Breinbauer
- Institute of Organic Chemistry Graz University of Technology Stremayrgasse 9 A-8010 Graz Austria
- BIOTECHMED Graz A-8010 Graz Austria
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9
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Oyarzun Mejia AP, Hyman MR. Diyne inactivators and activity-based fluorescent labeling of phenol hydroxylase in Pseudomonas sp. CF600. FEMS Microbiol Lett 2023; 370:6973202. [PMID: 36617235 DOI: 10.1093/femsle/fnad002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Revised: 09/09/2022] [Accepted: 01/05/2023] [Indexed: 01/09/2023] Open
Abstract
An activity-based labeling (ABL) approach was investigated for the phenol-oxidizing bacterium, Pseudomonas sp. CF600. Phenol-grown cells were exposed to several different terminal diynes, and following cell breakage, extracts of these cells were added to copper-catalyzed alkyne/azide cycloaddition reactions containing Alexa Fluor 647 azide. Analysis of total cell proteins by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and near-infrared scanning demonstrated covalent fluorescent labeling of a 58- and a 34-kDa polypeptide in all diyne-treated cell types. Further studies using 1,4-diethynylbenzene (DEB) demonstrated that these labeled polypeptides were consistently detected in cells grown on substrates that exhibited phenol-dependent O2 uptake activity but not observed when cells were grown on substrates such as dextrose or catechol that did not support this activity. Fluorescent labeling of the two polypeptides in DEB-treated, phenol-grown cells was time dependent and was inhibited by several known substrates for phenol hydroxylase. These results suggest that diverse diynes act as mechanism-based inactivators of phenol hydroxylase in Pseudomonas sp. CF600 and that this effect can be exploited by ABL approaches to selectively label the major 58- and 34-kDa subunits of the hydroxylase component of this complex enzyme.
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Affiliation(s)
| | - Michael R Hyman
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695, USA
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10
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Oshiki M, Gao L, Zhang L, Okabe S. NH 2OH Disproportionation Mediated by Anaerobic Ammonium-oxidizing (Anammox) Bacteria. Microbes Environ 2022; 37. [PMID: 35418545 PMCID: PMC9530737 DOI: 10.1264/jsme2.me21092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Anammox bacteria produce N2 gas by oxidizing NH4+ with NO2–, and hydroxylamine (NH2OH) is a potential intermediate of the anammox process. N2 gas production occurs when anammox bacteria are incubated with NH2OH only, indicating their capacity for NH2OH disproportionation with NH2OH serving as both the electron donor and acceptor. Limited information is currently available on NH2OH disproportionation by anammox bacteria; therefore, the stoichiometry of anammox bacterial NH2OH disproportionation was examined in the present study using 15N-tracing techniques. The anammox bacteria, Brocadia sinica, Jettenia caeni, and Scalindua sp. were incubated with the addition of 15NH2OH, and the production of 15N-labeled nitrogenous compounds was assessed. The anammox bacteria tested performed NH2OH disproportionation and produced 15-15N2 gas and NH4+ as reaction products. The addition of acetylene, an inhibitor of the anammox process, reduced the activity of NH2OH disproportionation, but not completely. The growth of B. sinica by NH2OH disproportionation (–240.3 kJ mol NH2OH–1 under standard conditions) was also tested in 3 up-flow column anammox reactors fed with 1) 0.7 mM NH2OH only, 2) 0.7 mM NH2OH and 0.5 mM NH4+, and 3) 0.7 mM NH2OH and 0.5 mM NO2–. NH2OH consumption activities were markedly reduced after 7 d of operation, indicating that B. sinica was unable to maintain its activity or biomass by NH2OH disproportionation.
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Affiliation(s)
- Mamoru Oshiki
- Division of Environmental Engineering, Faculty of Engineering, Hokkaido University
| | - Lin Gao
- Division of Environmental Engineering, Faculty of Engineering, Hokkaido University
| | - Lei Zhang
- Division of Environmental Engineering, Faculty of Engineering, Hokkaido University
| | - Satoshi Okabe
- Division of Environmental Engineering, Faculty of Engineering, Hokkaido University
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11
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Li S, Peng L, Yang C, Song S, Xu Y. Cometabolic biodegradation of antibiotics by ammonia oxidizing microorganisms during wastewater treatment processes. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2022; 305:114336. [PMID: 34953231 DOI: 10.1016/j.jenvman.2021.114336] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 11/27/2021] [Accepted: 12/16/2021] [Indexed: 05/04/2023]
Abstract
Studies on antibiotic removal during wastewater treatment processes are crucial since their release into the environment could bring potential threats to human health and ecosystem. Cometabolic biodegradation of antibiotics by ammonia oxidizing microorganisms (AOMs) has received special attentions due to the enhanced removal of antibiotics during nitrification processes. However, the interactions between antibiotics and AOMs are less well-elucidated. In this review, the recent research proceedings on cometabolic biodegradation of antibiotics by AOMs were summarized. Ammonia oxidizing bacteria (AOB), ammonia oxidizing archaea (AOA) and complete ammonia oxidizers (comammox) played significant roles in both nitrification and cometabolic biodegradation of antibiotics. Antibiotics at varying concentrations might pose inhibiting or stimulating effect on AOMs, influencing the microbial activity, community abundance and ammonia monooxygenase subunit A gene expression level. AOMs-induced cometabolic biodegradation products were analyzed as well as the corresponding pathways for each type of antibiotics. The effects of ammonium availability, initial antibiotic concentration, sludge retention time and temperature were assessed on the cometabolic biodegradation efficiencies of antibiotics. This work might provide further insights into the fate and removal of antibiotics during nitrification processes.
