Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
|---|
| differential regulation of amoa and amob gene copies in nitrosomonas europaea. | nitrosomonas europaea contains two nearly identical copies of the operon, amocab, which encodes the ammonia monooxygenase (amo) enzyme. cells of n. europaea containing single mutations in either amoa or amob gene copies were incubated in ammonium both prior to and after exposure to acetylene or light. for each strain, the o(2) consumption rates and amounts of amoa polypeptide, the active site-containing subunit of amo, produced in each strain were determined. strains carrying a mutation in eithe ... | 2000 | 11064189 |
| phylogeny of all recognized species of ammonia oxidizers based on comparative 16s rrna and amoa sequence analysis: implications for molecular diversity surveys. | the current perception of evolutionary relationships and the natural diversity of ammonia-oxidizing bacteria (aob) is mainly based on comparative sequence analyses of their genes encoding the 16s rrna and the active site polypeptide of the ammonia monooxygenase (amoa). however, only partial 16s rrna sequences are available for many aob species and most aob have not yet been analyzed on the amoa level. in this study, the 16s rdna sequence data of 10 nitrosomonas species and nitrosococcus mobilis ... | 2000 | 11097916 |
| effects of agronomic treatments on structure and function of ammonia-oxidizing communities. | the aim of this study was to determine the effects of different agricultural treatments and plant communities on the diversity of ammonia oxidizer populations in soil. denaturing gradient gel electrophoresis (dgge), coupled with specific oligonucleotide probing, was used to analyze 16s rrna genes of ammonia oxidizers belonging to the beta subgroup of the division proteobacteria by use of dna extracted from cultivated, successional, and native deciduous forest soils. community profiles of the dif ... | 2000 | 11097922 |
| a survey of 16s rrna and amoa genes related to autotrophic ammonia-oxidizing bacteria of the beta-subdivision of the class proteobacteria in contaminated groundwater. | in this study, we investigated the size and structure of autotrophic ammonia oxidizer (aao) communities in the groundwater of a contamination plume originating from a mill-tailings disposal site. the site has high levels of dissolved n from anthropogenic sources, and exhibited wide variations in the concentrations of no3- and nh3 + nh4+. community structures were examined by pcr-dgge targeting 16s rdna with band excision and sequence analysis, and by analysis of amoa fragment clone libraries. aa ... | 2000 | 11109489 |
| polyclonal antibodies recognizing the amob protein of ammonia oxidizers of the beta-subclass of the class proteobacteria. | a 41-kda protein of nitrosomonas eutropha was purified, and the n-terminal amino acid sequence was found to be nearly identical with the sequence of amob, a subunit of ammonia monooxygenase. this protein was used to develop polyclonal antibodies, which were highly specific for the detection of the four genera of ammonia oxidizers of the beta-subclass of proteobacteria (nitrosomonas, including nitrosococcus mobilis, which belongs phylogenetically to nitrosomonas; nitrosospira; nitrosolobus; and n ... | 2001 | 11133435 |
| energy model and metabolic flux analysis for autotrophic nitrifiers. | the behavior of pure cultures of nitrifying microorganisms under autotrophic growth operating conditions was investigated and the relations between their energy metabolism and their anabolism analyzed by means of metabolic network computation. the description of the metabolism of the nitrifiers is extended to their energy metabolism by introducing compartmentalization (cytoplasmic and periplasmic sides) and studying coupling between the electron transport chain and the proton gradient generation ... | 2001 | 11180062 |
| transcript analysis of multiple copies of amo (encoding ammonia monooxygenase) and hao (encoding hydroxylamine oxidoreductase) in nitrosomonas europaea. | the genes encoding ammonia monooxygenase (amocab), hydroxylamine oxidoreductase (hao), and the c-type cytochrome c-554 (hcy) are present in multiple copies in the genome of nitrosomonas europaea. the upstream regions of the two copies of amoc, the three copies of hao, and one copy of hcy were cloned and sequenced. primer extension reactions were done to identify transcription start sites for these genes, as well as for amoa. putative sigma(70) promoter sequences were found associated with all bu ... | 2001 | 11208810 |
| the evolutionary history of chromosomal super-integrons provides an ancestry for multiresistant integrons. | integrons are genetic elements that acquire and exchange exogenous dna, known as gene cassettes, by a site-specific recombination mechanism. characterized gene cassettes consist of a target recombination sequence (attc site) usually associated with a single open reading frame coding for an antibiotic resistance determinant. the affiliation of multiresistant integrons (mris), which contain various combinations of antibiotic resistance gene cassettes, with transferable elements underlies the rapid ... | 2001 | 11209061 |
| microenvironments and distribution of nitrifying bacteria in a membrane-bound biofilm. | the distribution of nitrifying bacteria of the genera nitrosomonas, nitrosospira, nitrobacter and nitrospira was investigated in a membrane-bound biofilm system with opposed supply of oxygen and ammonium. gradients of oxygen, ph, nitrite and nitrate were determined by means of microsensors while the nitrifying populations along these gradients were identified and quantified using fluorescence in situ hybridization (fish) in combination with confocal laser scanning microscopy. the oxic part of th ... | 2000 | 11214800 |
| development of nitrification inhibition assays using pure cultures of nitrosomonas and nitrobacter. | restricted requirements for nitrogen reduction at wastewater treatment plants have increased the need for assays determining the inhibition of nitrification. in this paper, two new assays studying ammonia oxidation and nitrite oxidation, respectively, are presented. as test organisms, pure cultures of nitrosomonas and nitrobacter isolated from activated sludge are used. the assays are performed in test tubes where the bacteria are incubated with the compound or wastewater to be tested. the nitri ... | 2001 | 11228996 |
| community structure and activity dynamics of nitrifying bacteria in a phosphate-removing biofilm. | the microbial community structure and activity dynamics of a phosphate-removing biofilm from a sequencing batch biofilm reactor were investigated with special focus on the nitrifying community. o(2), no(2)(-), and no(3)(-) profiles in the biofilm were measured with microsensors at various times during the nonaerated-aerated reactor cycle. in the aeration period, nitrification was oxygen limited and restricted to the first 200 microm at the biofilm surface. additionally, a delayed onset of nitrif ... | 2001 | 11229931 |
| differential inhibition in vivo of ammonia monooxygenase, soluble methane monooxygenase and membrane-associated methane monoxygenase by phenylacetylene. | phenylacetylene was investigated as a differential inhibitor of ammonia monooxygenase (amo), soluble methane monooxygenase (smmo) and membrane-associated or particulate methane monooxygenase (pmmo) in vivo. at phenylacetylene concentrations > 1 microm, whole-cell amo activity in nitrosomonas europaea was completely inhibited. phenylacetylene concentrations above 100 microm inhibited more than 90% of smmo activity in methylococcus capsulatus bath and methylosinus trichosporium ob3b. in contrast, ... | 2000 | 11233157 |
