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Ye F, Wang Y, Duan L, Wu W, Huang Y, Wang J, Chen Y, Zhao Z. Nitrous oxide (N 2O) emissions at the air-water-sediment interfaces of cascade reservoirs in the Yunnan-Guizhou Plateau: Spatial patterns and environmental controls. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 357:124436. [PMID: 38925220 DOI: 10.1016/j.envpol.2024.124436] [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: 05/03/2024] [Revised: 06/05/2024] [Accepted: 06/23/2024] [Indexed: 06/28/2024]
Abstract
The construction of cascade reservoirs can interfere with the natural hydrologic cycles of basins, causing negative environmental effects such as altering the emission patterns of the Nitrous oxide (N2O), a potent greenhouse gas. To elucidate the impact of cascade reservoirs construction on river N2O emissions, we utilized the thin boundary model and the incubation experiments to estimate the N2O fluxes at the air-water interface and at the water-sediment interface of cascade reservoirs on the Yunnan-Guizhou Plateau, respectively. Additionally, we explored the influence of various factors, with particular emphasis on damming, on N2O emissions and production. Moreover, we identified the main pathways of N2O production and proposed management strategies to mitigate N2O emissions from cascade reservoirs. The findings revealed that N2O fluxes at the air-water interface and the water-sediment interface were 4.73 ± 1.32 μmol m-2 · d-1 and 15.56 ± 1.98 μmol m-2 · d-1, respectively. Influenced by temperature, dissolved oxygen (DO), resource substances (active nitrogen substrates and dissolved organic carbon (DOC)) and reservoir properties (scale, hydraulic retention time (HRT), reservoir age, etc.), the N2O concentration and flux exhibited notable spatial heterogeneity, gradually increasing downstream. Temperature has a significant direct impact on N2O flux, as well as indirect effects through DO and resource chemicals. Furthermore, the correlation between dissolved oxygen utilization rate (AOU) and net N2O flux (ΔN2O) indicated that N2O emissions at the water-air interface were primarily attributable to nitrification, whereas those at the water-sediment interface were predominantly driven by denitrification. These findings not only enhance our comprehension of N2O emissions at various interfaces of cascade reservoirs but also offer theoretical backing for the formulation of management strategies aimed at efficiently mitigating N2O emissions from continuously dammed rivers.
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Affiliation(s)
- Fei Ye
- School of Water and Environment, Chang'an University, Xi'an, 710054, China; Key Laboratory of Subsurface Hydrology and Ecological Effects in Arid Region, Ministry of Education, Chang'an University, China
| | - Yi Wang
- School of Water and Environment, Chang'an University, Xi'an, 710054, China; Key Laboratory of Subsurface Hydrology and Ecological Effects in Arid Region, Ministry of Education, Chang'an University, China
| | - Lei Duan
- School of Water and Environment, Chang'an University, Xi'an, 710054, China; Key Laboratory of Subsurface Hydrology and Ecological Effects in Arid Region, Ministry of Education, Chang'an University, China.
| | - Wei Wu
- Xi'an University of Technology, Xi'an, 710048, China
| | - Yaqi Huang
- Xi'an University of Technology, Xi'an, 710048, China
| | - Jiawei Wang
- Xi'an University of Technology, Xi'an, 710048, China
| | - Yue Chen
- School of Water and Environment, Chang'an University, Xi'an, 710054, China; Key Laboratory of Subsurface Hydrology and Ecological Effects in Arid Region, Ministry of Education, Chang'an University, China
| | - Zhengzheng Zhao
- School of Water and Environment, Chang'an University, Xi'an, 710054, China; Key Laboratory of Subsurface Hydrology and Ecological Effects in Arid Region, Ministry of Education, Chang'an University, China
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Lourenço KS, Suleiman AKA, Pijl A, Dimitrov MR, Cantarella H, Kuramae EE. Mix-method toolbox for monitoring greenhouse gas production and microbiome responses to soil amendments. MethodsX 2024; 12:102699. [PMID: 38660030 PMCID: PMC11041840 DOI: 10.1016/j.mex.2024.102699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Accepted: 04/04/2024] [Indexed: 04/26/2024] Open
Abstract
In this study, we adopt an interdisciplinary approach, integrating agronomic field experiments with soil chemistry, molecular biology techniques, and statistics to investigate the impact of organic residue amendments, such as vinasse (a by-product of sugarcane ethanol production), on soil microbiome and greenhouse gas (GHG) production. The research investigates the effects of distinct disturbances, including organic residue application alone or combined with inorganic N fertilizer on the environment. The methods assess soil microbiome dynamics (composition and function), GHG emissions, and plant productivity. Detailed steps for field experimental setup, soil sampling, soil chemical analyses, determination of bacterial and fungal community diversity, quantification of genes related to nitrification and denitrification pathways, measurement and analysis of gas fluxes (N2O, CH4, and CO2), and determination of plant productivity are provided. The outcomes of the methods are detailed in our publications (Lourenço et al., 2018a; Lourenço et al., 2018b; Lourenço et al., 2019; Lourenço et al., 2020). Additionally, the statistical methods and scripts used for analyzing large datasets are outlined. The aim is to assist researchers by addressing common challenges in large-scale field experiments, offering practical recommendations to avoid common pitfalls, and proposing potential analyses, thereby encouraging collaboration among diverse research groups.•Interdisciplinary methods and scientific questions allow for exploring broader interconnected environmental problems.•The proposed method can serve as a model and protocol for evaluating the impact of soil amendments on soil microbiome, GHG emissions, and plant productivity, promoting more sustainable management practices.•Time-series data can offer detailed insights into specific ecosystems, particularly concerning soil microbiota (taxonomy and functions).
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Affiliation(s)
- Késia Silva Lourenço
- Microbial Ecology Department, Netherlands Institute of Ecology (NIOO), Droevendaalsesteeg 10, Wageningen 6708, PB, The Netherlands
- Soils and Environmental Resources Center, Agronomic Institute of Campinas (IAC), Av. Barão de Itapura 1481, Campinas 13020-902, SP, Brazil
| | - Afnan Khalil Ahmad Suleiman
- Microbial Ecology Department, Netherlands Institute of Ecology (NIOO), Droevendaalsesteeg 10, Wageningen 6708, PB, The Netherlands
- Soil Health group, Bioclear Earth B.V., Rozenburglaan 13, Groningen 9727 DL, The Netherlands
| | - Agata Pijl
- Microbial Ecology Department, Netherlands Institute of Ecology (NIOO), Droevendaalsesteeg 10, Wageningen 6708, PB, The Netherlands
| | - Mauricio R. Dimitrov
- Microbial Ecology Department, Netherlands Institute of Ecology (NIOO), Droevendaalsesteeg 10, Wageningen 6708, PB, The Netherlands
| | - Heitor Cantarella
- Soils and Environmental Resources Center, Agronomic Institute of Campinas (IAC), Av. Barão de Itapura 1481, Campinas 13020-902, SP, Brazil
| | - Eiko Eurya Kuramae
- Microbial Ecology Department, Netherlands Institute of Ecology (NIOO), Droevendaalsesteeg 10, Wageningen 6708, PB, The Netherlands
- Ecology and Biodiversity, Institute of Environmental Biology, Utrecht University, Utrecht, The Netherlands
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3
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Deb S, Lewicka-Szczebak D, Rohe L. Microbial nitrogen transformations tracked by natural abundance isotope studies and microbiological methods: A review. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 926:172073. [PMID: 38554959 DOI: 10.1016/j.scitotenv.2024.172073] [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: 01/03/2024] [Revised: 03/07/2024] [Accepted: 03/27/2024] [Indexed: 04/02/2024]
Abstract
Nitrogen is an essential nutrient in the environment that exists in multiple oxidation states in nature. Numerous microbial processes are involved in its transformation. Knowledge about very complex N cycling has been growing rapidly in recent years, with new information about associated isotope effects and about the microbes involved in particular processes. Furthermore, molecular methods that are able to detect and quantify particular processes are being developed, applied and combined with other analytical approaches, which opens up new opportunities to enhance understanding of nitrogen transformation pathways. This review presents a summary of the microbial nitrogen transformation, including the respective isotope effects of nitrogen and oxygen on different nitrogen-bearing compounds (including nitrates, nitrites, ammonia and nitrous oxide), and the microbiological characteristics of these processes. It is supplemented by an overview of molecular methods applied for detecting and quantifying the activity of particular enzymes involved in N transformation pathways. This summary should help in the planning and interpretation of complex research studies applying isotope analyses of different N compounds and combining microbiological and isotopic methods in tracking complex N cycling, and in the integration of these results in modelling approaches.
