Sample records for aerobic ammonia oxidation

  1. Aerobic cometabolic degradation of trichloroethene by methane and ammonia oxidizing microorganisms naturally associated with Carex comosa roots.

    PubMed

    Powell, C L; Nogaro, G; Agrawal, A

    2011-06-01

    The degradation potential of trichloroethene by the aerobic methane- and ammonia-oxidizing microorganisms naturally associated with wetland plant (Carex comosa) roots was examined in this study. In bench-scale microcosm experiments with washed (soil free) Carex comosa roots, the activity of root-associated methane- and ammonia-oxidizing microorganisms, which were naturally present on the root surface and/or embedded within the roots, was investigated. Significant methane and ammonia oxidation were observed reproducibly in batch reactors with washed roots incubated in growth media, where methane oxidation developed faster (2 weeks) compared to ammonia oxidation (4 weeks) in live microcosms. After enrichment, the methane oxidizers demonstrated their ability to degrade 150 μg l(-1) TCE effectively at 1.9 mg l(-1) of aqueous CH(4). In contrast, ammonia oxidizers showed a rapid and complete inhibition of ammonia oxidation with 150 μg l(-1) TCE at 20 mg l(-1) of NH(4)(+)-N, which may be attributed to greater sensitivity of ammonia oxidizers to TCE or its degradation product. No such inhibitory effect of TCE degradation was detected on methane oxidation at the above experimental conditions. The results presented here suggest that microorganisms associated with wetland plant roots can assist in the natural attenuation of TCE in contaminated aquatic environments.

  2. Factors Driving Potential Ammonia Oxidation in Canadian Arctic Ecosystems: Does Spatial Scale Matter?

    PubMed Central

    Banerjee, Samiran

    2012-01-01

    Ammonia oxidation is a major process in nitrogen cycling, and it plays a key role in nitrogen limited soil ecosystems such as those in the arctic. Although mm-scale spatial dependency of ammonia oxidizers has been investigated, little is known about the field-scale spatial dependency of aerobic ammonia oxidation processes and ammonia-oxidizing archaeal and bacterial communities, particularly in arctic soils. The purpose of this study was to explore the drivers of ammonia oxidation at the field scale in cryosols (soils with permafrost within 1 m of the surface). We measured aerobic ammonia oxidation potential (both autotrophic and heterotrophic) and functional gene abundance (bacterial amoA and archaeal amoA) in 279 soil samples collected from three arctic ecosystems. The variability associated with quantifying genes was substantially less than the spatial variability observed in these soils, suggesting that molecular methods can be used reliably evaluate spatial dependency in arctic ecosystems. Ammonia-oxidizing archaeal and bacterial communities and aerobic ammonia oxidation were spatially autocorrelated. Gene abundances were spatially structured within 4 m, whereas biochemical processes were structured within 40 m. Ammonia oxidation was driven at small scales (<1m) by moisture and total organic carbon, whereas gene abundance and other edaphic factors drove ammonia oxidation at medium (1 to 10 m) and large (10 to 100 m) scales. In these arctic soils heterotrophs contributed between 29 and 47% of total ammonia oxidation potential. The spatial scale for aerobic ammonia oxidation genes differed from potential ammonia oxidation, suggesting that in arctic ecosystems edaphic, rather than genetic, factors are an important control on ammonia oxidation. PMID:22081570

  3. The history of aerobic ammonia oxidizers: from the first discoveries to today.

    PubMed

    Monteiro, Maria; Séneca, Joana; Magalhães, Catarina

    2014-07-01

    Nitrification, the oxidation of ammonia to nitrite and nitrate, has long been considered a central biological process in the global nitrogen cycle, with its first description dated 133 years ago. Until 2005, bacteria were considered the only organisms capable of nitrification. However, the recent discovery of a chemoautotrophic ammonia-oxidizing archaeon, Nitrosopumilus maritimus, changed our concept of the range of organisms involved in nitrification, highlighting the importance of ammonia-oxidizing archaea (AOA) as potential players in global biogeochemical nitrogen transformations. The uniqueness of these archaea justified the creation of a novel archaeal phylum, Thaumarchaeota. These recent discoveries increased the global scientific interest within the microbial ecology society and have triggered an analysis of the importance of bacterial vs archaeal ammonia oxidation in a wide range of natural ecosystems. In this mini review we provide a chronological perspective of the current knowledge on the ammonia oxidation pathway of nitrification, based on the main physiological, ecological and genomic discoveries.

  4. Communities of ammonia-oxidizing bacteria in activated sludge of various sewage treatment plants in Tokyo.

    PubMed

    Limpiyakorn, Tawan; Shinohara, Yuko; Kurisu, Futoshi; Yagi, Osami

    2005-10-01

    We investigated ammonia-oxidizing bacteria in activated sludge collected from 12 sewage treatment systems, whose ammonia removal and treatment processes differed, during three different seasons. We used real-time PCR quantification to reveal total bacterial numbers and total ammonia oxidizer numbers, and used specific PCR followed by denaturing gel gradient electrophoresis, cloning, and sequencing of 16S rRNA genes to analyze ammonia-oxidizing bacterial communities. Total bacterial numbers and total ammonia oxidizer numbers were in the range of 1.6 x 10(12) - 2.4 x 10(13) and 1.0 x 10(9) - 9.2 x 10(10)cellsl(-1), respectively. Seasonal variation was observed in the total ammonia oxidizer numbers, but not in the ammonia-oxidizing bacterial communities. Members of the Nitrosomonas oligotropha cluster were found in all samples, and most sequences within this cluster grouped within two of the four sequence types identified. Members of the clusters of Nitrosomonas europaea-Nitrosococcus mobilis, Nitrosomonas cryotolerans, and unknown Nitrosomonas, occurred solely in one anaerobic/anoxic/aerobic (A2O) system. Members of the Nitrosomonas communis cluster occurred almost exclusively in association with A2O and anaerobic/aerobic systems. Solid residence time mainly influenced the total numbers of ammonia-oxidizing bacteria, whereas dissolved oxygen concentration primarily affected the ammonia-oxidizing activity per ammonia oxidizer cell.

  5. The transformation from anammox granules to deammonification granules in micro-aerobic system by facilitating indigenous ammonia oxidizing bacteria.

    PubMed

    Wang, Xiaolong; Gao, Dawen

    2018-02-01

    Granular deammonification process is a good way to retain aerobic and anaerobic ammonia oxidizing bacteria (AOB and anammox bacteria) and exhaust flocculent nitrite oxidizing bacteria (NOB). In this study, to facilitate indigenous AOB growth on anammox granules, by stepwise reducing influent nitrite, anammox granules were effectively transformed into deammonification granules in a micro-aerobic EGSB in 100 days. Total nitrogen removal efficiency of 90% and nitrogen removal rate of 2.3 g N/L/d were reached at stable deammonification stage. High influent FA and limited oxygen supply contributed suppression for Nitrospira-like NOB. In transition stages, Proteobacteria and Chloroflexi were always dominated. Anammox abundance decreased, while AOB abundance grew fast. Anammox bacteria and AOB were dominated by Brocadia fulgida and Nitrosomonas europaea, respectively. Denitrification activity and bacteria existed although without influent organic. The final AOB abundance was about 4.55-13.8 times more than anammox bacteria abundance, with almost equal potential activities. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Ammonia removal in electrochemical oxidation: mechanism and pseudo-kinetics.

    PubMed

    Li, Liang; Liu, Yan

    2009-01-30

    This paper investigated the mechanism and pseudo-kinetics for removal of ammonia by electrochemical oxidation with RuO(2)/Ti anode using batch tests. The results show that the ammonia oxidation rates resulted from direct oxidation at electrode-liquid interfaces of the anode by stepwise dehydrogenation, and from indirect oxidation by hydroxyl radicals were so slow that their contribution to ammonia removal was negligible under the condition with Cl(-). The oxidation rates of ammonia ranged from 1.0 to 12.3 mg N L(-1)h(-1) and efficiency reached nearly 100%, primarily due to the indirect oxidation of HOCl, and followed pseudo zero-order kinetics in electrochemical oxidation with Cl(-). About 88% ammonia was removed from the solution. The removed one was subsequently found in the form of N(2) in the produced gas. The rate at which Cl(-) lost electrons at the anode was a major factor in the overall ammonia oxidation. Current density and Cl(-) concentration affected the constant of the pseudo zero-order kinetics, expressed by k=0.0024[Cl(-)]xj. The ammonia was reduced to less than 0.5 mg N L(-1) after 2h of electrochemical oxidation for the effluent from aerobic or anaerobic reactors which treated municipal wastewater. This result was in line with the strict discharge requirements.

  7. Ammonia transformations and abundance of ammonia oxidizers in a clay soil underlying a manure pond.

    PubMed

    Sher, Yonatan; Baram, Shahar; Dahan, Ofer; Ronen, Zeev; Nejidat, Ali

    2012-07-01

    Unlined manure ponds are constructed on clay soil worldwide to manage farm waste. Seepage of ammonia-rich liquor into underlying soil layers contributes to groundwater contamination by nitrate. To identify the possible processes that lead to the production of nitrate from ammonia in this oxygen-limited environment, we studied the diversity and abundance of ammonia-transforming microorganisms under an unlined manure pond. The numbers of ammonia-oxidizing bacteria and anammox bacteria were most abundant in the top of the soil profile and decreased significantly with depth (0.5 m), correlating with soil pore-water ammonia concentrations and soil ammonia concentrations, respectively. On the other hand, the numbers of ammonia-oxidizing archaea were relatively constant throughout the soil profile (10(7) amoA copies per g(soil)). Nitrite-oxidizing bacteria were detected mainly in the top 0.2 m. The results suggest that nitrate accumulation in the vadose zone under the manure pond could be the result of complete aerobic nitrification (ammonia oxidation to nitrate) and could exist as a byproduct of anammox activity. While the majority of the nitrogen was removed within the 0.5-m soil section, possibly by combined anammox and heterotrophic denitrification, a fraction of the produced nitrate leached into the groundwater. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  8. Diversity, Physiology, and Niche Differentiation of Ammonia-Oxidizing Archaea

    PubMed Central

    2012-01-01

    Nitrification, the aerobic oxidation of ammonia to nitrate via nitrite, has been suggested to have been a central part of the global biogeochemical nitrogen cycle since the oxygenation of Earth. The cultivation of several ammonia-oxidizing archaea (AOA) as well as the discovery that archaeal ammonia monooxygenase (amo)-like gene sequences are nearly ubiquitously distributed in the environment and outnumber their bacterial counterparts in many habitats fundamentally revised our understanding of nitrification. Surprising insights into the physiological distinctiveness of AOA are mirrored by the recognition of the phylogenetic uniqueness of these microbes, which fall within a novel archaeal phylum now known as Thaumarchaeota. The relative importance of AOA in nitrification, compared to ammonia-oxidizing bacteria (AOB), is still under debate. This minireview provides a synopsis of our current knowledge of the diversity and physiology of AOA, the factors controlling their ecology, and their role in carbon cycling as well as their potential involvement in the production of the greenhouse gas nitrous oxide. It emphasizes the importance of activity-based analyses in AOA studies and formulates priorities for future research. PMID:22923400

  9. Influence of oxic/anoxic fluctuations on ammonia oxidizers and nitrification potential in a wet tropical soil.

    PubMed

    Pett-Ridge, Jennifer; Petersen, Dorthe G; Nuccio, Erin; Firestone, Mary K

    2013-07-01

    Ammonia oxidation is a key process in the global nitrogen cycle. However, in tropical soils, little is known about ammonia-oxidizing microorganisms and how characteristically variable oxygen regimes affect their activity. We investigated the influence of brief anaerobic periods on ammonia oxidation along an elevation, moisture, and oxygen availability gradient in wet tropical soils. Soils from three forest types were incubated for up to 36 weeks in lab microcosms under three regimes: (1) static aerobic; (2) static anaerobic; and (3) fluctuating (aerobic/anaerobic). Nitrification potential was measured in field-fresh soils and incubated soils. The native ammonia-oxidizing community was also characterized, based on diversity assessments (clone libraries) and quantification of the ammonia monooxygenase α-subunit (amoA) gene. These relatively low pH soils appear to be dominated by ammonia-oxidizing archaea (AOA), and AOA communities in the three soil types differed significantly in their ability to oxidize ammonia. Soils from an intermediate elevation, and those incubated with fluctuating redox conditions, tended to have the highest nitrification potential following an influx of oxygen, although all soils retained the capacity to nitrify even after long anoxic periods. Together, these results suggest that wet tropical soil AOA are tolerant of extended periods of anoxia. © 2013 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  10. Archaea produce lower yields of N2 O than bacteria during aerobic ammonia oxidation in soil.

    PubMed

    Hink, Linda; Nicol, Graeme W; Prosser, James I

    2017-12-01

    Nitrogen fertilisation of agricultural soil contributes significantly to emissions of the potent greenhouse gas nitrous oxide (N 2 O), which is generated during denitrification and, in oxic soils, mainly by ammonia oxidisers. Although laboratory cultures of ammonia oxidising bacteria (AOB) and archaea (AOA) produce N 2 O, their relative activities in soil are unknown. This work tested the hypothesis that AOB dominate ammonia oxidation and N 2 O production under conditions of high inorganic ammonia (NH 3 ) input, but result mainly from the activity of AOA when NH 3 is derived from mineralisation. 1-octyne, a recently discovered inhibitor of AOB, was used to distinguish N 2 O production resulting from archaeal and bacterial ammonia oxidation in soil microcosms, and specifically inhibited AOB growth, activity and N 2 O production. In unamended soils, ammonia oxidation and N 2 O production were lower and resulted mainly from ammonia oxidation by AOA. The AOA N 2 O yield relative to nitrite produced was half that of AOB, likely due to additional enzymatic mechanisms in the latter, but ammonia oxidation and N 2 O production were directly linked in all treatments. Relative contributions of AOA and AOB to N 2 O production, therefore, reflect their respective contributions to ammonia oxidation. These results suggest potential mitigation strategies for N 2 O emissions from fertilised agricultural soils. © 2016 The Authors. Environmental Microbiology published by Society for Applied Microbiology and John Wiley & Sons Ltd.

  11. Nitric oxide scavengers differentially inhibit ammonia oxidation in ammonia-oxidizing archaea and bacteria.

    PubMed

    Sauder, Laura A; Ross, Ashley A; Neufeld, Josh D

    2016-04-01

    Differential inhibitors are important for measuring the relative contributions of microbial groups, such as ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA), to biogeochemical processes in environmental samples. In particular, 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (PTIO) represents a nitric oxide scavenger used for the specific inhibition of AOA, implicating nitric oxide as an intermediate of thaumarchaeotal ammonia oxidation. This study investigated four alternative nitric oxide scavengers for their ability to differentially inhibit AOA and AOB in comparison to PTIO. Caffeic acid, curcumin, methylene blue hydrate and trolox were tested onNitrosopumilus maritimus, two unpublished AOA representatives (AOA-6f and AOA-G6) as well as the AOB representative Nitrosomonas europaea All four scavengers inhibited ammonia oxidation by AOA at lower concentrations than for AOB. In particular, differential inhibition of AOA and AOB by caffeic acid (100 μM) and methylene blue hydrate (3 μM) was comparable to carboxy-PTIO (100 μM) in pure and enrichment culture incubations. However, when added to aquarium sponge biofilm microcosms, both scavengers were unable to inhibit ammonia oxidation consistently, likely due to degradation of the inhibitors themselves. This study provides evidence that a variety of nitric oxide scavengers result in differential inhibition of ammonia oxidation in AOA and AOB, and provides support to the proposed role of nitric oxide as a key intermediate in the thaumarchaeotal ammonia oxidation pathway. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  12. Simultaneous effect of temperature, cyanide and ammonia-oxidizing bacteria concentrations on ammonia oxidation.

    PubMed

    Do, Hyojin; Lim, Juntaek; Shin, Seung Gu; Wu, Yi-Ju; Ahn, Johng-Hwa; Hwang, Seokhwan

    2008-11-01

    For biological nitrification, a set of experiments were carried out to approximate the response of lag period along with ammonia oxidation rate with respect to different concentrations of cyanide (CN-) and ammonia-oxidizing bacteria (AOB), and temperature variation in laboratory-scale batch reactors. The effects of simultaneous changes in these three factors on ammonia oxidation were quantitatively estimated and modeled using response surface analysis. The lag period and the ammonia oxidation rate responded differently to changes in the three factors. The lag period and the ammonia oxidation rate were significantly affected by the CN- and AOB concentrations, while temperature changes only affected the ammonia oxidation rate. The increase of AOB concentration and temperature alleviated the inhibition effect of cyanide on ammonia oxidation. The statistical method used in this study can be extended to estimate the quantitative effects of other environmental factors that can change simultaneously.

  13. Development of a simultaneous partial nitrification, anaerobic ammonia oxidation and denitrification (SNAD) bench scale process for removal of ammonia from effluent of a fertilizer industry.

    PubMed

    Keluskar, Radhika; Nerurkar, Anuradha; Desai, Anjana

    2013-02-01

    A simultaneous partial nitrification, anammox and denitrification (SNAD) process was developed for the treatment of ammonia laden effluent of a fertilizer industry. Autotrophic aerobic and anaerobic ammonia oxidizing biomass was enriched and their ammonia removal ability was confirmed in synthetic effluent system. Seed consortium developed from these was applied in the treatment of effluent in an oxygen limited bench scale SNAD type (1L) reactor run at ambient temperature (∼30°C). Around 98.9% ammonia removal was achieved with ammonia loading rate 0.35kgNH(4)(+)-N/m(3)day in the presence of 46.6mg/L COD at 2.31days hydraulic retention time. Qualitative and quantitative analysis of the biomass from upper and lower zone of the reactor revealed presence of autotrophic ammonia oxidizing bacteria (AOB), Planctomycetes and denitrifiers as the dominant bacteria carrying out anoxic oxidation of ammonia in the reactor. Physiological and molecular studies strongly indicate presence of anammox bacteria in the anoxic zone of the SNAD reactor. Copyright © 2012 Elsevier Ltd. All rights reserved.

  14. Differential contributions of ammonia oxidizers and nitrite oxidizers to nitrification in four paddy soils

    PubMed Central

    Wang, Baozhan; Zhao, Jun; Guo, Zhiying; Ma, Jing; Xu, Hua; Jia, Zhongjun

    2015-01-01

    Rice paddy fields are characterized by regular flooding and nitrogen fertilization, but the functional importance of aerobic ammonia oxidizers and nitrite oxidizers under unique agricultural management is poorly understood. In this study, we report the differential contributions of ammonia-oxidizing archaea (AOA), bacteria (AOB) and nitrite-oxidizing bacteria (NOB) to nitrification in four paddy soils from different geographic regions (Zi-Yang (ZY), Jiang-Du (JD), Lei-Zhou (LZ) and Jia-Xing (JX)) that are representative of the rice ecosystems in China. In urea-amended microcosms, nitrification activity varied greatly with 11.9, 9.46, 3.03 and 1.43 μg NO3−-N g−1 dry weight of soil per day in the ZY, JD, LZ and JX soils, respectively, over the course of a 56-day incubation period. Real-time quantitative PCR of amoA genes and pyrosequencing of 16S rRNA genes revealed significant increases in the AOA population to various extents, suggesting that their relative contributions to ammonia oxidation activity decreased from ZY to JD to LZ. The opposite trend was observed for AOB, and the JX soil stimulated only the AOB populations. DNA-based stable-isotope probing further demonstrated that active AOA numerically outcompeted their bacterial counterparts by 37.0-, 10.5- and 1.91-fold in 13C-DNA from ZY, JD and LZ soils, respectively, whereas AOB, but not AOA, were labeled in the JX soil during active nitrification. NOB were labeled to a much greater extent than AOA and AOB, and the addition of acetylene completely abolished the assimilation of 13CO2 by nitrifying populations. Phylogenetic analysis suggested that archaeal ammonia oxidation was predominantly catalyzed by soil fosmid 29i4-related AOA within the soil group 1.1b lineage. Nitrosospira cluster 3-like AOB performed most bacterial ammonia oxidation in the ZY, LZ and JX soils, whereas the majority of the 13C-AOB in the JD soil was affiliated with the Nitrosomona communis lineage. The 13C-NOB was overwhelmingly

  15. Differential contributions of ammonia oxidizers and nitrite oxidizers to nitrification in four paddy soils.

    PubMed

    Wang, Baozhan; Zhao, Jun; Guo, Zhiying; Ma, Jing; Xu, Hua; Jia, Zhongjun

    2015-05-01

    Rice paddy fields are characterized by regular flooding and nitrogen fertilization, but the functional importance of aerobic ammonia oxidizers and nitrite oxidizers under unique agricultural management is poorly understood. In this study, we report the differential contributions of ammonia-oxidizing archaea (AOA), bacteria (AOB) and nitrite-oxidizing bacteria (NOB) to nitrification in four paddy soils from different geographic regions (Zi-Yang (ZY), Jiang-Du (JD), Lei-Zhou (LZ) and Jia-Xing (JX)) that are representative of the rice ecosystems in China. In urea-amended microcosms, nitrification activity varied greatly with 11.9, 9.46, 3.03 and 1.43 μg NO3(-)-N g(-1) dry weight of soil per day in the ZY, JD, LZ and JX soils, respectively, over the course of a 56-day incubation period. Real-time quantitative PCR of amoA genes and pyrosequencing of 16S rRNA genes revealed significant increases in the AOA population to various extents, suggesting that their relative contributions to ammonia oxidation activity decreased from ZY to JD to LZ. The opposite trend was observed for AOB, and the JX soil stimulated only the AOB populations. DNA-based stable-isotope probing further demonstrated that active AOA numerically outcompeted their bacterial counterparts by 37.0-, 10.5- and 1.91-fold in (13)C-DNA from ZY, JD and LZ soils, respectively, whereas AOB, but not AOA, were labeled in the JX soil during active nitrification. NOB were labeled to a much greater extent than AOA and AOB, and the addition of acetylene completely abolished the assimilation of (13)CO2 by nitrifying populations. Phylogenetic analysis suggested that archaeal ammonia oxidation was predominantly catalyzed by soil fosmid 29i4-related AOA within the soil group 1.1b lineage. Nitrosospira cluster 3-like AOB performed most bacterial ammonia oxidation in the ZY, LZ and JX soils, whereas the majority of the (13)C-AOB in the JD soil was affiliated with the Nitrosomona communis lineage. The (13)C-NOB was

  16. Aerobic nitrous oxide production through N-nitrosating hybrid formation in ammonia-oxidizing archaea.

    PubMed

    Stieglmeier, Michaela; Mooshammer, Maria; Kitzler, Barbara; Wanek, Wolfgang; Zechmeister-Boltenstern, Sophie; Richter, Andreas; Schleper, Christa

    2014-05-01

    Soil emissions are largely responsible for the increase of the potent greenhouse gas nitrous oxide (N2O) in the atmosphere and are generally attributed to the activity of nitrifying and denitrifying bacteria. However, the contribution of the recently discovered ammonia-oxidizing archaea (AOA) to N2O production from soil is unclear as is the mechanism by which they produce it. Here we investigate the potential of Nitrososphaera viennensis, the first pure culture of AOA from soil, to produce N2O and compare its activity with that of a marine AOA and an ammonia-oxidizing bacterium (AOB) from soil. N. viennensis produced N2O at a maximum yield of 0.09% N2O per molecule of nitrite under oxic growth conditions. N2O production rates of 4.6±0.6 amol N2O cell(-1) h(-1) and nitrification rates of 2.6±0.5 fmol NO2(-) cell(-1) h(-1) were in the same range as those of the AOB Nitrosospira multiformis and the marine AOA Nitrosopumilus maritimus grown under comparable conditions. In contrast to AOB, however, N2O production of the two archaeal strains did not increase when the oxygen concentration was reduced, suggesting that they are not capable of denitrification. In (15)N-labeling experiments we provide evidence that both ammonium and nitrite contribute equally via hybrid N2O formation to the N2O produced by N. viennensis under all conditions tested. Our results suggest that archaea may contribute to N2O production in terrestrial ecosystems, however, they are not capable of nitrifier-denitrification and thus do not produce increasing amounts of the greenhouse gas when oxygen becomes limiting.

  17. Autotrophic ammonia oxidation by soil thaumarchaea.

    PubMed

    Zhang, Li-Mei; Offre, Pierre R; He, Ji-Zheng; Verhamme, Daniel T; Nicol, Graeme W; Prosser, James I

    2010-10-05

    Nitrification plays a central role in the global nitrogen cycle and is responsible for significant losses of nitrogen fertilizer, atmospheric pollution by the greenhouse gas nitrous oxide, and nitrate pollution of groundwaters. Ammonia oxidation, the first step in nitrification, was thought to be performed by autotrophic bacteria until the recent discovery of archaeal ammonia oxidizers. Autotrophic archaeal ammonia oxidizers have been cultivated from marine and thermal spring environments, but the relative importance of bacteria and archaea in soil nitrification is unclear and it is believed that soil archaeal ammonia oxidizers may use organic carbon, rather than growing autotrophically. In this soil microcosm study, stable isotope probing was used to demonstrate incorporation of (13)C-enriched carbon dioxide into the genomes of thaumarchaea possessing two functional genes: amoA, encoding a subunit of ammonia monooxygenase that catalyses the first step in ammonia oxidation; and hcd, a key gene in the autotrophic 3-hydroxypropionate/4-hydroxybutyrate cycle, which has been found so far only in archaea. Nitrification was accompanied by increases in archaeal amoA gene abundance and changes in amoA gene diversity, but no change was observed in bacterial amoA genes. Archaeal, but not bacterial, amoA genes were also detected in (13)C-labeled DNA, demonstrating inorganic CO(2) fixation by archaeal, but not bacterial, ammonia oxidizers. Autotrophic archaeal ammonia oxidation was further supported by coordinate increases in amoA and hcd gene abundance in (13)C-labeled DNA. The results therefore provide direct evidence for a role for archaea in soil ammonia oxidation and demonstrate autotrophic growth of ammonia oxidizing archaea in soil.

  18. Oxidation of ammonia and methane in an alkaline, saline lake

    USGS Publications Warehouse

    Joye, S.B.; Connell, T.L.; Miller, L.G.; Oremland, R.S.; Jellison, R.S.

    1999-01-01

    The oxidation of ammonia (NH3) and methane (CH4) was investigated in an alkaline saline lake, Mono Lake, California (U.S.A.). Ammonia oxidation was examined in April and July 1995 by comparing dark 14CO2 fixation rates in the presence or absence of methyl fluoride (MeF), an inhibitor of NH3 oxidation. Ammonia oxidizer-mediated dark 14CO2 fixation rates were similar in surface (5-7 m) and oxycline (11-15 m) waters, ranging between 70-340 and 89-186 nM d-1, respectively, or 1-7% of primary production by phytoplankton. Ammonia oxidation rates ranged between 580-2,830 nM d-1 in surface waters and 732-1,548 nM d-1 in oxycline waters. Methane oxidation was examined using a 14CH4 tracer technique in July 1994, April 1995, and July 1995. Methane oxidation rates were consistently higher in July, and rates in oxycline and anaerobic bottom waters (0.5-37 and 7-48 nM d-1, respectively) were 10-fold higher than those in aerobic surface waters (0.04-3.8 nM d-1). The majority of CH4 oxidation, in terms of integrated activity, occurred within anoxic bottom waters. Water column oxidation reduced the potential lake-atmosphere CH4 flux by a factor of two to three. Measured oxidation rates and water column concentrations were used to estimate the biological turnover times of NH3 and CH4. The NH3 pool turns over rapidly, on time scales of 0.8 d in surface waters and 10 d within the oxycline, while CH4 is cycled on 103-d time scales in surface waters and 102-d time scales within oxycline and bottom waters. Our data suggest an important role for NH3 oxidation in alkaline, saline lakes since the process converts volatile NH3 to soluble NO2-, thereby reducing loss via lake-atmosphere exchange and maintaining nitrogen in a form that is readily available to phytoplankton.

  19. Metabolism of Nitrogen Oxides in Ammonia-Oxidizing Bacteria

    NASA Astrophysics Data System (ADS)

    Kozlowski, J.; Stein, L. Y.

    2014-12-01

    Ammonia-oxidizing bacteria (AOB) are key microorganisms in the transformation of nitrogen intermediates in most all environments. Until recently there was very little work done to elucidate the physiology of ammonia-oxidizing bacteria cultivated from variable trophic state environments. With a greater variety of ammonia-oxidizers now in pure culture the importance of comparative physiological and genomic analysis is crucial. Nearly all known physiology of ammonia-oxidizing bacteria lies within the Nitrosomonas genus with Nitrosomonas europaea strain ATCC 19718 as the model. To more broadly characterize and understand the nature of obligate ammonia chemolithotrophy and the contribution of AOB to production of nitrogen oxides, Nitrosomonas spp. and Nitrosospira spp. isolated from variable trophic states and with sequenced genomes, were utilized. Instantaneous ammonia- and hydroxylamine-oxidation kinetics as a function of oxygen and substrate concentration were measured using an oxygen micro-sensor. The pathway intermediates nitric oxide and nitrous oxide were measured in real time using substrate-specific micro-sensors to elucidate whether production of these molecules is stoichiometric with rates of substrate oxidation. Genomic inventory was compared among the strains to identify specific pathways and modules to explain physiological differences in kinetic rates and production of N-oxide intermediates as a condition of their adaptation to different ammonium concentrations. This work provides knowledge of how nitrogen metabolism is differentially controlled in AOB that are adapted to different concentrations of ammonium. Overall, this work will provide further insight into the control of ammonia oxidizing chemolithotrophy across representatives of the Nitrosomonas and Nitrosospira genus, which can then be applied to examine additional genome-sequenced AOB isolates.

  20. Ammonia-oxidizing archaea have more important role than ammonia-oxidizing bacteria in ammonia oxidation of strongly acidic soils

    PubMed Central

    Zhang, Li-Mei; Hu, Hang-Wei; Shen, Ju-Pei; He, Ji-Zheng

    2012-01-01

    Increasing evidence demonstrated the involvement of ammonia-oxidizing archaea (AOA) in the global nitrogen cycle, but the relative contributions of AOA and ammonia-oxidizing bacteria (AOB) to ammonia oxidation are still in debate. Previous studies suggest that AOA would be more adapted to ammonia-limited oligotrophic conditions, which seems to be favored by protonation of ammonia, turning into ammonium in low-pH environments. Here, we investigated the autotrophic nitrification activity of AOA and AOB in five strongly acidic soils (pH<4.50) during microcosm incubation for 30 days. Significantly positive correlations between nitrate concentration and amoA gene abundance of AOA, but not of AOB, were observed during the active nitrification. 13CO2-DNA-stable isotope probing results showed significant assimilation of 13C-labeled carbon source into the amoA gene of AOA, but not of AOB, in one of the selected soil samples. High levels of thaumarchaeal amoA gene abundance were observed during the active nitrification, coupled with increasing intensity of two denaturing gradient gel electrophoresis bands for specific thaumarchaeal community. Addition of the nitrification inhibitor dicyandiamide (DCD) completely inhibited the nitrification activity and CO2 fixation by AOA, accompanied by decreasing thaumarchaeal amoA gene abundance. Bacterial amoA gene abundance decreased in all microcosms irrespective of DCD addition, and mostly showed no correlation with nitrate concentrations. Phylogenetic analysis of thaumarchaeal amoA gene and 16S rRNA gene revealed active 13CO2-labeled AOA belonged to groups 1.1a-associated and 1.1b. Taken together, these results provided strong evidence that AOA have a more important role than AOB in autotrophic ammonia oxidation in strongly acidic soils. PMID:22134644

  1. Enhanced generation of perfluoroalkyl carboxylic acids (PFCAs) from fluorotelomer alcohols (FTOHs) via ammonia-oxidation process.

    PubMed

    Yu, Xiaolong; Nishimura, Fumitake; Hidaka, Taira

    2018-05-01

    With the phase-out of persistent, bioaccumalative, and toxic perfluoroalkyl carboxylic acids (PFCAs), it is needed to explore the potential release of PFCAs from precursors being emitted into the environment. Biotransformation of fluorotelomer alcohols (FTOHs) via biological processes in wastewater treatment plants (WWTPs) leads to discharge of PFCAs into receiving waters. However, the commonly existed microbial activity that can impact on FTOHs biodegradation in WWTPs remains unclear. The objective of present research was to explore the relationship between ammonia-oxidation process and the enhanced PFCAs generation from FTOHs biodegradation under aerobic activated sludge. The obtained results indicate that the cometabolism process performed by nitrifying microorganisms (NMs) was responsible for enhanced PFCAs generation. Among NMs, the ammonia-oxidation bacteria that can express non-specific enzyme of ammonia monooxygenases resulted in the enhanced PFCAs generation from FTOHs. Meanwhile, the different addition amount of ammonia contributed to different defluorination efficiency of FTOHs. The present study further correlated the enhanced PFCAs generation from FTOHs biodegradation with ammonia-oxidation process, which can provide practical information on effective management of PFCAs generation in WWTPs. Copyright © 2018 Elsevier Ltd. All rights reserved.

  2. [Microbial ecology of archaeal ammonia oxidation--a review].

    PubMed

    Jia, Zhongjun; Weng, Jiahua; Lin, Xiangui; Conrad, Ralf

    2010-04-01

    Bacteria have long been considered as the key driver of ammonia oxidation on earth. This concept has been challenged recently by the discovery of chemolithoautotrophic isolate of ammonia-oxidizing archaeon in marine. The relative contribution of bacteria and archaea to ammonia oxidation is essential for our understanding of global nitrogen cycle. Recent study suggested a key role of archaeal ammonia oxidation in the marine nitrogen cycle. Our work however revealed the predominace of bacterial ammonia oxidation in agricultural soil. From the biogeochemical perspective, here we summarized the discovery, progress and prospect of archaeal ammonia oxidation. Of great interest in the future would be to elucidate the metabolisms of ammonia-oxidizing archaeon in natural environment and the underlying mechanism that leads to the physiological divergence of ammonia oxidizers.

  3. Cultivation and Genomic Analysis of “Candidatus Nitrosocaldus islandicus,” an Obligately Thermophilic, Ammonia-Oxidizing Thaumarchaeon from a Hot Spring Biofilm in Graendalur Valley, Iceland

    PubMed Central

    Daebeler, Anne; Herbold, Craig W.; Vierheilig, Julia; Sedlacek, Christopher J.; Pjevac, Petra; Albertsen, Mads; Kirkegaard, Rasmus H.; de la Torre, José R.; Daims, Holger; Wagner, Michael

    2018-01-01

    Ammonia-oxidizing archaea (AOA) within the phylum Thaumarchaeota are the only known aerobic ammonia oxidizers in geothermal environments. Although molecular data indicate the presence of phylogenetically diverse AOA from the Nitrosocaldus clade, group 1.1b and group 1.1a Thaumarchaeota in terrestrial high-temperature habitats, only one§ enrichment culture of an AOA thriving above 50°C has been reported and functionally analyzed. In this study, we physiologically and genomically characterized a newly discovered thaumarchaeon from the deep-branching Nitrosocaldaceae family of which we have obtained a high (∼85%) enrichment from biofilm of an Icelandic hot spring (73°C). This AOA, which we provisionally refer to as “Candidatus Nitrosocaldus islandicus,” is an obligately thermophilic, aerobic chemolithoautotrophic ammonia oxidizer, which stoichiometrically converts ammonia to nitrite at temperatures between 50 and 70°C. “Ca. N. islandicus” encodes the expected repertoire of enzymes proposed to be required for archaeal ammonia oxidation, but unexpectedly lacks a nirK gene and also possesses no identifiable other enzyme for nitric oxide (NO) generation§. Nevertheless, ammonia oxidation by this AOA appears to be NO-dependent as “Ca. N. islandicus” is, like all other tested AOA, inhibited by the addition of an NO scavenger. Furthermore, comparative genomics revealed that “Ca. N. islandicus” has the potential for aromatic amino acid fermentation as its genome encodes an indolepyruvate oxidoreductase (iorAB) as well as a type 3b hydrogenase, which are not present in any other sequenced AOA. A further surprising genomic feature of this thermophilic ammonia oxidizer is the absence of DNA polymerase D genes§ – one of the predominant replicative DNA polymerases in all other ammonia-oxidizing Thaumarchaeota. Collectively, our findings suggest that metabolic versatility and DNA replication might differ substantially between obligately thermophilic and

  4. Transcriptional Response of the Archaeal Ammonia Oxidizer Nitrosopumilus maritimus to Low and Environmentally Relevant Ammonia Concentrations

    PubMed Central

    Stahl, David A.

    2013-01-01

    The ability of chemoautotrophic ammonia-oxidizing archaea to compete for ammonia among marine microorganisms at low ambient concentrations has been in part attributed to their extremely high affinity for ammonia, but as yet there is no mechanistic understanding of supporting metabolism. We examined transcription of selected genes for anabolic functions (CO2 fixation, ammonia transport, and cell wall synthesis) and a central catabolic function (ammonia oxidation) in the thaumarchaeon Nitrosopumilus maritimus SCM1 growing at two ammonia concentrations, as measured by combined ammonia and ammonium, one well above the Km for ammonia oxidation (∼500 μM) and the other well below the Km (<10 nM). Transcript levels were generally immediately and differentially repressed when cells transitioned from ammonia-replete to ammonia-limiting conditions. Transcript levels for ammonia oxidation, CO2 fixation, and one of the ammonia transport genes were approximately the same at high and low ammonia availability. Transcripts for all analyzed genes decreased with time in the complete absence of ammonia, but with various rates of decay. The new steady-state mRNA levels established are presumably more reflective of the natural physiological state of ammonia-oxidizing archaea and offer a reference for interpreting message abundance patterns in the natural environment. PMID:23995944

  5. Sanitising black water by auto-thermal aerobic digestion (ATAD) combined with ammonia treatment.

    PubMed

    Nordin, Annika C; Vinnerås, Björn

    2015-01-01

    The effect of a two-step process on the concentration of pathogens and indicator microorganisms in black water (0.9-1% total solids) was studied. The treatment combined auto-thermal aerobic digestion (ATAD) and ammonia sanitisation. First, the temperature of the black water was increased through ATAD and when a targeted temperature was reached (33, 41 and 45.5 °C studied), urea was added to a 0.5% concentration (total ammonia nitrogen >2.9 g L⁻¹). Escherichia coli and Salmonella spp. were reduced to non-detectable levels within 3 days following urea addition at temperatures above 40 °C, whereas when urea was added at 33 °C E. coli was still present after 8 days. By adding urea at temperatures of 40 °C and above, a 5 log10 reduction in Enterococcus spp. and a 3 log10 reduction in Ascaris suum eggs was achieved 1 week after the addition. With combined ATAD and ammonia treatment using 0.5% ww urea added at an aerobic digestion temperature >40 °C, black water was sanitised regarding the pathogens studied in 2 weeks of total treatment time.

  6. Nitrate reductase and nitrous oxide production by Fusarium oxysporum 11dn1 under aerobic and anaerobic conditions.

    PubMed

    Kurakov, A V; Nosikov, A N; Skrynnikova, E V; L'vov, N P

    2000-08-01

    The fungus Fusarium oxysporum 11dn1 was found to be able to grow and produce nitrous oxide on nitrate-containing medium in anaerobic conditions. The rate of nitrous oxide formation was three to six orders of magnitude lower than the rates of molecular nitrogen production by common denitrifying bacteria. Acetylene and ammonia did not affect the release of nitrous oxide release. It was shown that under anaerobic conditions fast increase of nitrate reductase activity occurred, caused by the synthesis of enzyme de novo and protein dephosphorylation. Reverse transfer of the mycelium to aerobic conditions led to a decline in nitrate reductase activity and stopped nitrous oxide production. The presence of two nitrate reductases was shown, which differed in molecular mass, location, temperature optima, and activity in nitrate- and ammonium-containing media. Two enzymes represent assimilatory and dissimilatory nitrate reductases, which are active in aerobic and anaerobic conditions, respectively.

  7. Niche differentiation of ammonia oxidizers and nitrite oxidizers in rice paddy soil.

    PubMed

    Ke, Xiubin; Angel, Roey; Lu, Yahai; Conrad, Ralf

    2013-08-01

    The dynamics of populations and activities of ammonia-oxidizing and nitrite-oxidizing microorganisms were investigated in rice microcosms treated with two levels of nitrogen. Different soil compartments (surface, bulk, rhizospheric soil) and roots (young and old roots) were collected at three time points (the panicle initiation, heading and maturity periods) of the season. The population dynamics of bacterial (AOB) and archaeal (AOA) ammonia oxidizers was assayed by determining the abundance (using qPCR) and composition (using T-RFLP and cloning/sequencing) of their amoA genes (coding for a subunit of ammonia monooxygenase), that of nitrite oxidizers (NOB) by quantifying the nxrA gene (coding for a subunit of nitrite oxidase of Nitrobacter spp.) and the 16S rRNA gene of Nitrospira spp. The activity of the nitrifiers was determined by measuring the rates of potential ammonia oxidation and nitrite oxidation and by quantifying the copy numbers of amoA and nxrA transcripts. Potential nitrite oxidation activity was much higher than potential ammonia oxidation activity and was not directly affected by nitrogen amendment demonstrating the importance of ammonia oxidizers as pace makers for nitrite oxidizer populations. Marked differences in the distribution of bacterial and archaeal ammonia oxidizers, and of Nitrobacter-like and Nitrospira-like nitrite oxidizers were found in the different compartments of planted paddy soil indicating niche differentiation. In bulk soil, ammonia-oxidizing bacteria (Nitrosospira and Nitrosomonas) were at low abundance and displayed no activity, but in surface soil their activity and abundance was high. Nitrite oxidation in surface soil was dominated by Nitrospira spp. By contrast, ammonia-oxidizing Thaumarchaeota and Nitrobacter spp. seemed to dominate nitrification in rhizospheric soil and on rice roots. In contrast to soil compartment, the level of N fertilization and the time point of sampling had only little effect on the abundance

  8. Stimulation of thaumarchaeal ammonia oxidation by ammonia derived from organic nitrogen but not added inorganic nitrogen.

    PubMed

    Levičnik-Höfferle, Spela; Nicol, Graeme W; Ausec, Luka; Mandić-Mulec, Ines; Prosser, James I

    2012-04-01

    Ammonia oxidation, the first step in nitrification, is performed by autotrophic bacteria and thaumarchaea, whose relative contributions vary in different soils. Distinctive environmental niches for the two groups have not been identified, but evidence from previous studies suggests that activity of thaumarchaea, unlike that of bacterial ammonia oxidizers, is unaffected by addition of inorganic N fertilizer and that they preferentially utilize ammonia generated from the mineralization of organic N. This hypothesis was tested by determining the influence of both inorganic and organic N sources on nitrification rate and ammonia oxidizer growth and community structure in microcosms containing acidic, forest soil in which ammonia oxidation was dominated by thaumarchaea. Nitrification rate was unaffected by the incubation of soil with inorganic ammonium but was significantly stimulated by the addition of organic N. Oxidation of ammonia generated from native soil organic matter or added organic N, but not added inorganic N, was accompanied by increases in abundance of the thaumarchaeal amoA gene, a functional gene for ammonia oxidation, but changes in community structure were not observed. Bacterial amoA genes could not be detected. Ammonia oxidation was completely inhibited by 0.01% acetylene in all treatments, indicating ammonia monooxygenase-dependent activity. The findings have implications for current models of soil nitrification and for nitrification control strategies to minimize fertilizer loss and nitrous oxide production. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  9. Ammonia and nitrite oxidation in the Eastern Tropical North Pacific

    NASA Astrophysics Data System (ADS)

    Peng, Xuefeng; Fuchsman, Clara A.; Jayakumar, Amal; Oleynik, Sergey; Martens-Habbena, Willm; Devol, Allan H.; Ward, Bess B.

    2015-12-01

    Nitrification plays a key role in the marine nitrogen (N) cycle, including in oceanic oxygen minimum zones (OMZs), which are hot spots for denitrification and anaerobic ammonia oxidation (anammox). Recent evidence suggests that nitrification links the source (remineralized organic matter) and sink (denitrification and anammox) of fixed N directly in the steep oxycline in the OMZs. We performed shipboard incubations with 15N tracers to characterize the depth distribution of nitrification in the Eastern Tropical North Pacific (ETNP). Additional experiments were conducted to investigate photoinhibition. Allylthiourea (ATU) was used to distinguish the contribution of archaeal and bacterial ammonia oxidation. The abundance of archaeal and β-proteobacterial ammonia monooxygenase gene subunit A (amoA) was determined by quantitative polymerase chain reaction. The rates of ammonia and nitrite oxidation showed distinct subsurface maxima, with the latter slightly deeper than the former. The ammonia oxidation maximum coincided with the primary nitrite concentration maximum, archaeal amoA gene maximum, and the subsurface nitrous oxide maximum. Negligible rates of ammonia oxidation were found at anoxic depths, where high rates of nitrite oxidation were measured. Archaeal amoA gene abundance was generally 1 to 2 orders of magnitude higher than bacterial amoA gene abundance, and inhibition of ammonia-oxidizing bacteria with 10 μM ATU did not affect ammonia oxidation rates, indicating the dominance of archaea in ammonia oxidation. These results depict highly dynamic activities of ammonia and nitrite oxidation in the oxycline of the ETNP OMZ.

  10. Effects of Bacterial Community Members on the Proteome of the Ammonia-Oxidizing Bacterium Nitrosomonas sp. Strain Is79.

    PubMed

    Sedlacek, Christopher J; Nielsen, Susanne; Greis, Kenneth D; Haffey, Wendy D; Revsbech, Niels Peter; Ticak, Tomislav; Laanbroek, Hendrikus J; Bollmann, Annette

    2016-08-01

    Microorganisms in the environment do not exist as the often-studied pure cultures but as members of complex microbial communities. Characterizing the interactions within microbial communities is essential to understand their function in both natural and engineered environments. In this study, we investigated how the presence of a nitrite-oxidizing bacterium (NOB) and heterotrophic bacteria affect the growth and proteome of the chemolithoautotrophic ammonia-oxidizing bacterium (AOB) Nitrosomonas sp. strain Is79. We investigated Nitrosomonas sp. Is79 in co-culture with Nitrobacter winogradskyi, in co-cultures with selected heterotrophic bacteria, and as a member of the nitrifying enrichment culture G5-7. In batch culture, N. winogradskyi and heterotrophic bacteria had positive effects on the growth of Nitrosomonas sp. Is79. An isobaric tag for relative and absolute quantification (iTRAQ) liquid chromatography-tandem mass spectrometry (LC-MS/MS) proteomics approach was used to investigate the effect of N. winogradskyi and the co-cultured heterotrophic bacteria from G5-7 on the proteome of Nitrosomonas sp. Is79. In co-culture with N. winogradskyi, several Nitrosomonas sp. Is79 oxidative stress response proteins changed in abundance, with periplasmic proteins increasing and cytoplasmic proteins decreasing in abundance. In the presence of heterotrophic bacteria, the abundance of proteins directly related to the ammonia oxidation pathway increased, while the abundance of proteins related to amino acid synthesis and metabolism decreased. In summary, the proteome of Nitrosomonas sp. Is79 was differentially influenced by the presence of either N. winogradskyi or heterotrophic bacteria. Together, N. winogradskyi and heterotrophic bacteria reduced the oxidative stress for Nitrosomonas sp. Is79, which resulted in more efficient metabolism. Aerobic ammonia-oxidizing microorganisms play an important role in the global nitrogen cycle, converting ammonia to nitrite. In their

  11. Effects of Bacterial Community Members on the Proteome of the Ammonia-Oxidizing Bacterium Nitrosomonas sp. Strain Is79

    PubMed Central

    Sedlacek, Christopher J.; Nielsen, Susanne; Greis, Kenneth D.; Haffey, Wendy D.; Revsbech, Niels Peter; Ticak, Tomislav; Laanbroek, Hendrikus J.

    2016-01-01

    ABSTRACT Microorganisms in the environment do not exist as the often-studied pure cultures but as members of complex microbial communities. Characterizing the interactions within microbial communities is essential to understand their function in both natural and engineered environments. In this study, we investigated how the presence of a nitrite-oxidizing bacterium (NOB) and heterotrophic bacteria affect the growth and proteome of the chemolithoautotrophic ammonia-oxidizing bacterium (AOB) Nitrosomonas sp. strain Is79. We investigated Nitrosomonas sp. Is79 in co-culture with Nitrobacter winogradskyi, in co-cultures with selected heterotrophic bacteria, and as a member of the nitrifying enrichment culture G5-7. In batch culture, N. winogradskyi and heterotrophic bacteria had positive effects on the growth of Nitrosomonas sp. Is79. An isobaric tag for relative and absolute quantification (iTRAQ) liquid chromatography-tandem mass spectrometry (LC-MS/MS) proteomics approach was used to investigate the effect of N. winogradskyi and the co-cultured heterotrophic bacteria from G5-7 on the proteome of Nitrosomonas sp. Is79. In co-culture with N. winogradskyi, several Nitrosomonas sp. Is79 oxidative stress response proteins changed in abundance, with periplasmic proteins increasing and cytoplasmic proteins decreasing in abundance. In the presence of heterotrophic bacteria, the abundance of proteins directly related to the ammonia oxidation pathway increased, while the abundance of proteins related to amino acid synthesis and metabolism decreased. In summary, the proteome of Nitrosomonas sp. Is79 was differentially influenced by the presence of either N. winogradskyi or heterotrophic bacteria. Together, N. winogradskyi and heterotrophic bacteria reduced the oxidative stress for Nitrosomonas sp. Is79, which resulted in more efficient metabolism. IMPORTANCE Aerobic ammonia-oxidizing microorganisms play an important role in the global nitrogen cycle, converting ammonia to

  12. Diversity and Abundance of Ammonia-Oxidizing Archaeal Nitrite Reductase (nirK) Genes in Estuarine Sediments of San Francisco Bay

    NASA Astrophysics Data System (ADS)

    Reji, L.; Lee, J. A.; Damashek, J.; Francis, C. A.

    2013-12-01

    Nitrification, the microbially-mediated aerobic oxidation of ammonia to nitrate via nitrite, is an integral component of the global biogeochemical nitrogen cycle. The first and rate-limiting step of nitrification, ammonia oxidation, is carried out by two distinct microbial groups: ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA). Molecular ecological studies targeting the amoA gene have revealed the abundance and ubiquity of AOA in terrestrial as well as aquatic environments. In addition to the ammonia oxidation machinery that includes the amoA gene, AOA also encode a gene for copper-containing nitrite reductase (nirK). The distribution patterns and functional role of nirK in AOA remain mostly unknown; proposed functions include the indirect involvement in ammonia oxidation through the production of nitric oxide during nitrite reduction, and (2) nitrite detoxification. In the present study, the diversity and abundance of archaeal nirK genes in estuarine sediments were investigated using quantitative polymerase chain reaction, cloning and sequencing approaches. In sediment samples collected from the San Francisco Bay estuary, two archaeal nirK variants (AnirKa and AnirKb) were amplified using specific primer sets. Overall, AnirKa was observed to be significantly more abundant than AnirKb in the sediment samples, with variation in relative abundance spanning two to three orders of magnitude between sampling sites. Phylogenetic analysis revealed a number of unique archaeal nirK sequence types, as well as many that clustered with sequences from previous estuarine studies and cultured AOA isolates, such as Nitrosopumilus maritimus. This study yielded new insights into the diversity and abundance of archaeal nirK genes in estuarine sediments, and highlights the importance of further investigating the physiological role of this gene in AOA, as well as its suitability as a marker gene for studying AOA in the environment.

  13. Prevalence of Nitrosomonas cluster 7 populations in the ammonia-oxidizing community of a submerged membrane bioreactor treating urban wastewater under different operation conditions.

    PubMed

    Cerrone, F; Poyatos, J M; Molina-Muñoz, M; Cortés-Lorenzo, C; González-López, J; Rodelas, B

    2013-07-01

    A pilot-scale ultrafiltration membrane bioreactor (MBR) was used for the aerobic treatment of urban wastewater in four experimental stages influenced by seasonal temperature and different sets of operation conditions. The structure of the ammonia-oxidizing bacteria (AOB) community was profiled by temperature gradient gel electrophoresis (TGGE), based on the amplification and separation of partial ammonia-monoxygenase subunit A (amoA) genes. Canonical correspondence analysis revealed that temperature, hydraulic retention time and percentage of ammonia removal had a significant effect on the fingerprints of AOB communities. Phylogenetic analysis conducted on amoA/AmoA sequences of reamplified TGGE bands showed, however, that closely related ammonia-oxidizing populations inhabited the sludge of the MBR in all experimental stages. Nitrosomonas cluster 7 populations (N. europaea-N. eutropha cluster) prevailed under all conditions tested, even when the MBR was operated under complete biomass retention or at low temperatures, suggesting that the high ammonia concentrations in the system were determinant to select r-strategist AOB.

  14. Immobilization of ammonia-oxidizing bacteria by polyvinyl alcohol and sodium alginate.

    PubMed

    Dong, Yuwei; Zhang, Yanqiu; Tu, Baojun

    Ammonia-oxidizing bacteria were immobilized by polyvinyl alcohol (PVA) and sodium alginate. The immobilization conditions and ammonia oxidation ability of the immobilized bacteria were investigated. The following immobilization conditions were observed to be optimal: PVA, 12%; sodium alginate, 1.1%; calcium chloride, 1.0%; inoculum concentration, 1.3 immobilized balls/mL of immobilized medium; pH, 10; and temperature, 30°C. The immobilized ammonia-oxidizing bacteria exhibited strong ammonia oxidation ability even after being recycled four times. The ammonia nitrogen removal rate of the immobilized ammonia-oxidizing bacteria reached 90.30% under the optimal immobilization conditions. When compared with ammonia-oxidizing bacteria immobilized by sodium alginate alone, the bacteria immobilized by PVA and sodium alginate were superior with respect to pH resistance, the number of reuses, material cost, heat resistance, and ammonia oxidation ability. Copyright © 2017 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

  15. Physiological plasticity of the thermophilic ammonia oxidizing archaeon Nitrosocaldus yellowstonii in response to a changing environment

    NASA Astrophysics Data System (ADS)

    Jewell, T.; Johnson, A.; Gelsinger, D.; de la Torre, J. R.

    2012-12-01

    Our understanding of nitrogen biogeochemical cycling in high temperature environments underwent a dramatic revision with the discovery of ammonia oxidizing archaea (AOA). The importance of AOA to the global nitrogen cycle came to light when recent studies of marine AOA demonstrated the dominance of these organisms in the ocean microbiome and their role as producers of the greenhouse gas nitrous oxide (N2O). Understanding how AOA respond to fluctuating environments is crucial to fully comprehending their contribution to global biogeochemical cycling and climate change. In this study we use the thermophilic AOA Nitrosocaldus yellowstonii strain HL72 to explore the physiological plasticity of energy metabolism in these organisms. Previous studies have shown that HL72 grows autotrophically by aerobically oxidizing ammonia (NH3) to nitrite (NO2-). Unlike studies of marine AOA, we find that HL72 can grow over a wide ammonia concentration range (0.25 - 10 mM NH4Cl) with comparable generation times when in the presence of 0.25 to 4 mM NH4Cl. However, preliminary data indicate that amoA, the alpha subunit of ammonia monooxygenase (AMO), is upregulated at low ammonia concentrations (<50 μM) compared to growth at 1 mM. Although the ammonia oxidation pathway has not been fully elucidated, we have shown that nitric oxide (NO) appears to be a key intermediate: exponentially growing HL72 produces significant NO and the removal of NO using a scavenger reversibly inhibits growth. In addition to AMO, the HL72 genome also contains sequences for a urease encoded by subunits ureABC and an active urea transporter. Urea ((NH2)2CO) is an organic compound ubiquitous to aquatic and soil habitats that, when hydrolyzed, forms NH3 and CO2. We examined urea as an alternate source of ammonia for the ammonia oxidation pathway. HL72 grows over a wide range of urea concentrations (0.25 - 10 mM) at rates comparable to growth on ammonia. In a substrate competition experiment HL72 preferentially

  16. Ammonia oxidation: Ecology, physiology, biochemistry and why they must all come together.

    PubMed

    Lehtovirta-Morley, Laura E

    2018-05-01

    Ammonia oxidation is a fundamental core process in the global biogeochemical nitrogen cycle. Oxidation of ammonia (NH3) to nitrite (NO2 -) is the first and rate-limiting step in nitrification and is carried out by distinct groups of microorganisms. Ammonia oxidation is essential for nutrient turnover in most terrestrial, aquatic and engineered ecosystems and plays a major role, both directly and indirectly, in greenhouse gas production and environmental damage. Although ammonia oxidation has been studied for over a century, this research field has been galvanised in the past decade by the surprising discoveries of novel ammonia oxidising microorganisms. This review reflects on the ammonia oxidation research to date and discusses the major gaps remaining in our knowledge of the biology of ammonia oxidation.

  17. Removal of ammonia solutions used in catalytic wet oxidation processes.

    PubMed

    Hung, Chang Mao; Lou, Jie Chung; Lin, Chia Hua

    2003-08-01

    Ammonia (NH(3)) is an important product used in the chemical industry, and is common place in industrial wastewater. Industrial wastewater containing ammonia is generally either toxic or has concentrations or temperatures such that direct biological treatment is unfeasible. This investigation used aqueous solutions containing more of ammonia for catalytic liquid-phase oxidation in a trickle-bed reactor (TBR) based on Cu/La/Ce composite catalysts, prepared by co-precipitation of Cu(NO(3))(2), La(NO(3))(2), and Ce(NO(3))(3) at 7:2:1 molar concentrations. The experimental results indicated that the ammonia conversion of the wet oxidation in the presence of the Cu/La/Ce composite catalysts was determined by the Cu/La/Ce catalyst. Minimal ammonia was removed from the solution by the wet oxidation in the absence of any catalyst, while approximately 91% ammonia removal was achieved by wet oxidation over the Cu/La/Ce catalyst at 230 degrees C with oxygen partial pressure of 2.0 MPa. Furthermore, the effluent streams were conducted at a liquid hourly space velocity of under 9 h(-1) in the wet catalytic processes, and a reaction pathway was found linking the oxidizing ammonia to nitric oxide, nitrogen and water. The solution contained by-products, including nitrates and nitrites. Nitrite selectivity was minimized and ammonia removal maximized when the feed ammonia solution had a pH of around 12.0.

  18. Growth of ammonia-oxidizing archaea in soil microcosms is inhibited by acetylene.

    PubMed

    Offre, Pierre; Prosser, James I; Nicol, Graeme W

    2009-10-01

    Autotrophic ammonia-oxidizing bacteria were considered to be responsible for the majority of ammonia oxidation in soil until the recent discovery of the autotrophic ammonia-oxidizing archaea. To assess the relative contributions of bacterial and archaeal ammonia oxidizers to soil ammonia oxidation, their growth was analysed during active nitrification in soil microcosms incubated for 30 days at 30 degrees C, and the effect of an inhibitor of ammonia oxidation (acetylene) on their growth and soil nitrification kinetics was determined. Denaturing gradient gel electrophoresis (DGGE) analysis of bacterial ammonia oxidizer 16S rRNA genes did not detect any change in their community composition during incubation, and quantitative PCR (qPCR) analysis of bacterial amoA genes indicated a small decrease in abundance in control and acetylene-containing microcosms. DGGE fingerprints of archaeal amoA and 16S rRNA genes demonstrated changes in the relative abundance of specific crenarchaeal phylotypes during active nitrification. Growth was also indicated by increases in crenarchaeal amoA gene copy number, determined by qPCR. In microcosms containing acetylene, nitrification and growth of the crenarchaeal phylotypes were suppressed, suggesting that these crenarchaea are ammonia oxidizers. Growth of only archaeal but not bacterial ammonia oxidizers occurred in microcosms with active nitrification, indicating that ammonia oxidation was mostly due to archaea in the conditions of the present study.

  19. Pathways and key intermediates required for obligate aerobic ammonia-dependent chemolithotrophy in bacteria and Thaumarchaeota

    PubMed Central

    Kozlowski, Jessica A; Stieglmeier, Michaela; Schleper, Christa; Klotz, Martin G; Stein, Lisa Y

    2016-01-01

    Chemolithotrophic ammonia-oxidizing bacteria and Thaumarchaeota are central players in the global nitrogen cycle. Obligate ammonia chemolithotrophy has been characterized for bacteria; however, large gaps remain in the Thaumarchaeotal pathway. Using batch growth experiments and instantaneous microrespirometry measurements of resting biomass, we show that the terrestrial Thaumarchaeon Nitrososphaera viennensis EN76T exhibits tight control over production and consumption of nitric oxide (NO) during ammonia catabolism, unlike the ammonia-oxidizing bacterium Nitrosospira multiformis ATCC 25196T. In particular, pulses of hydroxylamine into a microelectrode chamber as the sole substrate for N. viennensis resulted in iterative production and consumption of NO followed by conversion of hydroxylamine to nitrite. In support of these observations, oxidation of ammonia in growing cultures of N. viennensis, but not of N. multiformis, was inhibited by the NO-scavenger PTIO. When based on the marginal nitrous oxide (N2O) levels detected in cell-free media controls, the higher levels produced by N. multiformis were explained by enzyme activity, whereas N2O in N. viennensis cultures was attributed to abiotic reactions of released N-oxide intermediates with media components. Our results are conceptualized in a pathway for ammonia-dependent chemolithotrophy in Thaumarchaea, which identifies NO as an essential intermediate in the pathway and implements known biochemistry to be executed by a proposed but still elusive copper enzyme. Taken together, this work identifies differences in ammonia-dependent chemolithotrophy between bacteria and the Thaumarchaeota, advances a central catabolic role of NO only in the Thaumarchaeotal pathway and reveals stark differences in how the two microbial cohorts contribute to N2O emissions. PMID:26882267

  20. Quantitative analyses of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in fields with different soil types.

    PubMed

    Morimoto, Sho; Hayatsu, Masahito; Takada Hoshino, Yuko; Nagaoka, Kazunari; Yamazaki, Masatsugu; Karasawa, Toshihiko; Takenaka, Makoto; Akiyama, Hiroko

    2011-01-01

    Soil type is one of the key factors affecting soil microbial communities. With regard to ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB), however, it has not been determined how soil type affects their community size and soil nitrification activity. Here we quantitatively analyzed the ammonia monooxygenase genes (amoA) of these ammonia oxidizers in fields with three different soil types (Low-humic Andosol [LHA], Gray Lowland Soil [GLS], and Yellow Soil [YS]) under common cropping conditions, and assessed the relationships between soil nitrification activity and the abundance of each amoA. Nitrification activity of LHA was highest, followed by that of GLS and YS; this order was consistent with that for the abundance of AOB amoA. Abundance of AOB amoA showed temporal variation, which was similar to that observed in nitrification activity, and a strong relationship (adjusted R(2)=0.742) was observed between the abundance of AOB amoA and nitrification activity. Abundance of AOA amoA also exhibited a significant relationship (adjusted R(2)=0.228) with nitrification activity, although this relationship was much weaker. Our results indicate that soil type affects the community size of AOA and AOB and the resulting nitrification activity, and that AOB are major contributors to nitrification in soils, while AOA are partially responsible.

  1. Manure fertilization alters the population of ammonia-oxidizing bacteria rather than ammonia-oxidizing archaea in a paddy soil.

    PubMed

    Wang, Yu; Zhu, Guibing; Song, Liyan; Wang, Shanyun; Yin, Chengqing

    2014-03-01

    Manure fertilizers are widely used in agriculture and highly impacted the soil microbial communities such as ammonia oxidizers. However, the knowledge on the communities of archaeal versus bacterial ammonia oxidizers in paddy soil affected by manure fertilization remains largely unknown, especially for a long-term influence. In present work, the impact of manure fertilization on the population of ammonia oxidizers, related potential nitrification rates (PNRs) and the key factors manipulating the impact were investigated through studying two composite soil cores (long-term fed with manure fertilization versus undisturbed). Moreover, soil incubated with NH(4)(+) for 5 weeks was designed to verify the field research. The results showed that the copy numbers of bacterial amoA gene in the manure fed soil were significant higher than those in the unfed soil (p < 0.05), suggesting a clear stimulating effect of long-term manure fertilization on the population of ammonia-oxidizing bacteria (AOB). The detected PNRs in the manure fed soil core (14-218 nmol L(-1)  N g(-1)  h(-1)) were significant higher than those in the unfed soil core (5-72 nmol L(-1)  N g(-1)  h(-1) ; p < 0.05). Highly correlations between the PNRs and the bacterial amoA gene copies rather than archaeal amoA gene were observed, indicating strong nitrification capacity related to bacterial ammonia oxidizers. The NH(4)(+) -N significantly correlated to the abundance of AOB (p < 0.01) and explained 96.1% of the environmental variation, showing the NH(4)(+) -N was the main factor impacting the population of AOB. The incubation experiment demonstrated a clear increase of the bacterial amoA gene abundance (2.0 × 10(6) to 8.4 × 10(6)  g(-1) d.w.s. and 1.6 × 10(4) to 4.8 × 10(5)  g(-1) d.w.s.) in both soil but not for the archaeal amoA gene, in agreement with the field observation. Overall, our results suggested that manure fertilization promoted the

  2. [Diversity of beta-proteobacterial ammonia-oxidizing bacteria and ammonia-oxidizing archaea in shrimp farm sediment].

    PubMed

    Gao, Lihai; Lin, Weitie

    2011-01-01

    In order to study the diversity of ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) in shrimp farm sediment. Total microbial DNA was directly extracted from the shrimp farm sediment. The clone library of amoA genes were constructed with beta-Proteobacterial-AOB and AOA specific primers. The library was screened by PCR-restriction fragment length polymorphism (RFLP) analysis and clones with unique RFLP patterns were sequenced. Phylogenetic analyses of the amoA gene fragments showed that all AOB sequences from shrimp farm sediment were affiliated with Nitrosomonas (61.54%) or Nitrosomonas-like (38. 46%) species and grouped into Nitrosomonas communis cluster, Nitrosomonas sp. Nm148 cluster, Nitrosomonas oligotropha cluster. All AOA sequences belonged to the kingdom Crenarchaeote except that one Operational Taxa Unit (OTU) sequence was Unclassified-Archaea and fell within cluster S (soil origin). AOB and AOA species composition included 13 OTUs and 9 OTUs. The clone coverage of bacterial and archaeal amoA genes was 73.47% and 90.43%. The Shannon-Wiener index, Evenness index, Simpson index and Richness index of AOB were higher than those of AOA. These findings represent the first detailed examination of archaeal amoA diversity in shrimp farm sediment and demonstrate that diverse communities of Crenarchaeote capable of ammonia oxidation are present within shrimp farm sediment, where they may be actively involved in nitrification.

  3. Diversity, abundance and activity of ammonia-oxidizing microorganisms in fine particulate matter

    PubMed Central

    Gao, Jing-Feng; Fan, Xiao-Yan; Pan, Kai-Ling; Li, Hong-Yu; Sun, Li-Xin

    2016-01-01

    Increasing ammonia emissions could exacerbate air pollution caused by fine particulate matter (PM2.5). Therefore, it is of great importance to investigate ammonia oxidation in PM2.5. This study investigated the diversity, abundance and activity of ammonia oxidizing archaea (AOA), ammonia oxidizing bacteria (AOB) and complete ammonia oxidizers (Comammox) in PM2.5 collected in Beijing-Tianjin-Hebei megalopolis, China. Nitrosopumilus subcluster 5.2 was the most dominant AOA. Nitrosospira multiformis and Nitrosomonas aestuarii were the most dominant AOB. Comammox were present in the atmosphere, as revealed by the occurrence of Candidatus Nitrospira inopinata in PM2.5. The average cell numbers of AOA, AOB and Ca. N. inopinata were 2.82 × 104, 4.65 × 103 and 1.15 × 103 cell m−3 air, respectively. The average maximum nitrification rate of PM2.5 was 0.14 μg (NH4+-N) [m3 air·h]−1. AOA might account for most of the ammonia oxidation, followed by Comammox, while AOB were responsible for a small part of ammonia oxidation. Statistical analyses showed that Nitrososphaera subcluster 4.1 was positively correlated with organic carbon concentration, and Nitrosomonas eutropha showed positive correlation with ammonia concentration. Overall, this study expanded our knowledge concerning AOA, AOB and Comammox in PM2.5 and pointed towards an important role of AOA and Comammox in ammonia oxidation in PM2.5. PMID:27941955

  4. Nitrification of archaeal ammonia oxidizers in a high- temperature hot spring

    NASA Astrophysics Data System (ADS)

    Chen, Shun; Peng, Xiaotong; Xu, Hengchao; Ta, Kaiwen

    2016-04-01

    The oxidation of ammonia by microbes has been shown to occur in diverse natural environments. However, the link of in situ nitrification activity to taxonomic identities of ammonia oxidizers in high-temperature environments remains poorly understood. Here, we studied in situ ammonia oxidation rates and the diversity of ammonia-oxidizing Archaea (AOA) in surface and bottom sediments at 77 °C in the Gongxiaoshe hot spring, Tengchong, Yunnan, China. The in situ ammonia oxidation rates measured by the 15N-NO3- pool dilution technique in the surface and bottom sediments were 4.80 and 5.30 nmol N g-1 h-1, respectively. Real-time quantitative polymerase chain reaction (qPCR) indicated that the archaeal 16S rRNA genes and amoA genes were present in the range of 0.128 to 1.96 × 108 and 2.75 to 9.80 × 105 gene copies g-1 sediment, respectively, while bacterial amoA was not detected. Phylogenetic analysis of 16S rRNA genes showed high sequence similarity to thermophilic Candidatus Nitrosocaldus yellowstonii, which represented the most abundant operational taxonomic units (OTU) in both surface and bottom sediments. The archaeal predominance was further supported by fluorescence in situ hybridization (FISH) visualization. The cell-specific rate of ammonia oxidation was estimated to range from 0.410 to 0.790 fmol N archaeal cell-1 h-1, higher than those in the two US Great Basin hot springs. These results suggest the importance of archaeal rather than bacterial ammonia oxidation in driving the nitrogen cycle in terrestrial geothermal environments.

  5. Ammonia oxidation kinetics and temperature sensitivity of a natural marine community dominated by Archaea

    PubMed Central

    Horak, Rachel E A; Qin, Wei; Schauer, Andy J; Armbrust, E Virginia; Ingalls, Anitra E; Moffett, James W; Stahl, David A; Devol, Allan H

    2013-01-01

    Archaeal ammonia oxidizers (AOAs) are increasingly recognized as prominent members of natural microbial assemblages. Evidence that links the presence of AOA with in situ ammonia oxidation activity is limited, and the abiotic factors that regulate the distribution of AOA natural assemblages are not well defined. We used quantitative PCR to enumerate amoA (encodes α-subunit of ammonia monooxygenase) abundances; AOA amoA gene copies greatly outnumbered ammonia-oxidizing bacteria and amoA transcripts were derived primarily from AOA throughout the water column of Hood Canal, Puget Sound, WA, USA. We generated a Michaelis–Menten kinetics curve for ammonia oxidation by the natural community and found that the measured Km of 98±14 nmol l−1 was close to that for cultivated AOA representative Nitrosopumilus maritimus SCM1. Temperature did not have a significant effect on ammonia oxidation rates for incubation temperatures ranging from 8 to 20 °C, which is within the temperature range for depths of measurable ammonia oxidation at the site. This study provides substantial evidence, through both amoA gene copies and transcript abundances and the kinetics response, that AOA are the dominant active ammonia oxidizers in this marine environment. We propose that future ammonia oxidation experiments use a Km for the natural community to better constrain ammonia oxidation rates determined with the commonly used 15NH4+ dilution technique. PMID:23657360

  6. Ammonia oxidation kinetics and temperature sensitivity of a natural marine community dominated by Archaea.

    PubMed

    Horak, Rachel E A; Qin, Wei; Schauer, Andy J; Armbrust, E Virginia; Ingalls, Anitra E; Moffett, James W; Stahl, David A; Devol, Allan H

    2013-10-01

    Archaeal ammonia oxidizers (AOAs) are increasingly recognized as prominent members of natural microbial assemblages. Evidence that links the presence of AOA with in situ ammonia oxidation activity is limited, and the abiotic factors that regulate the distribution of AOA natural assemblages are not well defined. We used quantitative PCR to enumerate amoA (encodes α-subunit of ammonia monooxygenase) abundances; AOA amoA gene copies greatly outnumbered ammonia-oxidizing bacteria and amoA transcripts were derived primarily from AOA throughout the water column of Hood Canal, Puget Sound, WA, USA. We generated a Michaelis-Menten kinetics curve for ammonia oxidation by the natural community and found that the measured Km of 98±14 nmol l(-1) was close to that for cultivated AOA representative Nitrosopumilus maritimus SCM1. Temperature did not have a significant effect on ammonia oxidation rates for incubation temperatures ranging from 8 to 20 °C, which is within the temperature range for depths of measurable ammonia oxidation at the site. This study provides substantial evidence, through both amoA gene copies and transcript abundances and the kinetics response, that AOA are the dominant active ammonia oxidizers in this marine environment. We propose that future ammonia oxidation experiments use a Km for the natural community to better constrain ammonia oxidation rates determined with the commonly used (15)NH4(+) dilution technique.

  7. Co(salophen)-Catalyzed Aerobic Oxidation of p-Hydroquinone: Mechanism and Implications for Aerobic Oxidation Catalysis.

    PubMed

    Anson, Colin W; Ghosh, Soumya; Hammes-Schiffer, Sharon; Stahl, Shannon S

    2016-03-30

    Macrocyclic metal complexes and p-benzoquinones are commonly used as co-catalytic redox mediators in aerobic oxidation reactions. In an effort to gain insight into the mechanism and energetic efficiency of these reactions, we investigated Co(salophen)-catalyzed aerobic oxidation of p-hydroquinone. Kinetic and spectroscopic data suggest that the catalyst resting-state consists of an equilibrium between a Co(II)(salophen) complex, a Co(III)-superoxide adduct, and a hydrogen-bonded adduct between the hydroquinone and the Co(III)-O2 species. The kinetic data, together with density functional theory computational results, reveal that the turnover-limiting step involves proton-coupled electron transfer from a semi-hydroquinone species and a Co(III)-hydroperoxide intermediate. Additional experimental and computational data suggest that a coordinated H2O2 intermediate oxidizes a second equivalent of hydroquinone. Collectively, the results show how Co(salophen) and p-hydroquinone operate synergistically to mediate O2 reduction and generate the reactive p-benzoquinone co-catalyst.

  8. Mimicking the oxygen minimum zones: stimulating interaction of aerobic archaeal and anaerobic bacterial ammonia oxidizers in a laboratory-scale model system

    PubMed Central

    Yan, Jia; Haaijer, Suzanne C M; Op den Camp, Huub J M; Niftrik, Laura; Stahl, David A; Könneke, Martin; Rush, Darci; Sinninghe Damsté, Jaap S; Hu, Yong Y; Jetten, Mike S M

    2012-01-01

    In marine oxygen minimum zones (OMZs), ammonia-oxidizing archaea (AOA) rather than marine ammonia-oxidizing bacteria (AOB) may provide nitrite to anaerobic ammonium-oxidizing (anammox) bacteria. Here we demonstrate the cooperation between marine anammox bacteria and nitrifiers in a laboratory-scale model system under oxygen limitation. A bioreactor containing ‘Candidatus Scalindua profunda’ marine anammox bacteria was supplemented with AOA (Nitrosopumilus maritimus strain SCM1) cells and limited amounts of oxygen. In this way a stable mixed culture of AOA, and anammox bacteria was established within 200 days while also a substantial amount of endogenous AOB were enriched. ‘Ca. Scalindua profunda’ and putative AOB and AOA morphologies were visualized by transmission electron microscopy and a C18 anammox [3]-ladderane fatty acid was highly abundant in the oxygen-limited culture. The rapid oxygen consumption by AOA and AOB ensured that anammox activity was not affected. High expression of AOA, AOB and anammox genes encoding for ammonium transport proteins was observed, likely caused by the increased competition for ammonium. The competition between AOA and AOB was found to be strongly related to the residual ammonium concentration based on amoA gene copy numbers. The abundance of archaeal amoA copy numbers increased markedly when the ammonium concentration was below 30 μM finally resulting in almost equal abundance of AOA and AOB amoA copy numbers. Massive parallel sequencing of mRNA and activity analyses further corroborated equal abundance of AOA and AOB. PTIO addition, inhibiting AOA activity, was employed to determine the relative contribution of AOB versus AOA to ammonium oxidation. The present study provides the first direct evidence for cooperation of archaeal ammonia oxidation with anammox bacteria by provision of nitrite and consumption of oxygen. PMID:23057688

  9. The study of a pilot-scale aerobic/Fenton/anoxic/aerobic process system for the treatment of landfill leachate.

    PubMed

    Hu, Wenyong; Zhou, Yu; Min, Xiaobo; Liu, Jingyi; Li, Xinyu; Luo, Lin; Zhang, Jiachao; Mao, Qiming; Chai, Liyuan; Zhou, YaoYu

    2017-06-29

    In this study, a combined aerobic-Fenton-anoxic/aerobic system was designed for the remediation of raw landfill leachate in a pilot-scale experiment. This system included (i) a granular sludge biological oxidation procedure that achieves the accumulation of nitrite nitrogen ([Formula: see text]) under aerobic conditions; (ii) a Fenton process that improves the biodegradability of the biotreated leachate and (iii) an activated sludge biological oxidation component under anoxic and aerobic conditions. Additionally, a shortcut nitrification and denitrification pathway was achieved. The effects of free ammonia, temperature and pH on nitrite accumulation were discussed. The change in the biochemical oxygen demand/chemical oxygen demand ratio of the effluent after shortcut nitrification was also analysed. The microbial community in the reactor were also investigated. The problem of the lack of carbon source in the denitrification process can be solved by the Fenton reagent method. Moreover, it was beneficial to achieving nitrogen removal as well as the more extensive removal of organic matter. The treatment strategy employed in this study exhibited good results and provided the potential practical application for treating landfill leachate.

  10. Mathematical Modeling of Ammonia Electro-Oxidation on Polycrystalline Pt Deposited Electrodes

    NASA Astrophysics Data System (ADS)

    Diaz Aldana, Luis A.

    The ammonia electrolysis process has been proposed as a feasible way for electrochemical generation of fuel grade hydrogen (H2). Ammonia is identified as one of the most suitable energy carriers due to its high hydrogen density, and its safe and efficient distribution chain. Moreover, the fact that this process can be applied even at low ammonia concentration feedstock opens its application to wastewater treatment along with H 2 co-generation. In the ammonia electrolysis process, ammonia is electro-oxidized in the anode side to produce N2 while H2 is evolved from water reduction in the cathode. A thermodynamic energy requirement of just five percent of the energy used in hydrogen production from water electrolysis is expected from ammonia electrolysis. However, the absence of a complete understanding of the reaction mechanism and kinetics involved in the ammonia electro-oxidation has not yet allowed the full commercialization of this process. For that reason, a kinetic model that can be trusted in the design and scale up of the ammonia electrolyzer needs to be developed. This research focused on the elucidation of the reaction mechanism and kinetic parameters for the ammonia electro-oxidation. The definition of the most relevant elementary reactions steps was obtained through the parallel analysis of experimental data and the development of a mathematical model of the ammonia electro-oxidation in a well defined hydrodynamic system, such as the rotating disk electrode (RDE). Ammonia electro-oxidation to N 2 as final product was concluded to be a slow surface confined process where parallel reactions leading to the deactivation of the catalyst are present. Through the development of this work it was possible to define a reaction mechanism and values for the kinetic parameters for ammonia electro-oxidation that allow an accurate representation of the experimental observations on a RDE system. Additionally, the validity of the reaction mechanism and kinetic parameters

  11. Ammonia-oxidizing archaea versus bacteria in two soil aquifer treatment systems.

    PubMed

    Ding, Kun; Wen, Xianghua; Li, Yuyang; Shen, Bo; Zhang, Bing

    2015-02-01

    So far, the contribution of ammonia-oxidizing archaea (AOA) to ammonia oxidation in wastewater treatment processes has not been well understood. In this study, two soil aquifer treatment (SATs) systems were built up to treat synthetic domestic wastewater (column 1) and secondary effluent (column 4), accomplishing an average of 95% ammonia removal during over 550 days of operation. Except at day 322, archaeal amoA genes always outnumbered bacterial amoA genes in both SATs as determined by using quantitative polymerase chain reaction (q-PCR). The ratios of archaeal amoA to 16S rRNA gene averaged at 0.70 ± 0.56 and 0.82 ± 0.62 in column 1 and column 4, respectively, indicating that all the archaea could be AOA carrying amoA gene in the SATs. The results of MiSeq-pyrosequencing targeting on archaeal and bacterial 16S rRNA genes with the primer pair of modified 515R/806R indicated that Nitrososphaera cluster affiliated with thaumarchaeal group I.1b was the dominant AOA species, while Nitrosospira cluster was the dominant ammonia-oxidizing bacteria (AOB). The statistical analysis showed significant relationship between AOA abundance (compared to AOB abundance) and inorganic and total nitrogen concentrations. Based on the mathematical model calculation for microbial growth, AOA had much greater capacity of ammonia oxidation as compared to the specific influent ammonia loading for AOA in the SATs, implying that a small fraction of the total AOA would actively work to oxidize ammonia chemoautotrophically whereas most of AOA would exhibit some level of functional redundancy. These results all pointed that AOA involved in microbial ammonia oxidation in the SATs.

  12. Degradation of trichloroethylene by the ammonia-oxidizing bacterium Nitrosomonas europaea.

    PubMed

    Arciero, D; Vannelli, T; Logan, M; Hooper, A B

    1989-03-15

    Suspensions of Nitrosomonas europaea are shown to cause the complete disappearance of 10 microM trichloroethylene at rates of 1 microM mg protein-1. The reaction continues at nearly this rate for many hours. Fresh cells catalyze the reaction in the absence of added ammonium (presumably utilizing endogenous ammonia or stored reductant). In older cells, trichloroethylene degradation depends on the addition of ammonia. Acetylene, 2-chloro 6-trichloromethylpyridine and alpha alpha'dipyridyl, which inhibit the oxidation of ammonia by cells, inhibit the degradation of trichloroethylene. Thus degradation of trichloroethylene is dependent on- and possibly catalyzed by the ammonia oxidizing enzyme.

  13. Ammonia oxidation kinetics determine niche separation of nitrifying Archaea and Bacteria.

    PubMed

    Martens-Habbena, Willm; Berube, Paul M; Urakawa, Hidetoshi; de la Torre, José R; Stahl, David A

    2009-10-15

    The discovery of ammonia oxidation by mesophilic and thermophilic Crenarchaeota and the widespread distribution of these organisms in marine and terrestrial environments indicated an important role for them in the global nitrogen cycle. However, very little is known about their physiology or their contribution to nitrification. Here we report oligotrophic ammonia oxidation kinetics and cellular characteristics of the mesophilic crenarchaeon 'Candidatus Nitrosopumilus maritimus' strain SCM1. Unlike characterized ammonia-oxidizing bacteria, SCM1 is adapted to life under extreme nutrient limitation, sustaining high specific oxidation rates at ammonium concentrations found in open oceans. Its half-saturation constant (K(m) = 133 nM total ammonium) and substrate threshold (ammonia-oxidizing Archaea to oligotrophic nitrification. The remarkably high specific affinity for reduced nitrogen (68,700 l per g cells per h) of SCM1 suggests that Nitrosopumilus-like ammonia-oxidizing Archaea could successfully compete with heterotrophic bacterioplankton and phytoplankton. Together these findings support the hypothesis that nitrification is more prevalent in the marine nitrogen cycle than accounted for in current biogeochemical models.

  14. SOIL NITROUS OXIDE, NITRIC OXIDE, AND AMMONIA EMISSIONS FROM A RECOVERING RIPARIAN ECOSYSTEM IN SOUTHERN APPALACHIA

    EPA Science Inventory

    The paper presents two years of seasonal nitric oxide, ammonia, and nitrous oxide trace gas fluxes measured in a recovering riparian zone with cattle excluded and in an adjacent riparian zone grazed by cattle. In the recovering riparian zone, average nitric oxide, ammonia, and ni...

  15. Catalytic wet oxidation of ammonia solution: activity of the nanoscale platinum-palladium-rhodium composite oxide catalyst.

    PubMed

    Hung, Chang-Mao

    2009-04-15

    Aqueous solutions of 400-1000 mg/L of ammonia were oxidized in a trickle-bed reactor (TBR) in this study of nanoscale platinum-palladium-rhodium composite oxide catalysts, which were prepared by the co-precipitation of H(2)PtCl(6), Pd(NO(3))(3) and Rh(NO(3))(3). Hardly any of the dissolved ammonia was removed by wet oxidation in the absence of any catalyst, whereas about 99% of the ammonia was reduced during wet oxidation over nanoscale platinum-palladium-rhodium composite oxide catalysts at 503 K in an oxygen partial pressure of 2.0 MPa. A synergistic effect exists in the nanoscale platinum-palladium-rhodium composite structure, which is the material with the highest ammonia reduction activity. The nanometer-sized particles were characterized by TEM, XRD and FTIR. The effect of the initial concentration and reaction temperature on the removal of ammonia from the effluent streams was also studied at a liquid hourly space velocity of under 9 h(-1) in the wet catalytic processes.

  16. Growth of ammonia-oxidizing archaea and bacteria in cattle manure compost under various temperatures and ammonia concentrations.

    PubMed

    Oishi, Ryu; Tada, Chika; Asano, Ryoki; Yamamoto, Nozomi; Suyama, Yoshihisa; Nakai, Yutaka

    2012-05-01

    A recent study showed that ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) coexist in the process of cattle manure composting. To investigate their physiological characteristics, liquid cultures seeded with fermenting cattle manure compost were incubated at various temperatures (37°C, 46°C, or 60°C) and ammonium concentrations (0.5, 1, 4, or 10 mM NH (4) (+) -N). The growth rates of the AOB and AOA were monitored using real-time polymerase chain reaction analysis targeting the bacterial and archaeal ammonia monooxygenase subunit A genes. AOB grew at 37°C and 4 or 10 mM NH (4) (+) -N, whereas AOA grew at 46°C and 10 mM NH (4) (+) -N. Incubation with allylthiourea indicated that the AOB and AOA grew by oxidizing ammonia. Denaturing gradient gel electrophoresis and subsequent sequencing analyses revealed that a bacterium related to Nitrosomonas halophila and an archaeon related to Candidatus Nitrososphaera gargensis were the predominant AOB and AOA, respectively, in the seed compost and in cultures after incubation. This is the first report to demonstrate that the predominant AOA in cattle manure compost can grow and can probably oxidize ammonia under moderately thermophilic conditions.

  17. Ammonia oxidation rates and nitrification in the Arabian Sea

    NASA Astrophysics Data System (ADS)

    Newell, Silvia E.; Babbin, Andrew R.; Jayakumar, Amal; Ward, Bess B.

    2011-12-01

    Nitrification rates, as well as the relationships between rates and ammonia oxidizer abundance (both archaeal and bacterial), were investigated in the Arabian Sea. Ammonia oxidation rates were measured directly using 15N-NH4+stable isotope additions in gas-impermeable, trace metal clean trilaminate bags (500 mL) at in situ temperature. Tracer incubations were performed at three stations at depths above, below, and within the oxycline of the open-ocean oxygen minimum zone (OMZ). Ammonia oxidation rates were similar to previous open-ocean measurements, ranging from undetectable to 21.6 ± 0.1 nmol L-1 d-1. The highest rates at each station occurred at the primary nitrite maximum (above the OMZ), and rates were very low at depths greater than 900 m. The abundances of both ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) were estimated using theamoA gene by quantitative polymerase chain reaction (qPCR). Both AOA and AOB amoA were detected above, within, and below the OMZ, although the AOA were always more abundant than the AOB, by a factor of 35-216. Nitrification rates were not directly correlated to AOA or AOB amoA abundance. These rates offer new insight into the role of nitrification in the mesopelagic zone. The abundance of AOA amoA genes at 1000 m suggests that ˜50% of the microbial biomass could be autotrophic. Additionally, the integrated nitrification rate at depth implies that nitrification could consume most of the ammonium produced by the flux of organic carbon in the mesopelagic zone.

  18. Nitrogen and Oxygen Isotope Effects of Ammonia Oxidation by Thermophilic Thaumarchaeota from a Geothermal Water Stream

    PubMed Central

    Sakai, Sanae; Konno, Uta; Nakahara, Nozomi; Takaki, Yoshihiro; Saito, Yumi; Imachi, Hiroyuki; Tasumi, Eiji; Makabe, Akiko; Koba, Keisuke; Takai, Ken

    2016-01-01

    ABSTRACT Ammonia oxidation regulates the balance of reduced and oxidized nitrogen pools in nature. Although ammonia-oxidizing archaea have been recently recognized to often outnumber ammonia-oxidizing bacteria in various environments, the contribution of ammonia-oxidizing archaea is still uncertain due to difficulties in the in situ quantification of ammonia oxidation activity. Nitrogen and oxygen isotope ratios of nitrite (δ15NNO2− and δ18ONO2−, respectively) are geochemical tracers for evaluating the sources and the in situ rate of nitrite turnover determined from the activities of nitrification and denitrification; however, the isotope ratios of nitrite from archaeal ammonia oxidation have been characterized only for a few marine species. We first report the isotope effects of ammonia oxidation at 70°C by thermophilic Thaumarchaeota populations composed almost entirely of “Candidatus Nitrosocaldus.” The nitrogen isotope effect of ammonia oxidation varied with ambient pH (25‰ to 32‰) and strongly suggests the oxidation of ammonia, not ammonium. The δ18O value of nitrite produced from ammonia oxidation varied with the δ18O value of water in the medium but was lower than the isotopic equilibrium value in water. Because experiments have shown that the half-life of abiotic oxygen isotope exchange between nitrite and water is longer than 33 h at 70°C and pH ≥6.6, the rate of ammonia oxidation by thermophilic Thaumarchaeota could be estimated using δ18ONO2− in geothermal environments, where the biological nitrite turnover is likely faster than 33 h. This study extended the range of application of nitrite isotopes as a geochemical clock of the ammonia oxidation activity to high-temperature environments. IMPORTANCE Because ammonia oxidation is generally the rate-limiting step in nitrification that regulates the balance of reduced and oxidized nitrogen pools in nature, it is important to understand the biological and environmental factors underlying

  19. Nitrogen and Oxygen Isotope Effects of Ammonia Oxidation by Thermophilic Thaumarchaeota from a Geothermal Water Stream.

    PubMed

    Nishizawa, Manabu; Sakai, Sanae; Konno, Uta; Nakahara, Nozomi; Takaki, Yoshihiro; Saito, Yumi; Imachi, Hiroyuki; Tasumi, Eiji; Makabe, Akiko; Koba, Keisuke; Takai, Ken

    2016-08-01

    Ammonia oxidation regulates the balance of reduced and oxidized nitrogen pools in nature. Although ammonia-oxidizing archaea have been recently recognized to often outnumber ammonia-oxidizing bacteria in various environments, the contribution of ammonia-oxidizing archaea is still uncertain due to difficulties in the in situ quantification of ammonia oxidation activity. Nitrogen and oxygen isotope ratios of nitrite (δ(15)NNO2- and δ(18)ONO2-, respectively) are geochemical tracers for evaluating the sources and the in situ rate of nitrite turnover determined from the activities of nitrification and denitrification; however, the isotope ratios of nitrite from archaeal ammonia oxidation have been characterized only for a few marine species. We first report the isotope effects of ammonia oxidation at 70°C by thermophilic Thaumarchaeota populations composed almost entirely of "Candidatus Nitrosocaldus." The nitrogen isotope effect of ammonia oxidation varied with ambient pH (25‰ to 32‰) and strongly suggests the oxidation of ammonia, not ammonium. The δ(18)O value of nitrite produced from ammonia oxidation varied with the δ(18)O value of water in the medium but was lower than the isotopic equilibrium value in water. Because experiments have shown that the half-life of abiotic oxygen isotope exchange between nitrite and water is longer than 33 h at 70°C and pH ≥6.6, the rate of ammonia oxidation by thermophilic Thaumarchaeota could be estimated using δ(18)ONO2- in geothermal environments, where the biological nitrite turnover is likely faster than 33 h. This study extended the range of application of nitrite isotopes as a geochemical clock of the ammonia oxidation activity to high-temperature environments. Because ammonia oxidation is generally the rate-limiting step in nitrification that regulates the balance of reduced and oxidized nitrogen pools in nature, it is important to understand the biological and environmental factors underlying the regulation of

  20. Intensive management affects composition of betaproteobacterial ammonia oxidizers in turfgrass systems.

    PubMed

    Dell, Emily A; Bowman, Daniel; Rufty, Thomas; Shi, Wei

    2008-07-01

    Turfgrass is a highly managed ecosystem subject to frequent fertilization, mowing, irrigation, and application of pesticides. Turf management practices may create a perturbed environment for ammonia oxidizers, a key microbial group responsible for nitrification. To elucidate the long-term effects of turf management on these bacteria, we assessed the composition of betaproteobacterial ammonia oxidizers in a chronosequence of turfgrass systems (i.e., 1, 6, 23, and 95 years old) and the adjacent native pines by using both 16S rRNA and amoA gene fragments specific to ammonia oxidizers. Based on the Shannon-Wiener diversity index of denaturing gradient gel electrophoresis patterns and the rarefaction curves of amoA clones, turf management did not change the relative diversity and richness of ammonia oxidizers in turf soils as compared to native pine soils. Ammonia oxidizers in turfgrass systems comprised a suite of phylogenetic clusters common to other terrestrial ecosystems. Nitrosospira clusters 0, 2, 3, and 4; Nitrosospira sp. Nsp65-like sequences; and Nitrosomonas clusters 6 and 7 were detected in the turfgrass chronosequence with Nitrosospira clusters 3 and 4 being dominant. However, both turf age and land change (pine to turf) effected minor changes in ammonia oxidizer composition. Nitrosospira cluster 0 was observed only in older turfgrass systems (i.e., 23 and 95 years old); fine-scale differences within Nitrosospira cluster 3 were seen between native pines and turf. Further investigations are needed to elucidate the ecological implications of the compositional differences.

  1. Niche specialization of terrestrial archaeal ammonia oxidizers.

    PubMed

    Gubry-Rangin, Cécile; Hai, Brigitte; Quince, Christopher; Engel, Marion; Thomson, Bruce C; James, Phillip; Schloter, Michael; Griffiths, Robert I; Prosser, James I; Nicol, Graeme W

    2011-12-27

    Soil pH is a major determinant of microbial ecosystem processes and potentially a major driver of evolution, adaptation, and diversity of ammonia oxidizers, which control soil nitrification. Archaea are major components of soil microbial communities and contribute significantly to ammonia oxidation in some soils. To determine whether pH drives evolutionary adaptation and community structure of soil archaeal ammonia oxidizers, sequences of amoA, a key functional gene of ammonia oxidation, were examined in soils at global, regional, and local scales. Globally distributed database sequences clustered into 18 well-supported phylogenetic lineages that dominated specific soil pH ranges classified as acidic (pH <5), acido-neutral (5 ≤ pH <7), or alkalinophilic (pH ≥ 7). To determine whether patterns were reproduced at regional and local scales, amoA gene fragments were amplified from DNA extracted from 47 soils in the United Kingdom (pH 3.5-8.7), including a pH-gradient formed by seven soils at a single site (pH 4.5-7.5). High-throughput sequencing and analysis of amoA gene fragments identified an additional, previously undiscovered phylogenetic lineage and revealed similar pH-associated distribution patterns at global, regional, and local scales, which were most evident for the five most abundant clusters. Archaeal amoA abundance and diversity increased with soil pH, which was the only physicochemical characteristic measured that significantly influenced community structure. These results suggest evolution based on specific adaptations to soil pH and niche specialization, resulting in a global distribution of archaeal lineages that have important consequences for soil ecosystem function and nitrogen cycling.

  2. Niche specialization of terrestrial archaeal ammonia oxidizers

    PubMed Central

    Gubry-Rangin, Cécile; Hai, Brigitte; Quince, Christopher; Engel, Marion; Thomson, Bruce C.; James, Phillip; Schloter, Michael; Griffiths, Robert I.; Prosser, James I.; Nicol, Graeme W.

    2011-01-01

    Soil pH is a major determinant of microbial ecosystem processes and potentially a major driver of evolution, adaptation, and diversity of ammonia oxidizers, which control soil nitrification. Archaea are major components of soil microbial communities and contribute significantly to ammonia oxidation in some soils. To determine whether pH drives evolutionary adaptation and community structure of soil archaeal ammonia oxidizers, sequences of amoA, a key functional gene of ammonia oxidation, were examined in soils at global, regional, and local scales. Globally distributed database sequences clustered into 18 well-supported phylogenetic lineages that dominated specific soil pH ranges classified as acidic (pH <5), acido-neutral (5≤ pH <7), or alkalinophilic (pH ≥7). To determine whether patterns were reproduced at regional and local scales, amoA gene fragments were amplified from DNA extracted from 47 soils in the United Kingdom (pH 3.5–8.7), including a pH-gradient formed by seven soils at a single site (pH 4.5–7.5). High-throughput sequencing and analysis of amoA gene fragments identified an additional, previously undiscovered phylogenetic lineage and revealed similar pH-associated distribution patterns at global, regional, and local scales, which were most evident for the five most abundant clusters. Archaeal amoA abundance and diversity increased with soil pH, which was the only physicochemical characteristic measured that significantly influenced community structure. These results suggest evolution based on specific adaptations to soil pH and niche specialization, resulting in a global distribution of archaeal lineages that have important consequences for soil ecosystem function and nitrogen cycling. PMID:22158986

  3. Identifying Potential Mechanisms Enabling Acidophily in the Ammonia-Oxidizing Archaeon "Candidatus Nitrosotalea devanaterra".

    PubMed

    Lehtovirta-Morley, Laura E; Sayavedra-Soto, Luis A; Gallois, Nicolas; Schouten, Stefan; Stein, Lisa Y; Prosser, James I; Nicol, Graeme W

    2016-05-01

    Ammonia oxidation is the first and rate-limiting step in nitrification and is dominated by two distinct groups of microorganisms in soil: ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB). AOA are often more abundant than AOB and dominate activity in acid soils. The mechanism of ammonia oxidation under acidic conditions has been a long-standing paradox. While high rates of ammonia oxidation are frequently measured in acid soils, cultivated ammonia oxidizers grew only at near-neutral pH when grown in standard laboratory culture. Although a number of mechanisms have been demonstrated to enable neutrophilic AOB growth at low pH in the laboratory, these have not been demonstrated in soil, and the recent cultivation of the obligately acidophilic ammonia oxidizer "Candidatus Nitrosotalea devanaterra" provides a more parsimonious explanation for the observed high rates of activity. Analysis of the sequenced genome, transcriptional activity, and lipid content of "Ca Nitrosotalea devanaterra" reveals that previously proposed mechanisms used by AOB for growth at low pH are not essential for archaeal ammonia oxidation in acidic environments. Instead, the genome indicates that "Ca Nitrosotalea devanaterra" contains genes encoding both a predicted high-affinity substrate acquisition system and potential pH homeostasis mechanisms absent in neutrophilic AOA. Analysis of mRNA revealed that candidate genes encoding the proposed homeostasis mechanisms were all expressed during acidophilic growth, and lipid profiling by high-performance liquid chromatography-mass spectrometry (HPLC-MS) demonstrated that the membrane lipids of "Ca Nitrosotalea devanaterra" were not dominated by crenarchaeol, as found in neutrophilic AOA. This study for the first time describes a genome of an obligately acidophilic ammonia oxidizer and identifies potential mechanisms enabling this unique phenotype for future biochemical characterization. Copyright © 2016 Lehtovirta-Morley et al.

  4. Ammonia-oxidizing bacteria dominate ammonia oxidation in a full-scale wastewater treatment plant revealed by DNA-based stable isotope probing.

    PubMed

    Pan, Kai-Ling; Gao, Jing-Feng; Li, Hong-Yu; Fan, Xiao-Yan; Li, Ding-Chang; Jiang, Hao

    2018-05-01

    A full-scale wastewater treatment plant (WWTP) with three separate treatment processes was selected to investigate the effects of seasonality and treatment process on the community structures of ammonia-oxidizing archaea (AOA) and bacteria (AOB). And then DNA-based stable isotope probing (DNA-SIP) was applied to explore the active ammonia oxidizers. The results of high-throughput sequencing indicated that treatment processes varied AOB communities rather than AOA communities. AOA slightly outnumbered AOB in most of the samples, whose abundance was significantly correlated with temperature. DNA-SIP results showed that the majority of AOB amoA gene was labeled by 13 C-substrate, while just a small amount of AOA amoA gene was labeled. As revealed by high-throughput sequencing of heavy DNA, Nitrosomonadaceae-like AOB, Nitrosomonas sp. NP1, Nitrosomonas oligotropha and Nitrosomonas marina were the active AOB, and Nitrososphaera viennensis dominated the active AOA. The results indicated that AOB, not AOA, dominated active ammonia oxidation in the test WWTP. Copyright © 2018 Elsevier Ltd. All rights reserved.

  5. Cultivation of an obligate acidophilic ammonia oxidizer from a nitrifying acid soil.

    PubMed

    Lehtovirta-Morley, Laura E; Stoecker, Kilian; Vilcinskas, Andreas; Prosser, James I; Nicol, Graeme W

    2011-09-20

    Nitrification is a fundamental component of the global nitrogen cycle and leads to significant fertilizer loss and atmospheric and groundwater pollution. Nitrification rates in acidic soils (pH < 5.5), which comprise 30% of the world's soils, equal or exceed those of neutral soils. Paradoxically, autotrophic ammonia oxidizing bacteria and archaea, which perform the first stage in nitrification, demonstrate little or no growth in suspended liquid culture below pH 6.5, at which ammonia availability is reduced by ionization. Here we report the discovery and cultivation of a chemolithotrophic, obligately acidophilic thaumarchaeal ammonia oxidizer, "Candidatus Nitrosotalea devanaterra," from an acidic agricultural soil. Phylogenetic analysis places the organism within a previously uncultivated thaumarchaeal lineage that has been observed in acidic soils. Growth of the organism is optimal in the pH range 4 to 5 and is restricted to the pH range 4 to 5.5, unlike all previously cultivated ammonia oxidizers. Growth of this organism and associated ammonia oxidation and autotrophy also occur during nitrification in soil at pH 4.5. The discovery of Nitrosotalea devanaterra provides a previously unsuspected explanation for high rates of nitrification in acidic soils, and confirms the vital role that thaumarchaea play in terrestrial nitrogen cycling. Growth at extremely low ammonia concentration (0.18 nM) also challenges accepted views on ammonia uptake and metabolism and indicates novel mechanisms for ammonia oxidation at low pH.

  6. Cultivation of an obligate acidophilic ammonia oxidizer from a nitrifying acid soil

    PubMed Central

    Lehtovirta-Morley, Laura E.; Stoecker, Kilian; Vilcinskas, Andreas; Prosser, James I.; Nicol, Graeme W.

    2011-01-01

    Nitrification is a fundamental component of the global nitrogen cycle and leads to significant fertilizer loss and atmospheric and groundwater pollution. Nitrification rates in acidic soils (pH < 5.5), which comprise 30% of the world's soils, equal or exceed those of neutral soils. Paradoxically, autotrophic ammonia oxidizing bacteria and archaea, which perform the first stage in nitrification, demonstrate little or no growth in suspended liquid culture below pH 6.5, at which ammonia availability is reduced by ionization. Here we report the discovery and cultivation of a chemolithotrophic, obligately acidophilic thaumarchaeal ammonia oxidizer, “Candidatus Nitrosotalea devanaterra,” from an acidic agricultural soil. Phylogenetic analysis places the organism within a previously uncultivated thaumarchaeal lineage that has been observed in acidic soils. Growth of the organism is optimal in the pH range 4 to 5 and is restricted to the pH range 4 to 5.5, unlike all previously cultivated ammonia oxidizers. Growth of this organism and associated ammonia oxidation and autotrophy also occur during nitrification in soil at pH 4.5. The discovery of Nitrosotalea devanaterra provides a previously unsuspected explanation for high rates of nitrification in acidic soils, and confirms the vital role that thaumarchaea play in terrestrial nitrogen cycling. Growth at extremely low ammonia concentration (0.18 nM) also challenges accepted views on ammonia uptake and metabolism and indicates novel mechanisms for ammonia oxidation at low pH. PMID:21896746

  7. Aerobic methanol-oxidizing bacteria in soil.

    PubMed

    Kolb, Steffen

    2009-11-01

    Methanol is an atmospheric compound that is primarily released from plant polymers and impacts ozone formation. The global methanol emission rate from terrestrial ecosystems is of the same order of magnitude (4.9 x 10(12) mol year(-1)) as that of methane (10 x 10(12) mol year(-1)). The major proportion of the annual plant-released methanol does not enter the atmosphere, but may be reoxidized by biological methanol oxidation, which is catalyzed by methanol-oxidizing prokaryotes. Fifty-six aerobic methanol-oxidizing species have been isolated from soils. These methylotrophs belong to the Alpha-, Beta-, and Gammaproteobacteria, Verrucomicrobia, Firmicutes, and Actinobacteria. Their ecological niches are determined by oxygen and methanol concentration, temperature, pH, the capability to utilize nitrate as an electron acceptor, and the spectrum of nitrogen sources and utilizable multicarbon substrates. Recently discovered interactions with eukaryotes indicate that their ecological niches may not solely be defined by physicochemical parameters. Nonetheless, there are still gaps in knowledge; based on global methanol budgets, methanol oxidation in soil is important, but has not been addressed adequately by biogeochemical studies. Ratios of above-ground and soil-internal methanol oxidation are not known. The contribution to methanol-oxidation by aerobic and anaerobic methylotrophs in situ also needs further research.

  8. Ammonia-oxidizing microbial communities in reactors with efficient nitrification at low-dissolved oxygen

    PubMed Central

    Fitzgerald, Colin M.; Camejo, Pamela; Oshlag, J. Zachary; Noguera, Daniel R.

    2015-01-01

    Ammonia-oxidizing microbial communities involved in ammonia oxidation under low dissolved oxygen (DO) conditions (<0.3 mg/L) were investigated using chemostat reactors. One lab-scale reactor (NS_LowDO) was seeded with sludge from a full-scale wastewater treatment plant (WWTP) not adapted to low-DO nitrification, while a second reactor (JP_LowDO) was seeded with sludge from a full-scale WWTP already achieving low-DO nitrifiaction. The experimental evidence from quantitative PCR, rDNA tag pyrosequencing, and fluorescence in situ hybridization (FISH) suggested that ammonia-oxidizing bacteria (AOB) in the Nitrosomonas genus were responsible for low-DO nitrification in the NS_LowDO reactor, whereas in the JP_LowDO reactor nitrification was not associated with any known ammonia-oxidizing prokaryote. Neither reactor had a significant population of ammonia-oxidizing archaea (AOA) or anaerobic ammonium oxidation (anammox) organisms. Organisms isolated from JP_LowDO were capable of autotrophic and heterotrophic ammonia utilization, albeit without stoichiometric accumulation of nitrite or nitrate. Based on the experimental evidence we propose that Pseudomonas, Xanthomonadaceae, Rhodococcus, and Sphingomonas are involved in nitrification under low-DO conditions. PMID:25506762

  9. Ammonia oxidation, denitrification and dissimilatory nitrate reduction to ammonium in two US Great Basin hot springs with abundant ammonia-oxidizing archaea.

    PubMed

    Dodsworth, Jeremy A; Hungate, Bruce A; Hedlund, Brian P

    2011-08-01

    Many thermophiles catalyse free energy-yielding redox reactions involving nitrogenous compounds; however, little is known about these processes in natural thermal environments. Rates of ammonia oxidation, denitrification and dissimilatory nitrate reduction to ammonium (DNRA) were measured in source water and sediments of two ≈ 80°C springs in the US Great Basin. Ammonia oxidation and denitrification occurred mainly in sediments. Ammonia oxidation rates measured using (15)N-NO(3)(-) pool dilution ranged from 5.5 ± 0.8 to 8.6 ± 0.9 nmol N g(-1) h(-1) and were unaffected or only mildly stimulated by amendment with NH(4) Cl. Denitrification rates measured using acetylene block ranged from 15.8 ± 0.7 to 51 ± 12 nmol N g(-1) h(-1) and were stimulated by amendment with NO(3)(-) and complex organic compounds. The DNRA rate in one spring sediment measured using an (15)N-NO(3)(-) tracer was 315 ± 48 nmol N g(-1) h(-1). Both springs harboured distinct planktonic and sediment microbial communities. Close relatives of the autotrophic, ammonia-oxidizing archaeon 'Candidatus Nitrosocaldus yellowstonii' represented the most abundant OTU in both spring sediments by 16S rRNA gene pyrotag analysis. Quantitative PCR (qPCR) indicated that 'Ca. N. yellowstonii'amoA and 16S rRNA genes were present at 3.5-3.9 × 10(8) and 6.4-9.0 × 10(8) copies g(-1) sediment. Potential denitrifiers included members of the Aquificales and Thermales. Thermus spp. comprised <1% of 16S rRNA gene pyrotags in both sediments and qPCR for T. thermophilus narG revealed sediment populations of 1.3-1.7 × 10(6) copies g(-1) sediment. These data indicate a highly active nitrogen cycle (N-cycle) in these springs and suggest that ammonia oxidation may be a major source of energy fuelling primary production. © 2011 Society for Applied Microbiology and Blackwell Publishing Ltd.

  10. Bioturbation determines the response of benthic ammonia-oxidizing microorganisms to ocean acidification

    PubMed Central

    Laverock, B.; Kitidis, V.; Tait, K.; Gilbert, J. A.; Osborn, A. M.; Widdicombe, S.

    2013-01-01

    Ocean acidification (OA), caused by the dissolution of increasing concentrations of atmospheric carbon dioxide (CO2) in seawater, is projected to cause significant changes to marine ecology and biogeochemistry. Potential impacts on the microbially driven cycling of nitrogen are of particular concern. Specifically, under seawater pH levels approximating future OA scenarios, rates of ammonia oxidation (the rate-limiting first step of the nitrification pathway) have been shown to dramatically decrease in seawater, but not in underlying sediments. However, no prior study has considered the interactive effects of microbial ammonia oxidation and macrofaunal bioturbation activity, which can enhance nitrogen transformation rates. Using experimental mesocosms, we investigated the responses to OA of ammonia oxidizing microorganisms inhabiting surface sediments and sediments within burrow walls of the mud shrimp Upogebia deltaura. Seawater was acidified to one of four target pH values (pHT 7.90, 7.70, 7.35 and 6.80) in comparison with a control (pHT 8.10). At pHT 8.10, ammonia oxidation rates in burrow wall sediments were, on average, fivefold greater than in surface sediments. However, at all acidified pH values (pH ≤ 7.90), ammonia oxidation rates in burrow sediments were significantly inhibited (by 79–97%; p < 0.01), whereas rates in surface sediments were unaffected. Both bacterial and archaeal abundances increased significantly as pHT declined; by contrast, relative abundances of bacterial and archaeal ammonia oxidation (amoA) genes did not vary. This research suggests that OA could cause substantial reductions in total benthic ammonia oxidation rates in coastal bioturbated sediments, leading to corresponding changes in coupled nitrogen cycling between the benthic and pelagic realms. PMID:23980243

  11. Fabrication of highly selective tungsten oxide ammonia sensors

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Llobet, E.; Molas, G.; Molinas, P.

    Tungsten oxide is shown to be a very promising material for the fabrication of highly selective ammonia sensors. Films of WO{sub 3} were deposited onto a silicon substrate by means of the drop-coating method. Then, the films were annealed in dry air at two different temperatures (300 and 400 C). X-ray photoelectron spectroscopy was used to investigate the composition of the films. Tungsten appeared both in WO{sub 2} and WO{sub 3} oxidation states, but the second state was clearly dominant. Scanning electron microscopy results showed that the oxide was amorphous or nanocrystalline. The WO{sub 3}-based devices were sensitive to ammoniamore » vapors when operated between 250 and 350 C. The optimal operating temperature for the highest sensitivity to ammonia was 300 C. Furthermore, when the devices were operated at 300 C, their sensitivity to other reducing species such as ethanol, methane, toluene, and water vapor was significantly lower, and this resulted in a high selectivity to ammonia. A model for the sensing mechanisms of the fabricated sensors is proposed.« less

  12. Ammonia release method for depositing metal oxides

    DOEpatents

    Silver, Gary L.; Martin, Frank S.

    1994-12-13

    A method of depositing metal oxides on substrates which is indifferent to the electrochemical properties of the substrates and which comprises forming ammine complexes containing metal ions and thereafter effecting removal of ammonia from the ammine complexes so as to permit slow precipitation and deposition of metal oxide on the substrates.

  13. Ammonia oxidation coupled to CO2 fixation by archaea and bacteria in an agricultural soil.

    PubMed

    Pratscher, Jennifer; Dumont, Marc G; Conrad, Ralf

    2011-03-08

    Ammonia oxidation is an essential part of the global nitrogen cycling and was long thought to be driven only by bacteria. Recent findings expanded this pathway also to the archaea. However, most questions concerning the metabolism of ammonia-oxidizing archaea, such as ammonia oxidation and potential CO(2) fixation, remain open, especially for terrestrial environments. Here, we investigated the activity of ammonia-oxidizing archaea and bacteria in an agricultural soil by comparison of RNA- and DNA-stable isotope probing (SIP). RNA-SIP demonstrated a highly dynamic and diverse community involved in CO(2) fixation and carbon assimilation coupled to ammonia oxidation. DNA-SIP showed growth of the ammonia-oxidizing bacteria but not of archaea. Furthermore, the analysis of labeled RNA found transcripts of the archaeal acetyl-CoA/propionyl-CoA carboxylase (accA/pccB) to be expressed and labeled. These findings strongly suggest that ammonia-oxidizing archaeal groups in soil autotrophically fix CO(2) using the 3-hydroxypropionate-4-hydroxybutyrate cycle, one of the two pathways recently identified for CO(2) fixation in Crenarchaeota. Catalyzed reporter deposition (CARD)-FISH targeting the gene encoding subunit A of ammonia monooxygenase (amoA) mRNA and 16S rRNA of archaea also revealed ammonia-oxidizing archaea to be numerically relevant among the archaea in this soil. Our results demonstrate a diverse and dynamic contribution of ammonia-oxidizing archaea in soil to nitrification and CO(2) assimilation and that their importance to the overall archaeal community might be larger than previously thought.

  14. Ammonia oxidation coupled to CO2 fixation by archaea and bacteria in an agricultural soil

    PubMed Central

    Pratscher, Jennifer; Dumont, Marc G.; Conrad, Ralf

    2011-01-01

    Ammonia oxidation is an essential part of the global nitrogen cycling and was long thought to be driven only by bacteria. Recent findings expanded this pathway also to the archaea. However, most questions concerning the metabolism of ammonia-oxidizing archaea, such as ammonia oxidation and potential CO2 fixation, remain open, especially for terrestrial environments. Here, we investigated the activity of ammonia-oxidizing archaea and bacteria in an agricultural soil by comparison of RNA- and DNA-stable isotope probing (SIP). RNA-SIP demonstrated a highly dynamic and diverse community involved in CO2 fixation and carbon assimilation coupled to ammonia oxidation. DNA-SIP showed growth of the ammonia-oxidizing bacteria but not of archaea. Furthermore, the analysis of labeled RNA found transcripts of the archaeal acetyl-CoA/propionyl-CoA carboxylase (accA/pccB) to be expressed and labeled. These findings strongly suggest that ammonia-oxidizing archaeal groups in soil autotrophically fix CO2 using the 3-hydroxypropionate–4-hydroxybutyrate cycle, one of the two pathways recently identified for CO2 fixation in Crenarchaeota. Catalyzed reporter deposition (CARD)-FISH targeting the gene encoding subunit A of ammonia monooxygenase (amoA) mRNA and 16S rRNA of archaea also revealed ammonia-oxidizing archaea to be numerically relevant among the archaea in this soil. Our results demonstrate a diverse and dynamic contribution of ammonia-oxidizing archaea in soil to nitrification and CO2 assimilation and that their importance to the overall archaeal community might be larger than previously thought. PMID:21368116

  15. Co(salophen)-Catalyzed Aerobic Oxidation of p-Hydroquinone: Mechanism and Implications for Aerobic Oxidation Catalysis

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Anson, Colin W.; Ghosh, Soumya; Hammes-Schiffer, Sharon

    2016-03-30

    Macrocyclic metal complexes and p-benzoquinones are commonly used as co-catalytic redox mediators in aerobic oxidation reactions. In an effort to gain insight into the mechanism and energetic efficiency of these reactions, we investigated Co(salophen)-catalyzed aerobic oxidation of p-hydroquinone. Kinetic and spectroscopic data suggest that the catalyst resting-state consists of an equilibrium between a CoII(salophen) complex, a CoIII-superoxide adduct, and a hydrogen-bonded adduct between the hydroquinone and the CoIII–O2 species. The kinetic data, together with density functional theory data, suggest that the turnover-limiting step features proton-coupled electron transfer from a semi-hydroquinone species and a CoIII-hydroperoxide intermediate. Additional experimental and computational datamore » suggest that a coordinated H2O2 intermediate oxidizes a second equivalent of hydroquinone. This research was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center, funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences. The NSF provided partial support for the EPR instrumentation (NSF CHE-0741901).« less

  16. Identifying Potential Mechanisms Enabling Acidophily in the Ammonia-Oxidizing Archaeon “Candidatus Nitrosotalea devanaterra”

    PubMed Central

    Sayavedra-Soto, Luis A.; Gallois, Nicolas; Schouten, Stefan; Stein, Lisa Y.; Prosser, James I.; Nicol, Graeme W.

    2016-01-01

    Ammonia oxidation is the first and rate-limiting step in nitrification and is dominated by two distinct groups of microorganisms in soil: ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB). AOA are often more abundant than AOB and dominate activity in acid soils. The mechanism of ammonia oxidation under acidic conditions has been a long-standing paradox. While high rates of ammonia oxidation are frequently measured in acid soils, cultivated ammonia oxidizers grew only at near-neutral pH when grown in standard laboratory culture. Although a number of mechanisms have been demonstrated to enable neutrophilic AOB growth at low pH in the laboratory, these have not been demonstrated in soil, and the recent cultivation of the obligately acidophilic ammonia oxidizer “Candidatus Nitrosotalea devanaterra” provides a more parsimonious explanation for the observed high rates of activity. Analysis of the sequenced genome, transcriptional activity, and lipid content of “Ca. Nitrosotalea devanaterra” reveals that previously proposed mechanisms used by AOB for growth at low pH are not essential for archaeal ammonia oxidation in acidic environments. Instead, the genome indicates that “Ca. Nitrosotalea devanaterra” contains genes encoding both a predicted high-affinity substrate acquisition system and potential pH homeostasis mechanisms absent in neutrophilic AOA. Analysis of mRNA revealed that candidate genes encoding the proposed homeostasis mechanisms were all expressed during acidophilic growth, and lipid profiling by high-performance liquid chromatography–mass spectrometry (HPLC-MS) demonstrated that the membrane lipids of “Ca. Nitrosotalea devanaterra” were not dominated by crenarchaeol, as found in neutrophilic AOA. This study for the first time describes a genome of an obligately acidophilic ammonia oxidizer and identifies potential mechanisms enabling this unique phenotype for future biochemical characterization. PMID:26896134

  17. Substrate and nutrient limitation of ammonia-oxidizing bacteria and archaea in temperate forest soil

    Treesearch

    J.S. Norman; J.E. Barrett

    2014-01-01

    Ammonia-oxidizing microbes control the rate-limiting step of nitrification, a critical ecosystem process, which affects retention and mobility of nitrogen in soil ecosystems. This study investigated substrate (NH4þ) and nutrient (K and P) limitation of ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) in temperate forest soils at Coweeta Hydrologic...

  18. Links between ammonia oxidizer species composition, functional diversity and nitrification kinetics in grassland soils.

    PubMed

    Webster, Gordon; Embley, T Martin; Freitag, Thomas E; Smith, Zena; Prosser, James I

    2005-05-01

    Molecular approaches have revealed considerable diversity and uncultured novelty in natural prokaryotic populations, but not direct links between the new genotypes detected and ecosystem processes. Here we describe the influence of the structure of communities of ammonia-oxidizing bacteria on nitrogen cycling in microcosms containing natural and managed grasslands and amended with artificial sheep urine, a major factor determining local ammonia concentrations in these environments. Nitrification kinetics were assessed by analysis of changes in urea, ammonia, nitrite and nitrate concentrations and ammonia oxidizer communities were characterized by analysis of 16S rRNA genes amplified from extracted DNA using ammonia oxidizer-specific primers. In natural soils, ammonia oxidizer community structure determined the delay preceding nitrification, which depended on the relative abundance of two Nitrosospira clusters, termed 3a and 3b. In batch cultures, pure culture and enrichment culture representatives of Nitrosospira 3a were sensitive to high ammonia concentration, while Nitrosospira cluster 3b representatives and Nitrosomonas europaea were tolerant. Delays in nitrification occurred in natural soils dominated by Nitrosospira cluster 3a and resulted from the time required for growth of low concentrations of Nitrosospira cluster 3b. In microcosms dominated by Nitrosospira cluster 3b and Nitrosomonas, no substantial delays were observed. In managed soils, no delays in nitrification were detected, regardless of initial ammonia oxidizer community structure, most probably resulting from higher ammonia oxidizer cell concentrations. The data therefore demonstrate a direct link between bacterial community structure, physiological diversity and ecosystem function.

  19. Ammonia release method for depositing metal oxides

    DOEpatents

    Silver, G.L.; Martin, F.S.

    1994-12-13

    A method is described for depositing metal oxides on substrates which is indifferent to the electrochemical properties of the substrates and which comprises forming ammine complexes containing metal ions and thereafter effecting removal of ammonia from the ammine complexes so as to permit slow precipitation and deposition of metal oxide on the substrates. 1 figure.

  20. [Ammonia-oxidizing archaea and their important roles in nitrogen biogeochemical cycling: a review].

    PubMed

    Liu, Jing-Jing; Wu, Wei-Xiang; Ding, Ying; Shi, De-Zhi; Chen, Ying-Xu

    2010-08-01

    As the first step of nitrification, ammonia oxidation is the key process in global nitrogen biogeochemical cycling. So far, the autotrophic ammonia-oxidizing bacteria (AOB) in the beta- and gamma-subgroups of proteobacteria have been considered as the most important contributors to ammonia oxidation, but the recent researches indicated that ammonia-oxidizing archaea (AOA) are widely distributed in various kinds of ecosystems and quantitatively predominant, playing important roles in the global nitrogen biogeochemical cycling. This paper reviewed the morphological, physiological, and ecological characteristics and the molecular phylogenies of AOA, and compared and analyzed the differences and similarities of the ammonia monooxygenase (AMO) and its encoding genes between AOA and AOB. In addition, the potential significant roles of AOA in nitrogen biogeochemical cycling in aquatic and terrestrial ecosystems were summarized, and the future research directions of AOA in applied ecology and environmental protection were put forward.

  1. A TEMPO-free copper-catalyzed aerobic oxidation of alcohols.

    PubMed

    Xu, Boran; Lumb, Jean-Philip; Arndtsen, Bruce A

    2015-03-27

    The copper-catalyzed aerobic oxidation of primary and secondary alcohols without an external N-oxide co-oxidant is described. The catalyst system is composed of a Cu/diamine complex inspired by the enzyme tyrosinase, along with dimethylaminopyridine (DMAP) or N-methylimidazole (NMI). The Cu catalyst system works without 2,2,6,6-tetramethyl-l-piperidinoxyl (TEMPO) at ambient pressure and temperature, and displays activity for un-activated secondary alcohols, which remain a challenging substrate for catalytic aerobic systems. Our work underscores the importance of finding alternative mechanistic pathways for alcohol oxidation, which complement Cu/TEMPO systems, and demonstrate, in this case, a preference for the oxidation of activated secondary over primary alcohols. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Combined anaerobic/aerobic digestion: effect of aerobic retention time on nitrogen and solids removal.

    PubMed

    Kim, Jongmin; Novak, John T

    2011-09-01

    A combined anaerobic/aerobic sludge digestion system was studied to determine the effect of aerobic solids retention time (SRT) on its solids and nitrogen removal efficiencies. After the anaerobic digester reached steady state, effluent from the anaerobic digester was fed to aerobic digesters that were operated at 2- to 5-day SRTs. The anaerobic system was fed with a mixture of primary and secondary sludge from a local municipal wastewater treatment plant. Both systems were fed once per a day. The aerobic reactor was continuously aerated with ambient air, maintaining dissolved oxygen level at 1.1 +/- 0.3 mg/L. At a 4-day or longer SRT, more than 11% additional volatile solids and 90% or greater ammonia were removed in the aerobic digester, while 32.8 mg-N/L or more nitrite/nitrate also was measured. Most total Kjeldahl nitrogen removal was via ammonia removal, while little organic nitrogen was removed in the aerobic digester.

  3. Activity of Cu-activated carbon fiber catalyst in wet oxidation of ammonia solution.

    PubMed

    Hung, Chang-Mao

    2009-07-30

    Aqueous solutions of 200-1000 mg/L of ammonia were oxidized in a trickle-bed reactor using Cu-activated carbon fiber (ACF) catalysts, which were prepared by incipient wet impregnation with aqueous solutions of copper nitrate that was deposited on ACF substrates. The results reveal that the conversion of ammonia by wet oxidation in the presence of Cu-ACF catalysts was a function of the metal loading weight ratio of the catalyst. The total conversion efficiency of ammonia was 95% during wet oxidation over the catalyst at 463 K at an oxygen partial pressure of 3.0 MPa. Moreover, the effect of the initial concentration of ammonia and the reaction temperature on the removal of ammonia from the effluent streams was also studied at a liquid space velocity of less than 3.0 h(-1).

  4. Biotransformation of Two Pharmaceuticals by the Ammonia-Oxidizing Archaeon Nitrososphaera gargensis

    PubMed Central

    2016-01-01

    The biotransformation of some micropollutants has previously been observed to be positively associated with ammonia oxidation activities and the transcript abundance of the archaeal ammonia monooxygenase gene (amoA) in nitrifying activated sludge. Given the increasing interest in and potential importance of ammonia-oxidizing archaea (AOA), we investigated the capabilities of an AOA pure culture, Nitrososphaera gargensis, to biotransform ten micropollutants belonging to three structurally similar groups (i.e., phenylureas, tertiary amides, and tertiary amines). N. gargensis was able to biotransform two of the tertiary amines, mianserin (MIA) and ranitidine (RAN), exhibiting similar compound specificity as two ammonia-oxidizing bacteria (AOB) strains that were tested for comparison. The same MIA and RAN biotransformation reactions were carried out by both the AOA and AOB strains. The major transformation product (TP) of MIA, α-oxo MIA was likely formed via a two-step oxidation reaction. The first hydroxylation step is typically catalyzed by monooxygenases. Three RAN TP candidates were identified from nontarget analysis. Their tentative structures and possible biotransformation pathways were proposed. The biotransformation of MIA and RAN only occurred when ammonia oxidation was active, suggesting cometabolic transformations. Consistently, a comparative proteomic analysis revealed no significant differential expression of any protein-encoding gene in N. gargensis grown on ammonium with MIA or RAN compared with standard cultivation on ammonium only. Taken together, this study provides first important insights regarding the roles played by AOA in micropollutant biotransformation. PMID:27046099

  5. Biotransformation of Two Pharmaceuticals by the Ammonia-Oxidizing Archaeon Nitrososphaera gargensis.

    PubMed

    Men, Yujie; Han, Ping; Helbling, Damian E; Jehmlich, Nico; Herbold, Craig; Gulde, Rebekka; Onnis-Hayden, Annalisa; Gu, April Z; Johnson, David R; Wagner, Michael; Fenner, Kathrin

    2016-05-03

    The biotransformation of some micropollutants has previously been observed to be positively associated with ammonia oxidation activities and the transcript abundance of the archaeal ammonia monooxygenase gene (amoA) in nitrifying activated sludge. Given the increasing interest in and potential importance of ammonia-oxidizing archaea (AOA), we investigated the capabilities of an AOA pure culture, Nitrososphaera gargensis, to biotransform ten micropollutants belonging to three structurally similar groups (i.e., phenylureas, tertiary amides, and tertiary amines). N. gargensis was able to biotransform two of the tertiary amines, mianserin (MIA) and ranitidine (RAN), exhibiting similar compound specificity as two ammonia-oxidizing bacteria (AOB) strains that were tested for comparison. The same MIA and RAN biotransformation reactions were carried out by both the AOA and AOB strains. The major transformation product (TP) of MIA, α-oxo MIA was likely formed via a two-step oxidation reaction. The first hydroxylation step is typically catalyzed by monooxygenases. Three RAN TP candidates were identified from nontarget analysis. Their tentative structures and possible biotransformation pathways were proposed. The biotransformation of MIA and RAN only occurred when ammonia oxidation was active, suggesting cometabolic transformations. Consistently, a comparative proteomic analysis revealed no significant differential expression of any protein-encoding gene in N. gargensis grown on ammonium with MIA or RAN compared with standard cultivation on ammonium only. Taken together, this study provides first important insights regarding the roles played by AOA in micropollutant biotransformation.

  6. Anti-Oxidative Defences Are Modulated Differentially in Three Freshwater Teleosts in Response to Ammonia-Induced Oxidative Stress

    PubMed Central

    Giblen, Terri; Zinta, Gaurav; De Rop, Michelle; Asard, Han; Blust, Ronny; De Boeck, Gudrun

    2014-01-01

    Oxidative stress and the antioxidant response induced by high environmental ammonia (HEA) were investigated in the liver and gills of three freshwater teleosts differing in their sensitivities to ammonia. The highly ammonia-sensitive salmonid Oncorhynchus mykiss (rainbow trout), the less ammonia sensitive cyprinid Cyprinus carpio (common carp) and the highly ammonia-resistant cyprinid Carassius auratus (goldfish) were exposed to 1 mM ammonia (as NH4HCO3) for 0 h (control), 3 h, 12 h, 24 h, 48 h, 84 h and 180 h. Results show that HEA exposure increased ammonia accumulation significantly in the liver of all the three fish species from 24 h–48 h onwards which was associated with an increment in oxidative stress, evidenced by elevation of xanthine oxidase activity and levels of hydrogen peroxide (H2O2) and malondialdehyde (MDA). Unlike in trout, H2O2 and MDA accumulation in carp and goldfish liver was restored to control levels (84 h–180 h); which was accompanied by a concomitant increase in superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase activity and reduced ascorbate content. Many of these defence parameters remained unaffected in trout liver, while components of the glutathione redox cycle (reduced glutathione, glutathione peroxidase and glutathione reductase) enhanced to a greater extent. The present findings suggest that trout rely mainly on glutathione dependent defensive mechanism while carp utilize SOD, CAT and ascorbate as anti-oxidative sentinels. Hepatic cells of goldfish appear to utilize each of these protective systems, and showed more effective anti-oxidative compensatory responses towards HEA than carp, while trout were least effective. The present work also indicates that HEA exposure resulted in a relatively mild oxidative stress in the gills of all three species. This probably explains the almost complete lack of anti-oxidative responses in branchial tissue. This research suggests that oxidative stress, as well as the antioxidant

  7. The inhibitory effects of free ammonia on ammonia oxidizing bacteria and nitrite oxidizing bacteria under anaerobic condition.

    PubMed

    Qian, Wenting; Peng, Yongzhen; Li, Xiyao; Zhang, Qiong; Ma, Bin

    2017-11-01

    The free ammonia (FA) inhibition on ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) under anaerobic condition was investigated in this study. The results indicated that NOB was more sensitive to the FA anaerobic treatment than AOB. The FA anaerobic inhibition on nitrifier gradually heightened with the increase of FA concentration. Accompanied with FA concentration increase from 0 to 16.82mgNH 3 -N·L -1 (the highest concentration adopted in this study), the activity of AOB reduced by 15.9%, while NOB decreased by 29.2%. After FA anaerobic treatment, nitrite was accumulated during nitrification. However, the nitrite accumulation disappeared on the sixth cycle of activity recovery tests with excessive aeration. Based on this result, a novel strategy for achieving nitritation is proposed, which involves recirculating a portion of the activated sludge through a side-line sludge treatment unit, where the sludge is subjected to treatment with FA under anaerobic condition. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Identification of Bacteria Responsible for Ammonia Oxidation in Freshwater Aquaria

    PubMed Central

    Burrell, Paul C.; Phalen, Carol M.; Hovanec, Timothy A.

    2001-01-01

    Culture enrichments and culture-independent molecular methods were employed to identify and confirm the presence of novel ammonia-oxidizing bacteria (AOB) in nitrifying freshwater aquaria. Reactors were seeded with biomass from freshwater nitrifying systems and enriched for AOB under various conditions of ammonia concentration. Surveys of cloned rRNA genes from the enrichments revealed four major strains of AOB which were phylogenetically related to the Nitrosomonas marina cluster, the Nitrosospira cluster, or the Nitrosomonas europaea-Nitrosococcus mobilis cluster of the β subdivision of the class Proteobacteria. Ammonia concentration in the reactors determined which AOB strain dominated in an enrichment. Oligonucleotide probes and PCR primer sets specific for the four AOB strains were developed and used to confirm the presence of the AOB strains in the enrichments. Enrichments of the AOB strains were added to newly established aquaria to determine their ability to accelerate the establishment of ammonia oxidation. Enrichments containing the Nitrosomonas marina-like AOB strain were most efficient at accelerating ammonia oxidation in newly established aquaria. Furthermore, if the Nitrosomonas marina-like AOB strain was present in the original enrichment, even one with other AOB, only the Nitrosomonas marina-like AOB strain was present in aquaria after nitrification was established. Nitrosomonas marina-like AOB were 2% or less of the cells detected by fluorescence in situ hybridization analysis in aquaria in which nitrification was well established. PMID:11722936

  9. Determination of Ammonia Oxidizing Bacteria and Nitrate Oxidizing Bacteria in Wastewater and Bioreactors

    NASA Technical Reports Server (NTRS)

    Francis, Somilez Asya

    2014-01-01

    The process of water purification has many different physical, chemical, and biological processes. One part of the biological process is the task of ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB). Both play critical roles in the treatment of wastewater by oxidizing toxic compounds. The broad term is nitrification, a naturally occurring process that is carried out by AOB and NOB by using oxidation to convert ammonia to nitrite and nitrite to nitrate. To monitor this biological activity, bacterial staining was performed on wastewater contained in inoculum tanks and biofilm samples from bioreactors. Using microscopy and qPCR, the purpose of this experiment was to determine if the population of AOB and NOB in wastewater and membrane bioreactors changed depending on temperature and hibernation conditions to determine the optimal parameters for AOB/NOB culture to effectively clean wastewater.

  10. Nitrification and the ammonia-oxidizing communities in the central Baltic Sea water column

    NASA Astrophysics Data System (ADS)

    Jäntti, Helena; Ward, Bess B.; Dippner, Joachim W.; Hietanen, Susanna

    2018-03-01

    The redoxclines that form between the oxic and anoxic water layers in the central Baltic Sea are sites of intensive nitrogen cycling. To gain better understanding of nitrification, we measured the biogeochemical properties along with potential nitrification rates and analyzed the assemblages of ammonia-oxidizing bacteria and archaea using functional gene microarrays. To estimate nitrification in the entire water column, we constructed a regression model for the nitrification rates and applied it to the conditions prevailing in the area in 2008-2012. The highest ammonia oxidation rates were found in a thin layer at the top of the redoxcline and the rates quickly decreased below detection limit when oxygen was exhausted. This is probably because extensive suboxic layers, which are known to harbor pelagic nitrification, are formed only for short periods after inflows in the Baltic Sea. The nitrification rates were some of the highest measured in the water columns, but the thickness of the layer where conditions were favorable for nitrification, was very small and it remained fairly stable between years. However, the depth of the nitrification layer varied substantially between years, particularly in the eastern Gotland Basin (EGB) due to turbulence in the water column. The ammonia oxidizer communities clustered differently between the eastern and western Gotland Basin (WGB) and the composition of ammonia-oxidizing assemblages correlated with the environmental variables. The ammonia oxidizer community composition was more even in the EGB, which may be related to physical instability of the redoxcline that does not allow predominance of a single archetype, whereas in the WGB, where the position of the redoxcline is more constant, the ammonia-oxidizing community was less even. Overall the ammonia-oxidizing communities in the Baltic Sea redoxclines were very evenly distributed compared to other marine environments where microarrays have been applied previously.

  11. An acid-tolerant ammonia-oxidizing γ-proteobacterium from soil

    PubMed Central

    Hayatsu, Masahito; Tago, Kanako; Uchiyama, Ikuo; Toyoda, Atsushi; Wang, Yong; Shimomura, Yumi; Okubo, Takashi; Kurisu, Futoshi; Hirono, Yuhei; Nonaka, Kunihiko; Akiyama, Hiroko; Itoh, Takehiko; Takami, Hideto

    2017-01-01

    Nitrification, the microbial oxidation of ammonia to nitrate via nitrite, occurs in a wide range of acidic soils. However, the ammonia-oxidizing bacteria (AOB) that have been isolated from soil to date are acid-sensitive. Here we report the isolation and characterization of an acid-adapted AOB from an acidic agricultural soil. The isolated AOB, strain TAO100, is classified within the Gammaproteobacteria based on phylogenetic characteristics. TAO100 can grow in the pH range of 5–7.5 and survive in highly acidic conditions until pH 2 by forming cell aggregates. Whereas all known gammaproteobacterial AOB (γ-AOB) species, which have been isolated from marine and saline aquatic environments, are halophiles, TAO100 is not phenotypically halophilic. Thus, TAO100 represents the first soil-originated and non-halophilic γ-AOB. The TAO100 genome is considerably smaller than those of other γ-AOB and lacks several genes associated with salt tolerance which are unnecessary for survival in soil. The ammonia monooxygenase subunit A gene of TAO100 and its transcript are higher in abundance than those of ammonia-oxidizing archaea and betaproteobacterial AOB in the strongly acidic soil. These results indicate that TAO100 plays an important role in the nitrification of acidic soils. Based on these results, we propose TAO100 as a novel species of a new genus, Candidatus Nitrosoglobus terrae. PMID:28072419

  12. An acid-tolerant ammonia-oxidizing γ-proteobacterium from soil.

    PubMed

    Hayatsu, Masahito; Tago, Kanako; Uchiyama, Ikuo; Toyoda, Atsushi; Wang, Yong; Shimomura, Yumi; Okubo, Takashi; Kurisu, Futoshi; Hirono, Yuhei; Nonaka, Kunihiko; Akiyama, Hiroko; Itoh, Takehiko; Takami, Hideto

    2017-05-01

    Nitrification, the microbial oxidation of ammonia to nitrate via nitrite, occurs in a wide range of acidic soils. However, the ammonia-oxidizing bacteria (AOB) that have been isolated from soil to date are acid-sensitive. Here we report the isolation and characterization of an acid-adapted AOB from an acidic agricultural soil. The isolated AOB, strain TAO100, is classified within the Gammaproteobacteria based on phylogenetic characteristics. TAO100 can grow in the pH range of 5-7.5 and survive in highly acidic conditions until pH 2 by forming cell aggregates. Whereas all known gammaproteobacterial AOB (γ-AOB) species, which have been isolated from marine and saline aquatic environments, are halophiles, TAO100 is not phenotypically halophilic. Thus, TAO100 represents the first soil-originated and non-halophilic γ-AOB. The TAO100 genome is considerably smaller than those of other γ-AOB and lacks several genes associated with salt tolerance which are unnecessary for survival in soil. The ammonia monooxygenase subunit A gene of TAO100 and its transcript are higher in abundance than those of ammonia-oxidizing archaea and betaproteobacterial AOB in the strongly acidic soil. These results indicate that TAO100 plays an important role in the nitrification of acidic soils. Based on these results, we propose TAO100 as a novel species of a new genus, Candidatus Nitrosoglobus terrae.

  13. Ecophysiology of an ammonia-oxidizing archaeon adapted to low-salinity habitats.

    PubMed

    Mosier, Annika C; Lund, Marie B; Francis, Christopher A

    2012-11-01

    Ammonia oxidation in marine and terrestrial ecosystems plays a pivotal role in the cycling of nitrogen and carbon. Recent discoveries have shown that ammonia-oxidizing archaea (AOA) are both abundant and diverse in these systems, yet very little is known about their physiology. Here we report a physiological analysis of a novel low-salinity-type AOA enriched from the San Francisco Bay estuary, Candidatus Nitrosoarchaeum limnia strain SFB1. N. limnia has a slower growth rate than Nitrosopumilus maritimus and Nitrososphaera viennensis EN76, the only pure AOA isolates described to date, but the growth rate is comparable to the growth of marine AOA enrichment cultures. The growth rate only slightly decreased when N. limnia was grown under lower-oxygen conditions (5.5 % oxygen in the headspace). Although N. limnia was capable of growth at 75 % of seawater salinity, there was a longer lag time, incomplete oxidation of ammonia to nitrite, and slower overall growth rate. Allylthiourea (ATU) only partially inhibited growth and ammonia oxidation by N. limnia at concentrations known to completely inhibit bacterial ammonia oxidation. Using electron microscopy, we confirmed the presence of flagella as suggested by various flagellar biosynthesis genes in the N. limnia genome. We demonstrate that N. limnia is representative of a low-salinity estuarine AOA ecotype and that more than 85 % of its proteins have highest identity to other coastal and estuarine metagenomic sequences. Our findings further highlight the physiology of N. limnia and help explain its ecological adaptation to low-salinity niches.

  14. Responses of the terrestrial ammonia-oxidizing archaeon Ca. Nitrososphaera viennensis and the ammonia-oxidizing bacterium Nitrosospira multiformis to nitrification inhibitors.

    PubMed

    Shen, Tianlin; Stieglmeier, Michaela; Dai, Jiulan; Urich, Tim; Schleper, Christa

    2013-07-01

    Nitrification inhibitors have been used for decades to improve nitrogen fertilizer utilization in farmland. However, their effect on ammonia-oxidizing Archaea (AOA) in soil is little explored. Here, we compared the impact of diverse inhibitors on nitrification activity of the soil archaeon Ca. Nitrososphaera viennensis EN76 and compared it to that of the ammonia-oxidizing bacterium (AOB) Nitrosospira multiformis. Allylthiourea, amidinothiourea, and dicyandiamide (DCD) inhibited ammonia oxidation in cultures of both N. multiformis and N. viennensis, but the effect on N. viennensis was markedly lower. In particular, the effective concentration 50 (EC50) of allylthiourea was 1000 times higher for the AOA culture. Among the tested nitrification inhibitors, DCD was the least potent against N. viennensis. Nitrapyrin had at the maximal soluble concentration only a very weak inhibitory effect on the AOB N. multiformis, but showed a moderate effect on the AOA. The antibiotic sulfathiazole inhibited the bacterium, but barely affected the archaeon. Only the NO-scavenger carboxy-PTIO had a strong inhibitory effect on the archaeon, but had little effect on the bacterium in the concentrations tested. Our results reflect the fundamental metabolic and cellular differences of AOA and AOB and will be useful for future applications of inhibitors aimed at distinguishing activities of AOA and AOB in soil environments. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  15. Degradation of halogenated aliphatic compounds by the ammonia- oxidizing bacterium Nitrosomonas europaea.

    PubMed

    Vannelli, T; Logan, M; Arciero, D M; Hooper, A B

    1990-04-01

    Suspensions of Nitrosomonas europaea catalyzed the ammonia-stimulated aerobic transformation of the halogenated aliphatic compounds dichloromethane, dibromomethane, trichloromethane (chloroform), bromoethane, 1,2-dibromoethane (ethylene dibromide), 1,1,2-trichloroethane, 1,1,1-trichloroethane, monochloroethylene (vinyl chloride), gem-dichloroethylene, cis- and trans-dichloroethylene, cis-dibromoethylene, trichloroethylene, and 1,2,3-trichloropropane, Tetrachloromethane (carbon tetrachloride), tetrachloroethylene (perchloroethylene), and trans-dibromoethylene were not degraded.

  16. Trichloroethylene biodegradation by mesophilic and psychrophilic ammonia oxidizers and methanotrophs in groundwater microcosms.

    PubMed Central

    Moran, B N; Hickey, W J

    1997-01-01

    This study investigated the efficiency of methane and ammonium for stimulating trichloroethylene (TCE) biodegradation in groundwater microcosms (flasks and batch exchange columns) at a psychrophilic temperature (12 degrees C) typical of shallow aquifers in the northern United States or a mesophilic temperature (24 degrees C) representative of most laboratory experiments. After 140 days, TCE biodegradation rates by ammonia oxidizers and methanotrophs in mesophilic flask microcosms were similar (8 to 10 nmol day-1), but [14C]TCE mineralization (biodegradation to 14CO2) by ammonia oxidizers was significantly greater than that by methanotrophs (63 versus 53%). Under psychrophilic conditions, [14C]TCE mineralization in flask systems by ammonia oxidizers and methanotrophs was reduced to 12 and 5%, respectively. In mesophilic batch exchange columns, average TCE biodegradation rates for methanotrophs (900 nmol liter-1 day-1) were not significantly different from those of ammonia oxidizers (775 nmol liter-1 day-1). Psychrophilic TCE biodegradation rates in the columns were similar with both biostimulants and averaged 145 nmol liter-1 day-1. Methanotroph biostimulation was most adversely affected by low temperatures. At 12 degrees C, the biodegradation efficiencies (TCE degradation normalized to microbial activity) of methanotrophs and ammonia oxidizers decreased by factors of 2.6 and 1.6, respectively, relative to their biodegradation efficiencies at 24 degrees C. Collectively, these experiments demonstrated that in situ bioremediation of TCE is feasible at the psychrophilic temperatures common in surficial aquifers in the northern United States and that for such applications biostimulation of ammonia oxidizers could be more effective than has been previously reported. PMID:9327550

  17. Community structure analysis of soil ammonia oxidizers during vegetation restoration in southwest China.

    PubMed

    Liang, Yueming; He, Xunyang; Liang, Shichu; Zhang, Wei; Chen, Xiangbi; Feng, Shuzheng; Su, Yirong

    2014-03-01

    Soil ammonia oxidizers play a critical role in nitrogen cycling and ecological restoration. The composition and structure of soil ammonia oxidizers and their impacting factors were studied in four typical ecosystem soils, tussock (T), shrub (S), secondary forest (SF), and primary forest (PF), during vegetation restoration in the Karst region of Southwest China. The composition and structure of the ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) communities were characterized by sequencing the amoA and arch-amoA genes, respectively. The diversity of soil ammonia oxidizers (except in S) and plant Shannon diversity index gradually increased with vegetation restoration, and the ammonia oxidizer communities differed significantly (p < 0.001). Amplicons of AOA from the Nitrososphaera cluster dominated all four ecosystem soils. AOB Nitrosospira cluster 3b only appeared in PF and SF soils, while Nitrosospira cluster 3a species were found in all soils. Changes in AOB paralleled the changes in soil ammonium content that occurred with vegetation restoration. Redundancy analysis showed that the distribution of dominant AOB species was linked to pH, soil urease activity, and soil C/N ratio, whereas the distribution of dominant AOA species was mainly influenced by litter nitrogen content and C/N ratio. These results suggested that the composition and structure of the AOB community were more sensitive to changes in vegetation and soil ammonium content, and may be an important indicator of nitrogen availability in Karst ecosystem soils. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. A zinc oxide nanorod ammonia microsensor integrated with a readout circuit on-a-chip.

    PubMed

    Yang, Ming-Zhi; Dai, Ching-Liang; Wu, Chyan-Chyi

    2011-01-01

    A zinc oxide nanorod ammonia microsensor integrated with a readout circuit on-a-chip fabricated using the commercial 0.35 μm complementary metal oxide semiconductor (CMOS) process was investigated. The structure of the ammonia sensor is composed of a sensitive film and polysilicon electrodes. The ammonia sensor requires a post-process to etch the sacrificial layer, and to coat the sensitive film on the polysilicon electrodes. The sensitive film that is prepared by a hydrothermal method is made of zinc oxide. The sensor resistance changes when the sensitive film adsorbs or desorbs ammonia gas. The readout circuit is used to convert the sensor resistance into the voltage output. Experiments show that the ammonia sensor has a sensitivity of about 1.5 mV/ppm at room temperature.

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

    PubMed

    Chandran, Kartik; Stein, Lisa Y; Klotz, Martin G; van Loosdrecht, Mark C M

    2011-12-01

    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.

  20. Relative contribution of ammonia oxidizing bacteria and other members of nitrifying activated sludge communities to micropollutant biotransformation.

    PubMed

    Men, Yujie; Achermann, Stefan; Helbling, Damian E; Johnson, David R; Fenner, Kathrin

    2017-02-01

    Improved micropollutant (MP) biotransformation during biological wastewater treatment has been associated with high ammonia oxidation activities, suggesting co-metabolic biotransformation by ammonia oxidizing bacteria as an underlying mechanism. The goal of this study was to clarify the contribution of ammonia oxidizing bacteria to increased MP degradation in nitrifying activated sludge (NAS) communities using a series of inhibition experiments. To this end, we treated a NAS community with two different ammonia oxidation inhibitors, namely octyne (OCT), a mechanistic inhibitor that covalently binds to ammonia monooxygenases, and allylthiourea (ATU), a copper chelator that depletes copper ions from the active center of ammonia monooxygenases. We investigated the biotransformation of 79 structurally different MPs by the inhibitor-treated and untreated sludge communities. Fifty-five compounds exhibited over 20% removal in the untreated control after a 46 h-incubation. Of these, 31 compounds were significantly inhibited by either ATU and/or OCT. For 17 of the 31 MPs, the inhibition by ATU at 46 h was substantially higher than by OCT despite the full inhibition of ammonia oxidation by both inhibitors. This was particularly the case for almost all thioether and phenylurea compounds tested, suggesting that in nitrifying activated sludge communities, ATU does not exclusively act as an inhibitor of bacterial ammonia oxidation. Rather, ATU also inhibited enzymes contributing to MP biotransformation but not to bulk ammonia oxidation. Thus, inhibition studies with ATU tend to overestimate the contribution of ammonia-oxidizing bacteria to MP biotransformation in nitrifying activated sludge communities. Biolog tests revealed only minor effects of ATU on the heterotrophic respiration of common organic substrates by the sludge community, suggesting that ATU did not affect enzymes that were essential in energy conservation and central metabolism of heterotrophs. By comparing ATU

  1. Ammonia Oxidation Plant at Plum Brook Ordnance Works

    NASA Image and Video Library

    1943-06-21

    An ammonia oxidation plant at the Plum Brook Ordnance Works near Sandusky, Ohio, which later became the National Aeronautics and Space Administration’s (NASA) Plum Brook Station. During World War II the ordnance works produced trinitroluene (TNT), dinitrotoluene (DNT), and pentolite which were crated and shipped to an arsenal in Ravenna, Ohio. There, the explosives were packed into shells and sent to Allied forces overseas. Plum Brook was the third largest producer of TNT during World War II. Toluene, sulfuric acid, and nitric acid were used to manufacture the TNT. Nitric Acid is made by oxidizing ammonia, adding water, and concentrating it. The facility in this photograph was used for this oxidation. The structure included air compressors, filters, aftercoolers, power recovery systems, air receivers, heaters, ammonia gasifiers, gas mixers, cooler condensers, absorption columns, and bleaching columns. The Plum Brook Ordnance Works was shut down immediately after the war and remained vacant for the next ten years. NASA’s predecessor, the National Advisory Committee for Aeronautics (NACA), acquired the 500 acres of the site in 1955 to build a nuclear test reactor. By 1963, the agency had acquired the entire 9000 acres from the Army. Almost all of the military facilities were removed in the early 1960s. Plum Brook Station contained over 30 test facilities at its peak in the late 1960s. Today there are four major facilities in operation.

  2. Integrated structural biology and molecular ecology of N-cycling enzymes from ammonia-oxidizing archaea

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tolar, Bradley B.; Herrmann, Jonathan; Bargar, John R.

    In this paper, knowledge of the molecular ecology and environmental determinants of ammonia-oxidizing organisms is critical to understanding and predicting the global nitrogen (N) and carbon cycles, but an incomplete biochemical picture hinders in vitro studies of N-cycling enzymes. Although an integrative structural and dynamic characterization at the atomic scale would advance our understanding of function tremendously, structural knowlede of key N-cycling enzymes from ecologically-relevant ammonia oxidizers is unfortunately extremely limited. Here, we discuss the challenges and opportunities for examining the ecology of ammonia-oxidizing organisms, particularly uncultivated Thaumarchaeota, though (meta)genome-driven structural biology of the enzymes ammonia monooxygenase (AMO) andmore » nitrite reductase (NirK).« less

  3. Integrated structural biology and molecular ecology of N-cycling enzymes from ammonia-oxidizing archaea

    DOE PAGES

    Tolar, Bradley B.; Herrmann, Jonathan; Bargar, John R.; ...

    2017-07-05

    In this paper, knowledge of the molecular ecology and environmental determinants of ammonia-oxidizing organisms is critical to understanding and predicting the global nitrogen (N) and carbon cycles, but an incomplete biochemical picture hinders in vitro studies of N-cycling enzymes. Although an integrative structural and dynamic characterization at the atomic scale would advance our understanding of function tremendously, structural knowlede of key N-cycling enzymes from ecologically-relevant ammonia oxidizers is unfortunately extremely limited. Here, we discuss the challenges and opportunities for examining the ecology of ammonia-oxidizing organisms, particularly uncultivated Thaumarchaeota, though (meta)genome-driven structural biology of the enzymes ammonia monooxygenase (AMO) andmore » nitrite reductase (NirK).« less

  4. Integrated structural biology and molecular ecology of N-cycling enzymes from ammonia-oxidizing archaea.

    PubMed

    Tolar, Bradley B; Herrmann, Jonathan; Bargar, John R; van den Bedem, Henry; Wakatsuki, Soichi; Francis, Christopher A

    2017-10-01

    Knowledge of the molecular ecology and environmental determinants of ammonia-oxidizing organisms is critical to understanding and predicting the global nitrogen (N) and carbon cycles, but an incomplete biochemical picture hinders in vitro studies of N-cycling enzymes. Although an integrative structural and dynamic characterization at the atomic scale would advance our understanding of function tremendously, structural knowledge of key N-cycling enzymes from ecologically relevant ammonia oxidizers is unfortunately extremely limited. Here, we discuss the challenges and opportunities for examining the ecology of ammonia-oxidizing organisms, particularly uncultivated Thaumarchaeota, through (meta)genome-driven structural biology of the enzymes ammonia monooxygenase (AMO) and nitrite reductase (NirK). © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

  5. Emergent macrophytes modify the abundance and community composition of ammonia oxidizers in their rhizosphere sediments.

    PubMed

    Zhao, Dayong; He, Xiaowei; Huang, Rui; Yan, Wenming; Yu, Zhongbo

    2017-07-01

    Ammonia oxidation is a crucial process in global nitrogen cycling, which is catalyzed by the ammonia oxidizers. Emergent plants play important roles in the freshwater ecosystem. Therefore, it is meaningful to investigate the effects of emergent macrophytes on the abundance and community composition of ammonia oxidizers. In the present study, two commonly found emergent macrophytes (Zizania caduciflora and Phragmitas communis) were obtained from freshwater lakes and the abundance and community composition of the ammonia-oxidizing prokaryotes in the rhizosphere sediments of these emergent macrophytes were investigated. The abundance of the bacterial amoA gene was higher in the rhizosphere sediments of the emergent macrophytes than those of bulk sediments. Significant positive correlation was found between the potential nitrification rates (PNRs) and the abundance of bacterial amoA gene, suggesting that ammonia-oxidizing bacteria (AOB) might play an important role in the nitrification process of the rhizosphere sediments of emergent macrophytes. The Nitrosotalea cluster is the dominant ammonia-oxidizing archaea (AOA) group in all the sediment samples. Analysis of AOB group showed that the N. europaeal cluster dominated the rhizosphere sediments of Z. caduciflora and the bulk sediments, whereas the Nitrosospira cluster was the dominant AOB group in the rhizosphere sediments of P. communis. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Visible-Light-Promoted Metal-Free Aerobic Oxidation of Primary Amines to Acids and Lactones.

    PubMed

    Cheng, Xiaokai; Yang, Bo; Hu, Xingen; Xu, Qing; Lu, Zhan

    2016-12-05

    A unique metal-free aerobic oxidation of primary amines via visible light photocatalytic double carbon-carbon bonds cleavage and multi carbon-hydrogen bonds oxidation was observed. Aerobic oxidation of primary amines could be controlled to afford acids by using dioxane with 18 W CFL, and lactones by using DMF with 8 W green LEDs, respectively. A plausible mechanism was proposed based on control experiments. This observation showed direct evidences for the fragmentation in the aerobic oxidation of aliphatic primary amines. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. [Diversity and community structure of soil ammonia-oxidizing bacteria in Hulunbeier Grassland, Inner Mongolia].

    PubMed

    Wendu, Ri-le; Li, Gang; Yang, Dian-lin; Zhang, Jing-ni; Yi, Jin

    2011-04-01

    By the methods of polymerase chain reaction-denaturing gradient gel electrophoresis and sequence analysis, a comparative study was conducted on the diversity and community structure of soil ammonia-oxidizing bacteria in the Filifolium sibiricum steppe, Stipa baicalensis steppe, Leymus chinensis steppe, Stipa grandis steppe, and Stipa kryrowi steppe in Hulunbeier Grassland, Inner Mongolia. A significant difference was observed in the community structure of soil ammonia-oxidizing bacteria among the five steppes, with the similarity lower than 50%. The diversity of soil ammonia-oxidizing bacteria was the highest in F. sibiricum steppe, followed by in S. baicalensis steppe, L. chinensis steppe, S. kryrowi steppe, and S. grandis steppe. In the five steppes, Nitrosospira cluster 3 was the dominant group, and the Nitrosospira cluster 1, 2, and 4 as well as Nitrosomonas were also found. The community structure of soil ammonia oxidizing bacteria in F. sibiricum steppe was most complex, while that in L. chinensis steppe and S. grandis steppe was relatively simple. Correlation analysis indicated that there existed significant positive correlations between the diversity of soil ammonia-oxidizing bacteria and the soil moisture, total nitrogen, total organic carbon, and C/N ratio (P<0.05).

  8. Aerobic sulfur-oxidizing bacteria: Environmental selection and diversification

    NASA Technical Reports Server (NTRS)

    Caldwell, D.

    1985-01-01

    Sulfur-oxidizing bacteria oxidize reduced inorganic compounds to sulfuric acid. Lithotrophic sulfur oxidizer use the energy obtained from oxidation for microbial growth. Heterotrophic sulfur oxidizers obtain energy from the oxidation of organic compounds. In sulfur-oxidizing mixotrophs energy are derived either from the oxidation of inorganic or organic compounds. Sulfur-oxidizing bacteria are usually located within the sulfide/oxygen interfaces of springs, sediments, soil microenvironments, and the hypolimnion. Colonization of the interface is necessary since sulfide auto-oxidizes and because both oxygen and sulfide are needed for growth. The environmental stresses associated with the colonization of these interfaces resulted in the evolution of morphologically diverse and unique aerobic sulfur oxidizers.

  9. Effects of Agronomic Treatments on Structure and Function of Ammonia-Oxidizing Communities

    PubMed Central

    Phillips, Carol J.; Harris, Dave; Dollhopf, Sherry L.; Gross, Katherine L.; Prosser, James I.; Paul, Eldor A.

    2000-01-01

    The aim of this study was to determine the effects of different agricultural treatments and plant communities on the diversity of ammonia oxidizer populations in soil. Denaturing gradient gel electrophoresis (DGGE), coupled with specific oligonucleotide probing, was used to analyze 16S rRNA genes of ammonia oxidizers belonging to the β subgroup of the division Proteobacteria by use of DNA extracted from cultivated, successional, and native deciduous forest soils. Community profiles of the different soil types were compared with nitrification rates and most-probable-number (MPN) counts. Despite significant variation in measured nitrification rates among communities, there were no differences in the DGGE banding profiles of DNAs extracted from these soils. DGGE profiles of DNA extracted from samples of MPN incubations, cultivated at a range of ammonia concentrations, showed the presence of bands not amplified from directly extracted DNA. Nitrosomonas-like bands were seen in the MPN DNA but were not detected in the DNA extracted directly from soils. These bands were detected in some samples taken from MPN incubations carried out with medium containing 1,000 μg of NH4+-N ml−1, to the exclusion of bands detected in the native DNA. Cell concentrations of ammonia oxidizers determined by MPN counts were between 10- and 100-fold lower than those determined by competitive PCR (cPCR). Although no differences were seen in ammonia oxidizer MPN counts from the different soil treatments, cPCR revealed higher numbers in fertilized soils. The use of a combination of traditional and molecular methods to investigate the activities and compositions of ammonia oxidizers in soil demonstrates differences in fine-scale compositions among treatments that may be associated with changes in population size and function. PMID:11097922

  10. Activity, abundance and structure of ammonia-oxidizing microorganisms in plateau soils.

    PubMed

    Dai, Yu; Wu, Zhen; Zhou, Qiheng; Zhao, Qun; Li, Ningning; Xie, Shuguang; Liu, Yong

    2015-10-01

    Both ammonia-oxidizing archaea (AOA) and bacteria (AOB) can be involved in biotransformation of ammonia to nitrite in soil ecosystems. However, the distribution of AOA and AOB in plateau soils and influential factors remain largely unclear. In the present study, the activity, abundance and structure of ammonia oxidizers in different soils on the Yunnan Plateau were assessed using potential nitrification rates (PNRs), quantitative PCR assay and clone library analysis, respectively. Wide variation was found in both AOA and AOB communities in plateau soils. PNRs showed a significant positive correlation with AOB abundance. Both were determined by the ratio of organic carbon to nitrogen (C/N) and total phosphorous (TP). AOB could play a more important role in ammonia oxidation. AOB community diversity was likely affected by soil total nitrogen (TN) and total organic carbon (TOC) and was usually higher than AOA community diversity. Moreover, Nitrososphaera- and Nitrosospira-like organisms, respectively, were the dominant AOA and AOB in plateau soils. AOA community structure was likely shaped by TP and C/N, while AOB community structure was determined by pH. Copyright © 2015 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

  11. The catalytic removal of ammonia and nitrogen oxides from spacecabin atmospheres

    NASA Technical Reports Server (NTRS)

    Gully, A. J.; Graham, R. R.; Halligan, J. E.; Bentsen, P. C.

    1973-01-01

    Investigations were made on methods for the removal of ammonia and to a lesser extent nitrogen oxides in low concentrations from air. The catalytic oxidation of ammonia was studied over a temperature range of 250 F to 600 F and a concentration range 20 ppm to 500 ppm. Of the catalysts studied, 0.5 percent ruthenium supported on alumina was found to be superior. This material is active at temperatures as low as 250 F and was found to produce much less nitrous oxide than the other two active catalysts, platinum on alumina and Hopcalite. A quantitative design model was developed which will permit the performance of an oxidizer to be calculated. The ruthenium was found to be relatively insensitive to low concentrations of water and to oxygen concentration between 21 percent and 100 percent. Hydrogen sulfide was found to be a poison when injected in relatively large quantities. The adsorption of ammonia by copper sulfate treated silica gel was investigated at temperatures of 72 F and 100 F. A quantitative model was developed for predicting adsorption bed behavior.

  12. Ruthenium-Catalyzed Aerobic Oxidation of Amines.

    PubMed

    Ray, Ritwika; Hazari, Arijit Singha; Lahiri, Goutam Kumar; Maiti, Debabrata

    2018-01-18

    Amine oxidation is one of the fundamental reactions in organic synthesis as it leads to a variety of value-added products such as oximes, nitriles, imines, and amides among many others. These products comprise the key N-containing building blocks in the modern chemical industry, and such transformations, when achieved in the presence of molecular oxygen without using stoichiometric oxidants, are much preferred as they circumvent the production of unwanted wastes. In parallel, the versatility of ruthenium catalysts in various oxidative transformations is well-documented. Herein, this review focuses on aerobic oxidation of amines specifically by using ruthenium catalysts and highlights the major achievements in this direction and challenges that still need to be addressed. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Multiple factors affect diversity and abundance of ammonia-oxidizing microorganisms in iron mine soil.

    PubMed

    Xing, Yi; Si, Yan-Xiao; Hong, Chen; Li, Yang

    2015-07-01

    Ammonia oxidation by microorganisms is a critical process in the nitrogen cycle. In this study, four soil samples collected from a desert zone in an iron-exploration area and others from farmland and planted forest soil in an iron mine surrounding area. We analyzed the abundance and diversity of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in iron-mining area near the Miyun reservoir using ammonia monooxygenase. A subunit gene (amoA) as molecular biomarker. Quantitative polymerase chain reaction was applied to explore the relationships between the abundance of AOA and AOB and soil physicochemical parameters. The results showed that AOA were more abundant than AOB and may play a more dominant role in the ammonia-oxidizing process in the whole region. PCR-denaturing gradient gel electrophoresis was used to analyze the structural changes of AOA and AOB. The results showed that AOB were much more diverse than AOA. Nitrosospira cluster three constitute the majority of AOB, and AOA were dominated by group 1.1b in the soil. Redundancy analysis was performed to explore the physicochemical parameters potentially important to AOA and AOB. Soil characteristics (i.e. water, ammonia, organic carbon, total nitrogen, available phosphorus, and soil type) were proposed to potentially contribute to the distributions of AOB, whereas Cd was also closely correlated to the distributions of AOB. The community of AOA correlated with ammonium and water contents. These results highlight the importance of multiple drivers in microbial niche formation as well as their affect on ammonia oxidizer composition, both which have significant consequences for ecosystem nitrogen functioning.

  14. Low-ammonia niche of ammonia-oxidizing archaea in rotating biological contactors of a municipal wastewater treatment plant

    PubMed Central

    Sauder, Laura A; Peterse, Francien; Schouten, Stefan; Neufeld, Josh D

    2012-01-01

    The first step of nitrification is catalysed by both ammonia-oxidizing bacteria (AOB) and archaea (AOA), but physicochemical controls on the relative abundance and function of these two groups are not yet fully understood, especially in freshwater environments. This study investigated ammonia-oxidizing populations in nitrifying rotating biological contactors (RBCs) from a municipal wastewater treatment plant. Individual RBC stages are arranged in series, with nitrification at each stage creating an ammonia gradient along the flowpath. This RBC system provides a valuable experimental system for testing the hypothesis that ammonia concentration determines the relative abundance of AOA and AOB. The results demonstrate that AOA increased as ammonium decreased across the RBC flowpath, as indicated by qPCR for thaumarchaeal amoA and 16S rRNA genes, and core lipid (CL) and intact polar lipid (IPL) crenarchaeol abundances. Overall, there was a negative logarithmic relationship (R2 = 0.51) between ammonium concentration and the relative abundance of AOA amoA genes. A single AOA population was detected in the RBC biofilms; this phylotype shared low amoA and 16S rRNA gene homology with existing AOA cultures and enrichments. These results provide evidence that ammonia availability influences the relative abundances of AOA and AOB, and that AOA are abundant in some municipal wastewater treatment systems. PMID:22639927

  15. [Restoration of microbial ammonia oxidizers in air-dried forest soils upon wetting].

    PubMed

    Zhou, Xue; Huang, Rong; Song, Ge; Pan, Xianzhang; Jia, Zhongjun

    2014-11-04

    This study was aimed to investigate the abundance and community shift of ammonia-oxidizing archaea (AOA) and bacteria (AOB) in air-dried forest soils in response to water addition, to explore the applicability of air-dried soil for microbial ecology study, and to elucidate whether AOA within the marine group 1. 1a dominate ammonia oxidizers communities in the acidic forest soils in China. Soil samples were collected from 10 forest sites of the China Ecosystem Research Network (CERN) and kept under air-drying conditions in 2010. In 2013 the air-dried soil samples were adjusted to 60% of soil maximum water holding capacity for a 28-day incubation at 28 degrees C in darkness. DGGE fingerprinting, clone library construction, pyrosequencing and quantitative PCR of amoA genes were performed to assess community change of ammonia oxidizers in air-dried and re-wetted soils. After incubation for 28 days, the abundance of bacteria and archaea increased significantly, up to 3,230 and 568 times, respectively. AOA increased significantly in 8 samples, and AOB increased significantly in 5 of 10 samples. However, pyrosequencing of amoA genes reveals insignificant changes in composition of AOA and AOB communities. Phylogenetic analysis of amoA genes indicates that archaeal ammonia oxidizers were predominated by AOA within the soil group 1. 1b lineage, while the Nitrosospira-like AOB dominate bacteria ammonia oxidizer communities. There was a significantly positive correlation between AOA/AOB ratio and total nitrogen (r2 = 0.54, P < 0.05), implying that soil ammonia oxidation might be dominated by AOA in association with ammonium released from soil mineralization. Phylogenetic analysis suggest that AOA members within the soil group 1. 1b lineage were not restricted to non-acidic soils as previously thought. The abundance rather than composition of AOA and AOB changed in response to water addition. This indicates that air-dried soil could be of help for microbial biogeography study.

  16. Investigation of Pristine Graphite Oxide as Room-Temperature Chemiresistive Ammonia Gas Sensing Material.

    PubMed

    Bannov, Alexander G; Prášek, Jan; Jašek, Ondřej; Zajíčková, Lenka

    2017-02-09

    Graphite oxide has been investigated as a possible room-temperature chemiresistive sensor of ammonia in a gas phase. Graphite oxide was synthesized from high purity graphite using the modified Hummers method. The graphite oxide sample was investigated using scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, thermogravimetry and differential scanning calorimetry. Sensing properties were tested in a wide range of ammonia concentrations in air (10-1000 ppm) and under different relative humidity levels (3%-65%). It was concluded that the graphite oxide-based sensor possessed a good response to NH₃ in dry synthetic air (ΔR/R₀ ranged from 2.5% to 7.4% for concentrations of 100-500 ppm and 3% relative humidity) with negligible cross-sensitivity towards H₂ and CH₄. It was determined that the sensor recovery rate was improved with ammonia concentration growth. Increasing the ambient relative humidity led to an increase of the sensor response. The highest response of 22.2% for 100 ppm of ammonia was achieved at a 65% relative humidity level.

  17. Dynamic Response of Ammonia-Oxidizers to Four Fertilization Regimes across a Wheat-Rice Rotation System

    PubMed Central

    Wang, Jichen; Ni, Lei; Song, Yang; Rhodes, Geoff; Li, Jing; Huang, Qiwei; Shen, Qirong

    2017-01-01

    Ammonia oxidation by microorganisms is a rate-limiting step of the nitrification process and determines the efficiency of fertilizer utilized by crops. Little is known about the dynamic response of ammonia-oxidizers to different fertilization regimes in a wheat-rice rotation system. Here, we examined ammonia-oxidizing bacteria (AOB) and archaea (AOA) communities across eight representative stages of wheat and rice growth and under four fertilization regimes: no nitrogen fertilization (NNF), chemical fertilization (CF), organic-inorganic mixed fertilizer (OIMF) and organic fertilization (OF). The abundance and composition of ammonia oxidizers were analyzed using quantitative PCR (qPCR) and terminal restriction fragment length polymorphism (T-RFLP) of their amoA genes. Results showed that fertilization but not plant growth stages was the best predictor of soil AOB community abundance and composition. Soils fertilized with more urea-N had higher AOB abundance, while organic-N input showed little effect on AOB abundance. 109 bp T-RF (Nitrosospira Cluster 3b) and 280 bp T-RF (Nitrosospira Cluster 3c) dominated the AOB communities with opposing responses to fertilization regimes. Although the abundance and composition of the AOA community was significantly impacted by fertilization and plant growth stage, it differed from the AOB community in that there was no particular trend. In addition, across the whole wheat-rice rotation stages, results of multiple stepwise linear regression revealed that AOB played a more important role in ammonia oxidizing process than AOA. This study provided insight into the dynamic effects of fertilization strategies on the abundance and composition of ammonia-oxidizers communities, and also offered insights into the potential of managing nitrogen for sustainable agricultural productivity with respect to soil ammonia-oxidizers. PMID:28446904

  18. Growth of Nitrosococcus-Related Ammonia Oxidizing Bacteria Coincides with Extremely Low pH Values in Wastewater with High Ammonia Content

    PubMed Central

    2017-01-01

    Ammonia oxidation decreases the pH in wastewaters where alkalinity is limited relative to total ammonia. The activity of ammonia oxidizing bacteria (AOB), however, typically decreases with pH and often ceases completely in slightly acidic wastewaters. Nevertheless, nitrification at low pH has been reported in reactors treating human urine, but it has been unclear which organisms are involved. In this study, we followed the population dynamics of ammonia oxidizing organisms and reactor performance in synthetic fully hydrolyzed urine as the pH decreased over time in response to a decrease in the loading rate. Populations of the β-proteobacterial Nitrosomonas europaea lineage were abundant at the initial pH close to 6, but the growth of a possibly novel Nitrosococcus-related AOB genus decreased the pH to the new level of 2.2, challenging the perception that nitrification is inhibited entirely at low pH values, or governed exclusively by β-proteobacterial AOB or archaea. With the pH shift, nitrite oxidizing bacteria were not further detected, but nitrous acid (HNO2) was still removed through chemical decomposition to nitric oxide (NO) and nitrate. The growth of acid-tolerant γ-proteobacterial AOB should be prevented, by keeping the pH above 5.4, which is a typical pH limit for the N. europaea lineage. Otherwise, the microbial community responsible for high-rate nitrification can be lost, and strong emissions of hazardous volatile nitrogen compounds such as NO are likely. PMID:28509546

  19. Short-term effect of ammonia concentration and salinity on activity of ammonia oxidizing bacteria.

    PubMed

    Claros, J; Jiménez, E; Borrás, L; Aguado, D; Seco, A; Ferrer, J; Serralta, J

    2010-01-01

    A continuously aerated SHARON (single reactor high activity ammonia removal over nitrite) system has been operated to achieve partial nitritation. Two sets of batch experiments were carried out to study the effect of ammonia concentration and salinity on the activity of ammonia-oxidizing bacteria (AOB). Activity of AOB raised as free ammonia concentration was increased reaching its maximum value at 4.5 mg NH3-N l(-1). The half saturation constant for free ammonia was determined (K(NH3)=0.32 mg NH3-N l(-1)). Activity decreased at TAN (total ammonium-nitrogen) concentration over 2,000 mg NH4-N l(-1). No free ammonia inhibition was detected. The effect of salinity was studied by adding different concentrations of different salts to the biomass. No significant differences were observed between the experiments carried out with a salt containing or not containing NH4. These results support that AOB are inhibited by salinity, not by free ammonia. A mathematical expression to represent this inhibition is proposed. To compare substrate affinity and salinity inhibitory effect on different AOB populations, similar experiments were carried out with biomass from a biological nutrient removal pilot plant. The AOB activity reached its maximum value at 0.008 mg NH3-N l(-1) and decreased at TAN concentration over 400 mg NH4-N l(-1). These differences can be explained by the different AOB predominating species: Nitrosomonas europaea and N. eutropha in the SHARON biomass and Nitrosomonas oligotropha in the pilot plant.

  20. Contributions of ammonia-oxidizing archaea and bacteria to nitrification in Oregon forest soils

    Treesearch

    Xinda Lu; Peter J. Bottomley; David D. Myrold

    2015-01-01

    Ammonia oxidation, the first step of nitrification, is mediated by both ammonia-oxidizing archaea (AOA) and bacteria (AOB); however, the relative contributions of AOA and AOB to soil nitrification are not well understood. In this study we used 1-octyne to discriminate between AOA-and AOB-supported nitrifi-cation determined both in soil-water slurries and in unsaturated...

  1. Adaptation of ammonia-oxidizing microorganisms to environment shift of paddy field soil.

    PubMed

    Ke, Xiubin; Lu, Yahai

    2012-04-01

    Adaptation of microorganisms to the environment is a central theme in microbial ecology. The objective of this study was to investigate the response of ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) to a soil medium shift. We employed two rice field soils collected from Beijing and Hangzhou, China. These soils contained distinct AOB communities dominated by Nitrosomonas in Beijing rice soil and Nitrosospira in Hangzhou rice soil. Three mixtures were generated by mixing equal quantities of Beijing soil and Hangzhou soil (BH), Beijing soil with sterilized Hangzhou soil (BSH), and Hangzhou soil with sterilized Beijing soil (HSB). Pure and mixed soils were permanently flooded, and the surface-layer soil where ammonia oxidation occurred was collected to determine the response of AOB and AOA to the soil medium shift. AOB populations increased during the incubation, and the rates were initially faster in Beijing soil than in Hangzhou soil. Nitrosospira (cluster 3a) and Nitrosomonas (communis cluster) increased with time in correspondence with ammonia oxidation in the Hangzhou and Beijing soils, respectively. The 'BH' mixture exhibited a shift from Nitrosomonas at day 0 to Nitrosospira at days 21 and 60 when ammonia oxidation became most active. In 'HSB' and 'BSH' mixtures, Nitrosospira showed greater stimulation than Nitrosomonas, both with and without N amendment. These results suggest that Nitrosospira spp. were better adapted to soil environment shifts than Nitrosomonas. Analysis of the AOA community revealed that the composition of AOA community was not responsive to the soil environment shifts or to nitrogen amendment. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  2. Direct electrochemical oxidation of ammonia on graphite as a treatment option for stored source-separated urine.

    PubMed

    Zöllig, Hanspeter; Fritzsche, Cristina; Morgenroth, Eberhard; Udert, Kai M

    2015-02-01

    Electrolysis can be a viable technology for ammonia removal from source-separated urine. Compared to biological nitrogen removal, electrolysis is more robust and is highly amenable to automation, which makes it especially attractive for on-site reactors. In electrolytic wastewater treatment, ammonia is usually removed by indirect oxidation through active chlorine which is produced in-situ at elevated anode potentials. However, the evolution of chlorine can lead to the formation of chlorate, perchlorate, chlorinated organic by-products and chloramines that are toxic. This study focuses on using direct ammonia oxidation on graphite at low anode potentials in order to overcome the formation of toxic by-products. With the aid of cyclic voltammetry, we demonstrated that graphite is active for direct ammonia oxidation without concomitant chlorine formation if the anode potential is between 1.1 and 1.6 V vs. SHE (standard hydrogen electrode). A comparison of potentiostatic bulk electrolysis experiments in synthetic stored urine with and without chloride confirmed that ammonia was removed exclusively by continuous direct oxidation. Direct oxidation required high pH values (pH > 9) because free ammonia was the actual reactant. In real stored urine (pH = 9.0), an ammonia removal rate of 2.9 ± 0.3 gN·m(-2)·d(-1) was achieved and the specific energy demand was 42 Wh·gN(-1) at an anode potential of 1.31 V vs. SHE. The measurements of chlorate and perchlorate as well as selected chlorinated organic by-products confirmed that no chlorinated by-products were formed in real urine. Electrode corrosion through graphite exfoliation was prevented and the surface was not poisoned by intermediate oxidation products. We conclude that direct ammonia oxidation on graphite electrodes is a treatment option for source-separated urine with three major advantages: The formation of chlorinated by-products is prevented, less energy is consumed than in indirect ammonia oxidation and

  3. Nitrification resilience and community dynamics of ammonia-oxidizing bacteria with respect to ammonia loading shock in a nitrification reactor treating steel wastewater.

    PubMed

    Cho, Kyungjin; Shin, Seung Gu; Lee, Joonyeob; Koo, Taewoan; Kim, Woong; Hwang, Seokhwan

    2016-08-01

    The aim of this study was to investigate the nitrification resilience pattern and examine the key ammonia-oxidizing bacteria (AOB) with respect to ammonia loading shocks (ALSs) in a nitrification bioreactor treating steel wastewater. The perturbation experiments were conducted in a 4-L bioreactor operated in continuous mode with a hydraulic retention time of 10 d. Three sequential ALSs were given to the bioreactor (120, 180 and 180 mg total ammonia nitrogen (TAN)/L. When the first shock was given, the nitrification process completely recovered after 14 d of further operation. However, the resilience duration was significantly reduced to ∼1 d after the second and third ALSs. In the bioreactor, Nitrosomonas aestuarii dominated the other AOB species, Nitrosomonas europaea and N. nitrosa, throughout the process. In addition, the population of N. aestuarii increased with ammonia utilization following each ALS; i.e., this species responded to acute ammonia overloadings by contributing to ammonia oxidation. This finding suggests that N. aestuarii could be exploited to achieve stable nitrification in industrial wastewaters that contain high concentrations of ammonia. Copyright © 2016 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  4. Effect of aerobic exercise intervention on DDT degradation and oxidative stress in rats.

    PubMed

    Li, Kefeng; Zhu, Xiaohua; Wang, Yuzhan; Zheng, Shuqian; Dong, Guijun

    2017-03-01

    Dichlorodiphenyltrichloroethane (DDT) reportedly causes extensively acute or chronic effects to human health. Exercise can generate positive stress. We evaluated the effect of aerobic exercise on DDT degradation and oxidative stress. Male Wistar rats were randomly assigned into control (C), DDT without exercise training (D), and DDT plus exercise training (DE) groups. The rats were treated as follows: DDT exposure to D and DE groups at the first 2 weeks; aerobic exercise treatment only to the DE group from the 1st day until the rats are killed. DDT levels in excrements, muscle, liver, serum, and hearts were analyzed. Superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), and malondialdehyde (MDA) levels were determined. Aerobic exercise accelerated the degradation of DDT primarily to DDE due to better oxygen availability and aerobic condition and promoted the degradation of DDT. Cumulative oxidative damage of DDT and exercise led to significant decrease of SOD level. Exercise resulted in consistent increase in SOD activity. Aerobic exercise enhanced activities of CAT and GSH-Px and promoted MDA scavenging. Results suggested that exercise can accelerate adaptive responses to oxidative stress and activate antioxidant enzymes activities. Exercise can also facilitate the reduction of DDT-induced oxidative damage and promoted DDT degradation. This study strongly implicated the positive effect of exercise training on DDT-induced liver oxidative stress.

  5. The Distribution of Ammonia-Oxidizing Betaproteobacteria in Stands of Black Mangroves (Avicennia germinans)

    PubMed Central

    Laanbroek, Hendrikus J.; Keijzer, Rosalinde M.; Verhoeven, Jos T. A.; Whigham, Dennis F.

    2012-01-01

    The distribution of species of aerobic chemolitho-autotrophic microorganisms such as ammonia-oxidizing bacteria are governed by pH, salinity, and temperature as well as the availability of oxygen, ammonium, carbon dioxide, and other inorganic elements required for growth. Impounded mangrove forests in the Indian River Lagoon, a coastal estuary on the east coast of Florida, are dominated by mangroves, especially stands of Black mangrove (Avicennia germinans) that differ in the size and density of individual plants. In March 2009, the management of one impoundment was changed to a regime of pumping estuarine water into the impoundment at critical times of the year to eliminate breeding sites for noxious insects. We collected soil samples in three different Black mangrove habitats before and after the change in management to determine the impacts of the altered hydrologic regimes on the distribution of 16s rRNA genes belonging to ammonia-oxidizing betaproteobacteria (β-AOB). We also sampled soils in an adjacent impoundment in which there had not been any hydrologic alteration. At the level of 97% mutual similarity in the 16s rRNA gene, 13 different operational taxonomic units were identified; the majority related to the lineages of Nitrosomonas marina (45% of the total clones), Nitrosomonas sp. Nm143 (23%), and Nitrosospira cluster 1 (19%). Long-term summer flooding of the impoundment in 2009, after initiation of the pumping regime, reduced the percentage of N. marina by half between 2008 and 2010 in favor of the two other major lineages and the potential ammonia-oxidizing activity decreased by an average of 73%. Higher interstitial salinities, probably due to a prolonged winter drought, had a significant effect on the composition of the β-AOB in March 2009 compared to March 2008: Nitrosomonas sp. Nm143 was replaced by Nitrosospira cluster 1 as the second most important lineage. There were small, but significant differences in the bacterial communities between the

  6. Aerobic Methane Oxidation in Alaskan Lakes Along a Latitudinal Transect

    NASA Astrophysics Data System (ADS)

    Martinez-Cruz, K. C.; Sepulveda-Jauregui, A.; Walter Anthony, K. M.; Anthony, P.; Thalasso, F.

    2013-12-01

    Karla Martinez-Cruz* **, Armando Sepulveda-Jauregui*, Katey M. Walter Anthony*, Peter Anthony*, and Frederic Thalasso**. * Water and Environmental Research Center, Institute of Northern Engineering, University of Alaska Fairbanks, Fairbanks, Alaska. ** Biotechnology and Bioengineering Department, Cinvestav, Mexico city, D. F., Mexico. Methane (CH4) is the third most important greenhouse gas in the atmosphere, after carbon dioxide and water vapor. Boreal lakes play an important role in the current global warming by contributing as much as 6% of global atmospheric CH4 sources annually. On the other hand, aerobic methane oxidation (methanotrophy) in lake water is a fundamental process in global methane cycling that reduces the amount of CH4 emissions to the atmosphere. Several environmental factors affect aerobic methane oxidation in the water column both directly and indirectly, including concentration of CH4 and O2, temperature and carbon budgets of lakes. We analyzed the potential of aerobic methane oxidation (PMO) rates in incubations of water collected from 30 Alaskan lakes along a north-south transect during winter and summer 2011. Our findings showed an effect of CH4 and O2 concentrations, temperature and yedoma thawing permafrost on PMO activity in the lake water. The highest PMO rates were observed in summer by lakes situated on thawing yedoma permafrost, most of them located in the interior of Alaska. We also estimated that 60-80% of all CH4 produced in Alaskan lakes could be taken up by methanotrophs in the lake water column, showing the significant influence of aerobic methane oxidation of boreal lakes to the global CH4 budget.

  7. Nitrogen isotope fractionation during archaeal ammonia oxidation: Coupled estimates from isotopic measurements of ammonium and nitrite

    NASA Astrophysics Data System (ADS)

    Mooshammer, Maria; Stieglmeier, Michaela; Bayer, Barbara; Jochum, Lara; Melcher, Michael; Wanek, Wolfgang

    2014-05-01

    Ammonia-oxidizing archaea (AOA) are ubiquitous in marine and terrestrial environments and knowledge about the nitrogen (N) isotope effect associated with their ammonia oxidation activity will allow a better understanding of natural abundance isotope ratios, and therefore N transformation processes, in the environment. Here we examine the kinetic isotope effect for ammonia oxidation in a pure soil AOA culture (Ca. Nitrososphaera viennensis) and a marine AOA enrichment culture. We estimated the isotope effect from both isotopic signatures of ammonium and nitrite over the course of ammonia oxidation. Estimates of the isotope effect based on the change in the isotopic signature of ammonium give valuable insight, because these estimates are not subject to the same concerns (e.g., accumulation of an intermediate) as estimates based on isotopic measurements of nitrite. Our results show that both the pure soil AOA culture and a marine AOA enrichment culture have similar but substantial isotope effect during ammonia consumption (31-34 per mill; based on ammonium) and nitrite production (43-45 per mill; based on nitrite). The 15N fractionation factors of both cultures tested fell in the upper range of the reported isotope effects for archaeal and bacterial ammonia oxidation (10-41 per mill) or were even higher than those. The isotope fractionation for nitrite production was significantly larger than for ammonium consumption, indicating that (1) some intermediate (e.g., hydroxylamine) of ammonia oxidation accumulates, allowing for a second 15N fractionation step to be expressed, (2) a fraction of ammonia oxidized is lost via gaseous N forms (e.g., NO or N2O), which is 15N-enriched or (3) a fraction of ammonium is assimilated into AOA biomass, biomass becoming 15N-enriched. The significance of these mechanisms will be explored in more detail for the soil AOA culture, based on isotope modeling and isotopic measurements of biomass and N2O.

  8. Simazine biodegradation and community structures of ammonia-oxidizing microorganisms in bioaugmented soil: impact of ammonia and nitrate nitrogen sources.

    PubMed

    Wan, Rui; Yang, Yuyin; Sun, Weimin; Wang, Zhao; Xie, Shuguang

    2014-02-01

    The objective of the present study was to investigate the impact of ammonia and nitrate nitrogen sources on simazine biodegradation by Arthrobacter sp. strain SD1 and the community structures of ammonia-oxidizing archaea (AOA) and bacteria (AOB) in non-agricultural soil. Soil microcosms with different treatments were constructed for herbicide biodegradation test. The relative abundance of the strain SD1 and the structures of AOA and AOB communities were assessed using quantitative PCR (q-PCR) and terminal restriction fragment length polymorphism (TRFLP), respectively. The co-existence of two inorganic nitrogen sources (ammonia and nitrate) had certain impact on simazine dissipation by the strain SD1. Bioaugmentation could induce a shift in the community structures of both AOA and AOB, but AOA were more responsive. Nitrogen application had significant impacts on AOA and AOB communities in bioaugmented soils. Moreover, in non-bioaugmented soil, the community structure of AOA, instead of AOB, could be quickly recovered after herbicide application. This study could add some new insights towards the impacts of nitrogen sources on s-triazine bioremediation and ammonia-oxidizing microorganisms in soil ecosystem.

  9. Phylogenetically diverse denitrifying and ammonia-oxidizing bacteria in corals Alcyonium gracillimum and Tubastraea coccinea.

    PubMed

    Yang, Shan; Sun, Wei; Zhang, Fengli; Li, Zhiyong

    2013-10-01

    To date, the association of coral-bacteria and the ecological roles of bacterial symbionts in corals remain largely unknown. In particular, little is known about the community components of bacterial symbionts of corals involved in the process of denitrification and ammonia oxidation. In this study, the nitrite reductase (nirS and nirK) and ammonia monooxygenase subunit A (amoA) genes were used as functional markers. Diverse bacteria with the potential to be active as denitrifiers and ammonia-oxidizing bacteria (AOB) were found in two East China Sea corals: stony coral Alcyonium gracillimum and soft coral Tubastraea coccinea. The 16S rRNA gene library analysis demonstrated different communities of bacterial symbionts in these two corals of the same location. Nitrite reductase nirK gene was found only in T. coccinea, while both nirK and nirS genes were detected in A. gracillimum, which might be the result of the presence of different bacterial symbionts in these two corals. AOB rather than ammonia-oxidizing archaea were detected in both corals, suggesting that AOB might play an important role in the ammonia oxidation process of the corals. This study indicates that the coral bacterial symbionts with the potential for nitrite reduction and ammonia oxidation might have multiple ecological roles in the coral holobiont, which promotes our understanding of bacteria-mediated nitrogen cycling in corals. To our knowledge, this study is the first assessment of the community structure and phylogenetic diversity of denitrifying bacteria and AOB in corals based on nirK, nirS, and amoA gene library analysis.

  10. Ammonia oxidation is not required for growth of Group 1.1c soil Thaumarchaeota.

    PubMed

    Weber, Eva B; Lehtovirta-Morley, Laura E; Prosser, James I; Gubry-Rangin, Cécile

    2015-03-01

    Thaumarchaeota are among the most abundant organisms on Earth and are ubiquitous. Within this phylum, all cultivated representatives of Group 1.1a and Group 1.1b Thaumarchaeota are ammonia oxidizers, and play a key role in the nitrogen cycle. While Group 1.1c is phylogenetically closely related to the ammonia-oxidizing Thaumarchaeota and is abundant in acidic forest soils, nothing is known about its physiology or ecosystem function. The goal of this study was to perform in situ physiological characterization of Group 1.1c Thaumarchaeota by determining conditions that favour their growth in soil. Several acidic grassland, birch and pine tree forest soils were sampled and those with the highest Group 1.1c 16S rRNA gene abundance were incubated in microcosms to determine optimal growth temperature, ammonia oxidation and growth on several organic compounds. Growth of Group 1.1c Thaumarchaeota, assessed by qPCR of Group 1.1c 16S rRNA genes, occurred in soil, optimally at 30°C, but was not associated with ammonia oxidation and the functional gene amoA could not be detected. Growth was also stimulated by addition of organic nitrogen compounds (glutamate and casamino acids) but not when supplemented with organic carbon alone. This is the first evidence for non-ammonia oxidation associated growth of Thaumarchaeota in soil. © FEMS 2015.

  11. Ammonia-Oxidizing Archaea Show More Distinct Biogeographic Distribution Patterns than Ammonia-Oxidizing Bacteria across the Black Soil Zone of Northeast China.

    PubMed

    Liu, Junjie; Yu, Zhenhua; Yao, Qin; Sui, Yueyu; Shi, Yu; Chu, Haiyan; Tang, Caixian; Franks, Ashley E; Jin, Jian; Liu, Xiaobing; Wang, Guanghua

    2018-01-01

    Black soils (Mollisols) of northeast China are highly productive and agriculturally important for food production. Ammonia-oxidizing microbes play an important role in N cycling in the black soils. However, the information related to the composition and distribution of ammonia-oxidizing microbes in the black soils has not yet been addressed. In this study, we used the amoA gene to quantify the abundance and community composition of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) across the black soil zone. The amoA abundance of AOA was remarkably larger than that of AOB, with ratios of AOA/AOB in the range from 3.1 to 91.0 across all soil samples. The abundance of AOA amoA was positively correlated with total soil C content ( p < 0.001) but not with soil pH ( p > 0.05). In contrast, the abundance of AOB amoA positively correlated with soil pH ( p = 0.009) but not with total soil C. Alpha diversity of AOA did not correlate with any soil parameter, however, alpha diversity of AOB was affected by multiple soil factors, such as soil pH, total P, N, and C, available K content, and soil water content. Canonical correspondence analysis indicated that the AOA community was mainly affected by the sampling latitude, followed by soil pH, total P and C; while the AOB community was mainly determined by soil pH, as well as total P, C and N, water content, and sampling latitude, which highlighted that the AOA community was more geographically distributed in the black soil zone of northeast China than AOB community. In addition, the pairwise analyses showed that the potential nitrification rate (PNR) was not correlated with alpha diversity but weakly positively with the abundance of the AOA community ( p = 0.048), whereas PNR significantly correlated positively with the richness ( p = 0.003), diversity ( p = 0.001) and abundance ( p < 0.001) of the AOB community, which suggested that AOB community might make a greater contribution to nitrification than AOA

  12. Ammonia-Oxidizing Archaea Show More Distinct Biogeographic Distribution Patterns than Ammonia-Oxidizing Bacteria across the Black Soil Zone of Northeast China

    PubMed Central

    Liu, Junjie; Yu, Zhenhua; Yao, Qin; Sui, Yueyu; Shi, Yu; Chu, Haiyan; Tang, Caixian; Franks, Ashley E.; Jin, Jian; Liu, Xiaobing; Wang, Guanghua

    2018-01-01

    Black soils (Mollisols) of northeast China are highly productive and agriculturally important for food production. Ammonia-oxidizing microbes play an important role in N cycling in the black soils. However, the information related to the composition and distribution of ammonia-oxidizing microbes in the black soils has not yet been addressed. In this study, we used the amoA gene to quantify the abundance and community composition of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) across the black soil zone. The amoA abundance of AOA was remarkably larger than that of AOB, with ratios of AOA/AOB in the range from 3.1 to 91.0 across all soil samples. The abundance of AOA amoA was positively correlated with total soil C content (p < 0.001) but not with soil pH (p > 0.05). In contrast, the abundance of AOB amoA positively correlated with soil pH (p = 0.009) but not with total soil C. Alpha diversity of AOA did not correlate with any soil parameter, however, alpha diversity of AOB was affected by multiple soil factors, such as soil pH, total P, N, and C, available K content, and soil water content. Canonical correspondence analysis indicated that the AOA community was mainly affected by the sampling latitude, followed by soil pH, total P and C; while the AOB community was mainly determined by soil pH, as well as total P, C and N, water content, and sampling latitude, which highlighted that the AOA community was more geographically distributed in the black soil zone of northeast China than AOB community. In addition, the pairwise analyses showed that the potential nitrification rate (PNR) was not correlated with alpha diversity but weakly positively with the abundance of the AOA community (p = 0.048), whereas PNR significantly correlated positively with the richness (p = 0.003), diversity (p = 0.001) and abundance (p < 0.001) of the AOB community, which suggested that AOB community might make a greater contribution to nitrification than AOA community

  13. Effects of copper on the abundance and diversity of ammonia oxidizers during dairy cattle manure composting.

    PubMed

    Yin, Yanan; Song, Wen; Gu, Jie; Zhang, Kaiyu; Qian, Xun; Zhang, Xin; Zhang, Yajun; Li, Yang; Wang, Xiaojuan

    2016-12-01

    This study investigated the effects of adding Cu(II) at two exposure levels (50 and 500mgkg -1 , i.e., Cu50 and Cu500 treatments, respectively) on the activity of ammonia-oxidizing microorganisms during dairy cattle manure composting. The results showed that the pH, NH 4 + -N, NO 3 - -N, and potential ammonia oxidation values were inhibited significantly by the addition of Cu(II). Furthermore, the abundances of the ammonia-oxidizing archaea (AOA) amoA gene and ammonia-oxidizing bacteria (AOB) amoA gene were determined by quantitative PCR, and their compositions were evaluated by denaturing gradient gel electrophoresis (DGGE). AOA was the dominant ammonia oxidizing microorganism, of which the abundance was much higher than AOB during composting. Cu50 and Cu500 had significant inhibitory effects on the abundance of the amoA gene. The DGGE profile and statistical analysis showed that Cu(II) changed the AOA and AOB community structure and diversity, where Nitrosomonas and Crenarchaeota dominated throughout the composting process. Copyright © 2016. Published by Elsevier Ltd.

  14. Interactions between ammonia and nitrite oxidizing bacteria in co-cultures: Is there evidence for mutualism, commensalism, or competition?

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sayavedra-Soto, Luis; Arp, Daniel

    Nitrification is a two-step environmental microbial process in the nitrogen cycle in which ammonia is oxidized to nitrate. Ammonia-oxidizing bacteria and archaea oxidize ammonia to nitrite and nitrite is oxidized to nitrate by nitrite-oxidizing bacteria. These microorganisms, which likely act in concert in a microbial community, play critical roles in the movement of inorganic N in soils, sediments and waters and are essential to the balance of the nitrogen cycle. Anthropogenic activity has altered the balance of the nitrogen cycle through agriculture practices and organic waste byproducts. Through their influence on available N for plant growth, nitrifying microorganisms influence plantmore » productivity for food and fiber production and the associated carbon sequestration. N Fertilizer production, primarily as ammonia, requires large inputs of natural gas and hydrogen. In croplands fertilized with ammonia-based fertilizers, nitrifiers contribute to the mobilization of this N by producing nitrate (NO3-), wasting the energy used in the production and application of ammonia-based fertilizer. The resulting nitrate is readily leached from these soils, oxidized to gaseous N oxides (greenhouse gases), and denitrified to N2 (which is no longer available as a plant N source). Still, ammonia oxidizers are beneficial in the treatment of wastewater and they also show potential to contribute to microbial bioremediation strategies for clean up of environments contaminated with chlorinated hydrocarbons. Mitigation of the negative effects and exploitation of the beneficial effects of nitrifiers will be facilitated by a systems-level understanding of the interactions of ammonia-oxidizing bacteria and nitrite-oxidizing bacteria with the environment and with each other.« less

  15. Urease gene-containing Archaea dominate autotrophic ammonia oxidation in two acid soils.

    PubMed

    Lu, Lu; Jia, Zhongjun

    2013-06-01

    The metabolic traits of ammonia-oxidizing archaea (AOA) and bacteria (AOB) interacting with their environment determine the nitrogen cycle at the global scale. Ureolytic metabolism has long been proposed as a mechanism for AOB to cope with substrate paucity in acid soil, but it remains unclear whether urea hydrolysis could afford AOA greater ecological advantages. By combining DNA-based stable isotope probing (SIP) and high-throughput pyrosequencing, here we show that autotrophic ammonia oxidation in two acid soils was predominately driven by AOA that contain ureC genes encoding the alpha subunit of a putative archaeal urease. In urea-amended SIP microcosms of forest soil (pH 5.40) and tea orchard soil (pH 3.75), nitrification activity was stimulated significantly by urea fertilization when compared with water-amended soils in which nitrification resulted solely from the oxidation of ammonia generated through mineralization of soil organic nitrogen. The stimulated activity was paralleled by changes in abundance and composition of archaeal amoA genes. Time-course incubations indicated that archaeal amoA genes were increasingly labelled by (13) CO2 in both microcosms amended with water and urea. Pyrosequencing revealed that archaeal populations were labelled to a much greater extent in soils amended with urea than water. Furthermore, archaeal ureC genes were successfully amplified in the (13) C-DNA, and acetylene inhibition suggests that autotrophic growth of urease-containing AOA depended on energy generation through ammonia oxidation. The sequences of AOB were not detected, and active AOA were affiliated with the marine Group 1.1a-associated lineage. The results suggest that ureolytic N metabolism could afford AOA greater advantages for autotrophic ammonia oxidation in acid soil, but the mechanism of how urea activates AOA cells remains unclear. © 2012 Society for Applied Microbiology and Blackwell Publishing Ltd.

  16. Light-Dependent Aerobic Methane Oxidation Reduces Methane Emissions from Seasonally Stratified Lakes

    PubMed Central

    Oswald, Kirsten; Milucka, Jana; Brand, Andreas; Littmann, Sten; Wehrli, Bernhard; Kuypers, Marcel M. M.; Schubert, Carsten J.

    2015-01-01

    Lakes are a natural source of methane to the atmosphere and contribute significantly to total emissions compared to the oceans. Controls on methane emissions from lake surfaces, particularly biotic processes within anoxic hypolimnia, are only partially understood. Here we investigated biological methane oxidation in the water column of the seasonally stratified Lake Rotsee. A zone of methane oxidation extending from the oxic/anoxic interface into anoxic waters was identified by chemical profiling of oxygen, methane and δ13C of methane. Incubation experiments with 13C-methane yielded highest oxidation rates within the oxycline, and comparable rates were measured in anoxic waters. Despite predominantly anoxic conditions within the zone of methane oxidation, known groups of anaerobic methanotrophic archaea were conspicuously absent. Instead, aerobic gammaproteobacterial methanotrophs were identified as the active methane oxidizers. In addition, continuous oxidation and maximum rates always occurred under light conditions. These findings, along with the detection of chlorophyll a, suggest that aerobic methane oxidation is tightly coupled to light-dependent photosynthetic oxygen production both at the oxycline and in the anoxic bottom layer. It is likely that this interaction between oxygenic phototrophs and aerobic methanotrophs represents a widespread mechanism by which methane is oxidized in lake water, thus diminishing its release into the atmosphere. PMID:26193458

  17. Simazine application inhibits nitrification and changes the ammonia-oxidizing bacterial communities in a fertilized agricultural soil.

    PubMed

    Hernández, Marcela; Jia, Zhongjun; Conrad, Ralf; Seeger, Michael

    2011-12-01

    s-Triazine herbicides are widely used for weed control, and are persistent in soils. Nitrification is an essential process in the global nitrogen cycle in soil, and involves ammonia-oxidizing Bacteria (AOB) and ammonia-oxidizing Archaea (AOA). In this study, we evaluated the effect of the s-triazine herbicide simazine on the nitrification and on the structure of ammonia-oxidizing microbial communities in a fertilized agricultural soil. The effect of simazine on AOB and AOA were studied by PCR-amplification of amoA genes of nitrifying Bacteria and Archaea in soil microcosms and denaturing gradient gel electrophoresis (DGGE) analyses. Simazine [50 μg g(-1) dry weight soil (d.w.s)] completely inhibited the nitrification processes in the fertilized agricultural soil. The inhibition by simazine of ammonia oxidation observed was similar to the reduction of ammonia oxidation by the nitrification inhibitor acetylene. The application of simazine-affected AOB community DGGE patterns in the agricultural soil amended with ammonium, whereas no significant changes in the AOA community were observed. The DGGE analyses strongly suggest that simazine inhibited Nitrosobacteria and specifically Nitrosospira species. In conclusion, our results suggest that the s-triazine herbicide not only inhibits the target susceptible plants but also inhibits the ammonia oxidation and the AOB in fertilized soils. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  18. Relationship between oxidative stress and brain swelling in goldfish (Carassius auratus) exposed to high environmental ammonia.

    PubMed

    Lisser, David F J; Lister, Zachary M; Pham-Ho, Phillip Q H; Scott, Graham R; Wilkie, Michael P

    2017-01-01

    Buildups of ammonia can cause potentially fatal brain swelling in mammals, but such swelling is reversible in the anoxia- and ammonia-tolerant goldfish (Carassius auratus). We investigated brain swelling and its possible relationship to oxidative stress in the brain and liver of goldfish acutely exposed to high external ammonia (HEA; 5 mmol/l NH 4 Cl) at two different acclimation temperatures (14°C, 4°C). Exposure to HEA at 14°C for 72h resulted in increased internal ammonia and glutamine concentrations in the brain, and it caused cellular oxidative damage in the brain and liver. However, oxidative damage was most pronounced in brain, in which there was a twofold increase in thiobarbituric acid-reactive substances, a threefold increase in protein carbonylation, and a 20% increase in water volume (indicative of brain swelling). Increased activities of catalase, glutathione peroxidase, and glutathione reductase in the brain suggested that goldfish upregulate their antioxidant capacity to partially offset oxidative stress during hyperammonemia at 14°C. Notably, acclimation to colder (4°C) water completely attenuated the oxidative stress response to HEA in both tissues, and there was no change in brain water volume despite similar increases in internal ammonia. We suggest that ammonia-induced oxidative stress may be responsible for the swelling of goldfish brain during HEA, but further studies are needed to establish a mechanistic link between reactive oxygen species production and brain swelling. Nevertheless, a high capacity to withstand oxidative stress in response to variations in internal ammonia likely explains why goldfish are more resilient to this stressor than most other vertebrates. Copyright © 2017 the American Physiological Society.

  19. Relationship between oxidative stress and brain swelling in goldfish (Carassius auratus) exposed to high environmental ammonia

    PubMed Central

    Lisser, David F. J.; Lister, Zachary M.; Pham-Ho, Phillip Q. H.; Scott, Graham R.

    2017-01-01

    Buildups of ammonia can cause potentially fatal brain swelling in mammals, but such swelling is reversible in the anoxia- and ammonia-tolerant goldfish (Carassius auratus). We investigated brain swelling and its possible relationship to oxidative stress in the brain and liver of goldfish acutely exposed to high external ammonia (HEA; 5 mmol/l NH4Cl) at two different acclimation temperatures (14°C, 4°C). Exposure to HEA at 14°C for 72h resulted in increased internal ammonia and glutamine concentrations in the brain, and it caused cellular oxidative damage in the brain and liver. However, oxidative damage was most pronounced in brain, in which there was a twofold increase in thiobarbituric acid–reactive substances, a threefold increase in protein carbonylation, and a 20% increase in water volume (indicative of brain swelling). Increased activities of catalase, glutathione peroxidase, and glutathione reductase in the brain suggested that goldfish upregulate their antioxidant capacity to partially offset oxidative stress during hyperammonemia at 14°C. Notably, acclimation to colder (4°C) water completely attenuated the oxidative stress response to HEA in both tissues, and there was no change in brain water volume despite similar increases in internal ammonia. We suggest that ammonia-induced oxidative stress may be responsible for the swelling of goldfish brain during HEA, but further studies are needed to establish a mechanistic link between reactive oxygen species production and brain swelling. Nevertheless, a high capacity to withstand oxidative stress in response to variations in internal ammonia likely explains why goldfish are more resilient to this stressor than most other vertebrates. PMID:27784686

  20. Nitrification of archaeal ammonia oxidizers in acid soils is supported by hydrolysis of urea

    PubMed Central

    Lu, Lu; Han, Wenyan; Zhang, Jinbo; Wu, Yucheng; Wang, Baozhan; Lin, Xiangui; Zhu, Jianguo; Cai, Zucong; Jia, Zhongjun

    2012-01-01

    The hydrolysis of urea as a source of ammonia has been proposed as a mechanism for the nitrification of ammonia-oxidizing bacteria (AOB) in acidic soil. The growth of Nitrososphaera viennensis on urea suggests that the ureolysis of ammonia-oxidizing archaea (AOA) might occur in natural environments. In this study, 15N isotope tracing indicates that ammonia oxidation occurred upon the addition of urea at a concentration similar to the in situ ammonium content of tea orchard soil (pH 3.75) and forest soil (pH 5.4) and was inhibited by acetylene. Nitrification activity was significantly stimulated by urea fertilization and coupled well with abundance changes in archaeal amoA genes in acidic soils. Pyrosequencing of 16S rRNA genes at whole microbial community level demonstrates the active growth of AOA in urea-amended soils. Molecular fingerprinting further shows that changes in denaturing gradient gel electrophoresis fingerprint patterns of archaeal amoA genes are paralleled by nitrification activity changes. However, bacterial amoA and 16S rRNA genes of AOB were not detected. The results strongly suggest that archaeal ammonia oxidation is supported by hydrolysis of urea and that AOA, from the marine Group 1.1a-associated lineage, dominate nitrification in two acidic soils tested. PMID:22592820

  1. Nitrification of archaeal ammonia oxidizers in acid soils is supported by hydrolysis of urea.

    PubMed

    Lu, Lu; Han, Wenyan; Zhang, Jinbo; Wu, Yucheng; Wang, Baozhan; Lin, Xiangui; Zhu, Jianguo; Cai, Zucong; Jia, Zhongjun

    2012-10-01

    The hydrolysis of urea as a source of ammonia has been proposed as a mechanism for the nitrification of ammonia-oxidizing bacteria (AOB) in acidic soil. The growth of Nitrososphaera viennensis on urea suggests that the ureolysis of ammonia-oxidizing archaea (AOA) might occur in natural environments. In this study, (15)N isotope tracing indicates that ammonia oxidation occurred upon the addition of urea at a concentration similar to the in situ ammonium content of tea orchard soil (pH 3.75) and forest soil (pH 5.4) and was inhibited by acetylene. Nitrification activity was significantly stimulated by urea fertilization and coupled well with abundance changes in archaeal amoA genes in acidic soils. Pyrosequencing of 16S rRNA genes at whole microbial community level demonstrates the active growth of AOA in urea-amended soils. Molecular fingerprinting further shows that changes in denaturing gradient gel electrophoresis fingerprint patterns of archaeal amoA genes are paralleled by nitrification activity changes. However, bacterial amoA and 16S rRNA genes of AOB were not detected. The results strongly suggest that archaeal ammonia oxidation is supported by hydrolysis of urea and that AOA, from the marine Group 1.1a-associated lineage, dominate nitrification in two acidic soils tested.

  2. Ammonia oxidation driven by archaea rather than bacteria in the hot spring at Tengchong geothermal field, China.

    NASA Astrophysics Data System (ADS)

    Chen, Shun; Peng, Xiaotong; Xu, Hengchao; Li, Jiwei; Ta, Kaiwen

    2015-04-01

    The occurrence of microbial mediated ammonia oxidation and these organisms are present in large numbers in natural environments indicated a potential biogeochemical role for them in the global nitrogen cycle. However, very little is understood about their role and contribution to nitrification in the high temperature extreme environments. Here we explore the ammonia oxidation rates and abundance of potential ammonia-oxidizing archaea (AOA) in upper and bottom sediments from Gongxiaoshe hot spring, Tengchong, Yunnan, China. The 15N-incorporating AOA cells and cell aggregated were detected with Fluorescence in situ hybridization (FISH) and Nano secondary ion mass spectrometry (Nano-SIMS). Ammonia oxidation rates measured using 15N-NO3- pool dilution in upper and bottom sediments (without NH4+ stimulated) were 4.8 and 5.3 nmol N g-1h-1, respectively. Close relatives of the autotrophic, ammonia-oxidizing archaeon 'Candidatus Nitrosocaldus yellowstonii' represented the most abundant OTU in both of the two spring sediments by 16S rRNA gene analysis. Furthermore, it should be noted that no ammonia-oxidizing bacterial clones detected in this study. Quantitative PCR (qPCR) indicated that AOA and 16S rRNA genes were present at 2.75-9.80×105 and 0.128-1.96×108 gene copies g-1 sediment. Based on the reaction rates and AOA abundance, we estimated the cell-specific nitrification rates were 0.41 to 0.79 fmol N archaeal cell-1 h-1, which are comparable to those observed in estuary environment. We suggest that AOA have the responsibility in nitrification in this hot spring, and these archaea rather than bacteria may be considered as a driver in nitrogen cycling in terrestrial hot ecosystems. Key words: ammonia-oxidizing archaea (AOA); nitrification; ammonia-oxidizing rate; hot spring;

  3. Community structure of ammonia-oxidizing archaea and ammonia-oxidizing bacteria in soil treated with the insecticide imidacloprid.

    PubMed

    Cycoń, Mariusz; Piotrowska-Seget, Zofia

    2015-01-01

    The purpose of this experiment was to assess the effect of imidacloprid on the community structure of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in soil using the denaturing gradient gel electrophoresis (DGGE) approach. Analysis showed that AOA and AOB community members were affected by the insecticide treatment. However, the calculation of the richness (S) and the Shannon-Wiener index (H) values for soil treated with the field rate (FR) dosage of imidacloprid (1 mg/kg soil) showed no changes in measured indices for the AOA and AOB community members. In turn, the 10∗FR dosage of insecticide (10 mg/kg soil) negatively affected the AOA community, which was confirmed by the decrease of the S and H values in comparison with the values obtained for the control soil. In the case of AOB community, an initial decline followed by the increase of the S and H values was obtained. Imidacloprid decreased the nitrification rate while the ammonification process was stimulated by the addition of imidacloprid. Changes in the community structure of AOA and AOB could be due to an increase in the concentration of N-NH4 (+), known as the most important factor which determines the contribution of these microorganisms to soil nitrification.

  4. Community Structure of Ammonia-Oxidizing Archaea and Ammonia-Oxidizing Bacteria in Soil Treated with the Insecticide Imidacloprid

    PubMed Central

    Cycoń, Mariusz; Piotrowska-Seget, Zofia

    2015-01-01

    The purpose of this experiment was to assess the effect of imidacloprid on the community structure of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in soil using the denaturing gradient gel electrophoresis (DGGE) approach. Analysis showed that AOA and AOB community members were affected by the insecticide treatment. However, the calculation of the richness (S) and the Shannon-Wiener index (H) values for soil treated with the field rate (FR) dosage of imidacloprid (1 mg/kg soil) showed no changes in measured indices for the AOA and AOB community members. In turn, the 10∗FR dosage of insecticide (10 mg/kg soil) negatively affected the AOA community, which was confirmed by the decrease of the S and H values in comparison with the values obtained for the control soil. In the case of AOB community, an initial decline followed by the increase of the S and H values was obtained. Imidacloprid decreased the nitrification rate while the ammonification process was stimulated by the addition of imidacloprid. Changes in the community structure of AOA and AOB could be due to an increase in the concentration of N-NH4 +, known as the most important factor which determines the contribution of these microorganisms to soil nitrification. PMID:25705674

  5. Genome Sequence of an Ammonia-Oxidizing Soil Archaeon, “Candidatus Nitrosoarchaeum koreensis” MY1

    PubMed Central

    Kim, Byung Kwon; Jung, Man-Young; Yu, Dong Su; Park, Soo-Je; Oh, Tae Kwang; Rhee, Sung-Keun; Kim, Jihyun F.

    2011-01-01

    Ammonia-oxidizing archaea are ubiquitous microorganisms which play important roles in global nitrogen and carbon cycle on earth. Here we present the high-quality draft genome sequence of an ammonia-oxidizing archaeon, “Candidatus Nitrosopumilus koreensis” MY1, that dominated an enrichment culture of a soil sample from the rhizosphere. Its genome contains genes for survival in the rhizosphere environment as well as those for carbon fixation and ammonium oxidation to nitrite. PMID:21914867

  6. Community composition of ammonia-oxidizing archaea from surface and anoxic depths of oceanic oxygen minimum zones.

    PubMed

    Peng, Xuefeng; Jayakumar, Amal; Ward, Bess B

    2013-01-01

    Ammonia-oxidizing archaea (AOA) have been reported at high abundance in much of the global ocean, even in environments, such as pelagic oxygen minimum zones (OMZs), where conditions seem unlikely to support aerobic ammonium oxidation. Due to the lack of information on any potential alternative metabolism of AOA, the AOA community composition might be expected to differ between oxic and anoxic environments. This hypothesis was tested by evaluating AOA community composition using a functional gene microarray that targets the ammonia monooxygenase gene subunit A (amoA). The relationship between environmental parameters and the biogeography of the Arabian Sea and the Eastern Tropical South Pacific (ETSP) AOA assemblages was investigated using principal component analysis (PCA) and redundancy analysis (RDA). In both the Arabian Sea and the ETSP, AOA communities within the core of the OMZ were not significantly different from those inhabiting the oxygenated surface waters above the OMZ. The AOA communities in the Arabian Sea were significantly different from those in the ETSP. In both oceans, the abundance of archaeal amoA gene in the core of the OMZ was higher than that in the surface waters. Our results indicate that AOA communities are distinguished by their geographic origin. RDA suggested that temperature (higher in the Arabian Sea than in the ETSP) was the main factor that correlated with the differences between the AOA communities. Physicochemical properties that characterized the different environments of the OMZ and surface waters played a less important role, than did geography, in shaping the AOA community composition.

  7. Low-temperature conversion of ammonia to nitrogen in water with ozone over composite metal oxide catalyst.

    PubMed

    Chen, Yunnen; Wu, Ye; Liu, Chen; Guo, Lin; Nie, Jinxia; Chen, Yu; Qiu, Tingsheng

    2018-04-01

    As one of the most important water pollutants, ammonia nitrogen emissions have increased year by year, which has attracted people's attention. Catalytic ozonation technology, which involves production of ·OH radical with strong oxidation ability, is widely used in the treatment of organic-containing wastewater. In this work, MgO-Co 3 O 4 composite metal oxide catalysts prepared with different fabrication conditions have been systematically evaluated and compared in the catalytic ozonation of ammonia (50mg/L) in water. In terms of high catalytic activity in ammonia decomposition and high selectivity for gaseous nitrogen, the catalyst with MgO-Co 3 O 4 molar ratio 8:2, calcined at 500°C for 3hr, was the best one among the catalysts we tested, with an ammonia nitrogen removal rate of 85.2% and gaseous nitrogen selectivity of 44.8%. In addition, the reaction mechanism of ozonation oxidative decomposition of ammonia nitrogen in water with the metal oxide catalysts was discussed. Moreover, the effect of coexisting anions on the degradation of ammonia was studied, finding that SO 4 2- and HCO 3 - could inhibit the catalytic activity while CO 3 2- and Br - could promote it. The presence of coexisting cations had very little effect on the catalytic ozonation of ammonia nitrogen. After five successive reuses, the catalyst remained stable in the catalytic ozonation of ammonia. Copyright © 2017. Published by Elsevier B.V.

  8. Gas-exfoliated porous monolayer boron nitride for enhanced aerobic oxidative desulfurization performance.

    PubMed

    Wu, Yingcheng; Wu, Peiwen; Chao, Yanhong; He, Jing; Li, Hongping; Lu, Linjie; Jiang, Wei; Zhang, Beibei; Li, Huaming; Zhu, Wenshuai

    2018-01-12

    Hexagonal boron nitride has been regarded to be an efficient catalyst in aerobic oxidation fields, but limited by the less-exposed active sites. In this contribution, we proposed a simple green liquid nitrogen gas exfoliation strategy for preparation of porous monolayer nanosheets (BN-1). Owing to the reduced layer numbers, decreased lateral sizes and artificially-constructed pores, increased exposure of active sites was expected, further contributed to an enhanced aerobic oxidative desulfurization (ODS) performance up to ∼98% of sulfur removal, achieving ultra-deep desulfurization. This work not only introduced an excellent catalyst for aerobic ODS, but also provided a strategy for construction of some other highly-efficient monolayer two-dimensional materials for enhanced catalytic performance.

  9. Gas-exfoliated porous monolayer boron nitride for enhanced aerobic oxidative desulfurization performance

    NASA Astrophysics Data System (ADS)

    Wu, Yingcheng; Wu, Peiwen; Chao, Yanhong; He, Jing; Li, Hongping; Lu, Linjie; Jiang, Wei; Zhang, Beibei; Li, Huaming; Zhu, Wenshuai

    2018-01-01

    Hexagonal boron nitride has been regarded to be an efficient catalyst in aerobic oxidation fields, but limited by the less-exposed active sites. In this contribution, we proposed a simple green liquid nitrogen gas exfoliation strategy for preparation of porous monolayer nanosheets (BN-1). Owing to the reduced layer numbers, decreased lateral sizes and artificially-constructed pores, increased exposure of active sites was expected, further contributed to an enhanced aerobic oxidative desulfurization (ODS) performance up to ˜98% of sulfur removal, achieving ultra-deep desulfurization. This work not only introduced an excellent catalyst for aerobic ODS, but also provided a strategy for construction of some other highly-efficient monolayer two-dimensional materials for enhanced catalytic performance.

  10. EXAMINING THE TEMPORAL VARIABILITY OF AMMONIA AND NITRIC OXIDE EMISSIONS FROM AGRICULTURAL PROCESSES

    EPA Science Inventory

    This paper examines the temporal variability of airborne emissions of ammonia from livestock operations and fertilizer application and nitric oxide from soils. In the United States, the livestock operations and fertilizer categories comprise the majority of the ammonia emissions...

  11. Room temperature aerobic oxidation of amines by a nanocrystalline ruthenium oxide pyrochlore nafion composite catalyst.

    PubMed

    Venkatesan, Shanmuganathan; Kumar, Annamalai Senthil; Lee, Jyh-Fu; Chan, Ting-Shan; Zen, Jyh-Myng

    2012-05-14

    The aerobic oxidation of primary amines to their respective nitriles has been carried out at room temperature using a highly reusable nanocrystalline ruthenium oxide pyrochlore Nafion composite catalyst (see figure). Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. pH regulates ammonia-oxidizing bacteria and archaea in paddy soils in Southern China.

    PubMed

    Li, Hu; Weng, Bo-Sen; Huang, Fu-Yi; Su, Jian-Qiang; Yang, Xiao-Ru

    2015-07-01

    Ammonia-oxidizing archaea (AOA) and bacteria (AOB) play important roles in nitrogen cycling. However, the effects of environmental factors on the activity, abundance, and diversity of AOA and AOB and the relative contributions of these two groups to nitrification in paddy soils are not well explained. In this study, potential nitrification activity (PNA), abundance, and diversity of amoA genes from 12 paddy soils in Southern China were determined by potential nitrification assay, quantitative PCR, and cloning. The results showed that PNA was highly variable between paddy soils, ranging from 4.05 ± 0.21 to 9.81 ± 1.09 mg NOx-N kg(-1) dry soil day(-1), and no significant correlation with soil parameters was found. The abundance of AOA was predominant over AOB, indicating that AOA may be the major members in aerobic ammonia oxidation in these paddy soils. Community compositions of AOA and AOB were highly variable among samples, but the variations were best explained by pH. AOA sequences were affiliated to the Nitrosopumilus cluster and Nitrososphaera cluster, and AOB were classified into the lineages of Nitrosospira and Nitrosomonas, with Nitrosospira being predominant over Nitrosomonas, accounting for 83.6 % of the AOB community. Moreover, the majority of Nitrosomonas was determined in neutral soils. Canonical correspondence analysis (CCA) analysis further demonstrated that AOA and AOB community structures were significantly affected by pH, soil total organic carbon, total nitrogen, and C/N ratio, suggesting that these factors exert strong effects on the distribution of AOB and AOA in paddy soils in Southern China. In conclusion, our results imply that soil pH was a key explanatory variable for both AOA and AOB community structure and nitrification activity.

  13. Microbial acceleration of aerobic pyrite oxidation at circumneutral pH.

    PubMed

    Percak-Dennett, E; He, S; Converse, B; Konishi, H; Xu, H; Corcoran, A; Noguera, D; Chan, C; Bhattacharyya, A; Borch, T; Boyd, E; Roden, E E

    2017-09-01

    Pyrite (FeS 2 ) is the most abundant sulfide mineral on Earth and represents a significant reservoir of reduced iron and sulfur both today and in the geologic past. In modern environments, oxidative transformations of pyrite and other metal sulfides play a key role in terrestrial element partitioning with broad impacts to contaminant mobility and the formation of acid mine drainage systems. Although the role of aerobic micro-organisms in pyrite oxidation under acidic-pH conditions is well known, to date there is very little known about the capacity for aerobic micro-organisms to oxidize pyrite at circumneutral pH. Here, we describe two enrichment cultures, obtained from pyrite-bearing subsurface sediments, that were capable of sustained cell growth linked to pyrite oxidation and sulfate generation at neutral pH. The cultures were dominated by two Rhizobiales species (Bradyrhizobium sp. and Mesorhizobium sp.) and a Ralstonia species. Shotgun metagenomic sequencing and genome reconstruction indicated the presence of Fe and S oxidation pathways in these organisms, and the presence of a complete Calvin-Benson-Bassham CO 2 fixation system in the Bradyrhizobium sp. Oxidation of pyrite resulted in thin (30-50 nm) coatings of amorphous Fe(III) oxide on the pyrite surface, with no other secondary Fe or S phases detected by electron microscopy or X-ray absorption spectroscopy. Rates of microbial pyrite oxidation were approximately one order of magnitude higher than abiotic rates. These results demonstrate the ability of aerobic microbial activity to accelerate pyrite oxidation and expand the potential contribution of micro-organisms to continental sulfide mineral weathering around the time of the Great Oxidation Event to include neutral-pH environments. In addition, our findings have direct implications for the geochemistry of modern sedimentary environments, including stimulation of the early stages of acid mine drainage formation and mobilization of pyrite

  14. Cultivation and characterization of Candidatus Nitrosocosmicus exaquare, an ammonia-oxidizing archaeon from a municipal wastewater treatment system

    PubMed Central

    Sauder, Laura A; Albertsen, Mads; Engel, Katja; Schwarz, Jasmin; Nielsen, Per H; Wagner, Michael; Neufeld, Josh D

    2017-01-01

    Thaumarchaeota have been detected in several industrial and municipal wastewater treatment plants (WWTPs), despite the fact that ammonia-oxidizing archaea (AOA) are thought to be adapted to low ammonia environments. However, the activity, physiology and metabolism of WWTP-associated AOA remain poorly understood. We report the cultivation and complete genome sequence of Candidatus Nitrosocosmicus exaquare, a novel AOA representative from a municipal WWTP in Guelph, Ontario (Canada). In enrichment culture, Ca. N. exaquare oxidizes ammonia to nitrite stoichiometrically, is mesophilic, and tolerates at least 15 mm of ammonium chloride or sodium nitrite. Microautoradiography (MAR) for enrichment cultures demonstrates that Ca. N. exaquare assimilates bicarbonate in association with ammonia oxidation. However, despite using inorganic carbon, the ammonia-oxidizing activity of Ca. N. exaquare is greatly stimulated in enrichment culture by the addition of organic compounds, especially malate and succinate. Ca. N. exaquare cells are coccoid with a diameter of ~1–2 μm. Phylogenetically, Ca. N. exaquare belongs to the Nitrososphaera sister cluster within the Group I.1b Thaumarchaeota, a lineage which includes most other reported AOA sequences from municipal and industrial WWTPs. The 2.99 Mbp genome of Ca. N. exaquare encodes pathways for ammonia oxidation, bicarbonate fixation, and urea transport and breakdown. In addition, this genome encodes several key genes for dealing with oxidative stress, including peroxidase and catalase. Incubations of WWTP biofilm demonstrate partial inhibition of ammonia-oxidizing activity by 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (PTIO), suggesting that Ca. N. exaquare-like AOA may contribute to nitrification in situ. However, CARD-FISH-MAR showed no incorporation of bicarbonate by detected Thaumarchaeaota, suggesting that detected AOA may incorporate non-bicarbonate carbon sources or rely on an alternative and yet unknown

  15. Simple Copper Catalysts for the Aerobic Oxidation of Amines: Selectivity Control by the Counterion.

    PubMed

    Xu, Boran; Hartigan, Elizabeth M; Feula, Giancarlo; Huang, Zheng; Lumb, Jean-Philip; Arndtsen, Bruce A

    2016-12-19

    We describe the use of simple copper-salt catalysts in the selective aerobic oxidation of amines to nitriles or imines. These catalysts are marked by their exceptional efficiency, operate at ambient temperature and pressure, and allow the oxidation of amines without expensive ligands or additives. This study highlights the significant role counterions can play in controlling selectivity in catalytic aerobic oxidations. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Enhanced heme protein expression by ammonia-oxidizing communities acclimated to low dissolved oxygen conditions.

    PubMed

    Arnaldos, Marina; Kunkel, Stephanie A; Stark, Benjamin C; Pagilla, Krishna R

    2013-12-01

    This study has investigated the acclimation of ammonia-oxidizing communities (AOC) to low dissolved oxygen (DO) concentrations. Under controlled laboratory conditions, two sequencing batch reactors seeded with activated sludge from the same source were operated at high DO (near saturation) and low DO (0.1 mg O₂/L) concentrations for a period of 220 days. The results demonstrated stable and complete nitrification at low DO conditions after an acclimation period of approximately 140 days. Acclimation brought about increased specific oxygen uptake rates and enhanced expression of a particular heme protein in the soluble fraction of the cells in the low DO reactor as compared to the high DO reactor. The induced protein was determined not to be any of the enzymes or electron carriers present in the conventional account of ammonia oxidation in ammonia-oxidizing bacteria (AOB). Further research is required to determine the specific nature of the heme protein detected; a preliminary assessment suggests either a type of hemoglobin protein or a lesser-known component of the energy-transducing pathways of AOB. The effect of DO on AOC dynamics was evaluated using the 16S rRNA gene as the basis for phylogenetic comparisons and organism quantification. Ammonium consumption by ammonia-oxidizing archaea and anaerobic ammonia-oxidizing bacteria was ruled out by fluorescent in situ hybridization in both reactors. Even though Nitrosomonas europaea was the dominant AOB lineage in both high and low DO sequencing batch reactors at the end of operation, this enrichment could not be linked in the low DO reactor to acclimation to oxygen-limited conditions.

  17. Characteristics of two novel cold- and salt-tolerant ammonia-oxidizing bacteria from Liaohe Estuarine Wetland.

    PubMed

    Huang, Xiao; Bai, Jie; Li, Kui-Ran; Zhao, Yang-Guo; Tian, Wei-Jun; Dang, Jia-Jia

    2017-01-15

    To achieve a better contaminant removal efficiency in a low-temperature and high-salt environment, two novel strains of cold- and salt-tolerant ammonia-oxidizing bacteria (AOB), i.e., Ochrobactrum sp. (HXN-1) and Aquamicrobium sp. (HXN-2), were isolated from the surface sediment of Liaohe Estuarine Wetland (LEW), China. The optimization of initial ammonia nitrogen concentration, pH, carbon-nitrogen ratio, and petroleum hydrocarbons (PHCs) to improve the ammonia-oxidation capacity of the two bacterial strains was studied. Both bacterial strains showed a high ammonia nitrogen removal rate of over 80% under a high salinity of 10‰. Even at a temperature as low as 15°C, HXN-1 and HXN-2 could achieve an ammonia nitrogen removal rate of 53% and 62%, respectively. The cold- and salt-tolerant AOB in this study demonstrated a high potential for ammonia nitrogen removal from LEW. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Species, Abundance and Function of Ammonia-oxidizing Archaea in Inland Waters across China

    NASA Astrophysics Data System (ADS)

    Zhou, Leiliu; Wang, Shanyun; Zou, Yuxuan; Xia, Chao; Zhu, Guibing

    2015-11-01

    Ammonia oxidation is the first step in nitrification and was thought to be performed solely by specialized bacteria. The discovery of ammonia-oxidizing archaea (AOA) changed this view. We examined the large scale and spatio-temporal occurrence, abundance and role of AOA throughout Chinese inland waters (n = 28). Molecular survey showed that AOA was ubiquitous in inland waters. The existence of AOA in extreme acidic, alkaline, hot, cold, eutrophic and oligotrophic environments expanded the tolerance limits of AOA, especially their known temperature tolerance to -25 °C, and substrate load to 42.04 mM. There were spatio-temporal divergences of AOA community structure in inland waters, and the diversity of AOA in inland water ecosystems was high with 34 observed species-level operational taxonomic units (OTUs; based on a 15% cutoff) distributed widely in group I.1b, I.1a, and I.1a-associated. The abundance of AOA was quite high (8.5 × 104 to 8.5 × 109 copies g-1), and AOA outnumbered ammonia-oxidizing bacteria (AOB) in the inland waters where little human activities were involved. On the whole AOB predominate the ammonia oxidation rate over AOA in inland water ecosystems, and AOA play an indispensable role in global nitrogen cycle considering that AOA occupy a broader habitat range than AOB, especially in extreme environments.

  19. Application of a Chemiluminescence Detector for the Measurement of Total Oxides of Nitrogen and Ammonia in the Atmosphere

    NASA Technical Reports Server (NTRS)

    Hodgeson, J. A.; Bell, J. P.; Rehme, K. A.; Krost, K. J.; Stevens, R. K.

    1971-01-01

    By means of the thermal conversion of nitrogen dioxide to the nitric oxide, the chemiluminescent nitric oxide monitor, based on the nitric oxide plus ozone reaction, may be used for monitoring nitrogen dioxide plus nitric oxide (NO(x)). Under conditions previously described, ammonia is also converted to nitric oxide and therefore interferes. A metal surface, gold wool or stainless steel, operated at two different temperatures has been used to convert only nitrogen dioxide or nitrogen dioxide plus ammonia. Quantitative conversion of nitrogen dioxide to nitric oxide has been obtained at temperatures as low as 200 C. Conversion of ammonia is effected at temperatures of 300 C or higher. By the addition of a converter the basic nitric oxide monitor may be used for measuring NO(x) or NO(x) plus ammonia. As an alternate mode, for a fixed high temperature, a specific scrubber is described for removing NH3 without affecting NO2 concentrations.

  20. [Microbial diversity and ammonia-oxidizing microorganism of a soil sample near an acid mine drainage lake].

    PubMed

    Liu, Ying; Wang, Li-Hua; Hao, Chun-Bo; Li, Lu; Li, Si-Yuan; Feng, Chuan-Ping

    2014-06-01

    The main physicochemical parameters of the soil sample which was collected near an acid mine drainage reservoir in Anhui province was analyzed. The microbial diversity and community structure was studied through the construction of bacteria and archaea 16S rRNA gene clone libraries and ammonia monooxygenase gene clone library of archaea. The functional groups which were responsible for the process of ammonia oxidation were also discussed. The results indicated that the soil sample had extreme low pH value (pH < 3) and high ions concentration, which was influenced by the acid mine drainage (AMD). All the 16S rRNA gene sequences of bacteria clone library fell into 11 phyla, and Acidobacteria played the most significant role in the ecosystem followed by Verrucomicrobia. A great number of acidophilic bacteria existed in the soil sample, such as Candidatus Koribacter versatilis and Holophaga sp.. The archaea clone library consisted of 2 phyla (Thaumarchaeota and Euryarchaeota). The abundance of Thaumarchaeota was remarkably higher than Euryarchaeota. The ammonia oxidation in the soil environment was probably driven by ammonia-oxidizing archaea, and new species of ammonia-oxidizing archaea existed in the soil sample.

  1. Ammonia oxidation is not required for growth of Group 1.1c soil Thaumarchaeota

    PubMed Central

    Weber, Eva B.; Lehtovirta-Morley, Laura E.; Prosser, James I.; Gubry-Rangin, Cécile

    2015-01-01

    Thaumarchaeota are among the most abundant organisms on Earth and are ubiquitous. Within this phylum, all cultivated representatives of Group 1.1a and Group 1.1b Thaumarchaeota are ammonia oxidizers, and play a key role in the nitrogen cycle. While Group 1.1c is phylogenetically closely related to the ammonia-oxidizing Thaumarchaeota and is abundant in acidic forest soils, nothing is known about its physiology or ecosystem function. The goal of this study was to perform in situ physiological characterization of Group 1.1c Thaumarchaeota by determining conditions that favour their growth in soil. Several acidic grassland, birch and pine tree forest soils were sampled and those with the highest Group 1.1c 16S rRNA gene abundance were incubated in microcosms to determine optimal growth temperature, ammonia oxidation and growth on several organic compounds. Growth of Group 1.1c Thaumarchaeota, assessed by qPCR of Group 1.1c 16S rRNA genes, occurred in soil, optimally at 30°C, but was not associated with ammonia oxidation and the functional gene amoA could not be detected. Growth was also stimulated by addition of organic nitrogen compounds (glutamate and casamino acids) but not when supplemented with organic carbon alone. This is the first evidence for non-ammonia oxidation associated growth of Thaumarchaeota in soil. PMID:25764563

  2. Nitric oxide is an obligate bacterial nitrification intermediate produced by hydroxylamine oxidoreductase.

    PubMed

    Caranto, Jonathan D; Lancaster, Kyle M

    2017-08-01

    Ammonia (NH 3 )-oxidizing bacteria (AOB) emit substantial amounts of nitric oxide (NO) and nitrous oxide (N 2 O), both of which contribute to the harmful environmental side effects of large-scale agriculture. The currently accepted model for AOB metabolism involves NH 3 oxidation to nitrite (NO 2 - ) via a single obligate intermediate, hydroxylamine (NH 2 OH). Within this model, the multiheme enzyme hydroxylamine oxidoreductase (HAO) catalyzes the four-electron oxidation of NH 2 OH to NO 2 - We provide evidence that HAO oxidizes NH 2 OH by only three electrons to NO under both anaerobic and aerobic conditions. NO 2 - observed in HAO activity assays is a nonenzymatic product resulting from the oxidation of NO by O 2 under aerobic conditions. Our present study implies that aerobic NH 3 oxidation by AOB occurs via two obligate intermediates, NH 2 OH and NO, necessitating a mediator of the third enzymatic step.

  3. Effects of aerobic training on exercise-related oxidative stress in mitochondrial myopathies.

    PubMed

    Siciliano, Gabriele; Simoncini, Costanza; Lo Gerfo, Annalisa; Orsucci, Daniele; Ricci, Giulia; Mancuso, Michelangelo

    2012-12-01

    In mitochondrial myopathies with respiratory chain deficiency impairment of energy cell production may lead to in excess reactive oxygen species generation with consequent oxidative stress and cell damage. Aerobic training has been showed to increase muscle performance in patients with mitochondrial myopathies. Aim of this study has been to evaluate, in 7 patients (6 F e 1M, mean age 44.9 ± 12.1 years) affected by mitochondrial disease, concomitantly to lactate exercise curve, the occurrence of oxidative stress, as indicated by circulating levels of lipoperoxides, in rest condition and as effect of exercise, and also, to verify if an aerobic training program is able to modify, in these patients, ox-redox balance efficiency. At rest and before training blood level of lipoperoxides was 382.4 ± 37.8 AU, compared to controls (318.7 ± 63.8; P<0.05), this corresponding to a moderate oxidative stress degree according to the adopted scale. During incremental exercise blood level of lipoperoxides did not increase, but maintained significantly higher compared to controls. After an aerobic training of 10 weeks the blood level of lipoperoxides decreased by 13.7% at rest (P<0.01) and 10.4%, 8.6% and 8.5% respectively at the corresponding times during the exercise test (P=0.06). These data indicate that, in mitochondrial patients, oxidative stress occurs and that an aerobic training is useful in partially reverting this condition. Copyright © 2012 Elsevier B.V. All rights reserved.

  4. [Effect of lignite humic acid on soil ammonia oxidizing archaea community].

    PubMed

    Dong, Lianhua; Li, Baozhen; Yuan, Hongli; Scow, Kate M

    2010-06-01

    To illuminate the impact of humic acid (HA) on soil ammonia oxidizing archaea and then reveal the effect of HA on soil nitrogen cycle. Two humic acids (cHA and bHA) were added into the soil amended with urea. Community changes of ammonia oxidizing archaea (AOA) and total archaea were studied with terminal restricted fragment length polymorphism (T-RFLP) and real time PCR in the microcosm experiment. We found that the AOA population size increased significantly and AOA community changed greatly in the urea only treatment. However, HA could inhibit the increase of AOA population, moreover, HA could buffer the change in AOA community showed by canonical correspondence analysis (CCA) result. On the other hand, the total archaeal population decreased significantly in the urea only treatment, but stabilized in the urea with HA treatments, which indicated HA could eliminate the toxicity of urea to total archaea. CCA results showed that incubation time was the most important factor for the total archaeal community, and partial CCA (pCCA, when time as a covariable) result demonstrated that cHA was the most important environmental variable for total archaeal community. These results showed that HA diminished ammonia loss by inhibiting the increase of AOA competing with plant for ammonia, thus HA can increase the urea efficiency.

  5. Soil aggregate stratification of nematodes and ammonia oxidizers affects nitrification in an acid soil.

    PubMed

    Jiang, Yuji; Jin, Chen; Sun, Bo

    2014-10-01

    Nitrification plays a central role in global nitrogen cycle, which is affected by interaction between soil microfauna and microorganisms. The impact of synchronized changes in nematodes and ammonia oxidizers within aggregate fractions on nitrification was investigated in an acid soil under 10-year manure application. Nematodes, ammonia oxidizers and potential nitrification activity (PNA) were examined in three soil aggregate fractions under four fertilization regimes. Pyrosequencing data revealed that the dominant bacterial amoA operational taxonomic units (OTUs) were related to Nitrosospira species, while archaeal OTUs were affiliated with Nitrososphaera and Nitrosotalea species. PNA was more strongly correlated with ammonia-oxidizing bacteria (AOB) abundance than ammonia-oxidizing archaea (AOA) abundance, although AOA were dominant in the acid soil. Plant parasites had a negative effect on AOB abundance; however, bacterivores stimulated AOB abundance and contributed more to PNA than plant parasites. Aggregate fractions exerted significant impacts on AOA abundance and AOB community composition. Total carbon content strongly affected the abundance and composition of AOA community, while soil pH primarily affected that of AOB community. Soil variables explained 62.7% and 58.1% variations, and nematode variables explained 11.7% and 19.5% variations in the AOA and AOB community composition respectively. © 2013 Society for Applied Microbiology and John Wiley & Sons Ltd.

  6. Biogeography of anaerobic ammonia-oxidizing (anammox) bacteria.

    PubMed

    Sonthiphand, Puntipar; Hall, Michael W; Neufeld, Josh D

    2014-01-01

    Anaerobic ammonia-oxidizing (anammox) bacteria are able to oxidize ammonia and reduce nitrite to produce N2 gas. After being discovered in a wastewater treatment plant (WWTP), anammox bacteria were subsequently characterized in natural environments, including marine, estuary, freshwater, and terrestrial habitats. Although anammox bacteria play an important role in removing fixed N from both engineered and natural ecosystems, broad scale anammox bacterial distributions have not yet been summarized. The objectives of this study were to explore global distributions and diversity of anammox bacteria and to identify factors that influence their biogeography. Over 6000 anammox 16S rRNA gene sequences from the public database were analyzed in this current study. Data ordinations indicated that salinity was an important factor governing anammox bacterial distributions, with distinct populations inhabiting natural and engineered ecosystems. Gene phylogenies and rarefaction analysis demonstrated that freshwater environments and the marine water column harbored the highest and the lowest diversity of anammox bacteria, respectively. Co-occurrence network analysis indicated that Ca. Scalindua strongly connected with other Ca. Scalindua taxa, whereas Ca. Brocadia co-occurred with taxa from both known and unknown anammox genera. Our survey provides a better understanding of ecological factors affecting anammox bacterial distributions and provides a comprehensive baseline for understanding the relationships among anammox communities in global environments.

  7. Copper-catalyzed aerobic oxidative coupling: From ketone and diamine to pyrazine

    PubMed Central

    Wu, Kun; Huang, Zhiliang; Qi, Xiaotian; Li, Yingzi; Zhang, Guanghui; Liu, Chao; Yi, Hong; Meng, Lingkui; Bunel, Emilio E.; Miller, Jeffrey T.; Pao, Chih-Wen; Lee, Jyh-Fu; Lan, Yu; Lei, Aiwen

    2015-01-01

    Copper-catalyzed aerobic oxidative C–H/N–H coupling between simple ketones and diamines was developed toward the synthesis of a variety of pyrazines. Various substituted ketones were compatible for this transformation. Preliminary mechanistic investigations indicated that radical species were involved. X-ray absorption fine structure experiments elucidated that the Cu(II) species 5 coordinated by two N atoms at a distance of 2.04 Å and two O atoms at a shorter distance of 1.98 Å was a reactive one for this aerobic oxidative coupling reaction. Density functional theory calculations suggested that the intramolecular coupling of cationic radicals was favorable in this transformation. PMID:26601302

  8. pH rather than nitrification and urease inhibitors determines the community of ammonia oxidizers in a vegetable soil.

    PubMed

    Xi, Ruijiao; Long, Xi-En; Huang, Sha; Yao, Huaiying

    2017-12-01

    Nitrification inhibitors and urease inhibitors, such as nitrapyrin and N-(n-butyl) thiophosphoric triamide (NBPT), can improve the efficiencies of nitrogen fertilizers in cropland. However, their effects on ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) across different soil pH levels are still unclear. In the present work, vegetable soils at four pH levels were tested to determine the impacts of nitrification and urease inhibitors on the nitrification activities, abundances and diversities of ammonia oxidizers at different pHs by real-time PCR, terminal restriction fragment length polymorphism (T-RFLP) and clone sequence analysis. The analyses of the abundance of ammonia oxidizers and net nitrification rate suggested that AOA was the dominate ammonia oxidizer and the key driver of nitrification in acidic soil. The relationships between pH and ammonia oxidizer abundance indicated that soil pH dominantly controlled the abundance of AOA but not that of AOB. The T-RFLP results suggested that soil pH could significantly affect the AOA and AOB community structure. Nitrapyrin decreased the net nitrification rate and inhibited the abundance of bacterial amoA genes in this vegetable soil, but exhibited no effect on that of the archaeal amoA genes. In contrast, NBPT just lagged the hydrolysis of urea and kept low NH 4 + -N levels in the soil at the early stage. It exhibited no or slight effects on the abundance and community structure of ammonia oxidizers. These results indicated that soil pH, rather than the application of urea, nitrapyrin and NBPT, was a critical factor influencing the abundance and community structure of AOA and AOB.

  9. A Mesophilic, Autotrophic, Ammonia-Oxidizing Archaeon of Thaumarchaeal Group I.1a Cultivated from a Deep Oligotrophic Soil Horizon

    PubMed Central

    Jung, Man-Young; Park, Soo-Je; Kim, So-Jeong; Kim, Jong-Geol; Sinninghe Damsté, Jaap S.

    2014-01-01

    Soil nitrification plays an important role in the reduction of soil fertility and in nitrate enrichment of groundwater. Various ammonia-oxidizing archaea (AOA) are considered to be members of the pool of ammonia-oxidizing microorganisms in soil. This study reports the discovery of a chemolithoautotrophic ammonia oxidizer that belongs to a distinct clade of nonmarine thaumarchaeal group I.1a, which is widespread in terrestrial environments. The archaeal strain MY2 was cultivated from a deep oligotrophic soil horizon. The similarity of the 16S rRNA gene sequence of strain MY2 to those of other cultivated group I.1a thaumarchaeota members, i.e., Nitrosopumilus maritimus and “Candidatus Nitrosoarchaeum koreensis,” is 92.9% for both species. Extensive growth assays showed that strain MY2 is chemolithoautotrophic, mesophilic (optimum temperature, 30°C), and neutrophilic (optimum pH, 7 to 7.5). The accumulation of nitrite above 1 mM inhibited ammonia oxidation, while ammonia oxidation itself was not inhibited in the presence of up to 5 mM ammonia. The genome size of strain MY2 was 1.76 Mb, similar to those of N. maritimus and “Ca. Nitrosoarchaeum koreensis,” and the repertoire of genes required for ammonia oxidation and carbon fixation in thaumarchaeal group I.1a was conserved. A high level of representation of conserved orthologous genes for signal transduction and motility in the noncore genome might be implicated in niche adaptation by strain MY2. On the basis of phenotypic, phylogenetic, and genomic characteristics, we propose the name “Candidatus Nitrosotenuis chungbukensis” for the ammonia-oxidizing archaeal strain MY2. PMID:24705324

  10. A mesophilic, autotrophic, ammonia-oxidizing archaeon of thaumarchaeal group I.1a cultivated from a deep oligotrophic soil horizon.

    PubMed

    Jung, Man-Young; Park, Soo-Je; Kim, So-Jeong; Kim, Jong-Geol; Sinninghe Damsté, Jaap S; Jeon, Che Ok; Rhee, Sung-Keun

    2014-06-01

    Soil nitrification plays an important role in the reduction of soil fertility and in nitrate enrichment of groundwater. Various ammonia-oxidizing archaea (AOA) are considered to be members of the pool of ammonia-oxidizing microorganisms in soil. This study reports the discovery of a chemolithoautotrophic ammonia oxidizer that belongs to a distinct clade of nonmarine thaumarchaeal group I.1a, which is widespread in terrestrial environments. The archaeal strain MY2 was cultivated from a deep oligotrophic soil horizon. The similarity of the 16S rRNA gene sequence of strain MY2 to those of other cultivated group I.1a thaumarchaeota members, i.e., Nitrosopumilus maritimus and "Candidatus Nitrosoarchaeum koreensis," is 92.9% for both species. Extensive growth assays showed that strain MY2 is chemolithoautotrophic, mesophilic (optimum temperature, 30°C), and neutrophilic (optimum pH, 7 to 7.5). The accumulation of nitrite above 1 mM inhibited ammonia oxidation, while ammonia oxidation itself was not inhibited in the presence of up to 5mM ammonia. The genome size of strain MY2 was 1.76 Mb, similar to those of N. maritimus and "Ca. Nitrosoarchaeum koreensis," and the repertoire of genes required for ammonia oxidation and carbon fixation in thaumarchaeal group I.1a was conserved. A high level of representation of conserved orthologous genes for signal transduction and motility in the noncore genome might be implicated in niche adaptation by strain MY2. On the basis of phenotypic, phylogenetic, and genomic characteristics, we propose the name "Candidatus Nitrosotenuis chungbukensis" for the ammonia-oxidizing archaeal strain MY2.

  11. Ammonia oxidizing archaea are the predominant nitrifiers in disturbed and undisturbed southern US pine forests

    NASA Astrophysics Data System (ADS)

    Mushinski, R. M.; Boutton, T. W.; Gentry, T. J.; Dorosky, R. J.

    2016-12-01

    The rate-limiting step in nitrification, ammonia oxidation, is performed by both ammonia oxidizing bacteria (AOB) and archaea (AOA); however, reports on the relative contribution of each of these groups to forest soil nitrification has varied. We coupled qPCR and next generation sequencing of the amoA gene to a whole-soil assay that stimulates nitrification and allows for the discrimination of AOA- from AOB-activity using 1-octyne, which inhibits the activity of the bacterial ammonia monooxygenase. Soils, to a depth of 1 meter, were collected from replicated (n = 3) loblolly pine (Pinus taeda L.) stands subjected to three different intensities of timber harvest (i.e., unharvested old growth stands, bole-only harvest stands, and whole-tree harvest + forest floor removal stands). The abundance of both bacterial and archaeal amoA were influenced by harvest method and soil depth; furthermore, archaeal amoA was 13x more abundant than bacterial amoA, across all soil depths. Sequencing and subsequent annotation of the ammonia oxidizing community revealed that the AOA were dominated by Crenarchaeota and AOB were dominated by Nitrosospira. Surface mineral soils (0-10 cm) amended with 1-octyne revealed that approximately 67-86% of total nitrification can be attributable to AOA activity. The highest rates of nitrification (total and 1-octyne resistant) occurred in the soils taken from the unharvested reference stands which were significantly greater than harvested stands. We can conclude that in this pine forest system, AOA dominates AOB in regards to amoA copy number and ammonia oxidizing activity. Not only is this study one of the first to investigate the ammonia-oxidizing population in southern pine forests, but also illustrates that timber harvest can lead to long-term alterations in nitrogen cycle processes.

  12. [Effects of biochar application on the abundance and structure of ammonia-oxidizer communities in coal-mining area.

    PubMed

    Liu, Yuan; Zhu, Ji Rong; Wu, Yu Chen; Shu, Liang Zuo

    2017-10-01

    As a new type of soil amendment, biochar can effectively improve soil fertility, structure and soil nitrogen transformation. We studied the effects of biochar application on soil properties, abundance and community structure of ammonia oxidizer in coal-mining area. The results showed that the biochar application significantly increased contents of soil NH4+-N, total nitrogen, available phosphorus and potassium. Compared with the control, no change in the abundance of ammonia-oxidizing archaea (AOA) was found under biochar treatment, but there was a significant increase in the abundance of ammonia-oxidizing bacteria (AOB). The analysis of T-RFLP profiles showed that biochar significantly increased the diversity indexes of AOA and AOB, and altered the community structure of both AOA and AOB. Improved soil nutrients as well as increased abundance and diversity of ammonia-oxidizing community to some extent indicated the potential of biochar application in reclamation of coal-mining area soil.

  13. Species, Abundance and Function of Ammonia-oxidizing Archaea in Inland Waters across China

    PubMed Central

    Zhou, Leiliu; Wang, Shanyun; Zou, Yuxuan; Xia, Chao; Zhu, Guibing

    2015-01-01

    Ammonia oxidation is the first step in nitrification and was thought to be performed solely by specialized bacteria. The discovery of ammonia-oxidizing archaea (AOA) changed this view. We examined the large scale and spatio-temporal occurrence, abundance and role of AOA throughout Chinese inland waters (n = 28). Molecular survey showed that AOA was ubiquitous in inland waters. The existence of AOA in extreme acidic, alkaline, hot, cold, eutrophic and oligotrophic environments expanded the tolerance limits of AOA, especially their known temperature tolerance to −25 °C, and substrate load to 42.04 mM. There were spatio-temporal divergences of AOA community structure in inland waters, and the diversity of AOA in inland water ecosystems was high with 34 observed species-level operational taxonomic units (OTUs; based on a 15% cutoff) distributed widely in group I.1b, I.1a, and I.1a-associated. The abundance of AOA was quite high (8.5 × 104 to 8.5 × 109 copies g−1), and AOA outnumbered ammonia-oxidizing bacteria (AOB) in the inland waters where little human activities were involved. On the whole AOB predominate the ammonia oxidation rate over AOA in inland water ecosystems, and AOA play an indispensable role in global nitrogen cycle considering that AOA occupy a broader habitat range than AOB, especially in extreme environments. PMID:26522086

  14. o-Naphthoquinone-Catalyzed Aerobic Oxidation of Amines to (Ket)imines: A Modular Catalyst Approach.

    PubMed

    Goriya, Yogesh; Kim, Hun Young; Oh, Kyungsoo

    2016-10-07

    A modular aerobic oxidation of amines to imines has been achieved using an ortho-naphthoquinone (o-NQ) catalyst. The cooperative catalyst system of o-NQ and Cu(OAc) 2 enabled the formation of homocoupled imines from benzylamines, while the presence of TFA helped the formation of cross-coupled imines in excellent yields. The current mild aerobic oxidation protocol could also be applied to the oxidation of secondary amines to imines or ketimines with the help of cocatalyst, Ag 2 CO 3 , with excellent yields.

  15. The reduction of nitric oxide by ammonia over polycrystalline platinum model catalysts in the presence of oxygen

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Katona, T.; Guczi, L.; Somorjai, G.A.

    1992-06-01

    The reaction system of nitric oxide, ammonia, and oxygen was studied using batch-mode measurements in partial pressure ranges of 65-1000 Pa (0.5-7.6 Torr) on polycrystalline Pt foils over the temperature range 423-598 K. Under these conditions the oxidation of nitric oxide was not detectable. The ammonia oxidation reaction, using dioxygen, occurred in the temperature range 423-493 K, producing nitrogen and water as the only products. The activation energy of the nitrogen formation was found to be 86 kJ/mol. Above this temperature range, flow-mode measurements showed the formation of both nitrous oxide and nitric oxide. The reaction rate between ammonia andmore » oxygen was greatly decreased (about a factor of 10) by nitric oxide, while the reaction rate between nitric oxide and ammonia was accelerated (about 10-fold) due to the presence of oxygen. Nitric oxide reduction by ammonia in the presence of oxygen occurred in the temperature range 423-598 K. The products of the reaction were nitrogen, oxygen nitrous oxide, and water. The Arrhenius plot of the reaction showed a break near 523 K. Below this temperature the activation energy of the reaction was 13 kJ/mol, and in the higher-temperature range it was 62 kJ/mol. At 473 K, the N[sub 2]/N[sub 2]O ratio was about 0.6 and O[sub 2] formation was also monitored. At 573 K, the N[sub 2]N[sub 2]O ratio was approximately 2 and oxygen was consumed in the course of the reaction as well.« less

  16. Multi-factorial drivers of ammonia oxidizer communities: evidence from a national soil survey.

    PubMed

    Yao, Huaiying; Campbell, Colin D; Chapman, Stephen J; Freitag, Thomas E; Nicol, Graeme W; Singh, Brajesh K

    2013-09-01

    The factors driving the abundance and community composition of soil microbial communities provide fundamental knowledge on the maintenance of biodiversity and the ecosystem services they underpin. Several studies have suggested that microbial communities are spatially organized, including functional groups and much of the observed variation is explained by geographical location or soil pH. Soil ammonia-oxidizing archaea (AOA) and bacteria (AOB) are excellent models for such study due to their functional, agronomic and environmental importance and their relative ease of characterization. To identify the dominant drivers of different ammonia oxidizers, we used samples (n = 713) from the National Soil Inventory of Scotland (NSIS). Our results indicate that 40-45% of the variance in community compositions can be explained by 71 environmental variables. Soil pH and substrate, which have been regarded as the two main drivers, only explained 13-16% of the total variance. We provide strong evidence of multi-factorial drivers (land use, soil type, climate and N deposition) of ammonia-oxidizing communities, all of which play a significant role in the creation of specific niches that are occupied by unique phylotypes. For example, one AOA phylotype was strongly linked to woodland/semi-natural grassland, rainfall and N deposition. Some soil typologies, namely regosols, have a novel AOA community composition indicating typology as one of the factors which defines this ecological niche. AOA abundance was high and strongly linked the rate of potential nitrification in the highly acidic soils supporting the argument that AOA are main ammonia oxidizers in acidic soils. However, for AOB, soil pH and substrate (ammonia) were the main drivers for abundance and community composition. These results highlight the importance of multiple drivers of microbial niche formation and their impact on microbial biogeography that have significant consequences for ecosystem functioning. © 2013 John

  17. Archaeal dominated ammonia-oxidizing communities in Icelandic grassland soils are moderately affected by long-term N fertilization and geothermal heating

    PubMed Central

    Daebeler, Anne; Abell, Guy C. J.; Bodelier, Paul L. E.; Bodrossy, Levente; Frampton, Dion M. F.; Hefting, Mariet M.; Laanbroek, Hendrikus J.

    2012-01-01

    The contribution of ammonia-oxidizing bacteria and archaea (AOB and AOA, respectively) to the net oxidation of ammonia varies greatly between terrestrial environments. To better understand, predict and possibly manage terrestrial nitrogen turnover, we need to develop a conceptual understanding of ammonia oxidation as a function of environmental conditions including the ecophysiology of associated organisms. We examined the discrete and combined effects of mineral nitrogen deposition and geothermal heating on ammonia-oxidizing communities by sampling soils from a long-term fertilization site along a temperature gradient in Icelandic grasslands. Microarray, clone library and quantitative PCR analyses of the ammonia monooxygenase subunit A (amoA) gene accompanied by physico-chemical measurements of the soil properties were conducted. In contrast to most other terrestrial environments, the ammonia-oxidizing communities consisted almost exclusively of archaea. Their bacterial counterparts proved to be undetectable by quantitative polymerase chain reaction suggesting AOB are only of minor relevance for ammonia oxidation in these soils. Our results show that fertilization and local, geothermal warming affected detectable ammonia-oxidizing communities, but not soil chemistry: only a subset of the detected AOA phylotypes was present in higher temperature soils and AOA abundance was increased in the fertilized soils, while soil physio-chemical properties remained unchanged. Differences in distribution and structure of AOA communities were best explained by soil pH and clay content irrespective of temperature or fertilizer treatment in these grassland soils, suggesting that these factors have a greater potential for ecological niche-differentiation of AOA in soil than temperature and N fertilization. PMID:23060870

  18. Archaeal dominated ammonia-oxidizing communities in Icelandic grassland soils are moderately affected by long-term N fertilization and geothermal heating.

    PubMed

    Daebeler, Anne; Abell, Guy C J; Bodelier, Paul L E; Bodrossy, Levente; Frampton, Dion M F; Hefting, Mariet M; Laanbroek, Hendrikus J

    2012-01-01

    The contribution of ammonia-oxidizing bacteria and archaea (AOB and AOA, respectively) to the net oxidation of ammonia varies greatly between terrestrial environments. To better understand, predict and possibly manage terrestrial nitrogen turnover, we need to develop a conceptual understanding of ammonia oxidation as a function of environmental conditions including the ecophysiology of associated organisms. We examined the discrete and combined effects of mineral nitrogen deposition and geothermal heating on ammonia-oxidizing communities by sampling soils from a long-term fertilization site along a temperature gradient in Icelandic grasslands. Microarray, clone library and quantitative PCR analyses of the ammonia monooxygenase subunit A (amoA) gene accompanied by physico-chemical measurements of the soil properties were conducted. In contrast to most other terrestrial environments, the ammonia-oxidizing communities consisted almost exclusively of archaea. Their bacterial counterparts proved to be undetectable by quantitative polymerase chain reaction suggesting AOB are only of minor relevance for ammonia oxidation in these soils. Our results show that fertilization and local, geothermal warming affected detectable ammonia-oxidizing communities, but not soil chemistry: only a subset of the detected AOA phylotypes was present in higher temperature soils and AOA abundance was increased in the fertilized soils, while soil physio-chemical properties remained unchanged. Differences in distribution and structure of AOA communities were best explained by soil pH and clay content irrespective of temperature or fertilizer treatment in these grassland soils, suggesting that these factors have a greater potential for ecological niche-differentiation of AOA in soil than temperature and N fertilization.

  19. Quantitative analyses of the abundance and composition of ammonia-oxidizing bacteria and ammonia-oxidizing archaea of a Chinese upland red soil under long-term fertilization practices.

    PubMed

    He, Ji-Zheng; Shen, Ju-Pei; Zhang, Li-Mei; Zhu, Yong-Guan; Zheng, Yuan-Ming; Xu, Ming-Gang; Di, Hongjie

    2007-09-01

    The abundance and composition of soil ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) were investigated by using quantitative real-time polymerase chain reaction, cloning and sequencing approaches based on amoA genes. The soil, classified as agri-udic ferrosols with pH (H(2)O) ranging from 3.7 to 6.0, was sampled in summer and winter from long-term field experimental plots which had received 16 years continuous fertilization treatments, including fallow (CK0), control without fertilizers (CK) and those with combinations of fertilizer nitrogen (N), phosphorus (P) and potassium (K): N, NP, NK, PK, NPK and NPK plus organic manure (OM). Population sizes of AOB and AOA changed greatly in response to the different fertilization treatments. The NPK + OM treatment had the highest copy numbers of AOB and AOA amoA genes among the treatments that received mineral fertilizers, whereas the lowest copy numbers were recorded in the N treatment. Ammonia-oxidizing archaea were more abundant than AOB in all the corresponding treatments, with AOA to AOB ratios ranging from 1.02 to 12.36. Significant positive correlations were observed among the population sizes of AOB and AOA, soil pH and potential nitrification rates, indicating that both AOB and AOA played an important role in ammonia oxidation in the soil. Phylogenetic analyses of the amoA gene fragments showed that all AOB sequences from different treatments were affiliated with Nitrosospira or Nitrosospira-like species and grouped into cluster 3, and little difference in AOB community composition was recorded among different treatments. All AOA sequences fell within cluster S (soil origin) and cluster M (marine and sediment origin). Cluster M dominated exclusively in the N, NP, NK and PK treatments, indicating a pronounced difference in the community composition of AOA in response to the long-term fertilization treatments. These findings could be fundamental to improve our understanding of the importance of

  20. Base-catalyzed efficient tandem [3 + 3] and [3 + 2 + 1] annulation-aerobic oxidative benzannulations.

    PubMed

    Diallo, Aboubacar; Zhao, Yu-Long; Wang, He; Li, Sha-Sha; Ren, Chuan-Qing; Liu, Qun

    2012-11-16

    An efficient synthesis of substituted benzenes via a base-catalyzed [3 + 3] aerobic oxidative aromatization of α,β-unsaturated carbonyl compounds with dimethyl glutaconate was reported. All the reactions were carried out under mild, metal-free conditions to afford the products in high to excellent yields with molecular oxygen as the sole oxidant and water as the sole byproduct. Furthermore, a more convenient tandem [3 + 2 + 1] aerobic oxidative aromatization reaction was developed through the in situ generation of the α,β-unsaturated carbonyl compounds from aldehydes and ketones.

  1. Abundance of ammonia oxidizing bacteria and archaea under long-term maize cropping systems.

    USDA-ARS?s Scientific Manuscript database

    Nitrification involves the oxidation of ammonium and is an important component of the overall N cycle. Nitrification occurs in two steps; first by oxidizing ammonium to nitrite, and then to nitrate. The first step is often the rate limiting step. Until recently ammonia-oxidizing bacteria were though...

  2. The Aerobic Oxidation of Bromide to Dibromine Catalyzed by Homogeneous Oxidation Catalysts and Initiated by Nitrate in Acetic Acid

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Partenheimer, Walt; Fulton, John L.; Sorensen, Christina M.

    A small amount of nitrate, ~0.002 molal, initiates the Co/Mn catalyzed aerobic oxidation of bromide compounds (HBr,NaBr,LiBr) to dibromine in acetic acid at room temperature. At temperatures 40oC or less , the reaction is autocatalytic. Co(II) and Mn(II) themselves and mixed with ionic bromide are known homogeneous oxidation catalysts. The reaction was discovered serendipitously when a Co/Br and Co/Mn/Br catalyst solution was prepared for the aerobic oxidation of methyaromatic compounds and the Co acetate contained a small amount of impurity i.e. nitrate. The reaction was characterized by IR, UV-VIS, MALDI and EXAFS spectroscopies and the coordination chemistry is described. Themore » reaction is inhibited by water and its rate changed by pH. The change in these variables, as well as others, are identical to those observed during homogeneous, aerobic oxidation of akylaromatics. A mechanism is proposed. Accidental addition of a small amount of nitrate compound into a Co/Mn/Br/acetic acid mixture in a large, commercial feedtank is potentially dangerous.« less

  3. Chemoselective organocatalytic aerobic oxidation of primary amines to secondary imines.

    PubMed

    Wendlandt, Alison E; Stahl, Shannon S

    2012-06-01

    Biomimetic aerobic oxidation of primary benzylic amines has been achieved by using a quinone catalyst. Excellent selectivity is observed for primary, unbranched benzylic amines relative to secondary/tertiary amines, branched benzylic amines, and aliphatic amines. The exquisite selectivity for benzylic amines enables oxidative self-sorting within dynamic mixtures of amines and imines to afford high yields of cross-coupled imine products.

  4. Emergence of Competitive Dominant Ammonia-Oxidizing Bacterial Populations in a Full-Scale Industrial Wastewater Treatment Plant

    PubMed Central

    Layton, Alice C.; Dionisi, Hebe; Kuo, H.-W.; Robinson, Kevin G.; Garrett, Victoria M.; Meyers, Arthur; Sayler, Gary S.

    2005-01-01

    Ammonia-oxidizing bacterial populations in an industrial wastewater treatment plant were investigated with amoA and 16S rRNA gene real-time PCR assays. Nitrosomonas nitrosa initially dominated, but over time RI-27-type ammonia oxidizers, also within the Nitrosomonas communis lineage, increased from below detection to codominance. This shift occurred even though nitrification remained constant. PMID:15691975

  5. Molecular Analysis of Ammonia-Oxidizing Bacteria of the β Subdivision of the Class Proteobacteria in Compost and Composted Materials

    PubMed Central

    Kowalchuk, George A.; Naoumenko, Zinaida S.; Derikx, Piet J. L.; Felske, Andreas; Stephen, John R.; Arkhipchenko, Irina A.

    1999-01-01

    Although the practice of composting animal wastes for use as biofertilizers has increased in recent years, little is known about the microorganisms responsible for the nitrogen transformations which occur in compost and during the composting process. Ammonia is the principle available nitrogenous compound in composting material, and the conversion of this compound to nitrite in the environment by chemolithotrophic ammonia-oxidizing bacteria is an essential step in nitrogen cycling. Therefore, the distribution of ammonia-oxidizing members of the β subdivision of the class Proteobacteria in a variety of composting materials was assessed by amplifying 16S ribosomal DNA (rDNA) and 16S rRNA by PCR and reverse transcriptase PCR (RT-PCR), respectively. The PCR and RT-PCR products were separated by denaturing gradient gel electrophoresis (DGGE) and were identified by hybridization with a hierarchical set of oligonucleotide probes designed to detect ammonia oxidizer-like sequence clusters in the genera Nitrosospira and Nitrosomonas. Ammonia oxidizer-like 16S rDNA was detected in almost all of the materials tested, including industrial and experimental composts, manure, and commercial biofertilizers. A comparison of the DGGE and hybridization results after specific PCR and RT-PCR suggested that not all of the different ammonia oxidizer groups detected in compost are equally active. amoA, the gene encoding the active-site-containing subunit of ammonia monooxygenase, was also targeted by PCR, and template concentrations were estimated by competitive PCR. Detection of ammonia-oxidizing bacteria in the composts tested suggested that such materials may not be biologically inert with respect to nitrification and that the fate of nitrogen during composting and compost storage may be affected by the presence of these organisms. PMID:9925559

  6. Bioinspired Aerobic Oxidation of Secondary Amines and Nitrogen Heterocycles with a Bifunctional Quinone Catalyst

    PubMed Central

    Wendlandt, Alison E.; Stahl, Shannon S.

    2014-01-01

    Copper amine oxidases are a family of enzymes with quinone cofactors that oxidize primary amines to aldehydes. The native mechanism proceeds via an iminoquinone intermediate that promotes high selectivity for reactions with primary amines, thereby constraining the scope of potential biomimetic synthetic applications. Here, we report a novel bioinspired quinone catalyst system, consisting of 1,10-phenanthroline-5,6-dione/ZnI2, that bypasses these constraints via an abiological pathway involving a hemiaminal intermediate. Efficient aerobic dehydrogenation of non-native secondary amine substrates, including pharmaceutically relevant nitrogen heterocycles, is demonstrated. The ZnI2 cocatalyst activates the quinone toward amine oxidation and provides a source of iodide, which plays an important redox-mediator role to promote aerobic catalytic turnover. These findings provide a valuable foundation for broader development of aerobic oxidation reactions employing quinone-based catalysts. PMID:24328193

  7. Bioinspired aerobic oxidation of secondary amines and nitrogen heterocycles with a bifunctional quinone catalyst.

    PubMed

    Wendlandt, Alison E; Stahl, Shannon S

    2014-01-08

    Copper amine oxidases are a family of enzymes with quinone cofactors that oxidize primary amines to aldehydes. The native mechanism proceeds via an iminoquinone intermediate that promotes high selectivity for reactions with primary amines, thereby constraining the scope of potential biomimetic synthetic applications. Here we report a novel bioinspired quinone catalyst system consisting of 1,10-phenanthroline-5,6-dione/ZnI2 that bypasses these constraints via an abiological pathway involving a hemiaminal intermediate. Efficient aerobic dehydrogenation of non-native secondary amine substrates, including pharmaceutically relevant nitrogen heterocycles, is demonstrated. The ZnI2 cocatalyst activates the quinone toward amine oxidation and provides a source of iodide, which plays an important redox-mediator role to promote aerobic catalytic turnover. These findings provide a valuable foundation for broader development of aerobic oxidation reactions employing quinone-based catalysts.

  8. Cu/Nitroxyl Catalyzed Aerobic Oxidation of Primary Amines into Nitriles at Room Temperature.

    PubMed

    Kim, Jinho; Stahl, Shannon S

    2013-07-05

    An efficient catalytic method has been developed for aerobic oxidation of primary amines to the corresponding nitriles. The reactions proceed at room temperature and employ a catalyst consisting of (4,4'- t Bu 2 bpy)CuI/ABNO (ABNO = 9-azabicyclo[3.3.1]nonan-3-one N -oxyl). The reactions exhibit excellent functional group compatibility and substrate scope, and are effective with benzylic, allylic and aliphatic amines. Preliminary mechanistic studies suggest that aerobic oxidation of the Cu catalyst is the turnover-limiting step of the reaction.

  9. RESULTS OF INITIAL AMMONIA OXIDATION TESTING

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Nash, C.; Fowley, M.

    This memo presents an experimental survey of aqueous phase chemical processes to remove aqueous ammonia from waste process streams. Ammonia is generated in both the current Hanford waste flowsheet and in future waste processing. Much ammonia will be generated in the Low Activity Waste (LAW) melters.i Testing with simulants in glass melters at Catholic University has demonstrated the significant ammonia production.ii The primary reaction there is the reducing action of sugar on nitrate in the melter cold cap. Ammonia has been found to be a problem in secondary waste stabilization. Ammonia vapors are noxious and destruction of ammonia could reducemore » hazards to waste treatment process personnel. It is easily evolved especially when ammonia-bearing solutions are adjusted to high pH.« less

  10. Biogeography of anaerobic ammonia-oxidizing (anammox) bacteria

    PubMed Central

    Sonthiphand, Puntipar; Hall, Michael W.; Neufeld, Josh D.

    2014-01-01

    Anaerobic ammonia-oxidizing (anammox) bacteria are able to oxidize ammonia and reduce nitrite to produce N2 gas. After being discovered in a wastewater treatment plant (WWTP), anammox bacteria were subsequently characterized in natural environments, including marine, estuary, freshwater, and terrestrial habitats. Although anammox bacteria play an important role in removing fixed N from both engineered and natural ecosystems, broad scale anammox bacterial distributions have not yet been summarized. The objectives of this study were to explore global distributions and diversity of anammox bacteria and to identify factors that influence their biogeography. Over 6000 anammox 16S rRNA gene sequences from the public database were analyzed in this current study. Data ordinations indicated that salinity was an important factor governing anammox bacterial distributions, with distinct populations inhabiting natural and engineered ecosystems. Gene phylogenies and rarefaction analysis demonstrated that freshwater environments and the marine water column harbored the highest and the lowest diversity of anammox bacteria, respectively. Co-occurrence network analysis indicated that Ca. Scalindua strongly connected with other Ca. Scalindua taxa, whereas Ca. Brocadia co-occurred with taxa from both known and unknown anammox genera. Our survey provides a better understanding of ecological factors affecting anammox bacterial distributions and provides a comprehensive baseline for understanding the relationships among anammox communities in global environments. PMID:25147546

  11. Response of Nitrosospira sp. strain AF-like ammonia oxidizers to changes in temperature, soil moisture content, and fertilizer concentration.

    PubMed

    Avrahami, Sharon; Bohannan, Brendan J M

    2007-02-01

    Very little is known regarding the ecology of Nitrosospira sp. strain AF-like bacteria, a unique group of ammonia oxidizers within the Betaproteobacteria. We studied the response of Nitrosospira sp. strain AF-like ammonia oxidizers to changing environmental conditions by applying molecular methods and physiological measurements to Californian grassland soil manipulated in the laboratory. This soil is naturally high in Nitrosospira sp. strain AF-like bacteria relative to the much-better-studied Nitrosospira multiformis-like ammonia-oxidizing bacteria. Increases in temperature, soil moisture, and fertilizer interacted to reduce the relative abundance of Nitrosospira sp. strain AF-like bacteria, although they remained numerically dominant. The overall abundance of ammonia-oxidizing bacteria increased with increasing soil moisture and decreased with increasing temperature. Potential nitrification activity was altered by interactions among temperature, soil moisture, and fertilizer, with activity tending to be higher when soil moisture and temperature were increased. The increase in potential nitrification activity with increased temperature was surprising, given that the overall abundance of ammonia-oxidizing bacteria decreased significantly under these conditions. This observation suggests that (i) Nitrosospira sp. strain AF-like bacteria may respond to increased temperature with an increase in activity, despite a decrease in abundance, or (ii) that potential nitrification activity in these soils may be due to organisms other than bacteria (e.g., archaeal ammonia oxidizers), at least under conditions of increased temperature.

  12. Response of Nitrosospira sp. Strain AF-Like Ammonia Oxidizers to Changes in Temperature, Soil Moisture Content, and Fertilizer Concentration▿

    PubMed Central

    Avrahami, Sharon; Bohannan, Brendan J. M.

    2007-01-01

    Very little is known regarding the ecology of Nitrosospira sp. strain AF-like bacteria, a unique group of ammonia oxidizers within the Betaproteobacteria. We studied the response of Nitrosospira sp. strain AF-like ammonia oxidizers to changing environmental conditions by applying molecular methods and physiological measurements to Californian grassland soil manipulated in the laboratory. This soil is naturally high in Nitrosospira sp. strain AF-like bacteria relative to the much-better-studied Nitrosospira multiformis-like ammonia-oxidizing bacteria. Increases in temperature, soil moisture, and fertilizer interacted to reduce the relative abundance of Nitrosospira sp. strain AF-like bacteria, although they remained numerically dominant. The overall abundance of ammonia-oxidizing bacteria increased with increasing soil moisture and decreased with increasing temperature. Potential nitrification activity was altered by interactions among temperature, soil moisture, and fertilizer, with activity tending to be higher when soil moisture and temperature were increased. The increase in potential nitrification activity with increased temperature was surprising, given that the overall abundance of ammonia-oxidizing bacteria decreased significantly under these conditions. This observation suggests that (i) Nitrosospira sp. strain AF-like bacteria may respond to increased temperature with an increase in activity, despite a decrease in abundance, or (ii) that potential nitrification activity in these soils may be due to organisms other than bacteria (e.g., archaeal ammonia oxidizers), at least under conditions of increased temperature. PMID:17158615

  13. Nitrate Reduction to Nitrite, Nitric Oxide and Ammonia by Gut Bacteria under Physiological Conditions

    PubMed Central

    Tiso, Mauro; Schechter, Alan N.

    2015-01-01

    The biological nitrogen cycle involves step-wise reduction of nitrogen oxides to ammonium salts and oxidation of ammonia back to nitrites and nitrates by plants and bacteria. Neither process has been thought to have relevance to mammalian physiology; however in recent years the salivary bacterial reduction of nitrate to nitrite has been recognized as an important metabolic conversion in humans. Several enteric bacteria have also shown the ability of catalytic reduction of nitrate to ammonia via nitrite during dissimilatory respiration; however, the importance of this pathway in bacterial species colonizing the human intestine has been little studied. We measured nitrite, nitric oxide (NO) and ammonia formation in cultures of Escherichia coli, Lactobacillus and Bifidobacterium species grown at different sodium nitrate concentrations and oxygen levels. We found that the presence of 5 mM nitrate provided a growth benefit and induced both nitrite and ammonia generation in E.coli and L.plantarum bacteria grown at oxygen concentrations compatible with the content in the gastrointestinal tract. Nitrite and ammonia accumulated in the growth medium when at least 2.5 mM nitrate was present. Time-course curves suggest that nitrate is first converted to nitrite and subsequently to ammonia. Strains of L.rhamnosus, L.acidophilus and B.longum infantis grown with nitrate produced minor changes in nitrite or ammonia levels in the cultures. However, when supplied with exogenous nitrite, NO gas was readily produced independently of added nitrate. Bacterial production of lactic acid causes medium acidification that in turn generates NO by non-enzymatic nitrite reduction. In contrast, nitrite was converted to NO by E.coli cultures even at neutral pH. We suggest that the bacterial nitrate reduction to ammonia, as well as the related NO formation in the gut, could be an important aspect of the overall mammalian nitrate/nitrite/NO metabolism and is yet another way in which the microbiome

  14. Ammonium supply rate influences archaeal and bacterial ammonia oxidizers in a wetland soil vertical profile.

    PubMed

    Höfferle, Špela; Nicol, Graeme W; Pal, Levin; Hacin, Janez; Prosser, James I; Mandić-Mulec, Ines

    2010-11-01

    Oxidation of ammonia, the first step in nitrification, is carried out in soil by bacterial and archaeal ammonia oxidizers and recent studies suggest possible selection for the latter in low-ammonium environments. In this study, we investigated the selection of ammonia-oxidizing archaea and bacteria in wetland soil vertical profiles at two sites differing in terms of the ammonium supply rate, but not significantly in terms of the groundwater level. One site received ammonium through decomposition of organic matter, while the second, polluted site received a greater supply, through constant leakage of an underground septic tank. Soil nitrification potential was significantly greater at the polluted site. Quantification of amoA genes demonstrated greater abundance of bacterial than archaeal amoA genes throughout the soil profile at the polluted site, whereas bacterial amoA genes at the unpolluted site were below the detection limit. At both sites, archaeal, but not the bacterial community structure was clearly stratified with depth, with regard to the soil redox potential imposed by groundwater level. However, depth-related changes in the archaeal community structure may also be associated with physiological functions other than ammonia oxidation. © 2010 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  15. Effects of ammonia exposure on apoptosis, oxidative stress and immune response in pufferfish (Takifugu obscurus).

    PubMed

    Cheng, Chang-Hong; Yang, Fang-Fang; Ling, Ren-Zhi; Liao, Shao-An; Miao, Yu-Tao; Ye, Chao-Xia; Wang, An-Li

    2015-07-01

    Ammonia is one of major environmental pollutants in the freshwater aquatic system that affects the survival and growth of organisms. In the present study, we investigated the effects of ammonia exposure on apoptosis, oxidative stress and immune response in pufferfish (Takifugu obscurus). Fish were exposed to various concentrations of ammonia (0, 1.43, 3.57, 7.14mM) for 72h. The date showed that ammonia exposure could induce intracellular reactive oxygen species (ROS), interrupt intracellular Ca(2+) (cf-Ca(2+)) homeostasis, and subsequently lead to DNA damage and cell apoptosis. To test the apoptotic pathway, the expression patterns of some key apoptotic related genes including P53, Bax Bcl2, Caspase 9, Caspase 8 and Caspase 3 in the liver were examined. The results showed that ammonia stress could change these genes transcription, associated with increasing of cell apoptosis, suggesting that the P53-Bax-Bcl2 pathway and caspase-dependent apoptotic pathway could be involved in cell apoptosis induced by ammonia stress. In addition, ammonia stress could induced up-regulation of inflammatory cytokines (BAFF, TNF-α, IL-6 and IL-12) transcription, indicating that innate immune system play important roles in ammonia-induced toxicity in fish. Furthermore, the gene expressions of antioxidant enzymes (Mn-SOD, CAT, GPx, and GR) and heat shock proteins (HSP90 and HSP70) in the liver were induced by ammonia stress, suggesting that antioxidant system and heat shock proteins tried to protect cells from oxidative stress and apoptosis induced by ammonia stress. Our results will be helpful to understand the mechanism of aquatic toxicology induced by ammonia in fish. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Cu/Nitroxyl Catalyzed Aerobic Oxidation of Primary Amines into Nitriles at Room Temperature

    PubMed Central

    Kim, Jinho; Stahl, Shannon S.

    2013-01-01

    An efficient catalytic method has been developed for aerobic oxidation of primary amines to the corresponding nitriles. The reactions proceed at room temperature and employ a catalyst consisting of (4,4′-tBu2bpy)CuI/ABNO (ABNO = 9-azabicyclo[3.3.1]nonan-3-one N-oxyl). The reactions exhibit excellent functional group compatibility and substrate scope, and are effective with benzylic, allylic and aliphatic amines. Preliminary mechanistic studies suggest that aerobic oxidation of the Cu catalyst is the turnover-limiting step of the reaction. PMID:24015373

  17. Acidification Enhances Hybrid N2O Production Associated with Aquatic Ammonia-Oxidizing Microorganisms

    PubMed Central

    Frame, Caitlin H.; Lau, Evan; Nolan, E. Joseph; Goepfert, Tyler J.; Lehmann, Moritz F.

    2017-01-01

    Ammonia-oxidizing microorganisms are an important source of the greenhouse gas nitrous oxide (N2O) in aquatic environments. Identifying the impact of pH on N2O production by ammonia oxidizers is key to understanding how aquatic greenhouse gas fluxes will respond to naturally occurring pH changes, as well as acidification driven by anthropogenic CO2. We assessed N2O production rates and formation mechanisms by communities of ammonia-oxidizing bacteria (AOB) and archaea (AOA) in a lake and a marine environment, using incubation-based nitrogen (N) stable isotope tracer methods with 15N-labeled ammonium (15NH4+) and nitrite (15NO2−), and also measurements of the natural abundance N and O isotopic composition of dissolved N2O. N2O production during incubations of water from the shallow hypolimnion of Lake Lugano (Switzerland) was significantly higher when the pH was reduced from 7.54 (untreated pH) to 7.20 (reduced pH), while ammonia oxidation rates were similar between treatments. In all incubations, added NH4+ was the source of most of the N incorporated into N2O, suggesting that the main N2O production pathway involved hydroxylamine (NH2OH) and/or NO2− produced by ammonia oxidation during the incubation period. A small but significant amount of N derived from exogenous/added 15NO2− was also incorporated into N2O, but only during the reduced-pH incubations. Mass spectra of this N2O revealed that NH4+ and 15NO2− each contributed N equally to N2O by a “hybrid-N2O” mechanism consistent with a reaction between NH2OH and NO2−, or compounds derived from these two molecules. Nitrifier denitrification was not an important source of N2O. Isotopomeric N2O analyses in Lake Lugano were consistent with incubation results, as 15N enrichment of the internal N vs. external N atoms produced site preferences (25.0–34.4‰) consistent with NH2OH-dependent hybrid-N2O production. Hybrid-N2O formation was also observed during incubations of seawater from coastal Namibia

  18. Platinum Electrodeposition at Unsupported Electrochemically Reduced Nanographene Oxide for Enhanced Ammonia Oxidation

    PubMed Central

    2015-01-01

    The electrochemical reduction of highly oxidized unsupported graphene oxide nanosheets and its platinum electrodeposition was done by the rotating disk slurry electrode technique. Avoiding the use of a solid electrode, graphene oxide was electrochemically reduced in a slurry solution with a scalable process without the use of a reducing agent. Graphene oxide nanosheets were synthesized from carbon platelet nanofibers to obtain highly hydrophilic layers of less than 250 nm in width. The graphene oxide and electrochemically reduced graphene oxide/Pt (erGOx/Pt) hybrid materials were characterized through different spectroscopy and microscopy techniques. Pt nanoparticles with 100 facets, clusters, and atoms at erGOx were identified by high resolution transmission electron microscopy (HRTEM). Cyclic voltammetry was used to characterize the electrocatalytic activity of the highly dispersed erGOx/Pt hybrid material toward the oxidation of ammonia, which showed a 5-fold current density increase when compared with commercially available Vulcan/Pt 20%. This is in agreement with having Pt (100) facets present in the HRTEM images of the erGOx/Pt material. PMID:24417177

  19. Composition of ammonia-oxidizing archaea and their contribution to nitrification in a high-temperature hot spring

    NASA Astrophysics Data System (ADS)

    Chen, S.; Peng, X.-T.; Xu, H.-C.; Ta, K.-W.

    2015-10-01

    The oxidation of ammonia by microbes and associated organisms has been shown to occur in diverse natural environments. However, the contribution of ammonia-oxidizing archaea to nitrification in high-temperature environments remains unclear. Here, we studied in situ ammonia oxidation rates and the abundance of ammonia-oxidizing archaea (AOA) in surface and bottom sediments at 77 °C in the Gongxiaoshe hot spring, Tengchong, Yunnan, China. The in situ ammonia oxidation rates measured by the 15N-NO3- pool dilution technique in the surface sinter and bottom sediments were 4.8 and 5.3 nmol N g-1 h-1, respectively. Relative abundances of Crenarchaea in both samples were determined by fluorescence in situ hybridization (FISH). Phylogenetic analysis of 16S rRNA genes showed high sequence similarity to thermophilic "Candidatus Nitrosocaldus yellowstonii", which represented the most abundant operation taxonomic units (OTU) in both sediments. Furthermore, bacterial amoA was not detected in this study. Quantitative PCR (qPCR) indicated that AOA and 16S rRNA genes were present in the range of 2.75 to 9.80 × 105 and 0.128 to 1.96 × 108 gene copies g-1 sediment. The cell-specific nitrification rates were estimated to be in the range of 0.41 to 0.79 fmol N archaeal cell-1 h-1, which is consistent with earlier estimates in estuary environments. This study demonstrated that AOA were widely involved in nitrification in this hot spring. It further indicated the importance of archaea rather than bacteria in driving the nitrogen cycle in terrestrial geothermal environments.

  20. Studies of Heterogenous Palladium and Related Catalysts for Aerobic Oxidation of Primary Alcohols

    NASA Astrophysics Data System (ADS)

    Ahmed, Maaz S.

    Development of aerobic oxidation methods is of critical importance for the advancement of green chemistry, where the only byproduct produced is water. Recent work by our lab has produced an efficient Pd based heterogenous catalyst capable of preforming the aerobic oxidation of a wide spectrum of alcohols to either carboxylic acid or methyl ester. The well-defined catalyst PdBi 0.35Te0.23/C (PBT/C) catalyst has been shown to can perform the aerobic oxidation of alcohols to carboxylic acids in basic conditions. Additionally, we explored this catalyst for a wide range of alcohols and probed the nature of the selectivity of PBT/C for methyl esterification over other side products. Finally, means by which the catalyst operates with respect to oxidation states of the three components, Pd, Bi, and Te, was probed. Carboxylic acids are an important functional group due to their prevalence in various pharmaceutically active agents, agrochemicals, and commodity scale chemicals. The well-defined catalyst PBT/C catalyst was discovered to be effective for the oxidation of a wide spectrum of alcohols to carboxylic acid. The demonstrated substrate scope and functional group tolerance are the widest reported for an aerobic heterogeneous catalyst. Additionally, the catalyst has been implemented in a packed bed reactor with quantitative yield of benzoic acid maintained throughout a two-day run. Biomass derived 5-(hydroxymethyl)furfural (HMF) is also oxidized to 2,5-furandicarboxylic acid (FDCA) in high yield. Exploration of PBT/C for the oxidative methyl esterification was found to exhibit exquisite selectivity for the initial oxidation of primary alcohol instead of methanol, which is the bulk solvent. We explored this selectivity and conclude that it results from various substrate-surface interactions, which are not attainable by methanol. The primary alcohol can outcompete the methanol for binding on the catalyst surface through various interactions between the side chain of the

  1. Treatment of ammonia by catalytic wet oxidation process over platinum-rhodium bimetallic catalyst in a trickle-bed reactor: effect of pH.

    PubMed

    Hung, Chang-Mao; Lin, Wei-Bang; Ho, Ching-Lin; Shen, Yun-Hwei; Hsia, Shao-Yi

    2010-08-01

    This work adopted aqueous solutions of ammonia for use in catalytic liquid-phase reduction in a trickle-bed reactor with a platinum-rhodium bimetallic catalyst, prepared by the co-precipitation of chloroplatinic acid (H2PtCl6) and rhodium nitrate [Rh(NO3)3]. The experimental results demonstrated that a minimal amount of ammonia was removed from the solution by wet oxidation in the absence of any catalyst, while approximately 97.0% of the ammonia was removed by wet oxidation over the platinum-rhodium bimetallic catalyst at 230 degrees C with an oxygen partial pressure of 2.0 MPa. The oxidation of ammonia has been studied as a function of pH, and the main reaction products were determined. A synergistic effect is manifest in the platinum-rhodium bimetallic structure, in which the material has the greatest capacity to reduce ammonia. The reaction pathway linked the oxidizing ammonia to nitric oxide, nitrogen, and water.

  2. Vertical Segregation and Phylogenetic Characterization of Ammonia-Oxidizing Bacteria and Archaea in the Sediment of a Freshwater Aquaculture Pond

    PubMed Central

    Lu, Shimin; Liu, Xingguo; Ma, Zhuojun; Liu, Qigen; Wu, Zongfan; Zeng, Xianlei; Shi, Xu; Gu, Zhaojun

    2016-01-01

    Pond aquaculture is the major freshwater aquaculture method in China. Ammonia-oxidizing communities inhabiting pond sediments play an important role in controlling culture water quality. However, the distribution and activities of ammonia-oxidizing microbial communities along sediment profiles are poorly understood in this specific environment. Vertical variations in the abundance, transcription, potential ammonia oxidizing rate, and community composition of ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) in sediment samples (0–50 cm depth) collected from a freshwater aquaculture pond were investigated. The concentrations of the AOA amoA gene were higher than those of the AOB by an order of magnitude, which suggested that AOA, as opposed to AOB, were the numerically predominant ammonia-oxidizing organisms in the surface sediment. This could be attributed to the fact that AOA are more resistant to low levels of dissolved oxygen. However, the concentrations of the AOB amoA mRNA were higher than those of the AOA by 2.5- to 39.9-fold in surface sediments (0–10 cm depth), which suggests that the oxidation of ammonia was mainly performed by AOB in the surface sediments, and by AOA in the deeper sediments, where only AOA could be detected. Clone libraries of AOA and AOB amoA sequences indicated that the diversity of AOA and AOB decreased with increasing depth. The AOB community consisted of two groups: the Nitrosospira and Nitrosomonas clusters, and Nitrosomonas were predominant in the freshwater pond sediment. All AOA amoA gene sequences in the 0–2 cm deep sediment were grouped into the Nitrososphaera cluster, while other AOA sequences in deeper sediments (10–15 and 20–25 cm depths) were grouped into the Nitrosopumilus cluster. PMID:26834709

  3. Potential nitrous oxide yield of AOA vs. AOB and utilization of carbon and nitrogen in the ammonia oxidizing process in the Pearl River Estuary

    NASA Astrophysics Data System (ADS)

    Ma, L.; Dai, M.; Tan, S.; Xia, X.; Liu, H.

    2016-12-01

    Nitrous oxide (N2O), a greenhouse gas, is a by-product during ammonia oxidation process, the production of which is often stimulated under low dissolved oxygen (DO) in the estuarine environment. The potential yield of N2O has been considered to be driven by ammonia-oxidizing bacteria (AOB) of Betaproteobacteria & Gammaproteobacteria and/or ammonia-oxidizing archaea (AOA) of Thaumarchaeota. In order to examine the relative importance of AOA and AOB in producing N2O and in modulating the potential N2O yield, arch-amoA, beta-amoA, gamma-amoA encoding for the alpha subunit of the ammonia monooxygenase (AMO) are used as biomarkers to identify the distributions and bioactivities of AOA and AOB in the Pearl River Estuary (PRE). Size fractionation experiments were conducted to distinguish AOA and AOB on particles in different size-fractions of > 3 μm, 0.45-3 μm, and 0.22-0.45 μm. Pure culture of N. maritimusSCM1 was studied as a model organism to identify the organic carbon production during ammonia oxidation by SCM1 strains. Our results show that AOA distributes largely in the free-living state and could adapt to very limited ammonia substrate and low saturation of DO; AOB mainly distributes at the particle-attached state under relative richer ammonia and high DO conditions; however, the RNA/DNA ratio of AOB was higher than that of AOA under the same conditions suggesting AOB is relatively more actively expressed. In the upper reach of PRE, the dominant microorganism in the water column was AOB and the in situ N2O/NH3 therein ranged 0.73-3.74 ‰. In the lower PRE, AOA was dominated, and the in situ N2O/NH3 was of 1.17- 7.32‰. At selected sites, we estimated isotope effect (e) of AOA (eDIC/bulk) as -23.94‰ and AOB (eDIC/bulk) as -56.6‰ to -44.8‰, which is consistent with the studies of pure cultures. The coefficient of C sequestration "k", defined as (C biomass / DIC in situ) / (N biomass / ammonia in situ) to differ the utilization of carbon and nitrogen, of

  4. Thaumarchaeal amoA and nirK Gene Abundance Patterns Reveal Spatiotemporal Dynamics of Ammonia-oxidizing Archaeal Populations in Monterey Bay, CA

    NASA Astrophysics Data System (ADS)

    Tolar, B. B.; Reji, L.; Smith, J. M.; Chavez, F.; Francis, C.

    2016-12-01

    Thaumarchaeaota are among the most abundant microorganisms on the planet, and are significant players in the global nitrogen cycle. All cultivated members of the phylum are capable of performing the first and rate-limiting step of nitrification - the aerobic oxidation of ammonia to nitrite. In marine environments, ammonia-oxidizing archaea (AOA) have been found to greatly outnumber their bacterial counterparts. However, much about their ecology remains largely unknown. Monterey Bay, a non-estuarine embayment on the central California coast, is an ideal site for studying the dynamics of natural thaumarchaeal assemblages, given the highly dynamic nature of the Bay waters with seasonal upwelling episodes and the associated steep gradients in environmental variables. In the present study, we examined thaumarchaeal population dynamics in the upper Monterey Bay water column (0-500 m) using multiple molecular markers. Following high-resolution spatiotemporal sampling (i.e., up to 10 depths sampled monthly over a period of 2 years) at two stations in the Bay, we quantified thaumarchaeal functional genes - the ammonia monooxygenase (amoA) gene and its `shallow' and `deep' marine ecotypes, and variants of the marine nitrite reductase (nirK) gene. The abundances of both genes were regressed against environmental variables to gain insights into factors shaping their spatiotemporal dynamics in the Bay. Gene abundances at both stations varied with depth and season, with winter months generally having several orders of magnitude greater abundances. Statistical analyses point to differential controls on the gene abundances, with depth and temperature potentially being the major environmental determinants of thaumarchaeal population size. Our results also highlight the importance of employing multiple marker genes to gain a more highly resolved picture of thaumarchaeal population dynamics in complex environmental systems such as the coastal ocean.

  5. Finely controlled multimetallic nanocluster catalysts for solvent-free aerobic oxidation of hydrocarbons

    PubMed Central

    Takahashi, Masaki; Koizumi, Hiromu; Chun, Wang-Jae; Kori, Makoto; Imaoka, Takane; Yamamoto, Kimihisa

    2017-01-01

    The catalytic activity of alloy nanoparticles depends on the particle size and composition ratio of different metals. Alloy nanoparticles composed of Pd, Pt, and Au are widely used as catalysts for oxidation reactions. The catalytic activities of Pt and Au nanoparticles in oxidation reactions are known to increase as the particle size decreases and to increase on the metal-metal interface of alloy nanoparticles. Therefore, multimetallic nanoclusters (MNCs) around 1 nm in diameter have potential as catalysts for oxidation reactions. However, there have been few reports describing the preparation of uniform alloy nanoclusters. We report the synthesis of finely controlled MNCs (around 1 nm) using a macromolecular template with coordination sites arranged in a gradient of basicity. We reveal that Cu-Pt-Au MNCs supported on graphitized mesoporous carbon show catalytic activity that is 24 times greater than that of a commercially available Pt catalyst for aerobic oxidation of hydrocarbons. In addition, solvent-free aerobic oxidation of hydrocarbons to ketones at room temperature, using small amounts of a radical initiator, was achieved as a heterogeneous catalytic reaction for the first time. PMID:28782020

  6. Ammonia Movement in the Small Intestine: Preferential Transport by the Ileum *

    PubMed Central

    Mossberg, Sanford M.; Ross, George

    1967-01-01

    Isolated, surviving sacs of everted small intestine were used to characterize ammonia transport in the golden hamster. Jejunal and ileal sacs incubated aerobically in ammonia-free test solution liberated the same quantity of ammonia as did sacs that were filled and immediately emptied of their contents, indicating no significant evolution of metabolic ammonia. Under aerobic conditions, ileal sacs transferred a solution of high ammonia content from the mucosal surface to the serosal surface against a concentration gradient. This transport was not glucose dependent and exhibited first-order Michaelis-Menten kinetics. Inhibition of absorption occurred with anaerobiosis, 2,4-dinitrophenol, and sodium cyanide. In jejunal segments ammonia was not transported against an adverse chemical gradient. Ileal ammonia absorption was accompanied by bicarbonate secretion and acidification of the serosal solution. Both bicarbonate movement and pH gradients were abolished by inhibitors of ammonia transport. In the jejunum, the absence of ammonia movement occurred in association with minimal bicarbonate secretion and no appreciable change in serosal pH. Despite the creation of hydrogen ion gradients tending to augment or to retard ammonia absorption by nonionic diffusion, ammonia movement was unaffected, i.e., relative acidification of serosal contents did not augment ammonia absorption, and relative alkalinization of serosal fluid caused no inhibition of ammonia transport. In the absence of bicarbonate ion, ammonia transport did not occur. The significance of these findings is discussed with consideration of both ionic and nonionic mechanisms of ammonia movement. It is suggested that ammonia is absorbed in the ileum by active ionic transport. PMID:6021202

  7. Ammonia-oxidizing bacteria and archaea within biofilters of a commercial recirculating marine aquaculture system.

    PubMed

    Huang, Zhitao; Jiang, Yuli; Song, Xiefa; Hallerman, Eric; Peng, Lei; Dong, Dengpan; Ma, Teng; Zhai, Jieming; Li, Wensheng

    2018-02-10

    While biofilters are widely used to metabolize ammonia and other wastes in marine recirculating aquaculture systems, the ammonia-oxidizing bacterial and archaeal communities have not been characterized across a diversity of production systems. Using a metagenomics approach, we characterized the ammonia-oxidizing microbiological community of biofilters in a commercial recirculating marine aquaculture system producing hybrid grouper (Epinephelus lanceolatus × E. fuscoguttatus). Cloning and sequencing of the amoA gene showed that nitrifying bacteria included Nitrosomonas europea, N. stercoris, N. cryotolerans, N. eutropha, N. estuarii, eight strains of N. marina, and 15 strains not associated with described species. Nitrifying archaea included eight strains of Nitrosopumilus maritimus, N. koreensis, N. piranensis, N. adriaticus, undescribed congeners, and other undescribed archaea. The species composition of the bacterial and especially the archaeal communities was beyond that yet reported for aquaculture biofilters. While ammonia flux through the respective communities has yet to be estimated, the diverse environmental adaptations of the bacterial and archaeal communities suggest resilience of function under a range of environmental conditions.

  8. High resolution and comprehensive techniques to analyze aerobic methane oxidation in mesocosm experiments

    NASA Astrophysics Data System (ADS)

    Chan, E. W.; Kessler, J. D.; Redmond, M. C.; Shiller, A. M.; Arrington, E. C.; Valentine, D. L.; Colombo, F.

    2015-12-01

    Many studies of microbially mediated aerobic methane oxidation in oceanic environments have examined the many different factors that control the rates of oxidation. However, there is debate on how quickly methane is oxidized once a microbial population is established and what factor(s) are limiting in these types of environments. These factors include the availability of CH4, O2, trace metals, nutrients, and the density of cell population. Limits to these factors can also control the temporal aspects of a methane oxidation event. In order to look at this process in its entirety and with higher temporal resolution, a mesocosm incubation system was developed with a Dissolved Gas Analyzer System (DGAS) coupled with a set of analytical tools to monitor aerobic methane oxidation in real time. With the addition of newer laser spectroscopy techniques (cavity ringdown spectroscopy), stable isotope fractionation caused by microbial processes can also be examined on a real time and automated basis. Cell counting, trace metal, nutrient, and DNA community analyses have also been carried out in conjunction with these mesocosm samples to provide a clear understanding of the biology in methane oxidation dynamics. This poster will detail the techniques involved to provide insights into the chemical and isotopic kinetics controlling aerobic methane oxidation. Proof of concept applications will be presented from seep sites in the Hudson Canyon and the Sleeping Dragon seep field, Mississippi Canyon 118 (MC 118). This system was used to conduct mesocosm experiments to examine methane consumption, O2 consumption, nutrient consumption, and biomass production.

  9. Responses of Ammonia-Oxidizing Bacterial and Archaeal Populations to Organic Nitrogen Amendments in Low-Nutrient Groundwater ▿

    PubMed Central

    Reed, David W.; Smith, Jason M.; Francis, Christopher A.; Fujita, Yoshiko

    2010-01-01

    To evaluate the potential for organic nitrogen addition to stimulate the in situ growth of ammonia oxidizers during a field scale bioremediation trial, samples collected from the Eastern Snake River Plain Aquifer in Idaho before, during, and after the addition of molasses and urea were subjected to PCR analysis of ammonia monooxygenase subunit A (amoA) genes. Ammonia-oxidizing bacteria (AOB) and archaea (AOA) were present in all of the samples tested, with AOA amoA genes outnumbering AOB amoA genes in all of the samples. Following urea addition, nitrate levels rose and bacterial amoA copy numbers increased dramatically, suggesting that urea hydrolysis stimulated nitrification. Bacterial amoA diversity was limited to two Nitrosomonas phylotypes, whereas archaeal amoA analyses revealed 20 distinct operational taxonomic units, including several that were markedly different from all previously reported sequences. Results from this study demonstrate the likelihood of stimulating ammonia-oxidizing communities during field scale manipulation of groundwater conditions to promote urea hydrolysis. PMID:20190081

  10. Complete Genome Sequence of Nitrosomonas cryotolerans ATCC 49181, a Phylogenetically Distinct Ammonia-Oxidizing Bacterium Isolated from Arctic Waters

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Rice, Marlen C.; Norton, Jeanette M.; Stein, Lisa Y.

    ABSTRACT Nitrosomonas cryotoleransATCC 49181 is a cold-tolerant marine ammonia-oxidizing bacterium isolated from seawater collected in the Gulf of Alaska. The high-quality complete genome contains a 2.87-Mbp chromosome and a 56.6-kbp plasmid. Chemolithoautotrophic modules encoding ammonia oxidation and CO 2 fixation were identified.

  11. Complete Genome Sequence of Nitrosomonas cryotolerans ATCC 49181, a Phylogenetically Distinct Ammonia-Oxidizing Bacterium Isolated from Arctic Waters

    DOE PAGES

    Rice, Marlen C.; Norton, Jeanette M.; Stein, Lisa Y.; ...

    2017-03-16

    ABSTRACT Nitrosomonas cryotoleransATCC 49181 is a cold-tolerant marine ammonia-oxidizing bacterium isolated from seawater collected in the Gulf of Alaska. The high-quality complete genome contains a 2.87-Mbp chromosome and a 56.6-kbp plasmid. Chemolithoautotrophic modules encoding ammonia oxidation and CO 2 fixation were identified.

  12. Ammonia-Oxidizing Bacteria in Biofilters Removing Trihalomethanes Are Related to Nitrosomonas oligotropha

    EPA Science Inventory

    Nitrifying biofilters degrading the four regulated trihalomethanes (THMs) trichloromethane (TCM), bromodichloromethane (BDCM), dibromochloromethane (DBCM), and tribromomethane (TBM) -were analyzed for the presence and activity of ammonia-oxidizing bacteria (AOB). Biofilter perfor...

  13. Effects of Calcination Temperature and Acid-Base Properties on Mixed Potential Ammonia Sensors Modified by Metal Oxides

    PubMed Central

    Satsuma, Atsushi; Katagiri, Makoto; Kakimoto, Shiro; Sugaya, Satoshi; Shimizu, Kenichi

    2011-01-01

    Mixed potential sensors were fabriated using yttria-stabilized zirconia (YSZ) as a solid electrolyte and a mixture of Au and various metal oxides as a sensing electrode. The effects of calcination temperature ranging from 600 to 1,000 °C and acid-base properties of the metal oxides on the sensing properties were examined. The selective sensing of ammonia was achieved by modification of the sensing electrode using MoO3, Bi2O3 and V2O5, while the use of WO3, Nb2O5 and MgO was not effective. The melting points of the former group were below 820 °C, while those of the latter group were higher than 1,000 °C. Among the former group, the selective sensing of ammonia was strongly dependent on the calcination temperature, which was optimum around melting point of the corresponding metal oxides. The good spreading of the metal oxides on the electrode is suggested to be one of the important factors. In the former group, the relative response of ammonia to propene was in the order of MoO3 > Bi2O3 > V2O5, which agreed well with the acidity of the metal oxides. The importance of the acidic properties of metal oxides for ammonia sensing was clarified. PMID:22319402

  14. Effects of calcination temperature and acid-base properties on mixed potential ammonia sensors modified by metal oxides.

    PubMed

    Satsuma, Atsushi; Katagiri, Makoto; Kakimoto, Shiro; Sugaya, Satoshi; Shimizu, Kenichi

    2011-01-01

    Mixed potential sensors were fabriated using yttria-stabilized zirconia (YSZ) as a solid electrolyte and a mixture of Au and various metal oxides as a sensing electrode. The effects of calcination temperature ranging from 600 to 1,000 °C and acid-base properties of the metal oxides on the sensing properties were examined. The selective sensing of ammonia was achieved by modification of the sensing electrode using MoO(3), Bi(2)O(3) and V(2)O(5), while the use of WO(3,) Nb(2)O(5) and MgO was not effective. The melting points of the former group were below 820 °C, while those of the latter group were higher than 1,000 °C. Among the former group, the selective sensing of ammonia was strongly dependent on the calcination temperature, which was optimum around melting point of the corresponding metal oxides. The good spreading of the metal oxides on the electrode is suggested to be one of the important factors. In the former group, the relative response of ammonia to propene was in the order of MoO(3) > Bi(2)O(3) > V(2)O(5), which agreed well with the acidity of the metal oxides. The importance of the acidic properties of metal oxides for ammonia sensing was clarified.

  15. Nitrogen losses, uptake and abundance of ammonia oxidizers in soil under mineral and organo-mineral fertilization regimes.

    PubMed

    Florio, Alessandro; Felici, Barbara; Migliore, Melania; Dell'Abate, Maria Teresa; Benedetti, Anna

    2016-05-01

    A laboratory incubation experiment and greenhouse studies investigated the impact of organo-mineral (OM) fertilization as an alternative practice to conventional mineral (M) fertilization on nitrogen (N) uptake and losses in perennial ryegrass (Lolium perenne) as well as on soil microbial biomass and ammonia oxidizers. While no significant difference in plant productivity and ammonia emissions between treatments could be detected, an increase in soil total N content and an average 17.9% decrease in nitrates leached were observed in OM fertilization compared with M fertilization. The microbial community responded differentially to treatments, suggesting that the organic matter fraction of the OM fertilizer might have influenced N immobilization in the microbial biomass in the short-medium term. Furthermore, nitrate contents in fertilized soils were significantly related to bacterial but not archaeal amoA gene copies, whereas in non-fertilized soils a significant relationship between soil nitrates and archaeal but not bacterial amoA copies was found. The application of OM fertilizer to soil maintained sufficient productivity and in turn increased N use efficiency and noticeably reduced N losses. Furthermore, in this experiment, ammonia-oxidizing bacteria drove nitrification when an N source was added to the soil, whereas ammonia-oxidizing archaea were responsible for ammonia oxidation in non-fertilized soil. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

  16. Comparison of PCR primer-based strategies for characterization of ammonia oxidizer communities in environmental samples.

    PubMed

    Mahmood, Shahid; Freitag, Thomas E; Prosser, James I

    2006-06-01

    PCR-based techniques are commonly used to characterize microbial communities, but are subject to bias that is difficult to assess. This study aimed to evaluate bias of several PCR primer-based strategies used to study diversity of autotrophic ammonia oxidizers. 16S rRNA genes from soil- or sediment-DNA were amplified using primers considered either selective or specific for betaproteobacterial ammonia oxidizers. Five approaches were assessed: (a) amplification with primers betaAMO143f-betaAMO1315r; (b) amplification with primers CTO189f-CTO654r; (c) nested amplification with betaAMO143f-betaAMO1315r followed by CTO189f-CTO654r primers; (d) nested amplification with betaAMO143f-betaAMO1315r and CTO189f-Pf1053r primers; (e) nested amplification with 27f-1492r and CTO189f-CTO654r primers. Amplification products were characterized by denaturing gradient gel electrophoresis (DGGE) analysis after further amplification with 357f-GC-518r primers. DGGE profiles of soil communities were heterogeneous and depended on the approach followed. Ammonia oxidizer diversity was higher using approaches (b), (c) and (e) than using (a) and (d), where sequences of the most prominent bands showed similarities to nonammonia oxidizers. Profiles from marine sediments were more consistent, regardless of the approach adopted, and sequence analysis of excised bands indicated that these consisted of ammonia oxidizers only. The study demonstrates the importance of choice of primer, of screening for sequences of nontarget organisms and use of several approaches when characterizing microbial communities in natural environments.

  17. A Highly Practical Copper(I)/TEMPO Catalyst System for Chemoselective Aerobic Oxidation of Primary Alcohols

    PubMed Central

    Hoover, Jessica M.; Stahl, Shannon S.

    2011-01-01

    Aerobic oxidation reactions have been the focus of considerable attention, but their use in mainstream organic chemistry has been constrained by limitations in their synthetic scope and by practical factors, such as the use of pure O2 as the oxidant or complex catalyst synthesis. Here, we report a new (bpy)CuI/TEMPO catalyst system that enables efficient and selective aerobic oxidation of a broad range of primary alcohols, including allylic, benzylic and aliphatic derivatives, to the corresponding aldehydes using readily available reagents, at room temperature with ambient air as the oxidant. The catalyst system is compatible with a wide range of functional groups and the high selectivity for 1° alcohols enables selective oxidation of diols that lack protecting groups. PMID:21861488

  18. Continuous measurements of ammonia, nitrous oxide and methane from air scrubbers at pig housing facilities.

    PubMed

    Van der Heyden, C; Brusselman, E; Volcke, E I P; Demeyer, P

    2016-10-01

    Ammonia, largely emitted by agriculture, involves a great risk for eutrophication and acidification leading to biodiversity loss. Air scrubbers are widely applied to reduce ammonia emission from pig and poultry housing facilities, but it is not always clear whether their performance meets the requirements. Besides, there is a growing international concern for the livestock related greenhouse gases methane and nitrous oxide but hardly any data concerning their fate in air scrubbers are available. This contribution presents the results from measurement campaigns conducted at a chemical, a biological and a two-stage biological air scrubber installed at pig housing facilities in Flanders. Ammonia, nitrous oxide and methane at the inlet and outlet of the air scrubbers were monitored on-line during one week using a photoacoustic gas monitor, which allowed to investigate diurnal fluctuations in the removal performance of air scrubbers. Additionally, the homogeneity of the air scrubbers, normally checked by gas detection tubes, was investigated in more detail using the continuous data. The biological air scrubber with extra nitrification tank performed well in terms of ammonia removal (86 ± 6%), while the two-stage air scrubber suffered from nitrifying bacteria inhibition. In the chemical air scrubber the pH was not kept constant, lowering the ammonia removal efficiency. A lower ammonia removal efficiency was found during the day, when the ventilation rate was the highest. Nitrous oxide was produced inside the biological and two-stage scrubber, resulting in an increased outlet concentration of more than 200%. Methane could not be removed in the different air scrubbers because of its low water solubility. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Effects of temperature and fertilizer on activity and community structure of soil ammonia oxidizers.

    PubMed

    Avrahami, Sharon; Liesack, Werner; Conrad, Ralf

    2003-08-01

    We investigated the effect of temperature on the activity of soil ammonia oxidizers caused by changes in the availability of ammonium and in the microbial community structure. Both short (5 days) and long (6.5, 16 and 20 weeks) incubation of an agricultural soil resulted in a decrease in ammonium concentration that was more pronounced at temperatures between 10 and 25 degrees C than at either 4 degrees C or 30-37 degrees C. Consistently, potential nitrification was higher between 10 and 25 degrees C than at either 4 degrees C or 37 degrees C. However, as long as ammonium was not limiting, release rates of N2O increased monotonously between 4 and 37 degrees C after short-term temperature adaptation, with nitrification accounting for about 35-50% of the N2O production between 4 and 25 degrees C. In order to see whether temperature may also affect the community structure of ammonia oxidizers, we studied moist soil during long incubation at low and high concentrations of commercial fertilizer. The soil was also incubated in buffered (pH 7) slurry amended with urea. Communities of ammonia oxidizers were assayed by denaturant gradient gel electrophoresis (DGGE) of the amoA gene coding for the alpha subunit of ammonia monooxygenase. We found that a polymerase chain reaction (PCR) system using a non-degenerated reverse primer (amoAR1) gave the best results. Community shifts occurred in all soil treatments after 16 weeks of incubation. The community shifts were obviously influenced by the different fertilizer treatments, indicating that ammonium was a selective factor for different ammonia oxidizer populations. Temperature was also a selective factor, in particular as community shifts were also observed in the soil slurries, in which ammonium concentrations and pH were better controlled. Cloning and sequencing of selected DGGE bands indicated that amoA sequences belonging to Nitrosospira cluster 1 were dominant at low temperatures (4-10 degrees C), but were absent after

  20. A novel marine nitrite-oxidizing Nitrospira species from Dutch coastal North Sea water

    PubMed Central

    Haaijer, Suzanne C. M.; Ji, Ke; van Niftrik, Laura; Hoischen, Alexander; Speth, Daan; Jetten, Mike S. M.; Damsté, Jaap S. Sinninghe; Op den Camp, Huub J. M.

    2013-01-01

    Marine microorganisms are important for the global nitrogen cycle, but marine nitrifiers, especially aerobic nitrite oxidizers, remain largely unexplored. To increase the number of cultured representatives of marine nitrite-oxidizing bacteria (NOB), a bioreactor cultivation approach was adopted to first enrich nitrifiers and ultimately nitrite oxidizers from Dutch coastal North Sea water. With solely ammonia as the substrate an active nitrifying community consisting of novel marine Nitrosomonas aerobic ammonia oxidizers (ammonia-oxidizing bacteria) and Nitrospina and Nitrospira NOB was obtained which converted a maximum of 2 mmol of ammonia per liter per day. Switching the feed of the culture to nitrite as a sole substrate resulted in a Nitrospira NOB dominated community (approximately 80% of the total microbial community based on fluorescence in situ hybridization and metagenomic data) converting a maximum of 3 mmol of nitrite per liter per day. Phylogenetic analyses based on the 16S rRNA gene indicated that the Nitrospira enriched from the North Sea is a novel Nitrospira species with Nitrospira marina as the next taxonomically described relative (94% 16S rRNA sequence identity). Transmission electron microscopy analysis revealed a cell plan typical for Nitrospira species. The cytoplasm contained electron light particles that might represent glycogen storage. A large periplasmic space was present which was filled with electron dense particles. Nitrospira-targeted polymerase chain reaction analyses demonstrated the presence of the enriched Nitrospira species in a time series of North Sea genomic DNA samples. The availability of this new Nitrospira species enrichment culture facilitates further in-depth studies such as determination of physiological constraints, and comparison to other NOB species. PMID:23515432

  1. Bioinspired organocatalytic aerobic C-H oxidation of amines with an ortho-quinone catalyst.

    PubMed

    Qin, Yan; Zhang, Long; Lv, Jian; Luo, Sanzhong; Cheng, Jin-Pei

    2015-03-20

    A simple bioinspired ortho-quinone catalyst for the aerobic oxidative dehydrogenation of amines to imines is reported. Without any metal cocatalysts, the identified optimal ortho-quinone catalyst enables the oxidations of α-branched primary amines and cyclic secondary amines. Mechanistic studies have disclosed the origins of different performances of ortho-quinone vs para-quinone in biomimetic amine oxidations.

  2. Stimulating ammonia oxidizing bacteria (AOB) activity drives the ammonium oxidation rate in a constructed wetland (CW).

    PubMed

    Su, Yu; Wang, Weidong; Wu, Di; Huang, Wei; Wang, Mengzi; Zhu, Guibing

    2018-05-15

    An integrated approach to document high ammonium oxidation rate in Guanjinggang constructed wetland (GJG-CW) was performed and the results showed that the substantial ammonium oxidation rate could be obtained by enhancing Ammonia Oxidizing Bacteria (AOB) activity rather than Ammonia Oxidizing Archaea (AOA) activity. In the plant-bed/ditch system, ditch center and plant-bed fringe were two active zones for NH 4 + -N removal with ammonium oxidation rate peaking at 2.98±0.04 and 2.15±0.02mgNkg -1 d -1 , respectively. The enhanced AOB activity were achieved by increasing water level fluctuations, extending hydraulic retention time (HRT) and stimulating substrate availability, which subsequently enhanced NH 4 + -N removal by 34.06% in GJG-CW. However, the high AOB activity was not correlated with high AOB abundance, but was instead mostly determined by specific AOB taxa, particularly Nitrosomonas, which dominated in the active AOB. The increased cell-specific AOA activity and high AOA diversity were also achieved using those engineering measures. Although the AOA activity decreased overall with extended HRT and increased NH 4 + -N contents in GJG-CW, AOA still played a major role on ammonium oxidation in plant-bed soil. The study illustrated that artificially enhancing AOB activity and certain species in anthropogenically polluted water ecosystems would be an effective strategy to improve NH 4 + -N removal. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Low intensity aerobic exercise and oxidative stress markers in older adults.

    PubMed

    Bouzid, Mohamed A; Hammouda, Omar; Matran, Régis; Robin, Sophie; Fabre, Claudine

    2014-10-01

    This comparative study examined the effects of regular low intensity aerobic exercise on oxidative stress markers in older adults. The study was carried out on 15 sedentary subjects (age: 65.1 ± 3.5 years) versus 18 subjects performing fitness exercises (age: 65.8 ± 3.3 years). Before and after an incremental exercise test, oxidative stress markers were assessed. Superoxide dismutase was higher at rest and at the recovery for the physically active subjects compared with sedentary subjects (p < .05). At recovery, glutathione peroxidase and α -Tocopherol increased significantly above the resting values only in the active group (p < .05). Malondialdehyde had increased in both groups (p < .01), associated with a higher level in the sedentary group (p < .05) at the recovery. These data suggest that low intensity aerobic exercise may be useful to prevent the decline of antioxidants linked with aging.

  4. Impact of aerobic exercise on cognitive impairment and oxidative stress markers in methamphetamine-dependent patients.

    PubMed

    Zhang, Kai; Zhang, Qiaoyang; Jiang, Haifeng; Du, Jiang; Zhou, Chenglin; Yu, Shunying; Hashimoto, Kenji; Zhao, Min

    2018-03-17

    This study aimed to investigate whether 12-week moderate-intensity aerobic exercise has beneficial effects on oxidative stress markers in blood and on cognitive functions in patients who have methamphetamine dependence. Serum levels of oxidative stress markers, including total anti-oxidation capability, super oxide dismutase (SOD), catalase (CAT), and methane dicarboxylic aldehyde (MDA), were measured at baseline (all participants) and the 12-week follow-up (methamphetamine-dependent patients). Serum levels of CAT and MDA in methamphetamine-dependent patients (n = 68) were higher than those in healthy controls (n = 35) at baseline. Furthermore, the international shopping list (ISL) task scores of methamphetamine-dependent patients were significantly lower than those of the controls, indicating verbal memory deficits in methamphetamine-dependent patients. Although there were no significant interactions for all cognitive function scores, aerobic exercise improved the processing speed in methamphetamine-dependent patients. Of interest, aerobic exercise significantly attenuated a spontaneous increase in serum MDA levels in methamphetamine-dependent patients after 12-weeks of abstinence. In conclusion, this study showed that methamphetamine-dependent patients with verbal learning and memory deficits have higher serum levels of MDA, and that a 12-week aerobic exercise program may have beneficial effects on the processing speed as well as blood lipid peroxidation in methamphetamine-dependent patients. Copyright © 2018. Published by Elsevier B.V.

  5. Different Recovery Processes of Soil Ammonia Oxidizers from Flooding Disturbance.

    PubMed

    Ye, Fei; Ma, Mao-Hua; Op den Camp, Huub J M; Chatzinotas, Antonis; Li, Lei; Lv, Ming-Quan; Wu, Sheng-Jun; Wang, Yu

    2018-04-11

    Understanding how microorganisms respond to environmental disturbance is one of the key focuses in microbial ecology. Ammonia-oxidizing bacteria (AOB) and archaea (AOA) are responsible for ammonia oxidation which is a crucial step in the nitrogen cycle. Although the physiology, distribution, and activity of AOA and AOB in soil have been extensively investigated, their recovery from a natural disturbance remains largely unknown. To assess the recovery capacities, including resistance and resilience, of AOA and AOB, soil samples were taken from a reservoir riparian zone which experienced periodically water flooding. The samples were classified into three groups (flooding, recovery, and control) for a high-throughput sequencing and quantitative PCR analysis. We used a relative quantitative index of both the resistance (RS) and resilience (RL) to assess the variation of gene abundance, alpha-diversity, and community composition. The AOA generally demonstrated a better recovery capability after the flooding disturbance compared to AOB. In particular, AOA were more resilient after the flooding disturbance. Taxa within the AOA and AOB showed different RS and RL values, with the most abundant taxa showing in general the highest RS indices. Soil NH 4 + and Fe 2+ /Fe 3+ were the main variables controlling the key taxa of AOA and AOB and probably influenced the resistance and resilience properties of AOA and AOB communities. The distinct mechanisms of AOA and AOB in maintaining community stability against the flooding disturbance might be linked to the different life-history strategies: the AOA community was more likely to represent r-strategists in contrast to the AOB community following a K-life strategy. Our results indicated that the AOA may play a vital role in ammonia oxidation in a fluctuating habitat and contribute to the stability of riparian ecosystem.

  6. Steady-state voltammetry of hydroxide ion oxidation in aqueous solutions containing ammonia.

    PubMed

    Daniele, Salvatore; Baldo, M Antonietta; Bragato, Carlo; Abdelsalam, Mamdouh Elsayed; Denuault, Guy

    2002-07-15

    An oxidation process observed in dilute aqueous solutions of ammonia was investigated under steady-state conditions with gold microelectrodes with radii in the range 2.5-30 microm. Over the ammonia concentration range 0.1-10 mM, a well-defined voltammetric wave was observed at approximately 1.4 V versus Ag/AgCl. It was attributed to the oxidation of hydroxide ions that arise from the dissociation of the weak base. The steady-state limiting current was found to depend on the concentration of supporting electrolyte, and in solution with low electrolyte, it was enhanced by migration contribution, as expected for a negatively charged species that oxidizes on a positively charged electrode. In addition, the steady-state limiting current was proportional to both the ammonia concentration and the electrode radius. The overall electrode process was analyzed in terms of a CE mechanism (homogeneous chemical reaction preceding the heterogeneous electron transfer) with a fast chemical reaction when measurements were carried out in solutions containing NH3 at < or = 5 mM and with electrodes having a radius of > or = 5 microm. This was ascertained by comparing experimental and theoretical data obtained by simulation. The formation of the soluble complex species Au(NH3)2+ was also considered as a possible alternative to explain the presence of the oxidation wave. This process however was ruled out, as the experimental data did not fit theoretical predictions in any of the conditions employed in the investigation. Instead, the direct oxidation of NH3, probably to N2O, was invoked to explain the anomalous currents found when the CE process was strongly kinetically hindered. Throughout this study, a parallel was made between the CE mechanism investigated here and that known to occur during the hydrogen evolution reaction from weak acids.

  7. Revealing the halide effect on the kinetics of the aerobic oxidation of Cu(I) to Cu(II)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Deng, Yi; Zhang, Guanghui; Qi, Xiaotian

    2015-01-01

    In situ infrared (IR) and X-ray absorption near-edge structure (XANES) spectroscopic investigations reveal that different halide ligands have distinct effects on the aerobic oxidation of Cu(I) to Cu(II) in the presence of TMEDA (tetramethylethylenediamine). The iodide ligand gives the lowest rate and thus leads to the lowest catalytic reaction rate of aerobic oxidation of hydroquinone to benzoquinone. Further DFT calculations suggest that oxidation of CuI–TMEDA involves a side-on transition state, while oxidation of CuCl–TMEDA involves an end-on transition state which has a lower activation energy.

  8. Age-related effect of aerobic exercise training on antioxidant and oxidative markers in the liver challenged by doxorubicin in rats.

    PubMed

    Ahmadian, Mehdi; Dabidi Roshan, Valiollah; Leicht, Anthony S

    2018-05-16

    The aims of the current study were to investigate the oxidant and antioxidant status of liver tissue challenged by doxorubicin and to examine the possible protective effects of aerobic exercise on doxorubicin-induced oxidative stress. Seventy-two rats were divided into three age groups (Young, Adult, and Elderly) with three treatment subgroups consisting of eight rats per age group: doxorubicin, aerobic exercise + doxorubicin, and aerobic exercise + saline. The experimental groups performed regular treadmill running for 3 weeks. Doxorubicin was administered by i.p. injection at a dosage of 20 mg kg -1 while the aerobic exercise + saline group received saline of a comparable volume. Heat shock protein 70, malondialdehyde, glutathione peroxidase, and protein carbonyl were determined from the liver homogenates following the intervention period. Treatment with doxorubicin induced hepatotoxicity in all groups with lower values of oxidative stress in young compared with the older groups. The inclusion of aerobic exercise training significantly increased heat shock protein 70 and antioxidant enzyme levels (glutathione peroxidase) whereas it decreased oxidative stress biomarkers (malondialdehyde and protein carbonyl) for all age groups. These results suggest that aerobic exercise training may be a potential, non-drug strategy to modulate doxorubicin-induced hepatotoxicity through its positive impact on antioxidant levels and oxidative stress biomarkers.

  9. Ammonia modification of activated carbon to enhance carbon dioxide adsorption: Effect of pre-oxidation

    NASA Astrophysics Data System (ADS)

    Shafeeyan, Mohammad Saleh; Daud, Wan Mohd Ashri Wan; Houshmand, Amirhossein; Arami-Niya, Arash

    2011-02-01

    A commercial granular activated carbon (GAC) was subjected to thermal treatment with ammonia for obtaining an efficient carbon dioxide (CO2) adsorbent. In general, CO2 adsorption capacity of activated carbon can be increased by introduction of basic nitrogen functionalities onto the carbon surface. In this work, the effect of oxygen surface groups before introduction of basic nitrogen functionalities to the carbon surface on CO2 adsorption capacity was investigated. For this purpose two different approaches of ammonia treatment without preliminary oxidation and amination of oxidized samples were studied. Modified carbons were characterized by elemental analysis and Fourier Transform Infrared spectroscopy (FT-IR) to study the impact of changes in surface chemistry and formation of specific surface groups on adsorption properties. The texture of the samples was characterized by conducting N2 adsorption/desorption at -196 °C. CO2 capture performance of the samples was investigated using a thermogravimetric analysis (TGA). It was found that in both modification techniques, the presence of nitrogen functionalities on carbon surface generally increased the CO2 adsorption capacity. The results indicated that oxidation followed by high temperature ammonia treatment (800 °C) considerably enhanced the CO2 uptake at higher temperatures.

  10. Competitive interactions between methane- and ammonia-oxidizing bacteria modulate carbon and nitrogen cycling in paddy soil

    NASA Astrophysics Data System (ADS)

    Zheng, Y.; Huang, R.; Wang, B. Z.; Bodelier, P. L. E.; Jia, Z. J.

    2014-06-01

    Pure culture studies have demonstrated that methanotrophs and ammonia oxidizers can both carry out the oxidation of methane and ammonia. However, the expected interactions resulting from these similarities are poorly understood, especially in complex, natural environments. Using DNA-based stable isotope probing and pyrosequencing of 16S rRNA and functional genes, we report on biogeochemical and molecular evidence for growth stimulation of methanotrophic communities by ammonium fertilization, and that methane modulates nitrogen cycling by competitive inhibition of nitrifying communities in a rice paddy soil. Pairwise comparison between microcosms amended with CH4, CH4+Urea, and Urea indicated that urea fertilization stimulated methane oxidation activity 6-fold during a 19-day incubation period, while ammonia oxidation activity was significantly suppressed in the presence of CH4. Pyrosequencing of the total 16S rRNA genes revealed that urea amendment resulted in rapid growth of Methylosarcina-like MOB, and nitrifying communities appeared to be partially inhibited by methane. High-throughput sequencing of the 13C-labeled DNA further revealed that methane amendment resulted in clear growth of Methylosarcina-related MOB while methane plus urea led to an equal increase in Methylosarcina and Methylobacter-related type Ia MOB, indicating the differential growth requirements of representatives of these genera. An increase in 13C assimilation by microorganisms related to methanol oxidizers clearly indicated carbon transfer from methane oxidation to other soil microbes, which was enhanced by urea addition. The active growth of type Ia methanotrops was significantly stimulated by urea amendment, and the pronounced growth of methanol-oxidizing bacteria occurred in CH4-treated microcosms only upon urea amendment. Methane addition partially inhibited the growth of Nitrosospira and Nitrosomonas in urea-amended microcosms, as well as growth of nitrite-oxidizing bacteria. These

  11. Influence of oxygen availability on the activities of ammonia-oxidizing archaea.

    PubMed

    Qin, Wei; Meinhardt, Kelley A; Moffett, James W; Devol, Allan H; Virginia Armbrust, E; Ingalls, Anitra E; Stahl, David A

    2017-06-01

    Recent studies point to the importance of oxygen (O 2 ) in controlling the distribution and activity of marine ammonia-oxidizing archaea (AOA), one of the most abundant prokaryotes in the ocean. The AOA are associated with regions of low O 2 tension in oceanic oxygen minimum zones (OMZs), and O 2 availability is suggested to influence their production of the ozone-depleting greenhouse gas nitrous oxide (N 2 O). We show that marine AOA available in pure culture sustain high ammonia oxidation activity at low μM O 2 concentrations, characteristic of suboxic regions of OMZs (<10 µM O 2 ), and that atmospheric concentrations of O 2 may inhibit the growth of some environmental populations. We quantify the increasing N 2 O production by marine AOA with decreasing O 2 tensions, consistent with the plausibility of an AOA contribution to the accumulation of N 2 O at the oxic-anoxic redox boundaries of OMZs. Variable sensitivity to peroxide also suggests that endogenous or exogenous reactive oxygen species are of importance in determining the environmental distribution of some populations. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

  12. Improved composting of poultry feces via supplementation with ammonia oxidizing archaea.

    PubMed

    Xie, Kaizhi; Jia, Xiaoshan; Xu, Peizhi; Huang, Xu; Gu, Wenjie; Zhang, Fabao; Yang, Shaohai; Tang, Shuanhu

    2012-09-01

    Ammonia-oxidizing archaea (AOA) play an important role in the oxidation of ammonia. However, the participation of AOA in the composting process has not been established. The addition of AOA to a compost mix was able to speed up both the onset of the hyperthermic phase and the composting time. The composition of the microflora and the relative abundance were determined by using denaturing gradient gel electrophoresis and quantitative real-time PCR, based on the presence of the archaeal amoA genes. The amplicon profiles allowed some of the major AOA species present in the final compost to be identified, and their relative abundance to be estimated from their amplification intensity. The lower pH during the lower temperature phase of compost served to enhance the nitrogen content of the final compost. The addition of AOA resulted in the expanding diversity of microflora species than that of the natural colonization. Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.

  13. Influence of Starvation on Potential Ammonia-Oxidizing Activity and amoA mRNA Levels of Nitrosospira briensis

    PubMed Central

    Bollmann, Annette; Schmidt, Ingo; Saunders, Aaron M.; Nicolaisen, Mette H.

    2005-01-01

    The effect of short-term ammonia starvation on Nitrosospira briensis was investigated. The ammonia-oxidizing activity was determined in a concentrated cell suspension with a NOx biosensor. The apparent half-saturation constant [Km(app)] value of the NH3 oxidation of N. briensis was 3 μM NH3 for cultures grown both in continuous and batch cultures as determined by a NOx biosensor. Cells grown on the wall of the vessel had a lower Km(app) value of 1.8 μM NH3. Nonstarving cultures of N. briensis showed potential ammonia-oxidizing activities of between 200 to 250 μM N h−1, and this activity decreased only slowly during starvation up to 10 days. Within 10 min after the addition of fresh NH4+, 100% activity was regained. Parallel with activity measurements, amoA mRNA and 16S rRNA were investigated. No changes were observed in the 16S rRNA, but a relative decrease of amoA mRNA was observed during the starvation period. During resuscitation, an increase in amoA mRNA expression was detected simultaneously. The patterns of the soluble protein fraction of a 2-week-starved culture of N. briensis showed only small differences in comparison to a nonstarved control. From these results we conclude that N. briensis cells remain in a state allowing fast recovery of ammonia-oxidizing activity after addition of NH4+ to a starved culture. Maintaining cells in this kind of active state could be the survival strategy of ammonia-oxidizing bacteria in nature under fluctuating NH4+ availability. PMID:15746329

  14. Effects of disinfectant fogging procedure on dust, ammonia concentration, aerobic bacteria and fungal spores in a farrowing-weaning room.

    PubMed

    Costa, Annamaria; Colosio, Claudio; Gusmara, Claudia; Sala, Vittorio; Guarino, Marcella

    2014-01-01

    In the last decades, large-scale swine production has led to intensive rearing systems in which air quality can be easily degraded by aerial contaminants that can pose a health risk to the pigs and farm workers. This study evaluated the effects of fogging disinfectant procedure on productive performance, ammonia and dust concentration, aerobic bacteria and fungal spores spreading in the farrowing-weaning room. This trial was conducted in 2 identical farrowing-weaning rooms of a piggery. In both rooms, 30 pregnant sows were lodged in individual cages. At 75 days of age, the piglets were moved to the fattening room. In the treated room, with the birth of the first suckling-pig, the fogging disinfection with diluted Virkon S was applied once a day in the experimental room per 15 minutes at 11:00. The fogging disinfectant treatment was switched between rooms at the end of the first trial period. Temperature, relative humidity, dust (TSP-RF fractions and number of particles), ammonia concentration and aerial contaminants (enterococci, Micrococcaeae and fungal spores) were monitored in both rooms. Ammonia concentration reduction induced by fogging disinfection was estimated 18%, total suspended particles and the respirable fraction were significantly lower in the experimental room. Fungal spores resulted in a significant reduction by the fogging procedure, together with dust respirable fraction and fine particulate matter abatement. The fogging disinfection procedure improved air quality in the piggery, thereby enhancing workers and animals health.

  15. Oxidative stress in response to aerobic and anaerobic power testing: influence of exercise training and carnitine supplementation.

    PubMed

    Bloomer, Richard J; Smith, Webb A

    2009-01-01

    The purpose of this study is to compare the oxidative stress response to aerobic and anaerobic power testing, and to determine the impact of exercise training with or without glycine propionyl-L-carnitine (GPLC) in attenuating the oxidative stress response. Thirty-two subjects were assigned (double blind) to placebo, GPLC-1 (1g PLC/d), GPLC-3 (3g PLC/d) for 8 weeks, plus aerobic exercise. Aerobic (graded exercise test: GXT) and anaerobic (Wingate cycle) power tests were performed before and following the intervention. Blood was taken before and immediately following exercise tests and analyzed for malondialdehyde (MDA), hydrogen peroxide (H2O2), and xanthine oxidase activity (XO). No interaction effects were noted. MDA was minimally effected by exercise but lower at rest for both GPLC groups following the intervention (p = 0.044). A time main effect was noted for H2O2 (p = 0.05) and XO (p = 0.003), with values increasing from pre- to postexercise. Both aerobic and anaerobic power testing increase oxidative stress to a similar extent. Exercise training plus GPLC can decrease resting MDA, but it has little impact on exercise-induced oxidative stress biomarkers.

  16. Moisture and temperature controls on nitrification differ among ammonia oxidizer communities from three alpine soil habitats

    USGS Publications Warehouse

    Osborne, Brooke B.; Baron, Jill S.; Wallenstein, Matthew D.

    2016-01-01

    Climate change is altering the timing and magnitude of biogeochemical fluxes in many high elevation ecosystems. The consequent changes in alpine nitrification rates have the potential to influence ecosystem scale responses. In order to better understand how changing temperature and moisture conditions may influence ammonia oxidizers and nitrification activity, we conducted laboratory incubations on soils collected in a Colorado watershed from three alpine habitats (glacial outwash, talus, and meadow). We found that bacteria, not archaea, dominated all ammonia oxidizer communities. Nitrification increased with moisture in all soils and under all temperature treatments. However, temperature was not correlated with nitrification rates in all soils. Site-specific temperature trends suggest the development of generalist ammonia oxidizer communities in soils with greater in situ temperature fluctuations and specialists in soils with more steady temperature regimes. Rapidly increasing temperatures and changing soil moisture conditions could explain recent observations of increased nitrate production in some alpine soils.

  17. Impact of oxidative stress defense on bacterial survival and morphological change in Campylobacter jejuni under aerobic conditions.

    PubMed

    Oh, Euna; McMullen, Lynn; Jeon, Byeonghwa

    2015-01-01

    Campylobacter jejuni, a microaerophilic foodborne pathogen, inescapably faces high oxygen tension during its transmission to humans. Thus, the ability of C. jejuni to survive under oxygen-rich conditions may significantly impact C. jejuni viability in food and food safety as well. In this study, we investigated the impact of oxidative stress resistance on the survival of C. jejuni under aerobic conditions by examining three mutants defective in key antioxidant genes, including ahpC, katA, and sodB. All the three mutants exhibited growth reduction under aerobic conditions compared to the wild-type (WT), and the ahpC mutant showed the most significant growth defect. The CFU reduction in the mutants was recovered to the WT level by complementation. Higher levels of reactive oxygen species were accumulated in C. jejuni under aerobic conditions than microaerobic conditions, and supplementation of culture media with an antioxidant recovered the growth of C. jejuni. The levels of lipid peroxidation and protein oxidation were significantly increased in the mutants compared to WT. Additionally, the mutants exhibited different morphological changes under aerobic conditions. The ahpC and katA mutants developed coccoid morphology by aeration, whereas the sodB mutant established elongated cellular morphology. Compared to microaerobic conditions, interestingly, aerobic culture conditions substantially induced the formation of coccoidal cells, and antioxidant treatment reduced the emergence of coccoid forms under aerobic conditions. The ATP concentrations and PMA-qPCR analysis supported that oxidative stress is a factor that induces the development of a viable-but-non-culturable state in C. jejuni. The findings in this study clearly demonstrated that oxidative stress resistance plays an important role in the survival and morphological changes of C. jejuni under aerobic conditions.

  18. [Immobilized ammonia-oxidizing bacteria Comamonas aquatic LNL3 and its partial nitrification characterization].

    PubMed

    Li, Zheng-kui; Shi, Lu-na; Yang, Zhu-you; Zhang, Xiao-jiao; Wang, Yue-ming; Chen, Qi-chun; Wu, Kai

    2009-10-15

    A new kind of ammonia-oxidizing bacteria (AOB)-Comamonas aquatic LNL3 was screened out and immobilized by Poly (HEA)-Poly (HEMA) copolymer carrier using irradiation techniques. Four kinds of impact factors on short-cut nitrification, including temperature, pH, DO and free ammonia (FA) concentration had been investigated. The result showed that AOB-Comamonas aquatic LNL3 had short-cut nitrification capability and the optimal temperature, pH, DO and FA concentration were 30 degrees C, 8.5, 4.03 mg/L and 9 mg/L respectively. Corresponding to above results, ammonia nitrogen removal rate and short-cut nitrification efficiency were 93.52%, 94.73%; 79.74%, 94.67%; 91.17%, 94.66% and 90%, 94.4% respectively.

  19. Nitrous oxide and ammonia emissions from injected and broadcast applied dairy slurry

    USDA-ARS?s Scientific Manuscript database

    Trade-offs associated with surface application or injection of manure pose important environmental and agronomic concerns. Manure injection can conserve nitrogen (N) by decreasing ammonia volatilization. However, the injection band also creates conditions, which potentially favor nitrous oxide produ...

  20. Efficiency of autothermal thermophilic aerobic digestion under two different oxygen flow rates.

    PubMed

    Aynur, Sebnem Koyunluoglu; Riffat, Rumana; Murthy, Sudhir

    2014-01-01

    The objective of this research was to understand the influence of oxygenation at two different oxygen flow rates (0.105 and 0.210 L/L/h) on autothermal thermophilic aerobic digestion (ATAD), and on the overall performance of Dual Digestion (DD). Profile experiments on an ATAD reactor showed that a significant portion of volatile fatty acids and ammonia were produced in the first 12 h period, and both followed first order kinetics. Ammonia concentrations of ATAD effluent were 1015 mg/L and 1450 mg/L, respectively, at the two oxygenation rates. Ammonia production was not complete in the ATAD reactor at the lower oxygenation rate. However, it was sufficient to maximize volatile solids reduction in the DD process. The biological heat of oxidations were 14,300 J/g Volatile Solids (VS) removed and 15,900 J/g VS removed for the two oxygen flow rates, respectively. The ATAD step provided enhanced digestion for the DD process with higher volatile solids removal and methane yield when compared to conventional digestion.

  1. CuPt and CuPtRu Nanostructures for Ammonia Oxidation Reaction

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Manso, R H.; Song, L.; Liang, Z.

    Liquid fuels, such as methanol, ethanol, and ammonia, are attractive alternative to hydrogen for fuel cells due to their lower costs for storage and distribution. However, lack of sufficiently active catalysts for their oxidation reactions is a roadblock. Our previous study found that Pt 3Cu nanodendrites yielded higher activity and durability than Pt nanoparticles for methanol oxidation reaction (MOR) in acid. In this study, we synthesized two types of nanostructures of CuPt and CuPtRu catalysts via seed-mediated growth of Pt and Ru on Cu and tested their performance for ammonia oxidation reaction (AOR) in alkaline solution. Unlike for MOR, themore » nanodendrites do not promote AOR activity - CuPt performs similar to Pt and CuPtRu is less active than Pt. Interestingly, the AOR peak current is increased by 64% on CuPt nanowires and 330% on CuPtRu nanowires as compared to Pt nanoparticles. These results suggest that AOR prefers extended surface on long nanowires, distinctly differing from MOR. This can be contributed to two factors: NH 3 oxidization to N 2 involves dimerization of two N-containing intermediates to form the N-N bond and diffusion batters for adsorbed intermediates are generally lower on terrace than at low-coordination sites. This demonstrated strong effect of surface morphology will be further studied and utilized in developing advanced AOR nanocatalysts.« less

  2. CuPt and CuPtRu Nanostructures for Ammonia Oxidation Reaction

    DOE PAGES

    Manso, R H.; Song, L.; Liang, Z.; ...

    2018-04-01

    Liquid fuels, such as methanol, ethanol, and ammonia, are attractive alternative to hydrogen for fuel cells due to their lower costs for storage and distribution. However, lack of sufficiently active catalysts for their oxidation reactions is a roadblock. Our previous study found that Pt 3Cu nanodendrites yielded higher activity and durability than Pt nanoparticles for methanol oxidation reaction (MOR) in acid. In this study, we synthesized two types of nanostructures of CuPt and CuPtRu catalysts via seed-mediated growth of Pt and Ru on Cu and tested their performance for ammonia oxidation reaction (AOR) in alkaline solution. Unlike for MOR, themore » nanodendrites do not promote AOR activity - CuPt performs similar to Pt and CuPtRu is less active than Pt. Interestingly, the AOR peak current is increased by 64% on CuPt nanowires and 330% on CuPtRu nanowires as compared to Pt nanoparticles. These results suggest that AOR prefers extended surface on long nanowires, distinctly differing from MOR. This can be contributed to two factors: NH 3 oxidization to N 2 involves dimerization of two N-containing intermediates to form the N-N bond and diffusion batters for adsorbed intermediates are generally lower on terrace than at low-coordination sites. This demonstrated strong effect of surface morphology will be further studied and utilized in developing advanced AOR nanocatalysts.« less

  3. High diversity of ammonia-oxidizing archaea in permanent and seasonal oxygen-deficient waters of the eastern South Pacific.

    PubMed

    Molina, Verónica; Belmar, Lucy; Ulloa, Osvaldo

    2010-09-01

    The community structure of putative aerobic ammonia-oxidizing archaea (AOA) was explored in two oxygen-deficient ecosystems of the eastern South Pacific: the oxygen minimum zone off Peru and northern Chile (11°S-20°S), where permanent suboxic and low-ammonium conditions are found at intermediate depths, and the continental shelf off central Chile (36°S), where seasonal oxygen-deficient and relatively high-ammonium conditions develop in the water column, particularly during the upwelling season. The AOA community composition based on the ammonia monooxygenase subunit A (amoA) genes changed according to the oxygen concentration in the water column and the ecosystem studied, showing a higher diversity in the seasonal low-oxygen waters. The majority of the archaeal amoA genotypes was affiliated to the uncultured clusters A (64%) and B (35%), with Cluster A AOA being mainly associated with higher oxygen and ammonium concentrations and Cluster B AOA with permanent oxygen- and ammonium-poor waters. Q-PCR assays revealed that AOA are an abundant community (up to 10(5) amoA copies ml(-1) ), while bacterial amoA genes from β proteobacteria were undetected. Our results thus suggest that a diverse uncultured AOA community, for which, therefore, we do not have any physiological information, to date, is an important component of the nitrifying community in oxygen-deficient marine ecosystems, and particularly in rich coastal upwelling ones. © 2010 Society for Applied Microbiology and Blackwell Publishing Ltd.

  4. AMMONIA REMOVAL AND NITROUS OXIDE PRODUCTION IN GAS-PHASE COMPOST BIOFILTERS

    USDA-ARS?s Scientific Manuscript database

    Biofiltration technology is widely utilized for treating ammonia gas (NH3), with one of its potential detrimental by-products being nitrous oxide (N2O), a greenhouse gas approximately 300 times more reactive to infrared than CO2. The present work intends to provide the relation between NH3 removal d...

  5. Evidence for decoupled electron and proton transfer in the electrochemical oxidation of ammonia on Pt(100)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Katsounaros, Ioannis; Chen, Ting; Gewirth, Andrew A.

    The two traditional mechanisms of the electrochemical ammonia oxidation consider only concerted proton-electron transfer elementary steps and thus they predict that the rate–potential relationship is independent of the pH on the pH-corrected RHE potential scale. In this letter we show that this is not the case: the increase of the solution pH shifts the onset of the NH 3-to-N 2 oxidation on Pt(100) to lower potentials and also leads to higher surface concentration of formed N Oad before the latter is oxidized to nitrite. Therefore, we present a new mechanism for the ammonia oxidation which incorporates a deprotonation step occurringmore » prior to the electron transfer. The deprotonation step yields a negatively charged surface-adsorbed species which is discharged in a subsequent electron transfer step before the N–N bond formation. The negatively charged species is thus a precursor for the formation of N 2 and NO. The new mechanism should be a future guide for computational studies aiming at the identification of intermediates and corresponding activation barriers for the elementary steps. As a result, ammonia oxidation is a new example of a bond-forming reaction on (100) terraces which involves decoupled proton-electron transfer.« less

  6. Evidence for decoupled electron and proton transfer in the electrochemical oxidation of ammonia on Pt(100)

    DOE PAGES

    Katsounaros, Ioannis; Chen, Ting; Gewirth, Andrew A.; ...

    2016-01-12

    The two traditional mechanisms of the electrochemical ammonia oxidation consider only concerted proton-electron transfer elementary steps and thus they predict that the rate–potential relationship is independent of the pH on the pH-corrected RHE potential scale. In this letter we show that this is not the case: the increase of the solution pH shifts the onset of the NH 3-to-N 2 oxidation on Pt(100) to lower potentials and also leads to higher surface concentration of formed N Oad before the latter is oxidized to nitrite. Therefore, we present a new mechanism for the ammonia oxidation which incorporates a deprotonation step occurringmore » prior to the electron transfer. The deprotonation step yields a negatively charged surface-adsorbed species which is discharged in a subsequent electron transfer step before the N–N bond formation. The negatively charged species is thus a precursor for the formation of N 2 and NO. The new mechanism should be a future guide for computational studies aiming at the identification of intermediates and corresponding activation barriers for the elementary steps. As a result, ammonia oxidation is a new example of a bond-forming reaction on (100) terraces which involves decoupled proton-electron transfer.« less

  7. Effects of bioaugmentation in para-nitrophenol-contaminated soil on the abundance and community structure of ammonia-oxidizing bacteria and archaea.

    PubMed

    Chi, Xiang-Qun; Liu, Kun; Zhou, Ning-Yi

    2015-07-01

    Pseudomonas sp. strain WBC-3 mineralizes the priority pollutant para-nitrophenol (PNP) and releases nitrite (NO2 (-)), which is probably involved in the nitrification. In this study, the rate of PNP removal in soil bioaugmented with strain WBC-3 was more accelerated with more NO2 (-) accumulation than in uninoculated soils. Strain WBC-3 survived well and remained stable throughout the entire period. Real-time polymerase chain reaction (real-time PCR) indicated a higher abundance of ammonia-oxidizing bacteria (AOB) than ammonia-oxidizing archaea (AOA), suggesting that AOB played a greater role in nitrification in the original sampled soil. Real-time PCR and multivariate analysis based on the denaturing gradient gel electrophoresis showed that PNP contamination did not significantly alter the abundance and community structure of ammonia oxidizers except for inhibiting the AOB abundance. Bioaugmentation of PNP-contaminated soil showed a significant effect on AOB populations and community structure as well as AOA populations. In addition, ammonium (NH4 (+)) variation was found to be the primary factor affecting the AOB community structure, as determined by the correlation between the community structures of ammonia oxidizers and environmental factors. It is here proposed that the balance between archaeal and bacterial ammonia oxidation could be influenced significantly by the variation in NH4 (+) levels as caused by bioaugmentation of contaminated soil by a pollutant containing nitrogen.

  8. Microgravity Effects on Chronoamperometric Ammonia Oxidation Reaction at Platinum Nanoparticles on Modified Mesoporous Carbon Supports

    NASA Astrophysics Data System (ADS)

    Poventud-Estrada, Carlos M.; Acevedo, Raúl; Morales, Camila; Betancourt, Luis; Diaz, Diana C.; Rodriguez, Manuel A.; Larios, Eduardo; José-Yacaman, Miguel; Nicolau, Eduardo; Flynn, Michael; Cabrera, Carlos R.

    2017-10-01

    The effect of microgravity on the electrochemical oxidation of ammonia at platinum nanoparticles supported on modified mesoporous carbons (MPC) with three different pore diameters (64, 100, and 137 Å) was studied via the chronoamperometric technique in a half-cell. The catalysts were prepared by a H2 reductive process of PtCl6^{4-} in presence of the mesoporous carbon support materials. A microgravity environment was obtained with an average gravity of less than 0.02 g created aboard an airplane performing parabolic maneuvers. Results show the chronoamperommetry of the ammonia oxidation reaction in 1.0 M NH4OH at 0.60 V vs. RHE under microgravity conditions. The current density, in all three catalysts, decreased while in microgravity conditions when compared to ground based experiments. Under microgravity, all three catalysts yielded a decrease in ammonia oxidation reaction current density between 25 to 63% versus terrestrial experimental results, in time scales between 1 and 15 s. The Pt catalyst prepared with mesoporous carbon of 137 Å porous showed the smallest changes, between 25 to 48%. Nanostructuring catalyst materials have an effect on the level of current density decrease under microgravity conditions.

  9. Bioaugmentation of Syntrophic Acetate-Oxidizing Culture in Biogas Reactors Exposed to Increasing Levels of Ammonia

    PubMed Central

    Westerholm, Maria; Levén, Lotta

    2012-01-01

    The importance of syntrophic acetate oxidation for process stability in methanogenic systems operating at high ammonia concentrations has previously been emphasized. In this study we investigated bioaugmentation of syntrophic acetate-oxidizing (SAO) cultures as a possible method for decreasing the adaptation period of biogas reactors operating at gradually increased ammonia concentrations (1.5 to 11 g NH4+-N/liter). Whole stillage and cattle manure were codigested semicontinuously for about 460 days in four mesophilic anaerobic laboratory-scale reactors, and a fixed volume of SAO culture was added daily to two of the reactors. Reactor performance was evaluated in terms of biogas productivity, methane content, pH, alkalinity, and volatile fatty acid (VFA) content. The decomposition pathway of acetate was analyzed by isotopic tracer experiments, and population dynamics were monitored by quantitative PCR analyses. A shift in dominance from aceticlastic methanogenesis to SAO occurred simultaneously in all reactors, indicating no influence by bioaugmentation on the prevailing pathway. Higher abundances of Clostridium ultunense and Tepidanaerobacter acetatoxydans were associated with bioaugmentation, but no influence on Syntrophaceticus schinkii or the methanogenic population was distinguished. Overloading or accumulation of VFA did not cause notable dynamic effects on the population. Instead, the ammonia concentration had a substantial impact on the abundance level of the microorganisms surveyed. The addition of SAO culture did not affect process performance or stability against ammonia inhibition, and all four reactors deteriorated at high ammonia concentrations. Consequently, these findings further demonstrate the strong influence of ammonia on the methane-producing consortia and on the representative methanization pathway in mesophilic biogas reactors. PMID:22923397

  10. Diversity and abundance of ammonia oxidizing archaea in tropical compost systems

    PubMed Central

    de Gannes, Vidya; Eudoxie, Gaius; Dyer, David H.; Hickey, William J.

    2012-01-01

    Composting is widely used to transform waste materials into valuable agricultural products. In the tropics, large quantities of agricultural wastes could be potentially useful in agriculture after composting. However, while microbiological processes of composts in general are well established, relatively little is known about microbial communities that may be unique to these in tropical systems, particularly nitrifiers. The recent discovery of ammonia oxidizing archaea (AOA) has changed the paradigm of nitrification being initiated solely by ammonia oxidizing bacteria. In the present study, AOA abundance and diversity was examined in composts produced from combinations of plant waste materials common in tropical agriculture (rice straw, sugar cane bagasse, and coffee hulls), which were mixed with either cow- or sheep-manure. The objective was to determine how AOA abundance and diversity varied as a function of compost system and time, the latter being a contrast between the start of the compost process (mesophilic phase) and the finished product (mature phase). The results showed that AOA were relatively abundant in composts of tropical agricultural wastes, and significantly more so than were the ammonia-oxidizing bacteria. Furthermore, while the AOA communities in the composts were predominatly group I.1b, the communities were diverse and exhibited structures that diverged between compost types and phases. These patterns could be taken as indicators of the ecophysiological diversity in the soil AOA (group I.1b), in that significantly different AOA communties developed when exposed to varying physico-chemical environments. Nitrification patterns and levels differed in the composts which, for the mature material, could have significant effects on its performance as a plant growth medium. Thus, it will also be important to determine the association of AOA (and diversity in their communities) with nitrification in these systems. PMID:22787457

  11. Trace metal pyritization variability in response to mangrove soil aerobic and anaerobic oxidation processes.

    PubMed

    Machado, W; Borrelli, N L; Ferreira, T O; Marques, A G B; Osterrieth, M; Guizan, C

    2014-02-15

    The degree of iron pyritization (DOP) and degree of trace metal pyritization (DTMP) were evaluated in mangrove soil profiles from an estuarine area located in Rio de Janeiro (SE Brazil). The soil pH was negatively correlated with redox potential (Eh) and positively correlated with DOP and DTMP of some elements (Mn, Cu and Pb), suggesting that pyrite oxidation generated acidity and can affect the importance of pyrite as a trace metal-binding phase, mainly in response to spatial variability in tidal flooding. Besides these aerobic oxidation effects, results from a sequential extraction analyses of reactive phases evidenced that Mn oxidized phase consumption in reaction with pyrite can be also important to determine the pyritization of trace elements. Cumulative effects of these aerobic and anaerobic oxidation processes were evidenced as factors affecting the capacity of mangrove soils to act as a sink for trace metals through pyritization processes. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. Analysis of nitrification in agricultural soil and improvement of nitrogen circulation with autotrophic ammonia-oxidizing bacteria.

    PubMed

    Matsuno, Toshihide; Horii, Sachie; Sato, Takanobu; Matsumiya, Yoshiki; Kubo, Motoki

    2013-02-01

    Accumulations of inorganic nitrogen (NH₄⁺, NO₂⁻, and NO₃⁻) were analyzed to evaluate the nitrogen circulation activity in 76 agricultural soils. Accumulation of NH₄⁺ was observed, and the reaction of NH₄⁺→ NO₂⁻ appeared to be slower than that of NO₂⁻ → NO₃⁻ in agricultural soil. Two autotrophic and five heterotrophic ammonia-oxidizing bacteria (AOB) were isolated and identified from the soils, and the ammonia-oxidizing activities of the autotrophic AOB were 1.0 × 10³-1.0 × 10⁶ times higher than those of heterotrophic AOB. The relationship between AOB number, soil bacterial number, and ammonia-oxidizing activity was investigated with 30 agricultural soils. The ratio of autotrophic AOB number was 0.00032-0.26% of the total soil bacterial number. The soil samples rich in autotrophic AOB (>1.0 × 10⁴ cells/g soil) had a high nitrogen circulation activity, and additionally, the nitrogen circulation in the agricultural soil was improved by controlling the autotrophic AOBs.

  13. Evaluation of autotrophic growth of ammonia-oxidizers associated with granular activated carbon used for drinking water purification by DNA-stable isotope probing.

    PubMed

    Niu, Jia; Kasuga, Ikuro; Kurisu, Futoshi; Furumai, Hiroaki; Shigeeda, Takaaki

    2013-12-01

    Nitrification is an important biological function of granular activated carbon (GAC) used in advanced drinking water purification processes. Newly discovered ammonia-oxidizing archaea (AOA) have challenged the traditional understanding of ammonia oxidation, which considered ammonia-oxidizing bacteria (AOB) as the sole ammonia-oxidizers. Previous studies demonstrated the predominance of AOA on GAC, but the contributions of AOA and AOB to ammonia oxidation remain unclear. In the present study, DNA-stable isotope probing (DNA-SIP) was used to investigate the autotrophic growth of AOA and AOB associated with GAC at two different ammonium concentrations (0.14 mg N/L and 1.4 mg N/L). GAC samples collected from three full-scale drinking water purification plants in Tokyo, Japan, had different abundance of AOA and AOB. These samples were fed continuously with ammonium and (13)C-bicarbonate for 14 days. The DNA-SIP analysis demonstrated that only AOA assimilated (13)C-bicarbonate at low ammonium concentration, whereas AOA and AOB exhibited autotrophic growth at high ammonium concentration. This indicates that a lower ammonium concentration is preferable for AOA growth. Since AOA could not grow without ammonium, their autotrophic growth was coupled with ammonia oxidation. Overall, our results point towards an important role of AOA in nitrification in GAC filters treating low concentration of ammonium. Copyright © 2013 Elsevier Ltd. All rights reserved.

  14. Inhibitory effects of C2 to C10 1-alkynes on ammonia oxidation in two Nitrososphaera species.

    PubMed

    Taylor, A E; Taylor, K; Tennigkeit, B; Palatinszky, M; Stieglmeier, M; Myrold, D D; Schleper, C; Wagner, M; Bottomley, P J

    2015-03-01

    A previous study showed that ammonia oxidation by the Thaumarchaeota Nitrosopumilus maritimus (group 1.1a) was resistant to concentrations of the C8 1-alkyne, octyne, which completely inhibits activity by ammonia-oxidizing bacteria. In this study, the inhibitory effects of octyne and other C2 to C10 1-alkynes were evaluated on the nitrite production activity of two pure culture isolates from Thaumarchaeota group 1.1b, Nitrososphaera viennensis strain EN76 and Nitrososphaera gargensis. Both N. viennensis and N. gargensis were insensitive to concentrations of octyne that cause complete and irreversible inactivation of nitrite production by ammonia-oxidizing bacteria. However, octyne concentrations (≥20 μM) that did not inhibit N. maritimus partially inhibited nitrite production in N. viennensis and N. gargensis in a manner that did not show the characteristics of irreversible inactivation. In contrast to previous studies with an ammonia-oxidizing bacterium, Nitrosomonas europaea, octyne inhibition of N. viennensis was: (i) fully and immediately reversible, (ii) not competitive with NH4 (+), and (iii) without effect on the competitive interaction between NH4 (+) and acetylene. Both N. viennensis and N. gargensis demonstrated the same overall trend in regard to 1-alkyne inhibition as previously observed for N. maritimus, being highly sensitive to ≤C5 alkynes and more resistant to longer-chain length alkynes. Reproducible differences were observed among N. maritimus, N. viennensis, and N. gargensis in regard to the extent of their resistance/sensitivity to C6 and C7 1-alkynes, which may indicate differences in the ammonia monooxygenase binding and catalytic site(s) among the Thaumarchaeota. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  15. Reduction of nitrogen oxides with catalytic acid resistant aluminosilicate molecular sieves and ammonia

    DOEpatents

    Pence, Dallas T.; Thomas, Thomas R.

    1980-01-01

    Noxious nitrogen oxides in a waste gas stream such as the stack gas from a fossil-fuel-fired power generation plant or other industrial plant off-gas stream is catalytically reduced to elemental nitrogen and/or innocuous nitrogen oxides employing ammonia as reductant in the presence of a zeolite catalyst in the hydrogen or sodium form having pore openings of about 3 to 10 A.

  16. Dynamics of ammonia-oxidizing communities in barley-planted bulk soil and rhizosphere following nitrate and ammonium fertilizer amendment.

    PubMed

    Glaser, Katrin; Hackl, Evelyn; Inselsbacher, Erich; Strauss, Joseph; Wanek, Wolfgang; Zechmeister-Boltenstern, Sophie; Sessitsch, Angela

    2010-12-01

    Oxidation of ammonia by nitrifying microorganisms is a major pathway that fertilizer nitrogen (N) may take upon application to agricultural soils, but the relative roles of bacterial (AOB) vs. archaeal (AOA) ammonia oxidizers are controversial. We explored the effects of various forms of mineral N fertilizer on the AOB and AOA community dynamics in two different soils planted with barley. Ammonia oxidizers were monitored via real-time PCR and terminal restriction fragment length polymorphism analysis of bacterial and archaeal amoA genes following the addition of either [NH₄]₂SO₄, NH₄NO₃ or KNO₃. AOB and AOA communities were also studied specifically in the rhizospheres of two different barley varieties upon [NH₄]₂SO₄ vs. KNO₃ addition. AOB changed in community composition and increased in abundance upon ammonium amendment in bulk soil and rhizosphere, with changes in bacterial amoA copy numbers lagging behind relative to changes in soil ammonium. In both soils, only T-RFs corresponding to phylotypes related to Nitrosospira clade 3a underwent significant community changes. Increases in AOB abundance were generally stronger in the bulk soil than in the rhizosphere, implying significant ammonia uptake by plant roots. AOA underwent shifts in the community composition over time and fluctuated in abundance in all treatments irrespective of ammonia availability. AOB were thus considered as the main agents responsible for fertilizer ammonium oxidation, while the functions of AOA in soil N cycling remain unresolved. © 2010 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  17. Resveratrol Prevents Ammonia Toxicity in Astroglial Cells

    PubMed Central

    Guerra, Maria Cristina; Leite, Marina Concli; Souza, Diogo Onofre; Gonçalves, Carlos-Alberto; Gottfried, Carmem

    2012-01-01

    Ammonia is implicated as a neurotoxin in brain metabolic disorders associated with hyperammonemia. Acute ammonia toxicity can be mediated by an excitotoxic mechanism, oxidative stress and nitric oxide (NO) production. Astrocytes interact with neurons, providing metabolic support and protecting against oxidative stress and excitotoxicity. Astrocytes also convert excess ammonia and glutamate into glutamine via glutamine synthetase (GS). Resveratrol, a polyphenol found in grapes and red wines, exhibits antioxidant and anti-inflammatory properties and modulates glial functions, such as glutamate metabolism. We investigated the effect of resveratrol on the production of reactive oxygen species (ROS), GS activity, S100B secretion, TNF-α, IL-1β and IL-6 levels in astroglial cells exposed to ammonia. Ammonia induced oxidative stress, decreased GS activity and increased cytokines release, probably by a mechanism dependent on protein kinase A (PKA) and extracellular signal-regulated kinase (ERK) pathways. Resveratrol prevented ammonia toxicity by modulating oxidative stress, glial and inflammatory responses. The ERK and nuclear factor-κB (NF-κB) are involved in the protective effect of resveratrol on cytokines proinflammatory release. In contrast, other antioxidants (e.g., ascorbic acid and trolox) were not effective against hyperammonemia. Thus, resveratrol could be used to protect against ammonia-induced neurotoxicity. PMID:23284918

  18. Azobisisobutyronitrile initiated aerobic oxidative transformation of amines: coupling of primary amines and cyanation of tertiary amines.

    PubMed

    Liu, Lianghui; Wang, Zikuan; Fu, Xuefeng; Yan, Chun-Hua

    2012-11-16

    In the presence of a catalytic amount of radical initiator AIBN, primary amines are oxidatively coupled to imines and tertiary amines are cyanated to α-aminonitriles. These "metal-free" aerobic oxidative coupling reactions may find applications in a wide range of "green" oxidation chemistry.

  19. Diversity surveys and evolutionary relationships of aoxB genes in aerobic arsenite-oxidizing bacteria.

    PubMed

    Quéméneur, Marianne; Heinrich-Salmeron, Audrey; Muller, Daniel; Lièvremont, Didier; Jauzein, Michel; Bertin, Philippe N; Garrido, Francis; Joulian, Catherine

    2008-07-01

    A new primer set was designed to specifically amplify ca. 1,100 bp of aoxB genes encoding the As(III) oxidase catalytic subunit from taxonomically diverse aerobic As(III)-oxidizing bacteria. Comparative analysis of AoxB protein sequences showed variable conservation levels and highlighted the conservation of essential amino acids and structural motifs. AoxB phylogeny of pure strains showed well-discriminated taxonomic groups and was similar to 16S rRNA phylogeny. Alphaproteobacteria-, Betaproteobacteria-, and Gammaproteobacteria-related sequences were retrieved from environmental surveys, demonstrating their prevalence in mesophilic As-contaminated soils. Our study underlines the usefulness of the aoxB gene as a functional marker of aerobic As(III) oxidizers.

  20. Effect of Toxic Metals on Indigenous Soil β-Subgroup Proteobacterium Ammonia Oxidizer Community Structure and Protection against Toxicity by Inoculated Metal-Resistant Bacteria

    PubMed Central

    Stephen, John R.; Chang, Yun-Juan; Macnaughton, Sarah J.; Kowalchuk, George A.; Leung, Kam T.; Flemming, Cissy A.; White, David C.

    1999-01-01

    Contamination of soils with toxic metals is a major problem on military, industrial, and mining sites worldwide. Of particular interest to the field of bioremediation is the selection of biological markers for the end point of remediation. In this microcosm study, we focus on the effect of addition of a mixture of toxic metals (cadmium, cobalt, cesium, and strontium as chlorides) to soil on the population structure and size of the ammonia oxidizers that are members of the beta subgroup of the Proteobacteria (β-subgroup ammonia oxidizers). In a parallel experiment, the soils were also treated by the addition of five strains of metal-resistant heterotrophic bacteria. Effects on nitrogen cycling were measured by monitoring the NH3 and NH4+ levels in soil samples. The gene encoding the α-subunit of ammonia monooxygenase (amoA) was selected as a functional molecular marker for the β-subgroup ammonia oxidizing bacteria. Community structure comparisons were performed with clone libraries of PCR-amplified fragments of amoA recovered from contaminated and control microcosms for 8 weeks. Analysis was performed by restriction digestion and sequence comparison. The abundance of ammonia oxidizers in these microcosms was also monitored by competitive PCR. All amoA gene fragments recovered grouped with sequences derived from cultured Nitrosospira. These comprised four novel sequence clusters and a single unique clone. Specific changes in the community structure of β-subgroup ammonia oxidizers were associated with the addition of metals. These changes were not seen in the presence of the inoculated metal-resistant bacteria. Neither treatment significantly altered the total number of β-subgroup ammonia-oxidizing cells per gram of soil compared to untreated controls. Following an initial decrease in concentration, ammonia began to accumulate in metal-treated soils toward the end of the experiment. PMID:9872765

  1. Review of Options for Ammonia/Ammonium Management

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Nash, C. A.

    This report is a review of literature supporting practical ammonia/ammonium destruction processes. Melter research supporting Hanford Low Activity Waste (LAW) glass production has shown that significant amounts of ammonia will be in the melter offgas condensate. Further work with secondary waste forms indicates the potential need to remove the ammonia, perhaps by an oxidative process. This review finds likely practical chemical methods to oxidize ammonia in aqueous solution at moderate temperatures and atmospheric pressure, using easily obtained reagents. Leading candidates include nitrite oxidation to produce nitrogen gas, various peroxide oxidative processes, and air stripping. This work reviews many other processesmore » and provides reasoning to not consider those processes further for this application.« less

  2. Surface Structure of Aerobically Oxidized Diamond Nanocrystals

    DOE PAGES

    Wolcott, Abraham; Schiros, Theanne; Trusheim, Matthew E.; ...

    2014-10-27

    Here we investigate the aerobic oxidation of high-pressure, high-temperature nanodiamonds (5–50 nm dimensions) using a combination of carbon and oxygen K-edge X-ray absorption, wavelength-dependent X-ray photoelectron, and vibrational spectroscopies. Oxidation at 575 °C for 2 h eliminates graphitic carbon contamination (>98%) and produces nanocrystals with hydroxyl functionalized surfaces as well as a minor component (<5%) of carboxylic anhydrides. The low graphitic carbon content and the high crystallinity of HPHT are evident from Raman spectra acquired using visible wavelength excitation (λ excit = 633 nm) as well as carbon K-edge X-ray absorption spectra where the signature of a core–hole exciton ismore » observed. Both spectroscopic features are similar to those of chemical vapor deposited (CVD) diamond but differ significantly from the spectra of detonation nanodiamond. Lastly, we discuss the importance of these findings to the functionalization of nanodiamond surfaces for biological labeling applications.« less

  3. Surface Structure of Aerobically Oxidized Diamond Nanocrystals

    PubMed Central

    2015-01-01

    We investigate the aerobic oxidation of high-pressure, high-temperature nanodiamonds (5–50 nm dimensions) using a combination of carbon and oxygen K-edge X-ray absorption, wavelength-dependent X-ray photoelectron, and vibrational spectroscopies. Oxidation at 575 °C for 2 h eliminates graphitic carbon contamination (>98%) and produces nanocrystals with hydroxyl functionalized surfaces as well as a minor component (<5%) of carboxylic anhydrides. The low graphitic carbon content and the high crystallinity of HPHT are evident from Raman spectra acquired using visible wavelength excitation (λexcit = 633 nm) as well as carbon K-edge X-ray absorption spectra where the signature of a core–hole exciton is observed. Both spectroscopic features are similar to those of chemical vapor deposited (CVD) diamond but differ significantly from the spectra of detonation nanodiamond. The importance of these findings to the functionalization of nanodiamond surfaces for biological labeling applications is discussed. PMID:25436035

  4. Freshwater Recirculating Aquaculture System Operations Drive Biofilter Bacterial Community Shifts around a Stable Nitrifying Consortium of Ammonia-Oxidizing Archaea and Comammox Nitrospira

    PubMed Central

    Bartelme, Ryan P.; McLellan, Sandra L.; Newton, Ryan J.

    2017-01-01

    Recirculating aquaculture systems (RAS) are unique engineered ecosystems that minimize environmental perturbation by reducing nutrient pollution discharge. RAS typically employ a biofilter to control ammonia levels produced as a byproduct of fish protein catabolism. Nitrosomonas (ammonia-oxidizing), Nitrospira, and Nitrobacter (nitrite-oxidizing) species are thought to be the primary nitrifiers present in RAS biofilters. We explored this assertion by characterizing the biofilter bacterial and archaeal community of a commercial scale freshwater RAS that has been in operation for >15 years. We found the biofilter community harbored a diverse array of bacterial taxa (>1000 genus-level taxon assignments) dominated by Chitinophagaceae (~12%) and Acidobacteria (~9%). The bacterial community exhibited significant composition shifts with changes in biofilter depth and in conjunction with operational changes across a fish rearing cycle. Archaea also were abundant, and were comprised solely of a low diversity assemblage of Thaumarchaeota (>95%), thought to be ammonia-oxidizing archaea (AOA) from the presence of AOA ammonia monooxygenase genes. Nitrosomonas were present at all depths and time points. However, their abundance was >3 orders of magnitude less than AOA and exhibited significant depth-time variability not observed for AOA. Phylogenetic analysis of the nitrite oxidoreductase beta subunit (nxrB) gene indicated two distinct Nitrospira populations were present, while Nitrobacter were not detected. Subsequent identification of Nitrospira ammonia monooxygenase alpha subunit genes in conjunction with the phylogenetic placement and quantification of the nxrB genotypes suggests complete ammonia-oxidizing (comammox) and nitrite-oxidizing Nitrospira populations co-exist with relatively equivalent and stable abundances in this system. It appears RAS biofilters harbor complex microbial communities whose composition can be affected directly by typical system operations while

  5. Microbiology and potential applications of aerobic methane oxidation coupled to denitrification (AME-D) process: A review.

    PubMed

    Zhu, Jing; Wang, Qian; Yuan, Mengdong; Tan, Giin-Yu Amy; Sun, Faqian; Wang, Cheng; Wu, Weixiang; Lee, Po-Heng

    2016-03-01

    Aerobic methane oxidation coupled to denitrification (AME-D) is an important link between the global methane and nitrogen cycles. This mini-review updates discoveries regarding aerobic methanotrophs and denitrifiers, as a prelude to spotlight the microbial mechanism and the potential applications of AME-D. Until recently, AME-D was thought to be accomplished by a microbial consortium where denitrifying bacteria utilize carbon intermediates, which are excreted by aerobic methanotrophs, as energy and carbon sources. Potential carbon intermediates include methanol, citrate and acetate. This mini-review presents microbial thermodynamic estimations and postulates that methanol is the ideal electron donor for denitrification, and may serve as a trophic link between methanotrophic bacteria and denitrifiers. More excitingly, new discoveries have revealed that AME-D is not only confined to the conventional synergism between methanotrophic bacteria and denitrifiers. Specifically, an obligate aerobic methanotrophic bacterium, Methylomonas denitrificans FJG1, has been demonstrated to couple partial denitrification with methane oxidation, under hypoxia conditions, releasing nitrous oxide as a terminal product. This finding not only substantially advances the understanding of AME-D mechanism, but also implies an important but unknown role of aerobic methanotrophs in global climate change through their influence on both the methane and nitrogen cycles in ecosystems. Hence, further investigation on AME-D microbiology and mechanism is essential to better understand global climate issues and to develop niche biotechnological solutions. This mini-review also presents traditional microbial techniques, such as pure cultivation and stable isotope probing, and powerful microbial techniques, such as (meta-) genomics and (meta-) transcriptomics, for deciphering linked methane oxidation and denitrification. Although AME-D has immense potential for nitrogen removal from wastewater, drinking

  6. Moisture and temperature controls on nitrification differ among ammonia oxidizer communities from three alpine soil habitats

    NASA Astrophysics Data System (ADS)

    Osborne, Brooke B.; Baron, Jill S.; Wallenstein, Matthew D.

    2016-03-01

    Climate change is altering the timing and magnitude of biogeochemical fluxes in many highelevation ecosystems. The consequent changes in alpine nitrification rates have the potential to influence ecosystem scale responses. In order to better understand how changing temperature and moisture conditions may influence ammonia oxidizers and nitrification activity, we conducted laboratory incubations on soils collected in a Colorado watershed from three alpine habitats (glacial outwash, talus, and meadow). We found that bacteria, not archaea, dominated all ammonia oxidizer communities. Nitrification increased with moisture in all soils and under all temperature treatments. However, temperature was not correlated with nitrification rates in all soils. Site-specific temperature trends suggest the development of generalist ammonia oxidzer communities in soils with greater in situ temperature fluctuations and specialists in soils with more steady temperature regimes. Rapidly increasing temperatures and changing soil moisture conditions could explain recent observations of increased nitrate production in some alpine soils.

  7. Ammonia concentration determines differential growth of ammonia-oxidising archaea and bacteria in soil microcosms.

    PubMed

    Verhamme, Daniel T; Prosser, James I; Nicol, Graeme W

    2011-06-01

    The first step of nitrification, oxidation of ammonia to nitrite, is performed by both ammonia-oxidising archaea (AOA) and ammonia-oxidising bacteria (AOB) in soil, but their relative contributions to ammonia oxidation and existence in distinct ecological niches remain to be determined. To determine whether available ammonia concentration has a differential effect on AOA and AOB growth, soil microcosms were incubated for 28 days with ammonium at three concentrations: native (control), intermediate (20 μg NH(4)(+)-N per gram of soil) and high (200 μg NH(4)(+)-N per gram of soil). Quantitative PCR demonstrated growth of AOA at all concentrations, whereas AOB growth was prominent only at the highest concentration. Similarly, denaturing gradient gel electrophoresis (DGGE) analysis revealed changes in AOA communities at all ammonium concentrations, whereas AOB communities changed significantly only at the highest ammonium concentration. These results provide evidence that ammonia concentration contributes to the definition of distinct ecological niches of AOA and AOB in soil.

  8. Ammonia concentration determines differential growth of ammonia-oxidising archaea and bacteria in soil microcosms

    PubMed Central

    Verhamme, Daniel T; Prosser, James I; Nicol, Graeme W

    2011-01-01

    The first step of nitrification, oxidation of ammonia to nitrite, is performed by both ammonia-oxidising archaea (AOA) and ammonia-oxidising bacteria (AOB) in soil, but their relative contributions to ammonia oxidation and existence in distinct ecological niches remain to be determined. To determine whether available ammonia concentration has a differential effect on AOA and AOB growth, soil microcosms were incubated for 28 days with ammonium at three concentrations: native (control), intermediate (20 μg NH4+-N per gram of soil) and high (200 μg NH4+-N per gram of soil). Quantitative PCR demonstrated growth of AOA at all concentrations, whereas AOB growth was prominent only at the highest concentration. Similarly, denaturing gradient gel electrophoresis (DGGE) analysis revealed changes in AOA communities at all ammonium concentrations, whereas AOB communities changed significantly only at the highest ammonium concentration. These results provide evidence that ammonia concentration contributes to the definition of distinct ecological niches of AOA and AOB in soil. PMID:21228892

  9. Ammonia-induced oxidative damage in neurons is prevented by resveratrol and lipoic acid with participation of heme oxygenase 1.

    PubMed

    Bobermin, Larissa Daniele; Wartchow, Krista Minéia; Flores, Marianne Pires; Leite, Marina Concli; Quincozes-Santos, André; Gonçalves, Carlos-Alberto

    2015-07-01

    Ammonia is a metabolite that, at high concentrations, is implicated in neurological disorders, such as hepatic encephalopathy (HE), which is associated with acute or chronic liver failure. Astrocytes are considered the primary target of ammonia toxicity in the central nervous system (CNS) because glutamine synthetase (GS), responsible for ammonia metabolism in CNS, is an astrocytic enzyme. Thus, neuronal dysfunction has been associated as secondary to astrocytic impairment. However, we demonstrated that ammonia can induce direct effects on neuronal cells. The cell viability was decreased by ammonia in SH-SY5Y cells and cerebellar granule neurons. In addition, ammonia induced increased reactive oxygen species (ROS) production and decreased GSH intracellular content, the main antioxidant in CNS. As ammonia neurotoxicity is strongly associated with oxidative stress, we also investigated the potential neuroprotective roles of the antioxidants, resveratrol (RSV) and lipoic acid (LA), against ammonia toxicity in cerebellar granule neurons. RSV and LA were able to prevent the oxidative damage induced by ammonia, maintaining the levels of ROS production and GSH close to basal values. Both antioxidants also decreased ROS production and increased GSH content under basal conditions (in the absence of ammonia). Moreover, we showed that heme oxygenase 1 (HO1), a protein associated with protection against stress conditions, is involved in the beneficial effects of RSV and LA in cerebellar granule neurons. Thus, this study reinforces the neuroprotective effects of RSV and LA. Although more studies in vivo are required, RSV and LA could represent interesting therapeutic strategies for the management of HE. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. [Impact of periodical flooding-drying on nitrification and ammonia oxidizers in hydro-fluctuation belt of the Three Gorges Reservoir].

    PubMed

    Guo, Jia; Jiang, Xianjun; Zhou, Xue; Meng, Yao; Jia, Zhongjun

    2016-06-04

    This study was aimed to elucidate the effect of periodic flooding-drying to ecological processes of ammonia oxidizers in the hydro-fluctuation belt of the Three Gorges Reservoir. Soil samples were collected at thee altitudes in regions of Wanzhou, Fengdu and Changshou, representing 8, 5 and 0 times floodingdrying management, respectively. Soil physiochemical properties were analyzed and microcosms were constructed to monitor nitrification activity by fertilizing soils with ammonium substrate. Real-time PCR was used to quantify the population size of ammonia-oxidizing archaea (AOA) and bacteria (AOB). DGGE fingerprints and clone libraries were conducted to study the shift of AOA and AOB compositions in nitrifying soils. Among the physiochemical characteristics of the soils, soil organic matter and total phosphates increased along with cycle increasing. After incubation for 13 days, the net nitrification rates of the samples with 8 cycles exceeded those with 5 cycles. The quantities of both AOA and AOB have increased during the incubation. Phylogenetic analysis showed that AOA were placed within the soil group 1.1b and soil group 1.1a, while bacterial ammonia oxidizers were closely related to Nitrosospira and Cluster 0. Periodical flooding-drying increased soil organic matter, enhanced soil nitrification activity and likely played important roles in shaping community structures of soil ammonia oxidizers.

  11. Thermodynamics of dissolved nitrogen, nitrous oxide, and ammonia in perfluorodecalin

    NASA Astrophysics Data System (ADS)

    Moshnyaga, A. V.; Khoroshilov, A. V.; Selivanova, D. I.; Aksenova, D. M.

    2017-11-01

    The solubility of N2, N2O, and NH3 is studied in different organic solvents. The best dissolution (0.27 ppm) is found to be for N2O in perfluorodecalin at 291 K and a pressure of 99 kPa. The dependence of N2O solubility in perfluorodecalin on pressure is studied at 291 K. The Gibbs energy of the solubility of nitrogen, nitrous oxide, and ammonia in perfluorodecalin is calculated.

  12. Identification of key nitrous oxide production pathways in aerobic partial nitrifying granules.

    PubMed

    Ishii, Satoshi; Song, Yanjun; Rathnayake, Lashitha; Tumendelger, Azzaya; Satoh, Hisashi; Toyoda, Sakae; Yoshida, Naohiro; Okabe, Satoshi

    2014-10-01

    The identification of the key nitrous oxide (N2O) production pathways is important to establish a strategy to mitigate N2O emission. In this study, we combined real-time gas-monitoring analysis, (15)N stable isotope analysis, denitrification functional gene transcriptome analysis and microscale N2O concentration measurements to identify the main N2O producers in a partial nitrification (PN) aerobic granule reactor, which was fed with ammonium and acetate. Our results suggest that heterotrophic denitrification was the main contributor to N2O production in our PN aerobic granule reactor. The heterotrophic denitrifiers were probably related to Rhodocyclales bacteria, although different types of bacteria were active in the initial and latter stages of the PN reaction cycles, most likely in response to the presence of acetate. Hydroxylamine oxidation and nitrifier denitrification occurred, but their contribution to N2O emission was relatively small (20-30%) compared with heterotrophic denitrification. Our approach can be useful to quantitatively examine the relative contributions of the three pathways (hydroxylamine oxidation, nitrifier denitrification and heterotrophic denitrification) to N2O emission in mixed microbial populations. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.

  13. Enhanced and selective ammonia sensing of reduced graphene oxide based chemo resistive sensor at room temperature

    NASA Astrophysics Data System (ADS)

    Kumar, Ramesh; Kaur, Amarjeet

    2016-05-01

    The reduced graphene oxide thin films were fabricated by using the spin coating method. The reduced graphene oxide samples were characterised by Raman studies to obtain corresponding D and G bands at 1360 and 1590 cm-1 respectively. Fourier transform infra-red (FTIR) spectra consists of peak corresponds to sp2 hybridisation of carbon atoms at 1560 cm-1. The reduced graphene oxide based chemoresistive sensor exhibited a p-type semiconductor behaviour in ambient conditions and showed good sensitivity to different concentration of ammonia from 25 ppm to 500 ppm and excellent selectivity at room temperature. The sensor displays selectivity to several hazardous vapours such as methanol, ethanol, acetone and hydrazine hydrate. The sensor demonstrated a sensitivity of 9.8 at 25 ppm concentration of ammonia with response time of 163 seconds.

  14. Synergistic Effect of Mixed Oxide on the Adsorption of Ammonia with Metal–Organic Frameworks

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mounfield, III, William P.; Taborga Claure, Micaela; Agrawal, Pradeep K.

    A hydrotalcite-derived MgAl oxide (MMO) was evaluated in combination with the metal–organic frameworks (MOFs) UiO-66 and UiO-66-NH 2 for the adsorption of ammonia. Analysis of the materials’ textural properties after ammonia breakthrough adsorption revealed no change in the PXRD patterns or FTIR spectra; however, a slight decrease in surface area was observed, consistent with the hypothesized presence of strongly adsorbed species after adsorption. UiO-66:MMO and UiO-66-NH 2:MMO composites maintained ammonia adsorption capacity under dry conditions. An almost 2-fold increase in humid ammonia capacity was observed for the UiO-66:MMO composite, far beyond that expected through a linear combination of the twomore » materials’ capacities. As a result, the synergistic effect observed in humid conditions was further investigated with water adsorption experiments, which suggested the effect is the result of the high water affinity of MMO.« less

  15. Synergistic Effect of Mixed Oxide on the Adsorption of Ammonia with Metal–Organic Frameworks

    DOE PAGES

    Mounfield, III, William P.; Taborga Claure, Micaela; Agrawal, Pradeep K.; ...

    2016-06-08

    A hydrotalcite-derived MgAl oxide (MMO) was evaluated in combination with the metal–organic frameworks (MOFs) UiO-66 and UiO-66-NH 2 for the adsorption of ammonia. Analysis of the materials’ textural properties after ammonia breakthrough adsorption revealed no change in the PXRD patterns or FTIR spectra; however, a slight decrease in surface area was observed, consistent with the hypothesized presence of strongly adsorbed species after adsorption. UiO-66:MMO and UiO-66-NH 2:MMO composites maintained ammonia adsorption capacity under dry conditions. An almost 2-fold increase in humid ammonia capacity was observed for the UiO-66:MMO composite, far beyond that expected through a linear combination of the twomore » materials’ capacities. As a result, the synergistic effect observed in humid conditions was further investigated with water adsorption experiments, which suggested the effect is the result of the high water affinity of MMO.« less

  16. Cultivation of a highly enriched ammonia-oxidizing archaeon of thaumarchaeotal group I.1b from an agricultural soil.

    PubMed

    Kim, Jong-Geol; Jung, Man-Young; Park, Soo-Je; Rijpstra, W Irene C; Sinninghe Damsté, Jaap S; Madsen, Eugene L; Min, Deullae; Kim, Jin-Seog; Kim, Geun-Joong; Rhee, Sung-Keun

    2012-06-01

    Nitrification of excess ammonia in soil causes eutrophication of water resources and emission of atmospheric N(2) O gas. The first step of nitrification, ammonia oxidation, is mediated by Archaea as well as Bacteria. The physiological reactions mediated by ammonia-oxidizing archaea (AOA) and their contribution to soil nitrification are still unclear. Results of non-culture-based studies have shown the thaumarchaeotal group I.1b lineage of AOA to be dominant over both AOA of group I.1a and ammonia-oxidizing bacteria in various soils. We obtained from an agricultural soil a highly enriched ammonia-oxidizing culture dominated by a single archaeal population [c. 90% of total cells, as determined microscopically (by fluorescence in situ hybridization) and by quantitative PCR of its 16S rRNA gene]. The archaeon (termed 'strain JG1') fell within thaumarchaeotal group I.1b and was related to the moderately thermophilic archaeon, Candidatus Nitrososphaera gargensis, and the mesophilic archaeon, Ca. Nitrososphaera viennensis with 97.0% and 99.1% 16S rRNA gene sequence similarity respectively. Strain JG1 was neutrophilic (growth range pH 6.0-8.0) and mesophilic (growth range temperature 25-40°C). The optimum temperature of strain JG1 (35-40°C) is > 10°C higher than that of ammonia-oxidizing bacteria (AOB). Membrane analysis showed that strain JG1 contained a glycerol dialkyl glycerol tetraether, GDGT-4, and its regioisomer as major core lipids; this crenarchaeol regioisomer was previously detected in similar abundance in the thermophile, Ca. N. gargensis and has been frequently observed in tropical soils. Substrate uptake assays showed that the affinity of strain JG1 for ammonia and oxygen was much higher than those of AOB. These traits may give a competitive advantage to AOA related to strain JG1 in oligotrophic environments. (13) C-bicarbonate incorporation into archaeal lipids of strain JG1 established its ability to grow autotrophically. Strain JG1 produced a

  17. Aerobic oxidation of alcohols in visible light on Pd-grafted Ti cluster

    EPA Pesticide Factsheets

    The titanium cluster with the reduced band gap has been synthesized having the palladium nanoparticles over the surface, which not only binds to the atmospheric oxygen but also catalyzes the oxidation of alcohols under visible light.This dataset is associated with the following publication:Varma, R., M. Nadagouda, S. Verma, and R.B.N. Baig. Aerobic oxidation of alcohols in visible light on Pd-grafted Ti cluster. TETRAHEDRON. Elsevier Science Ltd, New York, NY, USA, (2016).

  18. Impacts of Edaphic Factors on Communities of Ammonia-Oxidizing Archaea, Ammonia-Oxidizing Bacteria and Nitrification in Tropical Soils

    PubMed Central

    de Gannes, Vidya; Eudoxie, Gaius; Hickey, William J.

    2014-01-01

    Nitrification is a key process in soil nitrogen (N) dynamics, but relatively little is known about it in tropical soils. In this study, we examined soils from Trinidad to determine the edaphic drivers affecting nitrification levels and community structure of ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) in non-managed soils. The soils were naturally vegetated, ranged in texture from sands to clays and spanned pH 4 to 8. The AOA were detected by qPCR in all soils (ca. 105 to 106 copies archaeal amoA g−1 soil), but AOB levels were low and bacterial amoA was infrequently detected. AOA abundance showed a significant negative correlation (p<0.001) with levels of soil organic carbon, clay and ammonium, but was not correlated to pH. Structures of AOA and AOB communities, as determined by amoA terminal restriction fragment (TRF) analysis, differed significantly between soils (p<0.001). Variation in AOA TRF profiles was best explained by ammonium-N and either Kjeldahl N or total N (p<0.001) while variation in AOB TRF profiles was best explained by phosphorus, bulk density and iron (p<0.01). In clone libraries, phylotypes of archaeal amoA (predominantly Nitrososphaera) and bacterial amoA (predominanatly Nitrosospira) differed between soils, but variation was not correlated with pH. Nitrification potential was positively correlated with clay content and pH (p<0.001), but not to AOA or AOB abundance or community structure. Collectively, the study showed that AOA and AOB communities were affected by differing sets of edaphic factors, notably that soil N characteristics were significant for AOA, but not AOB, and that pH was not a major driver for either community. Thus, the effect of pH on nitrification appeared to mainly reflect impacts on AOA or AOB activity, rather than selection for AOA or AOB phylotypes differing in nitrifying capacity. PMID:24586878

  19. The effect of human settlement on the abundance and community structure of ammonia oxidizers in tropical stream sediments

    PubMed Central

    Reis, Mariana P.; Ávila, Marcelo P.; Keijzer, Rosalinde M.; Barbosa, Francisco A. R.; Chartone-Souza, Edmar; Nascimento, Andréa M. A.; Laanbroek, Hendrikus J.

    2015-01-01

    Ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) are a diverse and functionally important group in the nitrogen cycle. Nevertheless, AOA and AOB communities driving this process remain uncharacterized in tropical freshwater sediment. Here, the effect of human settlement on the AOA and AOB diversity and abundance have been assessed by phylogenetic and quantitative PCR analyses, using archaeal and bacterial amoA and 16S rRNA genes. Overall, each environment contained specific clades of amoA and 16S rRNA genes sequences, suggesting that selective pressures lead to AOA and AOB inhabiting distinct ecological niches. Human settlement activities, as derived from increased metal and mineral nitrogen contents, appear to cause a response among the AOB community, with Nitrosomonas taking advantage over Nitrosospira in impacted environments. We also observed a dominance of AOB over AOA in mining-impacted sediments, suggesting that AOB might be the primary drivers of ammonia oxidation in these sediments. In addition, ammonia concentrations demonstrated to be the driver for the abundance of AOA, with an inversely proportional correlation between them. Our findings also revealed the presence of novel ecotypes of Thaumarchaeota, such as those related to the obligate acidophilic Nitrosotalea devanaterra at ammonia-rich places of circumneutral pH. These data add significant new information regarding AOA and AOB from tropical freshwater sediments, albeit future studies would be required to provide additional insights into the niche differentiation among these microorganisms. PMID:26379659

  20. Inhabitancy of active Nitrosopumilus-like ammonia-oxidizing archaea and Nitrospira nitrite-oxidizing bacteria in the sponge Theonella swinhoei

    PubMed Central

    Feng, Guofang; Sun, Wei; Zhang, Fengli; Karthik, Loganathan; Li, Zhiyong

    2016-01-01

    Nitrification directly contributes to the ammonia removal in sponges, and it plays an indispensable role in sponge-mediated nitrogen cycle. Previous studies have demonstrated genomic evidences of nitrifying lineages in the sponge Theonella swinhoei. However, little is known about the transcriptional activity of nitrifying community in this sponge. In this study, combined DNA- and transcript-based analyses were performed to reveal the composition and transcriptional activity of the nitrifiers in T. swinhoei from the South China Sea. Transcriptional activity of ammonia-oxidizing archaea (AOA) and nitrite-oxidizing bacteria (NOB) in this sponge were confirmed by targeting their nitrifying genes,16S rRNA genes and their transcripts. Phylogenetic analysis coupled with RDP rRNA classification indicated that archaeal 16S rRNA genes, amoA (the subunit of ammonia monooxygenase) genes and their transcripts were closely related to Nitrosopumilus-like AOA; whereas nitrifying bacterial 16S rRNA genes, nxrB (the subunit of nitrite oxidoreductase) genes and their transcripts were closely related to Nitrospira NOB. Quantitative assessment demonstrated relative higher abundances of nitrifying genes and transcripts of Nitrosopumilus-like AOA than those of Nitrospira NOB in this sponge. This study illustrated the transcriptional potentials of Nitrosopumilus-like archaea and Nitrospira bacteria that would predominantly contribute to the nitrification functionality in the South China Sea T. swinhoei. PMID:27113140

  1. Continuous-flow synthesis of functionalized phenols by aerobic oxidation of Grignard reagents.

    PubMed

    He, Zhi; Jamison, Timothy F

    2014-03-24

    Phenols are important compounds in chemical industry. An economical and green approach to phenol preparation by the direct oxidation of aryl Grignard reagents using compressed air in continuous gas-liquid segmented flow systems is described. The process tolerates a broad range of functional groups, including oxidation-sensitive functionalities such as alkenes, amines, and thioethers. By integrating a benzyne-mediated in-line generation of arylmagnesium intermediates with the aerobic oxidation, a facile three-step, one-flow process, capable of preparing 2-functionalized phenols in a modular fashion, is established. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Ammonia- and nitrite-oxidizing bacterial communities in a pilot-scale chloraminated drinking water distribution system.

    PubMed

    Regan, John M; Harrington, Gregory W; Noguera, Daniel R

    2002-01-01

    Nitrification in drinking water distribution systems is a common operational problem for many utilities that use chloramines for secondary disinfection. The diversity of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) in the distribution systems of a pilot-scale chloraminated drinking water treatment system was characterized using terminal restriction fragment length polymorphism (T-RFLP) analysis and 16S rRNA gene (ribosomal DNA [rDNA]) cloning and sequencing. For ammonia oxidizers, 16S rDNA-targeted T-RFLP indicated the presence of Nitrosomonas in each of the distribution systems, with a considerably smaller peak attributable to Nitrosospira-like AOB. Sequences of AOB amplification products aligned within the Nitrosomonas oligotropha cluster and were closely related to N. oligotropha and Nitrosomonas ureae. The nitrite-oxidizing communities were comprised primarily of Nitrospira, although Nitrobacter was detected in some samples. These results suggest a possible selection of AOB related to N. oligotropha and N. ureae in chloraminated systems and demonstrate the presence of NOB, indicating a biological mechanism for nitrite loss that contributes to a reduction in nitrite-associated chloramine decay.

  3. Ammonia- and Nitrite-Oxidizing Bacterial Communities in a Pilot-Scale Chloraminated Drinking Water Distribution System

    PubMed Central

    Regan, John M.; Harrington, Gregory W.; Noguera, Daniel R.

    2002-01-01

    Nitrification in drinking water distribution systems is a common operational problem for many utilities that use chloramines for secondary disinfection. The diversity of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) in the distribution systems of a pilot-scale chloraminated drinking water treatment system was characterized using terminal restriction fragment length polymorphism (T-RFLP) analysis and 16S rRNA gene (ribosomal DNA [rDNA]) cloning and sequencing. For ammonia oxidizers, 16S rDNA-targeted T-RFLP indicated the presence of Nitrosomonas in each of the distribution systems, with a considerably smaller peak attributable to Nitrosospira-like AOB. Sequences of AOB amplification products aligned within the Nitrosomonas oligotropha cluster and were closely related to N. oligotropha and Nitrosomonas ureae. The nitrite-oxidizing communities were comprised primarily of Nitrospira, although Nitrobacter was detected in some samples. These results suggest a possible selection of AOB related to N. oligotropha and N. ureae in chloraminated systems and demonstrate the presence of NOB, indicating a biological mechanism for nitrite loss that contributes to a reduction in nitrite-associated chloramine decay. PMID:11772611

  4. Impact of Heavy Metal Pollution on Ammonia Oxidizers in Soils in the Vicinity of a Tailings Dam, Baotou, China.

    PubMed

    Liu, Jumei; Cao, Weiwei; Jiang, Haiming; Cui, Jing; Shi, Chunfang; Qiao, Xiaohui; Zhao, Ji; Si, Wantong

    2018-05-09

    Soil heavy metal pollution has received increasing attention due to their toxicity to soil microorganisms. We have analyzed the effects of heavy metal pollution on ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in soils in the vicinity of a tailings dam of Baotou region, China. Results showed that AOB were dominated with Nitrosomonas-like clusters, while AOA was dominated by group1.1b (Nitrososphaera cluster). Single Cd and Cr contents, as well as compound heavy metal pollution levels, had a significant negative impact on soil potential nitrification rate and both diversities of AOA and AOB. No clear relationship was found between any single heavy metal and abundance of AOA or AOB. But compound pollution could significantly decrease AOA abundance. The results indicated that heavy metal pollution had an obviously deleterious effect on the abundance, diversity, activity and composition of ammonia oxidizers in natural soils.

  5. Niche specificity of ammonia-oxidizing archaeal and bacterial communities in a freshwater wetland receiving municipal wastewater in Daqing, Northeast China.

    PubMed

    Lee, Kwok-Ho; Wang, Yong-Feng; Li, Hui; Gu, Ji-Dong

    2014-12-01

    Ecophysiological differences between ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) enable them to adapt to different niches in complex freshwater wetland ecosystems. The community characters of AOA and AOB in the different niches in a freshwater wetland receiving municipal wastewater, as well as the physicochemical parameters of sediment/soil samples, were investigated in this study. AOA community structures varied and separated from each other among four different niches. Wetland vegetation including aquatic macrophytes and terrestrial plants affected the AOA community composition but less for AOB, whereas sediment depths might contribute to the AOB community shift. The diversity of AOA communities was higher than that of AOB across all four niches. Archaeal and bacterial amoA genes (encoding for the alpha-subunit of ammonia monooxygenases) were most diverse in the dry-land niche, indicating O2 availability might favor ammonia oxidation. The majority of AOA amoA sequences belonged to the Soil/sediment Cluster B in the freshwater wetland ecosystems, while the dominant AOB amoA sequences were affiliated with Nitrosospira-like cluster. In the Nitrosospira-like cluster, AOB amoA gene sequences affiliated with the uncultured ammonia-oxidizing beta-proteobacteria constituted the largest portion (99%). Moreover, independent methods for phylogenetic tree analysis supported high parsimony bootstrap values. As a consequence, it is proposed that Nitrosospira-like amoA gene sequences recovered in this study represent a potentially novel cluster, grouping with the sequences from Gulf of Mexico deposited in the public databases.

  6. Diversity Surveys and Evolutionary Relationships of aoxB Genes in Aerobic Arsenite-Oxidizing Bacteria▿ †

    PubMed Central

    Quéméneur, Marianne; Heinrich-Salmeron, Audrey; Muller, Daniel; Lièvremont, Didier; Jauzein, Michel; Bertin, Philippe N.; Garrido, Francis; Joulian, Catherine

    2008-01-01

    A new primer set was designed to specifically amplify ca. 1,100 bp of aoxB genes encoding the As(III) oxidase catalytic subunit from taxonomically diverse aerobic As(III)-oxidizing bacteria. Comparative analysis of AoxB protein sequences showed variable conservation levels and highlighted the conservation of essential amino acids and structural motifs. AoxB phylogeny of pure strains showed well-discriminated taxonomic groups and was similar to 16S rRNA phylogeny. Alphaproteobacteria-, Betaproteobacteria-, and Gammaproteobacteria-related sequences were retrieved from environmental surveys, demonstrating their prevalence in mesophilic As-contaminated soils. Our study underlines the usefulness of the aoxB gene as a functional marker of aerobic As(III) oxidizers. PMID:18502920

  7. Development of Ni-Ba(Zr,Y)O3 cermet anodes for direct ammonia-fueled solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Miyazaki, Kazunari; Okanishi, Takeou; Muroyama, Hiroki; Matsui, Toshiaki; Eguchi, Koichi

    2017-10-01

    In this study, the availability of Ni-Ba(Zr,Y)O3-δ (BZY) cermet for the anode of direct ammonia-fueled solid oxide fuel cells (SOFCs) is evaluated. In this device, the anodes need to be active for the catalytic ammonia decomposition as well as the electrochemical hydrogen oxidation. In the catalytic activity test, ammonia decomposes completely over Ni-BZY at ca. 600 °C, while higher temperature is required to accomplish the complete decomposition over the conventional SOFC anode of Ni-yttria-stabilized zirconia cermet. The high activity of Ni-BZY is attributed to the high basicity of BZY and the high resistance to hydrogen poisoning effect. The electrochemical property of Ni-BZY anode is also evaluated with the anode-supported cell of Ni-BZY|BZY|Pt at 600-700 °C with feeding ammonia or hydrogen as a fuel. Since the residence time of ammonia fuel in the thick Ni-BZY anode is long, the difference in the cell performance between two fuels is relatively small. Furthermore, it is proved that the steam concentration in the fuel strongly affects the cell performance. We find that this factor is important to satisfy the above mentioned requirements for the anode of direct ammonia-fueled SOFCs. Throughout this study, it is concluded that Ni-BZY cermet will be a promising anode.

  8. Ammonia exposure and subsequent recovery trigger oxidative stress responses in juveniles of Brazilian flounder Paralichthys orbignyanus.

    PubMed

    Maltez, Lucas Campos; Stringhetta, Giovanna Rodrigues; Enamorado, Alain Danilo; Okamoto, Marcelo Hideo; Romano, Luis Alberto; Monserrat, José María; Sampaio, Luís André; Garcia, Luciano

    2017-12-01

    The effects of ammonia exposure and recovery on oxidative stress parameters and histology of juvenile Brazilian flounder Paralichthys orbignyanus were evaluated. The fish were exposed to 0.12, 0.28 and 0.57 mg NH 3 -N L -1 , plus a control, for 10 days followed by the same recovery time in ammonia-free water. Gill, liver and muscle samples (n = 9) were collected after 1, 5 and 10 days of exposure and after recovery for oxidative stress analysis (antioxidant capacity against peroxyl radicals (ACAP); glutathione S-transferase (GST) activity; lipoperoxidation levels measured through thiobarbituric acid reactive substances (TBARS) content). For histological assessment, gill, liver and brain samples were collected. Exposure to all NH 3 -N concentrations induced different time- and dose-dependent changes in oxidative stress parameters. Reduced antioxidant capacity of the liver and muscle and enhanced TBARS levels in the gills and liver were demonstrated. Differently, a high ammonia concentration elicited lower hepatic TBARS levels. Enhanced GST activity in all organs and increased antioxidant capacity of the gills were also observed. No ammonia-induced histopathological effects were demonstrated. After recovery, most parameters (liver ACAP, GST activity in the muscle and liver and TBARS in the gills) returned to baseline levels. However, liver TBARS and gill GST activity remained altered 0.57 mg NH 3 -N L -1 treatment. The recovery period also led to a decrease in gill antioxidant capacity and an increase in muscle antioxidant capacity. In conclusion, a concentration of 0.12 mg NH 3 -N L -1 induces oxidative stress and antioxidant responses in juvenile Brazilian flounder. Moreover, a 10-day recovery period is not sufficient to restore fish homeostasis.

  9. The distribution and relative abundance of ammonia-oxidizing bacteria in lakes of the McMurdo Dry Valley, Antarctica

    USGS Publications Warehouse

    Voytek, M.A.; Priscu, J.C.; Ward, B.B.

    1999-01-01

    Marked differences in the concentrations of major ions and cations, macronutrient chemistry and general trophic status exist among the lakes of the McMurdo dry valleys in Antarctica. These differences have been attributed to both variations in stream inputs and in situ lake processes (Priscu, 1995; Lizotte et al., 1996, Spigel and Priscu, 1996). This study examines the role of nitrifying bacteria in nitrogen transformations in these lakes. Applying two polymerase chain reaction (PCR) assays targeting the 16S rRNA genes of ammonia-oxidizing bacteria and the active site of the ammonia monooxygenase gene (amoA), the distribution of ammonia-oxidizers was examined in six Antarctic lakes: Lake Bonney, Lake Hoare, Lake Fryxell and Lake Joyce in the Taylor Valley, Lake Miers in the the Miers Valley and Lake Vanda in the Wright Valley. Using a two stage amplification procedure, ammonia-oxidizers from both the beta and gamma- subclasses of the Proteobacteria were detected and their relative abundances were determined in samples collected from all sites. Ammonia-oxidizers were detected in all lakes sampled. Members of the gamma subclass were only present in the saline lakes. In general, nitrifiers were most abundant at depths above the pycnocline and were usually associated with lower concentrations of NH4 and elevated concentrations of NO3 or NO2. The distribution of nitrifiers suggests that the primary N2O peak observed in most of the lakes was produced via nitrification. Preliminary data on the rate of nitrification (Priscu et al., 1996) support the occurrence of nitrification and the presence of nitrifiers at the depth intervals where nitrifiers were detected. In all lakes, except Lake Miers, the data indicate that nitrifying bacteria have an important role in the vertical distribution of nitrogen compounds in these systems.

  10. Aerobic granulation in a modified oxidation ditch with an adjustable volume intraclarifier.

    PubMed

    Li, Jun; Cai, Ang; Wang, Miao; Ding, Libin; Ni, Yongjiong

    2014-04-01

    A modified oxidation ditch (MOD) with an adjustable volume intraclarifier was proposed and used to achieve aerobic sludge granulation in continuous flow process. This MOD with working volume of 60L treated onsite wastewater from a town. Excellent aerobic granules with mean diameter of 600μm and sludge volume index (SVI) of 44mL/g were obtained in 120day. Bacterial community analysis revealed that most species from seed sludge were preserved in both MOD and granule SBR (G-SBR) except bacteria (Bacteroidetes) might be easily washed out during granulation. Some different bacterial communities were found in sludges from sequencing batch and continuous flow reactors. Presence of metal ions and inorganics in raw wastewater had positive effect on granule formation, but an adjustable volume intraclarifier for controlling selection pressure and deleting return sludge pump played a key role in aerobic sludge granulation. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Removal of Pesticides and Inorganic Contaminants in Anaerobic and Aerobic Biological Contactors

    EPA Science Inventory

    This presentation contains data on the removal of pesticides (acetochlor, clethodim, dicrotophos), ammonia, nitrate, bromate and perchlorate through aerobic and anaerobic biological treatment processes.

  12. Biochar type and factors affecting N transformation, ammonia volatilization, and nitrous oxide emissions

    USDA-ARS?s Scientific Manuscript database

    Soil amendment with biochar has shown the potential to improve nitrogen (N) availability for plant uptake and reduce environmental losses via ammonia (NH3) and nitrous oxide (N2O) emissions. There are still many unknowns on how biochar type and soil conditions affect N dynamics and processes associa...

  13. Treatment of Ammonia Nitrogen Wastewater in Low Concentration by Two-Stage Ozonization.

    PubMed

    Luo, Xianping; Yan, Qun; Wang, Chunying; Luo, Caigui; Zhou, Nana; Jian, Chensheng

    2015-09-23

    Ammonia nitrogen wastewater (about 100 mg/L) was treated by two-stage ozone oxidation method. The effects of ozone flow rate and initial pH on ammonia removal were studied, and the mechanism of ammonia nitrogen removal by ozone oxidation was discussed. After the primary stage of ozone oxidation, the ammonia removal efficiency reached 59.32% and pH decreased to 6.63 under conditions of 1 L/min ozone flow rate and initial pH 11. Then, the removal efficiency could be over 85% (the left ammonia concentration was lower than 15 mg/L) after the second stage, which means the wastewater could have met the national discharge standards of China. Besides, the mechanism of ammonia removal by ozone oxidation was proposed by detecting the products of the oxidation: ozone oxidation directly and ·OH oxidation; ammonia was mainly transformed into NO₃(-)-N, less into NO₂(-)-N, not into N₂.

  14. Supplementation with vitamin A enhances oxidative stress in the lungs of rats submitted to aerobic exercise.

    PubMed

    Gasparotto, Juciano; Petiz, Lyvia Lintzmaier; Girardi, Carolina Saibro; Bortolin, Rafael Calixto; de Vargas, Amanda Rodrigues; Henkin, Bernardo Saldanha; Chaves, Paloma Rodrigues; Roncato, Sabrina; Matté, Cristiane; Zanotto-Filho, Alfeu; Moreira, José Cláudio Fonseca; Gelain, Daniel Pens

    2015-12-01

    Exercise training induces reactive oxygen species production and low levels of oxidative damage, which are required for induction of antioxidant defenses and tissue adaptation. This process is physiological and essential to improve physical conditioning and performance. During exercise, endogenous antioxidants are recruited to prevent excessive oxidative stress, demanding appropriate intake of antioxidants from diet or supplements; in this context, the search for vitamin supplements that enhance the antioxidant defenses and improve exercise performance has been continuously increasing. On the other hand, excess of antioxidants may hinder the pro-oxidant signals necessary for this process of adaptation. The aim of this study was to investigate the effects of vitamin A supplementation (2000 IU/kg, oral) upon oxidative stress and parameters of pro-inflammatory signaling in lungs of rats submitted to aerobic exercise (swimming protocol). When combined with exercise, vitamin A inhibited biochemical parameters of adaptation/conditioning by attenuating exercise-induced antioxidant enzymes (superoxide dismutase and glutathione peroxidase) and decreasing the content of the receptor for advanced glycation end-products. Increased oxidative damage to proteins (carbonylation) and lipids (lipoperoxidation) was also observed in these animals. In sedentary animals, vitamin A decreased superoxide dismutase and increased lipoperoxidation. Vitamin A also enhanced the levels of tumor necrosis factor alpha and decreased interleukin-10, effects partially reversed by aerobic training. Taken together, the results presented herein point to negative effects associated with vitamin A supplementation at the specific dose here used upon oxidative stress and pro-inflammatory cytokines in lung tissues of rats submitted to aerobic exercise.

  15. Selective C(sp3 )-H Aerobic Oxidation Enabled by Decatungstate Photocatalysis in Flow.

    PubMed

    Laudadio, Gabriele; Govaerts, Sebastian; Wang, Ying; Ravelli, Davide; Koolman, Hannes F; Fagnoni, Maurizio; Djuric, Stevan W; Noël, Timothy

    2018-04-03

    A mild and selective C(sp 3 )-H aerobic oxidation enabled by decatungstate photocatalysis has been developed. The reaction can be significantly improved in a microflow reactor enabling the safe use of oxygen and enhanced irradiation of the reaction mixture. Our method allows for the oxidation of both activated and unactivated C-H bonds (30 examples). The ability to selectively oxidize natural scaffolds, such as (-)-ambroxide, pregnenolone acetate, (+)-sclareolide, and artemisinin, exemplifies the utility of this new method. © 2018 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  16. Evaluation of oxidative stress in mice subjected to aerobic exercise.

    PubMed

    Lima, Mônica Cruvinel de; Marks, Guido; Silva, Iandara Schettert; Silva, Baldomero Antonio Kato da; Cônsolo, Lourdes Zélia Zanoni; Nogueira, Gabriel Bogalho

    2012-08-01

    To evaluate the influence of aerobic exercise on oxidative stress in mice. The study included twenty female mice Mus musculus-Swiss divided into two groups: sedentary control (GA) and exercise (GB), each containing ten animals. All animals underwent an adaptation period of seven days isolated in individual boxes. After this period, the animals in the exercise group (GB) were trained in angled running wheel with circumference of 25 cm assembled on an articulated axle during five minutes for three consecutive days. On the fourth day, they underwent an exercise program of one session lasting 45 minutes. The evaluation of oxidative stress was performed by determining the levels of malondialhyde derived of lipid peroxidation by the TBA method. The samples were read in a spectrophotometer at 535 nm. No significant difference was observed in the intergroup comparison of MDA levels in the tissues evaluated. A significant difference was observed in the intragroup comparison of MDA levels in the control group (p = 0.0201).The Tukeys' post hoc test indicated significantly lower values of MDA in the smooth muscle in relation to plasma. In the analysis of variance in the exercise group, a significant difference between tissues (p = 0.0009), with significantly lower values in the smooth muscle in relation to plasma (p<0.001) and higher in striated muscle in relation to smooth muscle (p<0.05) was observed. There was no change in the analysis of oxidative stress in mice which were undergone a single session of aerobic exercise.

  17. Long-term aerobic exercise increases redox-active iron through nitric oxide in rat hippocampus.

    PubMed

    Chen, Qian; Xiao, De-Sheng

    2014-01-30

    Adult hippocampus is highly vulnerable to iron-induced oxidative stress. Aerobic exercise has been proposed to reduce oxidative stress but the findings in the hippocampus are conflicting. This study aimed to observe the changes of redox-active iron and concomitant regulation of cellular iron homeostasis in the hippocampus by aerobic exercise, and possible regulatory effect of nitric oxide (NO). A randomized controlled study was designed in the rats with swimming exercise treatment (for 3 months) and/or an unselective inhibitor of NO synthase (NOS) (L-NAME) treatment. The results from the bleomycin-detectable iron assay showed additional redox-active iron in the hippocampus by exercise treatment. The results from nonheme iron content assay, combined with the redox-active iron content, showed increased storage iron content by exercise treatment. NOx (nitrate plus nitrite) assay showed increased NOx content by exercise treatment. The results from the Western blot assay showed decreased ferroportin expression, no changes of TfR1 and DMT1 expressions, increased IRP1 and IRP2 expression, increased expressions of eNOS and nNOS rather than iNOS. In these effects of exercise treatment, the increased redox-active iron content, storage iron content, IRP1 and IRP2 expressions were completely reversed by L-NAME treatment, and decreased ferroportin expression was in part reversed by L-NAME. L-NAME treatment completely inhibited increased NOx and both eNOS and nNOS expression in the hippocampus. Our findings suggest that aerobic exercise could increase the redox-active iron in the hippocampus, indicating an increase in the capacity to generate hydroxyl radicals through the Fenton reactions, and aerobic exercise-induced iron accumulation in the hippocampus might mainly result from the role of the endogenous NO. Copyright © 2013 Elsevier Inc. All rights reserved.

  18. Patterns of Community Change among Ammonia Oxidizers in Meadow Soils upon Long-Term Incubation at Different Temperatures

    PubMed Central

    Avrahami, Sharon; Conrad, Ralf

    2003-01-01

    The effect of temperature on the community structure of ammonia-oxidizing bacteria was investigated in three different meadow soils. Two of the soils (OMS and GMS) were acidic (pH 5.0 to 5.8) and from sites in Germany with low annual mean temperature (about 10°C), while KMS soil was slightly alkaline (pH 7.9) and from a site in Israel with a high annual mean temperature (about 22°C). The soils were fertilized and incubated for up to 20 weeks in a moist state and as a buffered (pH 7) slurry amended with urea at different incubation temperatures (4 to 37°C). OMS soil was also incubated with less fertilizer than the other soils. The community structure of ammonia oxidizers was analyzed before and after incubation by denaturing gradient gel electrophoresis (DGGE) of the amoA gene, which codes for the α subunit of ammonia monooxygenase. All amoA gene sequences found belonged to the genus Nitrosospira. The analysis showed community change due to temperature both in moist soil and in the soil slurry. Two patterns of community change were observed. One pattern was a change between the different Nitrosospira clusters, which was observed in moist soil and slurry incubations of GMS and OMS. Nitrosospira AmoA cluster 1 was mainly detected below 30°C, while Nitrosospira cluster 4 was predominant at 25°C. Nitrosospira clusters 3a, 3b, and 9 dominated at 30°C. The second pattern, observed in KMS, showed a community shift predominantly within a single Nitrosospira cluster. The sequences of the individual DGGE bands that exhibited different trends with temperature belonged almost exclusively to Nitrosospira cluster 3a. We conclude that ammonia oxidizer populations are influenced by temperature. In addition, we confirmed previous observations that N fertilizer also influences the community structure of ammonia oxidizers. Thus, Nitrosospira cluster 1 was absent in OMS soil treated with less fertilizer, while Nitrosospira cluster 9 was only found in the sample given less

  19. Decentralised black water treatment by combined auto-thermal aerobic digestion and ammonia - A pilot study optimising treatment capacity.

    PubMed

    Nordin, A; Göttert, D; Vinnerås, B

    2018-02-01

    Partial heating of black water by auto-thermal aerobic digestion was combined with the addition of 1% w/w urea and monitoring of pathogens and indicator organisms over a 21-day period. After initial mixing, the 160 m 3 black water (60 m 3 heated and 100 m 3 non-heated) was left undisturbed. The urea was confirmed to be fully degraded into ammonia (5.1 g N L -1 ) first after 14 days, while the pH stabilised at around 9.2 after one week. The initial temperature of 17 °C fell by 6 °C during the study. E. coli and Salmonella spp., which are sensitive to ammonia, were inactivated during the first few days of the study, despite the urea only being partly hydrolysed. At day 14, f-RNA bacteriophages could also no longer be detected. The more persistent somatic coliphages, Enterococcus spp. and Ascaris eggs, showed significant but slow inactivation. The treatment proved to be efficient with regards to salmonella, which is a target pathogen in the Swedish context, but for parasite egg inactivation a higher temperature was required. The treatment would benefit from more frequent stirring to speed up the hydrolysis of urea and thus improve treatment efficiency. The alternative treatment scheme could increase capacity by 2.4 times, albeit with a 40% higher cost per volume due to the increased use of urea. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Resistance and aerobic exercise have similar effects on 24-h nutrient oxidation.

    PubMed

    Melanson, Edward L; Sharp, Teresa A; Seagle, Helen M; Donahoo, William T; Grunwald, Gary K; Peters, John C; Hamilton, Jere T; Hill, James O

    2002-11-01

    Whether resistance exercise is as effective as aerobic exercise for body-weight management is debated. To compare 24-h energy expenditure (EE) and macronutrient oxidation elicited by comparable bouts of stationary cycling (BK) and weightlifting (WTS). 24-h EE and macronutrient oxidation were measured in 10 nonobese male subjects on three occasions using whole-room indirect calorimetry. BK and WTS days were compared with a nonexercise control day (Con). During BK, subjects exercised for 49 +/- 7 min (mean +/- SEM) at 70% of OV(2max) and expended 546 +/- 16 kcal. During WTS, subjects performed a 70-min circuit consisting of four sets of 10 different exercises at 70% of exercise-specific 1-repetition maximum and expended 448 +/- 21 kcal (P < 0.001 vs BK). 24-h EE on BK and WTS days (2,787 +/- 76 kcal x d(-1), 2,730 +/- 106 kcal x d(-1), respectively, P > 0.05) was elevated compared with Con (2,260 +/- 96 kcal x d(-1), P < 0.001), but 24-h respiratory exchange ratio (RER) was not different. 24-h carbohydrate oxidation was significantly elevated on the exercise days (BK = 370 +/- 18 g x d(-1), WTS = 349 +/- 23 g x d(-1), P > 0.05) compared with Con (249 +/- 29 g x d(-1), P = 0.04). 24-h fat and protein oxidation were the same on BK, WTS, and Con days. EE and macronutrient oxidation in the periods after exercise also did not differ across conditions. In men, resistance exercise has a similar effect on 24-h EE and macronutrient oxidation as a comparable bout of aerobic exercise. Neither exercise produced an increase in 24-h fat oxidation above that observed on a nonexercise control day.

  1. Second-Order Biomimicry: In Situ Oxidative Self-Processing Converts Copper(I)/Diamine Precursor into a Highly Active Aerobic Oxidation Catalyst.

    PubMed

    McCann, Scott D; Lumb, Jean-Philip; Arndtsen, Bruce A; Stahl, Shannon S

    2017-04-26

    A homogeneous Cu-based catalyst system consisting of [Cu(MeCN) 4 ]PF 6 , N , N '-di- tert -butylethylenediamine (DBED), and p -( N , N -dimethylamino)pyridine (DMAP) mediates efficient aerobic oxidation of alcohols. Mechanistic study of this reaction shows that the catalyst undergoes an in situ oxidative self-processing step, resulting in conversion of DBED into a nitroxyl that serves as an efficient cocatalyst for aerobic alcohol oxidation. Insights into this behavior are gained from kinetic studies, which reveal an induction period at the beginning of the reaction that correlates with the oxidative self-processing step, EPR spectroscopic analysis of the catalytic reaction mixture, which shows the buildup of the organic nitroxyl species during steady state turnover, and independent synthesis of oxygenated DBED derivatives, which are shown to serve as effective cocatalysts and eliminate the induction period in the reaction. The overall mechanism bears considerable resemblance to enzymatic reactivity. Most notable is the "oxygenase"-type self-processing step that mirrors generation of catalytic cofactors in enzymes via post-translational modification of amino acid side chains. This higher-order function within a synthetic catalyst system presents new opportunities for the discovery and development of biomimetic catalysts.

  2. Second-Order Biomimicry: In Situ Oxidative Self-Processing Converts Copper(I)/Diamine Precursor into a Highly Active Aerobic Oxidation Catalyst

    PubMed Central

    2017-01-01

    A homogeneous Cu-based catalyst system consisting of [Cu(MeCN)4]PF6, N,N′-di-tert-butylethylenediamine (DBED), and p-(N,N-dimethylamino)pyridine (DMAP) mediates efficient aerobic oxidation of alcohols. Mechanistic study of this reaction shows that the catalyst undergoes an in situ oxidative self-processing step, resulting in conversion of DBED into a nitroxyl that serves as an efficient cocatalyst for aerobic alcohol oxidation. Insights into this behavior are gained from kinetic studies, which reveal an induction period at the beginning of the reaction that correlates with the oxidative self-processing step, EPR spectroscopic analysis of the catalytic reaction mixture, which shows the buildup of the organic nitroxyl species during steady state turnover, and independent synthesis of oxygenated DBED derivatives, which are shown to serve as effective cocatalysts and eliminate the induction period in the reaction. The overall mechanism bears considerable resemblance to enzymatic reactivity. Most notable is the “oxygenase”-type self-processing step that mirrors generation of catalytic cofactors in enzymes via post-translational modification of amino acid side chains. This higher-order function within a synthetic catalyst system presents new opportunities for the discovery and development of biomimetic catalysts. PMID:28470049

  3. Treatment of Ammonia Nitrogen Wastewater in Low Concentration by Two-Stage Ozonization

    PubMed Central

    Luo, Xianping; Yan, Qun; Wang, Chunying; Luo, Caigui; Zhou, Nana; Jian, Chensheng

    2015-01-01

    Ammonia nitrogen wastewater (about 100 mg/L) was treated by two-stage ozone oxidation method. The effects of ozone flow rate and initial pH on ammonia removal were studied, and the mechanism of ammonia nitrogen removal by ozone oxidation was discussed. After the primary stage of ozone oxidation, the ammonia removal efficiency reached 59.32% and pH decreased to 6.63 under conditions of 1 L/min ozone flow rate and initial pH 11. Then, the removal efficiency could be over 85% (the left ammonia concentration was lower than 15 mg/L) after the second stage, which means the wastewater could have met the national discharge standards of China. Besides, the mechanism of ammonia removal by ozone oxidation was proposed by detecting the products of the oxidation: ozone oxidation directly and ·OH oxidation; ammonia was mainly transformed into NO3−-N, less into NO2−-N, not into N2. PMID:26404353

  4. Cu-catalyzed aerobic oxidative esterification of acetophenones with alcohols to α-ketoesters.

    PubMed

    Xu, Xuezhao; Ding, Wen; Lin, Yuanguang; Song, Qiuling

    2015-02-06

    Copper-catalyzed aerobic oxidative esterification of acetophenones with alcohols using molecular oxygen has been developed to form a broad range of α-ketoesters in good yields. In addition to reporting scope and limitations of our new method, mechanism studies are reported that reveal that the carbonyl oxygen in the ester mainly originated from dioxygen.

  5. Enhanced and selective ammonia sensing of reduced graphene oxide based chemo resistive sensor at room temperature

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kumar, Ramesh, E-mail: rameshphysicsdu@gmail.com; Kaur, Amarjeet, E-mail: amarkaur@physics.du.ac.in

    The reduced graphene oxide thin films were fabricated by using the spin coating method. The reduced graphene oxide samples were characterised by Raman studies to obtain corresponding D and G bands at 1360 and 1590 cm{sup −1} respectively. Fourier transform infra-red (FTIR) spectra consists of peak corresponds to sp{sup 2} hybridisation of carbon atoms at 1560 cm{sup −1}. The reduced graphene oxide based chemoresistive sensor exhibited a p-type semiconductor behaviour in ambient conditions and showed good sensitivity to different concentration of ammonia from 25 ppm to 500 ppm and excellent selectivity at room temperature. The sensor displays selectivity to several hazardous vapours such asmore » methanol, ethanol, acetone and hydrazine hydrate. The sensor demonstrated a sensitivity of 9.8 at 25 ppm concentration of ammonia with response time of 163 seconds.« less

  6. Development and Comparison of the Substrate Scope of Pd-Catalysts for the Aerobic Oxidation of Alcohols

    PubMed Central

    Schultz, Mitchell J.; Hamilton, Steven S.; Jensen, David R.; Sigman, Matthew S.

    2009-01-01

    Three catalysts for aerobic oxidation of alcohols are discussed and the effectiveness of each is evaluated for allylic, benzylic, aliphatic, and functionalized alcohols. Additionally, chiral nonracemic substrates as well as chemoselective and diastereoselective oxidations are investigated. In this study, the most convenient system for the Pd-catalyzed aerobic oxidation of alcohols is Pd(OAc)2 in combination with triethylamine. This system functions effectively for the majority of alcohols tested and uses mild conditions (3 to 5 mol % of catalyst, room temperature). Pd(IiPr)(OAc)2(H2O) (1) also successfully oxidizes the majority of alcohols evaluated. This system has the advantage of significantly lowering catalyst loadings but requires higher temperatures (0.1 to 1 mol % of catalyst, 60 °C). A new catalyst is also disclosed, Pd(IiPr)(OPiv)2 (2). This catalyst operates under very mild conditions (1 mol %, room temperature, and air as the O2 source) but with a more limited substrate scope. PMID:15844968

  7. Detection by denaturing gradient gel electrophoresis of ammonia-oxidizing bacteria in microcosms of crude oil-contaminated mangrove sediments.

    PubMed

    dos Santos, A C F; Marques, E L S; Gross, E; Souza, S S; Dias, J C T; Brendel, M; Rezende, R P

    2012-01-27

    Currently, the effect of crude oil on ammonia-oxidizing bacterium communities from mangrove sediments is little understood. We studied the diversity of ammonia-oxidizing bacteria in mangrove microcosm experiments using mangrove sediments contaminated with 0.1, 0.5, 1, 2, and 5% crude oil as well as non-contaminated control and landfarm soil from near an oil refinery in Camamu Bay in Bahia, Brazil. The evolution of CO(2) production in all crude oil-contaminated microcosms showed potential for mineralization. Cluster analysis of denaturing gradient gel electrophoresis-derived samples generated with primers for gene amoA, which encodes the functional enzyme ammonia monooxygenase, showed differences in the sample contaminated with 5% compared to the other samples. Principal component analysis showed divergence of the non-contaminated samples from the 5% crude oil-contaminated sediment. A Venn diagram generated from the banding pattern of PCR-denaturing gradient gel electrophoresis was used to look for operational taxonomic units (OTUs) in common. Eight OTUs were found in non-contaminated sediments and in samples contaminated with 0.5, 1, or 2% crude oil. A Jaccard similarity index of 50% was found for samples contaminated with 0.1, 0.5, 1, and 2% crude oil. This is the first study that focuses on the impact of crude oil on the ammonia-oxidizing bacterium community in mangrove sediments from Camamu Bay.

  8. Active ammonia oxidizers in an acidic soil are phylogenetically closely related to neutrophilic archaeon.

    PubMed

    Wang, Baozhan; Zheng, Yan; Huang, Rong; Zhou, Xue; Wang, Dongmei; He, Yuanqiu; Jia, Zhongjun

    2014-03-01

    All cultivated ammonia-oxidizing archaea (AOA) within the Nitrososphaera cluster (former soil group 1.1b) are neutrophilic. Molecular surveys also indicate the existence of Nitrososphaera-like phylotypes in acidic soil, but their ecological roles are poorly understood. In this study, we present molecular evidence for the chemolithoautotrophic growth of Nitrososphaera-like AOA in an acidic soil with pH 4.92 using DNA-based stable isotope probing (SIP). Soil microcosm incubations demonstrated that nitrification was stimulated by urea fertilization and accompanied by a significant increase in the abundance of AOA rather than ammonia-oxidizing bacteria (AOB). Real-time PCR analysis of amoA genes as a function of the buoyant density of the DNA gradient following the ultracentrifugation of the total DNA extracted from SIP microcosms indicated a substantial growth of soil AOA during nitrification. Pyrosequencing of the total 16S rRNA genes in the "heavy" DNA fractions suggested that archaeal communities were labeled to a much greater extent than soil AOB. Acetylene inhibition further showed that (13)CO2 assimilation by nitrifying communities depended solely on ammonia oxidation activity, suggesting a chemolithoautotrophic lifestyle. Phylogenetic analysis of both (13)C-labeled amoA and 16S rRNA genes revealed that most of the active AOA were phylogenetically closely related to the neutrophilic strains Nitrososphaera viennensis EN76 and JG1 within the Nitrososphaera cluster. Our results provide strong evidence for the adaptive growth of Nitrososphaera-like AOA in acidic soil, suggesting a greater metabolic versatility of soil AOA than previously appreciated.

  9. Active Ammonia Oxidizers in an Acidic Soil Are Phylogenetically Closely Related to Neutrophilic Archaeon

    PubMed Central

    Wang, Baozhan; Zheng, Yan; Huang, Rong; Zhou, Xue; Wang, Dongmei; He, Yuanqiu

    2014-01-01

    All cultivated ammonia-oxidizing archaea (AOA) within the Nitrososphaera cluster (former soil group 1.1b) are neutrophilic. Molecular surveys also indicate the existence of Nitrososphaera-like phylotypes in acidic soil, but their ecological roles are poorly understood. In this study, we present molecular evidence for the chemolithoautotrophic growth of Nitrososphaera-like AOA in an acidic soil with pH 4.92 using DNA-based stable isotope probing (SIP). Soil microcosm incubations demonstrated that nitrification was stimulated by urea fertilization and accompanied by a significant increase in the abundance of AOA rather than ammonia-oxidizing bacteria (AOB). Real-time PCR analysis of amoA genes as a function of the buoyant density of the DNA gradient following the ultracentrifugation of the total DNA extracted from SIP microcosms indicated a substantial growth of soil AOA during nitrification. Pyrosequencing of the total 16S rRNA genes in the “heavy” DNA fractions suggested that archaeal communities were labeled to a much greater extent than soil AOB. Acetylene inhibition further showed that 13CO2 assimilation by nitrifying communities depended solely on ammonia oxidation activity, suggesting a chemolithoautotrophic lifestyle. Phylogenetic analysis of both 13C-labeled amoA and 16S rRNA genes revealed that most of the active AOA were phylogenetically closely related to the neutrophilic strains Nitrososphaera viennensis EN76 and JG1 within the Nitrososphaera cluster. Our results provide strong evidence for the adaptive growth of Nitrososphaera-like AOA in acidic soil, suggesting a greater metabolic versatility of soil AOA than previously appreciated. PMID:24375137

  10. Combined Flux Chamber and Genomics Approach Links Nitrous Acid Emissions to Ammonia Oxidizing Bacteria and Archaea in Urban and Agricultural Soil.

    PubMed

    Scharko, Nicole K; Schütte, Ursel M E; Berke, Andrew E; Banina, Lauren; Peel, Hannah R; Donaldson, Melissa A; Hemmerich, Chris; White, Jeffrey R; Raff, Jonathan D

    2015-12-01

    Nitrous acid (HONO) is a photochemical source of hydroxyl radical and nitric oxide in the atmosphere that stems from abiotic and biogenic processes, including the activity of ammonia-oxidizing soil microbes. HONO fluxes were measured from agricultural and urban soil in mesocosm studies aimed at characterizing biogenic sources and linking them to indigenous microbial consortia. Fluxes of HONO from agricultural and urban soil were suppressed by addition of a nitrification inhibitor and enhanced by amendment with ammonium (NH4(+)), with peaks at 19 and 8 ng m(-2) s(-1), respectively. In addition, both agricultural and urban soils were observed to convert (15)NH4(+) to HO(15)NO. Genomic surveys of soil samples revealed that 1.5-6% of total expressed 16S rRNA sequences detected belonged to known ammonia oxidizing bacteria and archaea. Peak fluxes of HONO were directly related to the abundance of ammonia-oxidizer sequences, which in turn depended on soil pH. Peak HONO fluxes under fertilized conditions are comparable in magnitude to fluxes reported during field campaigns. The results suggest that biogenic HONO emissions will be important in soil environments that exhibit high nitrification rates (e.g., agricultural soil) although the widespread occurrence of ammonia oxidizers implies that biogenic HONO emissions are also possible in the urban and remote environment.

  11. Partial nitrification using aerobic granules in continuous-flow reactor: rapid startup.

    PubMed

    Wan, Chunli; Sun, Supu; Lee, Duu-Jong; Liu, Xiang; Wang, Li; Yang, Xue; Pan, Xiangliang

    2013-08-01

    This study applied a novel strategy to rapid startup of partial nitrification in continuous-flow reactor using aerobic granules. Mature aerobic granules were first cultivated in a sequencing batch reactor at high chemical oxygen demand in 16 days. The strains including the Pseudoxanthomonas mexicana strain were enriched in cultivated granules to enhance their structural stability. Then the cultivated granules were incubated in a continuous-flow reactor with influent chemical oxygen deamnad being stepped decreased from 1,500 ± 100 (0-19 days) to 750 ± 50 (20-30 days), and then to 350 ± 50 mg l(-1) (31-50 days); while in the final stage 350 mg l(-1) bicarbonate was also supplied. Using this strategy the ammonia-oxidizing bacterium, Nitrosomonas europaea, was enriched in the incubated granules to achieve partial nitrification efficiency of 85-90% since 36 days and onwards. The partial nitrification granules were successfully harvested after 52 days, a period much shorter than those reported in literature. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. Aerobic and Electrochemical Oxidations with N-Oxyl Reagents

    NASA Astrophysics Data System (ADS)

    Miles, Kelsey C.

    Selective oxidation of organic compounds represents a significant challenge for chemical transformations. Oxidation methods that utilize nitroxyl catalysts have become increasingly attractive and include Cu/nitroxyl and nitroxyl/NO x co-catalyst systems. Electrochemical activation of nitroxyls is also well known and offers an appealing alternative to the use of chemical co-oxidants. However, academic and industrial organic synthetic communities have not widely adopted electrochemical methods. Nitroxyl catalysts facilitate effective and selective oxidation of alcohols and aldehydes to ketones and carboxylic acids. Selective benzylic, allylic, and alpha-heteroatom C-H abstraction can also be achieved with nitroxyls and provides access to oxygenated products when used in combination with molecular oxygen as a radical trap. This thesis reports various chemical and electrochemical oxidation methods that were developed using nitroxyl mediators. Chapter 1 provides a short review on practical aerobic alcohol oxidation with Cu/nitroxyl and nitroxyl/NO x systems and emphasizes the utility of bicyclic nitroxyls as co-catalysts. In Chapter 2, the combination of these bicyclic nitroxyls with NOx is explored for development of a mild oxidation of alpha-chiral aryl aldehydes and showcases a sequential asymmetric hydroformylation/oxidation method. Chapter 3 reports the synthesis and characterization of two novel Cu/bicyclic nitroxyl complexes and the electronic structure analysis of these complexes. Chapter 4 highlights the electrochemical activation of various nitroxyls and reports an in-depth study on electrochemical alcohol oxidation and compares the reactivity of nitroxyls under electrochemical or chemical activation. N-oxyls can also participate in selective C-H abstraction, and Chapter 5 reports the chemical and electrochemical activation of N-oxyls for radical-mediated C-H oxygenation of (hetero)arylmethanes. For these electrochemical transformations, the development of

  13. Ammonia-limited conditions cause of Thaumarchaeal dominance in volcanic grassland soil.

    PubMed

    Daebeler, Anne; Bodelier, Paul L E; Hefting, Mariet M; Laanbroek, Hendrikus J

    2015-03-01

    The first step of nitrification is carried out by ammonia-oxidizing bacteria (AOB) and archaea (AOA). It is largely unknown, by which mechanisms these microbes are capable of coexistence and how their respective contribution to ammonia oxidation may differ with varying soil characteristics. To determine how different levels of ammonium availability influence the extent of archaeal and bacterial contributions to ammonia oxidation, microcosm incubations with controlled ammonium levels were conducted. Net nitrification was monitored and ammonia-oxidizer communities were quantified. Additionally, the nitrification inhibitor allylthiourea (ATU) was applied to discriminate between archaeal and bacterial contributions to soil ammonia oxidation. Thaumarchaeota, which were the only ammonia oxidizers detectable at the start of the incubation, grew in all microcosms, but AOB later became detectable in ammonium amended microcosms. Low and high additions of ammonium increasingly stimulated AOB growth, while AOA were only stimulated by the low addition. Treatment with ATU had no effect on net nitrification and sizes of ammonia-oxidizing communities suggesting that the effective concentration of ATU to discriminate between archaeal and bacterial ammonia oxidation is not the same in different soils. Our results support the niche-differentiating potential of ammonium concentration for AOA and AOB, and we conclude that ammonium limitation can be a major reason for absence of detectable AOB in soil. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  14. Oxidase catalysis via aerobically generated hypervalent iodine intermediates

    NASA Astrophysics Data System (ADS)

    Maity, Asim; Hyun, Sung-Min; Powers, David C.

    2018-02-01

    The development of sustainable oxidation chemistry demands strategies to harness O2 as a terminal oxidant. Oxidase catalysis, in which O2 serves as a chemical oxidant without necessitating incorporation of oxygen into reaction products, would allow diverse substrate functionalization chemistry to be coupled to O2 reduction. Direct O2 utilization suffers from intrinsic challenges imposed by the triplet ground state of O2 and the disparate electron inventories of four-electron O2 reduction and two-electron substrate oxidation. Here, we generate hypervalent iodine reagents—a broadly useful class of selective two-electron oxidants—from O2. This is achieved by intercepting reactive intermediates of aldehyde autoxidation to aerobically generate hypervalent iodine reagents for a broad array of substrate oxidation reactions. The use of aryl iodides as mediators of aerobic oxidation underpins an oxidase catalysis platform that couples substrate oxidation directly to O2 reduction. We anticipate that aerobically generated hypervalent iodine reagents will expand the scope of aerobic oxidation chemistry in chemical synthesis.

  15. Temporal variation of aerobic methane oxidation over a tidal cycle in a wetland of northern Taiwan.

    NASA Astrophysics Data System (ADS)

    Lee, T. Y.; Wang, P. L.; Lin, L. H.

    2017-12-01

    Aerobic methanotrophy plays an important role in controlling methane emitted from wetlands. However, the activity of aerobic methanotrophy regulated by temporal fluctuation of oxygen and methane supply in tidal wetlands is not well known. This study aims to examine the dynamics of methane fluxes and potential aerobic methane consumption rates in a tidal wetland of northern Taiwan, where the variation of environmental characteristics, such as sulfate and methane concentration in pore water has been demonstrated during a tidal cycle. Two field campaigns were carried out in December of 2016 and March of 2017. Fluxes of methane emission, methane concentrations in surface sediments and oxygen profiles were measured at different tidal phases. Besides, batch incubations were conducted on surface sediments in order to quantify potential microbial methane consumption rates and to derive the kinetic parameters for aerobic methanotrophy. Our results demonstrated temporal changes of the surface methane concentration and the methane emission flux during a tidal cycle, while the oxygen flux into the sediment was kept at a similar magnitude. The methane flux was low when the surface was exposed for both shortest and longest periods of time. The potential aerobic methane oxidation rate was high for sample collected from the surface sediments exposed the longest. No correlation could be found between the potential aerobic methane oxidation rate and either the oxygen downward flux or methane emission flux. The decoupled relationships between these observed rates and fluxes suggest that, rather than aerobic methanotrophy, heterotrophic respirations exert a profound control on oxygen flux, and the methane emission is not only been affected by methane consumption but also methane production at depths. The maximum potential rate and the half saturation concentration determined from the batch incubations were high for the surface sediments collected in low tide, suggesting that aerobic

  16. Tuning graphitic oxide for initiator- and metal-free aerobic epoxidation of linear alkenes

    NASA Astrophysics Data System (ADS)

    Pattisson, Samuel; Nowicka, Ewa; Gupta, Upendra N.; Shaw, Greg; Jenkins, Robert L.; Morgan, David J.; Knight, David W.; Hutchings, Graham J.

    2016-09-01

    Graphitic oxide has potential as a carbocatalyst for a wide range of reactions. Interest in this material has risen enormously due to it being a precursor to graphene via the chemical oxidation of graphite. Despite some studies suggesting that the chosen method of graphite oxidation can influence the physical properties of the graphitic oxide, the preparation method and extent of oxidation remain unresolved for catalytic applications. Here we show that tuning the graphitic oxide surface can be achieved by varying the amount and type of oxidant. The resulting materials differ in level of oxidation, surface oxygen content and functionality. Most importantly, we show that these graphitic oxide materials are active as unique carbocatalysts for low-temperature aerobic epoxidation of linear alkenes in the absence of initiator or metal. An optimum level of oxidation is necessary and materials produced via conventional permanganate-based methods are far from optimal.

  17. Selective C(sp3)−H Aerobic Oxidation Enabled by Decatungstate Photocatalysis in Flow

    PubMed Central

    Laudadio, Gabriele; Govaerts, Sebastian; Wang, Ying; Ravelli, Davide; Koolman, Hannes F.; Fagnoni, Maurizio; Djuric, Stevan W.

    2018-01-01

    Abstract A mild and selective C(sp3)−H aerobic oxidation enabled by decatungstate photocatalysis has been developed. The reaction can be significantly improved in a microflow reactor enabling the safe use of oxygen and enhanced irradiation of the reaction mixture. Our method allows for the oxidation of both activated and unactivated C−H bonds (30 examples). The ability to selectively oxidize natural scaffolds, such as (−)‐ambroxide, pregnenolone acetate, (+)‐sclareolide, and artemisinin, exemplifies the utility of this new method. PMID:29451725

  18. Strategies to determine diversity, growth, and activity of ammonia-oxidizing archaea in soil.

    PubMed

    Nicol, Graeme W; Prosser, James I

    2011-01-01

    Ecological studies of soil microorganisms require reliable techniques for assessment of microbial community composition, abundance, growth, and activity. Soil structure and physicochemical properties seriously limit the applicability and value of methods involving direct observation, and ecological studies have focused on communities and populations, rather than single cells or microcolonies. Although ammonia-oxidizing archaea were discovered 5 years ago, there are still no cultured representatives from soil and there remains a lack of knowledge regarding their genomic composition, physiology, or functional diversity. Despite these limitations, however, significant insights into their distribution, growth characteristics, and metabolism have been made through the use of a range of molecular methodologies. As well as the analysis of taxonomic markers such as 16S rRNA genes, the development of PCR primers based on a limited number of (mostly marine) sequences has enabled the analysis of homologues encoding proteins involved in energy and carbon metabolism. This chapter will highlight the range of molecular methodologies available for examining the diversity, growth, and activity of ammonia-oxidizing archaea in the soil environment. Copyright © 2011 Elsevier Inc. All rights reserved.

  19. Effect of temperature and dissolved oxygen on biological nitrification at high ammonia concentrations.

    PubMed

    Weon, S Y; Lee, S I; Koopman, B

    2004-11-01

    Effect of temperature and dissolved oxygen concentration on nitrification rate were investigated with enrichment cultures of nitrifying bacteria. Values of specific nitrite oxidation rate in the absence of ammonia were 2.9-12 times higher than maximum specific ammonia oxidation rates at the same temperatures. The presence of high ammonia levels reversed this relationship, causing maximum specific nitrite oxidation rates to fall to 19 to 45% as high as maximum specific ammonia oxidation rates. This result suggests that nitrification at high ammonia levels will invariably result in nitrite accumulation. The K(O2) for nitrite oxidation in the presence of high ammonia levels was higher than the K(O2) for ammonia oxidation when temperature exceeded 18 degrees C, whereas the opposite was true at lower temperatures. These results indicate that low oxygen tensions will exacerbate nitrite accumulation when water temperature is high.

  20. Removal of ammonia from urine vapor by a dual-catalyst system

    NASA Technical Reports Server (NTRS)

    Budininkas, P.

    1977-01-01

    The feasibility of removing ammonia from urine vapor by a low-temperature dual-catalyst system has been demonstrated. The process is based on the catalytic oxidation of ammonia to a mixture of nitrogen, nitrous oxide, and water, followed by a catalytic decomposition of the nitrous oxide into its elements. Potential ammonia oxidation and nitrous oxide decomposition catalysts were first screened with artificial gas mixtures, then tested with the actual urine vapor produced by boiling untreated urine. A suitable dual-catalyst bed arrangement was found that achieved the removal of ammonia and also organic carbon, and recovered water of good quality from urine vapor.

  1. Seasonal Dynamics of Particle-Associated Ammonia-Oxidizing Archaea in Monterey Bay, CA

    NASA Astrophysics Data System (ADS)

    Powell, D. R.; Tolar, B. B.; Francis, C.

    2016-12-01

    Within the past decade, significant research has shed light on key players within the nitrogen cycle. Ammonia-oxidizing Archaea (AOA) were discovered and found to be more abundant than ammonia-oxidizing Bacteria in marine systems, and therefore play a vital role in ammonia oxidation, the rate-limiting step in nitrification that converts NH3 to NO2-. Here we investigated seasonal dynamics of particle-associated (> 10 µm) AOA within Monterey Bay at Station M1 over a year-long sampling period from May 2015 to February 2016. We used quantitative PCR to amplify the archaeal amoA gene and collect data on the abundance of this gene at various depths (5-500 m). Our results indicate that particle-associated AOA are found throughout the upper water column in Monterey Bay, with archaeal amoA gene abundances ranging from 3.9 x 101 to 1.0 x 104 copies/L, with an average of 1.7 x 103 copies/L. Seasonal trends indicate that gene abundance is higher during the winter than in summer. We also quantified `shallow' versus `deep' ecotypes of water column AOA (WCA and WCB, respectively. These data will be compared to environmental data (temperature, salinity, chlorophyll a, etc.) collected during sampling. In comparison to the 0.2µm samples analyzed (mean = 2.2 x 107 copies/L; range = 2.4 x 104 to 1.1 x 108 copies/L), particle-associated archaeal amoA genes were on average 0.01% of the 0.2-10 µm size fraction. Although relatively small, the combined total abundance between the two size fractions may lead to additional correlations. Overall, particle-associated AOA may be important indicators of changing environmental conditions and provide seasonal context into abundance and distribution of these AOA. We also suggest that it may be a useful practice to analyze prefilters for AOA, as particle-associated AOA may contribute significantly to gene abundance estimates and possibly correlations with nitrification rates.

  2. Nitrogen Cycling and Community Structure of Proteobacterial β-Subgroup Ammonia-Oxidizing Bacteria within Polluted Marine Fish Farm Sediments

    PubMed Central

    McCaig, Allison E.; Phillips, Carol J.; Stephen, John R.; Kowalchuk, George A.; Harvey, S. Martyn; Herbert, Rodney A.; Embley, T. Martin; Prosser, James I.

    1999-01-01

    A multidisciplinary approach was used to study the effects of pollution from a marine fish farm on nitrification rates and on the community structure of ammonia-oxidizing bacteria in the underlying sediment. Organic content, ammonium concentrations, nitrification rates, and ammonia oxidizer most-probable-number counts were determined in samples of sediment collected from beneath a fish cage and on a transect at 20 and 40 m from the cage. The data suggest that nitrogen cycling was significantly disrupted directly beneath the fish cage, with inhibition of nitrification and denitrification. Although visual examination indicated some slight changes in sediment appearance at 20 m, all other measurements were similar to those obtained at 40 m, where the sediment was considered pristine. The community structures of proteobacterial β-subgroup ammonia-oxidizing bacteria at the sampling sites were compared by PCR amplification of 16S ribosomal DNA (rDNA), using primers which target this group. PCR products were analyzed by denaturing gradient gel electrophoresis (DGGE) and with oligonucleotide hybridization probes specific for different ammonia oxidizers. A DGGE doublet observed in PCR products from the highly polluted fish cage sediment sample was present at a lower intensity in the 20-m sample but was absent from the pristine 40-m sample station. Band migration, hybridization, and sequencing demonstrated that the doublet corresponded to a marine Nitrosomonas group which was originally observed in 16S rDNA clone libraries prepared from the same sediment samples but with different PCR primers. Our data suggest that this novel Nitrosomonas subgroup was selected for within polluted fish farm sediments and that the relative abundance of this group was influenced by the extent of pollution. PMID:9872782

  3. Response of ammonia oxidizing bacteria and archaea to acute zinc stress and different moisture regimes in soil.

    PubMed

    Vasileiadis, Sotirios; Coppolecchia, Damiano; Puglisi, Edoardo; Balloi, Annalisa; Mapelli, Francesca; Hamon, Rebecca E; Daffonchio, Daniele; Trevisan, Marco

    2012-11-01

    Ammonia oxidation has been intensively studied for its sensitivity to environmental shifts and stresses. However, acute stress effects on the occurrence and composition of ammonia oxidizing bacteria (AOB) and archaea (AOA) based on expression of related molecular markers in complex soil environments have been to an extent overlooked, particularly concerning transient but commonly occurring environmental changes like soil moisture shifts. The present study investigates the responses of AOB and AOA to moisture shifts and high Zn soil content. AmoA gene copies and transcripts of AOB and AOA along with potential nitrification activity were measured in a soil microcosm approach for investigating the referred environmental shifts. Moisture change from 87 to 50 % of the water holding capacity caused a ~99 % reduction of AOB but not of AOA amoA transcripts that did not change significantly. Increasing applied zinc concentrations resulted in a reduction of potential nitrification rates and negatively affected studied gene expressions of both AOB and AOA, with AOB being more responsive. Both 16 S rRNA and amoA transcripts of AOB had an inverse relation to the applied zinc, indicating a gradual loss in total cell activity. Our results suggest the existence of pronounced differences between AOB and AOA concerning ammonia oxidation activity.

  4. Enrichment and Characterization of an Autotrophic Ammonia-Oxidizing Archaeon of Mesophilic Crenarchaeal Group I.1a from an Agricultural Soil▿†

    PubMed Central

    Jung, Man-Young; Park, Soo-Je; Min, Deullae; Kim, Jin-Seog; Rijpstra, W. Irene C.; Sinninghe Damsté, Jaap S.; Kim, Geun-Joong; Madsen, Eugene L.; Rhee, Sung-Keun

    2011-01-01

    Soil nitrification is an important process for agricultural productivity and environmental pollution. Though one cultivated representative of ammonia-oxidizing Archaea from soil has been described, additional representatives warrant characterization. We describe an ammonia-oxidizing archaeon (strain MY1) in a highly enriched culture derived from agricultural soil. Fluorescence in situ hybridization microscopy showed that, after 2 years of enrichment, the culture was composed of >90% archaeal cells. Clone libraries of both 16S rRNA and archaeal amoA genes featured a single sequence each. No bacterial amoA genes could be detected by PCR. A [13C]bicarbonate assimilation assay showed stoichiometric incorporation of 13C into Archaea-specific glycerol dialkyl glycerol tetraethers. Strain MY1 falls phylogenetically within crenarchaeal group I.1a; sequence comparisons to “Candidatus Nitrosopumilus maritimus” revealed 96.9% 16S rRNA and 89.2% amoA gene similarities. Completed growth assays showed strain MY1 to be chemoautotrophic, mesophilic (optimum at 25°C), neutrophilic (optimum at pH 6.5 to 7.0), and nonhalophilic (optimum at 0.2 to 0.4% salinity). Kinetic respirometry assays showed that strain MY1's affinities for ammonia and oxygen were much higher than those of ammonia-oxidizing bacteria (AOB). The yield of the greenhouse gas N2O in the strain MY1 culture was lower but comparable to that of soil AOB. We propose that this new soil ammonia-oxidizing archaeon be designated “Candidatus Nitrosoarchaeum koreensis.” PMID:22003023

  5. Treatment of high strength distillery wastewater (cherry stillage) by integrated aerobic biological oxidation and ozonation.

    PubMed

    Beltrán, F J; Alvarez, P M; Rodríguez, E M; García-Araya, J F; Rivas, J

    2001-01-01

    The performance of integrated aerobic digestion and ozonation for the treatment of high strength distillery wastewater (i.e., cherry stillage) is reported. Experiments were conducted in laboratory batch systems operating in draw and fill mode. For the biological step, activated sludge from a municipal wastewater treatment facility was used as inoculum, showing a high degree of activity to distillery wastewater. Thus, BOD and COD overall conversions of 95% and 82% were achieved, respectively. However, polyphenol content and absorbance at 254 nm (A(254)) could not be reduced more than 35% and 15%, respectively, by means of single biological oxidation. By considering COD as substrate, the aerobic digestion process followed a Contois' model kinetics, from which the maximum specific growth rate of microorganisms (mu(max)) and the inhibition factor, beta, were then evaluated at different conditions of temperature and pH. In the combined process, the effect of a post-ozonation stage was studied. The main goals achieved by the ozonation step were the removal of polyphenols and A(254). Therefore, ozonation was shown to be an appropriate technology to aid aerobic biological oxidation in the treatment of cherry stillage.

  6. pH as a Driver for Ammonia-Oxidizing Archaea in Forest Soils.

    PubMed

    Stempfhuber, Barbara; Engel, Marion; Fischer, Doreen; Neskovic-Prit, Ganna; Wubet, Tesfaye; Schöning, Ingo; Gubry-Rangin, Cécile; Kublik, Susanne; Schloter-Hai, Brigitte; Rattei, Thomas; Welzl, Gerhard; Nicol, Graeme W; Schrumpf, Marion; Buscot, Francois; Prosser, James I; Schloter, Michael

    2015-05-01

    In this study, we investigated the impact of soil pH on the diversity and abundance of archaeal ammonia oxidizers in 27 different forest soils across Germany. DNA was extracted from topsoil samples, the amoA gene, encoding ammonia monooxygenase, was amplified; and the amplicons were sequenced using a 454-based pyrosequencing approach. As expected, the ratio of archaeal (AOA) to bacterial (AOB) ammonia oxidizers' amoA genes increased sharply with decreasing soil pH. The diversity of AOA differed significantly between sites with ultra-acidic soil pH (<3.5) and sites with higher pH values. The major OTUs from soil samples with low pH could be detected at each site with a soil pH <3.5 but not at sites with pH >4.5, regardless of geographic position and vegetation. These OTUs could be related to the Nitrosotalea group 1.1 and the Nitrososphaera subcluster 7.2, respectively, and showed significant similarities to OTUs described from other acidic environments. Conversely, none of the major OTUs typical of sites with a soil pH >4.6 could be found in the ultra- and extreme acidic soils. Based on a comparison with the amoA gene sequence data from a previous study performed on agricultural soils, we could clearly show that the development of AOA communities in soils with ultra-acidic pH (<3.5) is mainly triggered by soil pH and is not influenced significantly by the type of land use, the soil type, or the geographic position of the site, which was observed for sites with acido-neutral soil pH.

  7. The effect of ammonia on canine polymorphonuclear cells.

    PubMed

    Breheny, Craig R; Mellanby, Richard J; Hamilton, Julie A; Gow, Adam G

    2018-06-24

    Hyperammonaemia is a common complication of liver disease in dogs. High concentrations of ammonia can be detrimental to dogs with liver disease for several reasons, notably by causing hepatic encephalopathy (HE) which describes the wide range of neurological abnormalities ranging from altered behaviour to seizures that are well recognised complications in dogs with hepatic disorders. In human patients with liver disease, hyperammonaemia has also been linked to the development of other systemic complications such as dysregulation of the innate immune system. In contrast, the effects of hyperammonaemia on the canine innate immune system is currently unknown. The aim of this study was to investigate the effects of ammonia on the oxidative burst activity of canine polymorphonuclear cells in vitro. Blood obtained from healthy dogs (n = 8) was incubated with escalating concentrations of ammonia ranging from 0 to 250 μM, and the percentage of cells experiencing an oxidative burst was evaluated using a commercial kit (Phagoburst™) and flow cytometry. The spontaneous oxidative burst was evaluated without stimulation and also following stimulation with E coli. The pH of the blood was also measured at the differing ammonia concentrations. There was an increase in the percentage of cells experiencing a spontaneous oxidative burst from ammonia concentrations of 125 μM (p = <0.05) and above (p = <0.01), with a 4.9 fold increase at 200 μM (p = < 0.001). In those cells stimulated with E coli, incubation with increasing ammonia concentrations did not result in a significant difference in oxidative burst from baseline (p = 0.953). There was no statistically significant difference between the pH of the blood at the various ammonia concentrations (p = 0.2) suggesting that the difference in spontaneous oxidative burst was due to the ammonia rather than simply a change in pH conditions. In summary, the spontaneous oxidative burst of neutrophils was

  8. [Effects of continuous cropping of vegetables on ammonia oxidizers community structure].

    PubMed

    Meng, De-Long; Yang, Yang; Wu, Yan-Zheng; Wu, Min-Na; Qin, Hong-Ling; Zhu, Yi-Jun; Wei, Wen-Xue

    2012-04-01

    Investigations were conducted on the effects of intensive application of chemical fertilizers in crop production on soil nitrifier communities and the relationship between nitrifier communities and soil nitrification ability. Two series of vegetable soils were selected from Huangxing, Changsha, reflecting continuous vegetable cropping with about 20 years and new vegetable field with only about 2 years vegetable growing history. In each series five independent topsoils (0-20 cm) were sampled and each soil was a mixture of 10 cores randomly taken in the same field. Terminal restriction fragment length polymorphism (T-RFLP) and quantity PCR (Q-PCR) were used to determine the composition and abundance of ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) communities. Results indicated that long-term and continuous vegetable cropping obviously changed the compositions of both AOB and AOA amoA gene, soil pH and Olsen-P content were the dominant factors affecting the composition of AOB amoA. In the vegetable soils, although the copy number of AOA amoA gene was about 5 times higher than AOB amoA gene, no significant correlation was detected between AOA amoA gene abundance and soil nitrification rate. It was not sure whether long-term and continuous vegetable cropping could shift the abundance of AOB and AOA, but it resulted in the enrichment of some dominant AOB species and increase of soil nitrification potential (PNF).

  9. Activity-Based Protein Profiling of Ammonia Monooxygenase in Nitrosomonas europaea

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bennett, Kristen; Sadler, Natalie C.; Wright, Aaron T.

    Nitrosomonas europaeais an aerobic nitrifying bacterium that oxidizes ammonia (NH 3) to nitrite (NO 2 ₋) through the sequential activities of ammonia monooxygenase (AMO) and hydroxylamine dehydrogenase (HAO). Many alkynes are mechanism-based inactivators of AMO, and here we describe an activity-based protein profiling method for this enzyme using 1,7-octadiyne (17OD) as a probe. Inactivation of NH 4 +-dependent O 2uptake byN. europaeaby 17OD was time- and concentration-dependent. The effects of 17OD were specific for ammonia-oxidizing activity, andde novoprotein synthesis was required to reestablish this activity after cells were exposed to 17OD. Cells were reacted with Alexa Fluor 647 azide usingmore » a copper-catalyzed azide-alkyne cycloaddition (CuAAC) (click) reaction, solubilized, and analyzed by SDS-PAGE and infrared (IR) scanning. A fluorescent 28-kDa polypeptide was observed for cells previously exposed to 17OD but not for cells treated with either allylthiourea or acetylene prior to exposure to 17OD or for cells not previously exposed to 17OD. The fluorescent polypeptide was membrane associated and aggregated when heated with β-mercaptoethanol and SDS. The fluorescent polypeptide was also detected in cells pretreated with other diynes, but not in cells pretreated with structural homologs containing a single ethynyl functional group. The membrane fraction from 17OD-treated cells was conjugated with biotin-azide and solubilized in SDS. Streptavidin affinity-purified polypeptides were on-bead trypsin-digested, and amino acid sequences of the peptide fragments were determined by liquid chromatography-mass spectrometry (LC-MS) analysis. Peptide fragments from AmoA were the predominant peptides detected in 17OD-treated samples. In-gel digestion and matrix-assisted laser desorption ionization–tandem time of flight (MALDI-TOF/TOF) analyses also confirmed that the fluorescent 28-kDa polypeptide was AmoA.« less

  10. Activity-Based Protein Profiling of Ammonia Monooxygenase in Nitrosomonas europaea

    PubMed Central

    Bennett, Kristen; Sadler, Natalie C.; Wright, Aaron T.; Yeager, Chris

    2016-01-01

    Nitrosomonas europaea is an aerobic nitrifying bacterium that oxidizes ammonia (NH3) to nitrite (NO2−) through the sequential activities of ammonia monooxygenase (AMO) and hydroxylamine dehydrogenase (HAO). Many alkynes are mechanism-based inactivators of AMO, and here we describe an activity-based protein profiling method for this enzyme using 1,7-octadiyne (17OD) as a probe. Inactivation of NH4+-dependent O2 uptake by N. europaea by 17OD was time- and concentration-dependent. The effects of 17OD were specific for ammonia-oxidizing activity, and de novo protein synthesis was required to reestablish this activity after cells were exposed to 17OD. Cells were reacted with Alexa Fluor 647 azide using a copper-catalyzed azide-alkyne cycloaddition (CuAAC) (click) reaction, solubilized, and analyzed by SDS-PAGE and infrared (IR) scanning. A fluorescent 28-kDa polypeptide was observed for cells previously exposed to 17OD but not for cells treated with either allylthiourea or acetylene prior to exposure to 17OD or for cells not previously exposed to 17OD. The fluorescent polypeptide was membrane associated and aggregated when heated with β-mercaptoethanol and SDS. The fluorescent polypeptide was also detected in cells pretreated with other diynes, but not in cells pretreated with structural homologs containing a single ethynyl functional group. The membrane fraction from 17OD-treated cells was conjugated with biotin-azide and solubilized in SDS. Streptavidin affinity-purified polypeptides were on-bead trypsin-digested, and amino acid sequences of the peptide fragments were determined by liquid chromatography-mass spectrometry (LC-MS) analysis. Peptide fragments from AmoA were the predominant peptides detected in 17OD-treated samples. In-gel digestion and matrix-assisted laser desorption ionization–tandem time of flight (MALDI-TOF/TOF) analyses also confirmed that the fluorescent 28-kDa polypeptide was AmoA. PMID:26826234

  11. Response of ammonia oxidizing archaea and bacteria to decabromodiphenyl ether and copper contamination in river sediments.

    PubMed

    Wang, Linqiong; Li, Yi; Niu, Lihua; Zhang, Wenlong; Zhang, Huanjun; Wang, Longfei; Wang, Peifang

    2018-01-01

    Ammonia oxidation plays a fundamental role in river nitrogen cycling ecosystems, which is normally governed by both ammonia oxidizing archaea (AOA) and ammonia oxidizing bacteria (AOB). Co-contamination of typical emerging pollutant Polybrominated diphenyl ethers (PBDEs) and heavy metal on AOA and AOB communities in river sediments remains unknown. In this study, multiple analytical tools, including high-throughput pyrosequencing and real-time quantitative PCR (qPCR), were used to reveal the ammonia monooxygenase (AMO) activity, subunit alpha (amoA) gene abundance, and community structures of AOA and AOB in river sediments. It was found that the inhibition of AMO activities was increased with the increase of decabromodiphenyl ether (BDE 209, 1-100 mg kg -1 ) and copper (Cu, 50-500 mg kg -1 ) concentrations. Moreover, the synergic effects of BDE 209 and Cu resulted in a higher AMO activity reduction than the individual pollutant BDE 209. The AOA amoA copy number declined by 75.9% and 83.2% and AOB amoA gene abundance declined 82.8% and 90.0% at 20 and 100 mg kg -1 BDE 209 with a 100 mg kg -1 Cu co-contamination, respectively. The pyrosequencing results showed that both AOB and AOA community structures were altered, with a higher change of AOB than that of AOA. The results demonstrated that the AOB microbial community may be better adapted to BDE 209 and Cu pollution, while AOA might possess a greater capacity for stress resistance. Our study provides a better understanding of the ecotoxicological effects of heavy metal and micropollutant combined exposure on AOA and AOB in river sediments. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Abundance and diversity of ammonia-oxidizing archaea and bacteria in the rhizosphere soil of three plants in the Ebinur Lake wetland.

    PubMed

    He, Yuan; Hu, Wenge; Ma, Decao; Lan, Hongzhu; Yang, Yang; Gao, Yan

    2017-07-01

    Ammonia oxidation is carried out by ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA). The Ebinur Lake wetland is the best example of a temperate arid zone wetland ecosystem in China. Soil samples were collected from rhizosphere and non-rhizosphere soil containing Halocnemum strobilaceum (samples H and H'), Phragmites australis (samples R and R'), and Karelinia caspia (samples K and K') to study the relationship between environmental factors and the community structure of AOB and AOA. Phylogenetic analysis showed that the AOA sequences belonged to the Nitrosopumilus and Nitrososphaera clusters. AOB were grouped into Nitrosospira sp. and Nitrosomonas sp. Quantitative polymerase chain reaction results showed that the AOA abundance ranged from 2.09 × 10 4 to 2.94 × 10 5 gene copies/g soil. The highest number of AOA was detected in sample K, followed by samples R and H. AOB abundance varied between 2.91 × 10 5 and 1.05 × 10 6 gene copies/g soil, which was higher than that of AOA. Redundancy analysis indicated that electrical conductivity, pH, and NH 4 + -N might influence the community structure of AOA and AOB. AOB might play a more crucial role than AOA in ammonia oxidation based on AOB's higher diversity and abundance in the Ebinur Lake wetland in Xinjiang.

  13. The one-stage autothermal thermophilic aerobic digestion for sewage sludge treatment: stabilization process and mechanism.

    PubMed

    Liu, Shugen; Zhu, Nanwen; Li, Loretta Y

    2012-01-01

    Batch experiment was carried out in a simulated thermophilic aerobic digester to investigate the digestion process of one-stage autothermal thermophilic aerobic digester and to explore the sludge stabilization mechanism. Volatile solids removal was 38.4% at 408 h and 45.0% at 552 h. Chemical oxidation demand, total nitrogen, and ammonia nitrogen in supernatant increased rapidly up to 168 h, and all of them fluctuated moderately after 360 h. Volatile fatty acid (VFA) accumulated rapidly up to 24 to 168 h, then declined sharply, reaching a low concentration after 312 h. Propionic, iso-valeric, and iso-butyric acids, in addition to acetic acids, were also the major components of VFA. As the biochemical metabolic process was inhibited under oxygen-deficiency condition, the digestion system can produce acetic, propionic, butyric acids and other VFA constituents to meet the demand for NAD(+) and maximize ATP generation. The ORP affected the VFA production and depletion as well as sulfate levels. Copyright © 2011 Elsevier Ltd. All rights reserved.

  14. Ammonia chemistry in a flameless jet

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zieba, Mariusz; Schuster, Anja; Scheffknecht, Guenter

    2009-10-15

    In this paper, the nitrogen chemistry in an ammonia (NH{sub 3}) doped flameless jet is investigated using a kinetic reactor network model. The reactor network model is used to explain the main differences in ammonia chemistry for methane (CH{sub 4})-containing fuels and methane-free fuels. The chemical pathways of nitrogen oxides (NO{sub x}) formation and destruction are identified using rate-of-production analysis. The results show that in the case of natural gas, ammonia reacts relatively late at fuel lean condition leading to high NO{sub x} emissions. In the pre-ignition zone, the ammonia chemistry is blocked due to the absence of free radicalsmore » which are consumed by methane-methyl radical (CH{sub 3}) conversion. In the case of methane-free gas, the ammonia reacted very rapidly and complete decomposition was reached in the fuel rich region of the jet. In this case the necessary radicals for the ammonia conversion are generated from hydrogen (H{sub 2}) oxidation. (author)« less

  15. Continuous Flow Aerobic Alcohol Oxidation Reactions Using a Heterogeneous Ru(OH)x/Al2O3 Catalyst

    PubMed Central

    2015-01-01

    Ru(OH)x/Al2O3 is among the more versatile catalysts for aerobic alcohol oxidation and dehydrogenation of nitrogen heterocycles. Here, we describe the translation of batch reactions to a continuous-flow method that enables high steady-state conversion and single-pass yields in the oxidation of benzylic alcohols and dehydrogenation of indoline. A dilute source of O2 (8% in N2) was used to ensure that the reaction mixture, which employs toluene as the solvent, is nonflammable throughout the process. A packed bed reactor was operated isothermally in an up-flow orientation, allowing good liquid–solid contact. Deactivation of the catalyst during the reaction was modeled empirically, and this model was used to achieve high conversion and yield during extended operation in the aerobic oxidation of 2-thiophene methanol (99+% continuous yield over 72 h). PMID:25620869

  16. Method for forming ammonia

    DOEpatents

    Kong, Peter C.; Pink, Robert J.; Zuck, Larry D.

    2008-08-19

    A method for forming ammonia is disclosed and which includes the steps of forming a plasma; providing a source of metal particles, and supplying the metal particles to the plasma to form metal nitride particles; and providing a substance, and reacting the metal nitride particles with the substance to produce ammonia, and an oxide byproduct.

  17. Mechanism of Copper(I)/TEMPO-Catalyzed Aerobic Alcohol Oxidation

    PubMed Central

    Hoover, Jessica M.; Ryland, Bradford L.; Stahl, Shannon S.

    2013-01-01

    Homogeneous Cu/TEMPO catalyst systems (TEMPO = 2,2,6,6-tetramethylpiperidine-N-oxyl) have emerged as some of the most versatile and practical catalysts for aerobic alcohol oxidation. Recently, we disclosed a (bpy)CuI/TEMPO/NMI catalyst system (NMI = N-methylimidazole) that exhibits fast rates and high selectivities, even with unactivated aliphatic alcohols. Here, we present a mechanistic investigation of this catalyst system, in which we compare the reactivity of benzylic and aliphatic alcohols. This work includes analysis of catalytic rates by gas-uptake and in situ IR kinetic methods and characterization of the catalyst speciation during the reaction by EPR and UV–visible spectroscopic methods. The data support a two-stage catalytic mechanism consisting of (1) “catalyst oxidation” in which CuI and TEMPO–H are oxidized by O2 via a binuclear Cu2O2 intermediate and (2) “substrate oxidation” mediated by CuII and the nitroxyl radical of TEMPO via a CuII-alkoxide intermediate. Catalytic rate laws, kinetic isotope effects, and spectroscopic data show that reactions of benzylic and aliphatic alcohols have different turnover-limiting steps. Catalyst oxidation by O2 is turnover limiting with benzylic alcohols, while numerous steps contribute to the turnover rate in the oxidation of aliphatic alcohols. PMID:23317450

  18. Techno-economic evaluation of the application of ozone-oxidation in a full-scale aerobic digestion plant.

    PubMed

    Chiavola, Agostina; D'Amato, Emilio; Gori, Riccardo; Lubello, Claudio; Sirini, Piero

    2013-04-01

    This paper deals with the application of the ozone-oxidation in a full scale aerobic sludge digester. Ozonation was applied continuously to a fraction of the biological sludge extracted from the digestion unit; the ozonated sludge was then recirculated to the same digester. Three different ozone flow rates were tested (60,500 and 670g O3 h(-1)) and their effects evaluated in terms of variation of the total and soluble fractions of COD, nitrogen and phosphorous, of total and volatile suspended solids concentrations and Sludge Volume Index in the aerobic digestion unit. During the 7-month operation of the ozonation process, it was observed an appreciable improvement of the aerobic digestion efficiency (up to about 20% under the optimal conditions) and of the sludge settleability properties. These results determined an average reduction of about 60% in the biological sludge extracted from the plant and delivered to final disposal. A thorough economic analysis showed that this reduction allowed to achieve a significant cost saving for the plant with respect to the previous years operated without ozonation. Furthermore, it was determined the threshold disposal cost above which implementation of the ozone oxidation in the aerobic digestion units of similar WWTPs becomes economically convenient (about 60€t(-1) of sludge). Copyright © 2013 Elsevier Ltd. All rights reserved.

  19. The influence of land use on the abundance and diversity of ammonia oxidizers.

    PubMed

    Zhao, Dayong; Luo, Juan; Wang, Jianqun; Huang, Rui; Guo, Kun; Li, Yi; Wu, Qinglong L

    2015-02-01

    Nitrification plays a significant role in soil nitrogen cycling, a process in which the first step can be catalyzed by ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB). In this study, six soil samples with distinct land-use regimes (forestland soil, paddy soil, wheat-planted soil, fruit-planted soil, grassland soil, and rape-planted soil) were collected from Chuzhou city in the Anhui province to elucidate the effects of land use on the abundance and diversity of AOA and AOB. The abundance of the archaeal amoA gene ranged from 2.12 × 10(4) copies per gram of dry soil to 2.57 × 10(5) copies per gram of dry soil, while the abundance of the bacterial amoA gene ranged from 5.58 × 10(4) copies per gram of dry soil to 1.59 × 10(8) copies per gram of dry soil. The grassland and the rape-planted soil samples maintained the highest abundance of the bacterial and archaeal amoA genes, respectively. The abundance of the archaeal amoA gene was positively correlated with the pH (P < 0.05). The ammonia concentrations exhibited a significantly positive relation with the abundance of the bacterial amoA gene (P < 0.01) and the number of OTUs of AOB (P < 0.05). The community composition of AOB was more sensitive to the land-use regimes than that of AOA. The data obtained in this study may be useful to better understand the nitrification process in soils with different land-use regimes.

  20. Population and community structure shifts of ammonia oxidizers after four-year successive biochar application to agricultural acidic and alkaline soils.

    PubMed

    He, Lili; Bi, Yucui; Zhao, Jin; Pittelkow, Cameron M; Zhao, Xu; Wang, Shenqiang; Xing, Guangxi

    2018-04-01

    Long-term studies that advance our mechanistic understanding of biochar (BC)‑nitrogen (N) interactions in agricultural soils are lacking. In this study, soil potential nitrification rates (PNR), the abundance and composition of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) communities following 4-year of BC application were investigated using the shaken-slurry procedure and molecular sequencing techniques for an acidic Oxisol (QU) and an alkaline Cambisol (YU). Soils were obtained from an outdoor soil column experiment with straw-BC application rates of 0 (BC0), 2.25 (BC2.25) and 11.3 (BC11.3) Mgha -1 per cropping season for eight consecutive wheat/millet seasons. Quantitative polymerase chain reaction (qPCR) and 454 high-throughput pyrosequencing techniques were performed to quantify and sequence amoA gene copies and composition of AOA and AOB. Results showed that QU had lower PNR and a higher ratio of amoA gene copies of AOA to AOB than YU, PNR of QU with BC application was significantly associated with the amoA gene of AOB. Similar to previous short-term findings, BC application enhanced QU soil nitrification, which may be explained by the significant increase in AOB abundance and a shift in AOB community structure from Nitrosospira cluster 2 toward cluster 3, along with the disappearance of some obligate acidophile AOA groups, leading to the appearance of ammonia-oxidizers from neutral-alkaline soils in BC-amended acid soils. Canonical correspondence analysis (CCA) showed that soil pH was the most important factor driving shifts in ammonia-oxidizers composition. Although BC application did not have significant effects on PNR in YU, BC11.3 decreased AOA and AOB gene copies and influenced the relative abundance of community structure. Our findings represent the first investigation of long-term BC effects on AOA and AOB communities in agricultural soils using 454 high-throughput pyrosequencing, showing that BC application can alter soil

  1. Mn-Catalyzed Highly Efficient Aerobic Oxidative Hydroxyazidation of Olefins: A Direct Approach to β-Azido Alcohols.

    PubMed

    Sun, Xiang; Li, Xinyao; Song, Song; Zhu, Yuchao; Liang, Yu-Feng; Jiao, Ning

    2015-05-13

    An efficient Mn-catalyzed aerobic oxidative hydroxyazidation of olefins for synthesis of β-azido alcohols has been developed. The aerobic oxidative generation of azido radical employing air as the terminal oxidant is disclosed as the key process for this transformation. The reaction is appreciated by its broad substrate scope, inexpensive Mn-catalyst, high efficiency, easy operation under air, and mild conditions at room temperature. This chemistry provides a novel approach to high value-added β-azido alcohols, which are useful precursors of aziridines, β-amino alcohols, and other important N- and O-containing heterocyclic compounds. This chemistry also provides an unexpected approach to azido substituted cyclic peroxy alcohol esters. A DFT calculation indicates that Mn catalyst plays key dual roles as an efficient catalyst for the generation of azido radical and a stabilizer for peroxyl radical intermediate. Further calculation reasonably explains the proposed mechanism for the control of C-C bond cleavage or for the formation of β-azido alcohols.

  2. Anaerobic ammonia removal in presence of organic matter: a novel route.

    PubMed

    Sabumon, P C

    2007-10-01

    This study describes the feasibility of anaerobic ammonia removal process in presence of organic matter. Different sources of biomass collected from diverse eco-systems containing ammonia and organic matter (OM) were screened for potential anaerobic ammonia removal. Sequential batch studies confirmed the possibility of anaerobic ammonia removal in presence of OM, but ammonia was oxidized anoxically to nitrate (at oxidation reduction potential; ORP=-248+/-25 mV) by an unknown mechanism unlike in the reported anammox process. The oxygen required for oxidation of ammonia might have been generated through catalase enzymatic activity of facultative anaerobes in mixed culture. The oxygen generation possibility by catalase enzyme route was demonstrated. Among the inorganic electron acceptors (NO(2)(-), NO(3)(-) and SO(4)(2-)) studied, NO(2)(-) was found to be most effective in total nitrogen removal. Denitrification by the developed culture was much effective and faster compared to ammonia oxidation. The results of this study show that anaerobic ammonia removal is feasible in presence of OM. The novel nitrogen removal route is hypothesized as enzymatic anoxic oxidation of NH(4)(+) to NO(3)(-), followed by denitrification via autotrophic and/or heterotrophic routes. The results of batch study were confirmed in continuous reactor operation.

  3. Genome of a Low-Salinity Ammonia-Oxidizing Archaeon Determined by Single-Cell and Metagenomic Analysis

    PubMed Central

    Potanina, Anastasia; Francis, Christopher A.; Quake, Stephen R.

    2011-01-01

    Ammonia-oxidizing archaea (AOA) are thought to be among the most abundant microorganisms on Earth and may significantly impact the global nitrogen and carbon cycles. We sequenced the genome of AOA in an enrichment culture from low-salinity sediments in San Francisco Bay using single-cell and metagenomic genome sequence data. Five single cells were isolated inside an integrated microfluidic device using laser tweezers, the cells' genomic DNA was amplified by multiple displacement amplification (MDA) in 50 nL volumes and then sequenced by high-throughput DNA pyrosequencing. This microscopy-based approach to single-cell genomics minimizes contamination and allows correlation of high-resolution cell images with genomic sequences. Statistical properties of coverage across the five single cells, in combination with the contrasting properties of the metagenomic dataset allowed the assembly of a high-quality draft genome. The genome of this AOA, which we designate Candidatus Nitrosoarchaeum limnia SFB1, is ∼1.77 Mb with >2100 genes and a G+C content of 32%. Across the entire genome, the average nucleotide identity to Nitrosopumilus maritimus, the only AOA in pure culture, is ∼70%, suggesting this AOA represents a new genus of Crenarchaeota. Phylogenetically, the 16S rRNA and ammonia monooxygenase subunit A (amoA) genes of this AOA are most closely related to sequences reported from a wide variety of freshwater ecosystems. Like N. maritimus, the low-salinity AOA genome appears to have an ammonia oxidation pathway distinct from ammonia oxidizing bacteria (AOB). In contrast to other described AOA, these low-salinity AOA appear to be motile, based on the presence of numerous motility- and chemotaxis-associated genes in the genome. This genome data will be used to inform targeted physiological and metabolic studies of this novel group of AOA, which may ultimately advance our understanding of AOA metabolism and their impacts on the global carbon and nitrogen cycles. PMID

  4. Genome of a low-salinity ammonia-oxidizing archaeon determined by single-cell and metagenomic analysis.

    PubMed

    Blainey, Paul C; Mosier, Annika C; Potanina, Anastasia; Francis, Christopher A; Quake, Stephen R

    2011-02-22

    Ammonia-oxidizing archaea (AOA) are thought to be among the most abundant microorganisms on Earth and may significantly impact the global nitrogen and carbon cycles. We sequenced the genome of AOA in an enrichment culture from low-salinity sediments in San Francisco Bay using single-cell and metagenomic genome sequence data. Five single cells were isolated inside an integrated microfluidic device using laser tweezers, the cells' genomic DNA was amplified by multiple displacement amplification (MDA) in 50 nL volumes and then sequenced by high-throughput DNA pyrosequencing. This microscopy-based approach to single-cell genomics minimizes contamination and allows correlation of high-resolution cell images with genomic sequences. Statistical properties of coverage across the five single cells, in combination with the contrasting properties of the metagenomic dataset allowed the assembly of a high-quality draft genome. The genome of this AOA, which we designate Candidatus Nitrosoarchaeum limnia SFB1, is ∼1.77 Mb with >2100 genes and a G+C content of 32%. Across the entire genome, the average nucleotide identity to Nitrosopumilus maritimus, the only AOA in pure culture, is ∼70%, suggesting this AOA represents a new genus of Crenarchaeota. Phylogenetically, the 16S rRNA and ammonia monooxygenase subunit A (amoA) genes of this AOA are most closely related to sequences reported from a wide variety of freshwater ecosystems. Like N. maritimus, the low-salinity AOA genome appears to have an ammonia oxidation pathway distinct from ammonia oxidizing bacteria (AOB). In contrast to other described AOA, these low-salinity AOA appear to be motile, based on the presence of numerous motility- and chemotaxis-associated genes in the genome. This genome data will be used to inform targeted physiological and metabolic studies of this novel group of AOA, which may ultimately advance our understanding of AOA metabolism and their impacts on the global carbon and nitrogen cycles.

  5. Beyond benzoin condensation: trimerization of aldehydes via metal-free aerobic oxidative esterification of aldehydes with benzoin products in the presence of cyanide.

    PubMed

    Kim, Yoo-Jin; Kim, Na Yeun; Cheon, Cheol-Hong

    2014-05-02

    An unusual trimerization of aldehydes in the presence of cyanide via metal-free aerobic oxidative esterification under ambient conditions is described. Various aromatic aldehydes provided the corresponding oxidative esterification products in good to excellent yields. Mechanistic studies suggested that this reaction would proceed via a two-step sequence: cyanide-catalyzed benzoin condensation of aldehydes and subsequent aerobic oxidative esterification of aldehydes with the resultant benzoin products. The usefulness of this protocol was further demonstrated by converting the resulting trimeric products into other biologically important compounds.

  6. Thaumarchaeotes abundant in refinery nitrifying sludges express amoA but are not obligate autotrophic ammonia oxidizers

    PubMed Central

    Mußmann, Marc; Brito, Ivana; Pitcher, Angela; Sinninghe Damsté, Jaap S.; Hatzenpichler, Roland; Richter, Andreas; Nielsen, Jeppe L.; Nielsen, Per Halkjær; Müller, Anneliese; Daims, Holger; Wagner, Michael; Head, Ian M.

    2011-01-01

    Nitrification is a core process in the global nitrogen cycle that is essential for the functioning of many ecosystems. The discovery of autotrophic ammonia-oxidizing archaea (AOA) within the phylum Thaumarchaeota has changed our perception of the microbiology of nitrification, in particular since their numerical dominance over ammonia-oxidizing bacteria (AOB) in many environments has been revealed. These and other data have led to a widely held assumption that all amoA-encoding members of the Thaumarchaeota (AEA) are autotrophic nitrifiers. In this study, 52 municipal and industrial wastewater treatment plants were screened for the presence of AEA and AOB. Thaumarchaeota carrying amoA were detected in high abundance only in four industrial plants. In one plant, thaumarchaeotes closely related to soil group I.1b outnumbered AOB up to 10,000-fold, and their numbers, which can only be explained by active growth in this continuous culture system, were two to three orders of magnitude higher than could be sustained by autotrophic ammonia oxidation. Consistently, 14CO2 fixation could only be detected in AOB but not in AEA in actively nitrifying sludge from this plant via FISH combined with microautoradiography. Furthermore, in situ transcription of archaeal amoA, and very weak in situ labeling of crenarchaeol after addition of 13CO2, was independent of the addition of ammonium. These data demonstrate that some amoA-carrying group I.1b Thaumarchaeota are not obligate chemolithoautotrophs. PMID:21930919

  7. Impact of aerobic acclimation on the nitrification performance and microbial community of landfill leachate sludge.

    PubMed

    Hira, Daisuke; Aiko, Nobuyuki; Yabuki, Yoshinori; Fujii, Takao

    2018-03-01

    Nitrogenous pollution of water is regarded as a global environmental problem, and nitrogen removal has become an important issue in wastewater treatment processes. Landfill leachate is a typical large source of nitrogenous wastewater. Although the characteristics of leachate vary according to the age of the landfill, leachates of mature landfill have high concentrations of nitrogenous compounds. Most nitrogen in these leachates is in the form of ammonium nitrogen. In this study, we investigated the bacterial community of sludge from a landfill leachate lagoon by pyrosequencing of the bacterial 16S rRNA gene. The sludge was acclimated in a laboratory-scale reactor with aeration using a mechanical stirrer to promote nitrification. On 149 days, nitrification was achieved and then the bacterial community was also analyzed. The bacterial community was also analyzed after nitrification was achieved. Pyrosequencing analyses revealed that the abundances of ammonia-oxidizing and nitrite-oxidizing bacteria were increased by acclimation and their total proportions increased to >15% of total biomass. Changes in the sulfate-reducing and sulfur-oxidizing bacteria were also observed during the acclimation process. The aerobic acclimation process enriched a nitrifying microbial community from the landfill leachate sludge. These results suggested that the aerobic acclimation is a processing method for the nitrification ammonium oxidizing throw the enrichment of nitrifiers. Improvement of this acclimation method would allow nitrogen removal from leachate by nitrification and sulfur denitrification. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. The emission of volatile compounds during the aerobic and the combined anaerobic/aerobic composting of biowaste

    NASA Astrophysics Data System (ADS)

    Smet, Erik; Van Langenhove, Herman; De Bo, Inge

    Two different biowaste composting techniques were compared with regard to their overall emission of volatile compounds during the active composting period. In the aerobic composting process, the biowaste was aerated during a 12-week period, while the combined anaerobic/aerobic composting process consisted of a sequence of a 3-week anaerobic digestion (phase I) and a 2-week aeration period (phase II). While the emission of volatiles during phase I of the combined anaerobic/aerobic composting process was measured in a full-scale composting plant, the aerobic stages of both composting techniques were performed in pilot-scale composting bins. Similar groups of volatile compounds were analysed in the biogas and the aerobic composting waste gases, being alcohols, carbonyl compounds, terpenes, esters, sulphur compounds and ethers. Predominance of alcohols (38% wt/wt of the cumulative emission) was observed in the exhaust air of the aerobic composting process, while predominance of terpenes (87%) and ammonia (93%) was observed in phases I and II of the combined anaerobic/aerobic composting process, respectively. In the aerobic composting process, 2-propanol, ethanol, acetone, limonene and ethyl acetate made up about 82% of the total volatile organic compounds (VOC)-emission. Next to this, the gas analysis during the aerobic composting process revealed a strong difference in emission profile as a function of time between different groups of volatiles. The total emission of VOC, NH 3 and H 2S during the aerobic composting process was 742 g ton -1 biowaste, while the total emission during phases I and II of the combined anaerobic/aerobic composting process was 236 and 44 g ton -1 biowaste, respectively. Taking into consideration the 99% removal efficiency of volatiles upon combustion of the biogas of phase I in the electricity generator, the combined anaerobic/aerobic composting process can be considered as an attractive alternative for aerobic biowaste composting because of

  9. Competition for ammonia influences the structure of chemotrophic communities in geothermal springs.

    PubMed

    Hamilton, Trinity L; Koonce, Evangeline; Howells, Alta; Havig, Jeff R; Jewell, Talia; de la Torre, José R; Peters, John W; Boyd, Eric S

    2014-01-01

    Source waters sampled from Perpetual Spouter hot spring (pH 7.03, 86.4°C), Yellowstone National Park, WY, have low concentrations of total ammonia, nitrite, and nitrate, suggesting nitrogen (N) limitation and/or tight coupling of N cycling processes. Dominant small-subunit rRNA sequences in Perpetual Spouter source sediments are closely affiliated with the ammonia-oxidizing archaeon "Candidatus Nitrosocaldus yellowstonii" and the putatively nitrogen-fixing (diazotrophic) bacterium Thermocrinis albus, respectively, suggesting that these populations may interact at the level of the bioavailable N pool, specifically, ammonia. This hypothesis was evaluated by using a combination of geochemical, physiological, and transcriptomic analyses of sediment microcosms. Amendment of microcosms with allylthiourea, an inhibitor of ammonia oxidation, decreased rates of acetylene reduction (a proxy for N2 fixation) and nitrite production (a proxy for ammonia oxidation) and decreased transcript levels of structural genes involved in both nitrogen fixation (nifH) and ammonia oxidation (amoA). In contrast, amendment of microcosms with ammonia stimulated nitrite production and increased amoA transcript levels while it suppressed rates of acetylene reduction and decreased nifH transcript levels. Sequencing of amplified nifH and amoA transcripts from native sediments, as well as microcosms, at 2 and 4 h postamendment, indicates that the dominant and responsive populations involved in ammonia oxidation and N2 fixation are closely affiliated with Ca. Nitrosocaldus yellowstonii and T. albus, respectively. Collectively, these results suggest that ammonia-oxidizing archaea, such as Ca. Nitrosocaldus yellowstonii, have an apparent affinity for ammonia that is higher than that of the diazotrophs present in this ecosystem. Depletion of the bioavailable N pool through the activity of ammonia-oxidizing archaea likely represents a strong selective pressure for the inclusion of organisms capable of

  10. Competition for Ammonia Influences the Structure of Chemotrophic Communities in Geothermal Springs

    PubMed Central

    Hamilton, Trinity L.; Koonce, Evangeline; Howells, Alta; Havig, Jeff R.; Jewell, Talia; de la Torre, José R.; Peters, John W.

    2014-01-01

    Source waters sampled from Perpetual Spouter hot spring (pH 7.03, 86.4°C), Yellowstone National Park, WY, have low concentrations of total ammonia, nitrite, and nitrate, suggesting nitrogen (N) limitation and/or tight coupling of N cycling processes. Dominant small-subunit rRNA sequences in Perpetual Spouter source sediments are closely affiliated with the ammonia-oxidizing archaeon “Candidatus Nitrosocaldus yellowstonii” and the putatively nitrogen-fixing (diazotrophic) bacterium Thermocrinis albus, respectively, suggesting that these populations may interact at the level of the bioavailable N pool, specifically, ammonia. This hypothesis was evaluated by using a combination of geochemical, physiological, and transcriptomic analyses of sediment microcosms. Amendment of microcosms with allylthiourea, an inhibitor of ammonia oxidation, decreased rates of acetylene reduction (a proxy for N2 fixation) and nitrite production (a proxy for ammonia oxidation) and decreased transcript levels of structural genes involved in both nitrogen fixation (nifH) and ammonia oxidation (amoA). In contrast, amendment of microcosms with ammonia stimulated nitrite production and increased amoA transcript levels while it suppressed rates of acetylene reduction and decreased nifH transcript levels. Sequencing of amplified nifH and amoA transcripts from native sediments, as well as microcosms, at 2 and 4 h postamendment, indicates that the dominant and responsive populations involved in ammonia oxidation and N2 fixation are closely affiliated with Ca. Nitrosocaldus yellowstonii and T. albus, respectively. Collectively, these results suggest that ammonia-oxidizing archaea, such as Ca. Nitrosocaldus yellowstonii, have an apparent affinity for ammonia that is higher than that of the diazotrophs present in this ecosystem. Depletion of the bioavailable N pool through the activity of ammonia-oxidizing archaea likely represents a strong selective pressure for the inclusion of organisms capable

  11. Magnetically recoverable magnetite/gold catalyst stabilized by poly(N-vinyl-2-pyrrolidone) for aerobic oxidation of alcohols.

    PubMed

    Chen, Hsiao Wei; Murugadoss, Arumugam; Hor, T S Andy; Sakurai, Hidehiro

    2010-12-29

    Fe(3)O(4):PVP/Au nanocomposite synthesized via a two-step procedure was tested as a quasi-homogenous alcohol oxidation catalyst. It was found that the nanocomposite was able to carry out aerobic oxidation of alcohols in water at room temperature. Studies show rapid magnetic recoverability and reusability characteristics.

  12. Study of removal of ammonia from urine vapor by dual catalyst

    NASA Technical Reports Server (NTRS)

    Budininkas, P.

    1976-01-01

    The feasibility of ammonia removal from urine vapor by a low temperature dual-catalyst system was investigated. The process is based on the initial catalytic oxidation of ammonia present in urine vapor to nitrogen and nitrous oxide, followed by a catalytic decomposition of the nitrous oxide formed into its elements. The most active catalysts for the oxidation of ammonia and for the decomposition of N2O, identified in screening tests, were then combined into dual catalyst systems and tested to establish their overall efficiencies for the removal of ammonia from artificial gas mixtures. Dual catalyst systems capable of ammonia removal from the artificial gas mixtures were then tested with the actual urine vapor produced by boiling untreated urine. A suitable dual catalyst bed arrangement was found that achieved the removal of ammonia and organic carbon, and recovered water of good quality from urine vapor.

  13. Aerobic composting of distilled grain waste eluted from a Chinese spirit-making process: The effects of initial pH adjustment.

    PubMed

    Wang, Shi-Peng; Zhong, Xiao-Zhong; Wang, Ting-Ting; Sun, Zhao-Yong; Tang, Yue-Qin; Kida, Kenji

    2017-12-01

    Aerobic composting of distilled grain waste (DGW) at different initial pH values adjusted by CaO addition was investigated. Three pH-adjusted treatments with initial pH values of 4 (R1), 5 (R2) and 6 (R3) and a control treatment (R0) with a pH value of 3.5 were conducted simultaneously. The results showed that R0 had an unsuccessful start-up of composting. However, the pH-adjusted treatments produced remarkable results, with a relatively high initial pH being beneficial for the start-up. Within 65days of composting, the degradation of volatile solids (VS) and the physicochemical properties of R2 and R3 displayed similar tendencies, and both produced a mature end-product, while R1 exhibited a lower VS degradation rate, and some of its physicochemical properties indicated the end-product was immature. Quantitative PCR analysis of ammonia oxidizers indicated that the occurrence of nitrification during the composting of DGW could be attributed to the activity of ammonia-oxidizing bacteria. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Metallic Sn spheres and SnO2@C core-shells by anaerobic and aerobic catalytic ethanol and CO oxidation reactions over SnO2 nanoparticles

    PubMed Central

    Kim, Won Joo; Lee, Sung Woo; Sohn, Youngku

    2015-01-01

    SnO2 has been studied intensely for applications to sensors, Li-ion batteries and solar cells. Despite this, comparatively little attention has been paid to the changes in morphology and crystal phase that occur on the metal oxide surface during chemical reactions. This paper reports anaerobic and aerobic ethanol and CO oxidation reactions over SnO2 nanoparticles (NPs), as well as the subsequent changes in the nature of the NPs. Uniform SnO2@C core-shells (10 nm) were formed by an aerobic ethanol oxidation reaction over SnO2 NPs. On the other hand, metallic Sn spheres were produced by an anaerobic ethanol oxidation reaction at 450 °C, which is significantly lower than that (1200 °C) used in industrial Sn production. Anaerobic and aerobic CO oxidation reactions were also examined. The novelty of the methods for the production of metallic Sn and SnO2@C core-shells including other anaerobic and aerobic reactions will contribute significantly to Sn and SnO2-based applications. PMID:26300041

  15. Climatic thresholds for pedogenic iron oxides under aerobic conditions: Processes and their significance in paleoclimate reconstruction

    NASA Astrophysics Data System (ADS)

    Long, Xiaoyong; Ji, Junfeng; Barrón, Vidal; Torrent, José

    2016-10-01

    Iron oxides are widely distributed across the surface of the Earth as a result of the aerobic weathering of primary Fe-bearing minerals. Pedogenic iron oxides which consist mainly of hematite (Hm), goethite (Gt), maghemite (Mgh), are often concentrated synchronously in aerobic soils under low to moderate rainfall regimes. Magnetic susceptibility (χ) and redness, which respectively reflect the content of Mgh and Hm in soils, are considered reasonable pedogenic and climatic indicators in soil taxonomy and paleorainfall reconstruction. However, under high rainfall regimes, the grain growth of Mgh and transformation to Hm, combined with the prior formation of Gt under conditions of high relative humidity (RH), can result in magnetic reduction and dramatic yellowing of soils and sediments, which explains the existence of rainfall thresholds for Mgh and Hm at a large scale even before the pedogenic environment turns anaerobic. In order to capture the rainfall thresholds for Mgh and Hm occurring under aerobic conditions, we explored a tropical transect across a granitic region where the soil color turned from red to yellow under a wide rainfall range of 900-2200 mm/yr and a corresponding mean annual RH range of 77%-85%. We observed a lower rainfall threshold of ∼1500 mm/yr and a corresponding RH ∼80% for Mgh and Hm along this transect, as well as a higher rainfall threshold of ∼1700 mm/yr and a corresponding RH of ∼81% for Gt and total pedogenic iron oxides (citrate/bicarbonate/dithionite-extractable Fe, Fed). Cross-referencing with comparable studies in temperate and subtropical regions, we noted that the rainfall or RH thresholds for Fed and Hm or Mgh likewise increase with temperature. Moreover, the different thresholds for total and individual iron oxide phase indicates that a negative correlation between chemical weathering intensity and redness or χ in sediment sequences can occur under the prevalent climate regime just between their thresholds. Finally

  16. Repeated application of composted tannery sludge affects differently soil microbial biomass, enzymes activity, and ammonia-oxidizing organisms.

    PubMed

    Araújo, Ademir Sérgio Ferreira; Lima, Luciano Moura; Santos, Vilma Maria; Schmidt, Radomir

    2016-10-01

    Repeated application of composted tannery sludge (CTS) changes the soil chemical properties and, consequently, can affect the soil microbial properties. The aim of this study was to evaluate the responses of soil microbial biomass and ammonia-oxidizing organisms to repeated application of CTS. CTS was applied repeatedly during 6 years, and, at the sixth year, the soil microbial biomass, enzymes activity, and ammonia-oxidizing organisms were determined in the soil. The treatments consisted of 0 (without CTS application), 2.5, 5, 10, and 20 t ha(-1) of CTS (dry basis). Soil pH, EC, SOC, total N, and Cr concentration increased with the increase in CTS rate. Soil microbial biomass did not change significantly with the amendment of 2.5 Mg ha(-1), while it decreased at the higher rates. Total and specific enzymes activity responded differently after CTS application. The abundance of bacteria did not change with the 2.5-Mg ha(-1) CTS treatment and decreased after this rate, while the abundance of archaea increased significantly with the 2.5-Mg ha(-1) CTS treatment. Repeated application of different CTS rates for 6 years had different effects on the soil microbial biomass and ammonia-oxidizing organisms as a response to changes in soil chemical properties.

  17. [Screening and ammoxidation characteristics of an ammonium oxidizing bacteria group].

    PubMed

    Yang, Xiaolong; Liu, Lihua; Wu, Bingqi; Liu, Shujie; Chen, Fuming

    2015-12-04

    This study aimed to screen high-performance ammonia oxidizing bacteria ( AOB) resistant to a high concentration of ammonia-nitrogen and low C/N ratio, for the development of novel AOB agents. Multi-point sampling, compulsory domestication, gradient dilution of domestication liquid were conducted to screen AOB with efficient and stable ammonia-nitrogen removing ability, and effects of different factors on its ammoxidation ability including C/N ratio, shaking speed and ammonia-nitrogen concentration were studied. Dominant strains were screened and identified by morphological observation, physiological and biochemical properties test and 16S rRNA sequence analysis. Three efficient AOB were obtained, among them a micro-flora named JQ8 showed the highest activity. The ammonia-nitrogen removal rate reached 95. 07% in a simulated wastewater with 17. 86 mmol/L of initial ammonia-nitrogen at C/N 4 treated by JQ8 for 6 days. Moreover, its ammonia nitrogen removal rate kept above 95% and net nitrogen removing rate nearly 80% in the solution with a C/N ratio above 4 and an NH₄⁺-N concentration below 28.57 mmol/L. The circuit board industry wastewater was treated using the laboratory-simulated aerobic active sludge disposal system. The removal rate of NH₄⁺-N and total nitrogen reached 87.8% and 67.6% respectively after 7 days' treatment using JQ8. Defluvibacter sp., Paracoccus sp. and Aquamicrobium sp. were identified as the dominant strains after the composition analysis of JQ8. An ammonia oxidizing bacteria consortium JQ8 screened from the landfill leachate showed a strong ammonium-nitrogen removal and endurance ability under low C/N ratio and high ammonia-nitrogen concentration, thus is probably applicable to intensify the ammonia-nitrogen removal treatment of industrial wastewater with sewage disposal system.

  18. Practical Aerobic Oxidations of Alcohols and Amines with Homogeneous Cu/TEMPO and Related Catalyst Systems

    PubMed Central

    Ryland, Bradford L.; Stahl, Shannon S.

    2014-01-01

    Alcohol and amine oxidations are common reactions in laboratory and industrial synthesis of organic molecules. Aerobic oxidation methods have long been sought for these transformations, but few practical methods exist that offer advantages over traditional oxidation methods. Recently developed homogeneous Cu/TEMPO (TEMPO = 2,2,6,6-tetramethylpiperidinyl-N-oxyl) and related catalyst systems appear to fill this void. The reactions exhibit high levels of chemoselectivity and broad functional-group tolerance, and they often operate efficiently at room temperature with ambient air as the oxidant. These advances, together with their historical context and recent applications, are highlighted in this minireview. PMID:25044821

  19. A new aerobic chemolithoautotrophic arsenic oxidizing microorganism isolated from a high Andean watershed.

    PubMed

    Anguita, Javiera M; Rojas, Claudia; Pastén, Pablo A; Vargas, Ignacio T

    2018-02-01

    Biological arsenic oxidation has been suggested as a key biogeochemical process that controls the mobilization and fate of this metalloid in aqueous environments. To the best of our knowledge, only four aerobic chemolithoautotrophic arsenite-oxidizing (CAO) bacteria have been shown to grow via direct arsenic oxidation and to have the essential genes for chemolithoautotrophic arsenite oxidation. In this study, a new CAO bacterium was isolated from a high Andean watershed evidencing natural dissolved arsenic attenuation. The bacterial isolate, designated TS-1, is closely related to the Ancylobacter genus, in the Alphaproteobacteria class. Results showed that TS-1 has genes for arsenite oxidation and carbon fixation. The dependence of bacterial growth from arsenite oxidation was demonstrated. In addition, a mathematical model was suggested and the kinetic parameters were obtained by simultaneously fitting the biomass growth, arsenite depletion curves, and arsenate production. This research increases the knowledge of chemolithoautotrophic arsenic oxidizing microorganisms and its potential role as a driver for natural arsenic attenuation.

  20. Aerobic oxidation in nanomicelles of aryl alkynes, in water at room temperature.

    PubMed

    Handa, Sachin; Fennewald, James C; Lipshutz, Bruce H

    2014-03-24

    On the basis of the far higher solubility of oxygen gas inside the hydrocarbon core of nanomicelles, metal and peroxide free aerobic oxidation of aryl alkynes to β-ketosulfones has been achieved in water at room temperature. Many examples are offered that illustrate broad functional group tolerance. The overall process is environmentally friendly, documented by the associated low E Factors. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Treatment of synthetic refinery wastewater in anoxic-aerobic sequential moving bed reactors and sulphur recovery.

    PubMed

    Mallick, Subrat Kumar; Chakraborty, Saswati

    2017-11-10

    Objective of the present study was to simultaneously biodegrade synthetic petroleum refinery wastewater containing phenol (750 mg/L), sulphide (750 mg/L), hydrocarbon (as emulsified diesel of 300 mg/L), ammonia-nitrogen (350 mg/L) at pH >9 in anoxic-aerobic sequential moving bed reactors. The optimum mixing speed of anoxic reactor was observed at 20 rpm and beyond that, removal rate remained constant. In anoxic reactor the minimum hydraulic retention time was observed to be 2 days for complete removal of sulphide, 40-50% removal of phenol and total hydrocarbons and 52% of sulphur recovery. The optimum HRT of aerobic moving bed reactor was observed as 16 h (total HRT of 64 h for anoxic and aerobic reactors) for complete removals of phenol, total hydrocarbons, COD (chemical oxygen demand) and ammonia-nitrogen with nitrification.

  2. Extensive nitrification and active ammonia oxidizers in two contrasting coastal systems of the Baltic Sea.

    PubMed

    Happel, Elisabeth; Bartl, Ines; Voss, Maren; Riemann, Lasse

    2018-06-19

    Nitrification is important in nitrogen (N) cycling of aquatic environments, but knowledge about its regulation and importance is sparse. Here we examined nitrification and ammonia oxidizers in the Baltic Sea. We investigated two sites with different catchment characteristics (agricultural and forest), the Bay of Gdánsk (south) and the Öre Estuary (north), and measured pelagic nitrification rates and abundance, composition, and expression of ammonia monooxygenase (amoA) genes. Highest nitrification rates were found in the nutrient rich Bay of Gdańsk. Interestingly, abundances of ammonia-oxidizing archaea (AOA) and bacteria (AOB) were orders of magnitude lower than reported from other sites. Although AOA were most abundant at both sites, the highest expression levels were from AOB. Interestingly, few AOA and AOB taxa dominated amoA gene expression, with a Nitrosomarinus related phylotype showing widespread expression. AOA and AOB communities differed between sites and depths, respectively, with the composition in rivers being distinct. A storm event, causing an even depth distribution of nitrification and particles in the Bay of Gdańsk, indicated that the presence of particles stimulate nitrification. The study highlights coastal regions as dynamic sites of extensive pelagic nitrification, which may affect local food web dynamics and loss of N mediated by denitrification. This article is protected by copyright. All rights reserved. © 2018 Society for Applied Microbiology and John Wiley & Sons Ltd.

  3. Dynamics of ultrathin V-oxide layers on Rh(111) in catalytic oxidation of ammonia and CO.

    PubMed

    von Boehn, B; Preiss, A; Imbihl, R

    2016-07-20

    Catalytic oxidation of ammonia and CO has been studied in the 10(-4) mbar range using a catalyst prepared by depositing ultra-thin vanadium oxide layers on Rh(111) (θV ≈ 0.2 MLE). Using photoemission electron microscopy (PEEM) as a spatially resolving method, we observe that upon heating in an atmosphere of NH3 and O2 the spatial homogeneity of the VOx layer is removed at 800 K and a pattern consisting of macroscopic stripes develops; at elevated temperatures this pattern transforms into a pattern of circular VOx islands. Under reaction conditions the neighboring VOx islands become attracted by each other and coalesce. Similar processes of pattern formation and island coalescence are observed in catalytic CO oxidation. Reoxidation of the reduced VOx catalyst proceeds via surface diffusion of oxygen adsorbed onto Rh(111). A pattern consisting of macroscopic circular VOx islands can also be obtained by heating a Rh(111)/VOx catalyst in pure O2.

  4. Synthesis of Formate Esters and Formamides Using an Au/TiO2-Catalyzed Aerobic Oxidative Coupling of Paraformaldehyde

    PubMed Central

    Metaxas, Ioannis; Vasilikogiannaki, Eleni

    2017-01-01

    A simple method for the synthesis of formate esters and formamides is presented based on the Au/TiO2-catalyzed aerobic oxidative coupling between alcohols or amines and formaldehyde. The suitable form of formaldehyde is paraformaldehyde, as cyclic trimeric 1,3,5-trioxane is inactive. The reaction proceeds via the formation of an intermediate hemiacetal or hemiaminal, respectively, followed by the Au nanoparticle-catalyzed aerobic oxidation of the intermediate. Typically, the oxidative coupling between formaldehyde (2 equiv) and amines occurs quantitatively at room temperature within 4 h, and there is no need to add a base as in analogous coupling reactions. The oxidative coupling between formaldehyde (typically 3 equiv) and alcohols is unprecedented and occurs more slowly, yet in good to excellent yields and selectivity. Minor side-products (2–12%) from the acetalization of formaldehyde by the alcohol are also formed. The catalyst is recyclable and can be reused after a simple filtration in five consecutive runs with a small loss of activity. PMID:29231853

  5. Evidence of novel plant-species specific ammonia oxidizing bacterial clades in acidic South African fynbos soils.

    PubMed

    Ramond, Jean-Baptiste; Lako, Joseph D W; Stafford, William H L; Tuffin, Marla I; Cowan, Don A

    2015-08-01

    Ammonia-oxidizing bacteria (AOB) are essential in the biogeochemical cycling of nitrogen as they catalyze the rate-limiting oxidation of ammonia into nitrite. Since their first isolation in the late 19th century, chemolithoautotrophic AOBs have been identified in a wide range of natural (e.g., soils, sediments, estuarine, and freshwaters) and man created or impacted habitats (e.g., wastewater treatment plants and agricultural soils). However, little is known on the plant-species association of AOBs, particularly in the nutrient-starved fynbos terrestrial biome. In this study, we evaluated the diversity of AOBs in the plant canopy of three South African fynbos-specific plant species, namely Leucadendron xanthoconus, Leucospermum truncatulum and Leucadendron microcephalum, through the construction of amoA-gene clone libraries. Our results clearly demonstrate that plant-species specific and monophyletic AOB clades are present in fynbos canopy soils. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Polyaniline-based optical ammonia detector

    DOEpatents

    Duan, Yixiang; Jin, Zhe; Su, Yongxuan

    2002-01-01

    Electronic absorption spectroscopy of a polyaniline film deposited on a polyethylene surface by chemical oxidation of aniline monomer at room temperature was used to quantitatively detect ammonia gas. The present optical ammonia gas detector was found to have a response time of less than 15 s, a regeneration time of less than 2 min. at room temperature, and a detection limit of 1 ppm (v/v) for ammonia, with a linear dynamic range from 180 ppm to 18,000 ppm.

  7. Cyanate as energy source for nitrifiers

    PubMed Central

    Palatinszky, Marton; Herbold, Craig; Jehmlich, Nico; Pogoda, Mario; Han, Ping; von Bergen, Martin; Lagkouvardos, Ilias; Karst, Søren M.; Galushko, Alexander; Koch, Hanna; Berry, David; Daims, Holger; Wagner, Michael

    2015-01-01

    Ammonia- and nitrite-oxidizers are collectively responsible for the aerobic oxidation of ammonia via nitrite to nitrate and play essential roles for the global biogeochemical nitrogen cycle. The physiology of these nitrifying microbes has been intensively studied since the first experiments of Sergei Winogradsky more than a century ago. Urea and ammonia are the only recognized energy sources that promote the aerobic growth of ammonia-oxidizing bacteria and archaea. Here we report the aerobic growth of a pure culture of the ammonia-oxidizing thaumarchaeote Nitrososphaera gargensis1 on cyanate as the sole source of energy and reductant, the first organism known to do so. Cyanate, which is a potentially important source of reduced nitrogen in aquatic and terrestrial ecosystems2, is converted to ammonium and CO2 by this archaeon using a cyanase that is induced upon addition of this compound. Within the cyanase gene family, this cyanase is a member of a distinct clade that also contains cyanases of nitrite-oxidizing bacteria of the genus Nitrospira. We demonstrate by co-culture experiments that these nitrite-oxidizers supply ammonia-oxidizers lacking cyanase with ammonium from cyanate, which is fully nitrified by this consortium through reciprocal feeding. Screening of a comprehensive set of more than 3,000 publically available metagenomes from environmental samples revealed that cyanase-encoding genes clustering with the cyanases of these nitrifiers are widespread in the environment. Our results demonstrate an unexpected metabolic versatility of nitrifying microbes and suggest a previously unrecognized importance of cyanate for N-cycling in the environment. PMID:26222031

  8. Global ecological pattern of ammonia-oxidizing archaea.

    PubMed

    Cao, Huiluo; Auguet, Jean-Christophe; Gu, Ji-Dong

    2013-01-01

    The global distribution of ammonia-oxidizing archaea (AOA), which play a pivotal role in the nitrification process, has been confirmed through numerous ecological studies. Though newly available amoA (ammonia monooxygenase subunit A) gene sequences from new environments are accumulating rapidly in public repositories, a lack of information on the ecological and evolutionary factors shaping community assembly of AOA on the global scale is apparent. We conducted a meta-analysis on uncultured AOA using over ca. 6,200 archaeal amoA gene sequences, so as to reveal their community distribution patterns along a wide spectrum of physicochemical conditions and habitat types. The sequences were dereplicated at 95% identity level resulting in a dataset containing 1,476 archaeal amoA gene sequences from eight habitat types: namely soil, freshwater, freshwater sediment, estuarine sediment, marine water, marine sediment, geothermal system, and symbiosis. The updated comprehensive amoA phylogeny was composed of three major monophyletic clusters (i.e. Nitrosopumilus, Nitrosotalea, Nitrosocaldus) and a non-monophyletic cluster constituted mostly by soil and sediment sequences that we named Nitrososphaera. Diversity measurements indicated that marine and estuarine sediments as well as symbionts might be the largest reservoirs of AOA diversity. Phylogenetic analyses were further carried out using macroevolutionary analyses to explore the diversification pattern and rates of nitrifying archaea. In contrast to other habitats that displayed constant diversification rates, marine planktonic AOA interestingly exhibit a very recent and accelerating diversification rate congruent with the lowest phylogenetic diversity observed in their habitats. This result suggested the existence of AOA communities with different evolutionary history in the different habitats. Based on an up-to-date amoA phylogeny, this analysis provided insights into the possible evolutionary mechanisms and environmental

  9. Effects of combined application of nitrogen fertilizer and biochar on the nitrification and ammonia oxidizers in an intensive vegetable soil.

    PubMed

    Bi, Qing-Fang; Chen, Qiu-Hui; Yang, Xiao-Ru; Li, Hu; Zheng, Bang-Xiao; Zhou, Wei-Wei; Liu, Xiao-Xia; Dai, Pei-Bin; Li, Ke-Jie; Lin, Xian-Yong

    2017-11-07

    Soil amended with single biochar or nitrogen (N) fertilizer has frequently been reported to alter soil nitrification process due to its impact on soil properties. However, little is known about the dynamic response of nitrification and ammonia-oxidizers to the combined application of biochar and N fertilizer in intensive vegetable soil. In this study, an incubation experiment was designed to evaluate the effects of biochar and N fertilizer application on soil nitrification, abundance and community shifts of ammonia-oxidizing bacteria (AOB) and ammonia oxidizing archaea (AOA) in Hangzhou greenhouse vegetable soil. Results showed that single application of biochar had no significant effect on soil net nitrification rates and ammonia-oxidizers. Conversely, the application of only N fertilizer and N fertilizer + biochar significantly increased net nitrification rate and the abundance of AOB rather than AOA, and only AOB abundance was significantly correlated with soil net nitrification rate. Moreover, the combined application of N fertilizer and biochar had greater effect on AOB communities than that of the only N fertilizers, and the relative abundance of 156 bp T-RF (Nitrosospira cluster 3c) decreased but 60 bp T-RF (Nitrosospira cluster 3a and cluster 0) increased to become a single predominant group. Phylogenetic analysis indicated that all the AOB sequences were grouped into Nitrosospira cluster, and most of AOA sequences were clustered within group 1.1b. We concluded that soil nitrification was stimulated by the combined application of N fertilizer and biochar via enhancing the abundance and shifting the community composition of AOB rather than AOA in intensive vegetable soil.

  10. Influence of edaphic and management factors on the diversity and abundance of ammonia-oxidizing thaumarchaeota and bacteria in soils of bioenergy crop cultivars.

    PubMed

    Bertagnolli, Anthony D; Meinhardt, Kelley A; Pannu, Manmeet; Brown, Sally; Strand, Stuart; Fransen, Steven C; Stahl, David A

    2015-04-01

    Ammonia-oxidizing thaumarcheota (AOA) and ammonia-oxidizing bacteria (AOB) differentially influence soil and atmospheric chemistry, but soil properties that control their distributions are poorly understood. In this study, the ammonia monooxygenase gene (amoA) was used to identify and quantify presumptive AOA and AOB and relate their distributions to soil properties in two experimental fields planted with different varieties of switchgrass (Panicum virgatum), a potential bioenergy feedstock. Differences in ammonia oxidizer diversity were associated primarily with soil properties of the two field sites, with pH displaying significant correlations with both AOA and AOB population structure. Percent nitrogen (%N), carbon to nitrogen ratios (C : N), and pH were also correlated with shifts nitrifier population structure. Nitrosotalea-like and Nitrosospira cluster II populations were more highly represented in acidic soils, whereas populations affiliated with Nitrososphaera and Nitrosospira cluster 3A.1 were relatively more abundant in alkaline soils. AOA were the dominant functional group in all plots based on quantitative polymerase chain reaction and high-throughput sequencing analyses. These data suggest that AOA contribute significantly to nitrification rates in carbon and nitrogen rich soils influenced by perennial grasses. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.

  11. Genome-Scale, Constraint-Based Modeling of Nitrogen Oxide Fluxes during Coculture of Nitrosomonas europaea and Nitrobacter winogradskyi

    PubMed Central

    Giguere, Andrew T.; Murthy, Ganti S.; Bottomley, Peter J.; Sayavedra-Soto, Luis A.

    2018-01-01

    ABSTRACT Nitrification, the aerobic oxidation of ammonia to nitrate via nitrite, emits nitrogen (N) oxide gases (NO, NO2, and N2O), which are potentially hazardous compounds that contribute to global warming. To better understand the dynamics of nitrification-derived N oxide production, we conducted culturing experiments and used an integrative genome-scale, constraint-based approach to model N oxide gas sources and sinks during complete nitrification in an aerobic coculture of two model nitrifying bacteria, the ammonia-oxidizing bacterium Nitrosomonas europaea and the nitrite-oxidizing bacterium Nitrobacter winogradskyi. The model includes biotic genome-scale metabolic models (iFC578 and iFC579) for each nitrifier and abiotic N oxide reactions. Modeling suggested both biotic and abiotic reactions are important sources and sinks of N oxides, particularly under microaerobic conditions predicted to occur in coculture. In particular, integrative modeling suggested that previous models might have underestimated gross NO production during nitrification due to not taking into account its rapid oxidation in both aqueous and gas phases. The integrative model may be found at https://github.com/chaplenf/microBiome-v2.1. IMPORTANCE Modern agriculture is sustained by application of inorganic nitrogen (N) fertilizer in the form of ammonium (NH4+). Up to 60% of NH4+-based fertilizer can be lost through leaching of nitrifier-derived nitrate (NO3−), and through the emission of N oxide gases (i.e., nitric oxide [NO], N dioxide [NO2], and nitrous oxide [N2O] gases), the latter being a potent greenhouse gas. Our approach to modeling of nitrification suggests that both biotic and abiotic mechanisms function as important sources and sinks of N oxides during microaerobic conditions and that previous models might have underestimated gross NO production during nitrification. PMID:29577088

  12. Genome-Scale, Constraint-Based Modeling of Nitrogen Oxide Fluxes during Coculture of Nitrosomonas europaea and Nitrobacter winogradskyi.

    PubMed

    Mellbye, Brett L; Giguere, Andrew T; Murthy, Ganti S; Bottomley, Peter J; Sayavedra-Soto, Luis A; Chaplen, Frank W R

    2018-01-01

    Nitrification, the aerobic oxidation of ammonia to nitrate via nitrite, emits nitrogen (N) oxide gases (NO, NO 2 , and N 2 O), which are potentially hazardous compounds that contribute to global warming. To better understand the dynamics of nitrification-derived N oxide production, we conducted culturing experiments and used an integrative genome-scale, constraint-based approach to model N oxide gas sources and sinks during complete nitrification in an aerobic coculture of two model nitrifying bacteria, the ammonia-oxidizing bacterium Nitrosomonas europaea and the nitrite-oxidizing bacterium Nitrobacter winogradskyi . The model includes biotic genome-scale metabolic models (iFC578 and iFC579) for each nitrifier and abiotic N oxide reactions. Modeling suggested both biotic and abiotic reactions are important sources and sinks of N oxides, particularly under microaerobic conditions predicted to occur in coculture. In particular, integrative modeling suggested that previous models might have underestimated gross NO production during nitrification due to not taking into account its rapid oxidation in both aqueous and gas phases. The integrative model may be found at https://github.com/chaplenf/microBiome-v2.1. IMPORTANCE Modern agriculture is sustained by application of inorganic nitrogen (N) fertilizer in the form of ammonium (NH 4 + ). Up to 60% of NH 4 + -based fertilizer can be lost through leaching of nitrifier-derived nitrate (NO 3 - ), and through the emission of N oxide gases (i.e., nitric oxide [NO], N dioxide [NO 2 ], and nitrous oxide [N 2 O] gases), the latter being a potent greenhouse gas. Our approach to modeling of nitrification suggests that both biotic and abiotic mechanisms function as important sources and sinks of N oxides during microaerobic conditions and that previous models might have underestimated gross NO production during nitrification.

  13. Ammonia-oxidizing bacteria and archaea in wastewater treatment plant sludge and nearby coastal sediment in an industrial area in China.

    PubMed

    Zhang, Yan; Chen, Lujun; Sun, Renhua; Dai, Tianjiao; Tian, Jinping; Wen, Donghui

    2015-05-01

    Under the increasing pressure of human activities, Hangzhou Bay has become one of the most seriously polluted waters along China's coast. Considering the excessive inorganic nitrogen detected in the bay, in this study, the impact of an effluent from a coastal industrial park on ammonia-oxidizing microorganisms (AOMs) of the receiving area was interpreted for the first time by molecular technologies. Revealed by real-time PCR, the ratio of archaeal amoA/bacterial amoA ranged from 5.68 × 10(-6) to 4.79 × 10(-5) in the activated sludge from two wastewater treatment plants (WWTPs) and 0.54-3.44 in the sediments from the effluent receiving coastal area. Analyzed by clone and pyrosequencing libraries, genus Nitrosomonas was the predominant ammonia-oxidizing bacteria (AOB), but no ammonia-oxidizing archaea (AOA) was abundant enough for sequencing in the activated sludge from the WWTPs; genus Nitrosomonas and Nitrosopumilus were the dominant AOB and AOA, respectively, in the coastal sediments. The different abundance of AOA but similar structure of AOB between the WWTPs and nearby coastal area probably indicated an anthropogenic impact on the microbial ecology in Hangzhou Bay.

  14. Removal of triclosan in nitrifying activated sludge: effects of ammonia amendment and bioaugmentation.

    PubMed

    Lee, Do Gyun; Cho, Kun-Ching; Chu, Kung-Hui

    2015-04-01

    This study investigated two possible strategies, increasing ammonia oxidation activity and bioaugmenting with triclosan-degrader Sphingopyxis strain KCY1, to enhance triclosan removal in nitrifying activated sludge (NAS). Triclosan (2 mg L(-1)) was removed within 96-h in NAS bioreactors amended with 5, 25 and 75 mg L(-1) of ammonium (NH4-N). The fastest triclosan removal was observed in 25 mg NH4-NL(-1) amended-bioreactors where high ammonia oxidation occurred. Inhibition of ammonia oxidation and slower triclosan removal were observed in 75 mg NH4-NL(-1) amended-bioreactors. Triclosan removal was correlated to the molar ratio of the amount of nitrate produced to the amount of ammonium removed. Bioaugmentation with strain KCY1 did not enhance triclosan removal in the bioreactors with active ammonia oxidation. Approximately 36-42% and 59% of triclosan added were removed within 24-h by ammonia-oxidizing bacteria and unknown triclosan-degrading heterotrophs, respectively. The results suggested that increasing ammonia oxidation activity can be an effective strategy to enhance triclosan removal in NAS. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Nitrification rates in Arctic soils are associated with functionally distinct populations of ammonia-oxidizing archaea

    PubMed Central

    Alves, Ricardo J Eloy; Wanek, Wolfgang; Zappe, Anna; Richter, Andreas; Svenning, Mette M; Schleper, Christa; Urich, Tim

    2013-01-01

    The functioning of Arctic soil ecosystems is crucially important for global climate, and basic knowledge regarding their biogeochemical processes is lacking. Nitrogen (N) is the major limiting nutrient in these environments, and its availability is strongly dependent on nitrification. However, microbial communities driving this process remain largely uncharacterized in Arctic soils, namely those catalyzing the rate-limiting step of ammonia (NH3) oxidation. Eleven Arctic soils were analyzed through a polyphasic approach, integrating determination of gross nitrification rates, qualitative and quantitative marker gene analyses of ammonia-oxidizing archaea (AOA) and bacteria (AOB) and enrichment of AOA in laboratory cultures. AOA were the only NH3 oxidizers detected in five out of 11 soils and outnumbered AOB in four of the remaining six soils. The AOA identified showed great phylogenetic diversity and a multifactorial association with the soil properties, reflecting an overall distribution associated with tundra type and with several physico-chemical parameters combined. Remarkably, the different gross nitrification rates between soils were associated with five distinct AOA clades, representing the great majority of known AOA diversity in soils, which suggests differences in their nitrifying potential. This was supported by selective enrichment of two of these clades in cultures with different NH3 oxidation rates. In addition, the enrichments provided the first direct evidence for NH3 oxidation by an AOA from an uncharacterized Thaumarchaeota–AOA lineage. Our results indicate that AOA are functionally heterogeneous and that the selection of distinct AOA populations by the environment can be a determinant for nitrification activity and N availability in soils. PMID:23466705

  16. Ammonia oxidizer populations vary with nitrogen cycling across a tropical montane mean annual temperature gradient

    Treesearch

    S. Pierre; I. Hewson; J. P. Sparks; C. M. Litton; C. Giardina; P. M. Groffman; T. J. Fahey

    2017-01-01

    Functional gene approaches have been used to better understand the roles of microbes in driving forest soil nitrogen (N) cycling rates and bioavailability. Ammonia oxidation is a rate limiting step in nitrification, and is a key area for understanding environmental constraints on N availability in forests. We studied how increasing temperature affects the role of...

  17. Ammonia oxidation-dependent growth of group I.1b Thaumarchaeota in acidic red soil microcosms.

    PubMed

    Wu, Yucheng; Conrad, Ralf

    2014-07-01

    Accumulating evidence suggests that Thaumarchaeota may control nitrification in acidic soils. However, the composition of the thaumarchaeotal communities and their functioning is not well known. Therefore, we studied nitrification activity in relation to abundance and composition of Thaumarchaeota in an acidic red soil from China, using microcosms incubated with and without cellulose amendment. Cellulose was selected to simulate the input of crop residues used to increase soil fertility by local farming. Accumulation of NO3-(-N) was correlated with the growth of Thaumarchaeota as determined by qPCR of 16S rRNA and ammonia monooxygenase (amoA) genes. Both nitrification activity and thaumarchaeotal growth were inhibited by acetylene. They were also inhibited by cellulose amendment, possibly due to the depletion of ammonium by enhanced heterotrophic assimilation. These results indicated that growth of Thaumarchaeota was dependent on ammonia oxidation. The thaumarchaeotal 16S rRNA gene sequences in the red soil were dominated by a clade related to soil fosmid clone 29i4 within the group I.1b, which is widely distributed but so far uncultured. The archaeal amoA sequences were mainly related to the Nitrososphaera sister cluster. These observations suggest that fosmid clone 29i4 and Nitrososphaera sister cluster represent the same group of Thaumarchaeota and dominate ammonia oxidation in acidic red soil. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  18. High Ph, Ammonia Toxicity, and the Search for Life on the Jovian Planets

    NASA Technical Reports Server (NTRS)

    Deal, P. H.; Souza, K. A.; Mack, H. M.

    1975-01-01

    The effects of pH and ammonia concentration were studied separately, where possible, on a variety of organisms, including some isolated from natural environments of high pH and/or ammonia concentration. Escherichia coli and Bacillus subtilis are both extremely sensitive to ammonia. An aerobic organism (growth up to pH 11.4) from an alkaline spring is more resistant, but exhibits a toxic response to ammonia at a pH much lower than its maximum for growth. The greatest ammonia resistance has been found in an unidentified organism growing at near neutral pH. Even in this case, however, urvival at ammonia concentrations reasonably expected on the Jovian planets is measured in hours. This is two to three orders of magnitude longer than for E. coli. Results support the tentative conclusion that contamination of the Jovian planets with terrestrial organisms that can grow is unlikely. However, the range of toxic response noted, coupled with the observation that terrestrial life has not been exposed to high ammonia concentrations for millions of years, suggests that adaptation to greater ammonia tolerance may be possible.

  19. Electrocatalytic effect of polyvinyl pyrrolidone capped platinum nanoparticles electrodeposited on platinum electrode for ammonia oxidation

    NASA Astrophysics Data System (ADS)

    Mayedwa, Noluthando; Matinise, Nolubabalo; Mongwaketsi, Nametso; Maaza, Malik

    2018-05-01

    The aim of this work was to study structural and kinetic parameters as well as the mechanism of platinum nanoparticles (PtNP) reduced with sodium borohydride (NaBH4) and capped with polyvinyl pyrrolidone (PVP). The nanoparticles were supported on Pt electrode for ammonia oxidation in fuel cell application. X-ray diffraction (XRD) was used to study structural composition and high resolution transmission electron microscopy (HRTEM) was used for morphological study of the nanoalloy. The electrocatalysts were studied in alkaline solution of potassium hydroxide (KOH) by cyclic voltammetry (CV), square wave voltammetry (SWV) and electrochemical impedance spectroscopy (EIS). CV showed that the ammonia oxidation over potential for PtNP was -431 mV and with exchange current density of 1.726 × 10-4 A. EIS showed that the charge transfer resistance (Rct) of PtNP was the lowest (Rct = 1.943 × 106 Ω) compared to that of bare Pt working electrode (2.0604 × 106 Ω), indicating that the Pt nanoparticles have good conductivity and played an important role in accelerating the transfer of electrons.

  20. Community size and composition of ammonia oxidizers and denitrifiers in an alluvial intertidal wetland ecosystem

    PubMed Central

    Hu, Ziye; Meng, Han; Shi, Jin-Huan; Bu, Nai-Shun; Fang, Chang-Ming; Quan, Zhe-Xue

    2014-01-01

    Global nitrogen cycling is mainly mediated by the activity of microorganisms. Nitrogen cycle processes are mediated by functional groups of microorganisms that are affected by constantly changing environmental conditions and substrate availability. In this study, we investigated the temporal and spatial patterns of nitrifier and denitrifier communities in an intertidal wetland. Soil samples were collected over four distinct seasons from three locations with different vegetative cover. Multiple environmental factors and process rates were measured and analyzed together with the community size and composition profiles. We observed that the community size and composition of the nitrifiers and denitrifiers are affected significantly by seasonal factors, while vegetative cover affected the community composition. The seasonal impacts on the community size of ammonia oxidizing archaea (AOA) are much higher than that of ammonia oxidizing bacteria (AOB). The seasonal change was a more important indicator for AOA community composition patterns, while vegetation was more important for the AOB community patterns. The microbial process rates were correlated with both the community size and composition. PMID:25101072

  1. Characterization of two ammonia-oxidizing bacteria isolated from reactors operated with low dissolved oxygen concentrations.

    PubMed

    Park, H-D; Noguera, D R

    2007-05-01

    To obtain ammonia-oxidizing bacterial (AOB) strains inhabiting low dissolved oxygen (DO) environments and to characterize them to better understand their function and ecology. Using a serial dilution method, two AOB strains (ML1 and NL7) were isolated from chemostat reactors operated with low DO concentrations (0.12-0.24 mg l(-1)). Phylogenetically, strains ML1 and NL7 are affiliated to AOB within the Nitrosomonas europaea and Nitrosomonas oligotropha lineages, respectively. Kinetically, strain ML1 had high affinity for oxygen (0.24 +/- 0.13 mg l(-1)) and low affinity for ammonia (1.62 +/- 0.97 mg N l(-1)), while strain NL7 had high affinity for ammonia (0.48 +/- 0.35 mg l(-1)), but a surprisingly low affinity for oxygen (1.22 +/- 0.43 mg l(-1)). A co-culture experiment was used to iteratively estimate decay constants for both strains. The results indicated that AOB without high affinity for oxygen may have other mechanisms to persist in low DO environments, with high affinity for ammonia being important. This study provides a method to determine AOB growth kinetic parameters without assuming or neglecting decay constant. And, this is the first report on oxygen affinity constant of a N. oligotropha strain.

  2. Highly efficient aerobic oxidation of alcohols by using less-hindered nitroxyl-radical/copper catalysis: optimum catalyst combinations and their substrate scope.

    PubMed

    Sasano, Yusuke; Kogure, Naoki; Nishiyama, Tomohiro; Nagasawa, Shota; Iwabuchi, Yoshiharu

    2015-04-01

    The oxidation of alcohols into their corresponding carbonyl compounds is one of the most fundamental transformations in organic chemistry. In our recent report, 2-azaadamantane N-oxyl (AZADO)/copper catalysis promoted the highly chemoselective aerobic oxidation of unprotected amino alcohols into amino carbonyl compounds. Herein, we investigated the extension of the promising AZADO/copper-catalyzed aerobic oxidation of alcohols to other types of alcohol. During close optimization of the reaction conditions by using various alcohols, we found that the optimum combination of nitroxyl radical, copper salt, and solution concentration was dependent on the type of substrate. Various alcohols, including highly hindered and heteroatom-rich ones, were efficiently oxidized into their corresponding carbonyl compounds under mild conditions with lower amounts of the catalysts. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Molecular characterization of a microbial consortium involved in methane oxidation coupled to denitrification under micro-aerobic conditions

    PubMed Central

    Liu, Jingjing; Sun, Faqian; Wang, Liang; Ju, Xi; Wu, Weixiang; Chen, Yingxu

    2014-01-01

    Methane can be used as an alternative carbon source in biological denitrification because it is nontoxic, widely available and relatively inexpensive. A microbial consortium involved in methane oxidation coupled to denitrification (MOD) was enriched with nitrite and nitrate as electron acceptors under micro-aerobic conditions. The 16S rRNA gene combined with pmoA phylogeny of methanotrophs and nirK phylogeny of denitrifiers were analysed to reveal the dominant microbial populations and functional microorganisms. Real-time quantitative polymerase chain reaction results showed high numbers of methanotrophs and denitrifiers in the enriched consortium. The 16S rRNA gene clone library revealed that Methylococcaceae and Methylophilaceae were the dominant populations in the MOD ecosystem. Phylogenetic analyses of pmoA gene clone libraries indicated that all methanotrophs belonged to Methylococcaceae, a type I methanotroph employing the ribulose monophosphate pathway for methane oxidation. Methylotrophic denitrifiers of the Methylophilaceae that can utilize organic intermediates (i.e. formaldehyde, citrate and acetate) released from the methanotrophs played a vital role in aerobic denitrification. This study is the first report to confirm micro-aerobic denitrification and to make phylogenetic and functional assignments for some members of the microbial assemblages involved in MOD. PMID:24245852

  4. Geographic and seasonal variation of dissolved methane and aerobic methane oxidation in Alaskan lakes

    DOE PAGES

    Martinez-Cruz, K.; Sepulveda-Jauregui, A.; Walter Anthony, K.; ...

    2015-08-04

    Methanotrophic bacteria play an important role oxidizing a significant fraction of methane (CH 4) produced in lakes. Aerobic CH 4 oxidation depends mainly on lake CH 4 and oxygen (O 2) concentrations, in such a manner that higher MO rates are usually found at the oxic/anoxic interface, where both molecules are present. MO also depends on temperature, and via methanogenesis, on organic carbon input to lakes, including from thawing permafrost in thermokarst (thaw)-affected lakes. Given the large variability in these environmental factors, CH 4 oxidation is expected to be subject to large seasonal and geographic variations, which have been scarcelymore » reported in the literature. In the present study, we measured CH 4 oxidation rates in 30 Alaskan lakes along a north-south latitudinal transect during winter and summer with a new field laser spectroscopy method. Additionally, we measured dissolved CH 4 and O 2 concentrations. Here, we found that in the winter, aerobic CH 4 oxidation was mainly controlled by the dissolved O 2 concentration, while in the summer it was controlled primarily by the CH 4 concentration, which was scarce compared to dissolved O 2. The permafrost environment of the lakes was identified as another key factor. Thermokarst (thaw) lakes formed in yedoma-type permafrost had significantly higher CH 4 oxidation rates compared to other thermokarst and non-thermokarst lakes formed in non-yedoma permafrost environments. As thermokarst lakes formed in yedoma-type permafrost have been identified to receive large quantities of terrestrial organic carbon from thaw and subsidence of the surrounding landscape into the lake, confirming the strong coupling between terrestrial and aquatic habitats and its influence on CH 4 cycling.« less

  5. Geographic and seasonal variation of dissolved methane and aerobic methane oxidation in Alaskan lakes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Martinez-Cruz, K.; Sepulveda-Jauregui, A.; Walter Anthony, K.

    Methanotrophic bacteria play an important role oxidizing a significant fraction of methane (CH 4) produced in lakes. Aerobic CH 4 oxidation depends mainly on lake CH 4 and oxygen (O 2) concentrations, in such a manner that higher MO rates are usually found at the oxic/anoxic interface, where both molecules are present. MO also depends on temperature, and via methanogenesis, on organic carbon input to lakes, including from thawing permafrost in thermokarst (thaw)-affected lakes. Given the large variability in these environmental factors, CH 4 oxidation is expected to be subject to large seasonal and geographic variations, which have been scarcelymore » reported in the literature. In the present study, we measured CH 4 oxidation rates in 30 Alaskan lakes along a north-south latitudinal transect during winter and summer with a new field laser spectroscopy method. Additionally, we measured dissolved CH 4 and O 2 concentrations. Here, we found that in the winter, aerobic CH 4 oxidation was mainly controlled by the dissolved O 2 concentration, while in the summer it was controlled primarily by the CH 4 concentration, which was scarce compared to dissolved O 2. The permafrost environment of the lakes was identified as another key factor. Thermokarst (thaw) lakes formed in yedoma-type permafrost had significantly higher CH 4 oxidation rates compared to other thermokarst and non-thermokarst lakes formed in non-yedoma permafrost environments. As thermokarst lakes formed in yedoma-type permafrost have been identified to receive large quantities of terrestrial organic carbon from thaw and subsidence of the surrounding landscape into the lake, confirming the strong coupling between terrestrial and aquatic habitats and its influence on CH 4 cycling.« less

  6. Abundance and diversity of ammonia-oxidizing archaea in response to various habitats in Pearl River Delta of China, a subtropical maritime zone.

    PubMed

    Li, Zhixin; Jin, Wenbiao; Liang, Zhaoyun; Yue, Yangyang; Lv, Junhong

    2013-06-01

    Ammonia-oxidizing archaea (AOA) are widely considered key to ammonia oxidation in various environments. However, little work has been conducted to simultaneously investigate the abundance and diversity of AOA as well as correlations between archaeal amoA genotypes and environmental parameters of different ecosystems at one district. To understand the abundance, diversity, and distribution of AOA in Pearl River Delta of China in response to various habitats, the archaeal amoA genes in soil, marine, river, lake, hot spring and wastewater treatment plant (WWTP) samples were investigated using real-time fluorescent quantitative PCR and clone libraries. Our analyses indicated that the diversity of AOA in various habitats was different and could be clustered into five major clades, i.e., estuary sediment, marine water/sediment, soil, hot spring and Cluster 1. Phylogenetic analyses revealed that the structure of AOA communities in similar ecological habitats exhibited strong relation. The canonical correspondence method indicated that the AOA community structure was strongly correlated to temperature, pH, total organic carbon, total nitrogen and dissolved oxygen variables. Assessing AOA amoA gene copy numbers, ranging from 6.84 x 10(6) to 9.45 x 10(7) copies/g in dry soil/sediment, and 6.06 x 10(6) to 2.41 x 10(7) copies/L in water samples, were higher than ammonia-oxidizing bacteria (AOB) by 1-2 orders of magnitude. However, AOA amoA copy numbers were much lower than AOB in WWTP activated sludge samples. Overall, these studies suggested that AOA may be a major contributor to ammonia oxidation in natural habitats but play a minor role in highly aerated activated sludge. The result also showed the ratio of AOA to AOB amoA gene abundance was positively correlated with temperature and less correlated with other environmental parameters. New data from our study provide increasing evidence for the relative abundance and diversity of ammonia-oxidizing archaea in the global

  7. Trp64Arg Polymorphism in Beta3-Adrenergic Receptor Gene Is Associated with Decreased Fat Oxidation Both in Resting and Aerobic Exercise in the Japanese Male

    PubMed Central

    Morita, Emiko; Taniguchi, Hiroshi; Sakaue, Motoyoshi

    2009-01-01

    The purpose of our study was to investigate whether the Trp64Arg polymorphism in β3-AR gene and the −3826A/G polymorphism in the UCP1 gene were associated with the reduction in energy expenditure and fat oxidation both in resting and aerobic exercise in Japanese. Eighty-six nonobese young healthy Japanese were recruited. Energy expenditure was measured using indirect calorimetry. The subjects performed an aerobic exercise program at 60% of their maximal heart rate for 30 minutes. The level of fat oxidation at rest and aerobic exercise of the male subjects with Trp/Arg of the β3-AR gene was significantly lower than that of the Trp/Trp genotype. No difference in FO0−30 was observed in the female subjects. There was no association between UCP-1 polymorphism and energy expenditure during aerobic exercise. It was revealed that the Trp64Arg polymorphism in β3-AR gene is associated with reduction of fat oxidation both in resting and aerobic exercise in healthy, young Japanese males. PMID:20069060

  8. Trp64Arg polymorphism in beta3-adrenergic receptor gene is associated with decreased fat oxidation both in resting and aerobic exercise in the Japanese male.

    PubMed

    Morita, Emiko; Taniguchi, Hiroshi; Sakaue, Motoyoshi

    2009-01-01

    The purpose of our study was to investigate whether the Trp64Arg polymorphism in beta3-AR gene and the -3826A/G polymorphism in the UCP1 gene were associated with the reduction in energy expenditure and fat oxidation both in resting and aerobic exercise in Japanese. Eighty-six nonobese young healthy Japanese were recruited. Energy expenditure was measured using indirect calorimetry. The subjects performed an aerobic exercise program at 60% of their maximal heart rate for 30 minutes. The level of fat oxidation at rest and aerobic exercise of the male subjects with Trp/Arg of the beta3-AR gene was significantly lower than that of the Trp/Trp genotype. No difference in FO(0-30) was observed in the female subjects. There was no association between UCP-1 polymorphism and energy expenditure during aerobic exercise. It was revealed that the Trp64Arg polymorphism in beta3-AR gene is associated with reduction of fat oxidation both in resting and aerobic exercise in healthy, young Japanese males.

  9. A Bioinspired Catalytic Aerobic Oxidative C–H Functionalization of Primary Aliphatic Amines: Synthesis of 1,2-Disubstituted Benzimidazoles

    PubMed Central

    Nguyen, Khac Minh Huy; Largeron, Martine

    2015-01-01

    Aerobic oxidative C–H functionalization of primary aliphatic amines has been accomplished with a biomimetic cooperative catalytic system to furnish 1,2-disubstituted benzimidazoles that play an important role as drug discovery targets. This one-pot atom-economical multistep process, which proceeds under mild conditions, with ambient air and equimolar amounts of each coupling partner, constitutes a convenient environmentally friendly strategy to functionalize non-activated aliphatic amines that remain challenging substrates for non-enzymatic catalytic aerobic systems. PMID:26206475

  10. Practical aerobic oxidations of alcohols and amines with homogeneous copper/TEMPO and related catalyst systems.

    PubMed

    Ryland, Bradford L; Stahl, Shannon S

    2014-08-18

    Oxidations of alcohols and amines are common reactions in the synthesis of organic molecules in the laboratory and industry. Aerobic oxidation methods have long been sought for these transformations, but few practical methods exist that offer advantages over traditional oxidation methods. Recently developed homogeneous Cu/TEMPO (TEMPO = 2,2,6,6-tetramethylpiperidinyl-N-oxyl) and related catalyst systems appear to fill this void. The reactions exhibit high levels of chemoselectivity and broad functional-group tolerance, and they often operate efficiently at room temperature with ambient air as the oxidant. These advances, together with their historical context and recent applications, are highlighted in this Minireview. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Diversity, Abundance, and Niche Differentiation of Ammonia-Oxidizing Prokaryotes in Mud Deposits of the Eastern China Marginal Seas

    PubMed Central

    Yu, Shaolan; Yao, Peng; Liu, Jiwen; Zhao, Bin; Zhang, Guiling; Zhao, Meixun; Yu, Zhigang; Zhang, Xiao-Hua

    2016-01-01

    The eastern China marginal seas (ECMS) are prominent examples of river-dominated ocean margins, whose most characteristic feature is the existence of isolated mud patches on sandy sediments. Ammonia-oxidizing prokaryotes play a crucial role in the nitrogen cycles of many marine environments, including marginal seas. However, few studies have attempted to address the distribution patterns of ammonia-oxidizing prokaryotes in mud deposits of these seas. The horizontal and vertical community composition and abundance of ammonia-oxidizing archaea (AOA) and bacteria (AOB) were investigated in mud deposits of the South Yellow Sea (SYS) and the East China Sea (ECS) by using amoA clone libraries and quantitative PCR. The diversity of AOB was comparable or higher in the mud zone of SYS and lower in ECS when compared with AOA. Vertically, surface sediments had generally higher diversity of AOA and AOB than middle and bottom layers. Diversity of AOA and AOB showed significant correlation with latitude. Nitrosopumilus and Nitrosospira lineages dominated AOA and AOB communities, respectively. Both AOA and AOB assemblages exhibited greater variations across different sites than those among various depths at one site. The abundance of bacterial amoA was generally higher than that of archaeal amoA, and both of them decreased with depth. Niche differentiation, which was affected by dissolved oxygen, salinity, ammonia, and silicate (SiO32-), was observed between AOA and AOB and among different groups of them. The spatial distribution of AOA and AOB was significantly correlated with δ15NTN and SiO32-, and nitrate and δ13C, respectively. Both archaeal and bacterial amoA abundance correlated strongly with SiO32-. This study improves our understanding of spatial distribution of AOA and AOB in ecosystems featuring oceanic mud deposits. PMID:26904010

  12. Diversity, Abundance, and Niche Differentiation of Ammonia-Oxidizing Prokaryotes in Mud Deposits of the Eastern China Marginal Seas.

    PubMed

    Yu, Shaolan; Yao, Peng; Liu, Jiwen; Zhao, Bin; Zhang, Guiling; Zhao, Meixun; Yu, Zhigang; Zhang, Xiao-Hua

    2016-01-01

    The eastern China marginal seas (ECMS) are prominent examples of river-dominated ocean margins, whose most characteristic feature is the existence of isolated mud patches on sandy sediments. Ammonia-oxidizing prokaryotes play a crucial role in the nitrogen cycles of many marine environments, including marginal seas. However, few studies have attempted to address the distribution patterns of ammonia-oxidizing prokaryotes in mud deposits of these seas. The horizontal and vertical community composition and abundance of ammonia-oxidizing archaea (AOA) and bacteria (AOB) were investigated in mud deposits of the South Yellow Sea (SYS) and the East China Sea (ECS) by using amoA clone libraries and quantitative PCR. The diversity of AOB was comparable or higher in the mud zone of SYS and lower in ECS when compared with AOA. Vertically, surface sediments had generally higher diversity of AOA and AOB than middle and bottom layers. Diversity of AOA and AOB showed significant correlation with latitude. Nitrosopumilus and Nitrosospira lineages dominated AOA and AOB communities, respectively. Both AOA and AOB assemblages exhibited greater variations across different sites than those among various depths at one site. The abundance of bacterial amoA was generally higher than that of archaeal amoA, and both of them decreased with depth. Niche differentiation, which was affected by dissolved oxygen, salinity, ammonia, and silicate (SiO[Formula: see text]), was observed between AOA and AOB and among different groups of them. The spatial distribution of AOA and AOB was significantly correlated with δ(15)NTN and SiO[Formula: see text], and nitrate and δ(13)C, respectively. Both archaeal and bacterial amoA abundance correlated strongly with SiO[Formula: see text]. This study improves our understanding of spatial distribution of AOA and AOB in ecosystems featuring oceanic mud deposits.

  13. Spatial distribution of total, ammonia-oxidizing, and denitrifying bacteria in biological wastewater treatment reactors for bioregenerative life support

    NASA Technical Reports Server (NTRS)

    Sakano, Yuko; Pickering, Karen D.; Strom, Peter F.; Kerkhof, Lee J.; Janes, H. W. (Principal Investigator)

    2002-01-01

    Bioregenerative life support systems may be necessary for long-term space missions due to the high cost of lifting supplies and equipment into orbit. In this study, we investigated two biological wastewater treatment reactors designed to recover potable water for a spacefaring crew being tested at Johnson Space Center. The experiment (Lunar-Mars Life Support Test Project-Phase III) consisted of four crew members confined in a test chamber for 91 days. In order to recycle all water during the experiment, an immobilized cell bioreactor (ICB) was employed for organic carbon removal and a trickling filter bioreactor (TFB) was utilized for ammonia removal, followed by physical-chemical treatment. In this study, the spatial distribution of various microorganisms within each bioreactor was analyzed by using biofilm samples taken from four locations in the ICB and three locations in the TFB. Three target genes were used for characterization of bacteria: the 16S rRNA gene for the total bacterial community, the ammonia monooxygenase (amoA) gene for ammonia-oxidizing bacteria, and the nitrous oxide reductase (nosZ) gene for denitrifying bacteria. A combination of terminal restriction fragment length polymorphism (T-RFLP), sequence, and phylogenetic analyses indicated that the microbial community composition in the ICB and the TFB consisted mainly of Proteobacteria, low-G+C gram-positive bacteria, and a Cytophaga-Flexibacter-Bacteroides group. Fifty-seven novel 16S rRNA genes, 8 novel amoA genes, and 12 new nosZ genes were identified in this study. Temporal shifts in the species composition of total bacteria in both the ICB and the TFB and ammonia-oxidizing and denitrifying bacteria in the TFB were also detected when the biofilms were compared with the inocula after 91 days. This result suggests that specific microbial populations were either brought in by the crew or enriched in the reactors during the course of operation.

  14. Evaluation of revised polymerase chain reaction primers for more inclusive quantification of ammonia-oxidizing archaea and bacteria.

    PubMed

    Meinhardt, Kelley A; Bertagnolli, Anthony; Pannu, Manmeet W; Strand, Stuart E; Brown, Sally L; Stahl, David A

    2015-04-01

    Ammonia-oxidizing archaea (AOA) and bacteria (AOB) fill key roles in the nitrogen cycle. Thus, well-vetted methods for characterizing their distribution are essential for framing studies of their significance in natural and managed systems. Quantification of the gene coding for one subunit of the ammonia monooxygenase (amoA) by polymerase chain reaction is frequently employed to enumerate the two groups. However, variable amplification of sequence variants comprising this conserved genetic marker for ammonia oxidizers potentially compromises within- and between-system comparisons. We compared the performance of newly designed non-degenerate quantitative polymerase chain reaction primer sets to existing primer sets commonly used to quantify the amoA of AOA and AOB using a collection of plasmids and soil DNA samples. The new AOA primer set provided improved quantification of model mixtures of different amoA sequence variants and increased detection of amoA in DNA recovered from soils. Although both primer sets for the AOB provided similar results for many comparisons, the new primers demonstrated increased detection in environmental application. Thus, the new primer sets should provide a useful complement to primers now commonly used to characterize the environmental distribution of AOA and AOB. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.

  15. Metabolic reprogramming during neuronal differentiation from aerobic glycolysis to neuronal oxidative phosphorylation.

    PubMed

    Zheng, Xinde; Boyer, Leah; Jin, Mingji; Mertens, Jerome; Kim, Yongsung; Ma, Li; Ma, Li; Hamm, Michael; Gage, Fred H; Hunter, Tony

    2016-06-10

    How metabolism is reprogrammed during neuronal differentiation is unknown. We found that the loss of hexokinase (HK2) and lactate dehydrogenase (LDHA) expression, together with a switch in pyruvate kinase gene splicing from PKM2 to PKM1, marks the transition from aerobic glycolysis in neural progenitor cells (NPC) to neuronal oxidative phosphorylation. The protein levels of c-MYC and N-MYC, transcriptional activators of the HK2 and LDHA genes, decrease dramatically. Constitutive expression of HK2 and LDHA during differentiation leads to neuronal cell death, indicating that the shut-off aerobic glycolysis is essential for neuronal survival. The metabolic regulators PGC-1α and ERRγ increase significantly upon neuronal differentiation to sustain the transcription of metabolic and mitochondrial genes, whose levels are unchanged compared to NPCs, revealing distinct transcriptional regulation of metabolic genes in the proliferation and post-mitotic differentiation states. Mitochondrial mass increases proportionally with neuronal mass growth, indicating an unknown mechanism linking mitochondrial biogenesis to cell size.

  16. Effects of acute ammonia toxicity on oxidative stress, immune response and apoptosis of juvenile yellow catfish Pelteobagrus fulvidraco and the mitigation of exogenous taurine.

    PubMed

    Zhang, Muzi; Li, Ming; Wang, Rixin; Qian, Yunxia

    2018-08-01

    Ammonia can easily form in intensive culture systems due to ammonification of uneaten food and animal excretion, which usually brings detrimental health effects to fish. However, little information is available on the mechanisms of the detrimental effects of ammonia stress and mitigate means in fish. In this study, the four experimental groups were carried out to test the response of yellow catfish to ammonia toxicity and their mitigation through taurine: group 1 was injected with NaCl, group 2 was injected with ammonium acetate, group 3 was injected with ammonium acetate and taurine, and group 4 was injected taurine. The results showed that ammonia poisoning could induce ammonia, glutamine, glutamate and malondialdehyde accumulation, and subsequently lead to blood deterioration (red blood cell, hemoglobin and serum biochemical index reduced), oxidative stress (superoxide dismutase and catalase activities declined) and immunosuppression (lysozyme, 50% hemolytic complement, total immunoglobulin, phagocytic index and respiratory burst reduced), but the exogenous taurine could mitigate the adverse effect of ammonia poisoning. In addition, ammonia poisoning could induce up-regulation of antioxidant enzymes (Cu/Zn-SOD, CAT, GPx and GR), inflammatory cytokines (TNF, IL-1 and IL-8) and apoptosis (p53, Bax, caspase 3 and caspase 9) genes transcription, suggesting that cell apoptotic and inflammation may relate to oxidative stress. This result will be helpful to understand the mechanism of aquatic toxicology induced by ammonia in fish. Copyright © 2018 Elsevier Ltd. All rights reserved.

  17. Copper-catalyzed aerobic oxidative synthesis of α-ketoamides from methyl ketones, amines and NIS at room temperature.

    PubMed

    Zhang, Juan; Wei, Ying; Lin, Shaoxia; Liang, Fushun; Liu, Pengjun

    2012-12-14

    A simple, efficient and practical copper-catalyzed aerobic oxidative synthesis of α-ketoamides from aryl methyl ketones, aliphatic amines and N-iodosuccinimide (NIS) has been developed. The one-pot reaction may proceed smoothly at room temperature in the open air. The possible mechanism for the formation of α-ketoamides was proposed. Molecular oxygen in air functions as both an oxidant and an oxygen source.

  18. Formation of Hydroxylamine on Dust Grains via Ammonia Oxidation

    NASA Astrophysics Data System (ADS)

    He, Jiao; Vidali, Gianfranco; Lemaire, Jean-Louis; Garrod, Robin T.

    2015-01-01

    The quest to detect prebiotic molecules in space, notably amino acids, requires an understanding of the chemistry involving nitrogen atoms. Hydroxylamine (NH2OH) is considered a precursor to the amino acid glycine. Although not yet detected, NH2OH is considered a likely target of detection with ALMA. We report on an experimental investigation of the formation of hydroxylamine on an amorphous silicate surface via the oxidation of ammonia. The experimental data are then fed into a simulation of the formation of NH2OH in dense cloud conditions. On ices at 14 K and with a modest activation energy barrier, NH2OH is found to be formed with an abundance that never falls below a factor 10 with respect to NH3. Suggestions of conditions for future observations are provided.

  19. [Characteristics of soil ammonia-oxidation microbial communities in different subtropical forests, China].

    PubMed

    Li, Yong-Chun; Liu, Bu-Rong; Guo, Shuai; Wu, Qi-Feng; Qin, Hua; Wu, Jia-Sen; Xu, Qiu-Fang

    2014-01-01

    To investigate the effects of different forest stands in subtropical China on the communities of soil ammonia-oxidizing microorganisms, we characterized the abundance of ammonia-oxidizing archaea (AOA) and bacteria (AOB), and the community structure of AOA in soils under stands of broad-leaved (BF) , Chinese fir (CF) , Pinus massoniana (PF) and moso bamboo (MB) forests using real-time quantitative PCR and denaturing gradient gel electrophoresis (DGGE). The results showed that the AOA gene copy numbers (1.62 x 10(6)-1.88 x 10(7) per gram of dry soil) were significantly higher than those of AOB genes (2.41 x 10(5)-4.36 x 10(5) per gram of dry soil). Significantly higher soil AOA abundance was detected in the MB than that in the CF (P < 0.05), and the latter was significantly higher than that in the BF and PF soils (P < 0.05). There were no significant differences in the soil AOB abundance among the four forest stands. As indicated by DGGE pattern, soil AOA species varied among the four forest stands. There was a difference in the soil AOA communities between the CF and MB stands. The AOA demonstrated a competitive advantage over the AOB in the soils under these major subtropical forests. Soil pH, concentrations of soil available potassium and organic carbon as well as the forest type were the main factors that influence the variation of AOA community structure and diversity.

  20. Responses of soil ammonia oxidizers to a short-term severe mercury stress.

    PubMed

    Zhou, Zhi-Feng; Liu, Yu-Rong; Sun, Guo-Xin; Zheng, Yuan-Ming

    2015-12-01

    The responses of soil ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) to mercury (Hg) stress were investigated through a short-term incubation experiment. Treated with four different concentrations of Hg (CK, Hg25, Hg50, and Hg100, denoting 0, 25, 50, and 100mgHg/kg dry soil, respectively), samples were harvested after 3, 7, and 28day incubation. Results showed that the soil potential nitrification rate (PNR) was significantly inhibited by Hg stress during the incubation. However, lower abundances of AOA (the highest in CK: 9.20×10(7)copies/g dry soil; the lowest in Hg50: 2.68×10(7)copies/g dry soil) and AOB (the highest in CK: 2.68×10(7)copies/g dry soil; the lowest in Hg50: 7.49×10(6)copies/g dry soil) were observed only at day 28 of incubation (P<0.05). Moreover, only the community structure of soil AOB obviously shifted under Hg stress as seen through DGGE profiles, which revealed that 2-3 distinct AOB bands emerged in the Hg treatments at day 28. In summary, soil PNR might be a very useful parameter to assess acute Hg stress on soil ecosystems, and the community structure of soil AOB might be a realistic biological indicator for the assessment of heavy metal stress on soil ecosystems in the future. Copyright © 2015. Published by Elsevier B.V.

  1. Effects of dicyandiamide and acetylene on N2O emissions and ammonia oxidizers in a fluvo-aquic soil applied with urea.

    PubMed

    Wang, Qing; Zhang, Li-Mei; Shen, Ju-Pei; Du, Shuai; Han, Li-Li; He, Ji-Zheng

    2016-11-01

    Ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) are crucial for N 2 O emission as they carry out the key step of nitrification. Dicyandiamide (DCD) and acetylene (C 2 H 2 ) are typical nitrification inhibitors (NIs), while the comparative effects of these NIs on N 2 O production and ammonia oxidizers' (AOB and AOA) growth are unclear. Four treatments including a control, urea, urea + DCD, and urea + C 2 H 2 were set up to investigate their effect of inhibiting soil nitrification, nitrification-related N 2 O emission as well as the growth of ammonia oxidizers with a fluvo-aquic soil using microcosms for 28 days. N 2 O emission and net nitrification rate increased after the application of urea, but were significantly restrained in urea + NI treatments, while C 2 H 2 was more effective in reducing N 2 O emission and nitrification rate than DCD. The abundance of AOB, which was significantly correlated with N 2 O emission and net nitrification rate, was more inhibited by C 2 H 2 than DCD. Furthermore, the application of urea in all the soils had little impact on the AOA community, while obvious shifts of AOB community structure were found compared with the control. All AOB sequences fell within Nitrosospira cluster 3, and the AOA community was clustered to group 1.1b. Collectively, it indicated that application of urea combined with NIs (DCD or C 2 H 2 ) could potentially alter N 2 O emission, mainly through regulating the growth of AOB but not AOA in this fluvo-aquic soil.

  2. Reduced graphene oxide-rose bengal hybrid film for improved ammonia detection with low humidity interference at room temperature

    NASA Astrophysics Data System (ADS)

    Midya, Anupam; Ghosh, Ruma; Santra, Sumita; Ray, Samit K.; Guha, Prasanta K.

    2016-02-01

    Development of chemoresistive ammonia sensor that does not suffer with humidity interference is highly desirable for practical environmental monitoring systems. We report enhanced ammonia sensing using chemically reduced graphene oxide (RGO) and rose bengal (RB) nanocomposite fabricated in a very simple and cost effective manner. The RGO-RB nanocomposites were synthesized using three different concentrations (2 mg mL-1, 5 mg mL-1 and 10 mg mL-1) of RB keeping the RGO concentration same. Ammonia and humidity sensing of these three different composites were explored. Interestingly, it was observed that with increasing concentration of RB, the sensitivity of the sensor towards ammonia was increased but the sensitivity towards humidity was decreased. The response of the nanocomposites varied from ˜9-45% against 400-2800 ppm of ammonia whereas intrinsic RGO showed a response of merely 17% against 2800 ppm of ammonia. On the other hand the response of the nanocomposite based sensor was reduced from 18% to 7% against 100% relative humidity. Also, the sensor was found to be selective towards ammonia when tested against other toxic volatile organic compounds. The limit of detection of the RGO-RB based sensor was calculated to be as low as 0.9 ppm. Field emission scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy and UV-vis spectroscopy were carried out for the detailed structural characterizations of the sensing layer. These results are believed to be very useful for the cost effective fabrication of graphene based ammonia sensors which have reduced effects of humidity.

  3. Dominance of ammonia-oxidizing archaea community induced by land use change from Masson pine to eucalypt plantation in subtropical China.

    PubMed

    Zhang, Fang-Qiu; Pan, Wen; Gu, Ji-Dong; Xu, Bin; Zhang, Wei-Hua; Zhu, Bao-Zhu; Wang, Yu-Xia; Wang, Yong-Feng

    2016-08-01

    A considerable proportion of Masson pine forests have been converted into eucalypt plantations in the last 30 years in Guangdong Province, subtropical China, for economic reasons, which may affect the ammonia-oxidizing archaea (AOA) community and the process of ammonia transformation. In order to determine the effects of forest conversion on AOA community, AOA communities in a Masson pine (Pinus massoniana) plantation and a eucalypt (Eucalyptus urophylla) plantation, which was converted from the Masson pine, were compared. Results showed that the land use change from the Masson pine to the eucalypt plantation decreased soil nutrient levels. A significant decrease of the potential nitrification rates (PNR) was also observed after the forest conversion (p < 5 %, n = 6). AOA were the only ammonia oxidizers in both plantations (no ammonia-oxidizing bacteria were detected). The detected AOA are affiliated with the genera Nitrosotalea and Nitrososphaera. A decrease of AOA abundance and an increase of the diversity were evident with the plantation conversion in the surface layer. AOA amoA gene diversity was negatively correlated with organic C and total N, respectively (p < 0.05, n = 12). AOA amoA gene abundance was negatively correlated with NH4 (+) and available P, respectively (p < 0.05, n = 12). However, AOA abundance was positively correlated with PNR, but not significantly (p < 0.05, n = 6), indicating AOA community change was only a partial reason for the decrease of PNR.

  4. Concentrations and emission rates of aerial ammonia, nitrous oxide, methane, carbon dioxide, dust and endotoxin in UK broiler and layer houses.

    PubMed

    Wathes, C M; Holden, M R; Sneath, R W; White, R P; Phillips, V R

    1997-03-01

    1. A survey of the concentration and emission rates of aerial ammonia, nitrous oxide, methane, carbon dioxide, dust and endotoxin was undertaken in 4 examples each of typical UK broiler, cage and perchery houses over 24 h during winter and summer. 2. Overall the air quality within the poultry houses was unsatisfactory as judged by the dual criteria of farmer health and bird performance. 3. Mean concentrations of ammonia ranged from 12.3 to 24.2 ppm while concentrations of methane and nitrous oxide were close to ambient levels. Mass concentrations of aerial dust ranged from 2 to 10 mg/m3 and 0.3 to 1.2 mg/m3 for inspirable and respirable fractions respectively, while endotoxin concentration was typically about 0.1 microgram/m3 (inspirable fraction). 4. Emission rates of gaseous ammonia were rapid (9.2 g (NH3)/h per 500 kg live body weight) and uniform across the three types of building, while emissions of methane and nitrous oxide were slow. Rates of dust emission ranged from 0.86 to 8.24 g/h per 500 kg live body weight in the inspirable size fraction.

  5. Discovery of a metalloenzyme-like cooperative catalytic system of metal nanoclusters and catechol derivatives for the aerobic oxidation of amines.

    PubMed

    Yuan, Hao; Yoo, Woo-Jin; Miyamura, Hiroyuki; Kobayashi, Shū

    2012-08-29

    We have discovered a new class of cooperative catalytic system, consisting of heterogeneous polymer-immobilized bimetallic Pt/Ir alloyed nanoclusters (NCs) and 4-tert-butylcatechol, for the aerobic oxidation of amines to imines under ambient conditions. After optimization, the desired imines were obtained in good to excellent yields with broad substrate scope. The reaction rate was determined to be first-order with respect to the substrate and catechol and zero-order for the alloyed Pt/Ir NC catalyst. Control studies revealed that both the heterogeneous NC catalyst and 4-tert-butylcatechol are essential and act cooperatively to facilitate the aerobic oxidation under mild conditions.

  6. Responses of soil hydrolytic enzymes, ammonia-oxidizing bacteria and archaea to nitrogen applications in a temperate grassland in Inner Mongolia.

    PubMed

    Zhang, Xinyu; Tang, Yuqian; Shi, Yao; He, Nianpeng; Wen, Xuefa; Yu, Qiang; Zheng, Chunyu; Sun, Xiaomin; Qiu, Weiwen

    2016-09-06

    We used a seven-year urea gradient applied field experiment to investigate the effects of nitrogen (N) applications on soil N hydrolytic enzyme activity and ammonia-oxidizing microbial abundance in a typical steppe ecosystem in Inner Mongolia. The results showed that N additions inhibited the soil N-related hydrolytic enzyme activities, especially in 392 kg N ha(-1 )yr(-1) treatment. As N additions increased, the amoA gene copy ratios of ammonia-oxidizing archaea (AOA) to ammonia-oxidizing bacteria (AOB) decreased from 1.13 to 0.65. Pearson correlation analysis showed that the AOA gene copies were negatively related with NH4(+)-N content. However, the AOB gene copies were positively correlated with NO3(-)-N content. Moderate N application rates (56-224 kg N ha(-1 )yr(-1)) accompanied by P additions are beneficial to maintaining the abundance of AOB, as opposed to the inhibition of highest N application rate (392 kg N ha(-1 )yr(-1)) on the abundance of AOB. This study suggests that the abundance of AOB and AOA would not decrease unless N applications exceed 224 kg N ha(-1 )yr(-1) in temperate grasslands in Inner Mongolia.

  7. Cu(II)-catalyzed esterification reaction via aerobic oxidative cleavage of C(CO)-C(alkyl) bonds.

    PubMed

    Ma, Ran; He, Liang-Nian; Liu, An-Hua; Song, Qing-Wen

    2016-02-04

    A novel Cu(II)-catalyzed aerobic oxidative esterification of simple ketones for the synthesis of esters has been developed with wide functional group tolerance. This process is assumed to go through a tandem sequence consisting of α-oxygenation/esterification/nucleophilic addition/C-C bond cleavage and carbon dioxide is released as the only byproduct.

  8. Remarkable biomimetic chemoselective aerobic oxidation of flavano-ellagitannins found in oak-aged wine.

    PubMed

    Petit, Emilie; Lefeuvre, Dorothée; Jacquet, Rémi; Pouységu, Laurent; Deffieux, Denis; Quideau, Stéphane

    2013-10-25

    Under the auspices of Bacchus! Acutissimins, natural flavano-ellagitannins, occur in oak-aged wine as a result of a diastereoselective condensation reaction of the flavan-3-ol catechin, a component of grapes, with the C-glucosidic ellagitannin vescalagin, found in oak. The acutissimins are further converted into natural mongolicains and analogues of camelliatannin G in a remarkably chemoselective fashion by simple aerobic oxidation. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Changing roles of ammonia-oxidizing bacteria and archaea in a continuously acidifying soil caused by over-fertilization with nitrogen.

    PubMed

    Song, He; Che, Zhao; Cao, Wenchao; Huang, Ting; Wang, Jingguo; Dong, Zhaorong

    2016-06-01

    Nitrification coupled with nitrate leaching contributes to soil acidification. However, little is known about the effect of soil acidification on nitrification, especially on ammonia oxidation that is the rate-limiting step of nitrification and performed by ammonia-oxidizing bacteria (AOB) and archaea (AOA). Serious soil acidification occurs in Chinese greenhouses due to the overuse of N-fertilizer. In the present study, greenhouse soils with 1, 3, 5, 7, and 9 years of vegetable cultivation showed a consistent pH decline (i.e., 7.0, 6.3, 5.6, 4.9, and 4.3). Across the pH gradient, we analyzed the community structure and abundance of AOB and AOA by pyrosequencing and real-time PCR techniques, respectively. The recovered nitrification potential (RNP) method was used to determine relative contributions of AOA and AOB to nitrification potential. The results revealed that soil acidification shaped the community structures of AOA and AOB. In acidifying soil, soil pH, NH3 concentration, and DOC content were critical factors shaping ammonia oxidizer community structure. AOB abundance, but not AOA, was strongly influenced by soil acidification. When soil pH was below 5.0, AOA rather than AOB were responsible for almost all of the RNP. However, when soil pH ranged from 5.6 to 7.0, AOB were the major contributors to RNP. The group I.1a-associatied AOA had more relative abundance in low pH (pH<6.3), whereas group I.1b tended to prefer neutral pH. Clusters 2, 10, and 12 in AOB were more abundant in acidic soil (pH <5.6), while Nitrosomonas-like lineage and unclassified lineage 3 were prevailing in neutral soil and slightly acidic soil (pH, 6.0-6.5), respectively. These results suggested that soil acidification had a profound impact on ammonia oxidation and more specific lineages in AOB occupying different pH-associated niches required further investigation.

  10. Copper(I)/TEMPO Catalyzed Aerobic Oxidation of Primary Alcohols to Aldehydes with Ambient Air

    PubMed Central

    Hoover, Jessica M.; Steves, Janelle E.; Stahl, Shannon S.

    2012-01-01

    This protocol describes a practical laboratory-scale method for aerobic oxidation of primary alcohols to aldehydes, using a chemoselective CuI/TEMPO catalyst system. The catalyst is prepared in situ from commercially available reagents, and the reactions are performed in a common organic solvent (acetonitrile) with ambient air as the oxidant. Three different reaction conditions and three procedures for the isolation and purification of the aldehyde product are presented. The oxidations of eight different alcohols, described here, include representative examples of each reaction condition and purification method. Reaction times vary from 20 min to 24 h, depending on the alcohol, while the purification methods each take about 2 h. The total time necessary for the complete protocol ranges from 3 – 26 h. PMID:22635108

  11. Control strategies for nitrous oxide emissions reduction on wastewater treatment plants operation.

    PubMed

    Santín, I; Barbu, M; Pedret, C; Vilanova, R

    2017-11-15

    The present paper focused on reducing greenhouse gases emissions in wastewater treatment plants operation by application of suitable control strategies. Specifically, the objective is to reduce nitrous oxide emissions during the nitrification process. Incomplete nitrification in the aerobic tanks can lead to an accumulation of nitrite that triggers the nitrous oxide emissions. In order to avoid the peaks of nitrous oxide emissions, this paper proposes a cascade control configuration by manipulating the dissolved oxygen set-points in the aerobic tanks. This control strategy is combined with ammonia cascade control already applied in the literature. This is performed with the objective to take also into account effluent pollutants and operational costs. In addition, other greenhouse gases emissions sources are also evaluated. Results have been obtained by simulation, using a modified version of Benchmark Simulation Model no. 2, which takes into account greenhouse gases emissions. This is called Benchmark Simulation Model no. 2 Gas. The results show that the proposed control strategies are able to reduce by 29.86% of nitrous oxide emissions compared to the default control strategy, while maintaining a satisfactory trade-off between water quality and costs. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Nitrification rates in Arctic soils are associated with functionally distinct populations of ammonia-oxidizing archaea

    NASA Astrophysics Data System (ADS)

    Alves, Ricardo J. E.; Wanek, Wolfgang; Zappe, Anna; Richter, Andreas; Svenning, Mette M.; Schleper, Christa; Urich, Tim

    2014-05-01

    The functioning of Arctic soil ecosystems is crucially important for global climate, although basic knowledge regarding their biogeochemical processes is lacking. Nitrogen (N) is the major limiting nutrient in these environments, and therefore it is particularly important to gain a better understanding of the microbial populations catalyzing transformations that influence N bioavailability. However, microbial communities driving this process remain largely uncharacterized in Arctic soils, namely those catalyzing the rate-limiting step of ammonia (NH3) oxidation. Eleven Arctic soils from Svalbard were analyzed through a polyphasic approach, including determination of gross nitrification rates through a 15N pool dilution method, qualitative and quantitative analyses of ammonia-oxidizing archaea (AOA) and bacteria (AOB) populations based on the functional marker gene amoA (encoding the ammonia monooxygenase subunit A), and enrichment of AOA in laboratory cultures. AOA were the only NH3 oxidizers detected in five out of 11 soils, and outnumbered AOB by 1 to 3 orders of magnitude in most others. AOA showed a great overall phylogenetic diversity that was differentially distributed across soil ecosystems, and exhibited an uneven population composition that reflected the dominance of a single AOA phylotype in each population. Moreover, AOA populations showed a multifactorial association with the soil properties, which reflected an overall distribution associated with tundra type and with several physico-chemical parameters combined, namely pH and soil moisture and N contents (i.e., NO3- and dissolved organic N). Remarkably, the different gross in situ and potential nitrification rates between soils were associated with distinct AOA phylogenetic clades, suggesting differences in their nitrifying potential, both under the native NH3 conditions and as a response to higher NH3 availability. This was further supported by the selective enrichment of two AOA clades that exhibited

  13. Molecular characterization of a microbial consortium involved in methane oxidation coupled to denitrification under micro-aerobic conditions.

    PubMed

    Liu, Jingjing; Sun, Faqian; Wang, Liang; Ju, Xi; Wu, Weixiang; Chen, Yingxu

    2014-01-01

    Methane can be used as an alternative carbon source in biological denitrification because it is nontoxic, widely available and relatively inexpensive. A microbial consortium involved in methane oxidation coupled to denitrification (MOD) was enriched with nitrite and nitrate as electron acceptors under micro-aerobic conditions. The 16S rRNA gene combined with pmoA phylogeny of methanotrophs and nirK phylogeny of denitrifiers were analysed to reveal the dominant microbial populations and functional microorganisms. Real-time quantitative polymerase chain reaction results showed high numbers of methanotrophs and denitrifiers in the enriched consortium. The 16S rRNA gene clone library revealed that Methylococcaceae and Methylophilaceae were the dominant populations in the MOD ecosystem. Phylogenetic analyses of pmoA gene clone libraries indicated that all methanotrophs belonged to Methylococcaceae, a type I methanotroph employing the ribulose monophosphate pathway for methane oxidation. Methylotrophic denitrifiers of the Methylophilaceae that can utilize organic intermediates (i.e. formaldehyde, citrate and acetate) released from the methanotrophs played a vital role in aerobic denitrification. This study is the first report to confirm micro-aerobic denitrification and to make phylogenetic and functional assignments for some members of the microbial assemblages involved in MOD. © 2013 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

  14. Na-K-Cl Cotransporter-1 in the Mechanism of Ammonia-induced Astrocyte Swelling*

    PubMed Central

    Jayakumar, Arumugam R.; Liu, Mingli; Moriyama, Mitsuaki; Ramakrishnan, Ramugounder; Forbush, Bliss; Reddy, Pichili V. B.; Norenberg, Michael D.

    2008-01-01

    Brain edema and the consequent increase in intracranial pressure and brain herniation are major complications of acute liver failure (fulminant hepatic failure) and a major cause of death in this condition. Ammonia has been strongly implicated as an important factor, and astrocyte swelling appears to be primarily responsible for the edema. Ammonia is known to cause cell swelling in cultured astrocytes, although the means by which this occurs has not been fully elucidated. A disturbance in one or more of these systems may result in loss of ion homeostasis and cell swelling. In particular, activation of the Na-K-Cl cotransporter (NKCC1) has been shown to be involved in cell swelling in several neurological disorders. We therefore examined the effect of ammonia on NKCC activity and its potential role in the swelling of astrocytes. Cultured astrocytes were exposed to ammonia (NH4Cl; 5 mm), and NKCC activity was measured. Ammonia increased NKCC activity at 24 h. Inhibition of this activity by bumetanide diminished ammonia-induced astrocyte swelling. Ammonia also increased total as well as phosphorylated NKCC1. Treatment with cyclohexamide, a potent inhibitor of protein synthesis, diminished NKCC1 protein expression and NKCC activity. Since ammonia is known to induce oxidative/nitrosative stress, and antioxidants and nitric-oxide synthase inhibition diminish astrocyte swelling, we also examined whether ammonia caused oxidation and/or nitration of NKCC1. Cultures exposed to ammonia increased the state of oxidation and nitration of NKCC1, whereas the antioxidants N-nitro-l-arginine methyl ester and uric acid all significantly diminished NKCC activity. These agents also reduced phosphorylated NKCC1 expression. These results suggest that activation of NKCC1 is an important factor in the mediation of astrocyte swelling by ammonia and that such activation appears to be mediated by NKCC1 abundance as well as by its oxidation/nitration and phosphorylation. PMID:18849345

  15. High-Potential Electrocatalytic O2 Reduction with Nitroxyl/NOx Mediators: Implications for Fuel Cells and Aerobic Oxidation Catalysis

    PubMed Central

    2015-01-01

    Efficient reduction of O2 to water is a central challenge in energy conversion and many aerobic oxidation reactions. Here, we show that the electrochemical oxygen reduction reaction (ORR) can be achieved at high potentials by using soluble organic nitroxyl and nitrogen oxide (NOx) mediators. When used alone, neither organic nitroxyls, such as 2,2,6,6-tetramethyl-1-piperidinyl-N-oxyl (TEMPO), nor NOx species, such as sodium nitrite, are effective ORR mediators. The combination of nitroxyl/NOx species, however, mediates sustained O2 reduction with overpotentials as low as 300 mV in acetonitrile containing trifluoroacetic acid. Mechanistic analysis of the coupled redox reactions supports a process in which the nitrogen oxide catalyst drives aerobic oxidation of a nitroxyl mediator to an oxoammonium species, which then is reduced back to the nitroxyl at the cathode. The electrolysis potential is dictated by the oxoammonium/nitroxyl reduction potential. The overpotentials accessible with this ORR system are significantly lower than widely studied molecular metal-macrocycle ORR catalysts and benefit from the mechanism-based specificity for four-electron reduction of oxygen to water mediated by NOx species, together with kinetically efficient reduction of oxidized NOx species by TEMPO and other organic nitroxyls. PMID:27162977

  16. Temperature-Dependent Kinetic Study of Ammonia Oxidation Reaction on Gas Diffusion Electrodes in NH 3-Saturated 1 M KOH Solutions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Liang, Z.; Song, L.; Ma, Z.

    Ammonia oxidation reaction (AOR) is sluggish, especially at ambient temperature. To make kinetic study in electrochemical cell more informative and relevant to the catalysts’ performance in direct ammonia fuel cells (DAFCs) operating at about 100°C, it is desirable to study the AOR kinetics at elevated temperatures. However, ammonia evaporation accelerates with increasing temperature causing decrease of ammonia concentration with time. Here, we show a feasible solution to this issue - let argon gas bubble through concentrated ammonia before entering the electrochemical cell so that the solution can be kept ammonia saturated and oxygen free. Repeatable AOR polarization curves were obtainedmore » at temperatures up to 60°C. The AOR activities are characterized by the average currents at 0.5 V versus RHE measured at 20 mV s-1 in potential cycles below the potential of peak current. For PtIr/C, the PGM mass activities are 25 A g-1 at 25°C and 225 A g -1 at 60°C. The results for Pt/C and Ir/C and discussion of the causes for their distinct kinetic behavior will be presented at the meeting.« less

  17. Temperature-Dependent Kinetic Study of Ammonia Oxidation Reaction on Gas Diffusion Electrodes in NH 3-Saturated 1 M KOH Solutions

    DOE PAGES

    Liang, Z.; Song, L.; Ma, Z.; ...

    2018-04-01

    Ammonia oxidation reaction (AOR) is sluggish, especially at ambient temperature. To make kinetic study in electrochemical cell more informative and relevant to the catalysts’ performance in direct ammonia fuel cells (DAFCs) operating at about 100°C, it is desirable to study the AOR kinetics at elevated temperatures. However, ammonia evaporation accelerates with increasing temperature causing decrease of ammonia concentration with time. Here, we show a feasible solution to this issue - let argon gas bubble through concentrated ammonia before entering the electrochemical cell so that the solution can be kept ammonia saturated and oxygen free. Repeatable AOR polarization curves were obtainedmore » at temperatures up to 60°C. The AOR activities are characterized by the average currents at 0.5 V versus RHE measured at 20 mV s-1 in potential cycles below the potential of peak current. For PtIr/C, the PGM mass activities are 25 A g-1 at 25°C and 225 A g -1 at 60°C. The results for Pt/C and Ir/C and discussion of the causes for their distinct kinetic behavior will be presented at the meeting.« less

  18. Modeling of nitrous oxide production by autotrophic ammonia-oxidizing bacteria with multiple production pathways.

    PubMed

    Ni, Bing-Jie; Peng, Lai; Law, Yingyu; Guo, Jianhua; Yuan, Zhiguo

    2014-04-01

    Autotrophic ammonia oxidizing bacteria (AOB) have been recognized as a major contributor to N2O production in wastewater treatment systems. However, so far N2O models have been proposed based on a single N2O production pathway by AOB, and there is still a lack of effective approach for the integration of these models. In this work, an integrated mathematical model that considers multiple production pathways is developed to describe N2O production by AOB. The pathways considered include the nitrifier denitrification pathway (N2O as the final product of AOB denitrification with NO2(-) as the terminal electron acceptor) and the hydroxylamine (NH2OH) pathway (N2O as a byproduct of incomplete oxidation of NH2OH to NO2(-)). In this model, the oxidation and reduction processes are modeled separately, with intracellular electron carriers introduced to link the two types of processes. The model is calibrated and validated using experimental data obtained with two independent nitrifying cultures. The model satisfactorily describes the N2O data from both systems. The model also predicts shifts of the dominating pathway at various dissolved oxygen (DO) and nitrite levels, consistent with previous hypotheses. This unified model is expected to enhance our ability to predict N2O production by AOB in wastewater treatment systems under varying operational conditions.

  19. The effect of widespread early aerobic marine ecosystems on methane cycling and the Great Oxidation

    NASA Astrophysics Data System (ADS)

    Daines, Stuart J.; Lenton, Timothy M.

    2016-01-01

    The balance of evidence suggests that oxygenic photosynthesis had evolved by 3.0-2.7 Ga, several hundred million years prior to the Great Oxidation ≈2.4 Ga. Previous work has shown that if oxygenic photosynthesis spread globally prior to the Great Oxidation, this could have supported widespread aerobic ecosystems in the surface ocean, without oxidising the atmosphere. Here we use a suite of models to explore the implications for carbon cycling and the Great Oxidation. We find that recycling of oxygen and carbon within early aerobic marine ecosystems would have restricted the balanced fluxes of methane and oxygen escaping from the ocean, lowering the atmospheric concentration of methane in the Great Oxidation transition and its aftermath. This in turn would have minimised any bi-stability of atmospheric oxygen, by weakening a stabilising feedback on oxygen from hydrogen escape to space. The result would have been a more reversible and probably episodic rise of oxygen at the Great Oxidation transition, consistent with existing geochemical evidence. The resulting drop in methane levels to ≈10 ppm is consistent with climate cooling at the time but adds to the puzzle of what kept the rest of the Proterozoic warm. A key test of the scenario of abundant methanotrophy in oxygen oases before the Great Oxidation is its predicted effects on the organic carbon isotope (δ13Corg) record. Our open ocean general circulation model predicts δC13org ≈ - 30 to -45‰ consistent with most data from 2.65 to 2.45 Ga. However, values of δC13org ≈ - 50 ‰ require an extreme scenario such as concentrated methanotroph production where shelf-slope upwelling of methane-rich water met oxic shelf water.

  20. Enhanced ammonia removal at room temperature by pH controlled partial nitrification and subsequent anaerobic ammonium oxidation.

    PubMed

    Durán, U; del Val Río, A; Campos, J L; Mosquera-Corral, A; Méndez, R

    2014-01-01

    The Anammox-based processes are suitable for the treatment of wastewaters characterized by a low carbon to nitrogen (C/N) ratio. The application of the Anammox process requires the availability of an effluent with a NO2- -N/NH4+ -N ratio composition around 1 g g-1, which involves the necessity of a previous step where the partial nitrification is performed. In this step, the inhibition of the nitrite-oxidizing bacteria (NOB) is crucial. In the present work, a combined partial nitrification-ANaerobic AMmonia OXidation (Anammox) two-units system operated at room temperature (20 degreeC) has been tested for the nitrogen removal of pre-treated pig slurry. To achieve the successful partial nitrification and inhibit the NOB activity, different ammonium/inorganic carbon (NH4+/IC) ratios were assayed from 1.19 to 0.82g NH4+-Ng-1 HCO3-C. This procedure provoked a decrease of the pH value to 6.0 to regulate the inhibitory effect over ammonia-oxidizing bacteria caused by free ammonia. Simultaneously, the NOB experienced the inhibitory effect of free nitrous acid which avoided the presence of nitrate in the effluent. The NH4+/IC ratio which allowed the obtaining of the desired effluent composition (50% of both ammonium and nitrite) was 0.82 +/- 0.02 g NH4+-N g-1 HCO3- -C. The Anammox reactor was fed with the effluent of the partial nitrification unit containing a NO2 -N/NH4+ -N ratio of 1 g g-1' where a nitrogen loading rate of 0.1 g N L-1 d-1 was efficiently removed.

  1. Toxic effects of butyl elastomers on aerobic methane oxidation

    NASA Astrophysics Data System (ADS)

    Niemann, Helge; Steinle, Lea I.; Blees, Jan H.; Krause, Stefan; Bussmann, Ingeborg; Lehmann, Moritz F.; Treude, Tina

    2013-04-01

    Large quantities of the potent greenhouse gas methane are liberated into the water column of marine and lacustrine environments where it may be consumed by aerobic methane oxidising bacteria before reaching the atmosphere.The reliable quantification of aerobic methane oxidation (MOx) rates is consequently of paramount importance for estimating methane budgets and to understand the controls on water column methane cycling. A widely used set of methods for measuring MOx rates is based on the incubation of water samples during which the consumption of methane is monitored, for instance with radio-tracer assays. Typically, incubation vessels are sealed with butyl rubber stoppers because these elastomers are essentially impermeable for gases at the relevant time scales. We tested the effect of different stopper materials (unmodified- and halogenated butyl rubber) on MOx activity in environmental samples and in cultures of methane oxidising bacteria. MOx rates in samples sealed with unmodified butyl rubber were > 75% lower compared to parallel incubations with halogenated butyl rubber seals, suggesting inhibiting/toxic effects associated with the use of unmodified butyl elastomers. To further explore the cause of these effects, we analysed aqueous extracts of the different stoppers. Halogenated butyl rubber stoppers appeared to bleed off comparably little amounts of organics. In stark contrast, extracts of unmodified butyl rubber were contaminated with various organic compounds including potential bactericides such as benzyltoluenes, phenylalkanes and benzuothiazoles. We also found tetramethylthiourea, a scavenger of active oxygen species, which may inhibit the MOx pathway.

  2. Bilogical Treatment for Ammonia Oxidation in Drinking Water Facilities

    EPA Science Inventory

    Ammonia is an unregulated compound, but is naturally occurring in many drinking water sources. It is also used by some treatment facilities to produce chloramines for disinfection purposes. Because ammonia is non-toxic, its presence in drinking water is often disregarded. Thro...

  3. Alkaline Ammonia Electrolysis on Electrodeposited Platinum for Controllable Hydrogen Production.

    PubMed

    Gwak, Jieun; Choun, Myounghoon; Lee, Jaeyoung

    2016-02-19

    Ammonia is beginning to attract a great deal of attention as an alternative energy source carrier, because clean hydrogen can be produced through electrolytic processes without the emission of COx . In this study, we deposited various shapes of Pt catalysts under potentiostatic mode; the electrocatalytic oxidation behavior of ammonia using these catalysts was studied in alkaline media. The electrodeposited Pt was characterized by both qualitative and quantitative analysis. To discover the optimal structure and the effect of ammonia concentration, the bulk pH value, reaction temperature, and applied current of ammonia oxidation were investigated using potential sweep and galvanostatic methods. Finally, ammonia electrolysis was conducted using a zero-gap cell, producing highly pure hydrogen with an energy efficiency over 80 %. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Differential distribution patterns of ammonia-oxidizing archaea and bacteria in acidic soils of Nanling National Nature Reserve forests in subtropical China.

    PubMed

    Gan, Xian-Hua; Zhang, Fang-Qiu; Gu, Ji-Dong; Guo, Yue-Dong; Li, Zhao-Qing; Zhang, Wei-Qiang; Xu, Xiu-Yu; Zhou, Yi; Wen, Xiao-Ying; Xie, Guo-Guang; Wang, Yong-Feng

    2016-02-01

    In addition to ammonia-oxidizing bacteria (AOB) the more recently discovered ammonia-oxidizing archaea (AOA) can also oxidize ammonia, but little is known about AOA community structure and abundance in subtropical forest soils. In this study, both AOA and AOB were investigated with molecular techniques in eight types of forests at surface soils (0-2 cm) and deep layers (18-20 cm) in Nanling National Nature Reserve in subtropical China. The results showed that the forest soils, all acidic (pH 4.24-5.10), harbored a wide range of AOA phylotypes, including the genera Nitrosotalea, Nitrososphaera, and another 6 clusters, one of which was reported for the first time. For AOB, only members of Nitrosospira were retrieved. Moreover, the abundance of the ammonia monooxygenase gene (amoA) from AOA dominated over AOB in most soil samples (13/16). Soil depth, rather than forest type, was an important factor shaping the community structure of AOA and AOB. The distribution patterns of AOA and AOB in soil layers were reversed: AOA diversity and abundances in the deep layers were higher than those in the surface layers; on the contrary, AOB diversity and abundances in the deep layers were lower than those in the surface layers. Interestingly, the diversity of AOA was positively correlated with pH, but negatively correlated with organic carbon, total nitrogen and total phosphorus, and the abundance of AOA was negatively correlated with available phosphorus. Our results demonstrated that AOA and AOB were differentially distributed in acidic soils in subtropical forests and affected differently by soil characteristics.

  5. Environmental factors determining ammonia-oxidizing organism distribution and diversity in marine environments.

    PubMed

    Bouskill, Nicholas J; Eveillard, Damien; Chien, Diana; Jayakumar, Amal; Ward, Bess B

    2012-03-01

    Ammonia-oxidizing bacteria (AOB) and archaea (AOA) play a vital role in bridging the input of fixed nitrogen, through N-fixation and remineralization, to its loss by denitrification and anammox. Yet the major environmental factors determining AOB and AOA population dynamics are little understood, despite both groups having a wide environmental distribution. This study examined the relative abundance of both groups of ammonia-oxidizing organisms (AOO) and the diversity of AOA across large-scale gradients in temperature, salinity and substrate concentration and dissolved oxygen. The relative abundance of AOB and AOA varied across environments, with AOB dominating in the freshwater region of the Chesapeake Bay and AOA more abundant in the water column of the coastal and open ocean. The highest abundance of the AOA amoA gene was recorded in the oxygen minimum zones (OMZs) of the Eastern Tropical South Pacific (ETSP) and the Arabian Sea (AS). The ratio of AOA : AOB varied from 0.7 in the Chesapeake Bay to 1600 in the Sargasso Sea. Relative abundance of both groups strongly correlated with ammonium concentrations. AOA diversity, as determined by phylogenetic analysis of clone library sequences and archetype analysis from a functional gene DNA microarray, detected broad phylogenetic differences across the study sites. However, phylogenetic diversity within physicochemically congruent stations was more similar than would be expected by chance. This suggests that the prevailing geochemistry, rather than localized dispersal, is the major driving factor determining OTU distribution. © 2011 Society for Applied Microbiology and Blackwell Publishing Ltd.

  6. Candidatus Nitrosocaldus cavascurensis, an Ammonia Oxidizing, Extremely Thermophilic Archaeon with a Highly Mobile Genome

    PubMed Central

    Abby, Sophie S.; Melcher, Michael; Kerou, Melina; Krupovic, Mart; Stieglmeier, Michaela; Rossel, Claudia; Pfeifer, Kevin; Schleper, Christa

    2018-01-01

    Ammonia oxidizing archaea (AOA) of the phylum Thaumarchaeota are widespread in moderate environments but their occurrence and activity has also been demonstrated in hot springs. Here we present the first enrichment of a thermophilic representative with a sequenced genome, which facilitates the search for adaptive strategies and for traits that shape the evolution of Thaumarchaeota. Candidatus Nitrosocaldus cavascurensis has been enriched from a hot spring in Ischia, Italy. It grows optimally at 68°C under chemolithoautotrophic conditions on ammonia or urea converting ammonia stoichiometrically into nitrite with a generation time of approximately 23 h. Phylogenetic analyses based on ribosomal proteins place the organism as a sister group to all known mesophilic AOA. The 1.58 Mb genome of Ca. N. cavascurensis harbors an amoAXCB gene cluster encoding ammonia monooxygenase and genes for a 3-hydroxypropionate/4-hydroxybutyrate pathway for autotrophic carbon fixation, but also genes that indicate potential alternative energy metabolisms. Although a bona fide gene for nitrite reductase is missing, the organism is sensitive to NO-scavenging, underlining the potential importance of this compound for AOA metabolism. Ca. N. cavascurensis is distinct from all other AOA in its gene repertoire for replication, cell division and repair. Its genome has an impressive array of mobile genetic elements and other recently acquired gene sets, including conjugative systems, a provirus, transposons and cell appendages. Some of these elements indicate recent exchange with the environment, whereas others seem to have been domesticated and might convey crucial metabolic traits. PMID:29434576

  7. Effects of different fertilizers on the abundance and community structure of ammonia oxidizers in a yellow clay soil.

    PubMed

    Yao, Huaiying; Huang, Sha; Qiu, Qiongfen; Li, Yaying; Wu, Lianghuan; Mi, Wenhai; Dai, Feng

    2016-08-01

    Yellow clay paddy soil (Oxisols) is a typical soil with low productivity in southern China. Nitrification inhibitors and slow release fertilizers have been used to improve nitrogen fertilizer utilization and reduce environmental impaction of the paddy soil. However, their effects on ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in paddy soil have rarely been investigated. In the present work, we compared the influences of several slow release fertilizers and nitrification inhibitors on the community structure and activities of the ammonia oxidizers in yellow clay soil. The abundances and community compositions of AOA and AOB were determined with qPCR, terminal restriction fragment length polymorphism (T-RFLP), and clone library approaches. Our results indicated that the potential nitrification rate (PNR) of the soil was significantly related to the abundances of both AOA and AOB. Nitrogen fertilizer application stimulated the growth of AOA and AOB, and the combinations of nitrapyrin with urea (NPU) and urea-formaldehyde (UF) inhibited the growth of AOA and AOB, respectively. Compared with other treatments, the applications of NPU and UF also led to significant shifts in the community compositions of AOA and AOB, respectively. NPU showed an inhibitory effect on AOA T-RF 166 bp that belonged to Nitrosotalea. UF had a negative effect on AOB T-RF 62 bp that was assigned to Nitrosospira. These results suggested that NPU inhibited PNR and increased nitrogen use efficiency (NUE) by inhibiting the growth of AOA and altering AOA community. UF showed no effect on NUE but decreased AOB abundance and shifted AOB community.

  8. Diversity and abundance of aerobic and anaerobic methane oxidizers at the Haakon Mosby Mud Volcano, Barents Sea.

    PubMed

    Lösekann, Tina; Knittel, Katrin; Nadalig, Thierry; Fuchs, Bernhard; Niemann, Helge; Boetius, Antje; Amann, Rudolf

    2007-05-01

    Submarine mud volcanoes are formed by expulsions of mud, fluids, and gases from deeply buried subsurface sources. They are highly reduced benthic habitats and often associated with intensive methane seepage. In this study, the microbial diversity and community structure in methane-rich sediments of the Haakon Mosby Mud Volcano (HMMV) were investigated by comparative sequence analysis of 16S rRNA genes and fluorescence in situ hybridization. In the active volcano center, which has a diameter of about 500 m, the main methane-consuming process was bacterial aerobic oxidation. In this zone, aerobic methanotrophs belonging to three bacterial clades closely affiliated with Methylobacter and Methylophaga species accounted for 56%+/-8% of total cells. In sediments below Beggiatoa mats encircling the center of the HMMV, methanotrophic archaea of the ANME-3 clade dominated the zone of anaerobic methane oxidation. ANME-3 archaea form cell aggregates mostly associated with sulfate-reducing bacteria of the Desulfobulbus (DBB) branch. These ANME-3/DBB aggregates were highly abundant and accounted for up to 94%+/-2% of total microbial biomass at 2 to 3 cm below the surface. ANME-3/DBB aggregates could be further enriched by flow cytometry to identify their phylogenetic relationships. At the outer rim of the mud volcano, the seafloor was colonized by tubeworms (Siboglinidae, formerly known as Pogonophora). Here, both aerobic and anaerobic methane oxidizers were found, however, in lower abundances. The level of microbial diversity at this site was higher than that at the central and Beggiatoa species-covered part of the HMMV. Analysis of methyl-coenzyme M-reductase alpha subunit (mcrA) genes showed a strong dominance of a novel lineage, mcrA group f, which could be assigned to ANME-3 archaea. Our results further support the hypothesis of Niemann et al. (54), that high methane availability and different fluid flow regimens at the HMMV provide distinct niches for aerobic and

  9. Diversity and Abundance of Aerobic and Anaerobic Methane Oxidizers at the Haakon Mosby Mud Volcano, Barents Sea▿

    PubMed Central

    Lösekann, Tina; Knittel, Katrin; Nadalig, Thierry; Fuchs, Bernhard; Niemann, Helge; Boetius, Antje; Amann, Rudolf

    2007-01-01

    Submarine mud volcanoes are formed by expulsions of mud, fluids, and gases from deeply buried subsurface sources. They are highly reduced benthic habitats and often associated with intensive methane seepage. In this study, the microbial diversity and community structure in methane-rich sediments of the Haakon Mosby Mud Volcano (HMMV) were investigated by comparative sequence analysis of 16S rRNA genes and fluorescence in situ hybridization. In the active volcano center, which has a diameter of about 500 m, the main methane-consuming process was bacterial aerobic oxidation. In this zone, aerobic methanotrophs belonging to three bacterial clades closely affiliated with Methylobacter and Methylophaga species accounted for 56% ± 8% of total cells. In sediments below Beggiatoa mats encircling the center of the HMMV, methanotrophic archaea of the ANME-3 clade dominated the zone of anaerobic methane oxidation. ANME-3 archaea form cell aggregates mostly associated with sulfate-reducing bacteria of the Desulfobulbus (DBB) branch. These ANME-3/DBB aggregates were highly abundant and accounted for up to 94% ± 2% of total microbial biomass at 2 to 3 cm below the surface. ANME-3/DBB aggregates could be further enriched by flow cytometry to identify their phylogenetic relationships. At the outer rim of the mud volcano, the seafloor was colonized by tubeworms (Siboglinidae, formerly known as Pogonophora). Here, both aerobic and anaerobic methane oxidizers were found, however, in lower abundances. The level of microbial diversity at this site was higher than that at the central and Beggiatoa species-covered part of the HMMV. Analysis of methyl-coenzyme M-reductase alpha subunit (mcrA) genes showed a strong dominance of a novel lineage, mcrA group f, which could be assigned to ANME-3 archaea. Our results further support the hypothesis of Niemann et al. (54), that high methane availability and different fluid flow regimens at the HMMV provide distinct niches for aerobic and

  10. Grassland management regimens reduce small-scale heterogeneity and species diversity of beta-proteobacterial ammonia pxidizer populations.

    PubMed

    Webster, Gordon; Embley, T Martin; Prosser, James I

    2002-01-01

    The impact of soil management practices on ammonia oxidizer diversity and spatial heterogeneity was determined in improved (addition of N fertilizer), unimproved (no additions), and semi-improved (intermediate management) grassland pastures at the Sourhope Research Station in Scotland. Ammonia oxidizer diversity within each grassland soil was assessed by PCR amplification of microbial community DNA with both ammonia oxidizer-specific, 16S rRNA gene (rDNA) and functional, amoA, gene primers. PCR products were analysed by denaturing gradient gel electrophoresis, phylogenetic analysis of partial 16S rDNA and amoA sequences, and hybridization with ammonia oxidizer-specific oligonucleotide probes. Ammonia oxidizer populations in unimproved soils were more diverse than those in improved soils and were dominated by organisms representing Nitrosospira clusters 1 and 3 and Nitrosomonas cluster 7 (closely related phylogenetically to Nitrosomonas europaea). Improved soils were only dominated by Nitrosospira cluster 3 and Nitrosomonas cluster 7. These differences were also reflected in functional gene (amoA) diversity, with amoA gene sequences of both Nitrosomonas and Nitrosospira species detected. Replicate 0.5-g samples of unimproved soil demonstrated significant spatial heterogeneity in 16S rDNA-defined ammonia oxidizer clusters, which was reflected in heterogeneity in ammonium concentration and pH. Heterogeneity in soil characteristics and ammonia oxidizer diversity were lower in improved soils. The results therefore demonstrate significant effects of soil management on diversity and heterogeneity of ammonia oxidizer populations that are related to similar changes in relevant soil characteristics.

  11. Distinct N2O yields of AOB and AOA driven ammonia oxidation across a range of Oregon forest soils

    NASA Astrophysics Data System (ADS)

    Tzanakakis, Vasileios; Dörsch, Peter; Taylor, Anne E.; Giguere, Andrew T.; Bakken, Lars R.; Bottomley, Peter J.; Myrold, David D.

    2017-04-01

    Ammonia oxidation, as the first and limiting step of nitrification, is a critical process in global N cycling and an important source of nitrous oxide (N2O). Previous studies reported strong contrasts in potential nitrification rates and niche separation of ammonia oxidizing bacteria (AOB) and archaea (AOA) in three acid Oregon forest soils depending on tree stands. In the present study we were interested in the potential contribution of AOB and AOA to nitrification-derived N2O in these soils. We performed soil slurry incubations amended with NH4+ and determined the specific N2O yields of AOB and AOA using inhibitor techniques. Despite large differences in edaphic factors, potential nitrification rates, and niche partitioning, AOB- and AOA-mediated nitrification displayed fairly stable and distinct N2O yields. The N2O yields ranged from 0.11 to 0.17% for AOB and from 0.03 to 0.08% for AOA, which is in agreement with findings of previous pure culture and soil studies. Nitrite accumulation was observed in only one soil, upon NH4+ stimulation of AOB growth, without showing any effect on the apparent N2O yield. The partitioning between AOB and AOA activity was strongly affected by soil pH and nitrogen status, but there was no effect of these variables on the group-specific N2O yield. Together, this suggests that N2O yields of different ammonia oxidizing microorganisms are under tight biochemical control and that the potential contribution of nitrification to N2O emission in acid forest soils can be predicted from AOB - AOA partitioning.

  12. Metabolic reprogramming during neuronal differentiation from aerobic glycolysis to neuronal oxidative phosphorylation

    PubMed Central

    Zheng, Xinde; Boyer, Leah; Jin, Mingji; Mertens, Jerome; Kim, Yongsung; Ma, Li; Ma, Li; Hamm, Michael; Gage, Fred H; Hunter, Tony

    2016-01-01

    How metabolism is reprogrammed during neuronal differentiation is unknown. We found that the loss of hexokinase (HK2) and lactate dehydrogenase (LDHA) expression, together with a switch in pyruvate kinase gene splicing from PKM2 to PKM1, marks the transition from aerobic glycolysis in neural progenitor cells (NPC) to neuronal oxidative phosphorylation. The protein levels of c-MYC and N-MYC, transcriptional activators of the HK2 and LDHA genes, decrease dramatically. Constitutive expression of HK2 and LDHA during differentiation leads to neuronal cell death, indicating that the shut-off aerobic glycolysis is essential for neuronal survival. The metabolic regulators PGC-1α and ERRγ increase significantly upon neuronal differentiation to sustain the transcription of metabolic and mitochondrial genes, whose levels are unchanged compared to NPCs, revealing distinct transcriptional regulation of metabolic genes in the proliferation and post-mitotic differentiation states. Mitochondrial mass increases proportionally with neuronal mass growth, indicating an unknown mechanism linking mitochondrial biogenesis to cell size. DOI: http://dx.doi.org/10.7554/eLife.13374.001 PMID:27282387

  13. The effect of long-term, high-volume aerobic exercise training on postprandial lipemia and oxidative stress.

    PubMed

    Bloomer, Richard J; Fisher-Wellman, Kelsey H; Bell, Heather K

    2010-04-01

    We have previously found no effect of moderate-volume aerobic exercise training (approximately 3 hrs*wk(-1)) on postprandial oxidative stress. It is possible that a higher volume of exercise is needed to impact postprandial oxidative stress in young, otherwise healthy individuals. Our purpose was to compare blood triglycerides (TAGs) and oxidative stress biomarkers in 10 healthy untrained and 10 healthy highly aerobically trained (eg, >or= 40 miles running*wk(-1) or >or= 150 miles cycling*wk(-1)) men and women following ingestion of a lipid meal. Blood samples were collected before (in a 10-hour fasted state), and 1, 2, 4, and 6 hours after ingestion of a lipid load (heavy whipping cream at 1 g*kg(-1)). Blood samples were analyzed for TAGs, malondialdehyde (MDA), hydrogen peroxide (H(2)O(2)), and nitrate/nitrite (NOx). No training status or interaction effects were noted for TAGs, MDA, H2O2, or NOx (P > 0.05). However, a time effect was noted for TAGs (P = 0.01), with values higher at 2 hours (67 +/- 6 mg*dL(-1)) compared with premeal (41 +/- 6 mg*dL(-1)). A time effect was also noted for H2O2 (P = 0.0001), with values higher at 2 hours (24 +/- 3 micromol*L(-1)), 4 hours (23 +/- 3 micromol*L(-1)), and 6 hours (21 +/- 3 mumol.L(-1)) compared with premeal (7 +/- 2 micromol*L(-1)). The time effect for MDA approached significance (P = 0.07), with values peaking at 4 hours post-meal (1.59 +/- 0.16 micromol*L(-1)) compared with premeal (0.99 +/- 0.15 micromol*L(-1)). These data indicate that aerobic exercise training (even when performed at a relatively high volume) does not attenuate postprandial lipemia or oxidative stress as compared with no exercise when healthy men and women consume a lipid load in the form of heavy whipping cream. Fasting TAG values may be most important in this regard. It is possible that long-term exercise may be capable of attenuating postprandial lipemia or oxidative stress in older individuals, those with chronic disease, or those with

  14. Links between Ammonia Oxidizer Community Structure, Abundance, and Nitrification Potential in Acidic Soils ▿ †

    PubMed Central

    Yao, Huaiying; Gao, Yangmei; Nicol, Graeme W.; Campbell, Colin D.; Prosser, James I.; Zhang, Limei; Han, Wenyan; Singh, Brajesh K.

    2011-01-01

    Ammonia oxidation is the first and rate-limiting step of nitrification and is performed by both ammonia-oxidizing archaea (AOA) and bacteria (AOB). However, the environmental drivers controlling the abundance, composition, and activity of AOA and AOB communities are not well characterized, and the relative importance of these two groups in soil nitrification is still debated. Chinese tea orchard soils provide an excellent system for investigating the long-term effects of low pH and nitrogen fertilization strategies. AOA and AOB abundance and community composition were therefore investigated in tea soils and adjacent pine forest soils, using quantitative PCR (qPCR), terminal restriction fragment length polymorphism (T-RFLP) and sequence analysis of respective ammonia monooxygenase (amoA) genes. There was strong evidence that soil pH was an important factor controlling AOB but not AOA abundance, and the ratio of AOA to AOB amoA gene abundance increased with decreasing soil pH in the tea orchard soils. In contrast, T-RFLP analysis suggested that soil pH was a key explanatory variable for both AOA and AOB community structure, but a significant relationship between community abundance and nitrification potential was observed only for AOA. High potential nitrification rates indicated that nitrification was mainly driven by AOA in these acidic soils. Dominant AOA amoA sequences in the highly acidic tea soils were all placed within a specific clade, and one AOA genotype appears to be well adapted to growth in highly acidic soils. Specific AOA and AOB populations dominated in soils at particular pH values and N content, suggesting adaptation to specific niches. PMID:21571885

  15. Aerobic exercise increases resistance to oxidative stress in sedentary older middle-aged adults. A pilot study.

    PubMed

    Done, Aaron J; Traustadóttir, Tinna

    2016-12-01

    Older individuals who exercise regularly exhibit greater resistance to oxidative stress than their sedentary peers, suggesting that exercise can modify age-associated loss of resistance to oxidative stress. However, we recently demonstrated that a single bout of exercise confers protection against a subsequent oxidative challenge in young, but not older adults. We therefore hypothesized that repeated bouts of exercise would be needed to increase resistance to an oxidative challenge in sedentary older middle-aged adults. Sedentary older middle-aged men and women (50-63 years, n = 11) participated in an 8-week exercise intervention. Maximal oxygen consumption was measured before and after the intervention. The exercise intervention consisted of three sessions per week, for 45 min at an intensity corresponding to 70-85 % maximal heart rate (HR max ). Resistance to oxidative stress was measured by F 2 -isoprostane response to a forearm ischemia/reperfusion (I/R) trial. Each participant underwent the I/R trial before and after the exercise intervention. The intervention elicited a significant increase in maximal oxygen consumption (VO 2max ) (P < 0.0001). Baseline levels of F 2 -isoprostanes pre- and post-intervention did not differ, but the F 2 -isoprostane response to the I/R trial was significantly lower following the exercise intervention (time-by-trial interaction, P = 0.043). Individual improvements in aerobic fitness were associated with greater improvements in the F 2 -isoprostane response (r = -0.761, P = 0.011), further supporting the role of aerobic fitness in resistance to oxidative stress. These data demonstrate that regular exercise with improved fitness leads to increased resistance to oxidative stress in older middle-aged adults and that this measure is modifiable in previously sedentary individuals.

  16. Calcium in the Mechanism of Ammonia-Induced Astrocyte Swelling

    PubMed Central

    Jayakumar, A.R.; Rao, K.V. Rama; Tong, X.Y; Norenberg, M.D.

    2016-01-01

    Brain edema, due largely to astrocyte swelling, is an important clinical problem in patients with acute liver failure. While mechanisms underlying astrocyte swelling in this condition are not fully understood, ammonia and associated oxidative/nitrosative stress (ONS) appear to be involved. Mechanisms responsible for the increase in reactive oxygen/nitrogen species (RONS) and their role in ammonia-induced astrocyte swelling, however, are poorly understood. Recent studies have demonstrated a transient increase in intracellular Ca2+ in cultured astrocytes exposed to ammonia. As Ca2+ is a known inducer of RONS, we investigated potential mechanisms by which Ca2+ may be responsible for the production of RONS and cell swelling in cultured astrocytes after treatment with ammonia. Exposure of cultured astrocytes to ammonia (5 mM) increased the formation of free radicals, including nitric oxide, and such increase was significantly diminished by treatment with the Ca2+ chelator BAPTA-AM. We then examined the activity of Ca2+-dependent enzymes that are known to generate RONS and found that ammonia significantly increased the activities of NADPH oxidase (NOX), constitutive nitric oxide synthase (cNOS) and phospholipase A2 (PLA2) and such increases in activity were significantly diminished by BAPTA. Pretreatment of cultures with 7-nitroindazole, apocyanin and quinacrine, respective inhibitors of cNOS, NOX and PLA2, all significantly diminished RONS production. Additionally, treatment of cultures with BAPTA or with inhibitors of cNOS, NOX and PLA2 reduced ammonia-induced astrocyte swelling. These studies suggest that the ammonia-induced rise in intracellular Ca2+ activates free radical producing enzymes that ultimately contribute to the mechanism of astrocyte swelling. PMID:19393035

  17. Acylated Ghrelin and Circulatory Oxidative Stress Markers Responses to Acute Resistance and Aerobic Exercise in Postmenopausal Women.

    PubMed

    Carteri, Randhall B; Lopes, André Luis; Schöler, Cinthia M; Correa, Cleiton Silva; Macedo, Rodrigo C; Gross, Júlia Silveira; Kruger, Renata Lopes; Homem de Bittencourt, Paulo I; Reischak-Oliveira, Álvaro

    2016-06-01

    Since exercise increases the production of reactive oxygen species in different tissues, the objective of this study is to evaluate, compare and correlate the acute effects of aerobic and resistance exercise in circulatory markers of oxidative stress and acylated ghrelin (AG) in postmenopausal women. Ten postmenopausal women completed different protocols: a control session (CON), an aerobic exercise session (AERO); and a single-set (SSR) or 3-set (MSR) resistance exercise protocol. After exercise, both MSR (P = .06) and AERO (P = .02) sessions showed significant increased lipid peroxidation compared with baseline levels. CON and SSR sessions showed no differences after exercise. No differences were found between sessions at any time for total glutathione, glutathione dissulfide or AG concentrations. Exercise significantly increased lipid peroxidation compared with baseline values. As pro oxidant stimuli is necessary to promote chronic adaptations to the antioxidant defenses induced by exercise, our findings are important to consider when evaluating exercise programs prescription variables aiming quality of life in this population.

  18. Atmospheric cycles of nitrogen oxides and ammonia. [source strengths and destruction rates

    NASA Technical Reports Server (NTRS)

    Bottger, A.; Ehhalt, D. H.; Gravenhorst, G.

    1981-01-01

    The atmospheric cycles of nitrogenous trace compounds for the Northern and Southern Hemispheres are discussed. Source strengths and destruction rates for the nitrogen oxides: NO, NO2 and HNO3 -(NOX) and ammonia (NH3) are given as a function of latitude over continents and oceans. The global amounts of NOX-N and NH3-N produced annually in the period 1950 to 1975 (34 + 5 x one trillion g NOx-N/yr and 29 + or - 6 x one trillion g NH3-N/yr) are much less than previously assumed. Globally, natural and anthropogenic emissions are of similar magnitude. The NOx emission from anthropogenic sources is 1.5 times that from natural processes in the Northern Hemisphere, whereas in the Southern Hemisphere, it is a factor of 3 or 4 less. More than 80% of atmospheric ammonia seems to be derived from excrements of domestic animals, mostly by bulk deposition: 24 + or - 9 x one trillion g NO3 -N/yr and 21 + or - 9 x one trillion g NH4+-N/yr. Another fraction may be removed by absorption on vegetation and soils.

  19. Interaction of Ammonia Monooxygenase from Nitrosomonas europaea with Alkanes, Alkenes, and Alkynes

    PubMed Central

    Hyman, Michael R.; Murton, Ian B.; Arp, Daniel J.

    1988-01-01

    Ammonia monooxygenase of Nitrosomonas europaea catalyzes the oxidation of alkanes (up to C8) to alcohols and alkenes (up to C5) to epoxides and alcohols in the presence of ammonium ions. Straight-chain, N-terminal alkynes (up to C10) all exhibited a time-dependent inhibition of ammonia oxidation without effects on hydrazine oxidation. PMID:16347810

  20. Ammonia-oxidizing bacterial community composition in estuarine and oceanic environments assessed using a functional gene microarray

    USGS Publications Warehouse

    Ward, B.B.; Eveillard, D.; Kirshtein, J.D.; Nelson, J.D.; Voytek, M.A.; Jackson, G.A.

    2007-01-01

    The relationship between environmental factors and functional gene diversity of ammonia-oxidizing bacteria (AOB) was investigated across a transect from the freshwater portions of the Chesapeake Bay and Choptank River out into the Sargasso Sea. Oligonucleotide probes (70-bp) designed to represent the diversity of ammonia monooxygenase (amoA) genes from Chesapeake Bay clone libraries and cultivated AOB were used to construct a glass slide microarray. Hybridization patterns among the probes in 14 samples along the transect showed clear variations in amoA community composition. Probes representing uncultivated members of the Nitrosospira-like AOB dominated the probe signal, especially in the more marine samples. Of the cultivated species, only Nitrosospira briensis was detected at appreciable levels. Discrimination analysis of hybridization signals detected two guilds. Guild 1 was dominated by the marine Nitrosospira-like probe signal, and Guild 2???s largest contribution was from upper bay (freshwater) sediment probes. Principal components analysis showed that Guild 1 was positively correlated with salinity, temperature and chlorophyll a concentration, while Guild 2 was positively correlated with concentrations of oxygen, dissolved organic carbon, and particulate nitrogen and carbon, suggesting that different amoA sequences represent organisms that occupy different ecological niches within the estuarine/marine environment. The trend from most diversity of AOB in the upper estuary towards dominance of a single type in the polyhaline region of the Bay is consistent with the declining importance of AOB with increasing salinity, and with the idea that AO-Archaea are the more important ammonia oxidizers in the ocean. ?? 2007 The Authors.

  1. Environmental factors shaping the community structure of ammonia-oxidizing bacteria and archaea in sugarcane field soil.