| nitrification inhibitors from the roots of leucaena leucocephala. | the nitrification inhibition (ni) bioassay guided fractionation of the methanol extract of lyophilized and milled roots of leuceana leucocephala resulted in the isolation of four compounds, 1-4, as confirmed from their 1h and 13c nmr spectral data. compound 1, gallocatechin, was the most active ni inhibitor at 12 microg/ml. epigallocatechin, 2, and epicatechin, 4, isolated as mixtures, were not assayed individually for their ni inhibitory activities against the nitrification bacterium nitrosomon ... | 2000 | 11312789 |
| conversion of ammonia to dinitrogen in wastewater by nitrosomonas europaea. | because nitrosomonas europaea contains ammonia-oxidizing enzyme, nitrite reductase, and nitrous oxide reductase, the conversion of ammonia to dinitrogen was tried with different reaction conditions. in aerobic reaction conditions, ammonium was converted to nitrite (no2-), while under oxygen-limiting or oxygen-free conditions, no2(-)-n formed from ammonia oxidation by n. europaea was reduced to n2o and dinitrogen with 22% conversion. during denitrification, optimal ph for the production of n2o an ... | 2001 | 11318035 |
| dissimilatory nitrite reductase genes from autotrophic ammonia-oxidizing bacteria. | the presence of a copper-containing dissimilatory nitrite reductase gene (nirk) was discovered in several isolates of beta-subdivision ammonia-oxidizing bacteria using pcr and dna sequencing. pcr primers cunir3 and cunir4 were designed based on published nirk sequences from denitrifying bacteria and used to amplify a 540-bp fragment of the nirk gene from nitrosomonas marina and five additional isolates of ammonia-oxidizing bacteria. amplification products of the expected size were cloned and seq ... | 2001 | 11319103 |
| nitrification and denitrification as a source for no and no2 production in high-strength wastewater. | laboratory and half-technical scale experiments were performed to evaluate nitric oxide (no) and nitrogen dioxide (no2) production during biological n-elimination from wastewater with high ammonium concentration (about 700 mg n l-1). in a laboratory scale bioreactor with biomass retention, the ammonia oxidizer nitrosomonas europaea and the denitrifier paracoccus denitrificans were grown as reference organisms in co-culture in order to simulate the nitrifying and denitrifying community of wastewa ... | 2001 | 11337836 |
| nitrogen transformation during organic waste composting by the rutgers system and its effects on ph, ec and maturity of the composting mixtures. | the evolution of the different forms of nitrogen during the composting of several wastes was studied, as well as its relation to the ph, electrical conductivity and parameters of maturity of the composts obtained. four mixtures were prepared from different organic materials: sewage sludge, municipal solid waste, brewery sludge, sorghum bagasse, cotton waste and pine bark. the evolution of the different forms of nitrogen during composting depended on the material which supplied the nitrogen to th ... | 2001 | 11341692 |
| crystal structure of a novel red copper protein from nitrosomonas europaea. | nitrosocyanin (nc) is a mononuclear red copper protein isolated from the ammonia oxidizing bacterium nitrosomonas europaea. although nc exhibits some sequence homology to classic blue copper proteins, its spectroscopic and electrochemical properties are drastically different. the 1.65 a resolution crystal structure of oxidized nc reveals an unprecedented trimer of single domain cupredoxins. each copper center is partially covered by an unusual extended beta-hairpin structure from an adjacent mon ... | 2001 | 11341832 |
| high-resolution structures of the oxidized and reduced states of cytochrome c554 from nitrosomonas europaea. | cytochrome c554 (cyt c554) is a tetra-heme cytochrome involved in the oxidation of nh3 by nitrosomonas europaea. the x-ray crystal structures of both the oxidized and dithionite-reduced states of cyt c554 in a new, rhombohedral crystal form have been solved by molecular replacement, at 1.6 a and 1.8 a resolution, respectively. upon reduction, the conformation of the polypeptide chain changes between residues 175 and 179, which are adjacent to hemes iii and iv. cyt c554 displays conserved heme-pa ... | 2001 | 11372197 |
| toxic effects of linear alkylbenzene sulfonate on metabolic activity, growth rate, and microcolony formation of nitrosomonas and nitrosospira strains. | strong inhibitory effects of the anionic surfactant linear alkylbenzene sulfonate (las) on four strains of autotrophic ammonia-oxidizing bacteria (aob) are reported. two nitrosospira strains were considerably more sensitive to las than two nitrosomonas strains were. interestingly, the two nitrosospira strains showed a weak capacity to remove las from the medium. this could not be attributed to adsorption or any other known physical or chemical process, suggesting that biodegradation of las took ... | 2001 | 11375155 |
| implementation, study and calibration of a modified asm2d for the simulation of sbr processes. | an enhanced process model for sbrs has been developed. though the basic mechanism largely draws on the activated sludge model n. 2d, its new features are the splitting of the nitrification stage in a two-step process, according to the well known nitrosomonas-nitrobacter oxidation sequence, and an improved xpao dynamics, involved in the anaerobic/aerobic phosphorus removal process. the model was implemented through the dll technique allowing complied c++ modules to be linked to an ordinary simuli ... | 2001 | 11381934 |
| enhancement of nitrifying biofilm formation using selected eps produced by heterotrophic bacteria. | the possibility of enhancing nitrifying biofilm formation rate with the aid of selected eps produced by heterotrophic bacteria was investigated. when eps production characteristics were examined for four kinds of heterotrophs isolated from a domestic wastewater treatment reactor, two strains obtained from biofilms (b1, b2) exhibited a higher polysaccharide production rate than those from suspended flocs (a1, a2). among eps components, the concentration of uronic acids gave a good correlation wit ... | 2001 | 11381968 |
| effects of gaseous no2 on cells of nitrosomonas eutropha previously incapable of using ammonia as an energy source. | cells of nitrosomonas eutropha grown under anoxic conditions with hydrogen as electron donor and nitrite as electron acceptor were initially unable to oxidize ammonia (ammonium) and hydroxylamine when transferred to oxic conditions. recovery of ammonia and hydroxylamine oxidation activity was dependent on the presence of no2. under oxic conditions, without addition of no2, ammonia consumption started after 8 - 9 days, and small amounts of no and no2 were detectable in the gas atmosphere. removin ... | 2001 | 11392482 |
| in situ reverse transcription to detect the cbbl gene and visualize rubisco in chemoautotrophic nitrifying bacteria. | in situ methodologies targeting the cbbl gene were used to visualize cells of nitrifying bacteria. both procaryotic in situ pcr (is-pcr) and in situ reverse transcription (isrt) protocols were employed to determine gene presence and expression, respectively. | 2001 | 11412349 |
