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Wang L, Li A. Impact of zero-valent iron on nitrifying granular sludge for 17α-ethinylestradiol removal and its mechanism. CHEMOSPHERE 2023; 333:138904. [PMID: 37182710 DOI: 10.1016/j.chemosphere.2023.138904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2023] [Revised: 04/13/2023] [Accepted: 05/08/2023] [Indexed: 05/16/2023]
Abstract
Aerobic granulation of nitrifying activated sludge could enhance the removal of 17α-ethinylestradiol (EE2) via abiotic nitration induced by reactive nitrogen species, cometabolism by ammonia-oxidizing bacteria and biodegradation by heterotrophic bacteria. Zero-valent iron (ZVI), a promising and low-cost material, has previously been applied to effectively enhance biological wastewater treatment. The impact and the effect mechanism of ZVI on nitrifying granular sludge (NGS) for EE2 removal was investigated in this study. The results showed that the addition of ZVI achieved better EE2 removal, though ZVI was not conducive to the accumulation of nitrite in NGS which reduced the abiotic transformation of EE2. Moreover, ZVI enriched heterotrophic denitrifying bacteria such as Arenimonas, thus changing the EE2 removal pathway and improving the degradation and mineralization of EE2. In addition, ZVI reduced the emission risk of the greenhouse gas N2O and strengthened the stability of the granules. Metagenomic analysis further revealed that the functional genes related to EE2 mineralization, nitrite oxidation, N2O reduction and quorum sensing in NGS were enriched with ZVI addition. This study provides meaningful guidance for ZVI application in the NGS process to achieve efficient and simultaneous removal of ammonia and emerging contaminants.
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Affiliation(s)
- Lili Wang
- Key Laboratory of Water and Sediment Sciences of Ministry of Education, State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing, 100875, China; Laboratory of Environmental Protection in Water Transport Engineering, Tianjin Research Institute of Water Transport Engineering, Tanggu, Tianjin, 300456, China
| | - Anjie Li
- Key Laboratory of Water and Sediment Sciences of Ministry of Education, State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing, 100875, China.
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2
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Chawley P, Rana A, Jagadevan S. Envisioning role of ammonia oxidizing bacteria in bioenergy production and its challenges: a review. Crit Rev Biotechnol 2021; 42:931-952. [PMID: 34641754 DOI: 10.1080/07388551.2021.1976099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Ammonia oxidizing bacteria (AOB) play a key role in the biological oxidation of ammonia to nitrite and mark their significance in the biogeochemical nitrogen cycle. There has been significant development in harnessing the ammonia oxidizing potential of AOB in the past few decades. However, very little is known about the potential applications of AOB in the bioenergy sector. As alternate sources of energy represent a thrust area for environmental sustainability, the role of AOB in bioenergy production becomes a significant area of exploration. This review highlights the role of AOB in bioenergy production and emphasizes the understanding of the genetic make-up and key cellular biochemical reactions occurring in AOB, thereby leading to the exploration of its various functional aspects. Recent outcomes in novel ammonia/nitrite oxidation steps occurring in a model AOB - Nitrosomonas europaea propel us to explore several areas of environmental implementation. Here we present the significant role of AOB in microbial fuel cells (MFC) where Nitrosomonas sp. play both anodic and cathodic functions in the generation of bioelectricity. This review also presents the potential role of AOB in curbing fuel demand by producing alternative liquid fuel such as methanol and biodiesel. Herein, the multiple roles of AOB in bioenergy production namely: bioelectricity generation, bio-methanol, and biodiesel production have been presented.
