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Xu SQ, Wang X, Xu L, Wang KX, Jiang YH, Zhang FY, Hong Q, He J, Liu SJ, Qiu JG. The MocR family transcriptional regulator DnfR has multiple binding sites and regulates Dirammox gene transcription in Alcaligenes faecalis JQ135. Environ Microbiol 2023; 25:675-688. [PMID: 36527381 DOI: 10.1111/1462-2920.16318] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Accepted: 12/14/2022] [Indexed: 12/23/2022]
Abstract
Microbial ammonia oxidation is vital to the nitrogen cycle. A biological process, called Dirammox (direct ammonia oxidation, NH3 →NH2 OH→N2 ), has been recently identified in Alcaligenes ammonioxydans and Alcaligenes faecalis. However, its transcriptional regulatory mechanism has not yet been fully elucidated. The present study characterized a new MocR-like transcription factor DnfR that is involved in the Dirammox process in A. faecalis strain JQ135. The entire dnf cluster was composed of 10 genes and transcribed as five transcriptional units, that is, dnfIH, dnfR, dnfG, dnfABCDE and dnfF. DnfR activates the transcription of dnfIH, dnfG and dnfABCDE genes, and represses its own transcription. The intact 1506-bp dnfR gene was required for activation of Dirammox. Electrophoretic mobility shift assays and DNase I footprinting analyses showed that DnfR has one binding site in the dnfH-dnfR intergenic region and two binding sites in the dnfG-dnfA intergenic region. Three binding sites of DnfR shared a 6-bp repeated conserved sequence 5'-GGTCTG-N17 -GGTCTG-3' which was essential for the transcription of downstream target genes. Cysteine and glutamate act as possible effectors of DnfR to activate the transcription of transcriptional units of dnfG and dnfABCDE, respectively. This study provided new insights in the transcriptional regulation mechanism of Dirammox by DnfR in A. faecalis JQ135.
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Affiliation(s)
- Si-Qiong Xu
- Key Laboratory of Agricultural and Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
| | - Xiao Wang
- Key Laboratory of Agricultural and Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
| | - Lu Xu
- Key Laboratory of Agricultural and Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
| | - Ke-Xin Wang
- Key Laboratory of Agricultural and Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
| | - Yin-Hu Jiang
- Key Laboratory of Agricultural and Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
| | - Fu-Yin Zhang
- Key Laboratory of Agricultural and Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
| | - Qing Hong
- Key Laboratory of Agricultural and Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
| | - Jian He
- Key Laboratory of Agricultural and Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
| | - Shuang-Jiang Liu
- State Key Laboratory of Microbial Resources, and Environmental Microbiology Research Center at Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Ji-Guo Qiu
- Key Laboratory of Agricultural and Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
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Nie H, Liu X, Dang Y, Sun D. Early activated quorum sensing enhanced a nosZ-deficient strain of Pseudomonas aeruginosa for stably recovering nitrous oxide from incineration leachate in microbial electrolysis cell. BIORESOURCE TECHNOLOGY 2022; 360:127394. [PMID: 35640816 DOI: 10.1016/j.biortech.2022.127394] [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: 04/15/2022] [Revised: 05/21/2022] [Accepted: 05/26/2022] [Indexed: 06/15/2023]
Abstract
In this study, a quorum sensing (QS) signal molecule, 3-oxo-C12-HSL, was supplied into ΔnosZ Pseudomonas microbial electrolysis cell system for strengthening the N2O recovery from incineration leachate. The resistance for high nitrite loading was strongly improved with nitrite removal efficiency of 80.35% compared to 67.07% from the control on day 13 due to the increasing biomass through early activated QS. Higher N2O proportion in biogas (85.85% on average) was achieved in the QS early activated reactor, which indicated the better potential for N2O recovery. Bacterial community analysis showed the purity of ΔnosZ strain with the abundance of 100% in the anode chamber at the end of the operation. This was plausibly related to the increased synthesis of phenazine derivatives by the early activated QS system. These results show a more promising way for N2O recovery by a single engineering bacteria from the high nitrogen contained actual wastewater.
