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Ding K, Xu L, Chen Y, Li W, Chai X, Dai X, Wu B. Mechanistic insights into polyhydroxyalkanoate-enhanced denitrification capacity of microbial community: Evolution of community structure and intracellular electron transfer of nitrogen metabolism. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 856:159147. [PMID: 36183769 DOI: 10.1016/j.scitotenv.2022.159147] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2022] [Revised: 09/27/2022] [Accepted: 09/27/2022] [Indexed: 06/16/2023]
Abstract
Denitrification is the key driving force of nitrogen cycle in surface water and plays an important role in eutrophication water remediation. Compared with some other common carbon sources, such as glucose and sodium acetate, polyhydroxyalkanoates (PHAs) were found to have the distinguished advantages in screening specific denitrifying bacteria of natural surface water bodies. In this study, the large ensembles of taxa were obtained from surface water samples and then sub-cultured with PHA or glucose as the sole carbon source. The microbial community that could be screened by PHA was identified, and the environmental functions of these bacteria were analyzed. At the genus level, the main communities regulated by PHA included Pseudomonas (56.30 %), Acinetobacter (27.75 %), Flavobacterium (10.19 %) and Comamonas (3.14 %), which all had good denitrification ability. The changes in carbon source, nitrogen source and biomass (expressed by DNA) were simultaneously monitored when culturing the model strain (P. stuzeri) with PHA or glucose. Compared with the glucose group, less PHA was consumed to remove the same amount of nitrate within a shorter incubation time, and there was no significant difference in bacterial growth with PHA or glucose as the carbon source (glucose:ΔN:ΔC:ΔDNA = 1:18:0.072; PHA:ΔN:ΔC:ΔDNA = 1:11:0.063). PHA improved the denitrification efficiency by increasing the expression of NarGHI, NirB, NirK and NorB, i.e., the key enzymes in the denitrification process. In addition, PHA accelerated the assimilating rate of extracellular nitrate by bacteria through increasing the expression of NarK. Finally, PHA-regulated electron transfer during denitrification was studied by observing the changes in NADH and NAD+. PHA could use a large proportion of NADH to offer electrons for denitrification, which increased the rate of denitrification. Improved mechanistic insights into the PHA-enhanced denitrification capacity of the microbial community can provide novel options for the in-situ remediation of eutrophic surface water.
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Affiliation(s)
- Ke Ding
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China
| | - Linge Xu
- Hydrochina Huadong Engineering Corporation Limited, 201 Gaojiao Road, Hangzhou, 311122, China
| | - Yulin Chen
- Shanghai Municipal Engineering Design Institute (Group) Co., Ltd, 901 Zhongshan North 2nd Road, Shanghai 200092, China
| | - Wenxuan Li
- NUS Environmental Research Institute, National University of Singapore, 5A Engineering Drive 1, #02-01 T-Lab Building, 117411 Singapore, Singapore
| | - Xiaoli Chai
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China
| | - Xiaohu Dai
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China
| | - Boran Wu
- State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China.
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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: 96] [Impact Index Per Article: 32.0] [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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Ren T, Chi Y, Wang Y, Shi X, Jin X, Jin P. Diversified metabolism makes novel Thauera strain highly competitive in low carbon wastewater treatment. WATER RESEARCH 2021; 206:117742. [PMID: 34653797 DOI: 10.1016/j.watres.2021.117742] [Citation(s) in RCA: 79] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 08/01/2021] [Accepted: 10/04/2021] [Indexed: 06/13/2023]
Abstract
Thauera, as one of the core members of wastewater biological treatment systems, plays an important role in the process of nitrogen and phosphorus removal from low-carbon source sewage. However, there is a lack of systematic understanding of Thauera's metabolic pathway and genomics. Here we report on the newly isolated Thauera sp. RT1901, which is capable of denitrification using variety carbon sources including aromatic compounds. By comparing the denitrification processes under the conditions of insufficient, adequate and surplus carbon sources, it was found that strain RT1901 could simultaneously use soluble microbial products (SMP) and extracellular polymeric substances (EPS) as electron donors for denitrification. Strain RT1901 was also found to be a denitrifying phosphate accumulating bacterium, able to use nitrate, nitrite, or oxygen as electron acceptors during poly-β-hydroxybutyrate (PHB) catabolism. The annotated genome was used to reconstruct the complete nitrogen and phosphorus metabolism pathways of RT1901. In the process of denitrifying phosphorus accumulation, glycolysis was the only pathway for glycogen metabolism, and the glyoxylic acid cycle replaced the tricarboxylic acid cycle (TCA) to supplement the reduced energy. In addition, the abundance of conventional phosphorus accumulating bacteria decreased significantly and the removal rates of total nitrogen (TN) and chemical oxygen demand (COD) increased after the addition of RT1901 in the low carbon/nitrogen (C/N) ratio of anaerobic aerobic anoxic-sequencing batch reactor (AOA-SBR). This research indicated that the diverse metabolic capabilities of Thauera made it more competitive than other bacteria in the wastewater treatment system.
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Affiliation(s)
- Tong Ren
- School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an, Shaanxi Province 710055, China
| | - Yulei Chi
- School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an, Shaanxi Province 710055, China
| | - Yu Wang
- School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an, Shaanxi Province 710055, China
| | - Xuan Shi
- School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an, Shaanxi Province 710055, China
| | - Xin Jin
- School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an, Shaanxi Province 710055, China
| | - Pengkang Jin
- School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an, Shaanxi Province 710055, China; School of Human Settlements and Civil Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi Province 710049, China.
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Yang J, Feng L, Pi S, Cui D, Ma F, Zhao HP, Li A. A critical review of aerobic denitrification: Insights into the intracellular electron transfer. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 731:139080. [PMID: 32417477 DOI: 10.1016/j.scitotenv.2020.139080] [Citation(s) in RCA: 96] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 04/04/2020] [Accepted: 04/26/2020] [Indexed: 05/23/2023]
Abstract
Aerobic denitrification is a novel biological nitrogen removal technology, which has been widely investigated as an alternative to the conventional denitrification and for its unique advantages. To fully comprehend aerobic denitrification, it is essential to clarify the regulatory mechanisms of intracellular electron transfer during aerobic denitrification. However, reports on intracellular electron transfer during aerobic denitrification are rather limited. Thus, the purpose of this review is to discuss the molecular mechanism of aerobic denitrification from the perspective of electron transfer, by summarizing the advancements in current research on electron transfer based on conventional denitrification. Firstly, the implication of aerobic denitrification is briefly discussed, and the status of current research on aerobic denitrification is summarized. Then, the occurring foundation and significance of aerobic denitrification are discussed based on a brief review of the key components involved in the electron transfer of denitrifying enzymes. Moreover, a strategy for enhancing the efficiency of aerobic denitrification is proposed on the basis of the regulatory mechanisms of denitrification enzymes. Finally, scientific outlooks are given for further investigation on aerobic denitrification in the future. This review could help clarify the mechanism of aerobic denitrification from the perspective of electron transfer.
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Affiliation(s)
- Jixian Yang
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, People's Republic of China
| | - Liang Feng
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, People's Republic of China
| | - Shanshan Pi
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, People's Republic of China
| | - Di Cui
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, People's Republic of China; Engineering Research Center for Medicine, College of Pharmacy, Harbin University of Commerce, Harbin 150076, People's Republic of China
| | - Fang Ma
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, People's Republic of China
| | - He-Ping Zhao
- College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, People's Republic of China
| | - Ang Li
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, People's Republic of China.