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Affiliation(s)
- Sushmita Deb
- Institute of Geological Sciences, University of Wrocław, pl. M. Borna 9, 50-204 Wrocław, Poland
| | | | - Lena Rohe
- Thünen Institute of Climate-Smart Agriculture, Bundesallee 65, 38116 Braunschweig, Germany
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4
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Li X, Qi M, Li Q, Wu B, Fu Y, Liang X, Yin G, Zheng Y, Dong H, Liu M, Hou L. Acidification Offset Warming-Induced Increase in N 2O Production in Estuarine and Coastal Sediments. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:4989-5002. [PMID: 38442002 DOI: 10.1021/acs.est.3c10691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/07/2024]
Abstract
Global warming and acidification, induced by a substantial increase in anthropogenic CO2 emissions, are expected to have profound impacts on biogeochemical cycles. However, underlying mechanisms of nitrous oxide (N2O) production in estuarine and coastal sediments remain rarely constrained under warming and acidification. Here, the responses of sediment N2O production pathways to warming and acidification were examined using a series of anoxic incubation experiments. Denitrification and N2O production were largely stimulated by the warming, while N2O production decreased under the acidification as well as the denitrification rate and electron transfer efficiency. Compared to warming alone, the combination of warming and acidification decreased N2O production by 26 ± 4%, which was mainly attributed to the decline of the N2O yield by fungal denitrification. Fungal denitrification was mainly responsible for N2O production under the warming condition, while bacterial denitrification predominated N2O production under the acidification condition. The reduced site preference of N2O under acidification reflects that the dominant pathways of N2O production were likely shifted from fungal to bacterial denitrification. In addition, acidification decreased the diversity and abundance of nirS-type denitrifiers, which were the keystone taxa mediating the low N2O production. Collectively, acidification can decrease sediment N2O yield through shifting the responsible production pathways, partly counteracting the warming-induced increase in N2O emissions, further reducing the positive climate warming feedback loop.
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Affiliation(s)
- Xiaofei Li
- State Key Laboratory of Estuarine and Coastal Research, Yangtze Delta Estuarine Wetland Ecosystem Observation and Research Station, Ministry of Education & Shanghai, East China Normal University, Shanghai 200241, China
- Key Laboratory of Geographic Information Science of the Ministry of Education, School of Geographic Sciences, East China Normal University, Shanghai 200241, China
| | - Mengting Qi
- Key Laboratory of Geographic Information Science of the Ministry of Education, School of Geographic Sciences, East China Normal University, Shanghai 200241, China
| | - Qiuxuan Li
- Key Laboratory of Geographic Information Science of the Ministry of Education, School of Geographic Sciences, East China Normal University, Shanghai 200241, China
| | - Boshuang Wu
- State Key Laboratory of Estuarine and Coastal Research, Yangtze Delta Estuarine Wetland Ecosystem Observation and Research Station, Ministry of Education & Shanghai, East China Normal University, Shanghai 200241, China
| | - Yuxuan Fu
- State Key Laboratory of Estuarine and Coastal Research, Yangtze Delta Estuarine Wetland Ecosystem Observation and Research Station, Ministry of Education & Shanghai, East China Normal University, Shanghai 200241, China
| | - Xia Liang
- State Key Laboratory of Estuarine and Coastal Research, Yangtze Delta Estuarine Wetland Ecosystem Observation and Research Station, Ministry of Education & Shanghai, East China Normal University, Shanghai 200241, China
| | - Guoyu Yin
- Key Laboratory of Geographic Information Science of the Ministry of Education, School of Geographic Sciences, East China Normal University, Shanghai 200241, China
| | - Yanling Zheng
- Key Laboratory of Geographic Information Science of the Ministry of Education, School of Geographic Sciences, East China Normal University, Shanghai 200241, China
| | - Hongpo Dong
- State Key Laboratory of Estuarine and Coastal Research, Yangtze Delta Estuarine Wetland Ecosystem Observation and Research Station, Ministry of Education & Shanghai, East China Normal University, Shanghai 200241, China
| | - Min Liu
- Key Laboratory of Geographic Information Science of the Ministry of Education, School of Geographic Sciences, East China Normal University, Shanghai 200241, China
| | - Lijun Hou
- State Key Laboratory of Estuarine and Coastal Research, Yangtze Delta Estuarine Wetland Ecosystem Observation and Research Station, Ministry of Education & Shanghai, East China Normal University, Shanghai 200241, China
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5
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Xu MJ, Cui YW, Huang MQ, Sui Y. Simultaneous inorganic nitrogen and phosphate removal by aerobic-heterotrophic fungus Fusarium keratoplasticum FSP1: Performance, pathway and application. BIORESOURCE TECHNOLOGY 2024; 393:130141. [PMID: 38040316 DOI: 10.1016/j.biortech.2023.130141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 11/15/2023] [Accepted: 11/28/2023] [Indexed: 12/03/2023]
Abstract
Fungi with multiple contaminant removal function have rarely been studied. Here, a novel fungal strain Fusarium keratoplasticum FSP1, which was isolated from halophilic granular sludge, is reported for first time to perform simultaneous nitrogen and phosphate removal. The strain showed wide adaptability under C/N ratios of 30-35, salinities of 0 %-3 % (m/v), and pH of 7.5-9.5. The maximum removal rates of ammonium, nitrate and nitrite were 4.43, 4.01 and 2.97 mg N/L/h. The nitrogen balance, enzyme activity and substrate conversion experiments demonstrated a single strain FSP1 can assimilate inorganic nitrogen and convert inorganic nitrogen to gaseous nitrogen through heterotrophic nitrification or aerobic denitrification. About 39 %-42 % of the degraded phosphorus was in the extracellular polymeric substances (EPS). Orthophosphate was the main phosphorus species in the cell, whereas phosphate monoester and diester were in the EPS. The novel strain FSP1 is a potential candidate for wastewater treatment.
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Affiliation(s)
- Meng-Jiao Xu
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Beijing University of Technology, Beijing 100124, China
| | - You-Wei Cui
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Beijing University of Technology, Beijing 100124, China.
| | - Mei-Qi Huang
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Beijing University of Technology, Beijing 100124, China
| | - Yuan Sui
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Beijing University of Technology, Beijing 100124, China
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6
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Chang J, Peng P, Farhan Ul-Haque M, Hira A, DiSpirito AA, Semrau JD. Inhibition of nitrous oxide reduction in forest soil microcosms by different forms of methanobactin. Environ Microbiol 2023; 25:2338-2350. [PMID: 37395163 DOI: 10.1111/1462-2920.16456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Accepted: 06/14/2023] [Indexed: 07/04/2023]
Abstract
Copper plays a critical role in controlling greenhouse gas emissions as it is a key component of the particulate methane monooxygenase and nitrous oxide reductase. Some methanotrophs excrete methanobactin (MB) that has an extremely high copper affinity. As a result, MB may limit the ability of other microbes to gather copper, thereby decreasing their activity as well as impacting microbial community composition. Here, we show using forest soil microcosms that multiple forms of MB; MB from Methylosinus trichosporium OB3b (MB-OB3b) and MB from Methylocystis sp. strain SB2 (MB-SB2) increased nitrous oxide (N2 O) production as well caused significant shifts in microbial community composition. Such effects, however, were mediated by the amount of copper in the soils, with low-copper soil microcosms showing the strongest response to MB. Furthermore, MB-SB2 had a stronger effect, likely due to its higher affinity for copper. The presence of either form of MB also inhibited nitrite reduction and generally increased the presence of genes encoding for the iron-containing nitrite reductase (nirS) over the copper-dependent nitrite reductase (nirK). These data indicate the methanotrophic-mediated production of MB can significantly impact multiple steps of denitrification, as well as have broad effects on microbial community composition of forest soils.
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Affiliation(s)
- Jin Chang
- Department of Civil and Environmental Engineering, University of Michigan, Ann Arbor, Michigan, USA
| | - Peng Peng
- Department of Civil and Environmental Engineering, University of Michigan, Ann Arbor, Michigan, USA
| | | | - Abid Hira
- School of Biological Sciences, University of the Punjab, Quaid-e-Azam Campus, Lahore, Pakistan
| | - Alan A DiSpirito
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, Iowa, USA
| | - Jeremy D Semrau
- Department of Civil and Environmental Engineering, University of Michigan, Ann Arbor, Michigan, USA
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7
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Wan Z, Wang L, Huang G, Rasul F, Awan MI, Cui H, Liu K, Yu X, Tang H, Wang S, Xu H. nirS and nosZII bacterial denitrifiers as well as fungal denitrifiers are coupled with N 2O emissions in long-term fertilized soils. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 897:165426. [PMID: 37429471 DOI: 10.1016/j.scitotenv.2023.165426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2023] [Revised: 07/07/2023] [Accepted: 07/07/2023] [Indexed: 07/12/2023]
Abstract
Fertilizer application plays a critical role in soil fertility and crop yield and has been reported to significantly affect soil denitrification. However, the mechanisms by which denitrifying bacteria (nirK, nirS, nosZI, and nosZII) and fungi (nirK and p450nor) affect soil denitrification are poorly understood. Therefore, in this study, we investigated the effect of different fertilization treatments on the abundance, community structure, and function of soil denitrifying microorganisms in an agricultural ecosystem with long-term fertilization using mineral fertilizer or manure and their combination. The results showed that the application of organic fertilizer significantly increased the abundance of nirK-, nirS-, nosZI-, and nosZII-type denitrifying bacteria as the soil pH and phosphorus content increased. However, only the community structure of nirS- and nosZII-type denitrifying bacteria was influenced by the application of organic fertilizer, which led to a higher contribution of bacteria to nitrous oxide (N2O) emissions than that observed after inorganic fertilizer application. The increase in soil pH reduced the abundance of nirK-type denitrifying fungi, which may have presented a competitive disadvantage relative to bacteria, resulting in a lower contribution of fungi to N2O emissions than that observed after inorganic fertilizer application. The results demonstrated that organic fertilization had a significant impact on the community structure and activity of soil denitrifying bacteria and fungi. Our results also highlighted that after organic fertilizer application, nirS- and nosZII-denitrifying bacteria communities represent likely hot spots of bacterial soil N2O emissions while nirK-type denitrifying fungi represent hot spots for fungal soil N2O emissions.