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Affiliation(s)
- Hanbing Nie
- Beijing Key Laboratory for Source Control Technology of Water Pollution, Engineering Research Center for Water Pollution Source Control and Eco-remediation, College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China
| | - Xinying Liu
- Beijing Key Laboratory for Source Control Technology of Water Pollution, Engineering Research Center for Water Pollution Source Control and Eco-remediation, College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China
| | - Yan Dang
- Beijing Key Laboratory for Source Control Technology of Water Pollution, Engineering Research Center for Water Pollution Source Control and Eco-remediation, College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China
| | - Dezhi Sun
- Beijing Key Laboratory for Source Control Technology of Water Pollution, Engineering Research Center for Water Pollution Source Control and Eco-remediation, College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China.
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Genetic Foundations of Direct Ammonia Oxidation (Dirammox) to N 2 and MocR-like Transcriptional Regulator DnfR in Alcaligenes faecalis JQ135. Appl Environ Microbiol 2022; 88:e0226121. [PMID: 35108103 DOI: 10.1128/aem.02261-21] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Ammonia oxidation is an important process of both the natural nitrogen cycle and nitrogen removal from engineered ecosystems. Recently, a new ammonia oxidation pathway termed Dirammox (direct ammonia oxidation, NH3→NH2OH→N2) has been identified in Alcaligenes ammonioxydans. However, whether Dirammox is present in other microbes and its genetic regulation remains unknown. In this study, it was found that the metabolically versatile bacterium Alcaligenes faecalis strain JQ135 could efficiently convert ammonia into N2 via NH2OH under aerobic conditions. Genetic deletion and complementation results suggest that dnfABC is responsible for the ammonia oxidation to N2 in this strain. Strain JQ135 also employs aerobic denitrification, mainly producing N2O and trace amounts of N2 with nitrite as sole nitrogen source. Deletion of genes nirK and nosZ that are essential for denitrification did not impair the capability of JQ135 to oxidize ammonia to N2 (i.e., Dirammox is independent of denitrification). Furthermore, it was also demonstrated that pod (which encodes pyruvic oxime dioxygenase) was not involved in Dirammox and AFA_16745 (which was previously annotated as ammonia monooxygenase and is widespread in heterotrophic bacteria) was not an ammonia monooxygenase. The MocR-family transcriptional regulator DnfR was characterized as an activator of the dnfABC operon with the binding motif 5'-TGGTCTGT-3' in the promotor region. Bioinformatic survey showed that homologs to dnf genes are widely distributed in heterotrophic bacteria. In conclusion, this work demonstrates that besides A. ammonioxydans, Dirammox also occurs in other bacteria, and is regulated by the MocR-family transcriptional regulator DnfR. Importance Microbial ammonia oxidation is a key and rate-limiting step of the nitrogen cycle. Three previous known ammonia oxidation pathways (i.e., nitrification, anaerobic ammonia oxidation (Anammox), and complete ammonia oxidation (Comammox)) are mediated by autotrophic microbes. However, the genetic foundations of ammonia oxidation by heterotrophic microorganisms have not been investigated in depth. Recently, a previously unknown pathway, termed direct ammonia oxidation to N2 (Dirammox), has been identified in the heterotrophic bacterium Alcaligenes ammonioxydans HO-1. This paper shows that in the metabolically versatile bacterium Alcaligenes faecalis JQ135, the Dirammox pathway is mediated by dnf genes, which are independent of the denitrification pathway. Bioinformatic survey suggests that homologs to dnf genes are widely distributed in bacteria. These findings enhance the understanding of the molecular mechanisms of heterotrophic ammonia oxidation to N2.
