| dynamic response of nitrifying activated sludge batch culture to increased chloride concentration. | dynamic response of nitrifying activated sludge batch cultures to increased chloride concentration was studied in this paper, which focused upon the changes in the specific nitrification rate (snr) and nitrifier population when the chloride level was gradually or stepwise increased to 30,000 mg cl l-1. the dominant species of ammonia-oxidizers and nitriteoxidizers in the population were examined by fluorescent in situ hybridization technique with 16s rrna-targeted oligonucleotide probes. it was ... | 2003 | 14509699 |
| a comparitive study of ammonia-oxidizing bacteria in lab-scale industrial wastewater treatment reactors. | the diversity and community structure of the beta-proteobacterial ammonia oxidising bacteria (aob) in a range of different lab-scale industrial wastewater treatment reactors were compared. three of the reactors treat waste from mixed domestic and industrial sources whereas the other reactor treats waste solely of industrial origin. pcr with aob selective primers was combined with denaturing gradient ge electrophoresis to allow comparative analysis of the dominant aob populations and the phylogen ... | 2003 | 14518850 |
| molecular analysis of microbial communities in nitrification and denitrification reactors treating high ammonia leachate. | molecular analysis of microbial populations in two bench-scale nitrification and denitrification reactors fed with high ammonia landfill leachate was conducted in this study by using dgge, cloning, and fish techniques in addition to classical efficiency control parameters. nitrification tank was operated with a computer-controlled alkalinity dosing system to supply the alkalinity intermittently as consumed on the basis of on-line ph monitoring. by keeping the ph at 7.0 with this system, 99% nitr ... | 2003 | 14524656 |
| the isotope array, a new tool that employs substrate-mediated labeling of rrna for determination of microbial community structure and function. | a new microarray method, the isotope array approach, for identifying microorganisms which consume a (14)c-labeled substrate within complex microbial communities was developed. experiments were performed with a small microarray consisting of oligonucleotide probes targeting the 16s rrna of ammonia-oxidizing bacteria (aob). total rna was extracted from a pure culture of nitrosomonas eutropha grown in the presence of [(14)c]bicarbonate. after fluorescence labeling of the rna and microarray hybridiz ... | 2003 | 14602652 |
| characterization of nitrifying granules produced in an aerobic upflow fluidized bed reactor. | since nitrification is the rate-determining step in the biological nitrogen removal from wastewater, many research studies have been conducted on the immobilization of nitrifying bacteria. in this research, granulation of nitrifying bacteria in an aerobic upflow fluidized bed (aufb) reactor in a nitrification process for inorganic wastewater containing 500 g/m(3) of nh(4)(+)-n was investigated. it was observed that spherical, pseudocubic and elliptical granules with a diameter of 346 microm were ... | 2003 | 14604643 |
| chemolithoorganotrophic growth of nitrosomonas europaea on fructose. | the nitrifying bacterium nitrosomonas europaea can obtain all its carbon for growth from co(2) and all its energy and reductant for growth from the oxidation of nh(3) and is considered an obligate chemolithoautotroph. previous studies have shown that n. europaea can utilize limited amounts of certain organic compounds, including amino acids, pyruvate, and acetate, although no organic compound has been reported to support the growth of n. europaea. the recently completed genomic sequence of n. eu ... | 2003 | 14617645 |
| nitrification and nitrifying bacteria in the lower seine river and estuary (france). | the achères wastewater treatment plant, located just downstream of paris, discharges its effluents into the lower seine river. the effluents contain large numbers of heterotrophic bacteria, organic matter, and ammonium and are a source of nitrifying bacteria. as a result, degradation of organic matter by heterotrophic bacteria and subsequent oxygen depletion occur immediately downstream of the effluent outlet, whereas nitrifying bacteria apparently need to build up a significant biomass before a ... | 2003 | 14660353 |