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Affiliation(s)
- Shengjun Li
- Hubei Key Laboratory of Mineral Resources Processing and Environment, Wuhan University of Technology, Luoshi Road 122, Wuhan, Hubei, 430070, China; School of Resources and Environmental Engineering, Wuhan University of Technology, Luoshi Road 122, Wuhan, Hubei, 430070, China
| | - Lai Peng
- Hubei Key Laboratory of Mineral Resources Processing and Environment, Wuhan University of Technology, Luoshi Road 122, Wuhan, Hubei, 430070, China; School of Resources and Environmental Engineering, Wuhan University of Technology, Luoshi Road 122, Wuhan, Hubei, 430070, China.
| | - Chenguang Yang
- Institute of Deep Sea Science and Engineering, Chinese Academy of Sciences, Sanya Hainan, 572000, China
| | - Shaoxian Song
- Hubei Key Laboratory of Mineral Resources Processing and Environment, Wuhan University of Technology, Luoshi Road 122, Wuhan, Hubei, 430070, China; School of Resources and Environmental Engineering, Wuhan University of Technology, Luoshi Road 122, Wuhan, Hubei, 430070, China
| | - Yifeng Xu
- Hubei Key Laboratory of Mineral Resources Processing and Environment, Wuhan University of Technology, Luoshi Road 122, Wuhan, Hubei, 430070, China; School of Resources and Environmental Engineering, Wuhan University of Technology, Luoshi Road 122, Wuhan, Hubei, 430070, China.
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12
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Su Q, Schittich AR, Jensen MM, Ng H, Smets BF. Role of Ammonia Oxidation in Organic Micropollutant Transformation during Wastewater Treatment: Insights from Molecular, Cellular, and Community Level Observations. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:2173-2188. [PMID: 33543927 DOI: 10.1021/acs.est.0c06466] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Organic micropollutants (OMPs) are a threat to aquatic environments, and wastewater treatment plants may act as a source or a barrier of OMPs entering the environment. Understanding the fate of OMPs in wastewater treatment processes is needed to establish efficient OMP removal strategies. Enhanced OMP biotransformation has been documented during biological nitrogen removal and has been attributed to the cometabolic activity of ammonia-oxidizing bacteria (AOB) and, specifically, to the ammonia monooxygenase (AMO) enzyme. Yet, the exact mechanisms of OMP biotransformation are often unknown. This critical review aims to fundamentally and quantitatively evaluate the role of ammonia oxidation in OMP biotransformation during wastewater treatment processes. OMPs can be transformed by AOB via direct and indirect enzymatic reactions: AMO directly transforms OMPs primarily via hydroxylation, while biologically produced reactive nitrogen species (hydroxylamine (NH2OH), nitrite (NO2-), and nitric oxide (NO)) can chemically transform OMPs through nitration, hydroxylation, and deamination and can contribute significantly to the observed OMP transformations. OMPs containing alkyl, aliphatic hydroxyl, ether, and sulfide functional groups as well as substituted aromatic rings and aromatic primary amines can be biotransformed by AMO, while OMPs containing alkyl groups, phenols, secondary amines, and aromatic primary amines can undergo abiotic transformations mediated by reactive nitrogen species. Higher OMP biotransformation efficiencies and rates are obtained in AOB-dominant microbial communities, especially in autotrophic reactors performing nitrification or nitritation, than in non-AOB-dominant microbial communities. The biotransformations of OMPs in wastewater treatment systems can often be linked to ammonium (NH4+) removal following two central lines of evidence: (i) Similar transformation products (i.e., hydroxylated, nitrated, and desaminated TPs) are detected in wastewater treatment systems as in AOB pure cultures. (ii) Consistency in OMP biotransformation (rbio, μmol/g VSS/d) to NH4+ removal (rNH4+, mol/g VSS/d) rate ratios (rbio/rNH4+) is observed for individual OMPs across different systems with similar rNH4+ and AOB abundances. In this review, we conclude that AOB are the main drivers of OMP biotransformation during wastewater treatment processes. The importance of biologically driven abiotic OMP transformation is quantitatively assessed, and functional groups susceptible to transformations by AMO and reactive nitrogen species are systematically classified. This critical review will improve the prediction of OMP transformation and facilitate the design of efficient OMP removal strategies during wastewater treatment.