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Peng MW, Qi J, Yan P, Guan Y, Liu YY, Sun ZH, Zhang LJ, Weng X, Shen Y, Fang F, Guo JS, Chen YP. Insight into the structure and metabolic function of iron-rich nanoparticles in anammox bacteria. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 806:150879. [PMID: 34627893 DOI: 10.1016/j.scitotenv.2021.150879] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 10/03/2021] [Accepted: 10/04/2021] [Indexed: 06/13/2023]
Abstract
Anaerobic ammonium-oxidizing (anammox) bacteria are iron abundant and depend heavily on iron-binding proteins. The iron demand of anammox bacteria is relatively large. However, it still remains some doubts where these large quantities of available iron come from and how they are regulated in anammox bacteria. Herein, iron-rich nanoparticles in anammoxosomes were detected by synchrotron soft X-ray tomography coupled with scanning transmission X-ray microscopy (STXM). The iron-rich nanoparticles were identified as ferric oxide (α-Fe2O3) mineral cores, and the local atomic structure of iron-rich nanoparticles was obtained by X-ray absorption fine-structure (XAFS) spectra. The bacterioferritin of Q1Q315 and Q1Q5F8 were detected by proteomics analysis. On this basis, the metabolic pathway centered on iron-rich nanoparticles was proposed.
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Affiliation(s)
- Meng-Wen Peng
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environments of MOE, Chongqing University, Chongqing 400045, China; China Three Gorges Corporation, Beijing 100038, China
| | - Jing Qi
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environments of MOE, Chongqing University, Chongqing 400045, China
| | - Peng Yan
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environments of MOE, Chongqing University, Chongqing 400045, China
| | - Yong Guan
- National Synchrotron Radiation Laboratory, University of Science & Technology of China, Hefei 230026, China
| | - Ying-Ying Liu
- Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Zhi-Hu Sun
- National Synchrotron Radiation Laboratory, University of Science & Technology of China, Hefei 230026, China
| | - Li-Juan Zhang
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
| | - Xun Weng
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environments of MOE, Chongqing University, Chongqing 400045, China
| | - Yu Shen
- National Base of International Science and Technology Cooperation for Intelligent Manufacturing Service, Chongqing Technology and Business University, Chongqing 400067, China
| | - Fang Fang
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environments of MOE, Chongqing University, Chongqing 400045, China
| | - Jin-Song Guo
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environments of MOE, Chongqing University, Chongqing 400045, China
| | - You-Peng Chen
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environments of MOE, Chongqing University, Chongqing 400045, China.
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An Q, Deng S, Xu J, Nan H, Li Z, Song JL. Simultaneous reduction of nitrate and Cr(VI) by Pseudomonas aeruginosa strain G12 in wastewater. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2020; 191:110001. [PMID: 31812281 DOI: 10.1016/j.ecoenv.2019.110001] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Revised: 11/20/2019] [Accepted: 11/23/2019] [Indexed: 06/10/2023]
Abstract
The interference of toxic heavy metals in the process of microbial aerobic denitrification is a hot issue in industry wastewater treatment in recent years. In this study, a multifunctional aerobic denitrifying bacterium - Pseudomonas aeruginosa G12 isolated from sewage sludge was used to explore the simultaneous removal ability to NO3--N and Cr(VI) in wastewater by a series of batch experiments. The results showed that G12 could effectively remove NO3--N (500 mg L-1) and Cr(VI) (10 mg L-1) by 98% and 93%, respectively. Meanwhile, the study found that the strain G12 had the potential to adapt to the complex external environment, including different carbon resources, nitrogen sources, and the coexisting heavy metals (Mn2+ and Cu2+). The strain G12 also had the considerable tolerance to initial NO3--N (100-700 mg L-1) and Cr(VI) (1-20 mg L-1) concentrations. The instrument analysis methods-Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD), from the molecular level, further confirmed that the strain G12 could remove NO3--N by aerobic denitrification, and the reduced functional groups (amino group, amide group, hydroxyl group and carboxyl group) on the surface of bacteria could transform Cr(VI) to Cr(III) (mainly CrCl3). This study will offer a promising new microbial resource for nitrogen and Cr(VI) removal in industry wastewater treatment.
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Affiliation(s)
- Qiang An
- College of Environment and Ecology, Chongqing University, Chongqing, 400045, PR China; The Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Chongqing University, Chongqing, 400045, PR China.
| | - Shuman Deng
- College of Environment and Ecology, Chongqing University, Chongqing, 400045, PR China
| | - Jia Xu
- College of Environment and Ecology, Chongqing University, Chongqing, 400045, PR China
| | - Hongyan Nan
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, 2002405, PR China
| | - Zheng Li
- College of Environment and Ecology, Chongqing University, Chongqing, 400045, PR China
| | - Jia-Li Song
- College of Environment and Ecology, Chongqing University, Chongqing, 400045, PR China
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Rajta A, Bhatia R, Setia H, Pathania P. Role of heterotrophic aerobic denitrifying bacteria in nitrate removal from wastewater. J Appl Microbiol 2019; 128:1261-1278. [PMID: 31587489 DOI: 10.1111/jam.14476] [Citation(s) in RCA: 74] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Revised: 09/30/2019] [Accepted: 10/01/2019] [Indexed: 11/27/2022]
Abstract
With the increase in industrial and agricultural activities, a large amount of nitrogenous compounds are released into the environment, leading to nitrate pollution. The perilous effects of nitrate present in the environment pose a major threat to human and animal health. Bioremediation provides a cost-effective and environmental friendly method to deal with this problem. The process of aerobic denitrification can reduce nitrate compounds to harmless dinitrogen gas. This review provides a brief view of the exhaustive role played by aerobic denitrifiers for tackling nitrate pollution under different ecological niches and their dependency on various environmental parameters. It also provides an understanding of the enzymes involved in aerobic denitrification. The role of aerobic denitrification to solve the issues faced by the conventional method (aerobic nitrification-anaerobic denitrification) in treating nitrogen-polluted wastewaters is elaborated.
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Affiliation(s)
- A Rajta
- Department of Biotechnology, University Institute of Engineering and Technology, Panjab University, Chandigarh, India
| | - R Bhatia
- Department of Biotechnology, University Institute of Engineering and Technology, Panjab University, Chandigarh, India
| | - H Setia
- Department of Biotechnology, University Institute of Engineering and Technology, Panjab University, Chandigarh, India
| | - P Pathania
- Department of Biotechnology, University Institute of Engineering and Technology, Panjab University, Chandigarh, India
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Smits LP, Kootte RS, Levin E, Prodan A, Fuentes S, Zoetendal EG, Wang Z, Levison BS, Cleophas MCP, Kemper EM, Dallinga-Thie GM, Groen AK, Joosten LAB, Netea MG, Stroes ESG, de Vos WM, Hazen SL, Nieuwdorp M. Effect of Vegan Fecal Microbiota Transplantation on Carnitine- and Choline-Derived Trimethylamine-N-Oxide Production and Vascular Inflammation in Patients With Metabolic Syndrome. J Am Heart Assoc 2018; 7:e008342. [PMID: 29581220 PMCID: PMC5907601 DOI: 10.1161/jaha.117.008342] [Citation(s) in RCA: 141] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Accepted: 02/16/2018] [Indexed: 12/24/2022]
Abstract
BACKGROUND Intestinal microbiota have been found to be linked to cardiovascular disease via conversion of the dietary compounds choline and carnitine to the atherogenic metabolite TMAO (trimethylamine-N-oxide). Specifically, a vegan diet was associated with decreased plasma TMAO levels and nearly absent TMAO production on carnitine challenge. METHODS AND RESULTS We performed a double-blind randomized controlled pilot study in which 20 male metabolic syndrome patients were randomized to single lean vegan-donor or autologous fecal microbiota transplantation. At baseline and 2 weeks thereafter, we determined the ability to produce TMAO from d6-choline and d3-carnitine (eg, labeled and unlabeled TMAO in plasma and 24-hour urine after oral ingestion of 250 mg of both isotope-labeled precursor nutrients), and fecal samples were collected for analysis of microbiota composition. 18F-fluorodeoxyglucose positron emission tomography/computed tomography scans of the abdominal aorta, as well as ex vivo peripheral blood mononuclear cell cytokine production assays, were performed. At baseline, fecal microbiota composition differed significantly between vegans and metabolic syndrome patients. With vegan-donor fecal microbiota transplantation, intestinal microbiota composition in metabolic syndrome patients, as monitored by global fecal microbial community structure, changed toward a vegan profile in some of the patients; however, no functional effects from vegan-donor fecal microbiota transplantation were seen on TMAO production, abdominal aortic 18F-fluorodeoxyglucose uptake, or ex vivo cytokine production from peripheral blood mononuclear cells. CONCLUSIONS Single lean vegan-donor fecal microbiota transplantation in metabolic syndrome patients resulted in detectable changes in intestinal microbiota composition but failed to elicit changes in TMAO production capacity or parameters related to vascular inflammation. CLINICAL TRIAL REGISTRATION URL: http://www.trialregister.nl. Unique identifier: NTR 4338.
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Affiliation(s)
- Loek P Smits
- Department of Vascular Medicine, Academic Medical Center, University of Amsterdam, The Netherlands
| | - Ruud S Kootte
- Department of Vascular Medicine, Academic Medical Center, University of Amsterdam, The Netherlands
| | - Evgeni Levin
- Department of Vascular Medicine, Academic Medical Center, University of Amsterdam, The Netherlands
| | - Andrei Prodan
- Department of Vascular Medicine, Academic Medical Center, University of Amsterdam, The Netherlands
| | - Susana Fuentes
- Laboratory of Microbiology, Wageningen University and Research Center, Wageningen, The Netherlands
| | - Erwin G Zoetendal
- Laboratory of Microbiology, Wageningen University and Research Center, Wageningen, The Netherlands
| | - Zeneng Wang
- Department of Cellular and Molecular Medicine, Lerner Research Institute Cleveland Clinic, Cleveland, OH
| | - Bruce S Levison
- Department of Cellular and Molecular Medicine, Lerner Research Institute Cleveland Clinic, Cleveland, OH
- Department of Pediatrics, College of Medicine and Life Sciences, University of Toledo, OH
| | - Maartje C P Cleophas
- Department of Internal Medicine and Radboud Center for Infectious Diseases (RCI), Radboud University Medical Center, Nijmegen, The Netherlands
| | - E Marleen Kemper
- Department of Clinical Pharmacy, Academic Medical Center, University of Amsterdam, The Netherlands
| | - Geesje M Dallinga-Thie
- Department of Vascular Medicine, Academic Medical Center, University of Amsterdam, The Netherlands
| | - Albert K Groen
- Department of Vascular Medicine, Academic Medical Center, University of Amsterdam, The Netherlands
| | - Leo A B Joosten
- Department of Internal Medicine and Radboud Center for Infectious Diseases (RCI), Radboud University Medical Center, Nijmegen, The Netherlands
| | - Mihai G Netea
- Department of Internal Medicine and Radboud Center for Infectious Diseases (RCI), Radboud University Medical Center, Nijmegen, The Netherlands
| | - Erik S G Stroes
- Department of Vascular Medicine, Academic Medical Center, University of Amsterdam, The Netherlands
| | - Willem M de Vos
- Laboratory of Microbiology, Wageningen University and Research Center, Wageningen, The Netherlands
- Immunobiology Research Program, Department of Bacteriology and Immunology, University of Helsinki, Finland
| | - Stanley L Hazen
- Department of Cellular and Molecular Medicine, Lerner Research Institute Cleveland Clinic, Cleveland, OH
| | - Max Nieuwdorp
- Department of Vascular Medicine, Academic Medical Center, University of Amsterdam, The Netherlands
- Department of Internal Medicine, VUMC Free University, Amsterdam, The Netherlands
- Wallenberg Laboratory, Sahlgrenska Hospital, University of Gothenburg, Sweden
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