Publications
| Title | Abstract | Year(sorted ascending) Filter | PMID Filter |
|---|
| long-chain n-acyltyrosine synthases from environmental dna. | the heterologous expression of dna extracted directly from environmental samples (environmental dna [edna]) in easily cultured hosts provides access to natural products produced by previously inaccessible microorganisms. when edna cosmid libraries were screened in escherichia coli for antibacterially active clones, long-chain n-acyltyrosine-producing clones were found in every edna library. these apparently common natural products have not been previously described from screening extracts of cul ... | 2004 | 15528554 |
| nitrogen removal from sludge reject water by a two-stage oxygen-limited autotrophic nitrification denitrification process. | nitrogen removal from sludge reject water was obtained by oxygen-limited partial nitritation resulting in nitrite accumulation in a first stage, followed by autotrophic denitrification of nitrite with ammonium as electron donor (similar to anaerobic ammonium oxidation) in a second stage. two membrane-assisted bioreactors (mbrs) were used in series to operate with high sludge ages and subsequent high volumetric loading rates, achieving 1.45 kg n m(-3) day(-1) for the partial nitritation mbr and 1 ... | 2004 | 15137407 |
| fluorescence in situ hybridization analysis of nitrifiers in piggery wastewater treatment reactors. | fluorescence in situ hybridization (fish) was performed to analyze the nitrifying microbial communities in an activated sludge reactor (asr) and a fixed biofilm reactor (fbr) for piggery wastewater treatment. heterotrophic oxidation and nitrification were occurring simultaneously in the asr and the cod and nitrification efficiencies depend on the loads. in the fbr nitrification efficiency also depends on ammonium load to the reactor and nitrite was accumulated when free ammonia concentration was ... | 2004 | 15137442 |
| effects of seawater salinity on nitrite accumulation in short-range nitrification to nitrite as end product. | the effect of seawater salinity on nitrite accumulation in short-range nitrification to nitrite as the end product was studied by using a sbr. experimental results indicated that the growth of nitrobacteria was inhibited and very high levels of nitrite accumulation at different salinities were achieved under the conditions of 25-28 degrees c, ph 7.5-8.0, and the influent ammonia nitrogen of 40-70 mg/l when seawater flow used to flush toilet was less than 35% (salinity 12393 mg/l, cl- 6778 mg/l) ... | 2004 | 15137648 |
| biodegradation of natural and synthetic estrogens by nitrifying activated sludge and ammonia-oxidizing bacterium nitrosomonas europaea. | this report describes the uses of nitrifying activated sludge (nas) and ammonia-oxidizing bacterium nitrosomonas europaea to significantly degrade estrone (e1), 17beta-estradiol (e2), estriol (e3), and 17alpha-ethynylestradiol (ee2). using nas, the degradation of estrogens obeyed first-order reaction kinetics with degradation rate constants of 0.056 h(-1) for e1, 1.3 h(-1) for e2, 0.030 h(-1) for e3, and 0.035 h(-1) for ee2, indicating that e2 was most easily degraded. then, we confirmed that e2 ... | 2004 | 15142793 |
| the transcription of the cbb operon in nitrosomonas europaea. | nitrosomonas europaea is an aerobic ammonia-oxidizing bacterium that participates in the c and n cycles. n. europaea utilizes co(2) as its predominant carbon source, and is an obligate chemolithotroph, deriving all the reductant required for energy and biosynthesis from the oxidation of ammonia (nh(3)) to nitrite (). this bacterium fixes carbon via the calvin-benson-bassham (cbb) cycle via a type i ribulose bisphosphate carboxylase/oxygenase (rubisco). the rubisco operon is composed of five gene ... | 2004 | 15184573 |
| nitrosomonas europaea expresses a nitric oxide reductase during nitrification. | in this paper, we report the identification of a norcbqd gene cluster that encodes a functional nitric oxide reductase (nor) in nitrosomonas europaea. disruption of the norb gene resulted in a strongly diminished nitric oxide (no) consumption by cells and membrane protein fractions, which was restored by the introduction of an intact norcbqd gene cluster in trans. norb-deficient cells produced amounts of nitrous oxide (n2o) equal to that of wild-type cells. norcb-dependent activity was present d ... | 2004 | 15205449 |
| nitrification and anammox with urea as the energy source. | urea is present in many ecosystems and can be used as an energy source by chemolithotrophic aerobic ammonia oxidizing bacteria (aob). thus the utilization of urea in comparison to ammonia, by aob as well as anaerobic ammonia oxidizing (anammox) bacteria was investigated, using enrichments cultures, inoculated with activated sludge, and molecular ecological methods. in batch enrichment cultures grown with ammonia a population established in 2 weeks, which was dominated by halophilic and halotoler ... | 2004 | 15214631 |
| phylogenetic analysis of nitric oxide reductase gene homologues from aerobic ammonia-oxidizing bacteria. | nitric oxide (no) and nitrous oxide (n2o) are climatically important trace gases that are produced by both nitrifying and denitrifying bacteria. in the denitrification pathway, n2o is produced from nitric oxide (no) by the enzyme nitric oxide reductase (nor). the ammonia-oxidizing bacterium nitrosomonas europaea also possesses a functional nitric oxide reductase, which was shown recently to serve a unique function. in this study, sequences homologous to the large subunit of nitric oxide reductas ... | 2004 | 16329906 |
| elevated salinity selects for a less diverse ammonia-oxidizing population in aquarium biofilters. | the activity and changes in the structure of the community of the ammonia-oxidizing bacteria belonging to the betaproteobacteria were monitored in freshwater and artificial seawater biofilters for two months after inoculation with a commercial nitrifying consortium. both in freshwater and artificial seawater, ammonium oxidation proceeded immediately after addition of the inoculum, although initial activity in artificial seawater was lower than in freshwater. denaturing gradient gel electrophores ... | 2004 | 16329887 |
| nitrification and occurrence of salt-tolerant nitrifying bacteria in the negev desert soils. | ammonia oxidation potential, major ammonia oxidizers and occurrence of salt-tolerant nitrifying bacteria were studied in soil samples collected from diverse ecosystems along the northern negev desert. great diversity in ammonia oxidation potential was observed among the soil samples, and ammonia oxidizers were the rate-limiting step of nitrification. denaturing gradient gel electrophoresis and partial 16s rrna gene sequences indicate that members of the genus nitrosospira are the major ammonia o ... | 2004 | 16329889 |
| community analysis of ammonia oxidizer in the oxygen-limited nitritation stage of oland system by dgge of pcr amplified 16s rdna fragments and fish. | oland (oxygen limited autotrophic nitrification and denitrification) nitrogen removal system was constructed by coupling with oxygen limited nitritation stage and anaerobic ammonium oxidation stage. ammonia oxidizer, as a kind of key bacteria in n cycle, plays an important role at the oxygen limited nitritation stage of oland nitrogen removal system. in this study, specific amplification of 16s rdna fragment of ammonia oxidizer by nested pcr, separation of mixed pcr samples by denaturing gradien ... | 2004 | 15559824 |