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Affiliation(s)
- Qingxian Su
- National University of Singapore Environmental Research Institute, 5A Engineering Drive 1, 117411 Singapore, Singapore
- Department of Environmental Engineering, Technical University of Denmark, 2800 Kgs., Lyngby, Denmark
| | - Anna-Ricarda Schittich
- Department of Environmental Engineering, Technical University of Denmark, 2800 Kgs., Lyngby, Denmark
| | - Marlene Mark Jensen
- Department of Environmental Engineering, Technical University of Denmark, 2800 Kgs., Lyngby, Denmark
| | - Howyong Ng
- National University of Singapore Environmental Research Institute, 5A Engineering Drive 1, 117411 Singapore, Singapore
- Centre for Water Research, Department of Civil & Environmental Engineering, National University of Singapore, 1 Engineering Drive 2, 117576 Singapore, Singapore
| | - Barth F Smets
- Department of Environmental Engineering, Technical University of Denmark, 2800 Kgs., Lyngby, Denmark
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13
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Fuerst R, Breinbauer R. Activity-Based Protein Profiling (ABPP) of Oxidoreductases. Chembiochem 2021; 22:630-638. [PMID: 32881211 PMCID: PMC7894341 DOI: 10.1002/cbic.202000542] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 09/02/2020] [Indexed: 12/20/2022]
Abstract
Over the last two decades, activity-based protein profiling (ABPP) has been established as a tremendously useful proteomic tool for measuring the activity of proteins in their cellular context, annotating the function of uncharacterized proteins, and investigating the target profile of small-molecule inhibitors. Unlike hydrolases and other enzyme classes, which exhibit a characteristic nucleophilic residue, oxidoreductases have received much less attention in ABPP. In this minireview, the state of the art of ABPP of oxidoreductases is described and the scope and limitations of the existing approaches are discussed. It is noted that several ABPP probes have been described for various oxidases, but none so far for a reductase, which gives rise to opportunities for future research.
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Affiliation(s)
- Rita Fuerst
- Institute of Organic ChemistryGraz University of TechnologyStremayrgasse 98010GrazAustria
| | - Rolf Breinbauer
- Institute of Organic ChemistryGraz University of TechnologyStremayrgasse 98010GrazAustria
- BIOTECHMEDGrazAustria
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14
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Corrochano-Monsalve M, González-Murua C, Bozal-Leorri A, Lezama L, Artetxe B. Mechanism of action of nitrification inhibitors based on dimethylpyrazole: A matter of chelation. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 752:141885. [PMID: 32890835 DOI: 10.1016/j.scitotenv.2020.141885] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 08/19/2020] [Accepted: 08/20/2020] [Indexed: 05/25/2023]
Abstract
In agriculture, the applied nitrogen (N) can be lost in the environment in different forms because of microbial transformations. It is of special concern the nitrate (NO3-) leaching and the nitrous oxide (N2O) emissions, due to their negative environmental impacts. Nitrification inhibitors (NIs) based on dimethylpyrazole (DMP) are applied worldwide in order to reduce N losses. These compounds delay ammonium (NH4+) oxidation by inhibiting ammonia-oxidizing bacteria (AOB) growth. However, their mechanism of action has not been demonstrated, which represent an important lack of knowledge to use them correctly. In this work, through chemical and biological analysis, we unveil the mechanism of action of the commonly applied 3,4-dimethyl-1H-pyrazole dihydrogen phosphate (DMPP) and the new DMP-based NI, 2-(3,4-dimethyl-1H-pyrazol-1-yl)-succinic acid (DMPSA). Our results show that DMP and DMPSA form complexes with copper (Cu2+) cations, an indispensable cofactor in the nitrification pathway. Three coordination compounds namely [Cu(DMP)4Cl2] (CuDMP1), [Cu(DMP)4SO4]n (CuDMP2) and [Cu(DMPSA)2]·H2O (CuDMPSA) have been synthesized and chemical and structurally characterized. The CuDMPSA complex is more stable than those containing DMP ligands; however, both NIs show the same nitrification inhibition efficiency in soils with different Cu contents, suggesting that the active specie in both cases is DMP. Our soil experiment reveals that the usual application dose is enough to inhibit nitrification within the range of Cu and Zn contents present in agricultural soils, although their effects vary depending on the content of these elements. As a result of AOB inhibition by these NIs, N2O-reducing bacteria seem to be beneficed in Cu-limited soils due to a reduction in the competence. This opens up the possibility to induce N2O reduction to N2 through Cu fertilization. On the other hand, when fertilizing with micronutrients such as Cu and Zn, the use of NIs could be beneficial to counteract the increase of nitrification derived from their application.
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Affiliation(s)
- Mario Corrochano-Monsalve
- Department of Plant Biology and Ecology, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), Leioa, Spain.
