The Experts below are selected from a list of 2073 Experts worldwide ranked by ideXlab platform
Sara Hallin - One of the best experts on this subject based on the ideXlab platform.
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life on n2o deciphering the ecophysiology of n2o respiring bacterial communities in a continuous culture
The ISME Journal, 2018Co-Authors: Monica Conthe, Gijs J Kuenen, Robbert Kleerebezem, Lea Wittorf, Mark C M Van Loosdrecht, Sara HallinAbstract:Reduction of the greenhouse gas N2O to N2 is a trait among Denitrifying and non-Denitrifying Microorganisms having an N2O reductase, encoded by nosZ. The nosZ phylogeny has two major clades, I and II, and physiological differences among organisms within the clades may affect N2O emissions from ecosystems. To increase our understanding of the ecophysiology of N2O reducers, we determined the thermodynamic growth efficiency of N2O reduction and the selection of N2O reducers under N2O- or acetate-limiting conditions in a continuous culture enriched from a natural community with N2O as electron acceptor and acetate as electron donor. The biomass yields were higher during N2O limitation, irrespective of dilution rate and community composition. The former was corroborated in a continuous culture of Pseudomonas stutzeri and was potentially due to cytotoxic effects of surplus N2O. Denitrifiers were favored over non-Denitrifying N2O reducers under all conditions and Proteobacteria harboring clade I nosZ dominated. The abundance of nosZ clade II increased when allowing for lower growth rates, but bacteria with nosZ clade I had a higher affinity for N2O, as defined by μmax/Ks. Thus, the specific growth rate is likely a key factor determining the composition of communities living on N2O respiration under growth-limited conditions.
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life on n 2 o deciphering the ecophysiology of n 2 o respiring bacterial communities in a continuous culture
The ISME Journal, 2018Co-Authors: Monica Conthe, Gijs J Kuenen, Robbert Kleerebezem, Lea Wittorf, Mark C M Van Loosdrecht, Sara HallinAbstract:Reduction of the greenhouse gas N2O to N2 is a trait among Denitrifying and non-Denitrifying Microorganisms having an N2O reductase, encoded by nosZ. The nosZ phylogeny has two major clades, I and II, and physiological differences among organisms within the clades may affect N2O emissions from ecosystems. To increase our understanding of the ecophysiology of N2O reducers, we determined the thermodynamic growth efficiency of N2O reduction and the selection of N2O reducers under N2O- or acetate-limiting conditions in a continuous culture enriched from a natural community with N2O as electron acceptor and acetate as electron donor. The biomass yields were higher during N2O limitation, irrespective of dilution rate and community composition. The former was corroborated in a continuous culture of Pseudomonas stutzeri and was potentially due to cytotoxic effects of surplus N2O. Denitrifiers were favored over non-Denitrifying N2O reducers under all conditions and Proteobacteria harboring clade I nosZ dominated. The abundance of nosZ clade II increased when allowing for lower growth rates, but bacteria with nosZ clade I had a higher affinity for N2O, as defined by μmax/Ks. Thus, the specific growth rate is likely a key factor determining the composition of communities living on N2O respiration under growth-limited conditions.
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ecology of Denitrifying prokaryotes in agricultural soil
Advances in Agronomy, 2007Co-Authors: Laurent Philippot, Sara Hallin, Michael SchloterAbstract:Denitrification is a microbial respiratory process during which soluble nitrogen oxides are used as an alternative electron acceptor when oxygen is limiting. It results in considerable loss of nitrogen, which is the most limiting nutrient for crop production in agriculture. Denitrification is also of environmental concern, since it is the main biological process responsible for emissions of nitrous oxide, one of the six greenhouse gases considered by the Kyoto protocol. In addition to natural variations, agroecosystems are characterized by the use of numerous practices, such as fertilization and pesticide application, which can influence denitrification rates. This has been widely documented in the literature, illustrating the complexity of the underlying mechanisms regulating this process. In the last decade, however, application of molecular biology approaches has given the opportunity to look behind denitrification rates and to describe genes, transcripts, and enzymes responsible for the process. In order to reduce denitrification in arable soil, it is important to understand how different factors influence denitrification and how the denitrifier community structure is related to in situ activity. This chapter focuses on the impact of natural events as well as agricultural practices on Denitrifying Microorganisms.
Mike S M Jetten - One of the best experts on this subject based on the ideXlab platform.