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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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6
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Chen M, Zhou XF, Yu YQ, Liu X, Zeng RJX, Zhou SG, He Z. Light-driven nitrous oxide production via autotrophic denitrification by self-photosensitized Thiobacillus denitrificans. ENVIRONMENT INTERNATIONAL 2019; 127:353-360. [PMID: 30954721 DOI: 10.1016/j.envint.2019.03.045] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2019] [Revised: 02/27/2019] [Accepted: 03/19/2019] [Indexed: 06/09/2023]
Abstract
N2O (Nitrous oxide, a booster oxidant in rockets) has attracted increasing interest as a means of enhancing energy production, and it can be produced by nitrate (NO3-) reduction in NO3--loading wastewater. However, conventional denitrification processes are often limited by the lack of bioavailable electron donors. In this study, we innovatively propose a self-photosensitized nonphototrophic Thiobacillus denitrificans (T. denitrificans-CdS) that is capable of NO3- reduction and N2O production driven by light. The system converted >72.1 ± 1.1% of the NO3--N input to N2ON, and the ratio of N2O-N in gaseous products was >96.4 ± 0.4%. The relative transcript abundance of the genes encoding the denitrifying proteins in T. denitrificans-CdS after irradiation was significantly upregulated. The photoexcited electrons acted as the dominant electron sources for NO3- reduction by T. denitrificans-CdS. This study provides the first proof of concept for sustainable and low-cost autotrophic denitrification to generate N2O driven by light. The findings also have strong implications for sustainable environmental management because the sunlight-triggered denitrification reaction driven by nonphototrophic microorganisms may widely occur in nature, particularly in a semiconductive mineral-enriched aqueous environment.
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Affiliation(s)
- Man Chen
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Xiao-Fang Zhou
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Yu-Qing Yu
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Xing Liu
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Raymond Jian-Xiong Zeng
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Shun-Gui Zhou
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China.
| | - Zhen He
- Department of Civil and Environmental Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
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7
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Xu H, Jin R, Zhang C, Wu Y, Wang X. Isolation and identification of an aerobic denitrifying phosphorus removing bacteria and analysis of the factors influencing denitrification and phosphorus removal. WATER SCIENCE AND TECHNOLOGY : A JOURNAL OF THE INTERNATIONAL ASSOCIATION ON WATER POLLUTION RESEARCH 2018; 78:2288-2296. [PMID: 30699080 DOI: 10.2166/wst.2018.514] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Excessive emission of plant nutrients (such as nitrogen and phosphorus) into the water body can induce eutrophication. Therefore, how to control eutrophic water efficiently and economically is very important. In the paper, highly efficient aerobic denitrifying phosphorus removing J16 bacteria was isolated from the activated sludge of an aerobic bioreactor in Taiyuan municipal wastewater treatment plant by using the blue-white spot screening method, an aerobic phosphorus absorption test, nitrate reduction test, nitrogen removal experiments, and plate coating and streaking methods. Through 16S rDNA gene homology comparison and physiological and biochemical identification, the J16 strain was preliminarily identified as Escherichia coli, with a sequence similarity of 99%. The 16S rDNA sequence of strain J16 was submitted to GenBank (accession number: MF667015). The effect of temperature, pH, percentage of inoculum and phosphate-P (PO4 3--P) concentration on denitrification and phosphorus removal efficiency was investigated through a single-factor experiment. The optimum conditions of the J16 strain for denitrification and phosphorus removal were as follows: 30°C, neutral or weak alkaline (pH: 7.2-8), and 3% of inoculum, respectively. The denitrification and phosphorus removal efficiency of strain J16 was the highest when PO4 3--P and nitrate-N(NO3 --N) concentrations were 8.9 and 69.31 mg/L, and the removal were 96.03% and 94.55%, respectively. In addition, strain J16 could reduce phosphoric acid to phosphine (PH3) and remove some phosphorus under hypoxia conditions. This is the first study to report the involvement of Escherichia coli in nitrogen and phosphorus removal under aerobic and hypoxia conditions. Based on the above results, the strain J16 can effectively remove nitrogen and phosphorus, and will be utilized in enhancing treatment of nitrogen and phosphorus-containing industrial wastewater and phosphorus reclamation.
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Affiliation(s)
- Hongying Xu
- School of Environment and Safety, Taiyuan University of Science and Technology, Taiyuan, China E-mail:
| | - Ru Jin
- School of Environment and Safety, Taiyuan University of Science and Technology, Taiyuan, China E-mail:
| | - Chan Zhang
- School of Environment and Safety, Taiyuan University of Science and Technology, Taiyuan, China E-mail:
| | - Yupeng Wu
- School of Environment and Safety, Taiyuan University of Science and Technology, Taiyuan, China E-mail:
| | - Xiaohui Wang
- School of Environment and Safety, Taiyuan University of Science and Technology, Taiyuan, China E-mail:
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8
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Sun H, Yang Z, Wei C, Wu W. Nitrogen removal performance and functional genes distribution patterns in solid-phase denitrification sub-surface constructed wetland with micro aeration. BIORESOURCE TECHNOLOGY 2018; 263:223-231. [PMID: 29747099 DOI: 10.1016/j.biortech.2018.04.078] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2018] [Revised: 04/18/2018] [Accepted: 04/20/2018] [Indexed: 06/08/2023]
Abstract
An up-flow vertical flow constructed wetland (AC-VFCW) filled with ceramsite and 5% external carbon source poly(3-hydroxybutyrate-hydroxyvalerate) (PHBV) as substrate was set for nitrogen removal with micro aeration. Simultaneous nitrification and denitrification process was observed with 90.4% NH4+-N and 92.1% TN removal efficiencies. Nitrification and denitrification genes were both preferentially enriched on the surface of PHBV. Nitrogen transformation along the flow direction showed that NH4+-N was oxidized to NO3--N at the lowermost 10 cm of the substrate and NO3--N gradually degraded over the depth. AmoA gene was more enriched at -10 and -50 cm layers. NirS gene was the dominant functional gene at the bottom layer with the abundance of 2.05 × 107 copies g-1 substrate while nosZ gene was predominantly abundant with 7.51 × 106 and 2.64 × 106 copies g-1 substrate at the middle and top layer, respectively, indicating that functional division of dominant nitrogen functional genes forms along the flow direction in AC-VFCW.
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Affiliation(s)
- Haimeng Sun
- Department of Environmental Science, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, PR China
| | - Zhongchen Yang
- Department of Environmental Science, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, PR China
| | - Caijie Wei
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, PR China
| | - Weizhong Wu
- Department of Environmental Science, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, PR China.