| | - Carmen González-Murua
- Department of Plant Biology and Ecology, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), Leioa, Spain
| | - Adrián Bozal-Leorri
- Department of Plant Biology and Ecology, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), Leioa, Spain
| | - Luis Lezama
- Department of Inorganic Chemistry, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), Leioa, Spain
| | - Beñat Artetxe
- Department of Inorganic Chemistry, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), Leioa, Spain
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15
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Wright CL, Schatteman A, Crombie AT, Murrell JC, Lehtovirta-Morley LE. Inhibition of Ammonia Monooxygenase from Ammonia-Oxidizing Archaea by Linear and Aromatic Alkynes. Appl Environ Microbiol 2020; 86:e02388-19. [PMID: 32086308 PMCID: PMC7170481 DOI: 10.1128/aem.02388-19] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 02/15/2020] [Indexed: 01/20/2023] Open
Abstract
Ammonia monooxygenase (AMO) is a key nitrogen-transforming enzyme belonging to the same copper-dependent membrane monooxygenase family (CuMMO) as the particulate methane monooxygenase (pMMO). The AMO from ammonia-oxidizing archaea (AOA) is very divergent from both the AMO of ammonia-oxidizing bacteria (AOB) and the pMMO from methanotrophs, and little is known about the structure or substrate range of the archaeal AMO. This study compares inhibition by C2 to C8 linear 1-alkynes of AMO from two phylogenetically distinct strains of AOA, "Candidatus Nitrosocosmicus franklandus" C13 and "Candidatus Nitrosotalea sinensis" Nd2, with AMO from Nitrosomonas europaea and pMMO from Methylococcus capsulatus (Bath). An increased sensitivity of the archaeal AMO to short-chain-length alkynes (≤C5) appeared to be conserved across AOA lineages. Similarities in C2 to C8 alkyne inhibition profiles between AMO from AOA and pMMO from M. capsulatus suggested that the archaeal AMO has a narrower substrate range than N. europaea AMO. Inhibition of AMO from "Ca Nitrosocosmicus franklandus" and N. europaea by the aromatic alkyne phenylacetylene was also investigated. Kinetic data revealed that the mechanisms by which phenylacetylene inhibits "Ca Nitrosocosmicus franklandus" and N. europaea are different, indicating differences in the AMO active site between AOA and AOB. Phenylacetylene was found to be a specific and irreversible inhibitor of AMO from "Ca Nitrosocosmicus franklandus," and it does not compete with NH3 for binding at the active site.IMPORTANCE Archaeal and bacterial ammonia oxidizers (AOA and AOB, respectively) initiate nitrification by oxidizing ammonia to hydroxylamine, a reaction catalyzed by ammonia monooxygenase (AMO). AMO enzyme is difficult to purify in its active form, and its structure and biochemistry remain largely unexplored. The bacterial AMO and the closely related particulate methane monooxygenase (pMMO) have a broad range of hydrocarbon cooxidation substrates. This study provides insights into the AMO of previously unstudied archaeal genera, by comparing the response of the archaeal AMO, a bacterial AMO, and pMMO to inhibition by linear 1-alkynes and the aromatic alkyne, phenylacetylene. Reduced sensitivity to inhibition by larger alkynes suggests that the archaeal AMO has a narrower hydrocarbon substrate range than the bacterial AMO, as previously reported for other genera of AOA. Phenylacetylene inhibited the archaeal and bacterial AMOs at different thresholds and by different mechanisms of inhibition, highlighting structural differences between the two forms of monooxygenase.
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Affiliation(s)
- Chloë L Wright
- School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
| | - Arne Schatteman
- School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
| | - Andrew T Crombie
- School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
| | - J Colin Murrell
- School of Environmental Sciences, University of East Anglia, Norwich, United Kingdom
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16
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Wendeborn S. Chemie, Biologie und Regulierung der Nitrifikation von Ammonium im Boden. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.201903014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Sebastian Wendeborn
- Fachhochschule Nordwestschweiz FHNWHochschule für Life SciencesInstitut für Chemie und Bioanalytik Hofackerstrasse 30 CH-4132 Muttenz Schweiz
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17
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Wendeborn S. The Chemistry, Biology, and Modulation of Ammonium Nitrification in Soil. Angew Chem Int Ed Engl 2019; 59:2182-2202. [PMID: 31116902 DOI: 10.1002/anie.201903014] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 05/15/2019] [Indexed: 11/11/2022]
Abstract
Approximately two percent of the world's energy is consumed in the production of ammonia from hydrogen and nitrogen gas. Ammonia is used as a fertilizer ingredient for agriculture and distributed in the environment on an enormous scale to promote crop growth in intensive farming. Only 30-50 % of the nitrogen applied is assimilated by crop plants; the remaining 50-70 % goes into biological processes such as nitrification by microbial metabolism in the soil. This leads to an imbalance in the global nitrogen cycle and higher nitrous oxide emissions (a potent and significant greenhouse gas) as well as contamination of ground and surface waters by nitrate from the nitrogen-fertilized farmland. This Review gives a critical overview of the current knowledge of soil microbes involved in the chemistry of ammonia nitrification, the structures and mechanisms of the enzymes involved, and phytochemicals capable of inhibiting ammonia nitrification.
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Affiliation(s)
- Sebastian Wendeborn
- University of Applied Sciences and Arts Northwestern Switzerland, School of Life Sciences, Institute for Chemistry and Bioanalytics, Hofackerstrasse 30, CH-4132, Muttenz, Switzerland
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18
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Semrau JD, DiSpirito AA. Methanobactin: A Novel Copper-Binding Compound Produced by Methanotrophs. ACTA ACUST UNITED AC 2019. [DOI: 10.1007/978-3-030-23261-0_7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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19
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Nsenga Kumwimba M, Meng F. Roles of ammonia-oxidizing bacteria in improving metabolism and cometabolism of trace organic chemicals in biological wastewater treatment processes: A review. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 659:419-441. [PMID: 31096373 DOI: 10.1016/j.scitotenv.2018.12.236] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2018] [Revised: 11/20/2018] [Accepted: 12/15/2018] [Indexed: 05/27/2023]
Abstract
While there has been a significant recent improvement in the removal of pollutants in natural and engineered systems, trace organic chemicals (TrOCs) are posing a major threat to aquatic environments and human health. There is a critical need for developing potential strategies that aim at enhancing metabolism and/or cometabolism of these compounds. Recently, knowledge regarding biodegradation of TrOCs by ammonia-oxidizing bacteria (AOB) has been widely developed. This review aims to delineate an up-to-date version of the ecophysiology of AOB and outline current knowledge related to biodegradation efficiencies of the frequently reported TrOCs by AOB. The paper also provides an insight into biodegradation pathways by AOB and transformation products of these compounds and makes recommendations for future research of AOB. In brief, nitrifying WWTFs (wastewater treatment facilities) were superior in degrading most TrOCs than non-nitrifying WWTFs due to cometabolic biodegradation by the AOB. To fully understand and/or enhance the cometabolic biodegradation of TrOCs by AOB, recent molecular research has focused on numerous crucial factors including availability of the compounds to AOB, presence of growth substrate (NH4-N), redox potentials, microorganism diversity (AOB and heterotrophs), physicochemical properties and operational parameters of the WWTFs, molecular structure of target TrOCs and membrane-based technologies, may all significantly impact the cometabolic biodegradation of TrOCs. Still, further exploration is required to elucidate the mechanisms involved in biodegradation of TrOCs by AOB and the toxicity levels of formed products.
