scholarly journals Comparison of different two-pathway models for describing the combined effect of DO and nitrite on the nitrous oxide production by ammonia-oxidizing bacteria

2016 ◽  
Vol 75 (3) ◽  
pp. 491-500 ◽  
Author(s):  
Longqi Lang ◽  
Mathieu Pocquet ◽  
Bing-Jie Ni ◽  
Zhiguo Yuan ◽  
Mathieu Spérandio
Keyword(s):  
Nitrous Oxide ◽  
Combined Effect ◽  
Ammonia Oxidizing Bacteria ◽  
N2o Production ◽  
Mathematical Structures ◽  
Nitrifier Denitrification ◽  
Nitrous Oxide Production ◽  
Pathway Models ◽  
Microbial Systems ◽  
Electron Carriers

The aim of this work is to compare the capability of two recently proposed two-pathway models for predicting nitrous oxide (N2O) production by ammonia-oxidizing bacteria (AOB) for varying ranges of dissolved oxygen (DO) and nitrite. The first model includes the electron carriers whereas the second model is based on direct coupling of electron donors and acceptors. Simulations are confronted to extensive sets of experiments (43 batches) from different studies with three different microbial systems. Despite their different mathematical structures, both models could well and similarly describe the combined effect of DO and nitrite on N2O production rate and emission factor. The model-predicted contributions for nitrifier denitrification pathway and hydroxylamine pathway also matched well with the available isotopic measurements. Based on sensitivity analysis, calibration procedures are described and discussed for facilitating the future use of those models.

scholarly journals Transcriptomic Response of Nitrosomonas europaea Transitioned from Ammonia- to Oxygen-Limited Steady-State Growth

mSystems ◽  
2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Christopher J. Sedlacek ◽  
Andrew T. Giguere ◽  
Michael D. Dobie ◽  
Brett L. Mellbye ◽  
Rebecca V. Ferrell ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Nitrous Oxide ◽  
Agricultural Soils ◽  
Nitrosomonas Europaea ◽  
Oxygen Limitation ◽  
Ammonia Oxidizing Bacteria ◽  
Content Type ◽  
Nitrifier Denitrification ◽  
Nitrous Oxide Production ◽  
Effect Of Oxygen

ABSTRACT Ammonia-oxidizing microorganisms perform the first step of nitrification, the oxidation of ammonia to nitrite. The bacterium Nitrosomonas europaea is the best-characterized ammonia oxidizer to date. Exposure to hypoxic conditions has a profound effect on the physiology of N. europaea, e.g., by inducing nitrifier denitrification, resulting in increased nitric and nitrous oxide production. This metabolic shift is of major significance in agricultural soils, as it contributes to fertilizer loss and global climate change. Previous studies investigating the effect of oxygen limitation on N. europaea have focused on the transcriptional regulation of genes involved in nitrification and nitrifier denitrification. Here, we combine steady-state cultivation with whole-genome transcriptomics to investigate the overall effect of oxygen limitation on N. europaea. Under oxygen-limited conditions, growth yield was reduced and ammonia-to-nitrite conversion was not stoichiometric, suggesting the production of nitrogenous gases. However, the transcription of the principal nitric oxide reductase (cNOR) did not change significantly during oxygen-limited growth, while the transcription of the nitrite reductase-encoding gene (nirK) was significantly lower. In contrast, both heme-copper-containing cytochrome c oxidases encoded by N. europaea were upregulated during oxygen-limited growth. Particularly striking was the significant increase in transcription of the B-type heme-copper oxidase, proposed to function as a nitric oxide reductase (sNOR) in ammonia-oxidizing bacteria. In the context of previous physiological studies, as well as the evolutionary placement of N. europaea’s sNOR with regard to other heme-copper oxidases, these results suggest sNOR may function as a high-affinity terminal oxidase in N. europaea and other ammonia-oxidizing bacteria. IMPORTANCE Nitrification is a ubiquitous microbially mediated process in the environment and an essential process in engineered systems such as wastewater and drinking water treatment plants. However, nitrification also contributes to fertilizer loss from agricultural environments, increasing the eutrophication of downstream aquatic ecosystems, and produces the greenhouse gas nitrous oxide. As ammonia-oxidizing bacteria are the most dominant ammonia-oxidizing microbes in fertilized agricultural soils, understanding their responses to a variety of environmental conditions is essential for curbing the negative environmental effects of nitrification. Notably, oxygen limitation has been reported to significantly increase nitric oxide and nitrous oxide production during nitrification. Here, we investigate the physiology of the best-characterized ammonia-oxidizing bacterium, Nitrosomonas europaea, growing under oxygen-limited conditions.

scholarly journals Nitrous oxide distribution and its origin in the central and eastern South Pacific Subtropical Gyre

2007 ◽  
Vol 4 (3) ◽  
pp. 1673-1702 ◽  
Author(s):  
J. Charpentier ◽  
L. Farias ◽  
N. Yoshida ◽  
N. Boontanon ◽  
P. Raimbault
Keyword(s):  
Nitrous Oxide ◽  
Coastal Upwelling ◽  
South Pacific ◽  
Site Preference ◽  
Intermediate Water ◽  
Low Oxygen ◽  
N2o Production ◽  
Oxide Production ◽  
Nitrifier Denitrification ◽  
Nitrous Oxide Production

Abstract. The biogeochemical mechanism of bacterial N2O production in the ocean has been the subject of many discussions in recent years. New isotopomeric tools can help further knowledge on N2O sources in natural environments. This research shows and compares hydrographic, nitrous oxide concentration, and N2O isotopic and isotopomeric data from three stations across the South Pacific Ocean, from the center of the subtropical oligotrophic gyre (~26° S; 114° W) to the upwelling zone along the central Chilean coast (~34° S). Althought AOU/N2O and NO3− trends support the idea that most of N2O source (mainly from intermediate water (200–1000 m)) come from nitrification, N2O isotopomeric composition (intramolecular distribution of 15N isotopes in N2O) reveals an abrupt change in the mechanism of nitrous oxide production, always observed through lower SP (site preference of 15N), at a high – stability layer, where particles could act as microsites and N2O would be produced by nitrifier denitrification (reduction of nitrite to nitrous oxide mediated by primary nitrifiers). There, nitrifier denitrification can account for 40% and 50% (center and east border of the gyre, respectively) of the nitrous oxide produced in this specific layer. This process could be associated with the deceleration of sinking organic particles in highly stable layers of the water column. In constrast, coastal upwelling system is characterized by oxygen deficient condition and some N deficit in a eutrophic system. Here, nitrous oxide accumulates up to 480% saturation, and isotopic and isotopomer signal show highly complex nitrous oxide production processes, which presumably reflect both the effect of nitrification and denitrification at low oxygen levels on N2O production, but non N2O consumption by denitrification was observed.

scholarly journals Transcriptomic response of Nitrosomonas europaea transitioned from ammonia- to oxygen-limited steady-state growth

2019 ◽  
Author(s):  
Christopher J. Sedlacek ◽  
Andrew T. Giguere ◽  
Michael D. Dobie ◽  
Brett L. Mellbye ◽  
Rebecca V Ferrell ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Nitrous Oxide ◽  
Agricultural Soils ◽  
Nitrosomonas Europaea ◽  
Oxygen Limitation ◽  
Ammonia Oxidizing Bacteria ◽  
Limited Growth ◽  
Nitrifier Denitrification ◽  
Nitrous Oxide Production ◽  
Effect Of Oxygen

AbstractAmmonia-oxidizing microorganisms perform the first step of nitrification, the oxidation of ammonia to nitrite. The bacterium Nitrosomonas europaea is the best characterized ammonia oxidizer to date. Exposure to hypoxic conditions has a profound effect on the physiology of N. europaea, e.g. by inducing nitrifier denitrification, resulting in increased nitric and nitrous oxide production. This metabolic shift is of major significance in agricultural soils, as it contributes to fertilizer loss and global climate change. Previous studies investigating the effect of oxygen limitation on N. europaea have focused on the transcriptional regulation of genes involved in nitrification and nitrifier denitrification. Here, we combine steady-state cultivation with whole genome transcriptomics to investigate the overall effect of oxygen limitation on N. europaea. Under oxygen-limited conditions, growth yield was reduced and ammonia to nitrite conversion was not stoichiometric, suggesting the production of nitrogenous gases. However, the transcription of the principal nitric oxide reductase (cNOR) did not change significantly during oxygen-limited growth, while the transcription of the nitrite reductase-encoding gene (nirK) was significantly lower. In contrast, both heme-copper containing cytochrome c oxidases encoded by N. europaea were upregulated during oxygen-limited growth. Particularly striking was the significant increase in transcription of the B-type heme-copper oxidase, proposed to function as a nitric oxide reductase (sNOR) in ammonia-oxidizing bacteria. In the context of previous physiological studies, as well as the evolutionary placement of N. europaea’s sNOR with regards to other heme-copper oxidases, these results suggest sNOR may function as a high-affinity terminal oxidase in N. europaea and other AOB.ImportanceNitrification is a ubiquitous, microbially mediated process in the environment and an essential process in engineered systems such as wastewater and drinking water treatment plants. However, nitrification also contributes to fertilizer loss from agricultural environments increasing the eutrophication of downstream aquatic ecosystems and produces the greenhouse gas nitrous oxide. As ammonia-oxidizing bacteria are the most dominant ammonia-oxidizing microbes in fertilized agricultural soils, understanding their response to a variety of environmental conditions is essential for curbing the negative environmental effects of nitrification. Notably, oxygen limitation has been reported to significantly increase nitric oxide and nitrous oxide production during nitrification. Here we investigate the physiology of the best characterized ammonia-oxidizing bacterium, Nitrosomonas europaea, growing under oxygen-limited conditions.

scholarly journals Low nitrous oxide production through nitrifier-denitrification in intermittent-feed high-rate nitritation reactors

2017 ◽  
Vol 123 ◽  
pp. 429-438 ◽  
Author(s):  
Qingxian Su ◽  
Chun Ma ◽  
Carlos Domingo-Félez ◽  
Anne Sofie Kiil ◽  
Bo Thamdrup ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
High Rate ◽  
Oxide Production ◽  
Nitrifier Denitrification ◽  
Nitrous Oxide Production

scholarly journals Biogeochemical controls and isotopic signatures of nitrous oxide production by a marine ammonia-oxidizing bacterium

2010 ◽  
Vol 7 (2) ◽  
pp. 3019-3059 ◽  
Author(s):  
C. H. Frame ◽  
K. L. Casciotti
Keyword(s):  
Nitrous Oxide ◽  
Stratospheric Ozone ◽  
N2o Production ◽  
Isotopic Signatures ◽  
Ammonium N ◽  
O2 Concentration ◽  
Nitrous Oxide Production ◽  
Global Estimates ◽  
Cell Densities ◽  
Ammonia Oxidizing Bacterium

Abstract. Nitrous oxide (N2O) is a trace gas that contributes to greenhouse warming of the atmosphere and stratospheric ozone depletion. The N2O yield from nitrification (moles N2O-N produced/mole ammonium-N consumed) has been used to estimate marine N2O production rates from measured nitrification rates and global estimates of oceanic export production. However, the N2O yield from nitrification is not constant. Previous culture-based measurements indicate that N2O yield increases as oxygen (O2) concentration decreases and as nitrite (NO2−) concentration increases. These results were obtained in substrate-rich conditions and may not reflect N2O production in the ocean. Here, we have measured yields of N2O from cultures of the marine β-proteobacterium Nitrosomonas marina C-113a as they grew on low-ammonium (50 μM) media. These yields were lower than previous reports, between 4×10−4 and 7×10−4 (moles N/mole N). The observed impact of O2 concentration on yield was also smaller than previously reported under all conditions except at high starting cell densities (1.5×10

scholarly journals Biogeochemical controls and isotopic signatures of nitrous oxide production by a marine ammonia-oxidizing bacterium

2010 ◽  
Vol 7 (9) ◽  
pp. 2695-2709 ◽  
Author(s):  
C. H. Frame ◽  
K. L. Casciotti
Keyword(s):  
Nitrous Oxide ◽  
Stratospheric Ozone ◽  
Nitrifying Bacteria ◽  
Site Preference ◽  
Ammonia Oxidizing Bacteria ◽  
N2o Production ◽  
O2 Concentration ◽  
Cell Densities ◽  
Dissolved O2

Abstract. Nitrous oxide (N2O) is a trace gas that contributes to the greenhouse effect and stratospheric ozone depletion. The N2O yield from nitrification (moles N2O-N produced per mole ammonium-N consumed) has been used to estimate marine N2O production rates from measured nitrification rates and global estimates of oceanic export production. However, the N2O yield from nitrification is not constant. Previous culture-based measurements indicate that N2O yield increases as oxygen (O2) concentration decreases and as nitrite (NO2−) concentration increases. Here, we have measured yields of N2O from cultures of the marine β-proteobacterium Nitrosomonas marina C-113a as they grew on low-ammonium (50 μM) media. These yields, which were typically between 4 × 10−4 and 7 × 10−4 for cultures with cell densities between 2 × 102 and 2.1 × 104 cells ml−1, were lower than previous reports for ammonia-oxidizing bacteria. The observed impact of O2 concentration on yield was also smaller than previously reported under all conditions except at high starting cell densities (1.5 × 106 cells ml−1), where 160-fold higher yields were observed at 0.5% O2 (5.1 μM dissolved O2) compared with 20% O2 (203 μM dissolved O2). At lower cell densities (2 × 102 and 2.1 × 104 cells ml−1), cultures grown under 0.5% O2 had yields that were only 1.25- to 1.73-fold higher than cultures grown under 20% O2. Thus, previously reported many-fold increases in N2O yield with dropping O2 could be reproduced only at cell densities that far exceeded those of ammonia oxidizers in the ocean. The presence of excess NO2− (up to 1 mM) in the growth medium also increased N2O yields by an average of 70% to 87% depending on O2 concentration. We made stable isotopic measurements on N2O from these cultures to identify the biochemical mechanisms behind variations in N2O yield. Based on measurements of δ15Nbulk, site preference (SP = δ15Nα−δ15Nβ), and δ18O of N2O (δ18O-N2O), we estimate that nitrifier-denitrification produced between 11% and 26% of N2O from cultures grown under 20% O2 and 43% to 87% under 0.5% O2. We also demonstrate that a positive correlation between SP and δ18O-N2O is expected when nitrifying bacteria produce N2O. A positive relationship between SP and δ18O-N2O has been observed in environmental N2O datasets, but until now, explanations for the observation invoked only denitrification. Such interpretations may overestimate the role of heterotrophic denitrification and underestimate the role of ammonia oxidation in environmental N2O production.

Nitrous oxide production by lithotrophic ammonia-oxidizing bacteria and implications for engineered nitrogen-removal systems

2011 ◽  
Vol 39 (6) ◽  
pp. 1832-1837 ◽  
Author(s):  
Kartik Chandran ◽  
Lisa Y. Stein ◽  
Martin G. Klotz ◽  
Mark C.M. van Loosdrecht
Keyword(s):  
Nitrous Oxide ◽  
Nitrogen Removal ◽  
Ammonia Oxidation ◽  
Wastewater Treatment Plants ◽  
N2o Emissions ◽  
Ammonia Oxidizing Bacteria ◽  
N2o Production ◽  
Nitrogen Emissions ◽  
Greenhouse Gas Inventories ◽  
Nitrogen Concentrations

Chemolithoautotrophic AOB (ammonia-oxidizing bacteria) form a crucial component in microbial nitrogen cycling in both natural and engineered systems. Under specific conditions, including transitions from anoxic to oxic conditions and/or excessive ammonia loading, and the presence of high nitrite (NO2−) concentrations, these bacteria are also documented to produce nitric oxide (NO) and nitrous oxide (N2O) gases. Essentially, ammonia oxidation in the presence of non-limiting substrate concentrations (ammonia and O2) is associated with N2O production. An exceptional scenario that leads to such conditions is the periodical switch between anoxic and oxic conditions, which is rather common in engineered nitrogen-removal systems. In particular, the recovery from, rather than imposition of, anoxic conditions has been demonstrated to result in N2O production. However, applied engineering perspectives, so far, have largely ignored the contribution of nitrification to N2O emissions in greenhouse gas inventories from wastewater-treatment plants. Recent field-scale measurements have revealed that nitrification-related N2O emissions are generally far higher than emissions assigned to heterotrophic denitrification. In the present paper, the metabolic pathways, which could potentially contribute to NO and N2O production by AOB have been conceptually reconstructed under conditions especially relevant to engineered nitrogen-removal systems. Taken together, the reconstructed pathways, field- and laboratory-scale results suggest that engineering designs that achieve low effluent aqueous nitrogen concentrations also minimize gaseous nitrogen emissions.

Modelling the N2O Emissions in Municipal Wastewater Treatment Plants under Dynamic Conditions

10.29007/w6rq ◽  
2018 ◽  
Author(s):  
Theoni Massara ◽  
Borja Solis Duran ◽  
Albert Guisasola ◽  
Evina Katsou ◽  
Juan Antonio Baeza
Keyword(s):  
Wastewater Treatment ◽  
Municipal Wastewater ◽  
Wastewater Treatment Plants ◽  
Partial Nitrification ◽  
Biological Nutrient Removal ◽  
N2o Emissions ◽  
Ammonia Oxidizing Bacteria ◽  
N2o Production ◽  
Dynamic Conditions ◽  
Nitrifier Denitrification

Nitrous oxide (N2O), a greenhouse gas with a significant global warming potential, can be produced during the biological nutrient removal in wastewater treatment plants (WWTPs). N2O modelling under dynamic conditions is of vital importance for its mitigation. Following the activated sludge models (ASM) layout, an ASM-type model was developed considering three biological N2O production pathways for a municipal anaerobic/anoxic/aerobic (A2/O) WWTP performing chemical oxygen demand, nitrogen and phosphorus removal. Precisely, the N2O production pathways included were: nitrifier denitrification, hydroxylamine oxidation, and heterotrophic denitrification, with the first two linked to the ammonia oxidizing bacteria (AOB) activity. A stripping effectivity (SE) factor was used to mark the non-ideality of the stripping modelling. With the dissolved oxygen (DO) in the aerobic compartment ranging from 1.8 to 2.5 mg L-1, partial nitrification and high N2O production via nitrifier denitrification occurred. Therefore, low aeration strategies can effectively lead to a low overall carbon footprint only if complete nitrification is guaranteed. After suddenly increasing the influent ammonium load, the AOB had a greater growth compared to the NOB. N2O hotspot was again nitrifier denitrification. Especially under concurring partial nitrification and high stripping (i.e. combination of low DO and high SEs), the highest N2O emission factors were noted.

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