| metabolism of inorganic n compounds by ammonia-oxidizing bacteria. | ammonia oxidizing bacteria extract energy for growth from the oxidation of ammonia to nitrite. ammonia monooxygenase, which initiates ammonia oxidation, remains enigmatic given the lack of purified preparations. genetic and biochemical studies support a model for the enzyme consisting of three subunits and metal centers of copper and iron. knowledge of hydroxylamine oxidoreductase, which oxidizes hydroxylamine formed by ammonia monooxygenase to nitrite, is informed by a crystal structure and det ... | 2003 | 14695127 |
| analysis of size distribution and areal cell density of ammonia-oxidizing bacterial microcolonies in relation to substrate microprofiles in biofilms. | a fine-scale in situ spatial organization of ammonia-oxidizing bacteria (aob) in biofilms was investigated by combining molecular techniques (i.e., fluorescence in situ hybridization (fish) and 16s rdna-cloning analysis) and microelectrode measurements. important parameters of aob microcolonies such as size distribution and areal cell density of the microcolonies were determined and correlated with substrate microprofiles in the biofilms. in situ hybridization with a nested 16s rrna-targeted oli ... | 2004 | 14705015 |
| comparative analysis of genetic diversity and expression of amoa in wastewater treatment processes. | the genetic diversity and expression of amoa of autotrophic ammonia oxidizers in wastewater treatment processes were investigated by rt-pcr and denaturing gradient gel electrophoresis (dgge) in order to identify active components of ammonia-oxidizer populations in a such processes. ammonia oxidizers, evidenced by the presence of amoa mrna, were regarded as metabolically active. the dgge profiles derived from amoa mrna and from its gene, which were amplified by rt-pcr or pcr using samples collect ... | 2004 | 14758520 |
| inhibition of membrane-bound methane monooxygenase and ammonia monooxygenase by diphenyliodonium: implications for electron transfer. | diphenyliodonium (dpi) is known to irreversibly inactivate flavoproteins. we have found that dpi inhibits both membrane-bound methane monooxygenase (pmmo) from methylococcus capsulatus and ammonia monooxygenase (amo) of nitrosomonas europaea. the effect of dpi on nadh-dependent pmmo activity in vitro is ascribed to inactivation of ndh-2, a flavoprotein which we proposed catalyzes reduction of the quinone pool by nadh. dpi is a potent inhibitor of type 2 nadh:quinone oxidoreductase (ndh-2), with ... | 2004 | 14761987 |
| isolation of nitrifying organisms and oxygen supply. | | 1952 | 14947885 |
| a distinctive electrocatalytic response from the cytochrome c peroxidase of nitrosomonas europaea. | here the cytochrome c peroxidase (ccp) from nitrosomonas europaea is examined using the technique of catalytic protein film voltammetry. submonolayers of the bacterial diheme enzyme at a pyrolytic graphite edge electrode give catalytic, reductive signals in the presence of the substrate hydrogen peroxide. the resulting waveshapes indicate that ccp is bound non-covalently in a highly active configuration. the native enzyme has been shown to possess two heme groups of low and high potential (l and ... | 2004 | 14973133 |
| influence of soil moisture on linear alkylbenzene sulfonate-induced toxicity in ammonia-oxidizing bacteria. | moisture affects bioavailability and fate of pollutants in soil, but very little is known about moisture-induced effects on pollutant toxicity. we here report on a modifying effect of moisture on degradation of linear alkylbenzene sulfonates (lass) and on their toxicity towards ammonia-oxidizing bacteria (aob) in agricultural soil. in soil spiked with two las levels (250 or 1,000 mg/kg) and incubated at four different moisture levels (9-100% of water-holding capacity), degradation was strongly a ... | 2004 | 14982383 |
| genera-specific immunofluorescence labeling of ammonia oxidizers with polyclonal antibodies recognizing both subunits of the ammonia monooxygenase. | polyclonal antibodies that recognize the two subunits amoa and amob of the ammonia monooxygenase (amo) were applied to identify ammonia-oxidizing bacteria by immunofluorescence (if) labeling in pure, mixed, and enriched cultures. the antibodies against the amoa were produced using a synthetic peptide of the amoa of nitrosomonas eutropha, whereas the antibodies against the amob had been developed previously is against the whole b-subunit of the amo [pinck et al. (2001) appl environ microbiol 67:1 ... | 2004 | 14994172 |
| start-up of autotrophic nitrogen removal reactors via sequential biocatalyst addition. | a procedure for start-up of oxygen-limited autotrophic nitrification-denitrification (oland) in a lab-scale rotating biological contactor (rbc) is presented. in this one-step process, nh4+ is directly converted to n2 without the need for an organic carbon source. the approach is based on a sequential addition of two types of easily available biocatalyst to the reactor during start-up: aerobic nitrifying and anaerobic, granular methanogenic sludge. the first is added as a source of aerobic ammoni ... | 2004 | 14998042 |