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Affiliation(s)
- Mathieu Nsenga Kumwimba
- School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, PR China; Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou 510275, PR China; Faculty of Agronomy, Department of Natural Resources and Environmental Management, University of Lubumbashi, Democratic Republic of the Congo
| | - Fangang Meng
- School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, PR China; Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou 510275, PR China.
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20
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Beeckman F, Motte H, Beeckman T. Nitrification in agricultural soils: impact, actors and mitigation. Curr Opin Biotechnol 2018; 50:166-173. [PMID: 29414056 DOI: 10.1016/j.copbio.2018.01.014] [Citation(s) in RCA: 119] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Accepted: 01/11/2018] [Indexed: 12/22/2022]
Abstract
Nitrogen is one of the most important nutrients for plant growth and hence heavily applied in agricultural systems via fertilization. Nitrification, that is, the conversion of ammonium via nitrite to nitrate by soil microorganisms, however, leads to nitrate leaching and gaseous nitrous oxide production and as such to an up to 50% loss of nitrogen availability for the plant. Nitrate leaching also results in eutrophication of groundwater, drinking water and recreational waters, toxic algal blooms and biodiversity loss, while nitrous oxide is a greenhouse gas with a global warming potential 300× greater than carbon dioxide. Logically, inhibition of nitrification is an important strategy used in agriculture to reduce nitrogen losses, and contributes to a more environmental-friendly practice. However, recently identified and crucial players in nitrification, that is, ammonia-oxidizing archaea and comammox bacteria, seem to be under-investigated in this respect. In this review, we give an update on the different pathways in ammonia oxidation, the relevance for agriculture and the interaction with nitrification inhibitors. As such, we hope to pinpoint possible strategies to optimize the efficiency of nitrification inhibition.
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Affiliation(s)
- Fabian Beeckman
- Ghent University, Department of Plant Biotechnology and Bioinformatics, Technologiepark 927, 9052 Ghent, Belgium; VIB Center for Plant Systems Biology, Technologiepark 927, 9052 Ghent, Belgium
| | - Hans Motte
- Ghent University, Department of Plant Biotechnology and Bioinformatics, Technologiepark 927, 9052 Ghent, Belgium; VIB Center for Plant Systems Biology, Technologiepark 927, 9052 Ghent, Belgium.
| | - Tom Beeckman
- Ghent University, Department of Plant Biotechnology and Bioinformatics, Technologiepark 927, 9052 Ghent, Belgium; VIB Center for Plant Systems Biology, Technologiepark 927, 9052 Ghent, Belgium
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21
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Ross MO, Rosenzweig AC. A tale of two methane monooxygenases. J Biol Inorg Chem 2017; 22:307-319. [PMID: 27878395 PMCID: PMC5352483 DOI: 10.1007/s00775-016-1419-y] [Citation(s) in RCA: 148] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Accepted: 11/15/2016] [Indexed: 11/24/2022]
Abstract
Methane monooxygenase (MMO) enzymes activate O2 for oxidation of methane. Two distinct MMOs exist in nature, a soluble form that uses a diiron active site (sMMO) and a membrane-bound form with a catalytic copper center (pMMO). Understanding the reaction mechanisms of these enzymes is of fundamental importance to biologists and chemists, and is also relevant to the development of new biocatalysts. The sMMO catalytic cycle has been elucidated in detail, including O2 activation intermediates and the nature of the methane-oxidizing species. By contrast, many aspects of pMMO catalysis remain unclear, most notably the nuclearity and molecular details of the copper active site. Here, we review the current state of knowledge for both enzymes, and consider pMMO O2 activation intermediates suggested by computational and synthetic studies in the context of existing biochemical data. Further work is needed on all fronts, with the ultimate goal of understanding how these two remarkable enzymes catalyze a reaction not readily achieved by any other metalloenzyme or biomimetic compound.
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Affiliation(s)
- Matthew O Ross
- Departments of Molecular Biosciences and of Chemistry, Northwestern University, Evanston, IL, 60208, USA
| | - Amy C Rosenzweig
- Departments of Molecular Biosciences and of Chemistry, Northwestern University, Evanston, IL, 60208, USA.