| nitrosomonas communis strain ynsra, an ammonia-oxidizing bacterium, isolated from the reed rhizoplane in an aquaponics plant. | an ammonia-oxidizing bacterium (strain ynsra) was isolated from the rhizoplane of the reed (phragmites communis) used in an aquaponics plant which is a wastewater treatment plant. strain ynsra was identified as nitrosomonas communis by taxonomic studies. the hydroxylamine-cytochrome c reductase (hcr) of strain ynsra was found to have a higher activity (25.60 u/mg) than that of nitrosomonas europaea atcc25978t (8.94 u/mg). ribulose-1,5-bisphosphate carboxylase (rubisco) activity was detected at v ... | 2004 | 16233712 |
| expression of nitrite reductase in nitrosomonas europaea involves nsrr, a novel nitrite-sensitive transcription repressor. | production of nitric oxide (no) and nitrous oxide (n(2)o) by ammonia (nh(3))-oxidizing bacteria in natural and man-made habitats is thought to contribute to the undesirable emission of no and n(2)o into the earth's atmosphere. the nh(3)-oxidizing bacterium nitrosomonas europaea expresses nitrite reductase (nirk), an enzyme that has so far been studied predominantly in heterotrophic denitrifying bacteria where it is involved in the production of these nitrogenous gases. the finding of nirk homolo ... | 2004 | 15458412 |
| development of nitrogen-removal bioreactor using poly(lactic acid) as an energy source. | to control nitrogen such as ammonia in a rearing water of aquatic animals, we developed new bioreactor capable of both nitrification and denitrification. it was consisted of gel-plate immobilized microorganisms and a biodegradable plastic plate composed of three kind of poly(lactic acid) as an energy source of denitrification. when batch treatment experiment by the bioreactor was continuously carried out with an artificial rearing water containing ammonia, nitrogen-removal rate of the bioreactor ... | 2004 | 15858361 |
| transmembrane transcriptional control (surface signalling) of the escherichia coli fec type. | the ferric citrate transport system of escherichia coli is the first example of a transcription initiation mechanism that starts at the cell surface. the inducer, ferric citrate, binds to an outer membrane transport protein, and without further transport elicits a signal that is transmitted across the outer membrane, the periplasm, and the cytoplasmic membrane into the cytoplasm. signal transfer across the three subcellular compartments is mediated by the outer membrane transport protein that in ... | 2004 | 16102597 |
| autotrophic ammonia oxidation in a deep-sea hydrothermal plume. | direct evidence for autotrophic ammonia oxidation is documented for the first time in a deep-sea hydrothermal plume. elevated nh(4) (+) concentrations of up to 341+/-136 nm were recorded in the plume core at main endeavour field, juan de fuca ridge. this fueled autotrophic ammonia oxidation rates as high as 91 nm day(-1), or 92% of the total net nh(4) (+) removal. high abundance of ammonia-oxidizing bacteria was detected using fluorescence in situ hybridization. ammonia-oxidizing bacteria within ... | 2004 | 19712334 |
| acetylene and oxygen as inhibitors of nitrous oxide production in nitrosomonas europaea and nitrosospira briensis: a cautionary tale. | autotrophic ammonia-oxidizing bacteria produce nitrous oxide (n(2)o) as a by-product of nitrification or as an intermediate of nitrifier denitrification. in soil incubations, acetylene (c(2)h(2)) and large partial pressures of oxygen (o(2)) are used to distinguish between these sources. c(2)h(2) inhibits ammonia oxidation and should therefore inhibit n(2)o production by both nitrification and nitrifier denitrification. o(2) suppresses the reduction pathway of nitrifier denitrification. however, ... | 2004 | 19712342 |
| nitrification-denitrification dynamics and community structure of ammonia oxidizing bacteria in a high yield irrigated philippine rice field. | nitrogen is the single most limiting factor for rice production. detailed knowledge on nitrogen dynamics in rice fields is therefore of major importance for developing sustainable rice production. a combination of state-of-the-art microsensor, stable isotope tracer, and molecular techniques was used to evaluate coupled nitrification-denitrification potentials and community structure of ammonia-oxidizing bacteria in a high yield irrigated rice cropping system in the philippines, without the use o ... | 2004 | 19712286 |
| calcium carbonate phosphate binding ion exchange filtration and accelerated denitrification improve public health standards and combat eutrophication in aquatic ecosystems. | cultural eutrophication, the process by which a lake becomes rich in dissolved nutrients as a result of point and nonpoint pollutant sources, is a major cause of the loss of natural lake ecosystems throughout the world. the process occurs naturally in all lakes, but phosphate-rich nutrient runoff from sources such as storm drains and agricultural runoff is a major cause of excess phosphate-induced eutrophication. especially in madrona marsh, one of the last remaining vernal marshes in the greate ... | 2005 | 16381147 |
| pilot-scale studies on biological treatment of hypersaline wastewater at low temperature. | in order to investigate the feasibility of biological treatment of hypersaline wastewater produced from toilet flushing with seawater at low temperature, pilot-scale studies were established with plug-flow activated sludge process at low temperature (5-9 degrees c) based on bench-scale experiments. the critical salinity concentration of 30 g/l, which resulted from the cooperation results of the non-halophilic bacteria and the halophilic bacteria, was drawn in bench-scale experiments. pilot-scale ... | 2005 | 16459784 |
| missing aerobic-phase nitrogen: the potential for heterotrophic reduction of autotrophically generated nitrous oxide in a sequencing batch reactor wastewater treatment system. | several biochemical pathways can induce nitrogen loss from aerated, aerobic wastewater treatment bioreactors. these pathways include "traditional" simultaneous nitrification-denitrification (snd) (i.e. autotrophic nitrification - heterotrophic denitrification), autotrophic denitrification, and anaerobic ammonia oxidation. an oxygen limitation, often expressed in terms of low dissolved oxygen (do) concentration, is a common element of these pathways. the presented research investigated the effect ... | 2005 | 16128383 |
| comparison of nitrification performance and microbial community between submerged membrane bioreactor and conventional activated sludge system. | a submerged membrane bioreactor (smbr) and a conventional activated sludge system (cas) were compared in parallel over a period of more than 260 days on treating synthetic ammonia-bearing inorganic wastewater without sludge purge under decreased hydraulic retention times (hrts). conversion of nh4(+)-n to no3(-)-n was achieved with an efficiency of over 98% at an hrt > or = 10 h in the smbr, while similar performance was obtained at an hrt > or = 20 h in the cas. denaturing gradient gel electroph ... | 2005 | 16003978 |
| using a compact combined constructed wetland system to treat agricultural wastewater with high nitrogen. | the objectives of this study were to find appropriate conditions for nitrogen removal by a compact combined constructed wetland system and to evaluate the removal rate constant in a tropical climate. this study will present suitable operating conditions for a combined system to treat pig farm wastewater containing high ammonia-nitrogen. four laboratory-scale combined constructed wetland units (0.5 x 1.0 x 1.0 m3): vertical flow vegetated bed over horizontal flow sand bed, were operated under an ... | 2005 | 16042242 |
| identification of acyl-homoserine lactone signal molecules produced by nitrosomonas europaea strain schmidt. | nitrosomonas europaea strain schmidt produces at least three acyl homoserine lactone (ahl) signal molecules: c(6)-homoserine lactone (hsl), c(8)-hsl, and c(10)-hsl. these compounds were identified in extracts of chemostat culture effluent by three independent methods. the concentrations of ahl in effluent were low (0.4 to 2.2 nm) but within the range known to induce ahl-responsive systems. the absence of luxi and luxm homologs from the genome of n. europaea strain schmidt suggested that ahl synt ... | 2005 | 16085894 |
| in situ substrate conversion and assimilation by nitrifying bacteria in a model biofilm. | local nitrification and carbon assimilation activities were studied in situ in a model biofilm to investigate carbon yields and contribution of distinct populations to these activities. immobilized microcolonies (related to nitrosomonas europaea/eutropha, nitrosomonas oligotropha, nitrospira sp., and to other bacteria) were incubated with [14c]-bicarbonate under different experimental conditions. nitrifying activity was measured concomitantly with microsensors (oxygen, ammonium, nitrite, nitrate ... | 2005 | 16104862 |
| structure and sequence conservation of hao cluster genes of autotrophic ammonia-oxidizing bacteria: evidence for their evolutionary history. | comparison of the organization and sequence of the hao (hydroxylamine oxidoreductase) gene clusters from the gammaproteobacterial autotrophic ammonia-oxidizing bacterium (aaob) nitrosococcus oceani and the betaproteobacterial aaob nitrosospira multiformis and nitrosomonas europaea revealed a highly conserved gene cluster encoding the following proteins: hao, hydroxylamine oxidoreductase; orf2, a putative protein; cyca, cytochrome c(554); and cycb, cytochrome c(m)(552). the deduced protein sequen ... | 2005 | 16151127 |
| loss of diversity of ammonia-oxidizing bacteria correlates with increasing salinity in an estuary system. | ammonia-oxidizing bacteria (aob) play an important role in nitrogen cycling in estuaries, but little is known about aob diversity, distribution and activity in relation to the chemical and physical changes encountered in estuary systems. although estuarine salinity gradients are well recognized to influence microbial community structure, few studies have examined the influence of varying salinity on the diversity and stability of aob populations. to investigate these relationships, we collected ... | 2005 | 16104852 |
| novel nirk cluster genes in nitrosomonas europaea are required for nirk-dependent tolerance to nitrite. | nitrite reductase (nirk) of nitrosomonas europaea confers tolerance to nitrite (no2-). the nirk gene is clustered with three genes of unknown physiological function: ncgabc. at present, this organization is unique to nitrifying bacteria. here we report that the ncgabc gene products facilitate nirk-dependent no2- tolerance by reversing the negative physiological effect that is associated with the activity of nirk in their absence. we hypothesize that the ncg gene products are involved in the deto ... | 2005 | 16166549 |
| toxin-antitoxin loci are highly abundant in free-living but lost from host-associated prokaryotes. | prokaryotic chromosomes code for toxin-antitoxin (ta) loci, often in multiple copies. in e.coli, experimental evidence indicates that ta loci are stress-response elements that help cells survive unfavorable growth conditions. the first gene in a ta operon codes for an antitoxin that combines with and neutralizes a regulatory 'toxin', encoded by the second gene. rele and mazf toxins are regulators of translation that cleave mrna and function, in interplay with tmrna, in quality control of gene ex ... | 2005 | 15718296 |
| emergence of competitive dominant ammonia-oxidizing bacterial populations in a full-scale industrial wastewater treatment plant. | 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. | 2005 | 15691975 |
| redox properties of wild-type and heme-binding loop mutants of bacterial cytochromes c measured by direct electrochemistry. | we have used protein film voltammetry (pfv) to determine the midpoint potentials of the pseudomonas aeruginosa, hydrogenobacter thermophilus, and nitrosomonas europaea wild-type monoheme cytochromes c (cyts c; pa, ht, and ne, respectively), as well as pa n64q, ht q64n, and ne v65delta mutants, as a function of ph, and buffer conditions. recent studies have suggested that the identity of the 64 position of the heme-binding loop (either asn or gln) strongly influences the conformation of the met l ... | 2005 | 16296855 |
| dna microarray detection of nitrifying bacterial 16s rrna in wastewater treatment plant samples. | a small scale dna microarray containing a set of oligonucleotide probes targeting the 16s rrnas of several groups of nitrifying bacteria was developed for the monitoring of wastewater treatment plant samples. the microarray was tested using reference rrnas from pure cultures of nitrifying bacteria. characterization of samples collected from an industrial wastewater treatment facility demonstrated that nitrifying bacteria could be detected directly by microarray hybridization without the need for ... | 2005 | 16009395 |
| para-chlorophenol inhibition on cod, nitrogen and phosphate removal from synthetic wastewater in a sequencing batch reactor. | cod, nitrogen, phosphate and para-chlorophenol (4-chlorophenol, 4-cp) removal from synthetic wastewater was investigated using a four-step sequencing batch reactor (sbr) at different sludge ages and initial para-chlorophenol (4-cp) concentrations. the nutrient removal process consisted of anaerobic, oxic, anoxic and oxic phases with hydraulic residence times (hrt) of 1/3/1/1 h and a settling phase of 0.75 h. a box-wilson statistical experiment design was used considering the sludge age (5-25 day ... | 2005 | 16023572 |
| heme axial methionine fluxion in pseudomonas aeruginosa asn64gln cytochrome c551. | heme axial methionine ligands in ferricytochromes c552 from hydrogenobacter thermophilus (ht) and nitrosomonas europaea, both members of the cyt c8 family, display fluxional behavior. the ligand motion, proposed to be inversion at sulfur, results in an unusually small range of hyperfine shifts for heme substituents in these proteins. herein, heme axial met fluxion is induced in a structurally homologous cytochrome c551 from pseudomonas aeruginosa (pa) by substituting heme pocket residue asn64 wi ... | 2005 | 16271000 |
| effect of salinity on temporal and spatial dynamics of ammonia-oxidising bacteria from intertidal freshwater sediment. | temporal and spatial dynamics within an ammonia-oxidising community from intertidal, freshwater sediments were studied in microcosms simulating flooding twice a day with fresh, brackish and marine waters. the microcosms had been filled with the upper 5 cm of intertidal freshwater sediment from the river scheldt. changes in community composition were examined by denaturing gradient gel electrophoresis of amplified dna from the community. in the first week of incubation the initially present membe ... | 2005 | 16329955 |
| a new soluble 10kda monoheme cytochrome c-552 from the anammox bacterium candidatus "kuenenia stuttgartiensis". | the chemolithoautotrophic anammox bacterium candidatus "kuenenia stuttgartiensis" grows anaerobically using ammonium as electron donor for nitrite reduction. more than 10% of the proteins in cell extracts of "k. stuttgartiensis" consist of c-type heme proteins. a 10kda soluble cytochrome c was purified from cell extracts using ultracentrifugation and anion exchange chromatography. the uv/vis spectrum of the reduced cytochrome showed the gamma, beta and alpha absorption maxima at 419, 522 and 552 ... | 2005 | 16216446 |
| chemolithotrophic haloalkaliphiles from soda lakes. | this paper summarizes recent data on the occurrence and properties of lithotrophic prokaryotes found in extremely alkaline, saline (soda) lakes. among the chemolithotrophs found in these lakes the obligately autotrophic sulfur-oxidizing bacteria were the dominant, most diverse group, best adapted to haloalkaline conditions. the culturable forms are represented by three new genera, thioalkalimicrobium, thioalkalivibrio and thioalkalispira in the gammaproteobacteria. among them, the genus thioalka ... | 2005 | 16329914 |
| culture-independent techniques for rapid detection of bacteria associated with loss of chloramine residual in a drinking water system. | chloramination is often the disinfection regimen of choice for extended drinking water systems. however, this process is prone to instability due to the growth of nitrifying bacteria. this is the first study to use alternative approaches for rapid investigation of chloraminated drinking water system instability in which flow cytometric cell sorting of bacteria with intact membranes (membrane-intact fraction) (baclight kit) or with active esterases (esterase-active fraction) (carboxyfluorescein d ... | 2005 | 16269672 |
| cometabolism of trihalomethanes by nitrosomonas europaea. | the ammonia-oxidizing bacterium nitrosomonas europaea (atcc 19718) was shown to degrade low concentrations (50 to 800 mug/liter) of the four trihalomethanes (trichloromethane [tcm], or chloroform; bromodichloromethane [bdcm]; dibromochloromethane [dbcm]; and tribromomethane [tbm], or bromoform) commonly found in treated drinking water. individual trihalomethane (thm) rate constants (k1thm) increased with increasing thm bromine substitution, with tbm > dbcm > bdcm > tcm (0.23, 0.20, 0.15, and 0.1 ... | 2005 | 16332776 |
| bacterial diversity in water samples from uranium wastes as demonstrated by 16s rdna and ribosomal intergenic spacer amplification retrievals. | bacterial diversity was assessed in water samples collected from several uranium mining wastes in ger many and in the united states by using 16s rdna and ribosomal intergenic spacer amplification retrievals. the results obtained using the 16s rdna retrieval showed that the samples collected from the uranium mill tailings of schlema/alberoda, germany, were predominated by nitrospina-like bacteria, whereas those from the mill tailings of shiprock, new mexico, usa, were predominated by gamma-pseudo ... | 2005 | 16333330 |
| communities of ammonia-oxidizing bacteria in activated sludge of various sewage treatment plants in tokyo. | 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 t ... | 2005 | 16332320 |
| high levels of nitrifying bacteria in intermittently aerated reactors treating high ammonia wastewater. | changes in the fractions of ammonia-oxidizing bacteria and nitrite-oxidizing bacteria in two laboratory-scale reactors were investigated using 16s rrna probe hybridizations. the reactors were operated in intermittent aeration mode and different aeration cycles to treat anaerobically digested swine wastewater with ammonia concentrations up to 175 mg nh(3)-n/l. high ammonia removals (>98.8%) were achieved even with increased nitrogen loads and lower aeration: non-aeration time ratios of 1h:3h. nit ... | 2005 | 16332337 |
| effects of aeration cycles on nitrifying bacterial populations and nitrogen removal in intermittently aerated reactors. | the effects of the lengths of aeration and nonaeration periods on nitrogen removal and the nitrifying bacterial community structure were assessed in intermittently aerated (ia) reactors treating digested swine wastewater. five ia reactors were operated in parallel with different aeration-to-nonaeration time ratios (ana). populations of ammonia-oxidizing bacteria (aob) and nitrite-oxidizing bacteria (nob) were monitored using 16s rrna slot blot hybridizations. aob species diversity was assessed u ... | 2005 | 16332848 |
| moderately thermophilic nitrifying bacteria from a hot spring of the baikal rift zone. | samples from three hot springs (alla, seya and garga) located in the northeastern part of baikal rift zone (buryat republic, russia) were screened for the presence of thermophilic nitrifying bacteria. enrichment cultures were obtained solely from the garga spring characterized by slightly alkaline water (ph 7.9) and an outlet temperature of 75 degrees c. the enrichment cultures of the ammonia- and nitrite oxidizers grew at temperature ranges of 27-55 and 40-60 degrees c, respectively. the temper ... | 2005 | 16332328 |
| community survey of ammonia-oxidizing bacteria in full-scale activated sludge processes with different solids retention time. | to study the effects of different solids retention time (srt) on the nitrification activity and community composition of ammonia-oxidizing bacteria (aob) in two full-scale activated sludge processes during a 5-month period. | 2005 | 16108805 |
| links between ammonia oxidizer species composition, functional diversity and nitrification kinetics in grassland soils. | 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 ... | 2005 | 15819850 |
| failure of the ammonia oxidation process in two pharmaceutical wastewater treatment plants is linked to shifts in the bacterial communities. | to investigate whether two different wastewater treatment plants (wwtps) -- treating the same pharmaceutical influent -- select for a different bacterial and/or ammonia oxidizing bacterial (aob) community. | 2005 | 16238731 |
| dissimilatory metabolism of nitrogen oxides in bacteria: comparative reconstruction of transcriptional networks. | bacterial response to nitric oxide (no) is of major importance since no is an obligatory intermediate of the nitrogen cycle. transcriptional regulation of the dissimilatory nitric oxides metabolism in bacteria is diverse and involves fnr-like transcription factors hcpr, dnr, and nnrr; two-component systems narxl and narqp; no-responsive activator norr; and nitrite-sensitive repressor nsrr. using comparative genomics approaches, we predict dna-binding motifs for these transcriptional factors and ... | 2005 | 16261196 |
| a rapid and simple respirometric biosensor with immobilized cells of nitrosomonas europaea for detecting inhibitors of ammonia oxidation. | as obligate chemolithotrophs, ammonia-oxidizing bacteria (aob) grow very slowly and are known to be extremely sensitive to a wide variety of inhibitors. since it is generally accepted that inhibition of ammonia oxidation by aob results in a total failure of nitrogen removal, it is necessary to develop a method to detect inhibitors of ammonia oxidation in wastewater. since ammonia oxidation accompanies oxygen consumption, ammonia oxidation can be easily evaluated by measuring oxygen consumption r ... | 2005 | 15681195 |
| comparative analysis of nitrifying bacteria in full-scale oxidation ditch and aerated nitrification biofilter by using fluorescent in situ hybridization (fish) and denaturing gradient gel electrophoresis (dgge). | in this study, nitrification performances and composition of nitrifying populations in a full-scale oxidation ditch and a high-rate submerged media nitrification biofilter were comparatively analyzed. in addition to different reactor configurations, effects of differing operational conditions on the nitrification efficiency and bacterial diversity were also explored and evaluated thoroughly. in microbial analysis of sludge samples fluorescent in situ hybridization (fish) and denaturing gradient ... | 2005 | 15887565 |
