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Denitrifying bacteria

Sara Hallin, Laurent Philippot, Frank E Löffler, Robert A Sanford, Christopher M Jones
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...
August 10, 2017: Trends in Microbiology
Honglei Wang, Na Deng, Duoyang Wu, Shu Hu
A comprehensive understanding of how microbial associated with nitrogen (N) cycling respond to artificial vegetation restoration is still lacking, particularly in arid to semi-arid degraded ecosystems. We compared soil net N mineralization rates and the abundance of bacteria, archaea, and eleven N microbial genes on the northern Loess Plateau of China during the process of artificial vegetation restoration. The quantitative relationships between net N mineralization rates and N microbial genes were determined...
August 10, 2017: Scientific Reports
Co Thi Kinh, Toshikazu Suenaga, Tomoyuki Hori, Shohei Riya, Masaaki Hosomi, Barth F Smets, Akihiko Terada
The goal of this study was to investigate the effectiveness of a membrane-aerated biofilm reactor (MABR), a representative of counter-current substrate diffusion geometry, in mitigating nitrous oxide (N2O) emission. Two laboratory-scale reactors with the same dimensions but distinct biofilm geometries, i.e., a MABR and a conventional biofilm reactor (CBR) employing co-current substrate diffusion geometry, were operated to determine depth profiles of dissolved oxygen (DO), nitrous oxide (N2O), functional gene abundance and microbial community structure...
July 24, 2017: Water Research
Haifeng Qian, Tao Lu, Hao Song, Michel Lavoie, Jiahui Xu, Xiaoji Fan, Xiangliang Pan
Cyanobacterial blooms frequently occur in Lake Taihu (China), but the intertwined relationships between biotic and abiotic factors modulating the frequency and duration of the blooms remain enigmatic. To better understand the relationships between the key abiotic and biotic factors and cyanobacterial blooms, we measured the abundance and diversity of prokaryotic organisms by high-throughput sequencing, the abundance of key genes involved in microcystin production and nitrogen fixation or loss as well as several physicochemical parameters at several stations in Lake Taihu during a cyanobacterial bloom of Microcystis sp...
August 3, 2017: Bulletin of Environmental Contamination and Toxicology
Wei Zeng, Xinlong Bai, Yu Guo, Ning Li, Yongzhen Peng
To achieve energy-efficient denitrifying phosphorus removal via nitrite pathway from sewage, interaction of "Candidatus Accumulibacter" and nitrifying bacteria was investigated in a continuous-flow process. When nitrite in returned sludge of secondary settler was above 13mg/L, nitrite inhibition on anaerobic P-release of poly-phosphate organisms (PAOs) occurred. Clades IIC and IID were dominant, reaching 3.1%-11.9% of total bacteria. Clade IIC was sensitive to nitrite. Under low concentration of nitrite (<8mg/L), clade IIC primarily contributed to anoxic P-uptake...
October 2017: Enzyme and Microbial Technology
Yuke Peng, Lu Liu, Lijuan Jiang, Lin Xiao
Annually occurred cyanobacterial bloom aggravated eutrophication situation and changed the lacustrine ecosystem components. Recently, high concentration of bloom cyanobacteria had been found to accelerate total nitrogen (TN) removal. However, the contribution of cyanobacterial bloom to TN removal remained unclear. In this study, microcosms with different density of bloom cyanobacteria were constructed and quantitative PCR and structural equation modelling (SEM) were used to analyze the microbes, environmental variables and the causal relationship to TN removal...
July 25, 2017: Science of the Total Environment
L A Domeignoz-Horta, L Philippot, C Peyrard, D Bru, M C Breuil, F Bizouard, E Justes, B Mary, J Léonard, A Spor
Agriculture is the main source of terrestrial N2 O emissions, a potent greenhouse gas and the main cause of ozone depletion. The reduction of N2 O into N2 by microorganisms carrying the nitrous oxide reductase gene (nosZ) is the only known biological process eliminating this greenhouse gas. Recent studies showed that a previously unknown clade of N2 O-reducers (nosZII) was related to the potential capacity of the soil to act as a N2 O sink. However little is known about how this group responds to different agricultural practices...
July 28, 2017: Global Change Biology
Sergio Collado, Paula Oulego, Saúl Alonso, Mario Díaz
Flow cytometry has recently been presented as a research tool in the assessment of the viability/activity of activated sludge from municipal wastewater treatment plants, but it has not put in practice for industrial biotreatments yet. In this study, for the first time ever, the reliability and significance of the multiparameter flow cytometry applied to the biological nitrification-denitrification treatment of leachate have been evaluated. Using a double staining procedure (cFDA/PI), the viable, damaged, and dead subpopulations were determined, and the results were compared to those obtained with conventional methods, such as nitrogen and oxygen uptake rates or plate counting...
July 24, 2017: Environmental Science and Pollution Research International
María Teresa Zamarro, María J L Barragán, Manuel Carmona, José Luis García, Eduardo Díaz
Microorganisms able to degrade aromatic contaminants constitute potential valuable biocatalysts to deal with a significant reusable carbon fraction suitable for eco-efficient valorization processes. Metabolic engineering of anaerobic pathways for degradation and recycling of aromatic compounds is an almost unexplored field. In this work, we present the construction of a functional bzd cassette encoding the benzoyl-CoA central pathway for the anaerobic degradation of benzoate. The bzd cassette has been used to expand the ability of some denitrifying bacteria to use benzoate as sole carbon source under anaerobic conditions, and it paves the way for future pathway engineering of efficient anaerobic biodegraders of aromatic compounds whose degradation generates benzoyl-CoA as central intermediate...
July 24, 2017: Microbial Biotechnology
William D Orsi, Marco J L Coolen, Cornelia Wuchter, Lijun He, Kuldeep D More, Xabier Irigoien, Guillem Chust, Carl Johnson, Jordon D Hemingway, Mitchell Lee, Valier Galy, Liviu Giosan
Selection of microorganisms in marine sediment is shaped by energy-yielding electron acceptors for respiration that are depleted in vertical succession. However, some taxa have been reported to reflect past depositional conditions suggesting they have experienced weak selection after burial. In sediments underlying the Arabian Sea oxygen minimum zone (OMZ), we performed the first metagenomic profiling of sedimentary DNA at centennial-scale resolution in the context of a multi-proxy paleoclimate reconstruction...
July 20, 2017: Scientific Reports
V A J Rodrigues, E F A Mac Conell, D F C Dias, M von Sperling, J C de Araújo, J L Vasel
Accumulated sludge in polishing (maturation) ponds reduces the hydraulic retention time (smaller useful volume), and this could potentially lead to a decrease in performance. However, settled biomass, present in the sediments, can contribute to nitrogen removal by different mechanisms such as nitrification and denitrification. This study investigated the influence of the bottom sludge present in a shallow maturation pond treating the effluent from an anaerobic reactor on the nitrification and denitrification processes...
July 2017: Water Science and Technology: a Journal of the International Association on Water Pollution Research
Yihua Sun, Paul De Vos, Anne Willems
Until recently, it has not been generally known that some bacteria can contain the gene inventory for both denitrification and dissimilatory nitrate (NO3(-))/nitrite (NO2(-)) reduction to ammonium (NH4(+)) (DNRA). Detailed studies of these microorganisms could shed light on the differentiating environmental drivers of both processes without interference of organism-specific variation. Genome analysis of Bacillus azotoformans LMG 9581(T) shows a remarkable redundancy of dissimilatory nitrogen reduction, with multiple copies of each denitrification gene as well as DNRA genes nrfAH, but a reduced capacity for nitrogen assimilation, with no nas operon nor amtB gene...
July 19, 2017: Antonie Van Leeuwenhoek
Hongliang Dai, Yifeng Wu, Lihong Peng, Zheqin Dai, Xiang Li, Xiwu Lu
A sequencing batch reactor was operated to study the effects of influent Ca(2+) on the efficiency, bacterial population, and microbial metabolism of denitrifying phosphorus removal system. Results showed that high Ca(2+) loading (≥80mg/L) significantly inhibited the performance of simultaneous nitrogen and phosphorus removal. The abundance of phosphorus removal-related organisms (Dechloromonas and Candidatus Accumulibacter) decreased with increasing Ca(2+) concentration from 20 to 140mg/L, while the abundance of glycogen-accumulating organisms and other bacteria increased...
July 8, 2017: Bioresource Technology
Gang Guo, Di Wu, Tianwei Hao, Hamish Robert Mackey, Li Wei, Guanghao Chen
The performance of the denitrifying sulfur conversion-associated enhanced biological phosphorus removal (DS-EBPR) process tends to be unstable and requires further study and development. This in turn requires extensive study of the anaerobic metabolism in terms of its stoichiometry and kinetics. This study evaluates the corresponding responses of DS-EBPR to pH, as it significantly influences both stoichiometry and biochemical kinetics. The impacts of five representative pH values ranging between 6.5 and 8.5 on the anaerobic metabolism were investigated, followed by identification of the optimal pH for performance optimization...