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22
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Bennett K, Sadler NC, Wright AT, Yeager C, Hyman MR. Activity-Based Protein Profiling of Ammonia Monooxygenase in Nitrosomonas europaea. Appl Environ Microbiol 2016; 82:2270-2279. [PMID: 26826234 PMCID: PMC4959501 DOI: 10.1128/aem.03556-15] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2015] [Accepted: 01/27/2016] [Indexed: 11/20/2022] Open
Abstract
Nitrosomonas europaea is an aerobic nitrifying bacterium that oxidizes ammonia (NH3) to nitrite (NO2 (-)) through the sequential activities of ammonia monooxygenase (AMO) and hydroxylamine dehydrogenase (HAO). Many alkynes are mechanism-based inactivators of AMO, and here we describe an activity-based protein profiling method for this enzyme using 1,7-octadiyne (17OD) as a probe. Inactivation of NH4 (+)-dependent O2 uptake by N. europaea by 17OD was time- and concentration-dependent. The effects of 17OD were specific for ammonia-oxidizing activity, andde novoprotein synthesis was required to reestablish this activity after cells were exposed to 17OD. Cells were reacted with Alexa Fluor 647 azide using a copper-catalyzed azide-alkyne cycloaddition (CuAAC) (click) reaction, solubilized, and analyzed by SDS-PAGE and infrared (IR) scanning. A fluorescent 28-kDa polypeptide was observed for cells previously exposed to 17OD but not for cells treated with either allylthiourea or acetylene prior to exposure to 17OD or for cells not previously exposed to 17OD. The fluorescent polypeptide was membrane associated and aggregated when heated with β-mercaptoethanol and SDS. The fluorescent polypeptide was also detected in cells pretreated with other diynes, but not in cells pretreated with structural homologs containing a single ethynyl functional group. The membrane fraction from 17OD-treated cells was conjugated with biotin-azide and solubilized in SDS. Streptavidin affinity-purified polypeptides were on-bead trypsin-digested, and amino acid sequences of the peptide fragments were determined by liquid chromatography-mass spectrometry (LC-MS) analysis. Peptide fragments from AmoA were the predominant peptides detected in 17OD-treated samples. In-gel digestion and matrix-assisted laser desorption ionization-tandem time of flight (MALDI-TOF/TOF) analyses also confirmed that the fluorescent 28-kDa polypeptide was AmoA.
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Affiliation(s)
- Kristen Bennett
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina, USA
| | - Natalie C Sadler
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Aaron T Wright
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Chris Yeager
- Biosciences Division, Los Alamos National Laboratory, Los Alamos, New Mexico, USA
| | - Michael R Hyman
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina, USA
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Acetylene hydratase: a non-redox enzyme with tungsten and iron-sulfur centers at the active site. J Biol Inorg Chem 2016; 21:29-38. [PMID: 26790879 DOI: 10.1007/s00775-015-1330-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 12/30/2015] [Indexed: 01/05/2023]
Abstract
In living systems, tungsten is exclusively found in microbial enzymes coordinated by the pyranopterin cofactor, with additional metal coordination provided by oxygen and/or sulfur, and/or selenium atoms in diverse arrangements. Prominent examples are formate dehydrogenase, formylmethanofuran dehydrogenase, and aldehyde oxidoreductase all of which catalyze redox reactions. The bacterial enzyme acetylene hydratase (AH) stands out of its class as it catalyzes the conversion of acetylene to acetaldehyde, clearly a non-redox reaction and a reaction distinct from the reduction of acetylene to ethylene by nitrogenase. AH harbors two pyranopterins bound to W, and a [4Fe-4S] cluster. W is coordinated by four dithiolene sulfur atoms, one cysteine sulfur, and one oxygen ligand. AH activity requires a strong reductant suggesting W(IV) as the active oxidation state. Two different types of reaction pathways have been proposed. The 1.26 Å structure reveals a water molecule coordinated to W which could gain a partially positive net charge by the adjacent protonated Asp-13, enabling a direct attack of C2H2. To access the W-Asp site, a substrate channel was evolved distant from where it is found in other members of the DMSOR family. Computational studies of this second shell mechanism led to unrealistically high energy barriers, and alternative pathways were proposed where C2H2 binds directly to W. The architecture of the catalytic cavity, the specificity for C2H2 and the results from site-directed mutagenesis do not support this first shell mechanism. More investigations including structural information on the binding of C2H2 are needed to present a conclusive answer.
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24
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Pham MD, Lin YP, Van Vuong Q, Nagababu P, Chang BTA, Ng KY, Chen CH, Han CC, Chen CH, Li MS, Yu SSF, Chan SI. Inactivation of the particulate methane monooxygenase (pMMO) in Methylococcus capsulatus (Bath) by acetylene. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2015; 1854:1842-1852. [DOI: 10.1016/j.bbapap.2015.08.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Revised: 07/29/2015] [Accepted: 08/09/2015] [Indexed: 11/25/2022]
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Hatzinger PB, Streger SH, Begley JF. Enhancing aerobic biodegradation of 1,2-dibromoethane in groundwater using ethane or propane and inorganic nutrients. JOURNAL OF CONTAMINANT HYDROLOGY 2015; 172:61-70. [PMID: 25437228 DOI: 10.1016/j.jconhyd.2014.11.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Revised: 10/27/2014] [Accepted: 11/14/2014] [Indexed: 06/04/2023]
Abstract
1,2-Dibromoethane (ethylene dibromide; EDB) is a probable human carcinogen that was previously used as both a soil fumigant and a scavenger in leaded gasoline. EDB has been observed to persist in soils and groundwater, particularly under oxic conditions. The objective of this study was to evaluate options to enhance the aerobic degradation of EDB in groundwater, with a particular focus on possible in situ remediation strategies. Propane gas and ethane gas were observed to significantly stimulate the biodegradation of EDB in microcosms constructed with aquifer solids and groundwater from the FS-12 EDB plume at Joint Base Cape Cod (Cape Cod, MA), but only after inorganic nutrients were added. Ethene gas was also effective, but rates were appreciably slower than for ethane and propane. EDB was reduced to <0.02 μg/L, the Massachusetts state Maximum Contaminant Level (MCL), in microcosms that received ethane gas and inorganic nutrients. An enrichment culture (BE-3R) that grew on ethane or propane gas but not EDB was obtained from the site materials. The degradation of EDB by this culture was inhibited by acetylene gas, suggesting that degradation is catalyzed by a monooxygenase enzyme. The BE-3R culture was also observed to biodegrade 1,2-dichloroethane (DCA), a compound commonly used in conjunction with EDB as a lead scavenger in gasoline. The data suggest that addition of ethane or propane gas with inorganic nutrients may be a viable option to enhance degradation of EDB in groundwater aquifers to below current state or federal MCL values.