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Affiliation(s)
- Ziwei Wan
- Research Center on Ecological Sciences, Jiangxi Agricultural University, Nanchang 330045, China
| | - Ling Wang
- Faculty of Resources and Environmental Science, Hubei University, Wuhan 430000, China
| | - Guoqin Huang
- Research Center on Ecological Sciences, Jiangxi Agricultural University, Nanchang 330045, China
| | - Fahd Rasul
- Irrigated Agriculture Research and Extension Center, Washington State University, Washington 99350, United States
| | - Masood Iqbal Awan
- Department of Agronomy, Sub-Campus Depalpur, Okara, University of Agriculture, Faisalabad 38000, Pakistan
| | - Huanming Cui
- Research Center on Ecological Sciences, Jiangxi Agricultural University, Nanchang 330045, China
| | - Kailou Liu
- Jiangxi Institute of Red Soil and Germplasm Resources, Nanchang 331717, China
| | - Xichu Yu
- Jiangxi Institute of Red Soil and Germplasm Resources, Nanchang 331717, China
| | - Haiying Tang
- College of Agriculture and Biotechnology, Hunan University of Humanities, Science and Technology, Loudi 417000, China
| | - Shubin Wang
- Research Center on Ecological Sciences, Jiangxi Agricultural University, Nanchang 330045, China
| | - Huifang Xu
- Research Center on Ecological Sciences, Jiangxi Agricultural University, Nanchang 330045, China.
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8
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Robertson GP. Denitrification and the challenge of scaling microsite knowledge to the globe. MLIFE 2023; 2:229-238. [PMID: 38817807 PMCID: PMC10989938 DOI: 10.1002/mlf2.12080] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/05/2023] [Revised: 06/21/2023] [Accepted: 07/16/2023] [Indexed: 06/01/2024]
Abstract
Our knowledge of microbial processes-who is responsible for what, the rates at which they occur, and the substrates consumed and products produced-is imperfect for many if not most taxa, but even less is known about how microsite processes scale to the ecosystem and thence the globe. In both natural and managed environments, scaling links fundamental knowledge to application and also allows for global assessments of the importance of microbial processes. But rarely is scaling straightforward: More often than not, process rates in situ are distributed in a highly skewed fashion, under the influence of multiple interacting controls, and thus often difficult to sample, quantify, and predict. To date, quantitative models of many important processes fail to capture daily, seasonal, and annual fluxes with the precision needed to effect meaningful management outcomes. Nitrogen cycle processes are a case in point, and denitrification is a prime example. Statistical models based on machine learning can improve predictability and identify the best environmental predictors but are-by themselves-insufficient for revealing process-level knowledge gaps or predicting outcomes under novel environmental conditions. Hybrid models that incorporate well-calibrated process models as predictors for machine learning algorithms can provide both improved understanding and more reliable forecasts under environmental conditions not yet experienced. Incorporating trait-based models into such efforts promises to improve predictions and understanding still further, but much more development is needed.
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Affiliation(s)
- G. Philip Robertson
- W. K. Kellogg Biological StationMichigan State UniversityHickory CornersMichiganUSA
- Department of Plant, Soil, and Microbial SciencesMichigan State UniversityEast LansingMichiganUSA
- Great Lakes Bioenergy Research CenterMichigan State UniversityEast LansingMichiganUSA
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9
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Bösch Y, Pold G, Saghaï A, Karlsson M, Jones CM, Hallin S. Distribution and Environmental Drivers of Fungal Denitrifiers in Global Soils. Microbiol Spectr 2023; 11:e0006123. [PMID: 37222601 PMCID: PMC10269876 DOI: 10.1128/spectrum.00061-23] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Accepted: 05/05/2023] [Indexed: 05/25/2023] Open
Abstract
The microbial process of denitrification is the primary source of the greenhouse gas nitrous oxide (N2O) from terrestrial ecosystems. Fungal denitrifiers, unlike many bacteria, lack the N2O reductase, and thereby are sources of N2O. Still, their diversity, global distribution, and environmental determinants, as well as their relative importance, compared to bacterial and archaeal denitrifiers, remain unresolved. Employing a phylogenetically informed approach to analyze 1,980 global soil and rhizosphere metagenomes for the denitrification marker gene nirK, which codes for the copper dependent nitrite reductase in denitrification, we show that fungal denitrifiers are sparse, yet cosmopolitan and that they are dominated by saprotrophs and pathogens. Few showed biome-specific distribution patterns, although members of the Fusarium oxysporum species complex, which are known to produce substantial amounts of N2O, were proportionally more abundant and diverse in the rhizosphere than in other biomes. Fungal denitrifiers were most frequently detected in croplands, but they were most abundant in forest soils when normalized to metagenome size. Nevertheless, the overwhelming dominance of bacterial and archaeal denitrifiers suggests a much lower fungal contribution to N2O emissions than was previously estimated. In relative terms, they could play a role in soils that are characterized by a high carbon to nitrogen ratio and a low pH, especially in the tundra as well as in boreal and temperate coniferous forests. Because global warming predicts the proliferation of fungal pathogens, the prevalence of potential plant pathogens among fungal denitrifiers and the cosmopolitan distribution of these organisms suggest that fungal denitrifier abundance may increase in terrestrial ecosystems. IMPORTANCE Fungal denitrifiers, in contrast to their bacterial counterparts, are a poorly studied functional group within the nitrogen cycle, even though they produce the greenhouse gas N2O. To curb soil N2O emissions, a better understanding of their ecology and distribution in soils from different ecosystems is needed. Here, we probed a massive amount of DNA sequences and corresponding soil data from a large number of samples that represented the major soil environments for a broad understanding of fungal denitrifier diversity at the global scale. We show that fungal denitrifiers are predominantly cosmopolitan saprotrophs and opportunistic pathogens. Fungal denitrifiers constituted, on average, 1% of the total denitrifier community. This suggests that earlier estimations of fungal denitrifier abundance, and, thereby, it is also likely that the contributions of fungal denitrifiers to N2O emissions have been overestimated. Nevertheless, with many fungal denitrifiers being plant pathogens, they could become increasingly relevant, as soilborne pathogenic fungi are predicted to increase with ongoing climate change.
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Affiliation(s)
- Yvonne Bösch
- Swedish University of Agricultural Sciences, Department of Forest Mycology and Plant Pathology, Uppsala, Sweden
| | - Grace Pold
- Swedish University of Agricultural Sciences, Department of Forest Mycology and Plant Pathology, Uppsala, Sweden
| | - Aurélien Saghaï
- Swedish University of Agricultural Sciences, Department of Forest Mycology and Plant Pathology, Uppsala, Sweden
| | - Magnus Karlsson
- Swedish University of Agricultural Sciences, Department of Forest Mycology and Plant Pathology, Uppsala, Sweden
| | - Christopher M. Jones
- Swedish University of Agricultural Sciences, Department of Forest Mycology and Plant Pathology, Uppsala, Sweden
| | - Sara Hallin
- Swedish University of Agricultural Sciences, Department of Forest Mycology and Plant Pathology, Uppsala, Sweden
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10
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Su X, Cui L, Tang Y, Wen T, Yang K, Wang Y, Zhang J, Zhu G, Yang X, Hou L, Zhu YG. Denitrification and N 2O Emission in Estuarine Sediments in Response to Ocean Acidification: From Process to Mechanism. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:14828-14839. [PMID: 36194569 DOI: 10.1021/acs.est.2c03550] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Global estuarine ecosystems are experiencing severe nitrogen pollution and ocean acidification (OA) simultaneously. Sedimentary denitrification is an important way of reactive nitrogen removal but at the same time leads to the emission of large amounts of nitrous oxide (N2O), a potent greenhouse gas. It is known that OA in estuarine regions could impact denitrification and N2O production; however, the underlying mechanism is still underexplored. Here, sediment incubation and pure culture experiments were conducted to explore the OA impacts on microbial denitrification and the associated N2O emissions in estuarine sediments. Under neutral (in situ) conditions, fungal N2O emission dominated in the sediment, while the bacterial and fungal sources had a similar role under acidification. This indicated that acidification decreased the sedimentary fungal denitrification and likely inhibited the activity of fungal denitrifiers. To explore molecular mechanisms, a denitrifying fungal strain of Penicillium janthinellum was isolated from the sediments. By using deuterium-labeled single-cell Raman spectroscopy and isobaric tags for relative and absolute quantitation proteomics, we found that acidification inhibited electron transfers in P. janthinellum and downregulated expressions of the proteins related to energy production and conservation. Two collaborative pathways of energy generation in the P. janthinellum were further revealed, that is, aerobic oxidative phosphorylation and TCA cycle and anoxic pyruvate fermentation. This indicated a distinct energy supply strategy from bacterial denitrification. Our study provides insights into fungi-mediated nitrogen cycle in acidifying aquatic ecosystems.