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Affiliation(s)
- Parmita Chawley
- Department of Environmental Science and Engineering, Indian Institute of Technology (Indian School of Mines), Dhanbad, Jharkhand, India
| | - Anu Rana
- Department of Environmental Science and Engineering, Indian Institute of Technology (Indian School of Mines), Dhanbad, Jharkhand, India
| | - Sheeja Jagadevan
- Department of Environmental Science and Engineering, Indian Institute of Technology (Indian School of Mines), Dhanbad, Jharkhand, India
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Corrochano-Monsalve M, González-Murua C, Bozal-Leorri A, Lezama L, Artetxe B. Mechanism of action of nitrification inhibitors based on dimethylpyrazole: A matter of chelation. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 752:141885. [PMID: 32890835 DOI: 10.1016/j.scitotenv.2020.141885] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 08/19/2020] [Accepted: 08/20/2020] [Indexed: 05/25/2023]
Abstract
In agriculture, the applied nitrogen (N) can be lost in the environment in different forms because of microbial transformations. It is of special concern the nitrate (NO3-) leaching and the nitrous oxide (N2O) emissions, due to their negative environmental impacts. Nitrification inhibitors (NIs) based on dimethylpyrazole (DMP) are applied worldwide in order to reduce N losses. These compounds delay ammonium (NH4+) oxidation by inhibiting ammonia-oxidizing bacteria (AOB) growth. However, their mechanism of action has not been demonstrated, which represent an important lack of knowledge to use them correctly. In this work, through chemical and biological analysis, we unveil the mechanism of action of the commonly applied 3,4-dimethyl-1H-pyrazole dihydrogen phosphate (DMPP) and the new DMP-based NI, 2-(3,4-dimethyl-1H-pyrazol-1-yl)-succinic acid (DMPSA). Our results show that DMP and DMPSA form complexes with copper (Cu2+) cations, an indispensable cofactor in the nitrification pathway. Three coordination compounds namely [Cu(DMP)4Cl2] (CuDMP1), [Cu(DMP)4SO4]n (CuDMP2) and [Cu(DMPSA)2]·H2O (CuDMPSA) have been synthesized and chemical and structurally characterized. The CuDMPSA complex is more stable than those containing DMP ligands; however, both NIs show the same nitrification inhibition efficiency in soils with different Cu contents, suggesting that the active specie in both cases is DMP. Our soil experiment reveals that the usual application dose is enough to inhibit nitrification within the range of Cu and Zn contents present in agricultural soils, although their effects vary depending on the content of these elements. As a result of AOB inhibition by these NIs, N2O-reducing bacteria seem to be beneficed in Cu-limited soils due to a reduction in the competence. This opens up the possibility to induce N2O reduction to N2 through Cu fertilization. On the other hand, when fertilizing with micronutrients such as Cu and Zn, the use of NIs could be beneficial to counteract the increase of nitrification derived from their application.
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Affiliation(s)
- Mario Corrochano-Monsalve
- Department of Plant Biology and Ecology, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), Leioa, Spain.
| | - Carmen González-Murua
- Department of Plant Biology and Ecology, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), Leioa, Spain
| | - Adrián Bozal-Leorri
- Department of Plant Biology and Ecology, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), Leioa, Spain
| | - Luis Lezama
- Department of Inorganic Chemistry, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), Leioa, Spain
| | - Beñat Artetxe
- Department of Inorganic Chemistry, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), Leioa, Spain
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Fujita Y, Walton M, Das G, Dohnalkova A, Vanzin G, Anderko A. Impacts of anthropogenic gadolinium on the activity of the ammonia oxidizing bacterium Nitrosomonas europaea. CHEMOSPHERE 2020; 257:127250. [PMID: 32600781 DOI: 10.1016/j.chemosphere.2020.127250] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 05/01/2020] [Accepted: 05/28/2020] [Indexed: 06/11/2023]
Abstract
Widespread use of gadolinium-based contrast agents in medical imaging has resulted in increased Gd inputs to municipal wastewater treatment plants. Others have reported that typical wastewater treatment does not attenuate Gd, resulting in discharges to natural waters. However, whether elevated Gd impacts the performance of biological treatment has not been investigated. We examined whether gadolinium chloride or Gd chelated with diethylenetriaminepentaacetic acid (DTPA) affected the activity of the model nitrifying bacterium Nitrosomonas europaea. At nominal GdCl3 additions ranging from 1 to 500 μM, no impact was observed compared to the control. Most (>98%) of the added Gd precipitated, and extracellular GdPO4 nanoparticles were observed. When chelated with DTPA, Gd remained soluble, but no statistically significant impact on ammonia oxidation was observed until the highest concentrations tested. At 300 and 500 μM Gd-DTPA, a temporary reduction of nitrite production relative to the control (effect size 1.3 mg l-1 and 1.5 mg l-1, respectively, at 24 h) was seen. By itself, DTPA was highly inhibitory. Modeling suggested that DTPA likely chelated other metals, but adjusting the concentrations of the most abundant metals in the medium, calcium and magnesium, indicated that lowering their free ion activities was probably not the cause of inhibition. Complexation of other essential metals was more likely. Our studies indicate that while the low bioavailability of Gd may limit its ecosystem impacts, the role of synthetic ligands used with Gd and other rare earth elements should be considered as the production, use and disposal of these elements increases.