| (13)c incorporation into dna as a means of identifying the active components of ammonia-oxidizer populations. | to identify active co2-assimilating species of ammonia-oxidizing bacteria in fresh water sediment. | 2001 | 11412351 |
| soft particle analysis of bacterial cells and its interpretation of cell adhesion behaviors in terms of dlvo theory. | the electrokinetic properties of two nitrifying strains, nitrosomonas europaea and nitrobacter winogradskyi, and three heterotrophic bacteria, escherichia coli, pseudomonas putida and pseudomonas aeruginosa, were examined by electrophoretic mobility measurement and analyzed using the soft particle electrophoresis theory that is suitable for biological particles. the bacterial adhesion characteristics onto glass bead substratum were also evaluated by packed bed method. the mobility of the bacteri ... | 2001 | 11451661 |
| in situ analysis of nitrosomonas spp. in wastewater treatment wetland biofilms. | the presence of the ammonia-oxidising group nitrosomonas in developing biofilms from a subsurface flow dairy effluent treatment wetland was investigated using in situ hybridisation and a crude semi-quantitative pcr. fluorescently labelled oligonucleotide probes, specific for the nitrosomonas europaea and nitrosomonas eutropha species, showed that nitrifying bacteria were present from the onset of biofilm development but that over a five month period the proportions remained low (averaging less t ... | 2001 | 11456173 |
| correlations of structure and electronic properties from epr spectroscopy of hydroxylamine oxidoreductase. | hydroxylamine oxidoreductase (hao) from the autotrophic nitrifying bacterium nitrosomonas europaea catalyzes the oxidation of nh(2)oh to hno(2). the enzyme contains eight hemes per subunit which participate in catalytic function and electron transport. the structure of the enzyme shows a unique spatial arrangement of the eight hemes, subsets of which are now observed in four other proteins. the spatial arrangement displays three types of diheme pairing motifs. at least four of the eight hemes ar ... | 2001 | 11457010 |
| influence of effluent irrigation on community composition and function of ammonia-oxidizing bacteria in soil. | the effect of effluent irrigation on community composition and function of ammonia-oxidizing bacteria (aob) in soil was evaluated, using techniques of molecular biology and analytical soil chemistry. analyses were conducted on soil sampled from lysimeters and from a grapefruit orchard which had been irrigated with wastewater effluent or fertilizer-amended water (faw). specifically, comparisons of aob community composition were conducted using denaturing gradient gel electrophoresis (dgge) of pcr ... | 2001 | 11472914 |
| ammonia oxidation by nitrosomonas eutropha with no(2) as oxidant is not inhibited by acetylene. | the effect of acetylene ((14)c(2)h(2)) on aerobic and anaerobic ammonia oxidation by nitrosomonas eutropha was investigated. ammonia monooxygenase (amo) was inhibited and a 27 kda polypeptide (amoa) was labelled during aerobic ammonia oxidation. in contrast, anaerobic, no(2)-dependent ammonia oxidation (no(2)/n(2)o(4) as oxidant) was not affected by acetylene. further studies gave evidence that the inhibition as well as the labelling reaction were o(2)-dependent. cells pretreated with acetylene ... | 2001 | 11496001 |
| factors affecting nitrite build-up in nitrifying biofilm reactor. | nitrite build-up in a nitrifying biofilm reactor for direct denitrification from the nitrite stage was investigated. at least three factors were found to influence the nitrite build-up: (i) the relative specific growth rates of nitrosomonas to nitrobacter, microns/micronb in the biofilm; (ii) the relative initial ratio between nitrosomonas and nitrobacter on the support surface, (mao)ns/(mao)nb; (iii) the level of free ammonia, particularly at greater than 0.1 mg n/l that can be inhibitory to ni ... | 2001 | 11501303 |
| isolation and properties of obligately chemolithoautotrophic and extremely alkali-tolerant ammonia-oxidizing bacteria from mongolian soda lakes. | five mixed samples prepared from the surface sediments of 20 north-east mongolian soda lakes with total salt contents from 5 to 360 g/l and ph values from 9.7 to 10.5 were used to enrich for alkaliphilic ammonia-oxidizing bacteria. successful enrichments at ph 10 were achieved on carbonate mineral medium containing 0.6 m total na(+) and < or =4 mm nh(4)cl. five isolates (ans1-ans5) of ammonia-oxidizing bacteria capable of growth at ph 10 were obtained from the colonies developed on bilayered gra ... | 2001 | 11511864 |
| activity monitoring for nitrifying bacteria by fluorescence in situ hybridization and respirometry. | the activities of two families of nitrifying bacteria were measured by applied respirometer and fluorescence in situ hybridization (fish) for the purpose of monitoring nitrogen removal. oxygen uptake rates (our) for nitrosomonas and nitrobacter were separately measured with the dosing of selective inhibitors during respirometric monitoring. the fish method was applied to analyze microorganism communities. in 5 mg nh4+-n/l solution, the total nitrogen oxygen demand (nod) was found to be 6,672 mg ... | 2001 | 11516017 |
| inhibition of aerobic growth and nitrification of bacteria in sewage sludge by antibacterial agents. | toxicity of antibacterial agents on environmentally relevant bacteria was investigated using activated sludge. the growth and nitrifying inhibiting effects for activated sludge of benzyl penicillin (penicillin g) (bp), tetracycline (tc), chlortetracycline (ctc), oxytetracycline (otc), olaquindox (o), streptomycin (st), tiamulin (ti), tylosin (tyl) sulfadiazine (sdz), metronidazole (met), and oxolinic acid (oxa) was investigated. studies were performed in accordance to the iso 15522 (1999) and is ... | 2001 | 11525487 |
| a bioreactor system for the nitrogen loop in a controlled ecological life support system. | as space missions become longer in duration, the need to recycle waste into useful compounds rises dramatically. this problem can be addressed by the development of controlled ecological life support systems (celss) (i.e., engineered closed/controlled eco-systems (ecces)), consisting of human and plant modules. one of the waste streams leaving the human module is urine. in addition to the reclamation of water from urine, recovery of the nitrogen is important because it is an essential nutrien ... | 1996 | 11538973 |
| tropospheric sources of nox: lightning and biology. | laboratory experiments to quantify the global production of nox (no + no2) in the troposphere due to atmospheric lightning and biogenic activity in soil are presented. these laboratory experiments, as well as other studies, suggest that the global production of nox by lightning probably ranges between 2 and 20 mt(n)y-1 of no and is strongly dependent on the total energy deposited by lightning, a quantity not well-known. in our laboratory experiments, nitrifying micro-organisms is soil were fou ... | 1984 | 11540827 |
| vfeu water quality control in sts-95 mission. | in sts-95 space shuttle mission, an aquatic animal research facility, vestibular function experiment unit (vfeu), was flown to perform neurobiological experiment with marine fish, oyster toadfish. for this purpose, we have developed a sea water purification system using highly active nitrifying bacteria at low temperature. with this system, the water quality in the vfeu was maintained in sufficient condition to keep the toadfish in healthy state for 9 days of the mission. this report summarizes ... | 1999 | 11542797 |