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Affiliation(s)
- Xiaoxuan Su
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen361021, China
- Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment; Key Laboratory of Low-Carbon Green Agriculture in Southwestern China, Ministry of Agriculture and Rural Affairs, Southwest University, Chongqing400715, China
| | - Li Cui
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen361021, China
| | - Yijia Tang
- School of Life and Environmental Sciences, The University of Sydney, Biomedical Building (C81), Sydney, New South Wales2015, Australia
| | - Teng Wen
- School of Geography, Nanjing Normal University, Nanjing210023, China
- Key Laboratory of Virtual Geographic Environment, Ministry of Education, Nanjing Normal University, Nanjing210023, China
| | - Kai Yang
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen361021, China
| | - Yingmu Wang
- College of Civil Engineering, Fuzhou University, Fuzhou350116, China
| | - Jinbo Zhang
- School of Geography, Nanjing Normal University, Nanjing210023, China
- Key Laboratory of Virtual Geographic Environment, Ministry of Education, Nanjing Normal University, Nanjing210023, China
| | - Guibing Zhu
- State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing100085, China
| | - Xiaoru Yang
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen361021, China
| | - Lijun Hou
- State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai200062, China
| | - Yong-Guan Zhu
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen361021, China
- State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing100085, China
- University of the Chinese Academy of Sciences, Beijing100049, China
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11
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Bellido-Pedraza CM, Calatrava V, Llamas A, Fernandez E, Sanz-Luque E, Galvan A. Nitrous Oxide Emissions from Nitrite Are Highly Dependent on Nitrate Reductase in the Microalga Chlamydomonas reinhardtii. Int J Mol Sci 2022; 23:9412. [PMID: 36012676 PMCID: PMC9409008 DOI: 10.3390/ijms23169412] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 08/16/2022] [Accepted: 08/18/2022] [Indexed: 12/11/2022] Open
Abstract
Nitrous oxide (N2O) is a powerful greenhouse gas and an ozone-depleting compound whose synthesis and release have traditionally been ascribed to bacteria and fungi. Although plants and microalgae have been proposed as N2O producers in recent decades, the proteins involved in this process have been only recently unveiled. In the green microalga Chlamydomonas reinhardtii, flavodiiron proteins (FLVs) and cytochrome P450 (CYP55) are two nitric oxide (NO) reductases responsible for N2O synthesis in the chloroplast and mitochondria, respectively. However, the molecular mechanisms feeding these NO reductases are unknown. In this work, we use cavity ring-down spectroscopy to monitor N2O and CO2 in cultures of nitrite reductase mutants, which cannot grow on nitrate or nitrite and exhibit enhanced N2O emissions. We show that these mutants constitute a very useful tool to study the rates and kinetics of N2O release under different conditions and the metabolism of this greenhouse gas. Our results indicate that N2O production, which was higher in the light than in the dark, requires nitrate reductase as the major provider of NO as substrate. Finally, we show that the presence of nitrate reductase impacts CO2 emissions in both light and dark conditions, and we discuss the role of NO in the balance between CO2 fixation and release.
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Affiliation(s)
| | - Victoria Calatrava
- Department of Biochemistry and Molecular Biology, University of Cordoba, 14004 Cordoba, Spain
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305, USA
| | - Angel Llamas
- Department of Biochemistry and Molecular Biology, University of Cordoba, 14004 Cordoba, Spain
| | - Emilio Fernandez
- Department of Biochemistry and Molecular Biology, University of Cordoba, 14004 Cordoba, Spain
| | - Emanuel Sanz-Luque
- Department of Biochemistry and Molecular Biology, University of Cordoba, 14004 Cordoba, Spain
| | - Aurora Galvan
- Department of Biochemistry and Molecular Biology, University of Cordoba, 14004 Cordoba, Spain
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12
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Wei W, Isobe K, Shiratori Y, Yano M, Toyoda S, Koba K, Yoshida N, Shen H, Senoo K. Revisiting the involvement of ammonia oxidizers and denitrifiers in nitrous oxide emission from cropland soils. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 287:117494. [PMID: 34182387 DOI: 10.1016/j.envpol.2021.117494] [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: 02/05/2021] [Revised: 05/05/2021] [Accepted: 05/27/2021] [Indexed: 06/13/2023]
Abstract
Nitrous oxide (N2O), an ozone-depleting greenhouse gas, is generally produced by soil microbes, particularly NH3 oxidizers and denitrifiers, and emitted in large quantities after N fertilizer application in croplands. N2O can be produced via multiple processes, and reduced, with the involvement of more diverse microbes with different physiological constraints than previously thought; therefore, there is a lack of consensus on the production processes and microbes involved under different agricultural practices. In this study, multiple approaches were applied, including N2O isotopocule analyses, microbial gene transcript measurements, and selective inhibition assays, to revisit the involvement of NH3 oxidizers and denitrifiers, including the previously-overlooked taxa, in N2O emission from a cropland, and address the biological and environmental factors controlling the N2O production processes. Then, we synthesized the results from those approaches and revealed that the overlooked denitrifying bacteria and fungi were more involved in N2O production than the long-studied ones. We also demonstrated that the N2O production processes and soil microbes involved were different based on fertilization practices (plowing or surface application) and fertilization types (manure or urea). In particular, we identified the following intensified activities: (1) N2O production by overlooked denitrifying fungi after manure fertilization onto soil surface; (2) N2O production by overlooked denitrifying bacteria and N2O reduction by long-studied N2O-reducing bacteria after manure fertilization into the plowed layer; and (3) N2O production by NH3-oxidizing bacteria and overlooked denitrifying bacteria and fungi when urea fertilization was applied into the plowed layer. We finally propose the conceptual scheme of N flow after fertilization based on distinct physiological constraints among the diverse NH3 oxidizers and denitrifiers, which will help us understand the environmental context-dependent N2O emission processes.
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Affiliation(s)
- Wei Wei
- School of Agricultural Engineering, Jiangsu University, Jiangsu, 212013, China; Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, 113-8657, Japan
| | - Kazuo Isobe
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, 113-8657, Japan.
| | - Yutaka Shiratori
- Niigata Agricultural Research Institute, Niigata, 940-0826, Japan
| | - Midori Yano
- Center for Ecological Research, Kyoto University, Shiga, 5202113, Japan
| | - Sakae Toyoda
- School of Materials and Chemical Technology, Tokyo Institute of Technology, Yokohama, 226-8503, Japan
| | - Keisuke Koba
- Center for Ecological Research, Kyoto University, Shiga, 5202113, Japan
| | - Naohiro Yoshida
- School of Materials and Chemical Technology, Tokyo Institute of Technology, Yokohama, 226-8503, Japan; Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo, 152-8550, Japan; National Institute of Information and Communications Technology, Tokyo, 184-8795, Japan
| | - Haoyang Shen
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, 113-8657, Japan
| | - Keishi Senoo
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, 113-8657, Japan; Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo, 113-8657, Japan
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13
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Soil Redox Controls CO 2, CH 4 and N 2O Efflux from White-Rot Fungi in Temperate Forest Ecosystems. J Fungi (Basel) 2021; 7:jof7080621. [PMID: 34436159 PMCID: PMC8398011 DOI: 10.3390/jof7080621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 07/14/2021] [Accepted: 07/26/2021] [Indexed: 11/17/2022] Open
Abstract
Microaerophilic white-rot fungi (WRF) are impacted by oxygen depletion because of fluctuating redox occurrence in southern temperate forest soils of Chile (1500-5000 mm year-1). How these conditions influence WRF survival has been scarcely examined. We explored the contributions of WRF to greenhouse gas (GHG) emissions of N2O and CH4 and soil organic C oxidation (CO2) in five sterilized and inoculated forest soils derived from various parent materials and climates. The soil was incubated for 20 days following (i) oxic, (ii) anoxic, and (iii) fluctuating redox conditions. Fungi contributed to 45% of the total GHG under redox fluctuating conditions, including the contribution of bacteria, while the opposite (26%) was valid for oxic treatment. On average, the highest gas emission (62%) was N2O for WRF under redox treatment, followed by anoxic (22%) and oxic (16%) treatments, while CO2 and CH4 emissions followed oxic > redox > anoxic. These data suggest that indigenous microbial WRF communities are well adapted to fluctuating redox milieu with a significant release of GHG emissions in humid temperate forests of the southern cone.