July 12, 2017: Water Research
Shuang He, Yingmu Wang, Chuansong Li, Yancheng Li, Jian Zhou
The advanced treatment of secondary effluent was conducted in a two-stage deep sequencing constructed wetland (DSCW) which comprised a denitrification chamber (W1) and a nitrification chamber (W2). The results showed that a superior NO3(-)-N removal rate was observed in W1 with a C/N ratio of 6.5, and a high NH4(+)-N removal rate was obtained when the W2 was operated with 6-h duration of idle. In the long-term operation for 45days, the two-stage DSCW pilot system achieved high and stable removal of TN, NH4(+)-N and NO3(-)-N, which were 92...
June 29, 2017: Bioresource Technology
Tingting Tian, Nora F Y Tam, Qijie Zan, S G Cheung, Paul K S Shin, Y S Wong, Li Zhang, Zhanghe Chen
Constructed mangrove wetland has been used for wastewater treatment but its long-term performance has not been reported. One-year monitoring of a 10-years old horizontal subsurface-flow constructed mangrove wetland consisting of three belts, two with mangrove plants and one without, revealed that the system maintained high and stable removal percentages of organic matter and nutrients, and planted belts performed better than unplanted control. Substrates in belts planted with Aegiceras corniculatum or Kandelia obovata had higher abundance of ammonifiers, nitrifiers and denitrifiers but lower total heterotrophic bacteria than unplanted substrate...
July 12, 2017: Marine Pollution Bulletin
Jianhua Zhang, Qiong Zhang, Xiyao Li, Yuanyuan Miao, Yawen Sun, Miao Zhang, Yongzhen Peng
Obtaining desirable partial nitritation (PN) is crucial for successful application of the combined PN and anammox process. In this study, the partial nitritation and simultaneously phosphorus removal (PNSPR)(1) granular sludge reactor treating low-strength domestic sewage was rapidly started up in 67days through seeding denitrifying phosphorus removal (DPR)(2) sludge. The nitrite/ammonium ratio in effluent was approximately 1 and the nitrite accumulation rate (NAR) was more than 95%, about 93% of orthophosphate was removed...
June 26, 2017: Bioresource Technology
Sam Horrell, Demet Kekilli, Richard W Strange, Michael A Hough
Copper nitrite reductases (CuNiR) carry out the first committed step of the denitrification pathway of the global nitrogen cycle, the reduction of nitrite (NO2(-)) to nitric oxide (NO). As such, they are of major agronomic and environmental importance. CuNiRs occur primarily in denitrifying soil bacteria which carry out the overall reduction of nitrate to dinitrogen. In this article, we review the insights gained into copper nitrite reductase (CuNiR) function from three dimensional structures. We particularly focus on developments over the last decade, including insights from serial femtosecond crystallography using X-ray free electron lasers (XFELs) and from the recently discovered 3-domain CuNiRs...
July 12, 2017: Metallomics: Integrated Biometal Science
Vani Mohit, Alexander Culley, Connie Lovejoy, Frédéric Bouchard, Warwick F Vincent
Shallow lakes are common across the Arctic landscape and their ecosystem productivity is often dominated by benthic, cyanobacterial biofilms. Many of these water bodies freeze to the bottom and are biologically inactive during winter, but full freeze-up is becoming less common with Arctic warming. Here we analyzed the microbiome structure of newly discovered biofilms at the deepest site of a perennially ice-covered High Arctic lake as a model of polar microbial communities that remain unfrozen throughout the year...
2017: NPJ Biofilms and Microbiomes
Xin Sun, Amal Jayakumar, Bess B Ward
The ozone-depleting and greenhouse gas, nitrous oxide (N2O), is mainly consumed by the microbially mediated anaerobic process, denitrification. N2O consumption is the last step in canonical denitrification, and is also the least O2 tolerant step. Community composition of total and active N2O consuming bacteria was analyzed based on total (DNA) and transcriptionally active (RNA) nitrous oxide reductase (nosZ) genes using a functional gene microarray. The total and active nosZ communities were dominated by a limited number of nosZ archetypes, affiliated with bacteria from marine, soil and marsh environments...
2017: Frontiers in Microbiology
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