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Zhao J, Wu J, Li X, Wang S, Hu B, Ding X. The Denitrification Characteristics and Microbial Community in the Cathode of an MFC with Aerobic Denitrification at High Temperatures. Front Microbiol 2017; 8:9. [PMID: 28154554 PMCID: PMC5243800 DOI: 10.3389/fmicb.2017.00009] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Accepted: 01/03/2017] [Indexed: 11/13/2022] Open
Abstract
Microbial fuel cells (MFCs) have attracted much attention due to their ability to generate electricity while treating wastewater. The performance of a double-chamber MFC with simultaneous nitrification and denitrification (SND) in the cathode for treating synthetic high concentration ammonia wastewater was investigated at different dissolved oxygen (DO) concentrations and high temperatures. The results showed that electrode denitrification and traditional heterotrophic denitrification co-existed in the cathode chamber. Electrode denitrification by aerobic denitrification bacterium (ADB) is beneficial for achieving a higher voltage of the MFC at high DO concentrations (3.0–4.2 mg/L), while traditional heterotrophic denitrification is conducive to higher total nitrogen (TN) removal at low DO (0.5–1.0 mg/L) concentrations. Under high DO conditions, the nitrous oxide production and TN removal efficiency were higher with a 50 Ω external resistance than with a 100 Ω resistance, which demonstrated that electrode denitrification by ADB occurred in the cathode of the MFC. Sufficient electrons were inferred to be provided by the electrode to allow ADB survival at low carbon:nitrogen ratios (≤0.3). Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) results showed that increasing the DO resulted in a change of the predominant species from thermophilic autotrophic nitrifiers and facultative heterotrophic denitrifiers at low DO concentrations to thermophilic ADB at high DO concentrations. The predominant phylum changed from Firmicutes to Proteobacteria, and the predominant class changed from Bacilli to Alpha, Beta, and Gamma Proteobacteria.
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Affiliation(s)
- Jianqiang Zhao
- School of Environmental Science and Engineering, Chang'an UniversityXi'an, China; Key Laboratory of Subsurface Hydrology and Ecological Effect in Arid Region of Ministry of EducationXi'an, China
| | - Jinna Wu
- School of Environmental Science and Engineering, Chang'an University Xi'an, China
| | - Xiaoling Li
- School of Civil Engineering, Chang'an University Xi'an, China
| | - Sha Wang
- School of Environmental Science and Engineering, Chang'an University Xi'an, China
| | - Bo Hu
- School of Civil Engineering, Chang'an University Xi'an, China
| | - Xiaoqian Ding
- School of Environmental Science and Engineering, Chang'an University Xi'an, China
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Qu Z, Bakken LR, Molstad L, Frostegård Å, Bergaust LL. Transcriptional and metabolic regulation of denitrification in Paracoccus denitrificans allows low but significant activity of nitrous oxide reductase under oxic conditions. Environ Microbiol 2016; 18:2951-63. [PMID: 26568281 DOI: 10.1111/1462-2920.13128] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Revised: 11/02/2015] [Accepted: 11/08/2015] [Indexed: 11/27/2022]
Abstract
Oxygen is known to repress denitrification at the transcriptional and metabolic levels. It has been a common notion that nitrous oxide reductase (N2 OR) is the most sensitive enzyme among the four N-oxide reductases involved in denitrification, potentially leading to increased N2 O production under suboxic or fluctuating oxygen conditions. We present detailed gas kinetics and transcription patterns from batch culture experiments with Paracoccus denitrificans, allowing in vivo estimation of e(-) -flow to O2 and N2 O under various O2 regimes. Transcription of nosZ took place concomitantly with that of narG under suboxic conditions, whereas transcription of nirS and norB was inhibited until O2 levels approached 0 μM in the liquid. Catalytically functional N2 OR was synthesized and active in aerobically raised cells transferred to vials with 7 vol% O2 in headspace, but N2 O reduction rates were 10 times higher when anaerobic pre-cultures were subjected to the same conditions. Upon oxygen exposure, there was an incomplete and transient inactivation of N2 OR that could be ascribed to its lower ability to compete for electrons compared with terminal oxidases. The demonstrated reduction of N2 O at high O2 partial pressure and low N2 O concentrations by a bacterium not known as a typical aerobic denitrifier may provide one clue to the understanding of why some soils appear to act as sinks rather than sources for atmospheric N2 O.
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Affiliation(s)
- Zhi Qu
- Department of Environmental Sciences, Norwegian University of Life Sciences, PO Box 5003, N-1432, Ås, Norway
| | - Lars R Bakken
- Department of Environmental Sciences, Norwegian University of Life Sciences, PO Box 5003, N-1432, Ås, Norway
| | - Lars Molstad
- Department of Environmental Sciences, Norwegian University of Life Sciences, PO Box 5003, N-1432, Ås, Norway
| | - Åsa Frostegård
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, PO Box 5003, N-1432, Ås, Norway
| | - Linda L Bergaust
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, PO Box 5003, N-1432, Ås, Norway.
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11
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Zhang Y, Ji G, Wang R. Genetic associations as indices of nitrogen cycling rates in an aerobic denitrification biofilter used for groundwater remediation. BIORESOURCE TECHNOLOGY 2015; 194:49-56. [PMID: 26185925 DOI: 10.1016/j.biortech.2015.07.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Revised: 07/01/2015] [Accepted: 07/05/2015] [Indexed: 06/04/2023]
Abstract
An aerobic denitrification biofilter (ADB) for groundwater remediation was developed with high removal efficiencies (total nitrogen (TN): 82.3-95.8%; NO3(-)-N: 93.2-98.2%). Nitrate (NO3(-)-N) transformation rates stabilized between 21.0 and 23.4 g/(m(3) h), whereas nitrite (NO2(-)-N) and ammonium (NH4(+)-N) transformation rates remained less than 6.0 g/(m(3) h) as the dissolved oxygen (DO) level increased from 1.0 mg/L to 6.0 mg/L. Nitric oxide (NO) and nitrous oxide (N2O) accumulated with great fluctuations (NO: 0-1.6×10(-3) g/(m(3) h); N2O: 0.1-1.1g/(m(3)h)) throughout the experiment. This study suggested that gene associations reflect quantitative relationships with aerobic denitrification rates and can provide useful information regarding aerobic denitrification processes in groundwater. Especially, the qnorB/nosZ ratio acts as the main driver for NO3(-)-N and NH4(+)-N transformation, while the qnorB/nosZ ratio followed by the (nirS+nirK)/nosZ ratio serve a dominant role in the accumulation of N2O and NO.
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Affiliation(s)
- Yan Zhang
- Key Laboratory of Water and Sediment Sciences, Ministry of Education, Department of Environmental Engineering, Peking University, Beijing 100871, China
| | - Guodong Ji
- Key Laboratory of Water and Sediment Sciences, Ministry of Education, Department of Environmental Engineering, Peking University, Beijing 100871, China.
| | - Rongjing Wang
- Key Laboratory of Water and Sediment Sciences, Ministry of Education, Department of Environmental Engineering, Peking University, Beijing 100871, China
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Identification of a Highly Efficient Aerobic Denitrifying Bacterium in SBR and Denitrification Optimization. ACTA ACUST UNITED AC 2014. [DOI: 10.4028/www.scientific.net/amr.955-959.376] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Aerobic denitrification process is attracted more attention to enhance nitrogen removal technology. Aerobic denitrifying bacteria present excelled abilities with fast growth rate and denitrifying speed, though they are not dominant in most practical processes. A high-efficiency strain was enriched in SBR from aerobic activated sludge by the way of intermittent aeration and continuous aeration combination. The strain was determined toPseudomonasstutzeriT13 with ability of TN removal 90% and nitrate removal 97%. The limiting factors for aerobic denitrifying efficiency were optimized to temperature=31°C,pH=7.11 and DO=2.5 mg/L using response surface methodology. A total of 32 genes are related to nitrogen removal in strain T13. And 10 related to nitrate reductase, especially including 3 genes encoding the periplasmic nitrate reductase, playing important role to aerobic denitrification. It gave good understanding to supply effective technological supports for aerobic denitrification process.