| water quality management for low temperature marine fishes in space. | vestibular function experiment unit (vfeu), one of the spacelab facility flown in neurolab mission (sts-90) in april, 1998, was to support neurophysiological research using a marine fish, opsanus tau (oyster toadfish). the functions of the vfeu were primarily a quality management of environmental water during the mission at 14 degrees c and for acquiring physiological signals from implanted micro-electrodes in the otolith nerves as well as the spatial acceleration of the fish. a key element of t ... | 1999 | 11542798 |
| closed water recirculating system for fish rearing equipped with bioreactor capable of simultaneous nitrification and denitrification. | five crucian carp, carassius auratus langsdorfiicarps had been reared in a closed water recirculating system. the system was equipped with the compact bioreactor using the plate gels capable of both nitrification and denitrification in a single unit. ammonia and nitrite concentrations in the rearing water had been maintained below 0.05 mg-n/l, and nitrate concentration also controlled between 2 and 8 mg-n/l with the bioreactor. as concerns nitrogen budget in the closed system, 95.0% of nitrogen ... | 1999 | 11542800 |
| r&d of long-term life support system by using electrochemically activated biofilm reactor of aquatic animals for space examinations. | we have developed the long-term life support system that enables the experiment of aquatic animals breeding for 90 days or more for the future experiments in orbit. in order to enable long-term breeding of wide aquatic animals, it is necessary to remove nitrate produced by biological nitrification. then, we examined a denitrification method to use an electrochemical reaction of biofilm-electrode reactor. in this research, we have not kept the aquatic animals actually but imitated breeding of fiv ... | 1999 | 11542801 |
| ammonia-oxidizing bacteria: a model for molecular microbial ecology. | the eutrophication of many ecosystems in recent decades has led to an increased interest in the ecology of nitrogen transformation. chemolitho-autotrophic ammonia-oxidizing bacteria are responsible for the rate-limiting step of nitrification in a wide variety of environments, making them important in the global cycling of nitrogen. these organisms are unique in their ability to use the conversion of ammonia to nitrite as their sole energy source. because of the importance of this functional grou ... | 2001 | 11544365 |
| quantification of nitrifying bacterial populations in a full-scale nitrifying trickling filter using fluorescent in situ hybridization. | fluorescent in situ hybridization (fish) was used to quantify the ammonia-oxidizing populations within intact biofilm samples collected from a full-scale nitrifying trickling filter (ntf). ammonia, nitrite, and nitrate concentrations were measured for aqueous samples taken in conjunction with biofilm samples at multiple filter depths. correlation coefficients for individual sampling events, calculated by simple linear regression of fish signal area and ammonia removal rates, ranged from 0.558 wh ... | 2001 | 11561593 |
| effect of zinc and benzalkonium chloride on nitrosomonas communis and potential nitrification in soil. | a bacterial contact assay is described which uses a chemoautotrophic microorganism, nitrosomonas communis (strain nm2) to evaluate the biological effect of contaminated soils. the effects of two toxicants on the ammonium oxidation activity of the autochthonous microbial population in the soil are compared with inhibition of the same biological response in the new monospecies bioassay. experiments were performed using soil samples dosed with organic and inorganic contaminants (benzalkonium chlori ... | 2001 | 11594031 |
| direct detection by in situ pcr of the amoa gene in biofilm resulting from a nitrogen removal process. | ammonia oxidation is a rate-limiting step in the biological removal of nitrogen from wastewater. analysis of microbial communities possessing the amoa gene, which is a small subunit of the gene encoding ammonia monooxygenase, is important for controlling nitrogen removal. in this study, the amoa gene present in nitrosomonas europaea cells in a pure culture and biofilms in a nitrifying reactor was amplified by in situ pcr. in this procedure, fixed cells were permeabilized with lysozyme and subjec ... | 2001 | 11679354 |
| crystal structure of nitrosomonas europaea cytochrome c peroxidase and the structural basis for ligand switching in bacterial di-heme peroxidases. | the crystal structure of the fully oxidized di-heme peroxidase from nitrosomonas europaea has been solved to a resolution of 1.80 a and compared to the closely related enzyme from pseudomonas aeruginosa. both enzymes catalyze the peroxide-dependent oxidation of a protein electron donor such as cytochrome c. electrons enter the enzyme through the high-potential heme followed by electron transfer to the low-potential heme, the site of peroxide activation. both enzymes form homodimers, each of whic ... | 2001 | 11695895 |
| potential nitrification rate as a tool for screening toxicity in metal-contaminated soils. | a potential nitrification rate test (pnr) was used to identify metal toxicity in field-contaminated soils. the test was applied to metal salt-spiked soils, to 27 uncontaminated soils, and to 15 soils that are contaminated by former metal smelting activities. four agricultural soils (ph 4.5-6.6) were spiked with various rates of cdcl2 (0-200 mg cd/kg dry wt) or zncl2 (0-3,000 mg cd/kg dry wt) and were equilibrated more than nine months prior to testing. the soil zn ec50s of the pnr were between 1 ... | 2001 | 11699771 |
| identification of bacteria responsible for ammonia oxidation in freshwater aquaria. | culture enrichments and culture-independent molecular methods were employed to identify and confirm the presence of novel ammonia-oxidizing bacteria (aob) in nitrifying freshwater aquaria. reactors were seeded with biomass from freshwater nitrifying systems and enriched for aob under various conditions of ammonia concentration. surveys of cloned rrna genes from the enrichments revealed four major strains of aob which were phylogenetically related to the nitrosomonas marina cluster, the nitrososp ... | 2001 | 11722936 |
| phylogeny and functional expression of ribulose 1,5-bisphosphate carboxylase/oxygenase from the autotrophic ammonia-oxidizing bacterium nitrosospira sp. isolate 40ki. | the autotrophic ammonia-oxidizing bacteria (aob), which play an important role in the global nitrogen cycle, assimilate co(2) by using ribulose 1,5-bisphosphate carboxylase/oxygenase (rubisco). here we describe the first detailed study of rubisco (cbb) genes and proteins from the aob. the cbbls genes from nitrosospira sp. isolate 40ki were cloned and sequenced. partial sequences of the rubisco large subunit (cbbl) from 13 other aob belonging to the beta and gamma subgroups of the class proteobac ... | 2002 | 11751824 |
| validation of publication of new names and new combinations previously effectively published outside the ijsem. | 2001 | 11760931 | |
| detailed phylogeny of ammonia-oxidizing bacteria determined by rdna sequences and dna homology values. | a comparison of the phylogeny of 38 isolates of chemolithoautotrophic ammonia-oxidizing bacteria (aob) based on 16s rrna gene sequences, 16s-235 rdna intergenic spacer region (isr) sequences and species affiliations based on dna homology values was performed. the organisms studied all belong to the beta-subclass of the proteobacteria and included representatives of nitrosomonas, nitrosococcus and nitrosospira. the similarity values of the 16s rdna sequences were high, particularly within the nit ... | 2001 | 11760943 |
| grassland management regimens reduce small-scale heterogeneity and species diversity of beta-proteobacterial ammonia pxidizer populations. | the impact of soil management practices on ammonia oxidizer diversity and spatial heterogeneity was determined in improved (addition of n fertilizer), unimproved (no additions), and semi-improved (intermediate management) grassland pastures at the sourhope research station in scotland. ammonia oxidizer diversity within each grassland soil was assessed by pcr amplification of microbial community dna with both ammonia oxidizer-specific, 16s rrna gene (rdna) and functional, amoa, gene primers. pcr ... | 2002 | 11772604 |
| ammonia- and nitrite-oxidizing bacterial communities in a pilot-scale chloraminated drinking water distribution system. | nitrification in drinking water distribution systems is a common operational problem for many utilities that use chloramines for secondary disinfection. the diversity of ammonia-oxidizing bacteria (aob) and nitrite-oxidizing bacteria (nob) in the distribution systems of a pilot-scale chloraminated drinking water treatment system was characterized using terminal restriction fragment length polymorphism (t-rflp) analysis and 16s rrna gene (ribosomal dna [rdna]) cloning and sequencing. for ammonia ... | 2002 | 11772611 |
| single-base-pair discrimination of terminal mismatches by using oligonucleotide microarrays and neural network analyses. | the effects of single-base-pair near-terminal and terminal mismatches on the dissociation temperature (t(d)) and signal intensity of short dna duplexes were determined by using oligonucleotide microarrays and neural network (nn) analyses. two perfect-match probes and 29 probes having a single-base-pair mismatch at positions 1 to 5 from the 5' terminus of the probe were designed to target one of two short sequences representing 16s rrna. nonequilibrium dissociation rates (i.e., melting profiles) ... | 2002 | 11772632 |
| quantification of nitrosomonas oligotropha-like ammonia-oxidizing bacteria and nitrospira spp. from full-scale wastewater treatment plants by competitive pcr. | utilizing the principle of competitive pcr, we developed two assays to enumerate nitrosomonas oligotropha-like ammonia-oxidizing bacteria and nitrite-oxidizing bacteria belonging to the genus nitrospira: the specificities of two primer sets, which were designed for two target regions, the amoa gene and nitrospira 16s ribosomal dna (rdna), were verified by dna sequencing. both assays were optimized and applied to full-scale, activated sludge wastewater treatment plant (wwtp) samples. if it was as ... | 2002 | 11772633 |
| diversity of ammonia monooxygenase operon in autotrophic ammonia-oxidizing bacteria. | autotrophic ammonia-oxidizing bacteria use the essential enzyme ammonia monooxygenase (amo) to transform ammonia to hydroxylamine. the amo operon consists of at least three genes, amoc, amoa, and amob; amoa encodes the subunit containing the putative enzyme active site. the use of the amo genes as functional markers for ammonia-oxidizing bacteria in environmental applications requires knowledge of the diversity of the amo operon on several levels: (1) the copy number of the operon in the genome, ... | 2002 | 11807563 |
| gaseous no2 as a regulator for ammonia oxidation of nitrosomonas eutropha. | cells of nitrosomonas eutropha strain n904 that were denitrifying under anoxic conditions with hydrogen as electron donor and nitrite as electron acceptor were unable to utilize ammonium (ammonia) as an energy source. the recovery of ammonia oxidation activity was dependent on the presence of no2. anaerobic ammonia oxidation activity was observed in a helium atmosphere supplemented with 25 ppm no2 after 20 h. ammonia oxidation activity was detected after 2-3 days using an oxic atmosphere with 25 ... | 2001 | 11816974 |
| nitrosocyanin, a red cupredoxin-like protein from nitrosomonas europaea. | nitrosocyanin (nc), a soluble, red cu protein isolated from the ammonia-oxidizing autotrophic bacterium nitrosomonas europaea, is shown to be a homo-oligomer of 12 kda cu-containing monomers. oligonucleotides based on the amino acid sequence of the n-terminus and of the c-terminal tryptic peptide were used to sequence the gene by pcr. the translated protein sequence was significantly homologous with the mononuclear cupredoxins such as plastocyanin, azurin, or rusticyanin, the type 1 copper-bindi ... | 2002 | 11827513 |
| nitrite as a stimulus for ammonia-starved nitrosomonas europaea. | ammonia-starved cells of nitrosomonas europaea are able to preserve a high level of ammonia-oxidizing activity in the absence of ammonium. however, when the nitrite-oxidizing cells that form part of the natural nitrifying community do not keep pace with the ammonia-oxidizing cells, nitrite accumulates and may subsequently inhibit ammonia oxidation. the maintenance of a high ammonia-oxidizing capacity during starvation is then nullified. in this study we demonstrated that cells of n. europaea sta ... | 2002 | 11872501 |
| water purification system by using the biofilter for long-term experiment equipment with aquatic animals for the space station. | we have developed a water purification system that enables long-term experiment with aquatic animals for 90 days or more on the space station. we designed the system that combined a biofilter for ammonia removal (nitrification) with another for nitrate removal (denitrification). the experiment with goldfish was for 90 days with an aquatic animals' examination device. the equipment consists of a fish tank, a filter module, pumps, and an artificial lung for gas exchange. the goldfish were kept in ... | 1998 | 11876203 |
| the canon system (completely autotrophic nitrogen-removal over nitrite) under ammonium limitation: interaction and competition between three groups of bacteria. | the canon system (completely autotrophic nitrogen removal over nitrite) can potentially remove ammonium from wastewater in a single, oxygen-limited treatment step. the usefulness of canon as an industrial process will be determined by the ability of the system to recover from major disturbances in feed composition. the canon process relies on the stable interaction between only two bacterial populations: nitrosomonas-like aerobic and planctomycete-like anaerobic ammonium oxidising bacteria. the ... | 2001 | 11876366 |
| the ribulose-1,5-bisphosphate carboxylase/oxygenase gene cluster of methylococcus capsulatus (bath). | the genes encoding the ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) from methylococcus capsulatus (bath) were localised to an 8.3-kb ecori fragment of the genome. genes encoding the large subunit ( cbbl), small subunit ( cbbs) and putative regulatory gene ( cbbq) were shown to be located on one cluster. surprisingly, cbbo, a second putative regulatory gene, was not located in the remaining 1.2-kb downstream (3') of cbbq. however, probing of the m. capsulatus (bath) genome with cbbo ... | 2002 | 11889481 |
| spectroscopic characterization of the no adduct of hydroxylamine oxidoreductase. | hydroxylamine oxidoreductase (hao) from the autotrophic nitrifying bacterium nitrosomonas europaea catalyzes the oxidation of nh2oh to no2-. the enzyme contains eight hemes per subunit which participate in catalysis and electron transport. no is found to bind to the enzyme and inhibit electron flow to the acceptor protein, cytochrome c554. no is found to oxidize either partially or fully reduced hao, but no will not reduce ferric hao. since no can be reduced but not oxidized to product by hao, n ... | 2002 | 11926822 |