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14
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Shan J, Sanford RA, Chee-Sanford J, Ooi SK, Löffler FE, Konstantinidis KT, Yang WH. Beyond denitrification: The role of microbial diversity in controlling nitrous oxide reduction and soil nitrous oxide emissions. GLOBAL CHANGE BIOLOGY 2021; 27:2669-2683. [PMID: 33547715 DOI: 10.1111/gcb.15545] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 01/11/2021] [Indexed: 05/02/2023]
Abstract
Many biotic and abiotic processes contribute to nitrous oxide (N2 O) production in the biosphere, but N2 O consumption in the environment has heretofore been attributed primarily to canonical denitrifying microorganisms. The nosZ genes encoding the N2 O reductase enzyme, NosZ, responsible for N2 O reduction to dinitrogen are now known to include two distinct groups: the well-studied Clade I which denitrifiers typically possess, and the novel Clade II possessed by diverse groups of microorganisms, most of which are non-denitrifiers. Clade II N2 O reducers could play an important, previously unrecognized role in controlling N2 O emissions for several reasons, including: (1) the consumption of N2 O produced by processes other than denitrification, (2) hypothesized non-respiratory functions of NosZ as an electron sink or for N2 O detoxification, (3) possible differing enzyme kinetics of Clade II NosZ compared to Clade I NosZ, and (4) greater nosZ gene abundance for Clade II compared to Clade I in soils of many ecosystems. Despite the potential ecological significance of Clade II NosZ, a census of 800 peer-reviewed original research articles discussing nosZ and published from 2013 to 2019 showed that the percentage of articles evaluating or mentioning Clade II nosZ increased from 5% in 2013 to only 22% in 2019. The census revealed that the slowly spreading awareness of Clade II nosZ may result in part from disciplinary silos, with the percentage of nosZ articles mentioning Clade II nosZ ranging from 0% in Agriculture and Agronomy journals to 32% in Multidisciplinary Sciences journals. In addition, inconsistent nomenclature for Clade I nosZ and Clade II nosZ, with 17 different terminologies used in the literature, may have created confusion about the two distinct groups of N2 O reducers. We provide recommendations to accelerate advances in understanding the role of the diversity of N2 O reducers in regulating soil N2 O emissions.
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Affiliation(s)
- Jun Shan
- State Key Laboratory of Soil and Sustainable Agriculture, Changshu National Agro-Ecosystem Observation and Research Station, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China
| | - Robert A Sanford
- Department of Geology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Joanne Chee-Sanford
- Global Change and Photosynthesis Research Unit, United States Department of Agriculture - Agricultural Research Station,, Urbana, IL, USA
| | - Sean K Ooi
- Program in Ecology, Evolution, and Conservation Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Frank E Löffler
- Center for Environmental Biotechnology, Department of Microbiology, Department of Civil and Environmental Engineering, Department of Biosystems Engineering and Soil Science, University of Tennessee, Knoxville, TN, USA
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Konstantinos T Konstantinidis
- School of Civil and Environmental Engineering and School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA
| | - Wendy H Yang
- Departments of Plant Biology and Geology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
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15
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Aldossari N, Ishii S. Isolation of cold-adapted nitrate-reducing fungi that have potential to increase nitrate removal in woodchip bioreactors. J Appl Microbiol 2020; 131:197-207. [PMID: 33222401 DOI: 10.1111/jam.14939] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 11/12/2020] [Accepted: 11/17/2020] [Indexed: 11/27/2022]
Abstract
AIMS The aim of this study was to obtain cold-adapted denitrifying fungi that could be used for bioaugmentation in woodchip bioreactors to remove nitrate from agricultural subsurface drainage water. METHODS AND RESULTS We isolated a total of 91 nitrate-reducing fungal strains belonging to Ascomycota and Mucoromycota from agricultural soil and a woodchip bioreactor under relatively cold conditions (5 and 15°C). When these strains were incubated with 15 N-labelled nitrate, 29 N2 was frequently produced, suggesting the occurrence of co-denitrification (microbially mediated nitrosation). Two strains also produced 30 N2 , indicating their ability to reduce N2 O. Of the 91 nitrate-reducing fungal strains, fungal nitrite reductase gene (nirK) and cytochrome P450 nitric oxide reductase gene (p450nor) were detected by PCR in 34 (37%) and 11 (12%) strains, respectively. Eight strains possessed both nirK and p450nor, further verifying their denitrification capability. In addition, most strains degraded cellulose under denitrification condition. CONCLUSIONS Diverse nitrate-reducing fungi were isolated from soil and a woodchip bioreactor. These fungi reduced nitrate to gaseous N forms at relatively low temperatures. These cold-adapted, cellulose-degrading and nitrate-reducing fungi could support themselves and other denitrifiers in woodchip bioreactors. SIGNIFICANCE AND IMPACT OF THE STUDY The cold-adapted, cellulose-degrading and nitrate-reducing fungi isolated in this study could be useful to enhance nitrate removal in woodchip bioreactors under low-temperature conditions.
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Affiliation(s)
- N Aldossari
- Department of Soil, Water, and Climate, University of Minnesota, Saint Paul, MN, USA
| | - S Ishii
- Department of Soil, Water, and Climate, University of Minnesota, Saint Paul, MN, USA.,BioTechnology Institute, University of Minnesota, Saint Paul, MN, USA
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16
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Chlamydomonas reinhardtii, an Algal Model in the Nitrogen Cycle. PLANTS 2020; 9:plants9070903. [PMID: 32708782 PMCID: PMC7412212 DOI: 10.3390/plants9070903] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 07/12/2020] [Accepted: 07/13/2020] [Indexed: 02/06/2023]
Abstract
Nitrogen (N) is an essential constituent of all living organisms and the main limiting macronutrient. Even when dinitrogen gas is the most abundant form of N, it can only be used by fixing bacteria but is inaccessible to most organisms, algae among them. Algae preferentially use ammonium (NH4+) and nitrate (NO3−) for growth, and the reactions for their conversion into amino acids (N assimilation) constitute an important part of the nitrogen cycle by primary producers. Recently, it was claimed that algae are also involved in denitrification, because of the production of nitric oxide (NO), a signal molecule, which is also a substrate of NO reductases to produce nitrous oxide (N2O), a potent greenhouse gas. This review is focused on the microalga Chlamydomonas reinhardtii as an algal model and its participation in different reactions of the N cycle. Emphasis will be paid to new actors, such as putative genes involved in NO and N2O production and their occurrence in other algae genomes. Furthermore, algae/bacteria mutualism will be considered in terms of expanding the N cycle to ammonification and N fixation, which are based on the exchange of carbon and nitrogen between the two organisms.
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17
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Keuschnig C, Gorfer M, Li G, Mania D, Frostegård Å, Bakken L, Larose C. NO and N 2 O transformations of diverse fungi in hypoxia: evidence for anaerobic respiration only in Fusarium strains. Environ Microbiol 2020; 22:2182-2195. [PMID: 32157782 DOI: 10.1111/1462-2920.14980] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 02/21/2020] [Accepted: 03/07/2020] [Indexed: 11/30/2022]
Abstract
Fungal denitrification is claimed to produce non-negligible amounts of N2 O in soils, but few tested species have shown significant activity. We hypothesized that denitrifying fungi would be found among those with assimilatory nitrate reductase, and tested 20 such batch cultures for their respiratory metabolism, including two positive controls, Fusarium oxysporum and Fusarium lichenicola, throughout the transition from oxic to anoxic conditions in media supplemented with NO 2 - . Enzymatic reduction of NO 2 - (NIR) and NO (NOR) was assessed by correcting measured NO- and N2 O-kinetics for abiotic NO- and N2 O-production (sterile controls). Significant anaerobic respiration was only confirmed for the positive controls and for two of three Fusarium solani cultures. The NO kinetics in six cultures showed NIR but not NOR activity, observed through the accumulation of NO. Others had NOR but not NIR activity, thus reducing abiotically produced NO to N2 O. The presence of candidate genes (nirK and p450nor) was confirmed in the positive controls, but not in some of the NO or N2 O accumulating cultures. Based on our results, we conclude that only the Fusarium cultures were able to sustain anaerobic respiration and produced low amounts of N2 O as a response to an abiotic NO production from the medium.