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13
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Genome sequence of a highly efficient aerobic denitrifying bacterium, Pseudomonas stutzeri T13. J Bacteriol 2012; 194:5720. [PMID: 23012292 DOI: 10.1128/jb.01376-12] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pseudomonas stutzeri T13 is a highly efficient aerobic denitrifying bacterium. Information about the genome of this aerobic denitrifying bacterium has been limited until now. We present the draft genome of P. stutzeri T13. The results could provide further insight into the aerobic denitrification mechanism in strain T13.
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14
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Dalsgaard T, Revsbech NP. Regulating factors of denitrification in trickling filter biofilms as measured with the oxygen/nitrous oxide microsensor. FEMS Microbiol Ecol 2011. [DOI: 10.1111/j.1574-6941.1992.tb01651.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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15
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Meyer A, Bergmann J, Butterbach-Bahl K, Bruggemann N. A new ¹⁵N tracer method to determine N turnover and denitrification of Pseudomonas stutzeri. ISOTOPES IN ENVIRONMENTAL AND HEALTH STUDIES 2010; 46:409-421. [PMID: 21058101 DOI: 10.1080/10256016.2010.528840] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Although denitrification is one of the key processes of ecosystem N turnover, the understanding of the regulation of the denitrification pathway is still limited due to the lack of feasible methods for the quantification of N₂ formation. Based on the previously developed isotope pairing method, we present a new in vitro ¹⁵N tracer method for the quantification of N₂ released from denitrification by bacterial cultures. The application of the new method was enabled by replacing the background air in the sample flasks with a gas mixture of He and O₂ with an approximately 50-fold reduced N₂ background (1.7% v/v), allowing for a direct and sensitive quantification of N₂ formation with isotope-ratio mass spectrometry after ¹⁵N-labelling on the one hand, but leaving the method relatively insensitive to intrusion of ambient N₂ on the other hand. The method was tested on bacterial cultures of Pseudomonas stutzeri grown at different oxygen levels. Additionally, NO and N₂O formation were determined with a chemoluminescence analyser and a gas chromatograph, respectively. Following labelling with ¹⁵N-ammonium and ¹⁵N-nitrate, it could be shown that P. stutzeri used ammonium preferably for biomass build-up, and nitrate preferably as electron acceptor. Between 84-107% of the total available N could be recovered. Due to the high sensitivity of the new method only low levels of ¹⁵N tracer were necessary, minimising substrate-induced effects and making this method also an appropriate tool for the use on soil cores. By that it offers a new method for studying denitrification in terrestrial ecosystems.
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Affiliation(s)
- Astrid Meyer
- Atmospheric Environmental Research Division (IMK-IFU), Institute of Meteorology and Climate Research, Karlsruhe Institute of Technology, Garmisch-Partenkirchen, Germany
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16
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Baggs EM. A review of stable isotope techniques for N2O source partitioning in soils: recent progress, remaining challenges and future considerations. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2008; 22:1664-1672. [PMID: 18435506 DOI: 10.1002/rcm.3456] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Nitrous oxide is produced in soil during several processes, which may occur simultaneously within different micro-sites of the same soil. Stable isotope techniques have a crucial role to play in the attribution of N(2)O emissions to different microbial processes, through estimation (natural abundance, site preference) or quantification (enrichment) of processes based on the (15)N and (18)O signatures of N(2)O determined by isotope ratio mass spectrometry. These approaches have the potential to become even more powerful when linked with recent developments in secondary isotope mass spectrometry, with microbial ecology, and with modelling approaches, enabling sources of N(2)O to be considered at a wide range of scales and related to the underlying microbiology. Such source partitioning of N(2)O is inherently challenging, but is vital to close the N(2)O budget and to better understand controls on the different processes, with a view to developing appropriate management practices for mitigation of N(2)O. In this respect, it is essential that as many of the contributing processes as possible are considered in any study aimed at source attribution, as mitigation strategies for one process may not be appropriate for another. To aid such an approach, here the current state of the art is critically examined, remaining challenges are highlighted, and recommendations are made for future direction.
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Affiliation(s)
- E M Baggs
- School of Biological Sciences (Plant & Soil Science), University of Aberdeen, Cruickshank Building, St Machar Drive, Aberdeen AB24 3UU, UK.
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17
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Morley N, Baggs EM, Dörsch P, Bakken L. Production of NO, N2O and N2 by extracted soil bacteria, regulation by NO2(-) and O2 concentrations. FEMS Microbiol Ecol 2008; 65:102-12. [PMID: 18462397 DOI: 10.1111/j.1574-6941.2008.00495.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
The oxygen control of denitrification and its emission of NO/N2O/N2 was investigated by incubation of Nycodenz-extracted soil bacteria in an incubation robot which monitors O2, NO, N2O and N2 concentrations (in He+O2 atmosphere). Two consecutive incubations were undertaken to determine (1) the regulation of denitrification by O2 and NO2(-) during respiratory O2 depletion and (2) the effects of re-exposure to O2 of cultures with fully expressed denitrification proteome. Early denitrification was only detected (as NO and N2O) at <or=80 microM O2 in treatments with NO2(-), and the rates were three orders of magnitude lower than the rates observed after oxygen depletion (with N2 as the primary product). When re-exposed to O2, the cultures continued to denitrify (8-55% of the rates during the foregoing anoxic phase), but its main product was N2O. The N2O reductase activity recovered as oxygen was being depleted. The results suggest that expression of the denitrifying proteome may result in significant subsequent aerobic denitrification, and this has profound implications for the understanding and modelling of denitrification and N2O emission. Short anoxic spells caused by transient flooding during rainfall, could lead to subsequent unbalanced aerobic denitrification, in which N2O is a major end product.
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Affiliation(s)
- Nicholas Morley
- School of Biological Sciences, Plant and Soil Science, University of Aberdeen, Aberdeen, UK.
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18
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Ju LK, Chen F, Xia Q. Monitoring microaerobic denitrification of Pseudomonas aeruginosa by online NAD(P)H fluorescence. J Ind Microbiol Biotechnol 2005; 32:622-8. [PMID: 16228188 DOI: 10.1007/s10295-005-0035-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2004] [Accepted: 07/03/2005] [Indexed: 10/25/2022]
Abstract
Defined as the transition conditions in which the organism(s) performs simultaneous aerobic and anaerobic respiration or fermentation, microaerobic conditions are commonly present in the nature. Microaerobic metabolism of microorganisms is however poorly characterized. Being extremely sensitive to the change in cellular electron-accepting mechanisms, NAD(P)H fluorescence provides a useful ways for online monitoring of microaerobic metabolism. Its application to studies of microbial nitrate respiration and particularly, denitrification of Pseudomonas aeruginosa is reviewed here, centering on four topics: (1) online monitoring of anaerobic nitrate respiration by NAD(P)H fluorescence, (2) effects of denitrification on P. aeruginosa phenotypes, (3) microaerobic denitrification of P. aeruginosa in continuous culture, and (4) correlation between NAD(P)H fluorescence and denitrification-to-respiration ratio. Online NAD(P)H fluorescence is shown to sensitively detect the changes of cellular metabolism. For example, it revealed the intermediate nitrite accumulation in C-limited Escherichia coli performing anaerobic nitrate respiration via dissimilative ammonification, by exhibiting two-stage profiles with intriguing fluorescence oscillation. When applied to continuous culture studies of P. aeruginosa (ATCC 9027), the online fluorescence helped to identify that the bacterium conducted denitrification even at DO > 1 mg/l. In addition, the fluorescence profile showed a unique correlation with the fraction of electrons accepted by denitrification (out of all the electrons accepted by aerobic and anaerobic respiration). The applicability of online NAD(P)H fluorescence in monitoring and quantitatively describing the sensitive microaerobic state of microorganisms is clearly demonstrated.