| application of toxicity monitor using nitrifying bacteria biosensor to sewerage systems. | toxic substances may be included in wastewater influent and can damage biological processing of wastewater treatment, therefore continuous toxic-monitoring of wastewater influent is needed. this paper describes the potential toxic-monitoring applications of the toxicity monitor using a nitrifying bacteria biosensor to sewerage systems. the results of sensitivity tests show that aspects of wastewater do not affect the sensor sensitivity and confirm that the sensor can be applied to wastewater mon ... | 2002 | 11936643 |
| specific layers in aerobically grown microbial granules. | to determine the optimal size of aerobically grown granules for wastewater treatment by measuring specific layers within the granules. | 2002 | 11940154 |
| nitrite reductase of nitrosomonas europaea is not essential for production of gaseous nitrogen oxides and confers tolerance to nitrite. | a gene that encodes a periplasmic copper-type nitrite reductase (nirk) was identified in nitrosomonas europaea. disruption of this gene resulted in the disappearance of nir activity in cell extracts. the nitrite tolerance of nirk-deficient cells was lower than that of wild-type cells. unexpectedly, nirk-deficient cells still produced nitric oxide (no) and nitrous oxide (n(2)o), the latter in greater amounts than that of wild-type cells. this demonstrates that nirk is not essential for the produc ... | 2002 | 11948173 |
| evolution of sucrose synthesis. | cyanobacteria and proteobacteria (purple bacteria) are the only prokaryotes known to synthesize sucrose (suc). suc-p synthase, suc-phosphatase (spp), and suc synthase activities have previously been detected in several cyanobacteria, and genes coding for suc-p synthase (sps) and suc synthase (sus) have been cloned from synechocystis sp. pcc 6803 and anabaena (nostoc) spp., respectively. an open reading frame in the synechocystis genome encodes a predicted 27-kd polypeptide that shows homology to ... | 2002 | 11950997 |
| evaluation of non-cyanobacterial genome sequences for occurrence of genes encoding proteins homologous to cyanophycin synthetase and cloning of an active cyanophycin synthetase from acinetobacter sp. strain dsm 587. | all publicly accessible microbial genome databases were searched for the occurrence of genes encoding proteins homologous to the cyanophycin synthetase (cpha) of synechocystis sp. strain pcc 6803 in order to reveal the capability of microorganisms not belonging to the cyanobacteria to synthesize cyanophycin. among 65 genome sequences, genes homologous to cpha were found in acinetobacter sp. strain adp1 (encoding a protein homologous to cpha with 40% amino acid identity), bordetella bronchiseptic ... | 2002 | 11976746 |
| distribution and activity of ammonia oxidizing bacteria in a large full-scale trickling filter. | the biofilm in a full-scale nitrifying trickling filter (ntf) treating municipal wastewater has been investigated with microbiological methods using fluorescence in situ hybridization (fish) with 16s rrna oligonucleotide probes in combination with confocal laser scanning microscopy (clsm) and mathematical modeling using a dynamic multi-species biofilm reactor model. ammonia oxidizing bacteria (aob) were found to belong to the genus nitrosomonas at different depths in the ntf at every sampling oc ... | 2002 | 11996334 |
| denaturing gradient gel electrophoresis (dgge) approaches to study the diversity of ammonia-oxidizing bacteria. | denaturing gradient gel electrophoresis (dgge) of pcr amplicons of the ammonia monooxygenase gene (amoa) was developed and employed to investigate the diversity of ammonia-oxidizing bacteria (aob) in four different habitats. the results were compared to dgge of pcr-amplified partial 16s rdna sequences made with primers specific for ammonia-oxidizing bacteria. potential problems, such as primer degeneracy and multiple gene copies of the amoa gene, were investigated to evaluate and minimize their ... | 2002 | 11997169 |
| isolation and characterization of cbbl and cbbs genes encoding form i ribulose-1,5-bisphosphate carboxylase/oxygenase large and small subunits in nitrosomonas sp. strain eni-11. | the cbbl and cbbs genes encoding form i ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) large and small subunits in the ammonia-oxidizing bacterium nitrosomonas sp. strain eni-11 were cloned and sequenced. the deduced gene products, cbbl and cbbs, had 93 and 87% identity with thiobacillus intermedius cbbl and nitrobacter winogradskyi cbbs, respectively. expression of cbbl and cbbs in escherichia coli led to the detection of rubisco activity in the presence of 0.1 mm isopropyl-beta-d-th ... | 2002 | 12005060 |
| species diversity of uncultured and cultured populations of soil and marine ammonia oxidizing bacteria. | although molecular techniques are considered to provide a more comprehensive view of species diversity of natural microbial populations, few studies have compared diversity assessed by molecular and cultivation-based approaches using the same samples. to achieve this, the diversity of natural populations of ammonia oxidising bacteria in arable soil and marine sediments was determined by analysis of 16s rdna sequences from enrichment cultures, prepared using standard methods for this group, and f ... | 2001 | 12024248 |
| intestinal urea metabolism: could the bacteria involved in nitrogen cycle lead to reutilization of intestinal urea nitrogen in uremic rabbits? | we aimed to evaluate the effect of bacteria involved in the nitrogen cycle on the reutilization of intestinal urea nitrogen in uremic rabbits. new zealand white rabbits were made uremic via bilateral nephrectomy. study and control rabbits were given live and heat-inactivated bacteria through their jejunostomies. after they were injected with 99mtc biurea intravenously, serial serum and stool levels of labeled nitrogen were assessed by instant thin-layer chromatography, and the change in the labe ... | 2002 | 12026184 |
| influence of different cultivars on populations of ammonia-oxidizing bacteria in the root environment of rice. | comparisons of the activities and diversities of ammonia-oxidizing bacteria (aob) in the root environment of different cultivars of rice (oryza sativa l.) indicated marked differences despite identical environmental conditions during growth. gross nitrification rates obtained by the 15n dilution technique were significantly higher in a modern variety, ir63087-1-17, than in two traditional varieties. phylogenetic analysis based on the ammonium monooxygenase gene (amoa) identified strains related ... | 2002 | 12039768 |
| high mortality in zebrafish (danio rerio). | a group of 100 adult zebrafish were housed in a new system at a stocking density of 20 fish per tank. four weeks after arrival, 15 fish presented with petechial hemorrhages and ulceration on the surfaces of the skin. samples of the fish were collected for histopathology, fungal culture, and bacterial culture and sensitivity. water samples were analyzed for ph, ammonia, nitrite, and submitted for bacterial and fungal culture. histologically, the epidermis had multiple areas of ulceration and mono ... | 1999 | 12086431 |
| solid-phase contact assay that uses a lux-marked nitrosomonas europaea reporter strain to estimate toxicity of bioavailable linear alkylbenzene sulfonate in soil. | information about in situ toxicity of the bioavailable pools of adsorptive soil pollutants is a prerequisite for proper ecological risk assessment in contaminated soils. such toxicity data may be obtained by assays allowing for direct exposure of introduced test microorganisms to the toxicants, as they appear in solid solution equilibria in the natural soil. we describe a novel sensitive solid-phase contact assay for in situ toxicity testing of soil pollutants based on a recombinant bioluminesce ... | 2002 | 12089034 |
| enumerating ammonia-oxidizing bacteria in environmental samples using competitive pcr. | primers targeting part of the ammonia-monooxygenase gene (amoa) have been used to detect and characterize ammonia-oxidizing bacteria (aob) in different environments. in this study, a quantitative polymerase chain reaction (pcr) technique using a competitive template for the amoa primer pair is described and evaluated. the method is based on addition of an internal standard to the pcr, a competitive template, which is amplified together with the template in the environmental sample. by adding dif ... | 2002 | 12133615 |
| exploration of inorganic c and n assimilation by soil microbes with time-of-flight secondary ion mass spectrometry. | stable c and n isotopes have long been used to examine properties of various c and n cycling processes in soils. unfortunately, relatively large sample sizes are needed for accurate gas phase isotope ratio mass spectrometric analysis. this limitation has prevented researchers from addressing c and n cycling issues on microbially meaningful scales. here we explored the use of time-of-flight secondary ion mass spectrometry (tof-sims) to detect 13c and 15n assimilation by individual bacterial cells ... | 2002 | 12147508 |
| use of natural zeolite to enhance nitrification in biofilter. | to enhance nitrification, natural zeolite and activated carbon were tested as a media in a biofilter to treat wastewater containing relatively high concentrations of tkn. using those media, the adsorption isotherms for ammonium ion were compared; the k values for natural zeolite and activated carbon were found to be 0.5117 and 0.0006, respectively. in comparison of the performance of the two media, two identical, lab-scale biofilters were then operated for 4 months. the effect of nh3-n loading r ... | 2002 | 12164639 |
| biodegradation of monohalogenated alkanes by soil nh(3)-oxidizing bacteria. | although cooxidative biodegradation of monohalogenated hydrocarbons has been well studied in the model nh(3)-oxidizing bacterium, nitrosomonas europaea, virtually no information exists about cooxidation of these compounds by native populations of nh(3)-oxidizing bacteria. to address this subject, nitrifying activity was stimulated to 125-400 nmol no(3)(-) produced g(-1) soil h(-1) by first incubating a ca(oh)(2)-amended, silt loam soil (ph 7.0+/-0.2) at field capacity (270 g h(2)o kg(-1) soil) w ... | 2002 | 12172622 |
| oxygen-limited autotrophic nitrification/denitrification by ammonia oxidisers enables upward motion towards more favourable conditions. | the hypothesis is formulated that in case of oxygen limitation in the sediment, nitrifiers switch from nitrification to oxygen-limited autotrophic nitrification-denitrification (oland) in order to survive and maintain activity. during oland, ammonium is oxidised using nitrite as e-acceptor to form dinitrogen gas. as an additional advantage they benefit from the gaseous n(2) formed as a means of transport. in this way, the nitrifiers can move out of the sediment and rise through the water column ... | 2002 | 12172626 |
| in situ characterization of nitrifiers in an activated sludge plant: detection of nitrobacter spp. | the purpose of this work was to investigate microbial ecology of nitrifiers at the genus level in a typical full-scale activated sludge plant. | 2002 | 12174041 |
| identification of active methylotroph populations in an acidic forest soil by stable-isotope probing. | stable-isotope probing (sip) is a culture-independent technique that enables the isolation of dna from micro-organisms that are actively involved in a specific metabolic process. in this study, sip was used to characterize the active methylotroph populations in forest soil (ph 3.5) microcosms that were exposed to (13)ch(3)oh or (13)ch(4). distinct (13)c-labelled dna ((13)c-dna) fractions were resolved from total community dna by cscl density-gradient centrifugation. analysis of 16s rdna sequence ... | 2002 | 12177327 |
| detection of proteobacteria from the rumen by pcr using methanotroph-specific primers. | to detect proteobacteria, including methanotrophs, from the rumen fluid and the bacteria inhabiting the rumen epithelium. | 2002 | 12180951 |
| oxygen-limited nitrogen removal in a lab-scale rotating biological contactor treating an ammonium-rich wastewater. | a lab-scale rotating biological contactor (rbc) was operated with the purpose of oxygen-limited (autotrophic) nitrification-denitrification of an ammonium-rich synthetic wastewater without chemical oxygen demand (cod). based on the field observations that rbcs receiving anaerobic effluents come to anoxic ammonium removal, the rbc was inoculated with methanogenic sludge. some 100 days after the addition of the anaerobic sludge to the reactor as a possible means of a rapid initiation of the nitrog ... | 2002 | 12188571 |
| molecular biology and biochemistry of ammonia oxidation by nitrosomonas europaea. | nitrosomonas europaea uses only nh(3), co(2) and mineral salts for growth and as such it is an obligate chemo-lithoautotroph. the oxidation of nh(3) is a two-step process catalyzed by ammonia monooxygenase (amo) and hydroxylamine oxidoreductase (hao). amo catalyzes the oxidation of nh(3) to nh(2)oh and hao catalyzes the oxidation of nh(2)oh to no(2)(-). amo is a membrane-bound enzyme composed of three subunits. hao is located in the periplasm and is a homotrimer with each subunit containing eigh ... | 2002 | 12209257 |
| production of gaseous nitrogen compounds in a novel process for ammonium removal. | the production of gaseous nitrogen compounds, particularly the greenhouse gas nitrous oxide, was investigated in a novel process for ammonium removal from wastewater. the process is based on the adsorption of ammonium on zeolite followed by bioregeneration. the zeolite serves the dual purpose of an ion exchanger and a physical carrier for nitrifying bacteria which bio-regenerate the ammonium saturated mineral. an analysis of the nitrifying population composition in the reactor fed with simulated ... | 2002 | 12216627 |
| structure and function of nitrifying biofilms as determined by molecular techniques and the use of microelectrodes. | the phylogenetic diversity of a nitrifying bacterial community of two types of nitrifying biofilms, a domestic wastewater biofilm and an autotrophic nitrifying biofilm grown on rotating disk reactors (rdr), was characterized by 16s ribosomal dna (rdna)-cloning analysis. thereafter, successional development of nitrifying the bacterial community within both biofilms was visualized in situ by fluorescent in situ hybridization (fish) wih a set of fluorescently labeled 16s rrna-targeted dna probes. i ... | 2002 | 12216629 |