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Affiliation(s)
- Yoshiko Fujita
- Idaho National Laboratory, Biological & Chemical Science & Engineering Department, Idaho Falls, ID, 83415-2203, United States.
| | - Michelle Walton
- Idaho National Laboratory, Biological & Chemical Science & Engineering Department, Idaho Falls, ID, 83415-2203, United States
| | - Gaurav Das
- OLI Systems, Inc., 240 Cedar Knolls Road, Suite 301, Cedar Knolls, NJ, 07927, United States
| | - Alice Dohnalkova
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA, 99354, United States
| | - Gary Vanzin
- Colorado School of Mines, Department of Civil & Environmental Engineering, 1012 14th Street, Golden, CO, 80401, United States
| | - Andre Anderko
- OLI Systems, Inc., 240 Cedar Knolls Road, Suite 301, Cedar Knolls, NJ, 07927, United States
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5
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Wendeborn S. Chemie, Biologie und Regulierung der Nitrifikation von Ammonium im Boden. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.201903014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Sebastian Wendeborn
- Fachhochschule Nordwestschweiz FHNWHochschule für Life SciencesInstitut für Chemie und Bioanalytik Hofackerstrasse 30 CH-4132 Muttenz Schweiz
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Wendeborn S. The Chemistry, Biology, and Modulation of Ammonium Nitrification in Soil. Angew Chem Int Ed Engl 2019; 59:2182-2202. [PMID: 31116902 DOI: 10.1002/anie.201903014] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 05/15/2019] [Indexed: 11/11/2022]
Abstract
Approximately two percent of the world's energy is consumed in the production of ammonia from hydrogen and nitrogen gas. Ammonia is used as a fertilizer ingredient for agriculture and distributed in the environment on an enormous scale to promote crop growth in intensive farming. Only 30-50 % of the nitrogen applied is assimilated by crop plants; the remaining 50-70 % goes into biological processes such as nitrification by microbial metabolism in the soil. This leads to an imbalance in the global nitrogen cycle and higher nitrous oxide emissions (a potent and significant greenhouse gas) as well as contamination of ground and surface waters by nitrate from the nitrogen-fertilized farmland. This Review gives a critical overview of the current knowledge of soil microbes involved in the chemistry of ammonia nitrification, the structures and mechanisms of the enzymes involved, and phytochemicals capable of inhibiting ammonia nitrification.
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Affiliation(s)
- Sebastian Wendeborn
- University of Applied Sciences and Arts Northwestern Switzerland, School of Life Sciences, Institute for Chemistry and Bioanalytics, Hofackerstrasse 30, CH-4132, Muttenz, Switzerland
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7
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Nsenga Kumwimba M, Meng F. Roles of ammonia-oxidizing bacteria in improving metabolism and cometabolism of trace organic chemicals in biological wastewater treatment processes: A review. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 659:419-441. [PMID: 31096373 DOI: 10.1016/j.scitotenv.2018.12.236] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2018] [Revised: 11/20/2018] [Accepted: 12/15/2018] [Indexed: 05/27/2023]
Abstract
While there has been a significant recent improvement in the removal of pollutants in natural and engineered systems, trace organic chemicals (TrOCs) are posing a major threat to aquatic environments and human health. There is a critical need for developing potential strategies that aim at enhancing metabolism and/or cometabolism of these compounds. Recently, knowledge regarding biodegradation of TrOCs by ammonia-oxidizing bacteria (AOB) has been widely developed. This review aims to delineate an up-to-date version of the ecophysiology of AOB and outline current knowledge related to biodegradation efficiencies of the frequently reported TrOCs by AOB. The paper also provides an insight into biodegradation pathways by AOB and transformation products of these compounds and makes recommendations for future research of AOB. In brief, nitrifying WWTFs (wastewater treatment facilities) were superior in degrading most TrOCs than non-nitrifying WWTFs due to cometabolic biodegradation by the AOB. To fully understand and/or enhance the cometabolic biodegradation of TrOCs by AOB, recent molecular research has focused on numerous crucial factors including availability of the compounds to AOB, presence of growth substrate (NH4-N), redox potentials, microorganism diversity (AOB and heterotrophs), physicochemical properties and operational parameters of the WWTFs, molecular structure of target TrOCs and membrane-based technologies, may all significantly impact the cometabolic biodegradation of TrOCs. Still, further exploration is required to elucidate the mechanisms involved in biodegradation of TrOCs by AOB and the toxicity levels of formed products.
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Affiliation(s)
- Mathieu Nsenga Kumwimba
- School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, PR China; Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou 510275, PR China; Faculty of Agronomy, Department of Natural Resources and Environmental Management, University of Lubumbashi, Democratic Republic of the Congo
| | - Fangang Meng
- School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, PR China; Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou 510275, PR China.
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8
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Tolar BB, Herrmann J, Bargar JR, van den Bedem H, Wakatsuki S, Francis CA. Integrated structural biology and molecular ecology of N-cycling enzymes from ammonia-oxidizing archaea. ENVIRONMENTAL MICROBIOLOGY REPORTS 2017; 9:484-491. [PMID: 28677304 DOI: 10.1111/1758-2229.12567] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2017] [Revised: 06/01/2017] [Accepted: 06/25/2017] [Indexed: 06/07/2023]
Abstract
Knowledge of the molecular ecology and environmental determinants of ammonia-oxidizing organisms is critical to understanding and predicting the global nitrogen (N) and carbon cycles, but an incomplete biochemical picture hinders in vitro studies of N-cycling enzymes. Although an integrative structural and dynamic characterization at the atomic scale would advance our understanding of function tremendously, structural knowledge of key N-cycling enzymes from ecologically relevant ammonia oxidizers is unfortunately extremely limited. Here, we discuss the challenges and opportunities for examining the ecology of ammonia-oxidizing organisms, particularly uncultivated Thaumarchaeota, through (meta)genome-driven structural biology of the enzymes ammonia monooxygenase (AMO) and nitrite reductase (NirK).
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Affiliation(s)
- Bradley B Tolar
- Department of Earth System Science, Stanford University, Stanford, CA 94305, USA
| | - Jonathan Herrmann
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
- Biosciences Division, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - John R Bargar
- Biosciences Division, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Henry van den Bedem
- Biosciences Division, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Soichi Wakatsuki
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
- Biosciences Division, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
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9
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Bennett K, Sadler NC, Wright AT, Yeager C, Hyman MR. Activity-Based Protein Profiling of Ammonia Monooxygenase in Nitrosomonas europaea. Appl Environ Microbiol 2016; 82:2270-2279. [PMID: 26826234 PMCID: PMC4959501 DOI: 10.1128/aem.03556-15] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2015] [Accepted: 01/27/2016] [Indexed: 11/20/2022] Open
Abstract
Nitrosomonas europaea is an aerobic nitrifying bacterium that oxidizes ammonia (NH3) to nitrite (NO2 (-)) through the sequential activities of ammonia monooxygenase (AMO) and hydroxylamine dehydrogenase (HAO). Many alkynes are mechanism-based inactivators of AMO, and here we describe an activity-based protein profiling method for this enzyme using 1,7-octadiyne (17OD) as a probe. Inactivation of NH4 (+)-dependent O2 uptake by N. europaea by 17OD was time- and concentration-dependent. The effects of 17OD were specific for ammonia-oxidizing activity, andde novoprotein synthesis was required to reestablish this activity after cells were exposed to 17OD. Cells were reacted with Alexa Fluor 647 azide using a copper-catalyzed azide-alkyne cycloaddition (CuAAC) (click) reaction, solubilized, and analyzed by SDS-PAGE and infrared (IR) scanning. A fluorescent 28-kDa polypeptide was observed for cells previously exposed to 17OD but not for cells treated with either allylthiourea or acetylene prior to exposure to 17OD or for cells not previously exposed to 17OD. The fluorescent polypeptide was membrane associated and aggregated when heated with β-mercaptoethanol and SDS. The fluorescent polypeptide was also detected in cells pretreated with other diynes, but not in cells pretreated with structural homologs containing a single ethynyl functional group. The membrane fraction from 17OD-treated cells was conjugated with biotin-azide and solubilized in SDS. Streptavidin affinity-purified polypeptides were on-bead trypsin-digested, and amino acid sequences of the peptide fragments were determined by liquid chromatography-mass spectrometry (LC-MS) analysis. Peptide fragments from AmoA were the predominant peptides detected in 17OD-treated samples. In-gel digestion and matrix-assisted laser desorption ionization-tandem time of flight (MALDI-TOF/TOF) analyses also confirmed that the fluorescent 28-kDa polypeptide was AmoA.
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Affiliation(s)
- Kristen Bennett
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina, USA
| | - Natalie C Sadler
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Aaron T Wright
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Chris Yeager
- Biosciences Division, Los Alamos National Laboratory, Los Alamos, New Mexico, USA
| | - Michael R Hyman
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina, USA
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10
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Solomon EI, Heppner DE, Johnston EM, Ginsbach JW, Cirera J, Qayyum M, Kieber-Emmons MT, Kjaergaard CH, Hadt RG, Tian L. Copper active sites in biology. Chem Rev 2014; 114:3659-853. [PMID: 24588098 PMCID: PMC4040215 DOI: 10.1021/cr400327t] [Citation(s) in RCA: 1138] [Impact Index Per Article: 113.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
| | - David E. Heppner
- Department of Chemistry, Stanford University, Stanford, CA, 94305
| | | | - Jake W. Ginsbach
- Department of Chemistry, Stanford University, Stanford, CA, 94305
| | - Jordi Cirera
- Department of Chemistry, Stanford University, Stanford, CA, 94305
| | - Munzarin Qayyum
- Department of Chemistry, Stanford University, Stanford, CA, 94305
| | | | | | - Ryan G. Hadt
- Department of Chemistry, Stanford University, Stanford, CA, 94305
| | - Li Tian
- Department of Chemistry, Stanford University, Stanford, CA, 94305
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11
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Tran NH, Urase T, Ngo HH, Hu J, Ong SL. Insight into metabolic and cometabolic activities of autotrophic and heterotrophic microorganisms in the biodegradation of emerging trace organic contaminants. BIORESOURCE TECHNOLOGY 2013; 146:721-731. [PMID: 23948223 DOI: 10.1016/j.biortech.2013.07.083] [Citation(s) in RCA: 240] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2013] [Revised: 07/17/2013] [Accepted: 07/19/2013] [Indexed: 05/06/2023]
Abstract
Many efforts have been made to understand the biodegradation of emerging trace organic contaminants (EOCs) in the natural and engineered systems. This review summarizes the current knowledge on the biodegradation of EOCs while having in-depth discussion on metabolism and cometabolism of EOCs. Biodegradation of EOCs is mainly attributed to cometabolic activities of both heterotrophic and autotrophic microorganisms. Metabolism of EOCs can only be observed by heterotrophic microbes. Autotrophic ammonia oxidizing bacteria (AOB) and ammonia oxidizing archaeal (AOA) cometabolize a variety of EOCs via the non-specific enzymes, such as ammonia monooxygenase (AMO). Higher biodegradation of EOCs is often noted under nitrification at high ammonia loading rate. The presence of a growth substrate promotes cometabolic biodegradation of EOCs. Potential strategies for enhancing the biodegradation of EOCs were also proposed in this review.