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Affiliation(s)
- Lu-Kwang Ju
- Department of Chemical Engineering, The University of Akron, Akron, OH 44325-3906, USA.
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19
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Chen F, Xia Q, Ju LK. Aerobic denitrification of Pseudomonas aeruginosa monitored by online NAD(P)H fluorescence. Appl Environ Microbiol 2004; 69:6715-22. [PMID: 14602632 PMCID: PMC262322 DOI: 10.1128/aem.69.11.6715-6722.2003] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Continuous cultures of Pseudomonas aeruginosa (ATCC 9027) maintained at different dissolved oxygen concentrations (DO) were studied for the effects of DO on various culture properties, especially aerobic respiration and denitrification. The DO was varied from 0 mg/liter (completely anoxic conditions) to 1.3 mg/liter and measured with optical sensors that could accurately determine very low DO based on oxygen-quenched luminescence. The strain was found to perform aerobic denitrification; while the specific rate decreased with increasing DO, denitrification persisted at approximately 1/8 of the maximum rate (1.7 mmol/g of cells/h) even at relatively high DO (1 to 1.3 mg/liter). In the presence of nitrate, the culture's Monod half-rate saturation constant for O(2) was very small, <0.1 mg/liter. Aerobic denitrification appeared to function as an electron-accepting mechanism supplementary to or competitive with aerobic respiration. The shift of the culture's respiratory mechanism was also clearly detected with a fluorometer targeting intracellular NAD(P)H, i.e., the reduced forms of the NAD(P) coenzymes. Comparatively, the NAD(P)H fluorescence under the anoxic, denitrifying conditions (NFU(DN)) was highest, that under fully aerobic conditions (NFU(OX)) was lowest, and that under conditions in which both denitrification and aerobic respiration occurred (NFU) was intermediate. Representing a quantitative measure of the culture's "fractional approach" to the fully denitrifying state, the normalized fraction (NFU - NFU(OX))/(NFU(DN) - NFU(OX)) was correlated with DO and the calculated fraction of electrons accepted by denitrification. The NFU fraction decreased with increasing DO, following an empirical exponential relationship. The fraction of denitrification-accepted electrons increased with the NFU fraction: the increase was gradual and approximately linear at DO of >/==" BORDER="0">0.1 mg/liter but much sharper at lower DO. Online NAD(P)H fluorescence was demonstrated as a feasible technique for effective monitoring and quantitative description of the microaerobic state of microorganisms.
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Affiliation(s)
- Fan Chen
- Department of Chemical Engineering, The University of Akron, Akron, Ohio 44325, USA
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20
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Zuo L, Pasniciuc S, Wright VP, Merola AJ, Clanton TL. Sources for superoxide release: lessons from blockade of electron transport, NADPH oxidase, and anion channels in diaphragm. Antioxid Redox Signal 2003; 5:667-75. [PMID: 14580324 DOI: 10.1089/152308603770310347] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Isolated diaphragm releases low levels of superoxide (O2*-) at rest and much higher levels during heat stress. The molecular source is unknown. The hypothesis was tested that heat stress stimulates mitochondrial complex activity or NADPH oxidases, resulting in increased O2*- release. The mitochondria within intact rat diaphragm were inhibited at complex I (amobarbital or rotenone) or complex I and II (rotenone plus thenoyltrifluoroacetone). NADPH oxidases were blocked by diphenyliodonium. None of these treatments inhibited O2*- release. Conversely, most blockers stimulated O2*- release. As intracellular O2*- generators require a mechanism for O2*- transport across the membrane, anion channel blockers, probenecid and 4,4'-diisothiocyanato-stilbene-2,2'-disulfonic acid, were also tested. Neither blocker had any inhibitory effect on O2*- release. These results suggest that O2*- released from diaphragm is not directly dependent on mitochondrial complex activity and that it is not a reflection of passive diffusion of O2*- through anion channels. Although the molecular source for extracellular O2*- remains elusive, it is clearly sensitive to temperature and conditions of "chemical hypoxia" induced by partial or complete mitochondrial inhibition.
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Affiliation(s)
- Li Zuo
- The Ohio State University Medical Centre, Department of Internal Medicine, Dorothy M. Davis Heart & Lung Research Institute, Division of Pulmonary and Critical Care Medicine, Columbus, OH 43210, USA
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21
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Rasmussen T, Berks BC, Butt JN, Thomson AJ. Multiple forms of the catalytic centre, CuZ, in the enzyme nitrous oxide reductase from Paracoccus pantotrophus. Biochem J 2002; 364:807-15. [PMID: 12049645 PMCID: PMC1222630 DOI: 10.1042/bj20020055] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Nitrous oxide reductase catalyses the reduction of nitrous oxide to dinitrogen at a unique tetranuclear copper site, called Cu(Z), which has a central inorganic sulphide ligand. Limited incubation with oxygen during the preparation of nitrous oxide reductase from Paracoccus pantotrophus results in changed redox properties of the catalytic centre by comparison with anaerobic preparations. While the anaerobically purified enzyme has a catalytic centre which performs a single electron step at a midpoint potential of E(m)=+60 mV versus the standard hydrogen electrode (n=1), the altered centre shows no redox change under similar experimental conditions. Spectroscopic properties of this 'redox fixed' centre are similar to spectra of the reduced 'redox active' form of CuZ, although the positions and intensities of a number of transitions are changed in the optical spectrum. These observations are interpreted in terms of two forms of the catalytic centre, called CuZ and CuZ*. The structural relationship between these forms is unclear. EPR and magnetic circular dichroism spectra suggest that the basic Cu4S structure is common to both. Curiously, steady-state activity of the aerobic enzyme preparation is slightly increased despite the fact the catalytic centre does not undergo detectable redox changes.
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Affiliation(s)
- Tim Rasmussen
- Centre for Metalloprotein Spectroscopy and Biology, School of Biological Sciences, University of East Anglia, Norwich, NR4 7TJ, UK
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22
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Murrant CL, Reid MB. Detection of reactive oxygen and reactive nitrogen species in skeletal muscle. Microsc Res Tech 2001; 55:236-48. [PMID: 11748862 DOI: 10.1002/jemt.1173] [Citation(s) in RCA: 122] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are usually identified with pathological states and mediators of cellular injury. However, over the last decade ROS and RNS have been identified in skeletal muscle under physiological conditions. Detection of ROS and RNS production by skeletal muscle cells is fundamental to the problem of differentiating between physiological and pathological levels. The goal of this paper is to review the techniques that have been used to detect ROS and RNS in skeletal muscle. Electron spin resonance, fluorescent assays, cyotchrome c reduction, chemiluminescence, hydroxylation of salicylate, and nitration of phenylalanine are some of the assay systems that have been used thus far. A large body of evidence now indicates that ROS and RNS are continually produced by many different skeletal muscle types studied in vivo, in situ, and in vitro. Under resting conditions, ROS and RNS are detectable in both intracellular and extracellular compartments. Production increases during both non-fatiguing and fatiguing muscle contractions. In the absence of disease, the individual molecular species detected in skeletal muscle include parent radicals for the ROS and RNS cascades: superoxide anions and nitric oxide. Both are generated at rates estimated to range from pmol-to-nmol/mg muscle/minute. Evidence indicates that hydrogen peroxide, hydroxyl radicals, and peroxynitrite are also present under physiological conditions. However, the molecular species that mediate specific biological effects remains largely undetermined, as do the sources of ROS and RNS within muscle fibers. Eventual delineation of the mechanisms whereby ROS and RNS regulate cellular function will hinge on our understanding of the production and distribution of ROS and RNS within skeletal muscle.