| molecular analysis of ammonia-oxidizing bacterial populations in aerated-anoxic orbal processes. | aerated-anoxic processes operate under the principle that small additions of oxygen to an anoxic reactor induce simultaneous nitrification and denitrification. in these systems, ammonia oxidation in the anoxic zone can easily account for 30-50% of the total nitrification in the reactor, even though the dissolve oxygen concentration is usually below detection limit. to investigate whether the nitrification efficiency in aerated-anoxic processes was due to the presence of specialized ammonia-oxidi ... | 2002 | 12216636 |
| detection and quantification of expression of amoa by competitive reverse transcription-pcr. | ammonia oxidation by chemolithoautotrophic ammonia-oxidizing bacteria is an important step in the biological nitrogen removal process. the first conversion step, the oxidation of ammonia to hydroxylamine is catalyzed by ammonia monooxygenase (amo). to investigate the activity of ammonia oxidation, mrna (designated as amoa) encoding a subunit of amo was quantified by competitive reverse transcription (rt)-pcr. as a result, it was possible to detect and quantify amoa expression in cultured nitroso ... | 2002 | 12216637 |
| growth at low ammonium concentrations and starvation response as potential factors involved in niche differentiation among ammonia-oxidizing bacteria. | in nature, ammonia-oxidizing bacteria have to compete with heterotrophic bacteria and plants for limiting amounts of ammonium. previous laboratory experiments conducted with nitrosomonas europaea suggested that ammonia-oxidizing bacteria are weak competitors for ammonium. to obtain a better insight into possible methods of niche differentiation among ammonia-oxidizing bacteria, we carried out a growth experiment at low ammonium concentrations with n. europaea and the ammonia oxidizer g5-7, a clo ... | 2002 | 12324316 |
| melissa: a loop of interconnected bioreactors to develop life support in space. | the development of a loop of interconnected continuous bioreactors, aimed to provide life support in space, is reported. the complete loop concept consists of four bioreactors and one higher plant compartment. for its realization the continuous and controlled operation of the bioreactors is characterized, up to the pilot scale level, first for each individual reactor, second for the interconnected reactor operation. the results obtained with the two more advanced bioreactors in the micro ecologi ... | 2002 | 12385718 |
| anaerobic ammonia oxidation in the presence of nitrogen oxides (no(x)) by two different lithotrophs. | the anaerobic ammonia-oxidizing activity of the planctomycete candidatus "brocadia anammoxidans" was not inhibited by no concentrations up to 600 ppm and no2 concentrations up to 100 ppm. b. anammoxidans was able to convert (detoxify) no, which might explain the high no tolerance of this organism. in the presence of no2, the specific ammonia oxidation activity of b. anammoxidans increased, and nitrosomonas-like microorganisms recovered an no2-dependent anaerobic ammonia oxidation activity. addit ... | 2002 | 12406724 |
| effect of soil ammonium concentration on n2o release and on the community structure of ammonia oxidizers and denitrifiers. | the effect of ammonium addition (6.5, 58, and 395 microg of nh4+-n g [dry weight] of soil(-1)) on soil microbial communities was explored. for medium and high ammonium concentrations, increased n2o release rates and a shift toward a higher contribution of nitrification to n2o release occurred after incubation for 5 days at 4 degrees c. communities of ammonia oxidizers were assayed after 4 weeks of incubation by denaturant gradient gel electrophoresis (dgge) of the amoa gene coding for the small ... | 2002 | 12406765 |
| the roles of the three gene copies encoding hydroxylamine oxidoreductase in nitrosomonas europaea. | the nitrifying bacterium nitrosomonas europaea contains three copies of the gene (hao) encoding hydroxylamine oxidoreductase (hao), the second enzyme in the nitrification pathway which oxidizes nh(2)oh to no(2)(-). the nucleotide sequences of the hao genes differ by only one nucleotide. two of the three gene copies have identical promoter sequences, while the third promoter has a different nucleotide sequence. mutant strains with two of the three copies of hao inactivated were created by inserti ... | 2002 | 12420168 |
| cultivation-based and molecular approaches to characterisation of terrestrial and aquatic nitrifiers. | increased awareness of the metabolic diversity within autotrophic nitrifying bacteria has led to a re-evaluation of their role in the cycling of nitrogen in terrestrial and aquatic ecosystems. this has been accompanied by improvements in our ability to characterise natural populations of autotrophic ammonia oxidising bacteria through the application of molecular techniques. molecular approaches indicate considerable diversity within natural populations and the association of different groups of ... | 2002 | 12448715 |
| diversity of nitrifying bacteria in full-scale chloraminated distribution systems. | chloramination for secondary disinfection of drinking water often promotes the growth of nitrifying bacteria in the distribution system due to the ammonia introduced by chloramine formation and decay. this study involved the application of molecular biology techniques to explore the types of ammonia-oxidizing bacteria (aob) and nitrite-oxidizing bacteria (nob) present in several full-scale chloraminated systems. the results of aob community characterization indicated the ubiquitous detection of ... | 2003 | 12465801 |
| quantification of nitrosomonas oligotropha and nitrospira spp. using competitive polymerase chain reaction in bench-scale wastewater treatment reactors operating at different solids retention times. | the effect of solids retention time (srt) on ammonia-and nitrite-oxidizing bacteria was measured by nitrosomonas oligotropha-like ammonia monooxygenase a and nitrospira 16s rdna competitive polymerase chain reaction assays in a complete-mix, bench-scale, activated-sludge system. during steady-state operation, nitrification was complete in the 20- and 10-day srt reactors, nearly complete in the 5-day srt reactor, and incomplete in the 2-day srt reactor (76% ammonia oxidation and 85% nitrite oxida ... | 2002 | 12469950 |
| toxicity assessment of 255 chemicals to pure cultured nitrifying bacteria using biosensor. | the bioassay has been attracting attention as a method of toxicity assessments of micropollutants in the environment. in this study, we report the characteristics (selectivity and sensitivity) of the nitrifying bacteria biosensor for 255 kinds of chemicals as a model of chemical contaminant in the environment and the results of evaluation of mixed samples of several substances. in the nitrifying bacteria respiration inhibition test using the biosensor, 56 chemicals were detected. it was found th ... | 2002 | 12523774 |
| [vfeu water quality control in sts-95 aquatic animal experiment]. | 1999 | 12533005 | |
| real-time pcr quantification of nitrifying bacteria in a municipal wastewater treatment plant. | real-time pcr assays using taqman or molecular beacon probes were developed and optimized for the quantification of total bacteria, the nitrite-oxidizing bacteria nitrospira, and nitrosomonas oligotropha-like ammonia oxidizing bacteria (aob) in mixed liquor suspended solids (mlss) from a municipal wastewater treatment plant (wwtp) using a single-sludge nitrification process. the targets for the real-time pcr assays were the 16s rrna genes (16s rdna) for bacteria and nitrospira spp. and the amoa ... | 2003 | 12564907 |