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changes in microbial community composition activity and greenhouse gas production upon inundation of drained iron rich peat soils
Soil Biology & Biochemistry, 2020Co-Authors: Mike S M Jetten, Anniek E E De Jong, Simon Guererrocruz, Josepha M H Van Diggelen, Annika Vaksmaa, Leon P M Lamers, A J P Smolders, Olivia RasigrafAbstract:Abstract Globally, large-scale land drainage has severely deteriorated the functioning and services of peatlands, making restoration plans of the utmost importance. Rewetting is essential for the restoration of drained peatlands, but the level of success including greenhouse gas (GHG) mitigation largely depends on the soil microbiome interactions under the prevailing biogeochemical conditions. Here, we investigated the effects of inundation of drained iron (Fe) -rich peat topsoils on nutrient release, surface water quality, GHG production and consumption, and on the composition and activity of the microbial community. The effect of the addition of different potential electron acceptors on methane (CH4) production and consumption were studied in incubation experiments. In response to inundation, porewater concentrations of Fe, total inorganic carbon, ammonium, and phosphorus increased. CH4 emissions increased in the control (i.e. without any additions) and Fe(III) oxide amended incubations upon inundation. This could be explained by the increase in the relative abundance of methanogens even though Fe(III) was previously hypothesized to lower methanogenic activity. In contrast, nitrite, nitrate, and sulfate-rich incubations inhibited methanogenesis. The prolonged exposure to nitrogen oxides stimulated denitrification with nitrous oxide (N2O) as the main gaseous product, together with an increase in the relative abundance of Denitrifying Microorganisms. Our results demonstrate that insights into the changes in microbial communities in relation to soil geochemistry explain differences in responses observed in different peat soils observed upon inundation. The increase in emissions of the potent GHGs CH4 and N2O from Fe-rich peat topsoils are a major adverse effect in the early stage of inundation.
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characterization of anammox hydrazine dehydrogenase a key n2 producing enzyme in the global nitrogen cycle
Journal of Biological Chemistry, 2016Co-Authors: Wouter J Maalcke, Mike S M Jetten, Joachim Reimann, Simon De Vries, Julea N Butt, Andreas Dietl, Nardy Kip, Ulrike Mersdorf, Thomas R M BarendsAbstract:Anaerobic ammonium-oxidizing (anammox) bacteria derive their energy for growth from the oxidation of ammonium with nitrite as the electron acceptor. N2, the end product of this metabolism, is produced from the oxidation of the intermediate, hydrazine (N2H4). Previously, we identified N2-producing hydrazine dehydrogenase (KsHDH) from the anammox organism Kuenenia stuttgartiensis as the gene product of kustc0694 and determined some of its catalytic properties. In the genome of K. stuttgartiensis, kustc0694 is one of 10 paralogs related to octaheme hydroxylamine (NH2OH) oxidoreductase (HAO). Here, we characterized KsHDH as a covalently cross-linked homotrimeric octaheme protein as found for HAO and HAO-related hydroxylamine-oxidizing enzyme kustc1061 from K. stuttgartiensis. Interestingly, the HDH trimers formed octamers in solution, each octamer harboring an amazing 192 c-type heme moieties. Whereas HAO and kustc1061 are capable of hydrazine oxidation as well, KsHDH was highly specific for this activity. To understand this specificity, we performed detailed amino acid sequence analyses and investigated the catalytic and spectroscopic (electronic absorbance, EPR) properties of KsHDH in comparison with the well defined HAO and kustc1061. We conclude that HDH specificity is most likely derived from structural changes around the catalytic heme 4 (P460) and of the electron-wiring circuit comprising seven His/His-ligated c-type hemes in each subunit. These nuances make HDH a globally prominent N2-producing enzyme, next to nitrous oxide (N2O) reductase from Denitrifying Microorganisms.
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nitrous oxide emission during wastewater treatment
Water Research, 2009Co-Authors: Marlies J Kampschreur, H Temmink, Robbert Kleerebezem, Mike S M Jetten, Mark C M Van LoosdrechtAbstract:Abstract Nitrous oxide (N 2 O), a potent greenhouse gas, can be emitted during wastewater treatment, significantly contributing to the greenhouse gas footprint. Measurements at lab-scale and full-scale wastewater treatment plants (WWTPs) have demonstrated that N 2 O can be emitted in substantial amounts during nitrogen removal in WWTPs, however, a large variation in reported emission values exists. Analysis of literature data enabled the identification of the most important operational parameters leading to N 2 O emission in WWTPs: (i) low dissolved oxygen concentration in the nitrification and denitrification stages, (ii) increased nitrite concentrations in both nitrification and denitrification stages, and (iii) low COD/N ratio in the denitrification stage. From the literature it remains unclear whether nitrifying or Denitrifying Microorganisms are the main source of N 2 O emissions. Operational strategies to prevent N 2 O emission from WWTPs are discussed and areas in which further research is urgently required are identified.
Robbert Kleerebezem - One of the best experts on this subject based on the ideXlab platform.
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life on n 2 o deciphering the ecophysiology of n 2 o respiring bacterial communities in a continuous culture
The ISME Journal, 2018Co-Authors: Monica Conthe, Gijs J Kuenen, Robbert Kleerebezem, Lea Wittorf, Mark C M Van Loosdrecht, Sara HallinAbstract:Reduction of the greenhouse gas N2O to N2 is a trait among Denitrifying and non-Denitrifying Microorganisms having an N2O reductase, encoded by nosZ. The nosZ phylogeny has two major clades, I and II, and physiological differences among organisms within the clades may affect N2O emissions from ecosystems. To increase our understanding of the ecophysiology of N2O reducers, we determined the thermodynamic growth efficiency of N2O reduction and the selection of N2O reducers under N2O- or acetate-limiting conditions in a continuous culture enriched from a natural community with N2O as electron acceptor and acetate as electron donor. The biomass yields were higher during N2O limitation, irrespective of dilution rate and community composition. The former was corroborated in a continuous culture of Pseudomonas stutzeri and was potentially due to cytotoxic effects of surplus N2O. Denitrifiers were favored over non-Denitrifying N2O reducers under all conditions and Proteobacteria harboring clade I nosZ dominated. The abundance of nosZ clade II increased when allowing for lower growth rates, but bacteria with nosZ clade I had a higher affinity for N2O, as defined by μmax/Ks. Thus, the specific growth rate is likely a key factor determining the composition of communities living on N2O respiration under growth-limited conditions.
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life on n2o deciphering the ecophysiology of n2o respiring bacterial communities in a continuous culture
The ISME Journal, 2018Co-Authors: Monica Conthe, Gijs J Kuenen, Robbert Kleerebezem, Lea Wittorf, Mark C M Van Loosdrecht, Sara HallinAbstract:Reduction of the greenhouse gas N2O to N2 is a trait among Denitrifying and non-Denitrifying Microorganisms having an N2O reductase, encoded by nosZ. The nosZ phylogeny has two major clades, I and II, and physiological differences among organisms within the clades may affect N2O emissions from ecosystems. To increase our understanding of the ecophysiology of N2O reducers, we determined the thermodynamic growth efficiency of N2O reduction and the selection of N2O reducers under N2O- or acetate-limiting conditions in a continuous culture enriched from a natural community with N2O as electron acceptor and acetate as electron donor. The biomass yields were higher during N2O limitation, irrespective of dilution rate and community composition. The former was corroborated in a continuous culture of Pseudomonas stutzeri and was potentially due to cytotoxic effects of surplus N2O. Denitrifiers were favored over non-Denitrifying N2O reducers under all conditions and Proteobacteria harboring clade I nosZ dominated. The abundance of nosZ clade II increased when allowing for lower growth rates, but bacteria with nosZ clade I had a higher affinity for N2O, as defined by μmax/Ks. Thus, the specific growth rate is likely a key factor determining the composition of communities living on N2O respiration under growth-limited conditions.
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nitrous oxide emission during wastewater treatment
Water Research, 2009Co-Authors: Marlies J Kampschreur, H Temmink, Robbert Kleerebezem, Mike S M Jetten, Mark C M Van LoosdrechtAbstract:Abstract Nitrous oxide (N 2 O), a potent greenhouse gas, can be emitted during wastewater treatment, significantly contributing to the greenhouse gas footprint. Measurements at lab-scale and full-scale wastewater treatment plants (WWTPs) have demonstrated that N 2 O can be emitted in substantial amounts during nitrogen removal in WWTPs, however, a large variation in reported emission values exists. Analysis of literature data enabled the identification of the most important operational parameters leading to N 2 O emission in WWTPs: (i) low dissolved oxygen concentration in the nitrification and denitrification stages, (ii) increased nitrite concentrations in both nitrification and denitrification stages, and (iii) low COD/N ratio in the denitrification stage. From the literature it remains unclear whether nitrifying or Denitrifying Microorganisms are the main source of N 2 O emissions. Operational strategies to prevent N 2 O emission from WWTPs are discussed and areas in which further research is urgently required are identified.
Monica Conthe - One of the best experts on this subject based on the ideXlab platform.
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life on n2o deciphering the ecophysiology of n2o respiring bacterial communities in a continuous culture
The ISME Journal, 2018Co-Authors: Monica Conthe, Gijs J Kuenen, Robbert Kleerebezem, Lea Wittorf, Mark C M Van Loosdrecht, Sara HallinAbstract:Reduction of the greenhouse gas N2O to N2 is a trait among Denitrifying and non-Denitrifying Microorganisms having an N2O reductase, encoded by nosZ. The nosZ phylogeny has two major clades, I and II, and physiological differences among organisms within the clades may affect N2O emissions from ecosystems. To increase our understanding of the ecophysiology of N2O reducers, we determined the thermodynamic growth efficiency of N2O reduction and the selection of N2O reducers under N2O- or acetate-limiting conditions in a continuous culture enriched from a natural community with N2O as electron acceptor and acetate as electron donor. The biomass yields were higher during N2O limitation, irrespective of dilution rate and community composition. The former was corroborated in a continuous culture of Pseudomonas stutzeri and was potentially due to cytotoxic effects of surplus N2O. Denitrifiers were favored over non-Denitrifying N2O reducers under all conditions and Proteobacteria harboring clade I nosZ dominated. The abundance of nosZ clade II increased when allowing for lower growth rates, but bacteria with nosZ clade I had a higher affinity for N2O, as defined by μmax/Ks. Thus, the specific growth rate is likely a key factor determining the composition of communities living on N2O respiration under growth-limited conditions.
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life on n 2 o deciphering the ecophysiology of n 2 o respiring bacterial communities in a continuous culture
The ISME Journal, 2018Co-Authors: Monica Conthe, Gijs J Kuenen, Robbert Kleerebezem, Lea Wittorf, Mark C M Van Loosdrecht, Sara HallinAbstract:Reduction of the greenhouse gas N2O to N2 is a trait among Denitrifying and non-Denitrifying Microorganisms having an N2O reductase, encoded by nosZ. The nosZ phylogeny has two major clades, I and II, and physiological differences among organisms within the clades may affect N2O emissions from ecosystems. To increase our understanding of the ecophysiology of N2O reducers, we determined the thermodynamic growth efficiency of N2O reduction and the selection of N2O reducers under N2O- or acetate-limiting conditions in a continuous culture enriched from a natural community with N2O as electron acceptor and acetate as electron donor. The biomass yields were higher during N2O limitation, irrespective of dilution rate and community composition. The former was corroborated in a continuous culture of Pseudomonas stutzeri and was potentially due to cytotoxic effects of surplus N2O. Denitrifiers were favored over non-Denitrifying N2O reducers under all conditions and Proteobacteria harboring clade I nosZ dominated. The abundance of nosZ clade II increased when allowing for lower growth rates, but bacteria with nosZ clade I had a higher affinity for N2O, as defined by μmax/Ks. Thus, the specific growth rate is likely a key factor determining the composition of communities living on N2O respiration under growth-limited conditions.
Jiři Dusek - One of the best experts on this subject based on the ideXlab platform.
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greenhouse gas emissions from a constructed wetland plants as important sources of carbon
Ecological Engineering, 2007Co-Authors: Tomas Picek, Hana Cižkova, Jiři DusekAbstract:Abstract Gas emissions (CO2, CH4, N2O) were studied in situ from the treatment bed of a constructed wetland with horizontal subsurface flow planted with Phragmites australis. The system treated municipal wastewater from 100 inhabitants and it was situated in South Bohemia, Czech Republic. The aims of the study were to estimate gas emissions and carbon balance of the whole system, and to evaluate the importance of plants to the whole system. Gases, water and plants were sampled from June till October 2004. Gas emissions ranged from 4 to 309 mg CO2-C m−2 h−1 and from 0 to 93 mg CH4-C m−2 h−1. N2O emission was negligible in the studied system; the only product of denitrification was N2. Only 10% of total carbon emissions were in the form of CH4. Amount of C emitted was higher than carbon input in the wastewater; it was calculated that between one fourth and one third of total carbon emissions originated in plants. The study documented the importance of plants as a source of available carbon for Microorganisms in constructed wetlands which are not heavily loaded with wastewater. This carbon is further transformed to gaseous forms and increases carbon emissions from the wetland. However, plant exudation also affects microbial processes and pore water quality. In this way, plants increase the efficiency of nitrogen removal from the wastewater by supporting Denitrifying Microorganisms with easily decomposable organic matter.