| use of amob as a new molecular marker for ammonia-oxidizing bacteria. | specific molecular determination and classification of ammonia-oxidizing bacteria have relied on the use of conventional markers such as 16s rdna. however, this gene does not satisfactorily provide a wide vision of all phylogenetic lineages. despite the initial expectations, the use of functional genes as for example amoa has only been useful to corroborate the established taxonomy. ammonia-oxidizing bacteria constitute a physiological group that crosses over principal phylogenetic radiations. t ... | 2004 | 15003690 |
| physiologic and proteomic evidence for a role of nitric oxide in biofilm formation by nitrosomonas europaea and other ammonia oxidizers. | no, a free radical gas, is the signal for nitrosomonas europaea cells to switch between different growth modes. at an no concentration of more than 30 ppm, biofilm formation by n. europaea was induced. no concentrations below 5 ppm led to a reversal of the biofilm formation, and the numbers of motile and planktonic (motile-planktonic) cells increased. in a proteomics approach, the proteins expressed by n. europaea were identified. comparison studies of the protein patterns of motile-planktonic a ... | 2004 | 15090520 |
| an analysis of nitrification during the aerobic digestion of secondary sludges. | investigations were undertaken to study the occurrence and progress of nitrification during aerobic digestion of activated sludge in a wide range of initial concentrations of total solids (1000 to 80 000 mg litre(-1), initial ph range of 4.5 to 10.4 and digestion temperature range of 5 degrees to 60 degrees c. batch aerobic digestion studies on activated sludge grown on wastewater (enriched with organic solids from human excretal material) indicate that almost complete elimination of the 'biodeg ... | 1989 | 15092439 |
| ammonium and hydroxylamine uptake and accumulation in nitrosomonas. | starved cells of nitrosomonas europaea and further ammonia oxidizers were able to rapidly accumulate ammonium and hydroxylamine to an internal concentration of about 1 and 0.8 m, respectively. in kinetic studies, the uptake/accumulation rates for ammonium [3.1 mmol (g protein)(-1) min(-1)] and hydroxylamine [4.39 mmol (g protein)(-1) min(-1)] were determined. the uptake and accumulation process of ammonium and hydroxylamine was not coupled to ammonia or hydroxylamine oxidation and nitrite was no ... | 2004 | 15133102 |
| 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 |
| application of a fine thread beam to the structure analysis of a hemihedrally twinned crystal of hydroxylamine oxidoreductase. | accurate diffraction intensity data have been collected from a twinned p6(3) crystal of the 24-haem protein hydroxylamine oxidoreductase, from a nitrifying chemoautotrophic bacterium nitrosomonas europaea, using synchrotron radiation at station bl6a of the photon factory. estimation of the twinning fraction and deconvoluted intensity data, including native and heavy-atom derivative data, gave an improved patterson function. four diffraction data sets were collected from one crystal and an estima ... | 1998 | 15263716 |
| evaluating the effect of dissolved oxygen on ammonia-oxidizing bacterial communities in activated sludge. | the effect of dissolved oxygen (do) on the communities of ammonia-oxidizing bacteria (aob) in activated sludge was evaluated in lab-scale and full-scale reactors using the amoa gene as the basis for phylogenetic comparisons. under controlled laboratory conditions, two chemostats seeded with activated sludge from the same source were operated with high-do (8.5 mg/l) and low-do (0.24 and 0.12 mg/l) concentrations for a period of 300 days. at the end of the operation period, the chemostats had enri ... | 2004 | 15276744 |
| effects of hydroxylamine on microbial community structure and function of autotrophic nitrifying biofilms determined by in situ hybridization and the use of microelectrodes. | effects of hydroxylamine (nh2oh), an intermediate of nh4+ oxidation, on microbial community structure and function of two autotrophic nitrifying biofilms fed with and without nh2oh were analyzed by a 16s rrna approach and the use of microelectrodes. in the nh2oh-added biofilm, partial oxidation of nh4+ to no2- was observed, whereas complete oxidation of nh4+ to no3- was achieved in the control biofilm. in situ hybridization results revealed that no nitrite-oxidizing bacteria (nob) hybridized wit ... | 2004 | 15303724 |