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Affiliation(s)
- Ngoc Han Tran
- Department of Civil and Environmental Engineering, Faculty of Engineering, National University of Singapore, 1 Engineering Drive 2, Singapore 117576, Singapore.
| | - Taro Urase
- School of Bioscience and Biotechnology, Tokyo University of Technology, Katakura 1404-1, Hachioji, Tokyo 1920982, Japan
| | - Huu Hao Ngo
- School of Civil and Environmental Engineering, University of Technology Sydney, PO Box 123, Broadway, NSW 2007, Australia.
| | - Jiangyong Hu
- Department of Civil and Environmental Engineering, Faculty of Engineering, National University of Singapore, 1 Engineering Drive 2, Singapore 117576, Singapore
| | - Say Leong Ong
- Department of Civil and Environmental Engineering, Faculty of Engineering, National University of Singapore, 1 Engineering Drive 2, Singapore 117576, Singapore
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12
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yingling B, zhengfang Y. Application of an integrated statistical design for optimization of culture condition for ammonium removal by Nitrosomonas europaea. PLoS One 2013; 8:e60322. [PMID: 23565225 PMCID: PMC3614901 DOI: 10.1371/journal.pone.0060322] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Accepted: 02/25/2013] [Indexed: 11/19/2022] Open
Abstract
Statistical methodology was applied to the optimization of the ammonium oxidation by Nitrosomonas europaea for biomass concentration (CB), nitrite yield (YN) and ammonium removal (RA). Initial screening by Plackett-Burman design was performed to select major variables out of nineteen factors, among which NH4Cl concentration (CN), trace element solution (TES), agitation speed (AS), and fermentation time (T) were found to have significant effects. Path of steepest ascent and response surface methodology was applied to optimize the levels of the selected factors. Finally, multi-objective optimization was used to obtain optimal condition by compromise of the three desirable objectives through a combination of weighted coefficient method coupled with entropy measurement methodology. These models enabled us to identify the optimum operation conditions (CN = 84.1 mM; TES = 0.74 ml; AS = 100 rpm and T = 78 h), under which CB = 3.386×108 cells/ml; YN = 1.98 mg/mg and RA = 97.76% were simultaneously obtained. The optimized conditions were shown to be feasible through verification tests.
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Affiliation(s)
- Bao yingling
- Department of Environmental Engineering, Peking University, The Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing, China
| | - Ye zhengfang
- Department of Environmental Engineering, Peking University, The Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing, China
- * E-mail:
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Abstract
As a trace element copper has an important role in cellular function like many other transition metals. Its ability to undergo redox changes [Cu(I) ↔ Cu(II)] makes copper an ideal cofactor in enzymes catalyzing electron transfers. However, this redox change makes copper dangerous for a cell since it is able to be involved in Fenton-like reactions creating reactive oxygen species (ROS). Cu(I) also is a strong soft metal and can attack and destroy iron-sulfur clusters thereby releasing iron which can in turn cause oxidative stress. Therefore, copper homeostasis has to be highly balanced to ensure proper cellular function while avoiding cell damage.Throughout evolution bacteria and archaea have developed a highly regulated balance in copper metabolism. While for many prokaryotes copper uptake seems to be unspecific, others have developed highly sophisticated uptake mechanisms to ensure the availability of sufficient amounts of copper. Within the cytoplasm copper is sequestered by various proteins and molecules, including specific copper chaperones, to prevent cellular damage. Copper-containing proteins are usually located in the cytoplasmic membrane with the catalytic domain facing the periplasm, in the periplasm of Gram-negative bacteria, or they are secreted, limiting the necessity of copper to accumulate in the cytoplasm. To prevent cellular damage due to excess copper, bacteria and archaea have developed various copper detoxification strategies. In this chapter we attempt to give an overview of the mechanisms employed by bacteria and archaea to handle copper and the importance of the metal for cellular function as well as in the global nutrient cycle.
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Affiliation(s)
- Christopher Rensing
- Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1870, Frederiksberg C, Denmark
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