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Affiliation(s)
- Christoph Keuschnig
- Environmental Microbial Genomics, Laboratoire Ampère, CNRS UMR 5005, Ecole Centrale de Lyon, Université de Lyon, 69134, Ecully Cedex, France
| | - Markus Gorfer
- Bioresources, AIT Austrian Institute of Technology GmbH, Tulln, Austria
| | - Guofen Li
- Bioresources, AIT Austrian Institute of Technology GmbH, Tulln, Austria
| | - Daniel Mania
- Faculty of Chemistry, Biotechnology and Food Sciences, Norwegian University of Life Sciences, 1432, Aas, Norway
| | - Åsa Frostegård
- Faculty of Chemistry, Biotechnology and Food Sciences, Norwegian University of Life Sciences, 1432, Aas, Norway
| | - Lars Bakken
- Faculty of Chemistry, Biotechnology and Food Sciences, Norwegian University of Life Sciences, 1432, Aas, Norway
| | - Catherine Larose
- Environmental Microbial Genomics, Laboratoire Ampère, CNRS UMR 5005, Ecole Centrale de Lyon, Université de Lyon, 69134, Ecully Cedex, France
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18
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Zhao Y, Lim J, Xu J, Yu J, Zheng W. Nitric oxide as a developmental and metabolic signal in filamentous fungi. Mol Microbiol 2020; 113:872-882. [DOI: 10.1111/mmi.14465] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 01/15/2020] [Accepted: 01/15/2020] [Indexed: 12/19/2022]
Affiliation(s)
- Yanxia Zhao
- Key Laboratory for Biotechnology of Medicinal Plants Jiangsu Normal University Xuzhou China
| | - Jieyin Lim
- Departments of Bacteriology and Genetics Food Research Institute University of Wisconsin‐Madison Madison Wisconsin USA
| | - Jianyang Xu
- Department of Traditional Chinese Medicine General Hospital of Shenzhen University Shenzhen China
| | - Jae‐Hyuk Yu
- Departments of Bacteriology and Genetics Food Research Institute University of Wisconsin‐Madison Madison Wisconsin USA
- Department of Systems Biotechnology Konkuk University Seoul Republic of Korea
| | - Weifa Zheng
- Key Laboratory for Biotechnology of Medicinal Plants Jiangsu Normal University Xuzhou China
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19
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Abstract
Nitrous oxide (N2O), the third most important greenhouse gas in the atmosphere, is produced in great quantities by microalgae, but molecular mechanisms remain elusive. Here we show that the green microalga Chlamydomonas reinhardtii produces N2O in the light by a reduction of NO driven by photosynthesis and catalyzed by flavodiiron proteins, the dark N2O production being catalyzed by a cytochrome p450. Both mechanisms of N2O production are present in chlorophytes, but absent from diatoms. Our study provides an unprecedented mechanistic understanding of N2O production by microalgae, allowing a better assessment of N2O-producing hot spots in aquatic environments. Nitrous oxide (N2O), a potent greenhouse gas in the atmosphere, is produced mostly from aquatic ecosystems, to which algae substantially contribute. However, mechanisms of N2O production by photosynthetic organisms are poorly described. Here we show that the green microalga Chlamydomonas reinhardtii reduces NO into N2O using the photosynthetic electron transport. Through the study of C. reinhardtii mutants deficient in flavodiiron proteins (FLVs) or in a cytochrome p450 (CYP55), we show that FLVs contribute to NO reduction in the light, while CYP55 operates in the dark. Both pathways are active when NO is produced in vivo during the reduction of nitrites and participate in NO homeostasis. Furthermore, NO reduction by both pathways is restricted to chlorophytes, organisms particularly abundant in ocean N2O-producing hot spots. Our results provide a mechanistic understanding of N2O production in eukaryotic phototrophs and represent an important step toward a comprehensive assessment of greenhouse gas emission by aquatic ecosystems.
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20
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Gleason FH, Larkum AW, Raven JA, Manohar CS, Lilje O. Ecological implications of recently discovered and poorly studied sources of energy for the growth of true fungi especially in extreme environments. FUNGAL ECOL 2019. [DOI: 10.1016/j.funeco.2018.12.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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21
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Bohu T, Anand R, Noble R, Lintern M, Kaksonen AH, Mei Y, Cheng KY, Deng X, Veder JP, Bunce M, Power M, Verrall M. Evidence for fungi and gold redox interaction under Earth surface conditions. Nat Commun 2019; 10:2290. [PMID: 31123249 PMCID: PMC6533363 DOI: 10.1038/s41467-019-10006-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 04/09/2019] [Indexed: 11/11/2022] Open
Abstract
Microbial contribution to gold biogeochemical cycling has been proposed. However, studies have focused primarily on the influence of prokaryotes on gold reduction and precipitation through a detoxification-oriented mechanism. Here we show, fungi, a major driver of mineral bioweathering, can initiate gold oxidation under Earth surface conditions, which is of significance for dissolved gold species formation and distribution. Presence of the gold-oxidizing fungus TA_pink1, an isolate of Fusarium oxysporum, suggests fungi have the potential to substantially impact gold biogeochemical cycling. Our data further reveal that indigenous fungal diversity positively correlates with in situ gold concentrations. Hypocreales, the order of the gold-oxidizing fungus, show the highest centrality in the fungal microbiome of the auriferous environment. Therefore, we argue that the redox interaction between fungi and gold is critical and should be considered in gold biogeochemical cycling.
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Affiliation(s)
- Tsing Bohu
- CSIRO Mineral Resources, Australian Resources and Research Centre, Kensington, WA, 6151, Australia.
| | - Ravi Anand
- CSIRO Mineral Resources, Australian Resources and Research Centre, Kensington, WA, 6151, Australia
| | - Ryan Noble
- CSIRO Mineral Resources, Australian Resources and Research Centre, Kensington, WA, 6151, Australia
| | - Mel Lintern
- CSIRO Mineral Resources, Australian Resources and Research Centre, Kensington, WA, 6151, Australia
| | - Anna H Kaksonen
- CSIRO Land and Water, Private Bag No.5, Wembley, WA, 6913, Australia
- School of Biomedical Sciences, University of Western Australia, Crawley, WA, 6009, Australia
| | - Yuan Mei
- CSIRO Mineral Resources, Australian Resources and Research Centre, Kensington, WA, 6151, Australia
| | - Ka Yu Cheng
- CSIRO Land and Water, Private Bag No.5, Wembley, WA, 6913, Australia
- School of Engineering and Information Technology, Murdoch University, Perth, WA, 6150, Australia
| | - Xiao Deng
- CSIRO Land and Water, Private Bag No.5, Wembley, WA, 6913, Australia
| | - Jean-Pierre Veder
- John de Laeter Centre, Curtin University, Bentley, WA, 6102, Australia
| | - Michael Bunce
- Trace and Environmental DNA (TrEnD) Laboratory, Department of Environment and Agriculture, Curtin University, Bentley, WA, 6102, Australia
| | - Matthew Power
- Trace and Environmental DNA (TrEnD) Laboratory, Department of Environment and Agriculture, Curtin University, Bentley, WA, 6102, Australia
| | - Mike Verrall
- CSIRO Mineral Resources, Australian Resources and Research Centre, Kensington, WA, 6151, Australia
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Yoon S, Song B, Phillips RL, Chang J, Song MJ. Ecological and physiological implications of nitrogen oxide reduction pathways on greenhouse gas emissions in agroecosystems. FEMS Microbiol Ecol 2019; 95:5488431. [DOI: 10.1093/femsec/fiz066] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2018] [Accepted: 05/10/2019] [Indexed: 11/12/2022] Open
Abstract
ABSTRACT
Microbial reductive pathways of nitrogen (N) oxides are highly relevant to net emissions of greenhouse gases (GHG) from agroecosystems. Several biotic and abiotic N-oxide reductive pathways influence the N budget and net GHG production in soil. This review summarizes the recent findings of N-oxide reduction pathways and their implications to GHG emissions in agroecosystems and proposes several mitigation strategies. Denitrification is the primary N-oxide reductive pathway that results in direct N2O emissions and fixed N losses, which add to the net carbon footprint. We highlight how dissimilatory nitrate reduction to ammonium (DNRA), an alternative N-oxide reduction pathway, may be used to reduce N2O production and N losses via denitrification. Implications of nosZ abundance and diversity and expressed N2O reductase activity to soil N2O emissions are reviewed with focus on the role of the N2O-reducers as an important N2O sink. Non-prokaryotic N2O sources, e.g. fungal denitrification, codenitrification and chemodenitrification, are also summarized to emphasize their potential significance as modulators of soil N2O emissions. Through the extensive review of these recent scientific advancements, this study posits opportunities for GHG mitigation through manipulation of microbial N-oxide reductive pathways in soil.