| high nitrification rate at low ph in a fluidized bed reactor with chalk as the biofilm carrier. | a typical steady state bulk ph of about 5 was established in a nitrifying fluidized bed with chalk as the only buffer agent. in spite of the low ph, high rate nitrification was observed with the nitrification kinetic parameters in the chalk reactor similar to those of biological reactors operating at ph>7. various methods were used to determine the reasons for high rate nitrification at such low ph including (i) determination of bacterial species, (ii) microsensor measurements in the biofilm, an ... | 2004 | 15303729 |
| effect of solid hold-up on nitrite accumulation in a biofilm reactor--molecular characterization of nitrifying communities. | biological ammonium oxidation was carried out in two inverse turbulent bed reactors fed with synthetic mineral wastewater containing a high ammonium concentration (100 mg n-nh4+/l). both reactors were started-up and operated in the same conditions except for the solid carrier concentration: the solid hold-up ratios applied, defined as the ratios of static to expanded bed height, were 0.1 and 0.3 in reactors r10 and r30 respectively. these two solid hold-up ratios generate different particle-to-p ... | 2004 | 15303732 |
| a two-stage sbr process for removal of organic substrate and nitrogen via nitrite-type nitrification-denitrification. | a two-stage sbr process (tssbr) was applied for the treatment of wastewater with high strength cod and nitrogen. most of organic substrate was removed in the first stage sbr reactor (sbr1) under the aerobic condition. subsequently the second stage sbr reactor (sbr2) firstly was operated under the aerobic condition for simultaneous nitrite-type nitrification and removal of a small amount of residual organic substrate. nitrification was controlled to the nitrite-type nitrification. then denitrific ... | 2004 | 15332681 |
| removal of carbonaceous and nitrogenous pollutants from a synthetic wastewater using a membrane-coupled bioreactor. | two modified ludzack-ettinger (mle)-type membrane-coupled bioreactors (mbrs) were investigated in this study for the purpose of removing both nitrogenous and carbonaceous pollutants from a synthetic wastewater. during the first mbr experiment, removal efficiencies were high (>90%) for chemical oxygen demand (cod) and ammonia, but total nitrogenous pollutant removal efficiency was poor (approximately 25%). bacterial community analysis of ammonia oxidizing bacteria (aob) by a nested pcr-dgge appro ... | 2004 | 15338423 |
| characterization of a small metal binding protein from nitrosomonas europaea. | a small metal-binding protein (smbp) with no known similarity to other proteins in current databases was isolated and characterized from the periplasm of nitrosomonas europaea. the primary structure of this small (9.9 kda) monomeric protein is characterized by a series of 10 repeats of a seven amino acid motif and an unusually high number of histidine residues. the protein was isolated from n. europaea with cu(ii) bound but was found to be capable of binding multiple equivalents of a variety of ... | 2004 | 15366930 |
| the isolation of nitrosomonas europaea in pure culture. | | 1950 | 15415571 |
| effect of organic compounds on nitrosomonas. | | 1950 | 15423583 |
| a challenge for 21st century molecular biology and biochemistry: what are the causes of obligate autotrophy and methanotrophy? | we assess the use to which bioinformatics in the form of bacterial genome sequences, functional gene probes and the protein sequence databases can be applied to hypotheses about obligate autotrophy in eubacteria. obligate methanotrophy and obligate autotrophy among the chemo- and photo-lithotrophic bacteria lack satisfactory explanation a century or more after their discovery. various causes of these phenomena have been suggested, which we review in the light of the information currently availab ... | 2004 | 15449607 |
| 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 |
| dynamics of a pasture soil microbial community after deposition of cattle urine amended with [13c]urea. | within grazed pastures, urine patches are hot spots of nitrogen turnover, since dietary n surpluses are excreted mainly as urea in the urine. this short-term experiment investigated 13c uptake in microbial lipids after simulated deposition of cattle urine at 10.0 and 17.1 g of urea c m(-2). confined field plots without or with cattle urine amendment were sampled after 4 and 14 days, and soil from 0- to 5-cm and 10- to 20-cm depths was analyzed for content and composition of phospholipid fatty ac ... | 2004 | 15528493 |