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Affiliation(s)
- C L Murrant
- Department of Pharmacology and Physiology, University of Rochester, Rochester, New York 14642, USA.
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23
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Gupta A, Gupta S. Simultaneous carbon and nitrogen removal in a mixed culture aerobic RBC biofilm. WATER RESEARCH 1999; 33:555-561. [DOI: 10.1016/s0043-1354(98)00206-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2023]
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24
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Baker SC, Ferguson SJ, Ludwig B, Page MD, Richter OM, van Spanning RJ. Molecular genetics of the genus Paracoccus: metabolically versatile bacteria with bioenergetic flexibility. Microbiol Mol Biol Rev 1998; 62:1046-78. [PMID: 9841665 PMCID: PMC98939 DOI: 10.1128/mmbr.62.4.1046-1078.1998] [Citation(s) in RCA: 151] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Paracoccus denitrificans and its near relative Paracoccus versutus (formerly known as Thiobacilllus versutus) have been attracting increasing attention because the aerobic respiratory system of P. denitrificans has long been regarded as a model for that of the mitochondrion, with which there are many components (e.g., cytochrome aa3 oxidase) in common. Members of the genus exhibit a great range of metabolic flexibility, particularly with respect to processes involving respiration. Prominent examples of flexibility are the use in denitrification of nitrate, nitrite, nitrous oxide, and nitric oxide as alternative electron acceptors to oxygen and the ability to use C1 compounds (e.g., methanol and methylamine) as electron donors to the respiratory chains. The proteins required for these respiratory processes are not constitutive, and the underlying complex regulatory systems that regulate their expression are beginning to be unraveled. There has been uncertainty about whether transcription in a member of the alpha-3 Proteobacteria such as P. denitrificans involves a conventional sigma70-type RNA polymerase, especially since canonical -35 and -10 DNA binding sites have not been readily identified. In this review, we argue that many genes, in particular those encoding constitutive proteins, may be under the control of a sigma70 RNA polymerase very closely related to that of Rhodobacter capsulatus. While the main focus is on the structure and regulation of genes coding for products involved in respiratory processes in Paracoccus, the current state of knowledge of the components of such respiratory pathways, and their biogenesis, is also reviewed.
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Affiliation(s)
- S C Baker
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom.
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25
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Gupta A. Thiosphaera pantotropha: a sulphur bacterium capable of simultaneous heterotrophic nitrification and aerobic denitrification. Enzyme Microb Technol 1997. [DOI: 10.1016/s0141-0229(97)00070-7] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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26
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Abstract
Denitrification is a distinct means of energy conservation, making use of N oxides as terminal electron acceptors for cellular bioenergetics under anaerobic, microaerophilic, and occasionally aerobic conditions. The process is an essential branch of the global N cycle, reversing dinitrogen fixation, and is associated with chemolithotrophic, phototrophic, diazotrophic, or organotrophic metabolism but generally not with obligately anaerobic life. Discovered more than a century ago and believed to be exclusively a bacterial trait, denitrification has now been found in halophilic and hyperthermophilic archaea and in the mitochondria of fungi, raising evolutionarily intriguing vistas. Important advances in the biochemical characterization of denitrification and the underlying genetics have been achieved with Pseudomonas stutzeri, Pseudomonas aeruginosa, Paracoccus denitrificans, Ralstonia eutropha, and Rhodobacter sphaeroides. Pseudomonads represent one of the largest assemblies of the denitrifying bacteria within a single genus, favoring their use as model organisms. Around 50 genes are required within a single bacterium to encode the core structures of the denitrification apparatus. Much of the denitrification process of gram-negative bacteria has been found confined to the periplasm, whereas the topology and enzymology of the gram-positive bacteria are less well established. The activation and enzymatic transformation of N oxides is based on the redox chemistry of Fe, Cu, and Mo. Biochemical breakthroughs have included the X-ray structures of the two types of respiratory nitrite reductases and the isolation of the novel enzymes nitric oxide reductase and nitrous oxide reductase, as well as their structural characterization by indirect spectroscopic means. This revealed unexpected relationships among denitrification enzymes and respiratory oxygen reductases. Denitrification is intimately related to fundamental cellular processes that include primary and secondary transport, protein translocation, cytochrome c biogenesis, anaerobic gene regulation, metalloprotein assembly, and the biosynthesis of the cofactors molybdopterin and heme D1. An important class of regulators for the anaerobic expression of the denitrification apparatus are transcription factors of the greater FNR family. Nitrate and nitric oxide, in addition to being respiratory substrates, have been identified as signaling molecules for the induction of distinct N oxide-metabolizing enzymes.
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Affiliation(s)
- W G Zumft
- Lehrstuhl für Mikrobiologie, Universität Fridericiana, Karlsruhe, Germany
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27
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Conrad R. Soil microorganisms as controllers of atmospheric trace gases (H2, CO, CH4, OCS, N2O, and NO). Microbiol Rev 1996; 60:609-40. [PMID: 8987358 PMCID: PMC239458 DOI: 10.1128/mr.60.4.609-640.1996] [Citation(s) in RCA: 360] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Production and consumption processes in soils contribute to the global cycles of many trace gases (CH4, CO, OCS, H2, N2O, and NO) that are relevant for atmospheric chemistry and climate. Soil microbial processes contribute substantially to the budgets of atmospheric trace gases. The flux of trace gases between soil and atmosphere is usually the result of simultaneously operating production and consumption processes in soil: The relevant processes are not yet proven with absolute certainty, but the following are likely for trace gas consumption: H2 oxidation by abiontic soil enzymes; CO cooxidation by the ammonium monooxygenase of nitrifying bacteria; CH4 oxidation by unknown methanotrophic bacteria that utilize CH4 for growth; OCS hydrolysis by bacteria containing carbonic anhydrase; N2O reduction to N2 by denitrifying bacteria; NO consumption by either reduction to N2O in denitrifiers or oxidation to nitrate in heterotrophic bacteria. Wetland soils, in contrast to upland soils are generally anoxic and thus support the production of trace gases (H2, CO, CH4, N2O, and NO) by anaerobic bacteria such as fermenters, methanogens, acetogens, sulfate reducers, and denitrifiers. Methane is the dominant gaseous product of anaerobic degradation of organic matter and is released into the atmosphere, whereas the other trace gases are only intermediates, which are mostly cycled within the anoxic habitat. A significant percentage of the produced methane is oxidized by methanotrophic bacteria at anoxic-oxic interfaces such as the soil surface and the root surface of aquatic plants that serve as conduits for O2 transport into and CH4 transport out of the wetland soils. The dominant production processes in upland soils are different from those in wetland soils and include H2 production by biological N2 fixation, CO production by chemical decomposition of soil organic matter, and NO and N2O production by nitrification and denitrification. The processes responsible for CH4 production in upland soils are completely unclear, as are the OCS production processes in general. A problem for future research is the attribution of trace gas metabolic processes not only to functional groups of microorganisms but also to particular taxa. Thus, it is completely unclear how important microbial diversity is for the control of trace gas flux at the ecosystem level. However, different microbial communities may be part of the reason for differences in trace gas metabolism, e.g., effects of nitrogen fertilizers on CH4 uptake by soil; decrease of CH4 production with decreasing temperature; or different rates and modes of NO and N2O production in different soils and under different conditions.
