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Sennett LB, Roco CA, Lim NYN, Yavitt JB, Dörsch P, Bakken LR, Shapleigh JP, Frostegård Å. Determining how oxygen legacy affects trajectories of soil denitrifier community dynamics and N 2O emissions. Nat Commun 2024; 15:7298. [PMID: 39181870 PMCID: PMC11344836 DOI: 10.1038/s41467-024-51688-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2024] [Accepted: 08/15/2024] [Indexed: 08/27/2024] Open
Abstract
Denitrification - a key process in the global nitrogen cycle and main source of the greenhouse gas N2O - is intricately controlled by O2. While the transition from aerobic respiration to denitrification is well-studied, our understanding of denitrifier communities' responses to cyclic oxic/anoxic shifts, prevalent in natural and engineered systems, is limited. Here, agricultural soil is exposed to repeated cycles of long or short anoxic spells (LA; SA) or constant oxic conditions (Ox). Surprisingly, denitrification and N2O reduction rates are three times greater in Ox than in LA and SA during a final anoxic incubation, despite comparable bacterial biomass and denitrification gene abundances. Metatranscriptomics indicate that LA favors canonical denitrifiers carrying nosZ clade I. Ox instead favors nosZ clade II-carrying partial- or non-denitrifiers, suggesting efficient partnering of the reduction steps among organisms. SA has the slowest denitrification progression and highest accumulation of intermediates, indicating less functional coordination. The findings demonstrate how adaptations of denitrifier communities to varying O2 conditions are tightly linked to the duration of anoxic episodes, emphasizing the importance of knowing an environment's O2 legacy for accurately predicting N2O emissions originating from denitrification.
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Affiliation(s)
- Louise B Sennett
- Faculty of Chemistry, Biotechnology, and Food Sciences, Norwegian University of Life Sciences, Norwegian University of Life Sciences, Ås, Norway.
| | - Constance A Roco
- Faculty of Chemistry, Biotechnology, and Food Sciences, Norwegian University of Life Sciences, Norwegian University of Life Sciences, Ås, Norway
- Department of Microbiology, Cornell University, Ithaca, NY, USA
| | - Natalie Y N Lim
- Faculty of Chemistry, Biotechnology, and Food Sciences, Norwegian University of Life Sciences, Norwegian University of Life Sciences, Ås, Norway
| | - Joseph B Yavitt
- Department of Natural Resources, Cornell University, Ithaca, NY, USA
| | - Peter Dörsch
- Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, Norwegian University of Life Sciences, Ås, Norway
| | - Lars R Bakken
- Faculty of Chemistry, Biotechnology, and Food Sciences, Norwegian University of Life Sciences, Norwegian University of Life Sciences, Ås, Norway
| | | | - Åsa Frostegård
- Faculty of Chemistry, Biotechnology, and Food Sciences, Norwegian University of Life Sciences, Norwegian University of Life Sciences, Ås, Norway.
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2
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Roothans N, Gabriëls M, Abeel T, Pabst M, van Loosdrecht MCM, Laureni M. Aerobic denitrification as an N2O source from microbial communities. THE ISME JOURNAL 2024; 18:wrae116. [PMID: 38913498 PMCID: PMC11272060 DOI: 10.1093/ismejo/wrae116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Revised: 04/26/2024] [Accepted: 06/21/2024] [Indexed: 06/26/2024]
Abstract
Nitrous oxide (N2O) is a potent greenhouse gas of primarily microbial origin. Oxic and anoxic emissions are commonly ascribed to autotrophic nitrification and heterotrophic denitrification, respectively. Beyond this established dichotomy, we quantitatively show that heterotrophic denitrification can significantly contribute to aerobic nitrogen turnover and N2O emissions in complex microbiomes exposed to frequent oxic/anoxic transitions. Two planktonic, nitrification-inhibited enrichment cultures were established under continuous organic carbon and nitrate feeding, and cyclic oxygen availability. Over a third of the influent organic substrate was respired with nitrate as electron acceptor at high oxygen concentrations (>6.5 mg/L). N2O accounted for up to one-quarter of the nitrate reduced under oxic conditions. The enriched microorganisms maintained a constitutive abundance of denitrifying enzymes due to the oxic/anoxic frequencies exceeding their protein turnover-a common scenario in natural and engineered ecosystems. The aerobic denitrification rates are ascribed primarily to the residual activity of anaerobically synthesised enzymes. From an ecological perspective, the selection of organisms capable of sustaining significant denitrifying activity during aeration shows their competitive advantage over other heterotrophs under varying oxygen availabilities. Ultimately, we propose that the contribution of heterotrophic denitrification to aerobic nitrogen turnover and N2O emissions is currently underestimated in dynamic environments.