| high-rate nitrification at low ph in suspended- and attached-biomass reactors. | this article reports on high-rate nitrification at low ph in biofilm and suspended-biomass reactors by known chemolithotrophic bacteria. in the biofilm reactor, at low ph (4.3 +/- 0.1) and low bulk ammonium concentrations (9.3 +/- 3.3 mg.liter(-1)), a very high nitrification rate of 5.6 g of n oxidized.liter(-1).day(-1) was achieved. the specific nitrification rate (0.55 g of n.g of biomass(-1).day(-1)) was similar to values reported for nitrifying reactors at optimal ph. in the suspended-biomas ... | 2004 | 15528509 |
| denaturing gradient gel electrophoretic analysis of ammonia-oxidizing bacterial community structure in the lower seine river: impact of paris wastewater effluents. | the seine river is strongly affected by the effluents from the acheres wastewater treatment plant (wwtp) downstream of the city of paris. we have shown that the effluents introduce large amounts of ammonia and inoculate the receiving medium with nitrifying bacteria. the aim of the present study was to investigate the diversity of the ammonia-oxidizing bacterial population by identifying autochthonous bacteria from upstream and/or allochthonous ammonia-oxidizing bacteria from the wwtp effluents. ... | 2004 | 15528539 |
| 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 |
| occurrence of nitrifiers and diversity of ammonia-oxidizing bacteria in developing drinking water biofilms. | we studied the population dynamics of nitrifying bacteria during the development of biofilms up to 233 or 280 days on polyvinylchloride pipes connected to two full-scale drinking water distribution networks supplying processed and chloraminated surface water. the numbers of nitrifiers in biofilms were enumerated at intervals of 10-64 days by the most probable number (mpn) method at waterworks and at several study sites in distribution network areas. the numbers of nitrifiers increased towards th ... | 2004 | 15556217 |
| 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 |
| distribution of ammonia-oxidizing bacteria in sewage activated sludge: analysis based on 16s rdna sequence. | this study carried out analysis of ammonia-oxidizing bacteria (aob) communities in 12 sewage activated sludge systems standing in eight sewage treatment plants located in tokyo. the systems were different in the treatment process configuration: anaerobic/anoxic/aerobic (a20), anaerobic/aerobic (ao), and conventional activated sludge (as) processes. aob communities were analyzed by sequences of 16s rdna amplicons, which were separated by denaturing gradient gel eletrophoresis (dgge) after specifi ... | 2004 | 15566181 |
| folding, conformational changes, and dynamics of cytochromes c probed by nmr spectroscopy. | nmr spectroscopy has become a vital tool for studies of protein conformational changes and dynamics. oxidized fe(iii)cytochromes c are a particularly attractive target for nmr analysis because their paramagnetism (s = (1)/(2)) leads to high (1)h chemical shift dispersion, even for unfolded or otherwise disordered states. in addition, analysis of shifts induced by the hyperfine interaction reveals details of the structure of the heme and its ligands for native and nonnative protein conformational ... | 2004 | 15578827 |
| denitrification and ammonia oxidation by nitrosomonas europaea wild-type, and nirk- and norb-deficient mutants. | the phenotypes of three different nitrosomonas europaea strains--wild-type, nitrite reductase (nirk)-deficient and nitric oxide reductase (norb)-deficient strains--were characterized in chemostat cell cultures, and the effect of nitric oxide (no) on metabolic activities was evaluated. all strains revealed similar aerobic ammonia oxidation activities, but the growth rates and yields of the knock-out mutants were significantly reduced. dinitrogen (n2) was the main gaseous product of the wild-type, ... | 2004 | 15583163 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| regulatory analysis of the nitrosomonas europaea grpe-dnak-dnaj operon. | the complete nucleotide sequences of the nitrosomonas europaea grpe and dnaj genes were determined. transcriptional analysis showed that grpe was transcribed as polycistronic transcripts with the dnak and dnaj from a sigma(32)-dependent heat-inducible promoter located upstream of grpe. this promoter had significantly less activity than one located upstream of dnak. | 1999 | 16232457 |