| laser photoinitiated nitrosylation of 3-electron reduced nm europaea hydroxylamine oxidoreductase: kinetic and thermodynamic properties of the nitrosylated enzyme. | hydroxylamine-cytochrome c554 oxidoreductase (hao) catalyzes the 4-e(-) oxidation of nh(2)oh to no(2)(-) by cytochrome c554. the electrons are transferred from nh(2)oh to a 5-coordinate heme known as p(460), the active site of hao. from p(460), c-type hemes transport the electrons through the enzyme to a remote solvent-exposed c-heme, where cyt c554 reduction occurs. when 3-60 microm no* are photogenerated by laser flash photolysis of n,n'-bis-(carboxymethyl)-n,n'-dinitroso-1,4-phenylenediamine, ... | 2005 | 15651867 |
| bacterial community shift along a subsurface geothermal water stream in a japanese gold mine. | change of bacterial community occurring along a hot water stream in the hishikari gold mine, japan, was investigated by applying a combination of various culture-independent techniques. the stream, which is derived from a subsurface anaerobic aquifer containing plentiful co2, ch4, h2, and nh4+, emerges in a mine tunnel 320 m below the surface providing nutrients for a lush microbial community that extends to a distance of approximately 7 m in the absence of sunlight-irradiation. over this distan ... | 2005 | 15776216 |
| spectroscopic and density functional studies of the red copper site in nitrosocyanin: role of the protein in determining active site geometric and electronic structure. | the electronic structure of the red copper site in nitrosocyanin is defined relative to that of the well understood blue copper site of plastocyanin by using low-temperature absorption, circular dichroism, magnetic circular dichroism, resonance raman, epr and x-ray absorption spectroscopies, combined with dft calculations. these studies indicate that the principal electronic structure change in the red copper site is the sigma rather than the pi donor interaction of the cysteine sulfur with the ... | 2005 | 15755175 |
| competition and coexistence of aerobic ammonium- and nitrite-oxidizing bacteria at low oxygen concentrations. | in natural and man-made ecosystems nitrifying bacteria experience frequent exposure to oxygen-limited conditions and thus have to compete for oxygen. in several reactor systems (retentostat, chemostat and sequencing batch reactors) it was possible to establish co-cultures of aerobic ammonium- and nitrite-oxidizing bacteria at very low oxygen concentrations (2-8 microm) provided that ammonium was the limiting n compound. when ammonia was in excess of oxygen, the nitrite-oxidizing bacteria were wa ... | 2005 | 15818474 |
| primers containing universal bases reduce multiple amoa gene specific dgge band patterns when analysing the diversity of beta-ammonia oxidizers in the environment. | the gene encoding the active site of the ammonia monooxygenase (amoa) has been exploited as molecular marker for studying ammonia-oxidizing bacteria (aob) diversity in the environment. primers amplifying functional genes are often degenerated and therefore produce multiple band patterns, when analysed with the denaturing gradient gel electrophoresis (dgge) approach. to improve the dgge band patterns we have designed new primer sets which contain inosine residues and are specific for the amoa gen ... | 2006 | 16343671 |
| nitrification performance and microbial community dynamics in a submerged membrane bioreactor with complete sludge retention. | a submerged membrane bioreactor (mbr) supplied with inorganic ammonium-bearing wastewater (nh(4)(+)-n, 500 mgl(-1)) was operated for 260 days without sludge purge under decreased hydraulic retention times (hrt) through six steps (from 30 to 5h). almost complete nitrification was obtained at a volumetric loading rate (vlr)1.2g nh(4)(+)-nl(-1)day(-1). the sludge nitrification activities were evaluated at each stage. the specific ammonium oxidizing rate (saor) decreased from the initial 0.45 to 0.1 ... | 2006 | 16310272 |
| research on leachate recirculation from different types of landfills. | landfills can produce a great amount of leachate containing highly concentrated organic matter. this is especially true for the initial leachate from landfilled municipal solid wastes (msw) that generally has concentrations of cod(cr) and bod(5) up to 80,000 and 50,000mg/l, respectively. the leachate could be disposed by means of recirculating technique, which decomposes the organics through the action of proliferating microorganisms and thereby purifies the leachate, and simultaneously accelera ... | 2006 | 16321514 |
| simulation modeling for nitrogen removal and experimental estimation of mass fractions of microbial groups in single-sludge system. | nitrification-denitrification in a single-sludge nitrogen removal system (ssnrs; with a sufficient carbon source for denitrification) was performed. with an increase in the mixed liquor recycle ratio (r(m)) from 1 to 2, the total nitrogen (tn) removal efficiency at a lower volumetric loading rate (vlr=0.21 nh(4)(+)-n m(-3) d(-1)) increased, but the tn removal efficiency at a higher vlr (0.35 kg nh(4)(+)-n m(-3) d(-1)) decreased. a kinetic model that accounts for the mass fractions of nitrosomona ... | 2006 | 15936800 |
| effect of temperature and free ammonia on nitrification and nitrite accumulation in landfill leachate and analysis of its nitrifying bacterial community by fish. | the cause of seasonal failure of a nitrifying municipal landfill leachate treatment plant utilizing a fixed biofilm was investigated by wastewater analyses and batch respirometric tests at every treatment stage. nitrification of the leachate treatment plant was severely affected by the seasonal temperature variation. high free ammonia (nh3-n) inhibited not only nitrite oxidizing bacteria (nob) but also ammonia oxidizing bacteria (aob). in addition, high ph also increased free ammonia concentrati ... | 2006 | 15927463 |
| improved methods for the cultivation of the chemolithoautotrophic bacterium nitrosomonas europaea. | the chemolithoautotrophic nitrifier nitrosomonas europaea is useful for biotechnological processes such as bioremediation of toxic chemicals, as well as playing an essential role in the global nitrogen cycle. to successfully apply this bacterium in biotechnology, large quantities of active cells need to be produced. in this paper we demonstrate improved methods for mass cultivation of n. europaea. a doubling in the final cell density to 30 mg dry wt l(-1) was achieved with a fed-batch culture te ... | 2006 | 16085327 |
| long-term monitoring of the succession of a microbial community in activated sludge from a circulation flush toilet as a closed system. | the microbial diversity and community succession of a circulation flush toilet were investigated by terminal restriction fragment length polymorphism and cloning analyses. clonal libraries of 16s rrna gene on day 3 and day 127 were constructed. on day 3, 102 clones were sequenced; proteobacteria and bacteroidetes accounted for 27% and 45%, respectively. on day 127, proteobacteria had increased to 43% and bacteroidetes had decreased to 26% of a total of 100 clones. terminal restriction fragment l ... | 2006 | 16466385 |
| distinguishing nitrous oxide production from nitrification and denitrification on the basis of isotopomer abundances. | the intramolecular distribution of nitrogen isotopes in n2o is an emerging tool for defining the relative importance of microbial sources of this greenhouse gas. the application of intramolecular isotopic distributions to evaluate the origins of n2o, however, requires a foundation in laboratory experiments in which individual production pathways can be isolated. here we evaluate the site preferences of n2o produced during hydroxylamine oxidation by ammonia oxidizers and by a methanotroph, ammoni ... | 2006 | 16391101 |
| long term effects of salt on activity, population structure and floc characteristics in enriched bacterial cultures of nitrifiers. | the effect of salinity on the activity, the composition of nitrifiers and floc characteristics of nitrifying sludge was studied. non-adapted and adapted (to 10g nacl-cl(-)/l for one year) enriched cultures of nitrifiers were tested in three sequencing batch reactors. salt was increased gradually with 5 up to 40 g cl(-)/l. no difference in steady state activity was observed between the adapted and non-adapted sludge. the activities of ammonia and nitrite oxidizers dropped 36% and 11%, respectivel ... | 2006 | 16530803 |
| tgge analysis of the diversity of ammonia-oxidizing and denitrifying bacteria in submerged filter biofilms for the treatment of urban wastewater. | the spatial and temporal diversity of the bacterial community-forming biofilms in a pilot-scale submerged biofilter used for the treatment of urban wastewater was analyzed by a temperature-gradient gel electrophoresis (tgge) approach. tgge profiles based on partial sequence of the 16s rrna gene showed that the community composition of the biofilms remained fairly stable along the column system and during the whole time of operation of the biofilter (more than 1 year). community-profiling based o ... | 2006 | 16391923 |
| changes in the community structure and activity of betaproteobacterial ammonia-oxidizing sediment bacteria along a freshwater-marine gradient. | to determine whether the distribution of estuarine ammonia-oxidizing bacteria (aob) was influenced by salinity, the community structure of betaproteobacterial ammonia oxidizers (aob) was characterized along a salinity gradient in sediments of the ythan estuary, on the east coast of scotland, uk, by denaturant gradient gel electrophoresis (dgge), cloning and sequencing of 16s rrna gene fragments. ammonia-oxidizing bacteria communities at sampling sites with strongest marine influence were dominat ... | 2006 | 16584480 |
| immunocytochemical localization of membrane-bound ammonia monooxygenase in cells of ammonia oxidizing bacteria. | the intracellular location of the membrane-bound ammonia monooxygenase (amo) in all genera of ammonia oxidizing bacteria (nitrosomonas, nitrosococcus and nitrosospira) was determined by electron microscopic immunocytochemistry. polyclonal antibodies recognizing the two subunits, amoa- and amob-proteins, were used for post-embedding labeling. ultrathin sections revealed that the amob-protein was located in all genera on the cytoplasmic membrane. in cells of nitrosomonas and nitrosococus additiona ... | 2006 | 16395553 |
| transcriptome of a nitrosomonas europaea mutant with a disrupted nitrite reductase gene (nirk). | global gene expression was compared between the nitrosomonas europaea wild type and a nitrite reductase-deficient mutant using a genomic microarray. forty-one genes were differentially regulated between the wild type and the nirk mutant, including the nirk operon, genes for cytochrome c oxidase, and seven iron uptake genes. relationships of differentially regulated genes to the nirk mutant phenotype are discussed. | 2006 | 16751567 |
| disruption of suca, which encodes the e1 subunit of alpha-ketoglutarate dehydrogenase, affects the survival of nitrosomonas europaea in stationary phase. | although nitrosomonas europaea lacks measurable alpha-ketoglutarate dehydrogenase activity, the recent completion of the genome sequence revealed the presence of the genes encoding the enzyme. a knockout mutation was created in the suca gene encoding the e1 subunit. compared to wild-type cells, the mutant strain showed an accelerated loss of ammonia monooxygenase and hydroxylamine oxidoreductase activities upon entering stationary phase. in addition, unlike wild-type cells, the mutant strain sho ... | 2006 | 16352852 |
| development and calibration of a nitrification pde model based on experimental data issued from biofilter treating drinking water. | to remove ammonia for production of drinking water, nitrification can be performed in a bio-filter. at least 1 month is necessary to capture from the groundwater and then grow a sufficient amount of nitrifying bacteria to reach the desired removal efficiency. improving start-up of bio-filters at low substrate concentration is therefore a major challenge. in this connection, it is important to develop appropriate models for designing, monitoring or analysing biofilm systems during start-up or fol ... | 2006 | 16598794 |
| characterization and quantification of ammonia-oxidizing bacteria in eutrophic coastal marine sediments using polyphasic molecular approaches and immunofluorescence staining. | tokyo bay, a eutrophic bay in japan, receives nutrients from wastewater plants and other urban diffuse sources via river input. a transect was conducted along a line from the arakawa river into tokyo bay to investigate the ecological relationship between the river outflow and the distribution, abundance and population structure of ammonia-oxidizing bacteria (aob). five surficial marine sediments were collected and analysed with polyphasic approaches. heterogeneity and genetic diversity of beta-a ... | 2006 | 16623737 |
| role of nitrogen oxides in the metabolism of ammonia-oxidizing bacteria. | ammonia-oxidizing bacteria (aob) can use oxygen and nitrite as electron acceptors. nitrite reduction by nitrosomonas is observed under three conditions: (i) hydrogen-dependent denitrification, (ii) anoxic ammonia oxidation with nitrogen dioxide (no(2)) and (iii) no(x)-induced aerobic ammonia oxidation. no(x) molecules play an important role in the conversion of ammonia and nitrite by aob. absence of nitric oxide (no), which is generally detectable during ammonia oxidation, severely impairs ammon ... | 2006 | 16417515 |
| nitrosospira spp. can produce nitrous oxide via a nitrifier denitrification pathway. | nitrous oxide (n(2)o) emission from soils is a major contributor to the atmospheric loading of this potent greenhouse gas. it is thought that autotrophic ammonia oxidizing bacteria (aob) are a significant source of soil-derived n(2)o and a denitrification pathway (i.e. reduction of no(2) (-) to no and n(2)o), so-called nitrifier denitrification, has been demonstrated as a n(2)o production mechanism in nitrosomonas europaea. it is thought that nitrosospira spp. are the dominant aob in soil, but l ... | 2006 | 16423010 |
| the yjeb (nsrr) gene of escherichia coli encodes a nitric oxide-sensitive transcriptional regulator. | microarray studies of the escherichia coli response to nitric oxide and nitrosative stress have suggested that additional transcriptional regulators of this response remain to be characterized. we identify here the product of the yjeb gene as a negative regulator of the transcription of the ytfe, hmpa and ygba genes, all of which are known to be upregulated by nitrosative stress. transcriptional fusions to the promoters of these genes were expressed constitutively in a yjeb mutant, indicating th ... | 2006 | 16428390 |
| community structures and activities of nitrifying and denitrifying bacteria in industrial wastewater-treating biofilms. | the bacterial community structure, in situ spatial distributions and activities of nitrifying and denitrifying bacteria in biofilms treating industrial wastewater were investigated by combination of the 16s rrna gene clone analysis, fluorescence in situ hybridization (fish) and microelectrodes. these results were compared with the nitrogen removal capacity of the industrial wastewater treatment plant (iwtp). both nitrification and denitrification occurred in the primary denitrification (pd) tank ... | 2006 | 16477661 |
| classification of proteins based on minimal modular repeats: lessons from nature in protein design. | proteins containing internal repeats within their primary sequence have received increased attention recently, as the extent of their presence in various organisms is recognized more fully, and their role in evolution is more thoroughly studied. presented here is a technique used to detect and classify proteins based on a modular evolutionary phenomenon that results in a series of small internal repeats. the parameters chosen are based on a minimum segment of seven residues that result in simple ... | 2006 | 16512661 |
| transcript profiles of nitrosomonas europaea during growth and upon deprivation of ammonia and carbonate. | the transcriptome of nitrosomonas europaea was analyzed with whole-genome microarrays. growing cells were compared to cells deprived of (nh4)2so4 and na2co3. hybridization signals were detected for 76% of the genes represented on the array under either or both conditions. transcript levels for 68% of the genes were at least twofold higher in growing cells than in deprived cells, while only 0.42% of the genes were present at more than twofold higher levels in deprived cells. transcript levels for ... | 2006 | 16553835 |
| abundance and population structure of ammonia-oxidizing bacteria that inhabit canal sediments receiving effluents from municipal wastewater treatment plants. | a polyphasic, culture-independent study was conducted to investigate the abundance and population structure of ammonia-oxidizing bacteria (aob) in canal sediments receiving wastewater discharge. the abundance of aob ranged from 0.2 to 1.9% and 1.6 to 5.7% of the total bacterial fraction by real-time pcr and immunofluorescence staining, respectively. clone analysis and restriction endonuclease analysis revealed that the aob communities influenced by the wastewater discharge were dominated by nitr ... | 2006 | 17021242 |
| no reductase activity of the tetraheme cytochrome c554 of nitrosomonas europaea. | the tetraheme cytochrome c(554) (cyt c(554)) from nitrosomonas europaea is believed to function as an electron-transfer protein from hydroxylamine oxidoreductase (hao). we show here that cyt c(554) also has significant no reductase activity. the protein contains one high-spin and three low-spin c-type hemes. hao catalyzed reduction of the cyt c(554), ligand binding, intermolecular electron transfer, and kinetics of no reduction by cyt c(554) have been investigated. we detect the formation of a n ... | 2006 | 16569009 |
| development and application of real-time pcr for quantification of specific ammonia-oxidizing bacteria in activated sludge of sewage treatment systems. | in this study, four real-time polymerase chain reaction (pcr) primer sets were developed for the 16s rrna genes of specific ammonia-oxidizing bacteria (aob) found in activated sludge of sewage treatment systems. the primer sets target two of several sequence types of the nitrosomonas oligotropha cluster, members within the nitrosomonas communis cluster, and all members of the nitrosomonas europaea-nitrosococcus mobilis cluster. the detection limit of each primer set was in the range of 3x10(1)-6 ... | 2006 | 16523283 |
| expression, purification, crystallization and preliminary x-ray diffraction of a novel nitrosomonas europaea cytochrome, cytochrome p460. | cytochrome p460 from nitrosomonas europaea, a novel mono-heme protein containing an unusual cross-link between a conserved lysine and the porphyrin ring, has been recombinantly expressed and purified from escherichia coli. the protein crystallizes readily and diffraction to 1.7 angstroms has been obtained in-house. the crystals belong to the trigonal space group p3(1/2)21, with unit-cell parameters a = b = 53.3, c = 127.1 angstroms, and contain one monomer in the asymmetric unit. | 2006 | 16582494 |
| sequencing batch membrane biofilm reactor for simultaneous nitrogen and phosphorus removal: novel application of membrane-aerated biofilm. | a sequencing batch membrane biofilm reactor (sbmbfr) was developed for simultaneous carbon, nitrogen, and phosphorus removal from wastewater. this reactor was composed of two functional parts: (1) a gas-permeable membrane on which a nitrifying biofilm formed and (2) a bulk solution in which bacteria, mainly denitrifying polyphosphate-accumulating organisms (dnpaos), were suspended. the reactor was operated sequentially under anaerobic condition and then under membrane aeration condition in one c ... | 2006 | 16673420 |
| nitrogen removal rates at a technical-scale pilot plant with the one-stage partial nitritation/anammox process. | traditional nitrification/denitrification is not suitable for nitrogen removal when wastewater contains high concentrations of ammonium nitrogen and low concentrations of biodegradable carbon. recently, a deammonification process was developed and proposed as a new technology for treatment of such streams. this process relies on a stable interaction between aerobic bacteria nitrosomonas, that accomplish partial nitritation and anaerobic bacteria planctomycetales, which conduct the anammox reacti ... | 2006 | 17163030 |
| the combined toxic effects of nonpolar narcotic chemicals to pseudokirchneriella subcapitata. | this paper presents the toxicity data of 10 nonpolar narcotic chemicals on pseudokirchneriella subcapitata (green algae) assessed by a new algal toxicity testing technique conducted under air-tight environment. based on do production, median effective concentration (ec50) varies from 1.73 mg/l (1-octanol) to 8,040 mg/l (2-propanol). the endpoint of algal growth rate reveals similar sensitivity as that from do production. compared to literature data, pseudokirchneriella subcapitata and nitrosomon ... | 2006 | 16687162 |
| low-temperature epr and mössbauer spectroscopy of two cytochromes with his-met axial coordination exhibiting hals signals. | c-type cytochromes with histidine-methionine (his-met) iron coordination play important roles in electron-transfer reactions and in enzymes. low-temperature electron paramagnetic resonance (epr) spectra of low-spin ferric cytochromes c can be divided into two groups, depending on the spread of g values: the normal rhombic ones with small g anisotropy and g(max) below 3.2, and those featuring large g anisotropy with g(max) between 3.3 and 3.8, also denoted as highly axial low spin (hals) species. ... | 2006 | 16688708 |
| quantitative structure-activity relationships for toxicity of nonpolar narcotic chemicals to pseudokirchneriella subcapitata. | this study presents data for 27 nonpolar narcotic compounds regarding toxicity to pseudokirchneriella subcapitata as evaluated using a closed-system algal toxicity test with an exposure time of 48 h. two test endpoints, dissolved oxygen production and algal growth rate, were used to assess the toxicity of nonpolar narcotic chemicals on algae. hydrophobicity (1-octanol-water partition coefficient [k(ow)]) provided satisfactory descriptions for the toxicity of nonpolar narcotic compounds, and quan ... | 2006 | 17089715 |
| the expanded bed biofilter: combined nitrification, solids destruction, and removal of bacteria. | developed for tertiary nitrification, this biofilter also removed carbonaceous bod (cbod) and (ss). because the biofilter is expanded, it cannot clog, and therefore does not require backflushing; yet, it removed a significant proportion of the influent ss. this unanticipated capability was due to the activities of heterotrophic bacteria, protozoa, and metazoa (nematode and oligochaete worms). the expanded bed is an intensified process, which is based on natural immobilization of microbes to smal ... | 2006 | 17163011 |