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Affiliation(s)
- Sukhwan Yoon
- Department of Civil and Environmental Engineering, KAIST, 291 Daehakro, Yuseonggu, Daejeon 34141, South Korea
| | - Bongkeun Song
- Department of Biological Sciences, Virginia Institute of Marine Sciences, College of William and Mary, 1375 Greate Rd, Gloucester Point, VA 23062, USA
| | - Rebecca L Phillips
- Ecological Insights Corporation, 130 69th Street SE, Hazelton, ND 58544, USA
| | - Jin Chang
- Department of Civil and Environmental Engineering, KAIST, 291 Daehakro, Yuseonggu, Daejeon 34141, South Korea
| | - Min Joon Song
- Department of Civil and Environmental Engineering, KAIST, 291 Daehakro, Yuseonggu, Daejeon 34141, South Korea
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24
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Hunt AP, Lehnert N. The Thiolate Trans Effect in Heme {FeNO}6 Complexes and Beyond: Insight into the Nature of the Push Effect. Inorg Chem 2019; 58:11317-11332. [DOI: 10.1021/acs.inorgchem.9b00091] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Andrew P. Hunt
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | - Nicolai Lehnert
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
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25
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Ma Y, Zilles JL, Kent AD. An evaluation of primers for detecting denitrifiers via their functional genes. Environ Microbiol 2019; 21:1196-1210. [PMID: 30724437 DOI: 10.1111/1462-2920.14555] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 01/29/2019] [Accepted: 02/01/2019] [Indexed: 12/11/2022]
Abstract
Microbial populations provide nitrogen cycling ecosystem services at the nexus of agriculture, environmental quality and climate change. Denitrification, in particular, impacts socio-environmental systems in both positive and negative ways, through reduction of aquatic and atmospheric nitrogen pollution, but also reduction of soil fertility and production of greenhouse gases. However, denitrification rates are quite variable in time and space, and therefore difficult to model. Microbial ecology is working to improve the predictive ecology of denitrifiers by quantifying and describing the diversity of microbial functional groups. However, metagenomic sequencing has revealed previously undescribed diversity within these functional groups, and highlighted a need to reevaluate coverage of existing DNA primers for denitrification functional genes. We provide here a comprehensive in silico evaluation of primer sets that target diagnostic genes in the denitrification pathway. This analysis makes use of current DNA sequence data available for each functional gene. It contributes a comparative analysis of the strengths and limitations of each primer set for describing denitrifier functional groups. This analysis identifies genes for which development of new tools is needed, and aids in interpretation of existing datasets, both of which will facilitate application of molecular methods to further develop the predictive ecology of denitrifiers.
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Affiliation(s)
- Yanjun Ma
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Julie L Zilles
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Angela D Kent
- Department of Natural Resources and Environmental Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, USA
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Xu H, Sheng R, Xing X, Zhang W, Hou H, Liu Y, Qin H, Chen C, Wei W. Characterization of Fungal nirK-Containing Communities and N 2O Emission From Fungal Denitrification in Arable Soils. Front Microbiol 2019; 10:117. [PMID: 30778342 PMCID: PMC6369356 DOI: 10.3389/fmicb.2019.00117] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2018] [Accepted: 01/18/2019] [Indexed: 11/25/2022] Open
Abstract
Fungal denitrifiers play important roles in soil nitrogen cycling, but we have very limited knowledge about their distribution and functions in ecosystems. In this study, three types of arable soils were collected across different climate zones in China, including quaternary red clay soils, alluvial soils, and black soils. The composition and abundance of fungal nirK-containing denitrifiers was determined by MiSeq high-throughput sequencing and qPCR, respectively. Furthermore, a substrate-induced inhibition approach was used to explore N2O emissions from fungal denitrification. The results showed that the arable soils contained a wide range of nirK-containing fungal denitrifiers, with four orders and eight genera. Additionally, approximately 57.30% of operational taxonomic unit (OTUs) belonged to unclassified nirK-containing fungi. Hypocreales was the most predominant order, with approximately 40.51% of the total number of OTUs, followed by Sordariales, Eurotiales, and Mucorales. It was further indicated that 53% of fungal nirK OTUs were shared by the three types of soils (common), and this group of fungi comprised about 98% of the total relative abundance of the nirK-containing population, indicating that the distribution of fungal nirK-containing denitrifiers was quite homogenous among the soil types. These common OTUs were determined by multiple soil characteristics, while the composition of unique OTUs was manipulated by the specific properties of each soil type. Furthermore, fungal N2O emissions were significantly and positively correlated with fungal nirK abundance in the soils, whereas it was not clearly related to fungal nirK compositions. In conclusion, although the arable soils hosted diverse nirK-containing fungal denitrifiers, fungal nirK compositions were highly homogenous among the soil types, which could be a consequence of enduring agricultural practices. The abundance of fungal nirK-containing denitrifiers, rather than their composition, may play more significant roles in relation to N2O emission from fungal denitrification.
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Affiliation(s)
- Huifang Xu
- Key Laboratory of Agro-Ecological Processes in Subtropical Regions and Taoyuan Station of Agro-Ecology Research, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, China.,College of Resource and Environment, University of Chinese Academy of Sciences, Beijing, China
| | - Rong Sheng
- Key Laboratory of Agro-Ecological Processes in Subtropical Regions and Taoyuan Station of Agro-Ecology Research, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, China
| | - Xiaoyi Xing
- Key Laboratory of Agro-Ecological Processes in Subtropical Regions and Taoyuan Station of Agro-Ecology Research, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, China.,College of Resource and Environment, University of Chinese Academy of Sciences, Beijing, China
| | - Wenzhao Zhang
- Key Laboratory of Agro-Ecological Processes in Subtropical Regions and Taoyuan Station of Agro-Ecology Research, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, China
| | - Haijun Hou
- Key Laboratory of Agro-Ecological Processes in Subtropical Regions and Taoyuan Station of Agro-Ecology Research, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, China
| | - Yi Liu
- Key Laboratory of Agro-Ecological Processes in Subtropical Regions and Taoyuan Station of Agro-Ecology Research, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, China
| | - Hongling Qin
- Key Laboratory of Agro-Ecological Processes in Subtropical Regions and Taoyuan Station of Agro-Ecology Research, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, China
| | - Chunlan Chen
- Key Laboratory of Agro-Ecological Processes in Subtropical Regions and Taoyuan Station of Agro-Ecology Research, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, China
| | - Wenxue Wei
- Key Laboratory of Agro-Ecological Processes in Subtropical Regions and Taoyuan Station of Agro-Ecology Research, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, China
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Zhang H, Zhao Z, Kang P, Wang Y, Feng J, Jia J, Zhang Z. Biological nitrogen removal and metabolic characteristics of a novel aerobic denitrifying fungus Hanseniaspora uvarum strain KPL108. BIORESOURCE TECHNOLOGY 2018; 267:569-577. [PMID: 30053715 DOI: 10.1016/j.biortech.2018.07.073] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2018] [Revised: 07/12/2018] [Accepted: 07/14/2018] [Indexed: 06/08/2023]
Abstract
A novel aerobic denitrifying fungal strain KPL108 was isolated from the sediment of Jinpen drinking water reservoir and identified as Hanseniaspora uvarum. Strain KPL108 removed 99% of nitrate without nitrite accumulation under aerobic conditions, while the total organic carbon removal efficiency was 93%. KPL108 expressed fungal specific denitrifying gene p450nor. Nitrogen balance exhibited that approximately 92% of the initial nitrate was removed as gaseous products. Based on 13C-isotope labeling tracer, pentose phosphate pathway and tricarboxylic acid cycle were highly active in intracellular central carbon metabolism of strain KPL108. Response surface methodology revealed that the maximum total nitrogen removal efficiency occurred with the optimized parameters: C/N ratio of 6.4, pH of 8.2, 28.5 °C and 109.7 rpm. Collectively, the results from the present study indicate that strain KPL108 has aerobic denitrification ability, which has a great potential application for nitrogenous wastewater treatment.
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Affiliation(s)
- Haihan Zhang
- Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China; Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China; School of Environmental and Municipal Engineering, Institute of Environmental Microbial Technology, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China.
| | - Zhenfang Zhao
- Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China; Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China; School of Environmental and Municipal Engineering, Institute of Environmental Microbial Technology, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China
| | - Pengliang Kang
- Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China; Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China; School of Environmental and Municipal Engineering, Institute of Environmental Microbial Technology, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China
| | - Yue Wang
- Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China; Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China; School of Environmental and Municipal Engineering, Institute of Environmental Microbial Technology, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China
| | - Ji Feng
- Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China; Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China; School of Environmental and Municipal Engineering, Institute of Environmental Microbial Technology, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China
| | - Jingyu Jia
- Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China; Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China; School of Environmental and Municipal Engineering, Institute of Environmental Microbial Technology, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China
| | - Zhonghui Zhang
- Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China; Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China; School of Environmental and Municipal Engineering, Institute of Environmental Microbial Technology, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China
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Higgins SA, Schadt CW, Matheny PB, Löffler FE. Phylogenomics Reveal the Dynamic Evolution of Fungal Nitric Oxide Reductases and Their Relationship to Secondary Metabolism. Genome Biol Evol 2018; 10:2474-2489. [PMID: 30165640 PMCID: PMC6161760 DOI: 10.1093/gbe/evy187] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/23/2018] [Indexed: 12/16/2022] Open
Abstract
Fungi expressing P450nor, an unconventional nitric oxide (NO) reducing cytochrome P450, are considered significant contributors to environmental nitrous oxide (N2O) emissions. Despite extensive efforts, fungal contributions to N2O emissions remain uncertain. For example, the majority of N2O emitted from antibiotic-amended soil microcosms is attributed to fungal activity, yet axenic fungal cultures do not couple N-oxyanion respiration to growth and these fungi produce only minor quantities of N2O. To assist in reconciling these conflicting observations and produce a benchmark genomic analysis of fungal denitrifiers, genes underlying denitrification were examined in >700 fungal genomes. Of 167 p450nor—containing genomes identified, 0, 30, and 48 also harbored the denitrification genes narG, napA, or nirK, respectively. Compared with napA and nirK, p450nor was twice as abundant and exhibited 2–5-fold more gene duplications, losses, and transfers, indicating a disconnect between p450nor presence and denitrification potential. Furthermore, cooccurrence of p450nor with genes encoding NO-detoxifying flavohemoglobins (Spearman r = 0.87, p = 1.6e−10) confounds hypotheses regarding P450nor’s primary role in NO detoxification. Instead, ancestral state reconstruction united P450nor with actinobacterial cytochrome P450s (CYP105) involved in secondary metabolism (SM) and 19 (11%) p450nor-containing genomic regions were predicted to be SM clusters. Another 40 (24%) genomes harbored genes nearby p450nor predicted to encode hallmark SM functions, providing additional contextual evidence linking p450nor to SM. These findings underscore the potential physiological implications of widespread p450nor gene transfer, support the undiscovered affiliation of p450nor with fungal SM, and challenge the hypothesis of p450nor’s primary role in denitrification.
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Affiliation(s)
- Steven A Higgins
- Department of Microbiology, University of Tennessee, Knoxville.,Biosciences Division, Oak Ridge National Laboratory, Oak Ridge
| | - Christopher W Schadt
- Department of Microbiology, University of Tennessee, Knoxville.,Biosciences Division, Oak Ridge National Laboratory, Oak Ridge.,University of Tennessee and Oak Ridge National Laboratory (UT-ORNL), Joint Institute for Biological Sciences (JIBS), Oak Ridge
| | - Patrick B Matheny
- Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville
| | - Frank E Löffler
- Department of Microbiology, University of Tennessee, Knoxville.,Biosciences Division, Oak Ridge National Laboratory, Oak Ridge.,University of Tennessee and Oak Ridge National Laboratory (UT-ORNL), Joint Institute for Biological Sciences (JIBS), Oak Ridge.,Department of Civil and Environmental Engineering, University of Tennessee, Knoxville.,Department of Biosystems Engineering and Soil Science, University of Tennessee, Knoxville.,Center for Environmental Biotechnology, University of Tennessee, Knoxville
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Is Endophyte-Plant Co-Denitrification a Source of Nitrous Oxides Emission? —An Experimental Investigation with Soybean. AGRONOMY-BASEL 2018. [DOI: 10.3390/agronomy8070108] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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30
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Denitrification by Anaeromyxobacter dehalogenans, a Common Soil Bacterium Lacking the Nitrite Reductase Genes nirS and nirK. Appl Environ Microbiol 2018; 84:AEM.01985-17. [PMID: 29196287 DOI: 10.1128/aem.01985-17] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Accepted: 11/27/2017] [Indexed: 11/20/2022] Open
Abstract
The versatile soil bacterium Anaeromyxobacter dehalogenans lacks the hallmark denitrification genes nirS and nirK (encoding NO2 -→NO reductases) and couples growth to NO3 - reduction to NH4 + (respiratory ammonification) and to N2O reduction to N2 A. dehalogenans also grows by reducing Fe(III) to Fe(II), which chemically reacts with NO2 - to form N2O (i.e., chemodenitrification). Following the addition of 100 μmol of NO3 - or NO2 - to Fe(III)-grown axenic cultures of A. dehalogenans, 54 (±7) μmol and 113 (±2) μmol N2O-N, respectively, were produced and subsequently consumed. The conversion of NO3 - to N2 in the presence of Fe(II) through linked biotic-abiotic reactions represents an unrecognized ecophysiology of A. dehalogenans The new findings demonstrate that the assessment of gene content alone is insufficient to predict microbial denitrification potential and N loss (i.e., the formation of gaseous N products). A survey of complete bacterial genomes in the NCBI Reference Sequence database coupled with available physiological information revealed that organisms lacking nirS or nirK but with Fe(III) reduction potential and genes for NO3 - and N2O reduction are not rare, indicating that NO3 - reduction to N2 through linked biotic-abiotic reactions is not limited to A. dehalogenans Considering the ubiquity of iron in soils and sediments and the broad distribution of dissimilatory Fe(III) and NO3 - reducers, denitrification independent of NO-forming NO2 - reductases (through combined biotic-abiotic reactions) may have substantial contributions to N loss and N2O flux.IMPORTANCE Current attempts to gauge N loss from soils rely on the quantitative measurement of nirK and nirS genes and/or transcripts. In the presence of iron, the common soil bacterium Anaeromyxobacter dehalogenans is capable of denitrification and the production of N2 without the key denitrification genes nirK and nirS Such chemodenitrifiers denitrify through combined biotic and abiotic reactions and have potentially large contributions to N loss to the atmosphere and fill a heretofore unrecognized ecological niche in soil ecosystems. The findings emphasize that the comprehensive understanding of N flux and the accurate assessment of denitrification potential can be achieved only when integrated studies of interlinked biogeochemical cycles are performed.
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Genomics and Ecology of Novel N 2O-Reducing Microorganisms. Trends Microbiol 2017; 26:43-55. [PMID: 28803698 DOI: 10.1016/j.tim.2017.07.003] [Citation(s) in RCA: 205] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Revised: 06/29/2017] [Accepted: 07/14/2017] [Indexed: 11/22/2022]
Abstract
Microorganisms with the capacity to reduce the greenhouse gas nitrous oxide (N2O) to harmless dinitrogen gas are receiving increased attention due to increasing N2O emissions (and our need to mitigate climate change) and to recent discoveries of novel N2O-reducing bacteria and archaea. The diversity of denitrifying and nondenitrifying microorganisms with capacity for N2O reduction was recently shown to be greater than previously expected. A formerly overlooked group (clade II) in the environment include a large fraction of nondenitrifying N2O reducers, which could be N2O sinks without major contribution to N2O formation. We review the recent advances about fundamental understanding of the genomics, physiology, and ecology of N2O reducers and the importance of these findings for curbing N2O emissions.
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Novel P450nor Gene Detection Assay Used To Characterize the Prevalence and Diversity of Soil Fungal Denitrifiers. Appl Environ Microbiol 2016; 82:4560-4569. [PMID: 27208113 DOI: 10.1128/aem.00231-16] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 05/16/2016] [Indexed: 02/03/2023] Open
Abstract
UNLABELLED Denitrifying fungi produce nitrous oxide (N2O), a potent greenhouse gas, as they generally lack the ability to convert N2O to dinitrogen. Contrary to the case for bacterial denitrifiers, the prevalence and diversity of denitrifying fungi found in the environment are not well characterized. In this study, denitrifying fungi were isolated from various soil ecosystems, and novel PCR primers targeting the P450nor gene, encoding the enzyme responsible for the conversion of nitric oxide to N2O, were developed, validated, and used to study the diversity of cultivable fungal denitrifiers. This PCR assay was also used to detect P450nor genes directly from environmental soil samples. Fungal denitrification capabilities were further validated using an N2O gas detection assay and a PCR assay targeting the nirK gene. A collection of 492 facultative anaerobic fungi was isolated from 15 soil ecosystems and taxonomically identified by sequencing the internal transcribed spacer sequence. Twenty-seven fungal denitrifiers belonging to 10 genera had the P450nor and the nirK genes and produced N2O from nitrite. N2O production is reported in strains not commonly known as denitrifiers, such as Byssochlamys nivea, Volutella ciliata, Chloridium spp., and Trichocladium spp. The prevalence of fungal denitrifiers did not follow a soil ecosystem distribution; however, a higher diversity was observed in compost and agricultural soils. The phylogenetic trees constructed using partial P450nor and nirK gene sequences revealed that both genes clustered taxonomically closely related strains together. IMPORTANCE A PCR assay targeting the P450nor gene involved in fungal denitrification was developed and validated. The newly developed P450nor primers were used on fungal DNA extracted from a collection of fungi isolated from various soil environments and on DNA directly extracted from soil. The results indicated that approximatively 25% of all isolated fungi possessed this gene and were able to convert nitrite to N2O. All soil samples from which denitrifying fungi were isolated also tested positive for the presence of P450nor The P450nor gene detection assay was reliable in detecting a large diversity of fungal denitrifiers. Due to the lack of homology existing between P450nor and bacterial denitrification genes, it is expected that this assay will become a tool of choice for studying fungal denitrifiers.
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