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Affiliation(s)
- R Conrad
- Max-Planck-Institut für terrestrische Mikrobiologie, Marburg, Germany
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28
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Fujiwara T, Fukumori Y. Cytochrome cb-type nitric oxide reductase with cytochrome c oxidase activity from Paracoccus denitrificans ATCC 35512. J Bacteriol 1996; 178:1866-71. [PMID: 8606159 PMCID: PMC177880 DOI: 10.1128/jb.178.7.1866-1871.1996] [Citation(s) in RCA: 99] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
A highly active nitric oxide reductase was purified from Paracoccus denitrificans ATCC 35512, formerly named Thiosphaera pantotropha, which was anaerobically cultivated in the presence of nitrate. The enzyme was composed of two subunits with molecular masses of 34 and 15 kDa and contained two hemes b and one heme c per molecule. Copper was not found in the enzyme. The spectral properties suggested that one of the two hemes b and heme c were in six-coordinated low-spin states and another heme b was in a five-coordinated high-spin state and reacted with carbon monoxide. The enzyme showed high cytochrome c-nitric oxide oxidoreductase activity and formed nitrous oxide from nitric oxide with the expected stoichiometry when P. denitrificans ATCC 35512 ferrocytochrome c-550 was used as the electron donor. The V max and Km values for nitric oxide were 84 micromol of nitric oxide per min/mg of protein and 0.25 microM, respectively. Furthermore, the enzyme showed ferrocytochrome c-550-O2 oxidoreductase activity with a V max of 8.4 micromol of O2 per min/mg of protein and a Km value of 0.9 mM. Both activities were 50% inhibited by about 0.3 mM KCN.
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Affiliation(s)
- T Fujiwara
- Department of Life Science, Faculty of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama, Japan
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29
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30
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Berks BC, Ferguson SJ, Moir JW, Richardson DJ. Enzymes and associated electron transport systems that catalyse the respiratory reduction of nitrogen oxides and oxyanions. BIOCHIMICA ET BIOPHYSICA ACTA 1995; 1232:97-173. [PMID: 8534676 DOI: 10.1016/0005-2728(95)00092-5] [Citation(s) in RCA: 390] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- B C Berks
- Centre for Metalloprotein Spectroscopy and Biology, School of Biological Sciences, University of East Anglia, Norwich, UK
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31
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Arts PA, Robertson LA, Gijs Kuenen J. Nitrification and denitrification by Thiosphaera pantotropha in aerobic chemostat cultures. FEMS Microbiol Ecol 1995. [DOI: 10.1111/j.1574-6941.1995.tb00187.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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Richardson DJ, Ferguson SJ. Competition between hydrogen peroxide and nitrate for electrons from the respiratory chains ofThiosphaera pantotrophaandRhodobacter capsulatus. FEMS Microbiol Lett 1995. [DOI: 10.1111/j.1574-6968.1995.tb07821.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Moir JWB, Richardson DJ, Ferguson SJ. The expression of redox proteins of denitrification inThiosphaera pantotropha grown with oxygen, nitrate, and nitrous oxide as electron acceptors. Arch Microbiol 1995. [DOI: 10.1007/bf02568733] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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34
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Dalsgaard T, Zwart JD, Robertson LA, Kuenen J, Revsbech NP. Nitrification, denitrification and growth in artificial Thiosphaera pantotropha biofilms as measured with a combined microsensor for oxygen and nitrous oxide. FEMS Microbiol Ecol 1995. [DOI: 10.1111/j.1574-6941.1995.tb00137.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Ye RW, Haas D, Ka JO, Krishnapillai V, Zimmermann A, Baird C, Tiedje JM. Anaerobic activation of the entire denitrification pathway in Pseudomonas aeruginosa requires Anr, an analog of Fnr. J Bacteriol 1995; 177:3606-9. [PMID: 7768875 PMCID: PMC177071 DOI: 10.1128/jb.177.12.3606-3609.1995] [Citation(s) in RCA: 125] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The Pseudomonas aeruginosa gene anr, which encodes a structural and functional analog of the anaerobic regulator Fnr in Escherichia coli, was mapped to the SpeI fragment R, which is at about 59 min on the genomic map of P. aeruginosa PAO1. Wild-type P. aeruginosa PAO1 grew under anaerobic conditions with nitrate, nitrite, and nitrous oxide as alternative electron acceptors. An anr deletion mutant, PAO6261, was constructed. It was unable to grow with these alternative electron acceptors; however, its ability to denitrify was restored upon the introduction of the wild-type anr gene. In addition, the activities of two enzymes in the denitrification pathway, nitrite reductase and nitric oxide reductase, were not detectable under oxygen-limiting conditions in strain PAO6261 but were restored when complemented with the anr+ gene. These results indicate that the anr gene product plays a key role in anaerobically activating the entire denitrification pathway.
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Affiliation(s)
- R W Ye
- Department of Microbiology, Michigan State University, East Lansing 48824, USA
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Wu Q, Knowles R, Niven DF. Effect of ionophores on denitrification inFlexibacter canadensis. Can J Microbiol 1995. [DOI: 10.1139/m95-031] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Denitrification by Flexibacter canadensis was investigated by measuring the production and (or) consumption of nitrite, nitric oxide (NO), and nitrous oxide (N2O) under anaerobic conditions. Carbonyl cyanide m-chlorophenylhydrazone (CCCP), carbonyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP), 2,4-dinitrophenol, and nigericin, but not valinomycin-K+inhibited the production of nitrite and N2O from nitrate by intact cells. However, CCCP, FCCP, 2,4-dinitrophenol, nigericin, and valinomycin-K+did not affect nitrite production from nitrate by cell-free extracts. These results suggest that nitrate transport was dependent on the transmembrane pH gradient but not on the membrane potential. CCCP, FCCP, and nigericin but not 2,4-dinitrophenol and valinomycin-K+caused NO accumulation during the reduction of nitrite, and also inhibited NO consumption and N2O production from nitrite by intact cells. These results preclude an explanation for NO accumulation based on the collapse of the proton motive force by ionophores, and imply that CCCP, FCCP, and nigericin perhaps dissociated a nitrite reductase–nitric oxide reductase complex, and (or) inhibited nitric oxide reductase specifically. 2,4-Dinitrophenol and CCCP did not inhibit the reduction of N2O to dinitrogen. Addition of ≤ 1.16 μM dissolved NO did not affect the production of nitrite from nitrate, or the disappearance of nitrite or N2O. The rate of NO consumption was linear with concentrations of dissolved NO up to 67 nM. Above 67 nM NO, NO consumption was inhibited, suggesting that NO is toxic to nitric oxide reductase.Key words: ionophores, denitrification, nitric oxide, Flexibacter canadensis.