| development of chitosan-magnetite aggregates containing nitrosomonas europaea cells for nitrification enhancement. | a cell suspension of the nitrifying bacterium nitrosomonas europaea obtained after 96-h cultivation was subjected to magnetic separation using chitosan-conjugated magnetite particles (chitosan-magnetite), which have the ability to form aggregates with microbial cells. an equilibrium condition was obtained at room temperature after 30 min and over 90% of the cells were recovered when the chitosan-magnetite concentration was 200 mg/l. the relationship between the cell concentration in the supernat ... | 2000 | 16232771 |
| ribulose-1,5-bisphosphate carboxylase/oxygenase from an ammonia-oxidizing bacterium, nitrosomonas sp. k1: purification and properties. | the ammonia-oxidizing chemoautotrophic nitrosomonas sp. strain k1 exhibited marked ribulose-1,5-bisphosphate carboxylase (rubisco) activity. the rubisco [ec 4.1.1.39] was purified as an electrophoretically homogeneous protein. the molecular mass of the enzyme was estimated to be about 460 kda by gel filtration, and it consists of two subunits [large (l): 52.2 kda; small (s): 13.3 kda] as demonstrated by sds-page. this confirmed that the enzyme has an l(8)s(8) structure. the k(m) values of the en ... | 2000 | 16232884 |
| effect of oxygen concentration on nitrogen removal by nitrosomonas europaea and paracoccus denitrificans immobilized within tubular polymeric gel. | tubular gel reactors containing nitrosomonas europaea and paracoccus denitrificans, which remove nitrogen from solutions through a process of nitrification and denitrification, require oxygen for ammonia oxidation, the first and rate-limiting step in the process. to accelerate ammonia oxidation, high concentrations of oxygen were applied to the reactors instead of air. although a 50% o2:n2 gas mixture and pure oxygen were both toxic to free n. europaea cells, they actually accelerated ammonia ox ... | 2000 | 16232927 |
| purification and comparison of triosephosphate isomerases from ammonia-oxidizing bacteria isolated from terrestrial and marine environments. | triosephosphate isomerases [tims, ec 5.3.1.1] were purified from two ammonia-oxidizing bacteria: nitrosomonas sp. k1 (k1), nitrosomonas sp. tno632 (tno). the molecular masses of the native enzymes were estimated to be about 53.6 (k1-tim) and 51.9 kda (tno-tim) by gel filtration, whereas sds-page produced one band for each enzyme with m(r) values of 27.1 (k1-tim) and 26.4 kda (tno-tim), respectively, suggesting that the enzymes consist of identical subunits. the apparent k(m) for d-glyceraldehyde ... | 2001 | 16233048 |
| two kinds of ammonia-oxidizing bacteria isolated from biologically deodorizing plants in cold district. | two kinds of ammonia-oxidizing bacteria isolated from biologically deodorizing plants in cold districts in japan were identified as nitrosomonas sp. iwt202 and nitrosomonas sp. iwt514. the optimum phs for growth were 8.0 (iwt202) and 7.5 (iwt514). although rockwool samples for isolation were collected from the same plants, the optimum temperature for growth of strain iwt202 (37 degrees c) differed from that of strain iwt514 (30 degrees c). the bacteria had a higher (iwt202, 37 degrees c) and low ... | 2004 | 16233691 |
| 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 |
| 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 |
| 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 |
| 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 |
| [preliminary study of characteristics of a special nitrosomonas]. | a special obligately-autotrophic nitrosomonas was isolated from high temperature and hypersaline drainage water obtained off a wastewater treatment plant. it was gram-negative, nonsporulating, ellipsoidal or short-rod shaped bacterium that singly arranged or arranged in a circle or in a row. cells were 0.7 to 0.9 microm wide and 1.2 to 1.98 microm long. electron-microscopic scanning of these cells indicated that they were wrapped by unknown fluff-like matter. they oxidized ammonium to nitrite an ... | 2003 | 16276877 |
| [study on the ammonia-oxidizing bacteria from activated sludge samples by the molecular analysis]. | the molecular analysis methods of pcr amplification, random cloning and sequencing were used to investigate the ammonia-oxidizing bacterial community composition and the activity of ammonia-monooxygenase (amo) from the activated sludge samples of an industrial wastewater treatment plant receiving sewage with high ammonia concentration. it is the first time to use pcr-dgge combined technique to analysis the difference of dominant bacterial community compositions of the activated sludge samples in ... | 2003 | 16279205 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |