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 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 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 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 Response to Comment on “Oxygen Regulates Nitrous Oxide Production Directly in Agricultural Soils”

2020 ◽  
Vol 54 (4) ◽  
pp. 2556-2557
Author(s):  
Xiaotong Song ◽  
Xiaotang Ju ◽  
Cairistiona F.E. Topp ◽  
Robert M. Rees
Keyword(s):  
Nitrous Oxide ◽  
Agricultural Soils ◽  
Oxide Production ◽  
Nitrous Oxide Production

REVIEW OF CHEMICAL REACTIONS IN THE NO REDUCTION BY CO ON PLATINUM/ALUMINA CATALYSTS

2012 ◽  
Vol 19 (01) ◽  
pp. 1230001 ◽  
Author(s):  
ANAND SRINIVASAN ◽  
CHRISTOPHER DEPCIK
Keyword(s):  
Nitric Oxide ◽  
Carbon Monoxide ◽  
Nitrous Oxide ◽  
Internal Combustion Engines ◽  
Catalytic Reduction ◽  
Platinum Group Metals ◽  
Combustion Engines ◽  
No Reduction By Co ◽  
Nitrous Oxide Production ◽  
Global Reaction

The emissions of nitric oxide and carbon monoxide from internal combustion engines generate a large impact on the environment and on people's health. Catalytic reduction of these species using platinum group metals has already shown significant potential for emissions control. Since catalysts often use carbon monoxide to reduce nitric oxide in these devices, accurate models of their interaction are required to advance catalyst simulations in order to meet increasingly stringent emissions regulations. As a result, this paper reviews the literature of the NO–CO reaction over platinum in order to develop more precise detailed and global reaction mechanisms for use in exhaust after-treatment modeling activities. Moreover, it is found that the reaction between NO and CO over platinum yields carbon dioxide and nitrogen as main products and nitrous oxide as an important side product. Hence, this paper additionally describes the mechanism for nitrous oxide production in advance of greenhouse gas regulations.

scholarly journals Nitrite Reductase of Nitrosomonas europaea Is Not Essential for Production of Gaseous Nitrogen Oxides and Confers Tolerance to Nitrite

2002 ◽  
Vol 184 (9) ◽  
pp. 2557-2560 ◽  
Author(s):  
Hubertus J. E. Beaumont ◽  
Norman G. Hommes ◽  
Luis A. Sayavedra-Soto ◽  
Daniel J. Arp ◽  
David M. Arciero ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Nitrous Oxide ◽  
Nitrogen Oxides ◽  
Nitrite Reductase ◽  
Nitrosomonas Europaea ◽  
Wild Type ◽  
Gaseous Nitrogen ◽  
Cell Extracts

ABSTRACT A gene that encodes a periplasmic copper-type nitrite reductase (NirK) was identified in Nitrosomonas europaea. Disruption of this gene resulted in the disappearance of Nir activity in cell extracts. The nitrite tolerance of NirK-deficient cells was lower than that of wild-type cells. Unexpectedly, NirK-deficient cells still produced nitric oxide (NO) and nitrous oxide (N2O), the latter in greater amounts than that of wild-type cells. This demonstrates that NirK is not essential for the production of NO and N2O by N. europaea. Inactivation of the putative fnr gene showed that Fnr is not essential for the expression of nirK.

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