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Abstract
Reactive oxygen intermediates modulate skeletal muscle contraction, but little is known about the role of nitric oxide (NO). Here we show that rat skeletal muscle expresses neuronal-type NO synthase and that activity varies among several respiratory and limb muscles. Immunohistochemistry showed prominent staining of type II (fast) fibre cell membranes with antibodies against neuronal-type NO synthase. NO synthase activity in muscles correlated with type II fibre density. Resting diaphragm muscle produced detectable NO chi, but no reactive oxygen intermediates. In contrast, actively contracting muscle generated increased levels of reactive oxygen intermediates. Contractile function was augmented by blockers of NO synthase, extracellular NO chelation, and guanylyl cyclase inhibition; it was depressed by NO donors and by increased levels of cyclic GMP. Force-frequency plots of different muscles showed an inverse correlation between NO synthase activity and force development. Our results support two physiological functions of NO in skeletal muscle. The first is to promote relaxation through the cGMP pathway. The second is to modulate increases in contraction that are dependent on reactive oxygen intermediates and which are thought to occur through reactions with regulatory thiols on the sarcoplasmic reticulum.
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Affiliation(s)
- L Kobzik
- Department of Pathology, Brigham and Women's Hospital, Boston Massachusetts 02115
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Ye RW, Averill BA, Tiedje JM. Denitrification: production and consumption of nitric oxide. Appl Environ Microbiol 1994; 60:1053-8. [PMID: 8017903 PMCID: PMC201439 DOI: 10.1128/aem.60.4.1053-1058.1994] [Citation(s) in RCA: 162] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Affiliation(s)
- R W Ye
- Department of Microbiology, Michigan State University, East Lansing 48824
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Berks BC, Richardson DJ, Robinson C, Reilly A, Aplin RT, Ferguson SJ. Purification and characterization of the periplasmic nitrate reductase from Thiosphaera pantotropha. EUROPEAN JOURNAL OF BIOCHEMISTRY 1994; 220:117-24. [PMID: 8119278 DOI: 10.1111/j.1432-1033.1994.tb18605.x] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The periplasmic nitrate reductase of Thiosphaera pantotropha has been purified from a mutant strain (M-6) that overproduces the enzyme activity under anaerobic growth conditions. The enzyme is a complex of a 93-kDa polypeptide and a 16-kDa nitrate-oxidizable cytochrome c552. The complex contains molybdenum; a fluorescent compound with spectral features of a pterin derivative can be extracted. In contrast to the dissimilatory membrane-bound nitrate reductases, the periplasmic nitrate reductase shows high specificity for nitrate as a substrate and is insensitive to inhibition by azide. The 93-kDa subunit exhibits immunological cross-reactivity with the catalytic subunit of Rhodobacter capsulatus N22DNAR+ periplasmic nitrate reductase. Mass spectrometric comparisons of holo-cytochrome c552 and apo-cytochrome c552 demonstrated that the polypeptide bound two haem groups. Mediated redox potentiometry of the cytochrome indicated that the haem groups have reduction potentials (pH = 7.0) of approximately -15 mV and + 80 mV. The functional significance of these potentials is discussed in relation to the proposed physiological role of the enzyme as a redox valve.
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Affiliation(s)
- B C Berks
- Department of Biochemistry, University of Oxford, England
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Abstract
Denitrification in bacteria comprises a series of four reduction reactions; for nitrate, nitrite, nitric oxide and nitrous oxide. Nitrogen gas is the final product. The nature of the enzymes catalysing these reactions is described along with the the properties of the underlying electron transport systems. The factors influencing the expression of the reductases for the four reactions are reviewed along with the effect of oxygen on the activities of the enzymes of denitrification. The main emphasis is on observations made with Paracoccus denitrificans and Pseudomonas stutzeri.
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Affiliation(s)
- S J Ferguson
- Department of Biochemistry, University of Oxford, UK
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Affiliation(s)
- W G Zumft
- Lehrstuhl für Mikrobiologie, Universität Karlsruhe, Germany
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Thomsen JK, L�nsmann Iversen J, Cox RP. Interactions between respiration and denitrification during growth ofThiosphaera pantotrophain continuous culture. FEMS Microbiol Lett 1993. [DOI: 10.1111/j.1574-6968.1993.tb06342.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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Anaerobic expression of nitric oxide reductase from denitrifying Pseudomonas stutzeri. Arch Microbiol 1993. [DOI: 10.1007/bf00288586] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Zennaro E, Ciabatti I, Cutruzzola F, D'Alessandro R, Silvestrini MC. The nitrite reductase gene of Pseudomonas aeruginosa: Effect of growth conditions on the expression and construction of a mutant by gene disruption. FEMS Microbiol Lett 1993. [DOI: 10.1111/j.1574-6968.1993.tb06175.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Berks BC, Baratta D, Richardson J, Ferguson SJ. Purification and characterization of a nitrous oxide reductase from Thiosphaera pantotropha. Implications for the mechanism of aerobic nitrous oxide reduction. EUROPEAN JOURNAL OF BIOCHEMISTRY 1993; 212:467-76. [PMID: 8383047 DOI: 10.1111/j.1432-1033.1993.tb17683.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The aerobic denitrifer Thiosphaera pantotropha is able to reduce simultaneously nitrous oxide and oxygen even after anaerobic growth [Bell, L. C. & Ferguson, S. J. (1991) Biochem J. 273, 423-427]. A nitrous oxide reductase was purified from anaerobically grown T. pantotropha cells. It is argued, on the basis of inhibitor sensitivities and from immunological evidence, that the same nitrous oxide reductase is involved in nitrous oxide reduction in aerobically grown cells. The purified nitrous oxide reductase was shown to have molecular properties very similar to nitrous oxide reductases previously isolated from anaerobically denitrifying bacteria. The visible absorption spectra of the T. pantotropha enzyme resemble those of the oxygen-affected form of nitrous oxide reductases from other organisms. It is thus concluded that the T. pantotropha nitrous oxide reductase is not peculiarly resistant to the structural changes caused by oxygen. The activity of the purified T. pantotropha nitrous oxide reductase was reconstituted in vitro using horse heart cytochrome c, T. pantotropha cytochrome c551 and T. pantotropha pseudoazurin as electron donors. It is suggested on this basis that either of the T. pantotropha electron-carrier proteins are possible physiological electron donors to T. pantotropha nitrous oxide reductase. Oxygen was shown not to inhibit the in-vitro reduction of nitrous oxide with horse heart ferrocytochrome c as electron donor to the reductase.
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Affiliation(s)
- B C Berks
- Department of Biochemistry, University of Oxford, England
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Schäfer F, Ralf C. Metabolism of nitric oxide byPseudomonas stutzeriin culture and in soil. FEMS Microbiol Lett 1993. [DOI: 10.1111/j.1574-6968.1993.tb05803.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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48
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Marschall C, Frenzel P, Cypionka H. Influence of oxygen on sulfate reduction and growth of sulfate-reducing bacteria. Arch Microbiol 1993. [DOI: 10.1007/bf00250278] [Citation(s) in RCA: 137] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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49
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Inhibition of nitrate reduction by light and oxygen in Rhodobacter sphaeroides forma sp. denitrificans. Arch Microbiol 1993. [DOI: 10.1007/bf00250276] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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50
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Dalsgaard T, Revsbech NP. Regulating factors of denitrification in trickling filter biofilms as measured with the oxygen/nitrous oxide microsensor. FEMS Microbiol Lett 1992. [DOI: 10.1111/j.1574-6968.1992.tb05771.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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