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Affiliation(s)
- Paul B Hatzinger
- Biotechnology Development and Applications Group, CB&I Federal Services, Lawrenceville, NJ 08648, United States.
| | - Sheryl H Streger
- Biotechnology Development and Applications Group, CB&I Federal Services, Lawrenceville, NJ 08648, United States
| | - James F Begley
- MT Environmental Restoration, Plymouth, MA 02360, United States
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Sazinsky MH, Lippard SJ. Methane Monooxygenase: Functionalizing Methane at Iron and Copper. Met Ions Life Sci 2015; 15:205-56. [DOI: 10.1007/978-3-319-12415-5_6] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Liew EF, Tong D, Coleman NV, Holmes AJ. Mutagenesis of the hydrocarbon monooxygenase indicates a metal centre in subunit-C, and not subunit-B, is essential for copper-containing membrane monooxygenase activity. MICROBIOLOGY-SGM 2014; 160:1267-1277. [PMID: 24682027 DOI: 10.1099/mic.0.078584-0] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The hydrocarbon monooxygenase (HMO) of Mycobacterium NBB4 is a member of the copper-containing membrane monooxygenase (CuMMO) superfamily, which also contains particulate methane monooxygenases (pMMOs) and ammonia monooxygenases (AMOs). CuMMOs have broad applications due to their ability to catalyse the oxidation of difficult substrates of environmental and industrial relevance. Most of our understanding of CuMMO biochemistry is based on pMMOs and AMOs as models. All three available structures are from pMMOs. These share two metal sites: a dicopper centre coordinated by histidine residues in subunit-B and a 'variable-metal' site coordinated by carboxylate and histidine residues from subunit-C. The exact nature and role of these sites is strongly debated. Significant barriers to progress have been the physiologically specialized nature of methanotrophs and autotrophic ammonia-oxidizers, lack of a recombinant expression system for either enzyme and difficulty in purification of active protein. In this study we use the newly developed HMO model system to perform site-directed mutagenesis on the predicted metal-binding residues in the HmoB and HmoC of NBB4 HMO. All mutations of predicted HmoC metal centre ligands abolished enzyme activity. Mutation of a predicted copper-binding residue of HmoB (B-H155V) reduced activity by 81 %. Mutation of a site that shows conservation within physiologically defined subgroups of CuMMOs was shown to reduce relative HMO activity towards larger alkanes. The study demonstrates that the modelled dicopper site of subunit-B is not sufficient for HMO activity and that a metal centre predicted to be coordinated by residues in subunit-C is essential for activity.
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Affiliation(s)
- Elissa F Liew
- School of Molecular Bioscience, Building G08, University of Sydney, NSW 2006, Australia
| | - Daochen Tong
- School of Molecular Bioscience, Building G08, University of Sydney, NSW 2006, Australia
| | - Nicholas V Coleman
- School of Molecular Bioscience, Building G08, University of Sydney, NSW 2006, Australia
| | - Andrew J Holmes
- School of Molecular Bioscience, Building G08, University of Sydney, NSW 2006, Australia
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28
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Abstract
The investigation of unique chemical phenotypes has led to the discovery of enzymes with interesting behaviors that allow us to explore unusual function. The organofluorine-producing microbe Streptomyces cattleya has evolved a fluoroacetyl-CoA thioesterase (FlK) that demonstrates a surprisingly high level of discrimination for a single fluorine substituent on its substrate compared with the cellularly abundant hydrogen analog, acetyl-CoA. In this report, we show that the high selectivity of FlK is achieved through catalysis rather than molecular recognition, where deprotonation at the C(α) position to form a putative ketene intermediate only occurs on the fluorinated substrate, thereby accelerating the rate of hydrolysis 10(4)-fold compared with the nonfluorinated congener. These studies provide insight into mechanisms of catalytic selectivity in a native system where the existence of two reaction pathways determines substrate rather than product selection.