| study on performance of granular anammox process and characterization of the microbial community in sludge. | anaerobic ammonium oxidation (anammox) is a novel biological nitrogen removal process, which is regarded as the most economical process at present. in this paper, two lab-scale uasb reactors, one of which was inoculated with the mixture of anaerobic sludge and aerobic sludge, the other with river sediments, were started up, using the inorganic synthetic water containing ammonium and nitrite as influent. after 421 days' and 356 days operation respectively, the ammonium removal efficiencies in two ... | 2006 | 17163029 |
| biosensor-based control of nitrification inhibitor in municipal wastewater treatment plants. | the effect of potassium cyanide (kcn) on nitrification processes in municipal wastewater treatment plants was studied by batch nitrification tests, which indicated that nitrification processes tend to be inhibited at a lower kcn concentration than the present discharge standard to sewerage. the experiment of the biosensor using nitrifying bacteria was also conducted for continuous monitoring of nitrification inhibitor in influent wastewater, and demonstrated that the biosensor can detect kcn at ... | 2006 | 16722087 |
| stoichiometric and kinetic characterisation of nitrosomonas sp. in mixed culture by decoupling the growth and energy generation processes. | a novel method that relies on the decoupling of the energy production and biosynthesis processes was used to characterise the maintenance, cell lysis and growth processes of nitrosomonas sp. a nitrosomonas culture was enriched in a sequencing batch reactor (sbr) with ammonium as the sole energy source. fluorescent in situ hybridization (fish) showed that nitrosomonas bound to the neu probe constituted 82% of the bacterial population, while no other known ammonium or nitrite oxidizing bacteria we ... | 2006 | 16723160 |
| solution structure of acyl carrier protein from nitrosomonas europaea. | 2006 | 16741959 | |
| nitrification in a biofilm at low ph values: role of in situ microenvironments and acid tolerance. | the sensitivity of nitrifying bacteria to acidic conditions is a well-known phenomenon and generally attributed to the lack and/or toxicity of substrates (nh3 and hno2) with decreasing phs. in contrast, we observed strong nitrification at a ph around 4 in biofilms grown on chalk particles and investigated the following hypotheses: the presence of less acidic microenvironments and/or the existence of acid-tolerant nitrifiers. microelectrode measurements (in situ and under various experimental con ... | 2006 | 16751543 |
| real-time quantitative lamp (loop-mediated isothermal amplification of dna) as a simple method for monitoring ammonia-oxidizing bacteria. | loop-mediated isothermal amplification (lamp) of dna is a novel technique for the amplification of dna under isothermal conditions. for the first time, we applied this method to develop a simple and quantitative monitoring method for environmental microorganisms targeting amoa gene in ammonia-oxidizing bacteria. quantitative analysis was performed first by measuring fluorescence derived from an intercalation dye using a real-time thermal cycler, and then by measuring the turbidity of the reactio ... | 2006 | 16790287 |
| iron nutrition and physiological responses to iron stress in nitrosomonas europaea. | nitrosomonas europaea, as an ammonia-oxidizing bacterium, has a high fe requirement and has 90 genes dedicated to fe acquisition. under fe-limiting conditions (0.2 microm fe), n. europaea was able to assimilate up to 70% of the available fe in the medium even though it is unable to produce siderophores. addition of exogenous siderophores to fe-limited medium increased growth (final cell mass). fe-limited cells had lower heme and cellular fe contents, reduced membrane layers, and lower nh3- and n ... | 2006 | 16802173 |
| [enhanced ammonia removal and microbial community structure analysis using bacterial quinone profile in itfb]. | water quality during the start-up period was changed in order to enhance the later nitrifying ability of the internal-circulation three-phase bio-fluidized bed (itfb). the experimental results showed that high n/c ratio and low feeding concentration of cod were two key conditions for enhancing the ammonia removal. after the enhanced start-up, an efficient removal efficiency of both cod and ammonia was achieved with hrt 2h when treating sanitary wastewater, the average ammonia removal rate was 74 ... | 2006 | 16881325 |
| quantification of ammonia-oxidizing bacteria populations in full-scale sewage activated sludge systems and assessment of system variables affecting their performance. | this study carried out quantification of ammonia-oxidizing bacteria (aob) populations in 12 full-scale sewage activated sludge systems that were different in ammonia removals and treatment processes during three different seasons. experiment was divided into 3 parts: 1) analysis of aob communities by pcr-dgge-cloning-sequencing of 16s rrna genes; 2) development of four real-time pcr primer sets for quantification of the particular aob of interest; and 3) quantification of aob populations by usin ... | 2006 | 16898141 |
| microbial community development in a laboratory-scale nitrifying activated sludge system with input from a side-stream bioreactor treating digester supernatant. | three laboratory-scale activated sludge treatment trains were operated to investigate the effect on biodiversity in plug flow (pfr) main-stream sewage treatment from input of biomass from side-stream reactors treating anaerobic digester supernatant. one train had a completely mixed (cstr) side-stream reactor, one a pfr side-stream reactor, and the third train was a control that did not receive input from a side-stream reactor. restriction endonucleases were used to digest polymerase chain reacti ... | 2006 | 16898154 |
| transcriptional analysis of the multicopy hao gene coding for hydroxylamine oxidoreductase in nitrosomonas sp. strain eni-11. | the nitrifying bacterium nitrosomonas sp. strain eni-11 has three copies of the gene encoding hydroxylamine oxidoreductase (hao(1), hao(2), and hao(3)) on its genome. broad-host-range reporter plasmids containing transcriptional fusion genes between hao copies and lacz were constructed to analyze the expression of each hydroxylamine oxidoreductase gene (hao) copy individually and quantitatively. beta-galactosidase assays of eni-11 harboring reporter plasmids revealed that all hao copies were tra ... | 2006 | 16926500 |
| post-treatment of a slaughterhouse wastewater: stability of the microbial community of a sequencing batch reactor operated under oxygen limited conditions. | slaughterhouse wastewater is a complex effluent with an important content of organic nitrogen. after an anaerobic treatment where most of the organic matter is removed, the nitrogen, remains as ammonium and post-treatment of the effluent is necessary. sequencing batch reactor (sbr) technology has been developed to completely remove nitrogen in one single reactor combining aerobic and anoxic stages. under oxygen limited conditions only nitrite is produced with concomitant energy saving. the stabi ... | 2006 | 16939105 |
| strategies of aerobic ammonia-oxidizing bacteria for coping with nutrient and oxygen fluctuations. | in most natural environments as well as in engineered environments, such as wastewater treatment plants, ammonia-oxidizing bacteria (aob) experience fluctuating substrate concentrations. several physiological traits, such as low maintenance energy demand and decay rate, cell-to-cell communication, cell mobility, stable enzymes and rnas, could allow aob to maintain themselves under unfavourable circumstances. this review examines whether aob possess such traits and how these traits might offer ad ... | 2006 | 16958903 |