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Affiliation(s)
- Nina Roothans
- Department of Biotechnology, Delft University of Technology, van der Maasweg 9, 2629 HZ Delft, the Netherlands
| | - Minke Gabriëls
- Department of Biotechnology, Delft University of Technology, van der Maasweg 9, 2629 HZ Delft, the Netherlands
| | - Thomas Abeel
- Delft Bioinformatics Lab, Delft University of Technology, van Mourik Broekmanweg 6, Delft 2628 XE, the Netherlands
- Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, 415 Main Street, Cambridge, MA 02142, United States
| | - Martin Pabst
- Department of Biotechnology, Delft University of Technology, van der Maasweg 9, 2629 HZ Delft, the Netherlands
| | - Mark C M van Loosdrecht
- Department of Biotechnology, Delft University of Technology, van der Maasweg 9, 2629 HZ Delft, the Netherlands
| | - Michele Laureni
- Department of Biotechnology, Delft University of Technology, van der Maasweg 9, 2629 HZ Delft, the Netherlands
- Department of Water Management, Delft University of Technology, Stevinweg 1, 2628 CN Delft, the Netherlands
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3
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Garrido-Amador P, Stortenbeker N, Wessels HJCT, Speth DR, Garcia-Heredia I, Kartal B. Enrichment and characterization of a nitric oxide-reducing microbial community in a continuous bioreactor. Nat Microbiol 2023; 8:1574-1586. [PMID: 37429908 PMCID: PMC10390337 DOI: 10.1038/s41564-023-01425-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 06/14/2023] [Indexed: 07/12/2023]
Abstract
Nitric oxide (NO) is a highly reactive and climate-active molecule and a key intermediate in the microbial nitrogen cycle. Despite its role in the evolution of denitrification and aerobic respiration, high redox potential and capacity to sustain microbial growth, our understanding of NO-reducing microorganisms remains limited due to the absence of NO-reducing microbial cultures obtained directly from the environment using NO as a substrate. Here, using a continuous bioreactor and a constant supply of NO as the sole electron acceptor, we enriched and characterized a microbial community dominated by two previously unknown microorganisms that grow at nanomolar NO concentrations and survive high amounts (>6 µM) of this toxic gas, reducing it to N2 with little to non-detectable production of the greenhouse gas nitrous oxide. These results provide insight into the physiology of NO-reducing microorganisms, which have pivotal roles in the control of climate-active gases, waste removal, and evolution of nitrate and oxygen respiration.
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Affiliation(s)
| | | | - Hans J C T Wessels
- Translational Metabolic Laboratory, Department of Laboratory Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Daan R Speth
- Max Planck Institute for Marine Microbiology, Bremen, Germany
| | | | - Boran Kartal
- Max Planck Institute for Marine Microbiology, Bremen, Germany.
- School of Science, Constructor University, Bremen, Germany.
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4
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Wang Z, Vishwanathan N, Kowaliczko S, Ishii S. Clarifying Microbial Nitrous Oxide Reduction under Aerobic Conditions: Tolerant, Intolerant, and Sensitive. Microbiol Spectr 2023; 11:e0470922. [PMID: 36926990 PMCID: PMC10100939 DOI: 10.1128/spectrum.04709-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Accepted: 02/18/2023] [Indexed: 03/17/2023] Open
Abstract
One of the major challenges for the bioremediation application of microbial nitrous oxide (N2O) reduction is its oxygen sensitivity. While a few strains were reported capable of reducing N2O under aerobic conditions, the N2O reduction kinetics of phylogenetically diverse N2O reducers are not well understood. Here, we analyzed and compared the kinetics of clade I and clade II N2O-reducing bacteria in the presence or absence of oxygen (O2) by using a whole-cell assay with N2O and O2 microsensors. Among the seven strains tested, N2O reduction of Stutzerimonas stutzeri TR2 and ZoBell was not inhibited by oxygen (i.e., oxygen tolerant). Paracoccus denitrificans, Azospirillum brasilense, and Gemmatimonas aurantiaca reduced N2O in the presence of O2 but slower than in the absence of O2 (i.e., oxygen sensitive). N2O reduction of Pseudomonas aeruginosa and Dechloromonas aromatica did not occur when O2 was present (i.e., oxygen intolerant). Amino acid sequences and predicted structures of NosZ were highly similar among these strains, whereas oxygen-tolerant N2O reducers had higher oxygen consumption rates. The results suggest that the mechanism of O2 tolerance is not directly related to NosZ structure but is rather related to the scavenging of O2 in the cells and/or accessory proteins encoded by the nos cluster. IMPORTANCE Some bacteria can reduce N2O in the presence of O2, whereas others cannot. It is unclear whether this trait of aerobic N2O reduction is related to the phylogeny and structure of N2O reductase. The understanding of aerobic N2O reduction is critical for guiding emission control, due to the common concurrence of N2O and O2 in natural and engineered systems. This study provided the N2O reduction kinetics of various bacteria under aerobic and anaerobic conditions and classified the bacteria into oxygen-tolerant, -sensitive, and -intolerant N2O reducers. Oxygen-tolerant N2O reducers rapidly consumed O2, which could help maintain the low O2 concentration in the cells and keep their N2O reductase active. These findings are important and useful when selecting N2O reducers for bioremediation applications.
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Affiliation(s)
- Zhiyue Wang
- Department of Civil and Environmental Engineering, University of Hawai'i, Honolulu, Hawai'i, USA
- Water Resources Research Center, University of Hawai'i, Honolulu, Hawai'i, USA
| | - Nisha Vishwanathan
- BioTechnology Institute, University of Minnesota, St. Paul, Minnesota, USA
| | - Sophie Kowaliczko
- BioTechnology Institute, University of Minnesota, St. Paul, Minnesota, USA
| | - Satoshi Ishii
- BioTechnology Institute, University of Minnesota, St. Paul, Minnesota, USA
- Department of Soil, Water, and Climate, University of Minnesota, St. Paul, Minnesota, USA
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5
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Yang R, Yuan L, Wang R. Enzymatic regulation of N 2O production by denitrifying bacteria in the sludge of biological nitrogen removal process. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 846:157513. [PMID: 35872196 DOI: 10.1016/j.scitotenv.2022.157513] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 07/14/2022] [Accepted: 07/16/2022] [Indexed: 06/15/2023]
Abstract
This study analyzed the activities of all denitrifying enzymes involved in the denitrification process under different organic loads in a continuously operating sequencing batch reactor (SBR), to reveal how the denitrifying enzymes performed while the denitrifying bacteria facing changes in organic load, and leading to nitrous oxide (N2O) production by fine-tuning enzyme activities. Results show that the activities of nitrate reductase (Nar), nitrite reductase (Nir), nitric oxide reductase (Nor) and nitrous oxide reductase (N2OR) increased with the increase of organic loads, and the increase of the activity of different enzymes promoted by the organic load increase were as Nar > Nir > Nor > N2OR. Compared with the Nar and Nir, the catalytic processes of the Nor and N2OR were more susceptible to the influence of the substrate concentration and the content of internal and external carbon sources. The Nor usually maintained "excess" catalytic activity to ensure the smooth reduction of nitric oxide when the electron donor and substrate were sufficient. Otherwise, it reduced to a relatively lower catalytic activity and remained stable. The activities of the N2OR were generally weaker than that of other denitrifying enzymes. More N2O was produced in the period feeding with low organic loads (COD/NO3--N ≤ 4.9). The mechanism of the enzyme activities (Nor and N2OR) regulating the total concentrations of N2O was clarified. When the organic load was relatively low (COD/NO3--N ≤ 2.5), the N2OR activity was inhibited due to its inability to acquire enough electrons, resulting the production of N2O. When the organic load was moderate (2.5 < COD/NO3--N ≤ 4.9), the N2OR activity was lower than the Nor activity due to the different activation rates of Nor and N2OR by the substrate in bacteria, resulting the production of N2O.