    PubMed

    Tago, Kanako; Okubo, Takashi; Shimomura, Yumi; Kikuchi, Yoshitomo; Hori, Tomoyuki; Nagayama, Atsushi; Hayatsu, Masahito

    2015-01-01

    The effects of environmental factors such as pH and nutrient content on the ecology of ammonia-oxidizing bacteria (AOB) and archaea (AOA) in soil has been extensively studied using experimental fields. However, how these environmental factors intricately influence the community structure of AOB and AOA in soil from farmers' fields is unclear. In the present study, the abundance and diversity of AOB and AOA in soils collected from farmers' sugarcane fields were investigated using quantitative PCR and barcoded pyrosequencing targeting the ammonia monooxygenase alpha subunit (amoA) gene. The abundances of AOB and AOA amoA genes were estimated to be in the range of 1.8 × 10(5)-9.2 × 10(6) and 1.7 × 10(6)-5.3 × 10(7) gene copies g dry soil(-1), respectively. The abundance of both AOB and AOA positively correlated with the potential nitrification rate. The dominant sequence reads of AOB and AOA were placed in Nitrosospira-related and Nitrososphaera-related clusters in all soils, respectively, which varied at the level of their sub-clusters in each soil. The relationship between these ammonia-oxidizing community structures and soil pH was shown to be significant by the Mantel test. The relative abundances of the OTU1 of Nitrosospira cluster 3 and Nitrososphaera subcluster 7.1 negatively correlated with soil pH. These results indicated that soil pH was the most important factor shaping the AOB and AOA community structures, and that certain subclusters of AOB and AOA adapted to and dominated the acidic soil of agricultural sugarcane fields.

  2. Environmental Factors Shaping the Community Structure of Ammonia-Oxidizing Bacteria and Archaea in Sugarcane Field Soil

    PubMed Central

    Tago, Kanako; Okubo, Takashi; Shimomura, Yumi; Kikuchi, Yoshitomo; Hori, Tomoyuki; Nagayama, Atsushi; Hayatsu, Masahito

    2015-01-01

    The effects of environmental factors such as pH and nutrient content on the ecology of ammonia-oxidizing bacteria (AOB) and archaea (AOA) in soil has been extensively studied using experimental fields. However, how these environmental factors intricately influence the community structure of AOB and AOA in soil from farmers’ fields is unclear. In the present study, the abundance and diversity of AOB and AOA in soils collected from farmers’ sugarcane fields were investigated using quantitative PCR and barcoded pyrosequencing targeting the ammonia monooxygenase alpha subunit (amoA) gene. The abundances of AOB and AOA amoA genes were estimated to be in the range of 1.8 × 105–9.2 × 106 and 1.7 × 106–5.3 × 107 gene copies g dry soil−1, respectively. The abundance of both AOB and AOA positively correlated with the potential nitrification rate. The dominant sequence reads of AOB and AOA were placed in Nitrosospira-related and Nitrososphaera-related clusters in all soils, respectively, which varied at the level of their sub-clusters in each soil. The relationship between these ammonia-oxidizing community structures and soil pH was shown to be significant by the Mantel test. The relative abundances of the OTU1 of Nitrosospira cluster 3 and Nitrososphaera subcluster 7.1 negatively correlated with soil pH. These results indicated that soil pH was the most important factor shaping the AOB and AOA community structures, and that certain subclusters of AOB and AOA adapted to and dominated the acidic soil of agricultural sugarcane fields. PMID:25736866

  3. Distinct responses in ammonia-oxidizing archaea and bacteria after addition of biosolids to an agricultural soil.

    PubMed

    Kelly, John J; Policht, Katherine; Grancharova, Tanya; Hundal, Lakhwinder S

    2011-09-01

    The recently discovered ammonia-oxidizing archaea (AOA) have been suggested as contributors to the first step of nitrification in terrestrial ecosystems, a role that was previously assigned exclusively to ammonia-oxidizing bacteria (AOB). The current study assessed the effects of agricultural management, specifically amendment of soil with biosolids or synthetic fertilizer, on nitrification rates and copy numbers of archaeal and bacterial ammonia monooxygenase (amoA) genes. Anaerobically digested biosolids or synthetic fertilizer was applied annually for three consecutive years to field plots used for corn production. Biosolids were applied at two loading rates, a typical agronomic rate (27 Mg hectare(-1) year(-1)) and double the agronomic rate (54 Mg hectare(-1) year(-1)), while synthetic fertilizer was applied at an agronomic rate typical for the region (291 kg N hectare(-1) year(-1)). Both biosolids amendments and synthetic fertilizer increased soil N and corn yield, but only the biosolids amendments resulted in significant increases in nitrification rates and increases in the copy numbers of archaeal and bacterial amoA genes. In addition, only archaeal amoA gene copy numbers increased in response to biosolids applied at the typical agronomic rate and showed a significant correlation with nitrification rates. Finally, copy numbers of archaeal amoA genes were significantly higher than copy numbers of bacterial amoA genes for all treatments. These results implicate AOA as being primarily responsible for the increased nitrification observed in an agricultural soil amended with biosolids. These results also support the hypothesis that physiological differences between AOA and AOB may enable them to occupy distinct ecological niches.

  4. High-Potential Electrocatalytic O2 Reduction with Nitroxyl / NOx Mediators: Implications for Fuel Cells and Aerobic Oxidation Catalysis

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gerken, James B.; Stahl, Shannon S.

    2015-07-15

    Efficient reduction of O2 to water is a central challenge in energy conversion and aerobic oxidation catalysis. In the present study, we investigate the electrochemical reduction of O2 with soluble organic nitroxyl and nitrogen oxide (NOx) mediators. When used alone, neither organic nitroxyls, such as TEMPO (2,2,6,6-tetramethyl-1-piperidinyl-N-oxyl), nor NOx species, such as sodium nitrite, are effective mediators of electrochemical O2 reduction. The combination of nitroxyl/NOx species, however, mediates sustained O2 reduction at electrochemical potentials of 0.19–0.33 V (vs. Fc/Fc+) in acetonitrile containing trifluoroacetic acid. Mechanistic analysis of the coupled redox reactions supports a process in which the nitrogen oxide catalystmore » drives aerobic oxidation of a nitroxyl mediator to an oxoammonium species, which then is reduced back to the nitroxyl at the cathode. The electrolysis potential is dictated by the oxoammonium/nitroxyl reduction potential. The high potentials observed with this ORR system benefit from the mechanism-based specificity for four-electron reduction of oxygen to water mediated by NOx species, together with kinetically efficient reduction of oxidized NOx species by TEMPO and other organic nitroxyls. This research was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center, funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences.« less

  5. Six weeks of aerobic dance exercise improves blood oxidative stress status and increases interleukin-2 in previously sedentary women.

    PubMed

    Leelarungrayub, Donrawee; Saidee, Kunteera; Pothongsunun, Prapas; Pratanaphon, Sainetee; YanKai, Araya; Bloomer, Richard J

    2011-07-01

    This study evaluated the change in blood oxidative stress, blood interleukin-2, and physical performance following 6 weeks of moderate intensity and duration aerobic dance exercise in 24 sedentary women. Blood samples were collected at rest twice before (baseline) and after the 6-week intervention for analysis of protein hydroperoxide (PrOOH), malondialdehyde (MDA), total anti-oxidant capacity (TAC), and interleukin-2 (IL-2) levels. Maximal treadmill run time (Time(max)) and maximal oxygen consumption (VO(2max)) were also measured. All variables were statistically analyzed with a repeated measurement ANOVA and Tukey post hoc. No differences were noted in any variable during the baseline period (p > 0.05). After aerobic dance exercise, VO(2max), Time(max), TAC and IL-2 were significantly increased, whereas MDA levels were decreased significantly (p < 0.05). PrOOH did not change either between baseline measures or after exercise. It can be concluded that aerobic dance exercise at a moderate intensity and duration can improve physical fitness, decrease MDA, and increase TAC and IL-2 in previously sedentary women. Copyright © 2010 Elsevier Ltd. All rights reserved.

  6. Phylogenetic diversity and ecological pattern of ammonia-oxidizing archaea in the surface sediments of the western Pacific.

    PubMed

    Cao, Huiluo; Hong, Yiguo; Li, Meng; Gu, Ji-Dong

    2011-11-01

    The phylogenetic diversity of ammonia-oxidizing archaea (AOA) was surveyed in the surface sediments from the northern part of the South China Sea (SCS). The distribution pattern of AOA in the western Pacific was discussed through comparing the SCS with other areas in the western Pacific including Changjiang Estuary and the adjacent East China Sea where high input of anthropogenic nitrogen was evident, the tropical West Pacific Continental Margins close to the Philippines, the deep-sea methane seep sediments in the Okhotsk Sea, the cold deep sea of Northeastern Japan Sea, and the hydrothermal field in the Southern Okinawa Trough. These various environments provide a wide spectrum of physical and chemical conditions for a better understanding of the distribution pattern and diversities of AOA in the western Pacific. Under these different conditions, the distinct community composition between shallow and deep-sea sediments was clearly delineated based on the UniFrac PCoA and Jackknife Environmental Cluster analyses. Phylogenetic analyses showed that a few ammonia-oxidizing archaeal subclades in the marine water column/sediment clade and endemic lineages were indicative phylotypes for some environments. Higher phylogenetic diversity was observed in the Philippines while lower diversity in the hydrothermal vent habitat. Water depth and possibly with other environmental factors could be the main driving forces to shape the phylogenetic diversity of AOA observed, not only in the SCS but also in the whole western Pacific. The multivariate regression tree analysis also supported this observation consistently. Moreover, the functions of current and other climate factors were also discussed in comparison of phylogenetic diversity. The information collectively provides important insights into the ecophysiological requirements of uncultured ammonia-oxidizing archaeal lineages in the western Pacific Ocean.

  7. Substrate availability drives spatial patterns in richness of ammonia-oxidizing bacteria and archaea in temperate forest soils

    Treesearch

    J.S. Norman; J.E. Barrett

    2016-01-01

    We sought to investigate the drivers of richness of ammonia-oxidizing bacteria (AOB) and archaea (AOA) in temperate forest soils. We sampled soils across four experimental watersheds in the Coweeta Hydrologic Laboratory, North Carolina USA. These watersheds are geographically close, but vary in soil chemistry due to differences in land use history. While we...

  8. Archaea Dominate the Ammonia-Oxidizing Community in Deep-Sea Sediments of the Eastern Indian Ocean—from the Equator to the Bay of Bengal

    PubMed Central

    Wang, Jing; Kan, Jinjun; Zhang, Xiaodong; Xia, Zhiqiang; Zhang, Xuecheng; Qian, Gang; Miao, Yanyi; Leng, Xiaoyun; Sun, Jun

    2017-01-01

    Ammonia-oxidizing Archaea (AOA) and ammonia-oxidizing Bacteria (AOB) oxidize ammonia to nitrite, and therefore play essential roles in nitrification and global nitrogen cycling. To better understand the population structure and the distribution of AOA and AOB in the deep Eastern Indian Ocean (EIO), nine surface sediment samples (>3,300 m depth) were collected during the inter-monsoon Spring 2013. One sediment sample from the South China Sea (SCS; 2,510 m) was also included for comparison. The community composition, species richness, and diversity were characterized by clone libraries (total 1,238 clones), and higher diversity of archaeal amoA genes than bacterial amoA genes was observed in all analyzed samples. Real time qPCR analysis also demonstrated higher abundances (gene copy numbers) of archaeal amoA genes than bacterial amoA genes, and the ratios of AOA/AOB ranged from 1.42 to 8.49 among sites. In addition, unique and distinct clades were found in both reconstructed AOA and AOB phylogeny, suggesting the presence of niche-specific ammonia-oxidizing microorganisms in the EIO. The distribution pattern of both archaeal and bacterial amoA genes revealed by NMDS (non-metric multidimensional scaling) showed a distinct geographic separation of the sample from the SCS and most of the samples from the EIO following nitrogen gradients. Higher abundance and diversity of archaeal amoA genes indicated that AOA may play a more important role than AOB in the deep Indian Ocean. Environmental parameters shaping the distribution pattern of AOA were different from that of AOB, indicating distinct metabolic characteristics and/or adaptation mechanisms between AOA and AOB in the EIO, especially in deep-sea environments. PMID:28360898

  9. Impact of hazardous events on the removal of nutrients and trace organic contaminants by an anoxic-aerobic membrane bioreactor receiving real wastewater.

    PubMed

    Phan, Hop V; Hai, Faisal I; McDonald, James A; Khan, Stuart J; van de Merwe, Jason P; Leusch, Frederic D L; Zhang, Ren; Price, William E; Broeckmann, Andreas; Nghiem, Long D

    2015-09-01

    The impacts of four simulated hazardous events, namely, aeration failure, power loss, and chemical shocks (ammonia or bleach) on the performance of an anoxic-aerobic membrane bioreactor (MBR) receiving real wastewater were investigated. Hazardous events could alter pH and/or oxidation reduction potential of the mixed liquor and inhibit biomass growth, thus affecting the removal of bulk organics, nutrients and trace organic contaminants (TrOC). Chemical shocks generally exerted greater impact on MBR performance than aeration/power failure events, with ammonia shock exerting the greatest impact. Compared to total organic carbon, nutrient removal was more severely affected. Removal of the hydrophilic TrOCs that are resistant and/or occur at high concentrations in wastewater was notably affected. The MBR effectively reduced estrogenicity and toxicity from wastewater, but chemical shocks could temporarily increase the endocrine activity of the effluent. Depending on the chemical shock-dose and the membrane flux, hazardous events can exacerbate membrane fouling. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Eosin Y-catalyzed visible-light-mediated aerobic oxidative cyclization of N,N-dimethylanilines with maleimides.

    PubMed

    Liang, Zhongwei; Xu, Song; Tian, Wenyan; Zhang, Ronghua

    2015-01-01

    A novel and simple strategy for the efficient synthesis of the corresponding tetrahydroquinolines from N,N-dimethylanilines and maleimides using visible light in an air atmosphere in the presence of Eosin Y as a photocatalyst has been developed. The metal-free protocol involves aerobic oxidative cyclization via sp(3) C-H bond functionalization process to afford good yields in a one-pot procedure under mild conditions.

  11. Ammonia gas sensors based on chemically reduced graphene oxide sheets self-assembled on Au electrodes

    PubMed Central

    2014-01-01

    We present a useful ammonia gas sensor based on chemically reduced graphene oxide (rGO) sheets by self-assembly technique to create conductive networks between parallel Au electrodes. Negative graphene oxide (GO) sheets with large sizes (>10 μm) can be easily electrostatically attracted onto positive Au electrodes modified with cysteamine hydrochloride in aqueous solution. The assembled GO sheets on Au electrodes can be directly reduced into rGO sheets by hydrazine or pyrrole vapor and consequently provide the sensing devices based on self-assembled rGO sheets. Preliminary results, which have been presented on the detection of ammonia (NH3) gas using this facile and scalable fabrication method for practical devices, suggest that pyrrole-vapor-reduced rGO exhibits much better (more than 2.7 times with the concentration of NH3 at 50 ppm) response to NH3 than that of rGO reduced from hydrazine vapor. Furthermore, this novel gas sensor based on rGO reduced from pyrrole shows excellent responsive repeatability to NH3. Overall, the facile electrostatic self-assembly technique in aqueous solution facilitates device fabrication, the resultant self-assembled rGO-based sensing devices, with miniature, low-cost portable characteristics and outstanding sensing performances, which can ensure potential application in gas sensing fields. PMID:24917701

  12. Numerical analysis on effect of aspect ratio of planar solid oxide fuel cell fueled with decomposed ammonia

    NASA Astrophysics Data System (ADS)

    Tan, Wee Choon; Iwai, Hiroshi; Kishimoto, Masashi; Brus, Grzegorz; Szmyd, Janusz S.; Yoshida, Hideo

    2018-04-01

    Planar solid oxide fuel cells (SOFCs) with decomposed ammonia are numerically studied to investigate the effect of the cell aspect ratio. The ammonia decomposer is assumed to be located next to the SOFCs, and the heat required for the endothermic decomposition reaction is supplied by the thermal radiation from the SOFCs. Cells with aspect ratios (ratios of the streamwise length to the spanwise width) between 0.130 and 7.68 are provided with the reactants at a constant mass flow rate. A parametric study is conducted by varying the cell temperature and fuel utility factor to investigate their effects on the cell performance in terms of the voltage efficiency. The effect of the heat supply to the ammonia decomposer is also studied. The developed model shows good agreement, in terms of the current-voltage curve, with the experimental data obtained from a short stack without parameter tuning. The simulation study reveals that the cell with the highest aspect ratio achieves the highest performance under furnace operation. On the other hand, the 0.750 aspect ratio cell with the highest voltage efficiency of 0.67 is capable of thermally sustaining the ammonia decomposers at a fuel utility of 0.80 using the thermal radiation from both sidewalls.

  13. Isolated and combined exposure to ammonia and nitrite in giant freshwater pawn (Macrobrachium rosenbergii): effects on the oxidative stress, antioxidant enzymatic activities and apoptosis in haemocytes.

    PubMed

    Zhang, Yufan; Ye, Chaoxia; Wang, Anli; Zhu, Xuan; Chen, Changhong; Xian, Jianan; Sun, Zhenzhu

    2015-10-01

    The residual contaminators such as ammonia and nitrite are widely considered as relevant sources of aquatic environmental pollutants, posing a great threat to shrimp survival. To study the toxicological effects of ammonia and nitrite exposure on the innate immune response in invertebrates, we investigated the oxidative stress and apoptosis in haemocytes of freshwater prawn (Macrobrachium rosenbergii) under isolated and combined exposure to ammonia and nitrite in order to provide useful information about adult prawn immune responses. M. rosenbergii (13.44 ± 2.75 g) were exposed to 0, 5, and 25 mg/L total ammonia-N (TAN) and 0, 5, and 20 mg/L nitrite-N for 24 h. All ammonia concentrations were combined with all nitrite concentrations, making a total of nine treatments studied. Following the exposure treatment, antioxidant enzyme activity, reactive oxygen species (ROS) generation, nitric oxide (NO) generation, and apoptotic cell ratio of haemocytes were measured using flow cytometry. Results indicated that ROS generation was sensitive to the combined effect of ammonia and nitrite, which subsequently affected the Cu-Zn SOD activity. In addition, CAT showed the highest activity at 5 mg/L TAN while GPx decreased at 5 mg/L TAN and returned towards baseline at 25 mg/L. NO generation synchronized with the apoptotic cell ratio in haemocytes, indicating that NO production was closely associated with programmed cell death. Both NO production and apoptotic ratios significantly decreased following 25 mg/L TAN, which may be due to the antagonistic regulation of NO and GPx. We hypothesized that the toxicological effect of nitrite exhibited less change in physiological changes compared to that of ammonia, because of the high tolerance to nitrite exposure in mature M. rosenbergii and/or the competitive effects of chloride ions. Taken together, these results showed that ammonia and nitrite caused a series of combined oxidative stress and apoptosis in M. rosenbergi, but further

  14. Ammonia exposure induces oxidative stress, endoplasmic reticulum stress and apoptosis in hepatopancreas of pacific white shrimp (Litopenaeus vannamei).

    PubMed

    Liang, Zhongxiu; Liu, Rui; Zhao, Depeng; Wang, Lingling; Sun, Mingzhe; Wang, Mengqiang; Song, Linsheng

    2016-07-01

    Ammonia is one of major environmental pollutants in the aquatic system that poses a great threat to the survival of shrimp. In the present study, the mRNA expression of endoplasmic reticulum (ER) stress marker and unfolded protein response (UPR) related genes, as well as the change of redox enzyme and apoptosis were investigated in hepatopancreas of the pacific white shrimp, Litopenaeus vannamei after the exposure of 20 mg L(-1) total ammonia nitrogen (TAN). Compared with the control group, the superoxide dismutase (SOD) activity in hepatopancreas decreased significantly (p < 0.05) at 96 h, whereas the malonyldialdehyde (MDA) concentration increased significantly (p < 0.05). The mRNA expression levels of ER stress marker-immunoglobulin heavy chain binding protein (Bip) gene and key UPR related genes including activating transcription factor 4 (ATF4) and the spliced form of X box binding protein 1 (XBP1) increased significantly (p < 0.05) in hepatopancreas at 96 h after exposure to ammonia. In addition, apoptosis was observed obviously in the hepatopancreas of L. vannamei after exposure to ammonia by the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay. The results indicated that ammonia exposure could induce oxidative stress, which further caused ER stress and apoptosis in hepatopancreas of L. vannamei. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. A template-free solvent-mediated synthesis of high surface area boron nitride nanosheets for aerobic oxidative desulfurization.

    PubMed

    Wu, Peiwen; Zhu, Wenshuai; Chao, Yanhong; Zhang, Jinshui; Zhang, Pengfei; Zhu, Huiyuan; Li, Changfeng; Chen, Zhigang; Li, Huaming; Dai, Sheng

    2016-01-04

    Hexagonal boron nitride nanosheets (h-BNNs) with rather high specific surface area (SSA) are important two-dimensional layer-structured materials. Here, a solvent-mediated synthesis of h-BNNs revealed a template-free lattice plane control strategy that induced high SSA nanoporous structured h-BNNs with outstanding aerobic oxidative desulfurization performance.

  16. Ammonia oxidizers and nitrite-oxidizing bacteria respond differently to long-term manure application in four paddy soils of south of China.

    PubMed

    Liu, Haiyang; Li, Jia; Zhao, Yan; Xie, Kexin; Tang, Xianjin; Wang, Shaoxian; Li, Zhongpei; Liao, Yulin; Xu, Jianming; Di, Hongjie; Li, Yong

    2018-08-15

    Nitrification plays an important role in the soil nitrogen (N) cycle, and fertilizer application may influence soil nitrifiers' abundance and composition. However, the effect of long-term manure application in paddy soils on nitrifying populations is poorly understood. We chose four long-term manure experimental fields in the south of China to study how the abundance and community structure of nitrifiers would change in response to long-term manure application using quantitative PCR and Miseq sequencing analyses. Our results showed that manure application significantly increased ammonia oxidizing archaea (AOA) abundance at the ChangSha (CS) and NanChang (NC) sites, while the abundance of ammonia oxidizing bacteria (AOB) represented 4.8- and 12.8- fold increases at the JiaXing (JX) and YingTan (YT) sites, respectively. Miseq sequencing of 16S rRNA genes indicated that manure application altered the community structure of nitrifying populations, especially at the NC and YT sites. The application of manure significantly changed AOA and nitrite oxidizing bacteria (NOB) community structures but not those of AOB, suggesting that AOA and NOB may be more sensitive to manures. Variation partitioning analysis (VPA) and redundancy analysis (RDA) indicated that soil pH, TN, NO 3 - -N and water content were the main factors in shaping nitrifying communities. These findings suggest that nitrifiers respond diversely to manure application, and soil physiochemical properties play an important role in determining nitrifiers' abundance and communities with long-term manure addition. Copyright © 2018 Elsevier B.V. All rights reserved.

  17. Effect of chromium (VI) on the multiple nitrogen removal pathways and microbial community of aerobic granular sludge.

    PubMed

    Zheng, Xiao-Ying; Lu, Dan; Wang, Ming-Yang; Chen, Wei; Zhou, Gan; Zhang, Yuan

    2017-06-12

    The frequent appearance of Cr(VI) significantly impacts the microbial metabolism in wastewater. In this study, long-term effects of Cr(VI) on microbial community, nitrogen removal pathways and mechanism of aerobic granular sludge (AGS) were investigated. AGS had strong resistance ability to 1.0 mg/L Cr(VI). 3.0 mg/L Cr(VI) increased the heterotrophic-specific ammonia uptake rate (HSAUR) and heterotrophic-specific nitrate uptake rate (HSNUR) transiently, whereas 5.0 mg/L Cr(VI) sharply decreased the specific ammonia uptake rate (SAUR), specific nitrate uptake rate (SNUR) and simultaneous nitrification denitrification rate (SNDR). It was found that Cr (VI) has a greater inhibitory effect on autotrophic nitrification (ASAUR), and the maximal inhibition rate (IR) was 139.19%. Besides, the inhibition of Cr (VI) on nitrogen removal process belongs to non-competitive inhibition. Cr(VI) had a weaker negative impact on heterotrophic bacteria compared with that on autotrophic bacteria. Denaturing gradient gel electrophoresis analyses suggest that Acidovorax sp., flavobacterium sp., uncultured soil bacterium, uncultured nitrosospira sp., uncultured prokaryote, uncultured β-proteobacterium and uncultured pseudomonas sp. were the dominant species. The inhibition of Cr(VI) on nitrite-oxidizing bacteria was the strongest, followed by ammonia-oxidizing bacteria and denitrifying bacteria. Linear correlations between bacterial count and biomass-specific uptake rate were observed when the Cr(VI) concentration exceeded 3 mg/L. This study revealed the effect of Cr(VI) on nitrification is more serious than that on denitrification. Autotrophic and heterotrophic nitrification, heterotrophic denitrification and simultaneous nitrification denitrification played a significant role on nitrogen removal under Cr(VI) stress.

  18. Pd-catalyzed aerobic oxidative annulation of cyclohexanones and 2-aminophenyl ketones: A direct approach to acridines

    NASA Astrophysics Data System (ADS)

    Mu, Wanlu; Li, Xiaowei; Wang, Longfei; Chen, Yong; Wu, Yanchao

    2017-08-01

    An efficient aerobic oxidative annulation of cyclohexanones and 2-aminophenyl ketones approach to substituted acridines, a structural motif for a large number of pharmaceuticals and functional materials is described. The key feature of this method is the use of oxygen as the sole oxidant and Pd catalyst, which resulting in the high regioselectivity with unsymmetrical meta-substituted cyclohexanones. The electron gap of the global redox condensation process is filled and the reaction efficiency is significantly promoted by O2 as a redox moderator. This protocol possesses many advantages such as using O2 as a cheap and nonhazardous oxidant, high regioselectivity and water as the only by-product, which meet the principle of green chemistry.

  19. Enrichment of Thermophilic Ammonia-Oxidizing Archaea from an Alkaline Hot Spring in the Great Basin, USA

    NASA Astrophysics Data System (ADS)

    Zhang, C.; Huang, Z.; Jiang, H.; Wiegel, J.; Li, W.; Dong, H.

    2010-12-01

    One of the major advances in the nitrogen cycle is the recent discovery of ammonia oxidation by archaea. While culture-independent studies have revealed occurrence of ammonia-oxidizing archaea (AOA) in nearly every surface niche on earth, most of these microorganisms have resisted isolation and so far only a few species have been identified. The Great Basin contains numerous hot springs, which are characterized by moderately high temperature (40-65 degree C) and circumneutral or alkaline pH. Unique thermophilic archaea have been identified based on molecular DNA and lipid biomarkers; some of which may be ammonia oxidizers. This study aims to isolate some of these archaea from a California hot spring that has pH around 9.0 and temperature around 42 degree C. Mat material was collected from the spring and transported on ice to the laboratory. A synthetic medium (SCM-5) was inoculated with the mat material and the culture was incubated under varying temperature (35-65 degree C) and pH (7.0-10.0) conditions using antibiotics to suppress bacterial growth. Growth of the culture was monitored by microscopy, decrease in ammonium and increase in nitrite, and increases in Crenarchaeota and AOA abundances over time. Clone libraries were constructed to compare archaeal community structures before and after the enrichment experiment. Temperature and pH profiles indicated that the culture grew optimally at pH 9.0 and temperature 45 degree C, which are consistent with the geochemical conditions of the natural environment. Phylogenetic analysis showed that the final OTU was distantly related to all known hyperthermophilic archaea. Analysis of the amoA genes showed two OTUs in the final culture; one of them was closely related to Candidatus Nitrososphaera gargensis. However, the enrichment culture always contained bacteria and attempts to separate them from archaea have failed. This highlights the difficulty in bringing AOA into pure culture and suggests that some of the AOA may

  20. NFκB in the Mechanism of Ammonia-Induced Astrocyte Swelling in Culture

    PubMed Central

    Sinke, A.P.; Jayakumar, A.R.; Panickar, K.S.; Moriyama, M.; Reddy, P.V.B.; Norenberg, M.D.

    2008-01-01

    Astrocyte swelling and brain edema are major neuropathological findings in the acute form of hepatic encephalopathy (fulminant hepatic failure, FHF), and substantial evidence supports the view that elevated brain ammonia level is an important etiological factor in this condition. Although the mechanism by which ammonia brings about astrocyte swelling remains to be determined, oxidative/nitrosative stress and mitogen-activated protein kinases (MAPKs) have been considered as important elements in this process. One factor known to be activated by both oxidative stress and MAPKs is nuclear factor κB (NFκB), a transcription factor that activates many genes, including inducible nitric oxide synthase (iNOS). Since the product of iNOS, nitric oxide (NO), is known to cause astrocyte swelling, we examined the potential involvement of NFκB in ammonia-induced astrocyte swelling. Western blot analysis of cultured astrocytes showed a significant increase in NFκB nuclear translocation (a measure of NFκB activation) from 12 h to 2 days after treatment with NH4Cl (5 mM). Cultures treated with antioxidants, including superoxide dismutase, catalase and vitamin E, as well as the MAPKs inhibitors SB239063 (an inhibitor of p38-MAPK), and SP600125 (an inhibitor of c-Jun N-terminal kinase, JNK) significantly diminished NFκB activation by ammonia, supporting a role of oxidative stress and MAPKs in NFκB activation. The activation of NFκB was associated with increased iNOS protein expression and NO generation, and these changes were blocked by BAY 11-7082, an inhibitor of NFκB. Additionally, ammonia-induced astrocyte swelling was inhibited by the NFκB inhibitors BAY 11-7082 and SN-50, thereby implicating NFκB in the mechanism of astrocyte swelling. Our studies indicate that cultured astrocytes exposed to ammonia display NFκB activation, which is likely a consequence of oxidative stress and activation of MAPKs. NFκB activation appears to contribute to the mechanism of ammonia

  1. A template-free solvent-mediated synthesis of high surface area boron nitride nanosheets for aerobic oxidative desulfurization

    DOE PAGES

    Wu, Peiwen; Zhu, Wenshuai; Chao, Yanhong; ...

    2015-10-16

    Hexagonal boron nitride nanosheets (h-BNNs) with rather high specific surface area (SSA) are important two-dimensional layer-structured materials. Here in this study, a solvent-mediated synthesis of h-BNNs revealed a template-free lattice plane control strategy that induced high SSA nanoporous structured h-BNNs with outstanding aerobic oxidative desulfurization performance.

  2. High pH ammonia toxicity, and the search for life on the Jovian planets.

    PubMed

    Deal, P H; Souza, K A; Mack, H M

    1975-10-01

    Jovian plants have enviroments apparently suitable for the evolution of life, but nevertheless, present severe challenges to organisms. One such challenge arises from the presence of ammonia. Ammonia is an efficient biocide, its effect being dependent on pH as well as on concentration. The effects of pH and ammonia concentration were studied separately, where possible, on a variety of organisms, including some isolated from natural enviornments of high pH and/or ammonia concentration. Escherichia coli and Bacillus subtilis are both extremely sensitive to ammonia. An aerobic organism (growth up to pH 11.4) from an alkaline spring is more resistant, but exhibits a toxic response to ammonia at a pH much lower than its maximum for growth. The greatest ammonia resistance has been found in an unidentified organism growing at near neutral pH. Even in this case, however, survival at ammonia concentrations reasonably expected on the Jovian planets is measured in hours. This is, nevertheless, two to three orders of magnitude longer than for E. coli. Our data support the tentative conclusion that contamination of the Jovian planets with terrestrial organisms that can grow is unlikely. However, the range of toxic response noted, coupled with the observation that terrestrial life has not been exposed to high ammonia concentrations for millions of years, suggests that adaptation to greater ammonia tolerance may be possible.

  3. Practical Synthesis of Amides via Copper/ABNO-Catalyzed Aerobic Oxidative Coupling of Alcohols and Amines.

    PubMed

    Zultanski, Susan L; Zhao, Jingyi; Stahl, Shannon S

    2016-05-25

    A modular Cu/ABNO catalyst system has been identified that enables efficient aerobic oxidative coupling of alcohols and amines to amides. All four permutations of benzylic/aliphatic alcohols and primary/secondary amines are viable in this reaction, enabling broad access to secondary and tertiary amides. The reactions exhibit excellent functional group compatibility and are complete within 30 min-3 h at rt. All components of the catalyst system are commercially available.

  4. Aerobic capacity and hepatic mitochondrial lipid oxidation alters susceptibility for chronic high-fat diet-induced hepatic steatosis.

    PubMed

    Morris, E Matthew; Meers, Grace M E; Koch, Lauren G; Britton, Steven L; Fletcher, Justin A; Fu, Xiaorong; Shankar, Kartik; Burgess, Shawn C; Ibdah, Jamal A; Rector, R Scott; Thyfault, John P

    2016-10-01

    Rats selectively bred for high capacity running (HCR) or low capacity running (LCR) display divergence for intrinsic aerobic capacity and hepatic mitochondrial oxidative capacity, both factors associated with susceptibility for nonalcoholic fatty liver disease. Here, we tested if HCR and LCR rats display differences in susceptibility for hepatic steatosis after 16 wk of high-fat diets (HFD) with either 45% or 60% of kcals from fat. HCR rats were protected against HFD-induced hepatic steatosis, whereas only the 60% HFD induced steatosis in LCR rats, as marked by a doubling of liver triglycerides. Hepatic complete fatty acid oxidation (FAO) and mitochondrial respiratory capacity were all lower in LCR compared with HCR rats. LCR rats also displayed lower hepatic complete and incomplete FAO in the presence of etomoxir, suggesting a reduced role for noncarnitine palmitoyltransferase-1-mediated lipid catabolism in LCR versus HCR rats. Hepatic complete FAO and mitochondrial respiration were largely unaffected by either chronic HFD; however, 60% HFD feeding markedly reduced 2-pyruvate oxidation, a marker of tricarboxylic acid (TCA) cycle flux, and mitochondrial complete FAO only in LCR rats. LCR rats displayed lower levels of hepatic long-chain acylcarnitines than HCR rats but maintained similar levels of hepatic acetyl-carnitine levels, further supporting lower rates of β-oxidation, and TCA cycle flux in LCR than HCR rats. Finally, only LCR rats displayed early reductions in TCA cycle genes after the acute initiation of a HFD. In conclusion, intrinsically high aerobic capacity confers protection against HFD-induced hepatic steatosis through elevated hepatic mitochondrial oxidative capacity.

  5. Aerobic capacity and hepatic mitochondrial lipid oxidation alters susceptibility for chronic high-fat diet-induced hepatic steatosis

    PubMed Central

    Morris, E. Matthew; Meers, Grace M. E.; Koch, Lauren G.; Britton, Steven L.; Fletcher, Justin A.; Fu, Xiaorong; Shankar, Kartik; Burgess, Shawn C.; Ibdah, Jamal A.; Rector, R. Scott

    2016-01-01

    Rats selectively bred for high capacity running (HCR) or low capacity running (LCR) display divergence for intrinsic aerobic capacity and hepatic mitochondrial oxidative capacity, both factors associated with susceptibility for nonalcoholic fatty liver disease. Here, we tested if HCR and LCR rats display differences in susceptibility for hepatic steatosis after 16 wk of high-fat diets (HFD) with either 45% or 60% of kcals from fat. HCR rats were protected against HFD-induced hepatic steatosis, whereas only the 60% HFD induced steatosis in LCR rats, as marked by a doubling of liver triglycerides. Hepatic complete fatty acid oxidation (FAO) and mitochondrial respiratory capacity were all lower in LCR compared with HCR rats. LCR rats also displayed lower hepatic complete and incomplete FAO in the presence of etomoxir, suggesting a reduced role for noncarnitine palmitoyltransferase-1-mediated lipid catabolism in LCR versus HCR rats. Hepatic complete FAO and mitochondrial respiration were largely unaffected by either chronic HFD; however, 60% HFD feeding markedly reduced 2-pyruvate oxidation, a marker of tricarboxylic acid (TCA) cycle flux, and mitochondrial complete FAO only in LCR rats. LCR rats displayed lower levels of hepatic long-chain acylcarnitines than HCR rats but maintained similar levels of hepatic acetyl-carnitine levels, further supporting lower rates of β-oxidation, and TCA cycle flux in LCR than HCR rats. Finally, only LCR rats displayed early reductions in TCA cycle genes after the acute initiation of a HFD. In conclusion, intrinsically high aerobic capacity confers protection against HFD-induced hepatic steatosis through elevated hepatic mitochondrial oxidative capacity. PMID:27600823

  6. Low-Dissolved-Oxygen Nitrifying Systems Exploit Ammonia-Oxidizing Bacteria with Unusually High Yields▿

    PubMed Central

    Bellucci, Micol; Ofiţeru, Irina D.; Graham, David W.; Head, Ian M.; Curtis, Thomas P.

    2011-01-01

    In wastewater treatment plants, nitrifying systems are usually operated with elevated levels of aeration to avoid nitrification failures. This approach contributes significantly to operational costs and the carbon footprint of nitrifying wastewater treatment processes. In this study, we tested the effect of aeration rate on nitrification by correlating ammonia oxidation rates with the structure of the ammonia-oxidizing bacterial (AOB) community and AOB abundance in four parallel continuous-flow reactors operated for 43 days. Two of the reactors were supplied with a constant airflow rate of 0.1 liter/min, while in the other two units the airflow rate was fixed at 4 liters/min. Complete nitrification was achieved in all configurations, though the dissolved oxygen (DO) concentration was only 0.5 ± 0.3 mg/liter in the low-aeration units. The data suggest that efficient performance in the low-DO units resulted from elevated AOB levels in the reactors and/or putative development of a mixotrophic AOB community. Denaturing gel electrophoresis and cloning of AOB 16S rRNA gene fragments followed by sequencing revealed that the AOB community in the low-DO systems was a subset of the community in the high-DO systems. However, in both configurations the dominant species belonged to the Nitrosomonas oligotropha lineage. Overall, the results demonstrated that complete nitrification can be achieved at low aeration in lab-scale reactors. If these findings could be extended to full-scale plants, it would be possible to minimize the operational costs and greenhouse gas emissions without risk of nitrification failure. PMID:21926211

  7. Differential contributions of archaeal ammonia oxidizer ecotypes to nitrification in coastal surface waters

    PubMed Central

    Smith, Jason M; Casciotti, Karen L; Chavez, Francisco P; Francis, Christopher A

    2014-01-01

    The occurrence of nitrification in the oceanic water column has implications extending from local effects on the structure and activity of phytoplankton communities to broader impacts on the speciation of nitrogenous nutrients and production of nitrous oxide. The ammonia-oxidizing archaea, responsible for carrying out the majority of nitrification in the sea, are present in the marine water column as two taxonomically distinct groups. Water column group A (WCA) organisms are detected at all depths, whereas Water column group B (WCB) are present primarily below the photic zone. An open question in marine biogeochemistry is whether the taxonomic definition of WCA and WCB organisms and their observed distributions correspond to distinct ecological and biogeochemical niches. We used the natural gradients in physicochemical and biological properties that upwelling establishes in surface waters to study their roles in nitrification, and how their activity—ascertained from quantification of ecotype-specific ammonia monooxygenase (amoA) genes and transcripts—varies in response to environmental fluctuations. Our results indicate a role for both ecotypes in nitrification in Monterey Bay surface waters. However, their respective contributions vary, due to their different sensitivities to surface water conditions. WCA organisms exhibited a remarkably consistent level of activity and their contribution to nitrification appears to be related to community size. WCB activity was less consistent and primarily constrained to colder, high nutrient and low chlorophyll waters. Overall, the results of our characterization yielded a strong, potentially predictive, relationship between archaeal amoA gene abundance and the rate of nitrification. PMID:24553472

  8. Distinct Responses in Ammonia-Oxidizing Archaea and Bacteria after Addition of Biosolids to an Agricultural Soil▿

    PubMed Central

    Kelly, John J.; Policht, Katherine; Grancharova, Tanya; Hundal, Lakhwinder S.

    2011-01-01

    The recently discovered ammonia-oxidizing archaea (AOA) have been suggested as contributors to the first step of nitrification in terrestrial ecosystems, a role that was previously assigned exclusively to ammonia-oxidizing bacteria (AOB). The current study assessed the effects of agricultural management, specifically amendment of soil with biosolids or synthetic fertilizer, on nitrification rates and copy numbers of archaeal and bacterial ammonia monooxygenase (amoA) genes. Anaerobically digested biosolids or synthetic fertilizer was applied annually for three consecutive years to field plots used for corn production. Biosolids were applied at two loading rates, a typical agronomic rate (27 Mg hectare−1 year−1) and double the agronomic rate (54 Mg hectare−1 year−1), while synthetic fertilizer was applied at an agronomic rate typical for the region (291 kg N hectare−1 year−1). Both biosolids amendments and synthetic fertilizer increased soil N and corn yield, but only the biosolids amendments resulted in significant increases in nitrification rates and increases in the copy numbers of archaeal and bacterial amoA genes. In addition, only archaeal amoA gene copy numbers increased in response to biosolids applied at the typical agronomic rate and showed a significant correlation with nitrification rates. Finally, copy numbers of archaeal amoA genes were significantly higher than copy numbers of bacterial amoA genes for all treatments. These results implicate AOA as being primarily responsible for the increased nitrification observed in an agricultural soil amended with biosolids. These results also support the hypothesis that physiological differences between AOA and AOB may enable them to occupy distinct ecological niches. PMID:21803892

  9. Minimization of nitrous oxide emission in a pilot-scale oxidation ditch: generation, spatial variation and microbial interpretation.

    PubMed

    Zheng, Maosheng; Tian, Yuhao; Liu, Tang; Ma, Tao; Li, Li; Li, Can; Ahmad, Muhammad; Chen, Qian; Ni, Jinren

    2015-03-01

    Nitrous oxide (N2O) emission from wastewater treatment plants (WWTPs) has received increasing attention. This paper presented how N2O emission was significantly reduced in a pilot-scale Carrousel oxidation ditch under reasonable nitrification and denitrification. N2O emission from the reactor was found as low as 0.027% of influent nitrogen, which was much less than that from other processes. Further measurements on spatial variation of N2O emission in the alternative aerobic/anoxic zones with help of a series of batch experiments demonstrated that about 90% of the emission was contributed by nitrifier denitrification (ND). Moreover, the taxonomic analysis based on high through-put 16S rRNA gene sequencing revealed that the high abundance of denitrifying bacteria and nitrite-oxidizing bacteria (NOB) was responsible for low nitrite accumulations and consequent low N2O emissions. However, N2O generation would be greatly increased upon the normal operation being shocked by either ammonia overload or aeration failure of the oxidation ditch system. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. Analysis of β-Subgroup Proteobacterial Ammonia Oxidizer Populations in Soil by Denaturing Gradient Gel Electrophoresis Analysis and Hierarchical Phylogenetic Probing

    PubMed Central

    Stephen, John R.; Kowalchuk, George A.; Bruns, Mary-Ann V.; McCaig, Allison E.; Phillips, Carol J.; Embley, T. Martin; Prosser, James I.

    1998-01-01

    A combination of denaturing gradient gel electrophoresis (DGGE) and oligonucleotide probing was used to investigate the influence of soil pH on the compositions of natural populations of autotrophic β-subgroup proteobacterial ammonia oxidizers. PCR primers specific to this group were used to amplify 16S ribosomal DNA (rDNA) from soils maintained for 36 years at a range of pH values, and PCR products were analyzed by DGGE. Genus- and cluster-specific probes were designed to bind to sequences within the region amplified by these primers. A sequence specific to all β-subgroup ammonia oxidizers could not be identified, but probes specific for Nitrosospira clusters 1 to 4 and Nitrosomonas clusters 6 and 7 (J. R. Stephen, A. E. McCaig, Z. Smith, J. I. Prosser, and T. M. Embley, Appl. Environ. Microbiol. 62:4147–4154, 1996) were designed. Elution profiles of probes against target sequences and closely related nontarget sequences indicated a requirement for high-stringency hybridization conditions to distinguish between different clusters. DGGE banding patterns suggested the presence of Nitrosomonas cluster 6a and Nitrosospira clusters 2, 3, and 4 in all soil plots, but results were ambiguous because of overlapping banding patterns. Unambiguous band identification of the same clusters was achieved by combined DGGE and probing of blots with the cluster-specific radiolabelled probes. The relative intensities of hybridization signals provided information on the apparent selection of different Nitrosospira genotypes in samples of soil of different pHs. The signal from the Nitrosospira cluster 3 probe decreased significantly, relative to an internal control probe, with decreasing soil pH in the range of 6.6 to 3.9, while Nitrosospira cluster 2 hybridization signals increased with increasing soil acidity. Signals from Nitrosospira cluster 4 were greatest at pH 5.5, decreasing at lower and higher values, while Nitrosomonas cluster 6a signals did not vary significantly with p

  11. Metatranscriptomic and metagenomic description of the bacterial nitrogen metabolism in waste water wet oxidation effluents.

    PubMed

    Crovadore, Julien; Soljan, Vice; Calmin, Gautier; Chablais, Romain; Cochard, Bastien; Lefort, François

    2017-10-01

    Anaerobic digestion is a common method for reducing the amount of sludge solids in used waters and enabling biogas production. The wet oxidation process (WOX) improves anaerobic digestion by converting carbon into methane through oxidation of organic compounds. WOX produces effluents rich in ammonia, which must be removed to maintain the activity of methanogens. Ammonia removal from WOX could be biologically operated by aerobic granules. To this end, granulation experiments were conducted in 2 bioreactors containing an activated sludge (AS). For the first time, the dynamics of the microbial community structure and the expression levels of 7 enzymes of the nitrogen metabolism in such active microbial communities were followed in regard to time by metagenomics and metatranscriptomics. It was shown that bacterial communities adapt to the wet oxidation effluent by increasing the expression level of the nitrogen metabolism, suggesting that these biological activities could be a less costly alternative for the elimination of ammonia, resulting in a reduction of the use of chemicals and energy consumption in sewage plants. This study reached a strong sequencing depth (from 4.4 to 7.6 Gb) and enlightened a yet unknown diversity of the microorganisms involved in the nitrogen pathway. Moreover, this approach revealed the abundance and expression levels of specialised enzymes involved in nitrification, denitrification, ammonification, dissimilatory nitrate reduction to ammonium (DNRA) and nitrogen fixation processes in AS.

  12. Theoretical investigation of aerobic and anaerobic oxidative inactivation of the [NiFe]-hydrogenase active site.

    PubMed

    Breglia, Raffaella; Greco, Claudio; Fantucci, Piercarlo; De Gioia, Luca; Bruschi, Maurizio

    2018-01-17

    The extraordinary capability of [NiFe]-hydrogenases to catalyse the reversible interconversion of protons and electrons into dihydrogen (H 2 ) has stimulated numerous experimental and theoretical studies addressing the direct utilization of these enzymes in H 2 production processes. Unfortunately, the introduction of these natural H 2 -catalysts in biotechnological applications is limited by their inhibition under oxidising (aerobic and anaerobic) conditions. With the aim of contributing to overcome this limitation, we studied the oxidative inactivation mechanism of [NiFe]-hydrogenases by performing Density Functional Theory (DFT) calculations on a very large model of their active site in which all the amino acids forming the first and second coordination spheres of the NiFe cluster have been explicitly included. We identified an O 2 molecule and two H 2 O molecules as sources of the two oxygen atoms that are inserted at the active site of the inactive forms of the enzyme (Ni-A and Ni-B) under aerobic and anaerobic conditions, respectively. Furthermore, our results support the experimental evidence that the Ni-A-to-Ni-B ratio strongly depends on the number of reducing equivalents available for the process and on the oxidizing conditions under which the reaction takes place.

  13. Hypocaloric diet and regular moderate aerobic exercise is an effective strategy to reduce anthropometric parameters and oxidative stress in obese patients.

    PubMed

    Gutierrez-Lopez, Liliana; Garcia-Sanchez, Jose Ruben; Rincon-Viquez, Maria de Jesus; Lara-Padilla, Eleazar; Sierra-Vargas, Martha P; Olivares-Corichi, Ivonne M

    2012-01-01

    Studies show that diet and exercise are important in the treatment of obesity. The aim of this study was to determine whether additional regular moderate aerobic exercise during a treatment with hypocaloric diet has a beneficial effect on oxidative stress and molecular damage in the obese patient. Oxidative stress of 16 normal-weight (NW) and 32 obese 1 (O1) subjects (BMI 30-34.9 kg/m(2)) were established by biomarkers of oxidative stress in plasma. Recombinant human insulin was incubated with blood from NW or O1 subjects, and the molecular damage to the hormone was analyzed. Two groups of treatment, hypocaloric diet (HD) and hypocaloric diet plus regular moderate aerobic exercise (HDMAE), were formed, and their effects in obese subjects were analyzed. The data showed the presence of oxidative stress in O1 subjects. Molecular damage and polymerization of insulin was observed more frequently in the blood from O1 subjects. The treatment of O1 subjects with HD decreased the anthropometric parameters as well as oxidative stress and molecular damage, which was more effectively prevented by the treatment with HDMAE. HD and HDMAE treatments decreased anthropometric parameters, oxidative stress, and molecular damage in O1 subjects. Copyright © 2012 S. Karger GmbH, Freiburg.

  14. Characterization and quantification of ammonia-oxidizing archaea (AOA) and bacteria (AOB) in a nitrogen-removing reactor using T-RFLP and qPCR

    PubMed Central

    Jin, Tao; Yan, Qingmei

    2010-01-01

    Using ammonia monooxygenase α-subunit (amoA) gene and 16S rRNA gene, the community structure and abundance of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in a nitrogen-removing reactor, which was operated for five phases, were characterized and quantified by cloning, terminal restriction fragment length polymorphism (T-RFLP), and quantitative polymerase chain reaction (qPCR). The results suggested that the dominant AOB in the reactor fell to the genus Nitrosomonas, while the dominant AOA belonged to Crenarchaeotal Group I.1a in phylum Crenarchaeota. Real-time PCR results demonstrated that the levels of AOB amoA varied from 2.9 × 103 to 2.3 × 105 copies per nanogram DNA, greatly (about 60 times) higher than those of AOA, which ranged from 1.7 × 102 to 3.8 × 103 copies per nanogram DNA. This indicated the possible leading role of AOB in the nitrification process in this study. T-RFLP results showed that the AOB community structure significantly shifted in different phases while AOA only showed one major peak for all the phases. The analyses also suggested that the AOB community was more sensitive than that of AOA to operational conditions, such as ammonia loading and dissolved oxygen. PMID:20405121

  15. The Bacterial Communities of Full-Scale Biologically Active, Granular Activated Carbon Filters Are Stable and Diverse and Potentially Contain Novel Ammonia-Oxidizing Microorganisms

    PubMed Central

    Hope Wilkinson, Katheryn; Strait, Jacqueline M.; Hozalski, Raymond M.; Sadowksy, Michael J.; Hamilton, Matthew J.

    2015-01-01

    The bacterial community composition of the full-scale biologically active, granular activated carbon (BAC) filters operated at the St. Paul Regional Water Services (SPRWS) was investigated using Illumina MiSeq analysis of PCR-amplified 16S rRNA gene fragments. These bacterial communities were consistently diverse (Shannon index, >4.4; richness estimates, >1,500 unique operational taxonomic units [OTUs]) throughout the duration of the 12-month study period. In addition, only modest shifts in the quantities of individual bacterial populations were observed; of the 15 most prominent OTUs, the most highly variable population (a Variovorax sp.) modulated less than 13-fold over time and less than 8-fold from filter to filter. The most prominent population in the profiles was a Nitrospira sp., representing 13 to 21% of the community. Interestingly, very few of the known ammonia-oxidizing bacteria (AOB; <0.07%) and no ammonia-oxidizing Archaea were detected in the profiles. Quantitative PCR of amoA genes, however, suggested that AOB were prominent in the bacterial communities (amoA/16S rRNA gene ratio, 1 to 10%). We conclude, therefore, that the BAC filters at the SPRWS potentially contained significant numbers of unidentified and novel ammonia-oxidizing microorganisms that possess amoA genes similar to those of previously described AOB. PMID:26209671

  16. Streamlined ammonia removal from wastewater using biological deammonification process

    USDA-ARS?s Scientific Manuscript database

    In this work we evaluated biological deammonification process to more economically remove ammonia from livestock wastewater. The process combines partial nitritation (PN) and anammox. The anammox is a biologically mediated reaction that oxidizes ammonia (NH4+) and releases di-nitrogen gas (N2) unde...

  17. Biological removal of air loaded with a hydrogen sulfide and ammonia mixture.

    PubMed

    Chen, Ying-xu; Yin, Jun; Fang, Shi

    2004-01-01

    The nuisance impact of air pollutant emissions from wastewater pumping stations is a major issue of concern to China. Hydrogen sulfide and ammonia are commonly the primary odor and are important targets for removal. An alternative control technology, biofiltration, was studied. The aim of this study is to investigate the potential of unit systems packed with compost in terms of ammonia and hydrogen sulfide emissions treatment, and to establish optimal operating conditions for a full-scale conceptual design. The laboratory scale biofilter packed with compost was continuously supplied with hydrogen sulfide and ammonia gas mixtures. A volumetric load of less than 150 gH2S/(m3 x d) and 230 gNH3/(m3 x d) was applied for about fifteen weeks. Hydrogen sulfide and ammonia elimination occurred in the biofilter simultaneously. The removal efficiency, removal capacity and removal kinetics in the biofilter were studied. The hydrogen sulfide removal efficiency reached was very high above 99%, and ammonia removal efficiency was about 80%. Hydrogen sulfide was oxidized into sulphate. The ammonia oxidation products were nitrite and nitrate. Ammonia in the biofilter was mainly removed by adsorption onto the carrier material and by absorption into the water fraction of the carrier material. High percentages of hydrogen sulfide or ammonia were oxidized in the first section of the column. Through kinetics analysis, the presence of ammonia did not hinder the hydrogen sulfide removal. According to the relationship between pressure drop and gas velocity for the biofilter and Reynolds number, non-Darcy flow can be assumed to represent the flow in the medium.

  18. Acute effects of intradialytic aerobic exercise on solute removal, blood gases and oxidative stress in patients with chronic kidney disease.

    PubMed

    Böhm, Joseane; Monteiro, Mariane Borba; Andrade, Francini Porcher; Veronese, Francisco Veríssimo; Thomé, Fernando Saldanha

    2017-01-01

    Hemodialysis contributes to increased oxidative stress and induces transitory hypoxemia. Compartmentalization decreases the supply of solutes to the dialyzer during treatment. The aim of this study was to investigate the acute effects of intradialytic aerobic exercise on solute removal, blood gases and oxidative stress in patients with chronic kidney disease during a single hemodialysis session. Thirty patients were randomized to perform aerobic exercise with cycle ergometer for lower limbs during 30 minutes with intensity between 60-70% of maximal heart rate, or control group (CG). Blood samples were collected prior to and immediately after exercise or the equivalent time in CG. Analysis of blood and dialysate biochemistry as well as blood gases were performed. Mass removal and solute clearance were calculated. Oxidative stress was determined by lipid peroxidation and by the total antioxidant capacity. Serum concentrations of solutes increased with exercise, but only phosphorus showed a significant elevation (p = 0.035). There were no significant changes in solute removal and in the acid-base balance. Both oxygen partial pressure and saturation increased with exercise (p = 0.035 and p = 0.024, respectivelly), which did not occur in the CG. The total antioxidant capacity decreased significantly (p = 0.027). The acute intradialytic aerobic exercise increased phosphorus serum concentration and decreased total antioxidant capacity, reversing hypoxemia resulting from hemodialysis. The intradialytic exercise did not change the blood acid-base balance and the removal of solutes.

  19. Aerobic exercise improves oxidant-antioxidant balance in patients with rheumatoid arthritis

    PubMed Central

    Tuna, Zeynep; Duger, Tulin; Atalay-Guzel, Nevin; Aral, Arzu; Basturk, Bilkay; Haznedaroglu, Seminur; Goker, Berna

    2015-01-01

    [Purpose] Although oxidative stress is known to be present in rheumatoid arthritis (RA), the effects of exercise on oxidative parameters are unknown. The aim of this study was to investigate the effects of acute aerobic exercise on serum oxidant and antioxidant levels in patients with RA. [Subjects and Methods] Sixteen patients with RA and 10 age-matched healthy volunteers participated in this study. All participants wore polar telemeters and walked on a treadmill for 30 minutes at a speed eliciting 60–75% of maximal heart rates. Blood samples were obtained before, immediately and 24 hours after exercise and malondialdehyde (MDA) and total sulfhydrile group (RSH) levels were measured. [Results] Both groups had similar heart rates during the test but the treadmill speed of the RA patients was significantly lower than that of the healthy volunteers. Serum MDA levels were lower than in both groups immediately after exercise, with greater decrements in the RA patients than controls. MDA levels returned to baseline 24 hours after the exercise only in the controls; they remained low in the RA patients. There was a slight increase in serum RSH levels after exercise compared to baseline in both groups. [Conclusion] Moderate intensity treadmill exercise did not have any adverse effect on the oxidant-antioxidant balance. The results suggest that such an exercise may be safely added to the rehabilitation program of RA for additional antioxidant effects. Morever, this antioxidant environment is maintained longer in RA patients. PMID:25995597

  20. Oxidative stress and inflammation response following aerobic exercise: role of ethnicity.

    PubMed

    McKenzie, M J; Goldfarb, A; Garten, R S; Vervaecke, L

    2014-09-01

    African-Americans are at a significantly greater risk for developing several diseases and conditions. These conditions often have underlying oxidative stress mechanisms. Therefore the purpose of this investigation was to ascertain the post-exercise oxidative response to a single bout of aerobic exercise in African-American and Caucasian college-age females. A total of 10 African-American and 10 Caucasian females completed the study. Each subject had her VO2 max measured while exercising on a treadmill. A week later, each subject returned to the laboratory and performed a 30-min run at 70% of her VO2max. Blood samples were taken immediately prior to and following exercise for analysis. Lipid hydroperoxides, protein carbonyls, malondialdehyde, xanthine oxidase, glutathione in the reduced (GSH) and oxidized (GSSG) forms, TNFα and interleukin 6 were measured from blood taken before and after exercise. Significance was set at p≤0.05 a priori. Xanthine oxidase was the only measure that did not significantly increase following exercise. All other markers showed a significant elevation in response to the exercise bout with no difference between groups except that the Caucasian group had significantly higher malondialdehyde post-exercise compared to the African-American group. This cohort of college-age African-American and Caucasian females showed little difference in their response to a single 30-min run at 70% of their max in the markers of oxidative stress within the blood. © Georg Thieme Verlag KG Stuttgart · New York.

  1. Simultaneous stripping recovery of ammonia-nitrogen and precipitation of manganese from electrolytic manganese residue by air under calcium oxide assist.

    PubMed

    Chen, Hongliang; Liu, Renlong; Shu, Jiancheng; Li, Wensheng

    2015-01-01

    Leaching tests of electrolytic manganese residue (EMR) indicated that high contents of soluble manganese and ammonia-nitrogen posed a high environmental risk. This work reports the results of simultaneous stripping recovery of ammonia-nitrogen and precipitation of manganese by air under calcium oxide assist. The ammonia-nitrogen stripping rate increased with the dosage of CaO, the air flow rate and the temperature of EMR slurry. Stripped ammonia-nitrogen was absorbed by a solution of sulfuric acid and formed soluble (NH4)2SO4 and (NH4)3H(SO4)3. The major parameters that effected soluble manganese precipitation were the dosage of added CaO and the slurry temperature. Considering these two aspects, the efficient operation conditions should be conducted with 8 wt.% added CaO, 60°C, 800 mL min(-1) air flow rate and 60-min reaction time. Under these conditions 99.99% of the soluble manganese was precipitated as Mn3O4, which was confirmed by XRD and SEM-EDS analyses. In addition, the stripping rate of ammonia-nitrogen was 99.73%. Leaching tests showed the leached toxic substances concentrations of the treated EMR met the integrated wastewater discharge standard of China (GB8978-1996).

  2. Bacterial and archaeal symbionts in the South China Sea sponge Phakellia fusca: community structure, relative abundance, and ammonia-oxidizing populations.

    PubMed

    Han, Minqi; Liu, Fang; Zhang, Fengli; Li, Zhiyong; Lin, Houwen

    2012-12-01

    Many biologically active natural products have been isolated from Phakellia fusca, an indigenous sponge in the South China Sea; however, the microbial symbionts of Phakellia fusca remain unknown. The present investigations on sponge microbial community are mainly based on qualitative analysis, while quantitative analysis, e.g., relative abundance, is rarely carried out, and little is known about the roles of microbial symbionts. In this study, the community structure and relative abundance of bacteria, actinobacteria, and archaea associated with Phakellia fusca were revealed by 16S rRNA gene library-based sequencing and quantitative real time PCR (qRT-PCR). The ammonia-oxidizing populations were investigated based on amoA gene and anammox-specific 16S rRNA gene libraries. As a result, it was found that bacterial symbionts of sponge Phakellia fusca consist of Proteobacteria including Gamma-, Alpha-, and Delta-proteobacteria, Cyanobacteria with Gamma-proteobacteria as the predominant components. In particular, the diversity of actinobacterial symbionts in Phakellia fusca is high, which is composed of Corynebacterineae, Acidimicrobidae, Frankineae, Micrococcineae, and Streptosporangineae. All the observed archaea in sponge Phakellia fusca belong to Crenarchaeota, and the detected ammonia-oxidizing populations are ammonia-oxidizing archaea, suggesting the nitrification function of sponge archaeal symbionts. According to qRT-PCR analysis, bacterial symbionts dominated the microbial community, while archaea represented the second predominant symbionts, followed by actinobacteria. The revealed diverse prokaryotic symbionts of Phakellia fusca are valuable for the understanding and in-depth utilization of Phakellia fusca microbial symbionts. This study extends our knowledge of the community, especially the relative abundance of microbial symbionts in sponges.

  3. Aerobic Oxidation of Xylose to Xylaric acid in Water over Pt Catalysts.

    PubMed

    Saha, Basudeb; Sadula, Sunitha

    2018-05-02

    Energy-efficient catalytic conversion of biomass intermediates to functional chemicals can enable bio-products viable. Herein, we report an efficient and low temperature aerobic oxidation of xylose to xylaric acid, a promising bio-based chemical for the production of glutaric acid, over commercial catalysts in water. Among several heterogeneous catalysts investigated, Pt/C exhibits the best activity. Systematic variation of reaction parameters in the pH range of 2.5 to 10 suggests that the reaction is fast at higher temperatures but high C-C scission of intermediate C5-oxidized products to low carbon carboxylic acids undermines xylaric acid selectivity. The C-C cleavage is also high in basic solution. The oxidation at neutral pH and 60 C achieves the highest xylaric acid yield (64%). O2 pressure and Pt-amount have significant influence on the reactivity. Decarboxylation of short chain carboxylic acids results in formation of CO2, causing some carbon loss; however such decarboxylation is slow in the presence of xylose. The catalyst retained comparable activity, in terms of product selectivity, after five cycles with no sign of Pt leaching. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Comparison among amoA Primers Suited for Quantification and Diversity Analyses of Ammonia-Oxidizing Bacteria in Soil

    PubMed Central

    Shimomura, Yumi; Morimoto, Sho; Hoshino, Yuko Takada; Uchida, Yoshitaka; Akiyama, Hiroko; Hayatsu, Masahito

    2012-01-01

    Ammonia monooxygenase subunit A gene (amoA) is frequently used as a functional gene marker for diversity analysis of ammonia-oxidizing bacteria (AOB). To select a suitable amoA primer for real-time PCR and PCR-denaturing gradient gel electrophoresis (DGGE), three reverse primers (degenerate primer amoA-2R; non-degenerate primers amoA-2R-GG and amoA-2IR) were examined. No significant differences were observed among the three primers in terms of quantitative values of amoA from environmental samples using real-time PCR. We found that PCR-DGGE analysis with the amoA-2IR primer gave the best results in this studied soil. These results indicate that amoA-2IR is a suitable primer for community analysis of AOB in the environment. PMID:22075625

  5. Temporal and spatial distributions of ammonia-oxidizing archaea and bacteria and their ratio as an indicator of oligotrophic conditions in natural wetlands.

    PubMed

    Sims, Atreyee; Horton, John; Gajaraj, Shashikanth; McIntosh, Steve; Miles, Randall J; Mueller, Ryan; Reed, Robert; Hu, Zhiqiang

    2012-09-01

    Ammonia-oxidizing organisms play an important role in wetland water purification and nitrogen cycling. We determined soil nitrification rates and investigated the seasonal and spatial distributions of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in three freshwater wetlands by using specific primers targeting the amoA genes of AOA and AOB and real-time quantitative polymerase chain reaction (qPCR). The nitrifying potentials of wetland soils ranged from 1.4 to 4.0 μg g(-1) day(-1). The specific rates of ammonia oxidation activity by AOA and AOB at the Bee Hollow wetlands were 1.9 fmol NH(3) cell(-1) day(-1) and 36.8 fmol NH(3) cell(-1) day(-1), respectively. Soil nitrification potential was positively correlated with both archaeal and bacterial amoA abundance. However, the gene copies of AOA amoA were higher than those of AOB amoA by at least an order of magnitude in wetland soils and water in both summer and winter over a three year study period. AOB were more sensitive to low temperature than AOA. The amoA gene copy ratios of AOA to AOB in top soils (0-10 cm) ranged from 19 ± 4 to 100 ± 11 among the wetland sites. In contrast, the ratio of the wetland boundary soil was 10 ± 2, which was significantly lower than that of the wetland soils (P < 0.001). The NH(4)(+)-N concentrations in wetland water were lower than 2 mg/L throughout the study. The results suggest that ammonium concentration is a major factor influencing AOA and AOB population in wetlands, although other factors such as temperature, dissolved oxygen, and soil organic matter are involved. AOA are more persistent and more abundant than AOB in the nutrient-depleted oligotrophic wetlands. Therefore, ratio of AOA amoA gene copies to AOB amoA gene copies may serve as a new biological indicator for wetland condition assessment and wetland restoration applications. Copyright © 2012 Elsevier Ltd. All rights reserved.

  6. Aerobic treatment of swine manure to enhance anaerobic digestion and microalgal cultivation.

    PubMed

    Bekoe, Dominic; Wang, Lijun; Zhang, Bo; Scott Todd, Matthew; Shahbazi, Abolghasem

    2018-02-01

    Aerobic treatment of swine manure was coupled with anaerobic digestion and microalgal cultivation. A 14-day aerobic treatment reduced the total solid content of swine manure by >15%. Ammonia and carbon dioxide were stripped by the air supplied, and this off-gas was further used to aerate the culture of Chlorella vulgaris. The microalgal growth rates in Bristol medium and the wastewater with the off-gas increased from 0.08 to 0.22 g/L/d and from 0.15 to 0.24 g/L/d, respectively. Meanwhile, the aerobically treated swine manure showed a higher methane yield during anaerobic digestion. The experimental results were used to establish a demonstration unit consisting of a 100 L composter, a 200 L anaerobic digester, a 60 L tubular photobioreactor, and a 300 L micro-open raceway pond.

  7. Detoxification of ammonia in mouse cortical GABAergic cell cultures increases neuronal oxidative metabolism and reveals an emerging role for release of glucose-derived alanine.

    PubMed

    Leke, Renata; Bak, Lasse K; Anker, Malene; Melø, Torun M; Sørensen, Michael; Keiding, Susanne; Vilstrup, Hendrik; Ott, Peter; Portela, Luis V; Sonnewald, Ursula; Schousboe, Arne; Waagepetersen, Helle S

    2011-04-01

    Cerebral hyperammonemia is believed to play a pivotal role in the development of hepatic encephalopathy (HE), a debilitating condition arising due to acute or chronic liver disease. In the brain, ammonia is thought to be detoxified via the activity of glutamine synthetase, an astrocytic enzyme. Moreover, it has been suggested that cerebral tricarboxylic acid (TCA) cycle metabolism is inhibited and glycolysis enhanced during hyperammonemia. The aim of this study was to characterize the ammonia-detoxifying mechanisms as well as the effects of ammonia on energy-generating metabolic pathways in a mouse neuronal-astrocytic co-culture model of the GABAergic system. We found that 5 mM ammonium chloride affected energy metabolism by increasing the neuronal TCA cycle activity and switching the astrocytic TCA cycle toward synthesis of substrate for glutamine synthesis. Furthermore, ammonia exposure enhanced the synthesis and release of alanine. Collectively, our results demonstrate that (1) formation of glutamine is seminal for detoxification of ammonia; (2) neuronal oxidative metabolism is increased in the presence of ammonia; and (3) synthesis and release of alanine is likely to be important for ammonia detoxification as a supplement to formation of glutamine.

  8. Niche segregation of ammonia-oxidizing archaea and anammox bacteria in the Arabian Sea oxygen minimum zone

    PubMed Central

    Pitcher, Angela; Villanueva, Laura; Hopmans, Ellen C; Schouten, Stefan; Reichart, Gert-Jan; Sinninghe Damsté, Jaap S

    2011-01-01

    Ammonia-oxidizing archaea (AOA) and anaerobic ammonia-oxidizing (anammox) bacteria have emerged as significant factors in the marine nitrogen cycle and are responsible for the oxidation of ammonium to nitrite and dinitrogen gas, respectively. Potential for an interaction between these groups exists; however, their distributions are rarely determined in tandem. Here we have examined the vertical distribution of AOA and anammox bacteria through the Arabian Sea oxygen minimum zone (OMZ), one of the most intense and vertically exaggerated OMZs in the global ocean, using a unique combination of intact polar lipid (IPL) and gene-based analyses, at both DNA and RNA levels. To screen for AOA-specific IPLs, we developed a high-performance liquid chromatography/mass spectrometry/mass spectrometry method targeting hexose-phosphohexose (HPH) crenarchaeol, a common IPL of cultivated AOA. HPH-crenarchaeol showed highest abundances in the upper OMZ transition zone at oxygen concentrations of ca. 5 μ, coincident with peaks in both thaumarchaeotal 16S rDNA and amoA gene abundances and gene expression. In contrast, concentrations of anammox-specific IPLs peaked within the core of the OMZ at 600 m, where oxygen reached the lowest concentrations, and coincided with peak anammox 16S rDNA and the hydrazine oxidoreductase (hzo) gene abundances and their expression. Taken together, the data reveal a unique depth distribution of abundant AOA and anammox bacteria and the segregation of their respective niches by >400 m, suggesting no direct coupling of their metabolisms at the time and site of sampling in the Arabian Sea OMZ. PMID:21593795

  9. SBA-15-functionalized 3-oxo-ABNO as recyclable catalyst for aerobic oxidation of alcohols under metal-free conditions.

    PubMed

    Karimi, Babak; Farhangi, Elham; Vali, Hojatollah; Vahdati, Saleh

    2014-09-01

    The nitroxyl radical 3-oxo-9-azabicyclo [3.3.1]nonane-N-oxyl (3-oxo-ABNO) has been prepared using a simple protocol. This organocatalyst is found to be an efficient catalyst for the aerobic oxidation of a wide variety of alcohols under metal-free conditions. In addition, the preparation and characterization of a supported version of 3-oxo-ABNO on ordered mesoporous silica SBA-15 (SABNO) is described for the first time. The catalyst has been characterized using several techniques including simultaneous thermal analysis (STA), transmission electron microscopy (TEM), and nitrogen sorption analysis. This catalyst exhibits catalytic performance comparable to its homogeneous analogue and much superior catalytic activity in comparison with (2,2,6,6-tetramethylpiperidin-1-yl)oxy (TEMPO) for the aerobic oxidation of almost the same range of alcohols under identical reaction conditions. It is also found that SABNO can be conveniently recovered and reused at least 12 times without significant effect on its catalytic efficiency. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. amoA Gene Abundances and Nitrification Potential Rates Suggest that Benthic Ammonia-Oxidizing Bacteria and Not Archaea Dominate N Cycling in the Colne Estuary, United Kingdom

    PubMed Central

    Li, Jialin; Nedwell, David B.; Beddow, Jessica; Dumbrell, Alex J.; McKew, Boyd A.; Thorpe, Emma L.

    2014-01-01

    Nitrification, mediated by ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA), is important in global nitrogen cycling. In estuaries where gradients of salinity and ammonia concentrations occur, there may be differential selections for ammonia-oxidizer populations. The aim of this study was to examine the activity, abundance, and diversity of AOA and AOB in surface oxic sediments of a highly nutrified estuary that exhibits gradients of salinity and ammonium. AOB and AOA communities were investigated by measuring ammonia monooxygenase (amoA) gene abundance and nitrification potentials both spatially and temporally. Nitrification potentials differed along the estuary and over time, with the greatest nitrification potentials occurring mid-estuary (8.2 μmol N grams dry weight [gdw]−1 day−1 in June, increasing to 37.4 μmol N gdw−1 day−1 in January). At the estuary head, the nitrification potential was 4.3 μmol N gdw−1 day−1 in June, increasing to 11.7 μmol N gdw−1 day−1 in January. At the estuary head and mouth, nitrification potentials fluctuated throughout the year. AOB amoA gene abundances were significantly greater (by 100-fold) than those of AOA both spatially and temporally. Nitrosomonas spp. were detected along the estuary by denaturing gradient gel electrophoresis (DGGE) band sequence analysis. In conclusion, AOB dominated over AOA in the estuarine sediments, with the ratio of AOB/AOA amoA gene abundance increasing from the upper (freshwater) to lower (marine) regions of the Colne estuary. These findings suggest that in this nutrified estuary, AOB (possibly Nitrosomonas spp.) were of major significance in nitrification. PMID:25326303

  11. amoA Gene abundances and nitrification potential rates suggest that benthic ammonia-oxidizing bacteria and not Archaea dominate N cycling in the Colne Estuary, United Kingdom.

    PubMed

    Li, Jialin; Nedwell, David B; Beddow, Jessica; Dumbrell, Alex J; McKew, Boyd A; Thorpe, Emma L; Whitby, Corinne

    2015-01-01

    Nitrification, mediated by ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA), is important in global nitrogen cycling. In estuaries where gradients of salinity and ammonia concentrations occur, there may be differential selections for ammonia-oxidizer populations. The aim of this study was to examine the activity, abundance, and diversity of AOA and AOB in surface oxic sediments of a highly nutrified estuary that exhibits gradients of salinity and ammonium. AOB and AOA communities were investigated by measuring ammonia monooxygenase (amoA) gene abundance and nitrification potentials both spatially and temporally. Nitrification potentials differed along the estuary and over time, with the greatest nitrification potentials occurring mid-estuary (8.2 μmol N grams dry weight [gdw](-1) day(-1) in June, increasing to 37.4 μmol N gdw(-1) day(-1) in January). At the estuary head, the nitrification potential was 4.3 μmol N gdw(-1) day(-1) in June, increasing to 11.7 μmol N gdw(-1) day(-1) in January. At the estuary head and mouth, nitrification potentials fluctuated throughout the year. AOB amoA gene abundances were significantly greater (by 100-fold) than those of AOA both spatially and temporally. Nitrosomonas spp. were detected along the estuary by denaturing gradient gel electrophoresis (DGGE) band sequence analysis. In conclusion, AOB dominated over AOA in the estuarine sediments, with the ratio of AOB/AOA amoA gene abundance increasing from the upper (freshwater) to lower (marine) regions of the Colne estuary. These findings suggest that in this nutrified estuary, AOB (possibly Nitrosomonas spp.) were of major significance in nitrification. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  12. [Moderately haloalkaliphilic aerobic methylobacteria].

    PubMed

    Trotsenko, Iu A; Doronina, N V; Li, Ts D; Reshetnikov, A S

    2007-01-01

    Aerobic methylobacteria utilizing oxidized and substituted methane derivatives as carbon and energy sources are widespread in nature and involved in the global carbon cycle, being a unique biofilter on the path of these C1 compounds from different ecosystems to the atmosphere. New data on the biological features of moderately halophilic, neutrophilic, and alkaliphilic methylobacteria isolated from biotopes with higher osmolarity (seas, saline and soda lakes, saline soils, and deteriorating marble) are reviewed. Particular attention is paid to the latest advances in the study of the mechanisms of osmoadaptation of aerobic moderately haloalkaliphilic methylobacteria: formation of osmolytes, in particular, molecular and genetic aspects of biosynthesis of the universal bioprotectant ectoine. The prospects for further studies of the physiological and biochemical principles of haloalkalophily and for the application of haloalkaliphilic aerobic methylobacteria in biosynthesis and biodegradation are discussed.

  13. The Significance of Myriophyllum elatinoides for Swine Wastewater Treatment: Abundance and Community Structure of Ammonia-Oxidizing Microorganisms in Sediments

    PubMed Central

    Li, Xi; Zhang, Miaomiao; Liu, Feng; Li, Yong; He, Yang; Zhang, Shunan; Wu, Jinshui

    2015-01-01

    Myriophyllum elatinoides was reported to effectively treat wastewater by removing nitrogen (N) and phosphorus (P). However, little is known about the abundance and community structure of ammonia-oxidizing microorganisms associated with M. elatinoides purification systems. The objective of this research was to characterize the abundance and community structure of ammonia-oxidizing microorganisms in swine wastewater and determine the main nitrogen removal pathways. In this study, five different waters were treated by M. elatinoides in microcosms for one month. The five waters included tap water (Control), swine wastewater (SW), 50% diluted swine wastewater (50% SW), and two synthetic wastewaters: 200 mg NH4 +-N L−1 (200 NH4 +-N) and 400 mg NH4 +-N L−1 (400 NH4 +-N). The most dramatic changes were in NH4 +-N and total N (TN) concentrations, with average removal rates of 84% and 90%, respectively, in the treatments containing swine wastewater. On days 7, 14, and 28, the dissolved oxygen (DO) increased by 81.8%, 210.4% and 136.5%, respectively, compared with on day 0, in the swine wastewater. The results also showed that the bacterial amoA (AOB) copy numbers in the sediments of the treatments were significantly higher than those of archaeal amoA (AOA) copy numbers (p = 0.015). In addition, the high DO concentrations in swine wastewater responded well to the high abundance of AOB. The AOA and AOB community distributions were positively related with NO3 -N and were negatively related with DO in swine wastewater treatments. In summary, our experimental results suggested that the M. elatinoides purification system could improve the activity of ammonia-oxidizing microorganisms and consequently might contribute to the significant N removal from the swine wastewater. PMID:26444015

  14. The Significance of Myriophyllum elatinoides for Swine Wastewater Treatment: Abundance and Community Structure of Ammonia-Oxidizing Microorganisms in Sediments.

    PubMed

    Li, Xi; Zhang, Miaomiao; Liu, Feng; Li, Yong; He, Yang; Zhang, Shunan; Wu, Jinshui

    2015-01-01

    Myriophyllum elatinoides was reported to effectively treat wastewater by removing nitrogen (N) and phosphorus (P). However, little is known about the abundance and community structure of ammonia-oxidizing microorganisms associated with M. elatinoides purification systems. The objective of this research was to characterize the abundance and community structure of ammonia-oxidizing microorganisms in swine wastewater and determine the main nitrogen removal pathways. In this study, five different waters were treated by M. elatinoides in microcosms for one month. The five waters included tap water (Control), swine wastewater (SW), 50% diluted swine wastewater (50% SW), and two synthetic wastewaters: 200 mg NH4+-N L(-1) (200 NH4+-N) and 400 mg NH4+-N L(-1) (400 NH4+-N). The most dramatic changes were in NH4+-N and total N (TN) concentrations, with average removal rates of 84% and 90%, respectively, in the treatments containing swine wastewater. On days 7, 14, and 28, the dissolved oxygen (DO) increased by 81.8%, 210.4% and 136.5%, respectively, compared with on day 0, in the swine wastewater. The results also showed that the bacterial amoA (AOB) copy numbers in the sediments of the treatments were significantly higher than those of archaeal amoA (AOA) copy numbers (p = 0.015). In addition, the high DO concentrations in swine wastewater responded well to the high abundance of AOB. The AOA and AOB community distributions were positively related with NO3-N and were negatively related with DO in swine wastewater treatments. In summary, our experimental results suggested that the M. elatinoides purification system could improve the activity of ammonia-oxidizing microorganisms and consequently might contribute to the significant N removal from the swine wastewater.

  15. Uniform distributions of glucose oxidation and oxygen extraction in gray matter of normal human brain: No evidence of regional differences of aerobic glycolysis.

    PubMed

    Hyder, Fahmeed; Herman, Peter; Bailey, Christopher J; Møller, Arne; Globinsky, Ronen; Fulbright, Robert K; Rothman, Douglas L; Gjedde, Albert

    2016-05-01

    Regionally variable rates of aerobic glycolysis in brain networks identified by resting-state functional magnetic resonance imaging (R-fMRI) imply regionally variable adenosine triphosphate (ATP) regeneration. When regional glucose utilization is not matched to oxygen delivery, affected regions have correspondingly variable rates of ATP and lactate production. We tested the extent to which aerobic glycolysis and oxidative phosphorylation power R-fMRI networks by measuring quantitative differences between the oxygen to glucose index (OGI) and the oxygen extraction fraction (OEF) as measured by positron emission tomography (PET) in normal human brain (resting awake, eyes closed). Regionally uniform and correlated OEF and OGI estimates prevailed, with network values that matched the gray matter means, regardless of size, location, and origin. The spatial agreement between oxygen delivery (OEF≈0.4) and glucose oxidation (OGI ≈ 5.3) suggests that no specific regions have preferentially high aerobic glycolysis and low oxidative phosphorylation rates, with globally optimal maximum ATP turnover rates (VATP ≈ 9.4 µmol/g/min), in good agreement with (31)P and (13)C magnetic resonance spectroscopy measurements. These results imply that the intrinsic network activity in healthy human brain powers the entire gray matter with ubiquitously high rates of glucose oxidation. Reports of departures from normal brain-wide homogeny of oxygen extraction fraction and oxygen to glucose index may be due to normalization artefacts from relative PET measurements. © The Author(s) 2016.

  16. An intercomparison of five ammonia measurement techniques

    NASA Technical Reports Server (NTRS)

    Williams, E. J.; Sandholm, S. T.; Bradshaw, J. D.; Schendel, J. S.; Langford, A. O.; Quinn, P. K.; Lebel, P. J.; Vay, S. A.; Roberts, P. D.; Norton, R. B.

    1992-01-01

    Results obtained from five techniques for measuring gas-phase ammonia at low concentration in the atmosphere are compared. These methods are: (1) a photofragmentation/laser-induced fluorescence (PF/LIF) instrument; (2) a molybdenum oxide annular denuder sampling/chemiluminescence detection technique; (3) a tungsten oxide denuder sampling/chemiluminescence detection system; (4) a citric-acid-coated denuder sampling/ion chromatographic analysis (CAD/IC) method; and (5) an oxalic-acid-coated filter pack sampling/colorimetric analysis method. It was found that two of the techniques, the PF/LIF and the CAD/IC methods, measured approximately 90 percent of the calculated ammonia added in the spiking tests and agreed very well with each other in the ambient measurements.

  17. Ammonia oxidizer populations vary with nitrogen cycling across a tropical montane mean annual temperature gradient.

    PubMed

    Pierre, S; Hewson, I; Sparks, J P; Litton, C M; Giardina, C; Groffman, P M; Fahey, T J

    2017-07-01

    Functional gene approaches have been used to better understand the roles of microbes in driving forest soil nitrogen (N) cycling rates and bioavailability. Ammonia oxidation is a rate limiting step in nitrification, and is a key area for understanding environmental constraints on N availability in forests. We studied how increasing temperature affects the role of ammonia oxidizing archaea (AOA) and bacteria (AOB) in soil N cycling and availability by using a highly constrained natural mean annual temperature (MAT) elevation gradient in a tropical montane wet forest. We found that net nitrate (NO 3 - ) bioavailability is positively related to MAT (r 2  = 0.79, P = 0.0033), and AOA DNA abundance is positively related to both NO 3 - availability (r 2  = 0.34, P = 0.0071) and MAT (r 2  = 0.34, P < 0.001). In contrast, AOB DNA was only detected in some soils across the gradient. We identified three distinct phylotypes within the AOA which differed from one another in abundance and relative gene expression. In addition, one AOA phylotype increased in abundance with MAT, while others did not. We conclude that MAT is the primary driver of ecosystem N availability across this gradient, and AOA population size and structure appear to mediate the relationship between the nitrification and N bioavailability. These findings hold important implications for nutrient limitation in forests and feedbacks to primary production under changing climate. © 2017 by the Ecological Society of America.

  18. Dissimilatory perchlorate reduction linked to aerobic methane oxidation via chlorite dismutase

    NASA Astrophysics Data System (ADS)

    Oremland, R. S.; Baesman, S. M.; Miller, L. G.

    2013-12-01

    The presence of methane (CH4) in the atmosphere of Mars is controversial yet the evidence has aroused scientific interest, as CH4 could be a harbinger of extant or extinct microbial life. There are various oxidized compounds present on the surface of Mars that could serve as electron acceptors for the anaerobic oxidation of CH4, including perchlorate (ClO4-). We examined the role of perchlorate, chlorate (ClO3-) and chlorite (ClO2-) as oxidants linked to CH4 oxidation. Dissimilatory perchlorate reduction begins with reduction of ClO4- to ClO2- and ends with dismutation of chlorite to yield chloride (Cl-) and molecular oxygen (O2). We explored the potential for aerobic CH4 oxidizing bacteria to couple with oxygen derived from chlorite dismutation during dissimilatory perchlorate reduction. Methane (0.2 kPa) was completely removed within several days from the N2-flushed headspace above cell suspensions of methanotrophs (Methylobacter albus strain BG8) and perchlorate reducing bacteria (Dechloromonas agitata strain CKB) in the presence of 5 mM ClO2-. Similar rates of CH4 consumption were observed for these mixed cultures whether they were co-mingled or segregated under a common headspace, indicating that direct contact of cells was not required for methane consumption to occur. We also observed complete removal of 0.2 kPa CH4 in bottles containing dried soil (enriched in methanotrophs by CH4 additions over several weeks) and D. agitata CKB and in the presence of 10 mM ClO2-. This soil (seasonally exposed sediment) collected from the shoreline of a freshwater lake (Searsville Lake, CA) demonstrated endogenous CH4 uptake as well as perchlorate, chlorate and chlorite reduction/dismutation. However, these experiments required physical separation of soil from the aqueous bacterial culture to allow for the partitioning of O2 liberated from chlorite dismutation into the shared headspace. Although dissimilatory reduction of ClO4- and ClO3- could be inferred from the

  19. Interactive effects of multiple climate change factors on ammonia oxidizers and denitrifiers in a temperate steppe.

    PubMed

    Zhang, Cui-Jing; Shen, Ju-Pei; Sun, Yi-Fei; Wang, Jun-Tao; Zhang, Li-Mei; Yang, Zhong-Ling; Han, Hong-Yan; Wan, Shi-Qiang; He, Ji-Zheng

    2017-04-01

    Global climate change could have profound effects on belowground microbial communities and subsequently affect soil biogeochemical processes. The interactive effects of multiple co-occurring climate change factors on microbially mediated processes are not well understood. A four-factorial field experiment with elevated CO2, watering, nitrogen (N) addition and night warming was conducted in a temperate steppe of northern China. Real-time polymerase chain reaction and terminal-restriction fragment length polymorphism, combined with clone library techniques, were applied to examine the effects of those climate change factors on N-related microbial abundance and community composition. Only the abundance of ammonia-oxidizing bacteria significantly increased by nitrogen addition and decreased by watering. The interactions of watering × warming on the bacterial amoA community and warming × nitrogen addition on the nosZ community were found. Redundancy analysis indicated that the ammonia-oxidizing archaeal community was affected by total N and total carbon, while the community of bacterial amoA and nosZ were significantly affected by soil pH. According to a structural equation modeling analysis, climate change influenced net primary production indirectly by altering microbial abundance and activities. These results indicated that microbial responses to the combination of chronic global change tend to be smaller than expected from single-factor global change manipulations. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  20. High-Performance Wireless Ammonia Gas Sensors Based on Reduced Graphene Oxide and Nano-Silver Ink Hybrid Material Loaded on a Patch Antenna.

    PubMed

    Wu, Bian; Zhang, Xingfei; Huang, Beiju; Zhao, Yutong; Cheng, Chuantong; Chen, Hongda

    2017-09-09

    Reduced graphene oxide (rGO) has been studied as a resistive ammonia gas sensor at room temperature. The sensitive hybrid material composed of rGO and nano-silver ink (Ag-ink) was loaded on a microstrip patch antenna to realize high-performance wireless ammonia sensors. The material was investigated using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Firstly, interdigital electrodes (IDEs) printed on the polyethylene terephthalate (PET) by direct printing were employed to measure the variation of resistance of the sensitive material with the ammonia concentration. The results indicated the response of sensor varied from 4.25% to 14.7% under 15-200 ppm ammonia concentrations. Furthermore, the hybrid material was loaded on a microstrip patch antenna fabricated by a conventional printed circuit board (PCB) process, and a 10 MHz frequency shift of the sensor antenna could be observed for 200 ppm ammonia gas. Finally, the wireless sensing property of the sensor antenna was successfully tested using the same emitted antenna outside the gas chamber with a high gain of 5.48 dBi, and an increased reflection magnitude of the emitted antenna due to the frequency mismatch of the sensor antenna was observed. Therefore, wireless ammonia gas sensors loaded on a patch antenna have significant application prospects in the field of Internet of Things (IoTs).