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Affiliation(s)
| | - Michelle C. Y. Chang
- Departments of Chemistry and
- Molecular and Cell Biology, University of California, Berkeley, CA 94720; and
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
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29
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Abstract
Particulate methane monooxygenase (pMMO) is an integral membrane metalloenzyme that oxidizes methane to methanol in methanotrophic bacteria, organisms that live on methane gas as their sole carbon source. Understanding pMMO function has important implications for bioremediation applications and for the development of new, environmentally friendly catalysts for the direct conversion of methane to methanol. Crystal structures of pMMOs from three different methanotrophs reveal a trimeric architecture, consisting of three copies each of the pmoB, pmoA, and pmoC subunits. There are three distinct metal centers in each protomer of the trimer, mononuclear and dinuclear copper sites in the periplasmic regions of pmoB and a mononuclear site within the membrane that can be occupied by copper or zinc. Various models for the pMMO active site have been proposed within these structural constraints, including dicopper, tricopper, and diiron centers. Biochemical and spectroscopic data on pMMO and recombinant soluble fragments, denoted spmoB proteins, indicate that the active site involves copper and is located at the site of the dicopper center in the pmoB subunit. Initial spectroscopic evidence for O(2) binding at this site has been obtained. Despite these findings, questions remain about the active site identity and nuclearity and will be the focus of future studies.
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Affiliation(s)
- Megen A. Culpepper
- Departments of Molecular Biosciences and of Chemistry, Northwestern University, Evanston, IL 60208, USA
| | - Amy C. Rosenzweig
- Departments of Molecular Biosciences and of Chemistry, Northwestern University, Evanston, IL 60208, USA
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30
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Molecular mechanism of anaerobic ammonium oxidation. Nature 2011; 479:127-30. [DOI: 10.1038/nature10453] [Citation(s) in RCA: 562] [Impact Index Per Article: 43.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2011] [Accepted: 08/12/2011] [Indexed: 11/08/2022]
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Hydrocarbon monooxygenase in Mycobacterium: recombinant expression of a member of the ammonia monooxygenase superfamily. ISME JOURNAL 2011; 6:171-82. [PMID: 21796219 DOI: 10.1038/ismej.2011.98] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The copper membrane monooxygenases (CuMMOs) are an important group of enzymes in environmental science and biotechnology. Areas of relevance include the development of green chemistry for sustainable exploitation of methane (CH(4)) reserves, remediation of chlorinated hydrocarbon contamination and monitoring human impact in the biogeochemical cycles of CH(4) and nitrogen. Challenges for all these applications are that many aspects of the ecology, physiology and structure-function relationships in the CuMMOs are inadequately understood. Here, we describe genetic and physiological characterization of a novel member of the CuMMO family that has an unusual physiological substrate range (C(2)-C(4) alkanes) and a distinctive bacterial host (Mycobacterium). The Mycobacterial CuMMO genes (designated hmoCAB) were amenable to heterologous expression in M. smegmatis-this is the first example of recombinant expression of a complete and highly active CuMMO enzyme. The apparent specific activity of recombinant cells containing hmoCAB ranged from 2 to 3 nmol min(-1) per mg protein on ethane, propane and butane as substrates, and the recombinants could also attack ethene, cis-dichloroethene and 1,2-dichloroethane. No detectable activity of recombinants or wild-type strains was seen with methane. The specific inhibitor allylthiourea strongly inhibited growth of wild-type cells on C(2)-C(4) alkanes, and omission of copper from the medium had a similar effect, confirming the physiological role of the CuMMO for growth on alkanes. The hydrocarbon monooxygenase provides a new model for studying this important enzyme family, and the recombinant expression system will enable biochemical and molecular biological experiments (for example, site-directed mutagenesis) that were previously not possible.
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Gilch S, Meyer O, Schmidt I. Electron paramagnetic studies of the copper and iron containing soluble ammonia monooxygenase from Nitrosomonas europaea. Biometals 2010; 23:613-22. [DOI: 10.1007/s10534-010-9308-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2009] [Accepted: 02/12/2010] [Indexed: 11/28/2022]
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Gilch S, Meyer O, Schmidt I. A soluble form of ammonia monooxygenase in Nitrosomonas europaea. Biol Chem 2009; 390:863-73. [DOI: 10.1515/bc.2009.085] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
AbstractAmmonia monooxygenase (AMO) ofNitrosomonas europaeais a metalloenzyme that catalyzes the oxidation of ammonia to hydroxylamine. This study shows that AMO resides in the cytoplasm of the bacteria in addition to its location in the membrane and is distributed approximately equally in both subcellular fractions. AMO in both fractions catalyzes the oxidation of ammonia and binds [14C]acetylene, a mechanism-based inhibitor which specifically interacts with catalytically active AMO. Soluble AMO was purified 12-fold to electrophoretic homogeneity with a yield of 8%. AMO has a molecular mass of approximately 283 kDa with subunits of ca. 27 kDa (α-subunit, AmoA), ca. 42 kDa (β-subunit, AmoB), and ca. 24 kDa (γ-subunit, cytochromec1) in an α3β3γ3sub-unit structure. Different from the β-subunit of membrane-bound AMO, AmoB of soluble AMO possesses an N-terminal signal sequence. AMO contains Cu (9.4±0.6 mol per mol AMO), Fe (3.9±0.3 mol per mol AMO), and Zn (0.5 to 2.6 mol per mol AMO). Upon reduction the visible absorption spectrum of AMO reveals absorption bands characteristic of cytochromec. Electron para-magnetic resonance spectroscopy of air-oxidized AMO at 50 K shows a paramagnetic signal originating from Cu2+and at 10 K a paramagnetic signal characteristic of heme-Fe.
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