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Affiliation(s)
- Rui Yang
- School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, No.13 Yanta road, Xi'an 710055, PR China; Key Lab of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, No.13 Yanta road, Xi'an 710055, PR China; Shaanxi Key Lab of Environmental Engineering, Xi'an 710055, PR China
| | - Linjiang Yuan
- School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, No.13 Yanta road, Xi'an 710055, PR China; Key Lab of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, No.13 Yanta road, Xi'an 710055, PR China; Shaanxi Key Lab of Environmental Engineering, Xi'an 710055, PR China.
| | - Ru Wang
- School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, No.13 Yanta road, Xi'an 710055, PR China; Key Lab of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, No.13 Yanta road, Xi'an 710055, PR China; Shaanxi Key Lab of Environmental Engineering, Xi'an 710055, PR China
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6
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Read-Daily B, Ben Maamar S, Sabba F, Green S, Nerenberg R. Effect of nitrous oxide (N 2O) on the structure and function of nitrogen-oxide reducing microbial communities. CHEMOSPHERE 2022; 307:135819. [PMID: 35977570 DOI: 10.1016/j.chemosphere.2022.135819] [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: 05/13/2022] [Revised: 07/18/2022] [Accepted: 07/20/2022] [Indexed: 06/15/2023]
Abstract
Nitrous oxide (N2O) is a potent greenhouse gas that can be produced by nitrifying and denitrifying bacteria. Yet the effects of N2O on microbial communities is not well understood. We used batch tests to explore the effects of N2O on mixed denitrifying communities. Batch tests were carried out with acetate as the electron donor and with the following electron acceptors: nitrate (NO3-), nitrite (NO2-), N2O, NO3- + N2O, and NO2- + N2O. Activated sludge from a municipal wastewater treatment plant was used as the inoculum. The bacteria grew readily with N2O as the sole acceptor. When N2O was provided along with NO3- or NO2-, it was used concurrently and resulted in higher growth rates than the same acceptors without added N2O. The microbial communities resulting from N2O addition were significantly different at the genus level from those with just NO3- or NO2-. Tests with N2O as the sole added acceptor revealed a reduced diversity. Analysis of inferred gene content using PICRUSt2 indicated a greater abundance of genera with a complete denitrification pathway when growing on N2O or NO2-, relative to all other tests. This suggests that specific N2O reduction rates are high, and that N2O alone selects for a low-diversity, fully denitrifying community. When N2O is present with NO2- or NO3-, the microbial communities were more diverse and did not select exclusively for full denitrifiers. N2O alone appears to select for a "generalist" community with full denitrification pathways and lower diversity. In terms of denitrification genes, the combination of acceptors with N2O appeared to increase the number of microbes carrying nirK, while fully denitrifying bacteria appear more likely to carry nirS. Lastly, all the taxa in NO2- and N2O samples were predicted to harbor nosZ. This suggests the potential for reduced N2O emissions in denitrifying systems.
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Affiliation(s)
- B Read-Daily
- Department of Engineering and Physics, Elizabethtown College, Elizabethtown, PA, 17022, USA; Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - S Ben Maamar
- Samuel J. Wood Library, Weill Cornell Medicine, New York, NY, 10065, USA
| | - F Sabba
- Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, IN, 46556, USA; Black & Veatch, KS, USA
| | - S Green
- Rush Medical College, Chicago, IL, 60612, USA
| | - R Nerenberg
- Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, IN, 46556, USA.
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7
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Stuchiner ER, von Fischer JC. Using isotope pool dilution to understand how organic carbon additions affect N 2 O consumption in diverse soils. GLOBAL CHANGE BIOLOGY 2022; 28:4163-4179. [PMID: 35377524 PMCID: PMC9321687 DOI: 10.1111/gcb.16190] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/09/2021] [Revised: 02/24/2022] [Accepted: 03/24/2022] [Indexed: 06/14/2023]
Abstract
Nitrous oxide (N2 O) is a formidable greenhouse gas with a warming potential ~300× greater than CO2 . However, its emissions to the atmosphere have gone largely unchecked because the microbial and environmental controls governing N2 O emissions have proven difficult to manage. The microbial process N2 O consumption is the only know biotic pathway to remove N2 O from soil pores and therefore reduce N2 O emissions. Consequently, manipulating soils to increase N2 O consumption by organic carbon (OC) additions has steadily gained interest. However, the response of N2 O emissions to different OC additions are inconsistent, and it is unclear if lower N2 O emissions are due to increased consumption, decreased production, or both. Simplified and systematic studies are needed to evaluate the efficacy of different OC additions on N2 O consumption. We aimed to manipulate N2 O consumption by amending soils with OC compounds (succinate, acetate, propionate) more directly available to denitrifiers. We hypothesized that N2 O consumption is OC-limited and predicted these denitrifier-targeted additions would lead to enhanced N2 O consumption and increased nosZ gene abundance. We incubated diverse soils in the laboratory and performed a 15 N2 O isotope pool dilution assay to disentangle microbial N2 O emissions from consumption using laser-based spectroscopy. We found that amending soils with OC increased gross N2 O consumption in six of eight soils tested. Furthermore, three of eight soils showed Increased N2 O Consumption and Decreased N2 O Emissions (ICDE), a phenomenon we introduce in this study as an N2 O management ideal. All three ICDE soils had low soil OC content, suggesting ICDE is a response to relaxed C-limitation wherein C additions promote soil anoxia, consequently stimulating the reduction of N2 O via denitrification. We suggest, generally, OC additions to low OC soils will reduce N2 O emissions via ICDE. Future studies should prioritize methodical assessment of different, specific, OC-additions to determine which additions show ICDE in different soils.
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Affiliation(s)
- Emily R. Stuchiner
- Graduate Degree Program in EcologyColorado State UniversityFort CollinsColoradoUSA
- Department of BiologyColorado State UniversityFort CollinsColoradoUSA
| | - Joseph C. von Fischer
- Graduate Degree Program in EcologyColorado State UniversityFort CollinsColoradoUSA
- Department of BiologyColorado State UniversityFort CollinsColoradoUSA
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8
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Sagar I, Nimonkar Y, Dhotre D, Shouche Y, Ranade D, Dewala S, Prakash O. A Microcosm Model for the Study of Microbial Community Shift and Carbon Emission from Landfills. Indian J Microbiol 2022; 62:195-203. [DOI: 10.1007/s12088-021-00995-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Accepted: 12/07/2021] [Indexed: 12/22/2022] Open
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9
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Yang R, Yuan LJ, Wang R, Wang G, Zhu M. Role of nitrite reductase in N2O production under aerobic conditions: An index for predicting the intensity of N2O production. Biochem Eng J 2022. [DOI: 10.1016/j.bej.2021.108242] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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10
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Zhou Y, Suenaga T, Qi C, Riya S, Hosomi M, Terada A. Temperature and oxygen level determine N 2 O respiration activities of heterotrophic N 2 O-reducing bacteria: Biokinetic study. Biotechnol Bioeng 2020; 118:1330-1341. [PMID: 33305820 DOI: 10.1002/bit.27654] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 11/23/2020] [Accepted: 12/09/2020] [Indexed: 12/24/2022]
Abstract
Nitrous oxide (N2 O), a potent greenhouse gas, is reduced to N2 gas by N2 O-reducing bacteria (N2 ORB), a process which represents an N2 O sink in natural and engineered ecosystems. The N2 O sink activity by N2 ORB depends on temperature and O2 exposure, yet the specifics are not yet understood. This study explores the effects of temperature and oxygen exposure on biokinetics of pure culture N2 ORB. Four N2 ORB, representing either clade I type nosZ (Pseudomonas stutzeri JCM5965 and Paracoccus denitrificans NBRC102528) or clade II type nosZ (Azospira sp. strains I09 and I13), were individually tested. The higher activation energy for N2 O by Azospira sp. strain I13 (114.0 ± 22.6 kJ mol-1 ) compared with the other tested N2 ORB (38.3-60.1 kJ mol-1 ) indicates that N2 ORB can adapt to different temperatures. The O2 inhibition constants (KI ) of Azospira sp. strain I09 and Ps. stutzeri JCM5965 increased from 0.06 ± 0.05 and 0.05 ± 0.02 μmol L-1 to 0.92 ± 0.24 and 0.84 ± 0.31 μmol L-1 , respectively, as the temperature increased from 15°C to 35°C, while that of Azospira sp. strain I13 was temperature-independent (p = 0.106). Within the range of temperatures examined, Azospira sp. strain I13 had a faster recovery after O2 exposure compared with Azospira sp. strain I09 and Ps. stutzeri JCM5965 (p < 0.05). These results suggest that temperature and O2 exposure result in the growth of ecophysiologically distinct N2 ORB as N2 O sinks. This knowledge can help develop a suitable N2 O mitigation strategy according to the physiologies of the predominant N2 ORB.
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Affiliation(s)
- Yiwen Zhou
- Department of Chemical Engineering, Tokyo University of Agriculture and Technology, Tokyo, Japan
| | - Toshikazu Suenaga
- Department of Chemical Engineering, Tokyo University of Agriculture and Technology, Tokyo, Japan
| | - Chuang Qi
- Department of Chemical Engineering, Tokyo University of Agriculture and Technology, Tokyo, Japan.,School of Environment, Nanjing Normal University, Nanjing, China
| | - Shohei Riya
- Department of Chemical Engineering, Tokyo University of Agriculture and Technology, Tokyo, Japan
| | - Masaaki Hosomi
- Department of Chemical Engineering, Tokyo University of Agriculture and Technology, Tokyo, Japan
| | - Akihiko Terada
- Department of Chemical Engineering, Tokyo University of Agriculture and Technology, Tokyo, Japan.,Global Innovation Research Institute, Tokyo University of Agriculture and Technology, Tokyo, Japan
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Park HJ, Kwon JH, Yun J, Cho KS. Characterization of nitrous oxide reduction by Azospira sp. HJ23 isolated from advanced wastewater treatment sludge. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART A, TOXIC/HAZARDOUS SUBSTANCES & ENVIRONMENTAL ENGINEERING 2020; 55:1459-1467. [PMID: 32960129 DOI: 10.1080/10934529.2020.1812321] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 07/23/2020] [Accepted: 07/28/2020] [Indexed: 06/11/2023]
Abstract
A new nitrous oxide (N2O)-reducing bacterium was isolated from a consortium that was enriched using advanced wastewater treatment sludge as an inoculum and N2O as the sole nitrogen source. The isolated facultative anaerobe was identified as Azospira sp. HJ23. Azospira sp. HJ23 exhibited optimum N2O-reducing activity with a C/N ratio of 62 at pH 6 in the temperature range of 37 °C to 40 °C. The optimum carbon source for N2O reduction was a mixture of glucose and acetate. The maximum rate of N2O reduction by Azospira sp. HJ23 was 4.8 mmol·g-dry cell-1·h-1, and its N2O-reducing activity was higher than other known N2O reducers. Azospira sp. HJ23 possessed several functional genes for denitrification. These included narG (NO3- reductase), nirK (NO2- reductase), norB (NO reductase), and nosZ (N2O reductase) genes. These results suggest that Azospira sp. HJ23 can be applied in the denitrification process to minimalize N2O emission.
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Affiliation(s)
| | | | | | - Kyung-Suk Cho
- Department of Environmental Science and Engineering, Ewha Womans University, Seoul, Republic of Korea
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12
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Involvement of the cbb3-Type Terminal Oxidase in Growth Competition of Bacteria, Biofilm Formation, and in Switching between Denitrification and Aerobic Respiration. Microorganisms 2020; 8:microorganisms8081230. [PMID: 32806683 PMCID: PMC7464135 DOI: 10.3390/microorganisms8081230] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 08/10/2020] [Accepted: 08/10/2020] [Indexed: 11/16/2022] Open
Abstract
Paracoccus denitrificans has a branched electron transport chain with three terminal oxidases transferring electrons to molecular oxygen, namely aa3-type and cbb3-type cytochrome c oxidases and ba3-type ubiquinol oxidase. In the present study, we focused on strains expressing only one of these enzymes. The competition experiments showed that possession of cbb3-type oxidase confers significant fitness advantage during oxygen-limited growth and supports the biofilm lifestyle. The aa3-type oxidase was shown to allow rapid aerobic growth at a high oxygen supply. Activity of the denitrification pathway that had been expressed in cells grown anaerobically with nitrate was fully inhibitable by oxygen only in wild-type and cbb3 strains, while in strains aa3 and ba3 dinitrogen production from nitrate and oxygen consumption occurred simultaneously. Together, the results highlight the importance of the cbb3-type oxidase for the denitrification phenotype and suggest a way of obtaining novel bacterial strains capable of aerobic denitrification.
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13
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Vasilaki V, Massara TM, Stanchev P, Fatone F, Katsou E. A decade of nitrous oxide (N 2O) monitoring in full-scale wastewater treatment processes: A critical review. WATER RESEARCH 2019; 161:392-412. [PMID: 31226538 DOI: 10.1016/j.watres.2019.04.022] [Citation(s) in RCA: 88] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 04/09/2019] [Accepted: 04/10/2019] [Indexed: 06/09/2023]
Abstract
Direct nitrous oxide (N2O) emissions during the biological nitrogen removal (BNR) processes can significantly increase the carbon footprint of wastewater treatment plant (WWTP) operations. Recent onsite measurement of N2O emissions at WWTPs have been used as an alternative to the controversial theoretical methods for the N2O calculation. The full-scale N2O monitoring campaigns help to expand our knowledge on the N2O production pathways and the triggering operational conditions of processes. The accurate N2O monitoring could help to find better process control solutions to mitigate N2O emissions of wastewater treatment systems. However, quantifying the emissions and understanding the long-term behaviour of N2O fluxes in WWTPs remains challenging and costly. A review of the recent full-scale N2O monitoring campaigns is conducted. The analysis covers the quantification and mitigation of emissions for different process groups, focusing on techniques that have been applied for the identification of dominant N2O pathways and triggering operational conditions, techniques using operational data and N2O data to identify mitigation measures and mechanistic modelling. The analysis of various studies showed that there are still difficulties in the comparison of N2O emissions and the development of emission factor (EF) databases; the N2O fluxes reported in literature vary significantly even among groups of similar processes. The results indicated that the duration of the monitoring campaigns can impact the EF range. Most N2O monitoring campaigns lasting less than one month, have reported N2O EFs less than 0.3% of the N-load, whereas studies lasting over a year have a median EF equal to 1.7% of the N-load. The findings of the current study indicate that complex feature extraction and multivariate data mining methods can efficiently convert wastewater operational and N2O data into information, determine complex relationships within the available datasets and boost the long-term understanding of the N2O fluxes behaviour. The acquisition of reliable full-scale N2O monitoring data is significant for the calibration and validation of the mechanistic models -describing the N2O emission generation in WWTPs. They can be combined with the multivariate tools to further enhance the interpretation of the complicated full-scale N2O emission patterns. Finally, a gap between the identification of effective N2O mitigation strategies and their actual implementation within the monitoring and control of WWTPs has been identified. This study concludes that there is a further need for i) long-term N2O monitoring studies, ii) development of data-driven methodological approaches for the analysis of WWTP operational and N2O data, and iii) better understanding of the trade-offs among N2O emissions, energy consumption and system performance to support the optimization of the WWTPs operation.
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Affiliation(s)
- V Vasilaki
- Department of Civil & Environmental Engineering, Brunel University London, Uxbridge Campus, Middlesex, UB8 3PH, Uxbridge, UK
| | - T M Massara
- Institute of Environment, Health and Societies, Brunel University London, Uxbridge Campus, Middlesex, UB8 3PH, Uxbridge, UK
| | - P Stanchev
- Department of Civil & Environmental Engineering, Brunel University London, Uxbridge Campus, Middlesex, UB8 3PH, Uxbridge, UK
| | - F Fatone
- Department of Science and Engineering of Materials, Environment and City Planning, Faculty of Engineering, Polytechnic University of Marche, Ancona, Italy
| | - E Katsou
- Department of Civil & Environmental Engineering, Brunel University London, Uxbridge Campus, Middlesex, UB8 3PH, Uxbridge, UK; Institute of Environment, Health and Societies, Brunel University London, Uxbridge Campus, Middlesex, UB8 3PH, Uxbridge, UK.
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14
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Ren Y, Ngo HH, Guo W, Ni BJ, Liu Y. Linking the nitrous oxide production and mitigation with the microbial community in wastewater treatment: A review. ACTA ACUST UNITED AC 2019. [DOI: 10.1016/j.biteb.2019.100191] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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15
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Sabba F, Terada A, Wells G, Smets BF, Nerenberg R. Nitrous oxide emissions from biofilm processes for wastewater treatment. Appl Microbiol Biotechnol 2018; 102:9815-9829. [DOI: 10.1007/s00253-018-9332-7] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Revised: 08/13/2018] [Accepted: 08/15/2018] [Indexed: 01/21/2023]
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