| anaerobic oxidation of ammonium is a biologically mediated process. | a newly discovered process by which ammonium is converted to dinitrogen gas under anaerobic conditions (the anammox process) has now been examined in detail. in order to confirm the biological nature of this process, anaerobic batch culture experiments were used. all of the ammonium provided in the medium was oxidized within 9 days. in control experiments with autoclaved or raw wastewater, without added sludge or with added sterilized (either autoclaved or gamma irradiated) sludge, no changes in ... | 1995 | 7747947 |
| crystallization and preliminary x-ray analysis of cytochrome c-552 from nitrosomonas europaea. | cytochrome c-552 from nitrosomonas europaea was crystallized by the sandwiched drop, vapor diffusion method, with anmmonium sulfate as the precipitant. the crystals were found to belong to the space group p2(1)2(1)2(1), having unit cell dimensions of a = 106.1 a, b = 126.1 a, and c = 57.7 a. the crystals diffracted x-rays at greater than 3.0 a resolution. | 1994 | 7896754 |
| evolutionary relationships among ammonia- and nitrite-oxidizing bacteria. | comparative 16s rrna sequencing was used to evaluate phylogenetic relationships among selected strains of ammonia- and nitrite-oxidizing bacteria. all characterized strains were shown to be affiliated with the proteobacteria. the study extended recent 16s rrna-based studies of phylogenetic diversity among nitrifiers by the comparison of eight strains of the genus nitrobacter and representatives of the genera nitrospira and nitrospina. the later genera were shown to be affiliated with the delta s ... | 1994 | 7961414 |
| crystallization and preliminary x-ray analysis of cytochrome c-554 from nitrosomonas europaea. | cytochrome c-554 from nitrosomonas europaea was crystallized by the batch method utilizing ammonium sulfate as the precipitant. the crystals belong to the space group, p21, with unit cell dimensions of a = 64.8 a, b = 44.7 a, c = 78.7 a, and beta = 99.0 degrees. the crystals diffracted x-rays beyond 2.5 a resolution. | 1995 | 8586634 |
| a gene encoding a membrane protein exists upstream of the amoa/amob genes in ammonia oxidizing bacteria: a third member of the amo operon? | the gene cluster encoding ammonia monooxygenase (amo) in the chemolithotrophic soil bacterium nitrosospira sp. npav was found to contain a third open reading frame, termed amoc, upstream of the genes amoa and amob that encode the subunits of amo. the amoc gene and its flanking regions were isolated and sequenced from a 4.4 kb ecori fragment that contains one of three copies of the ammonia monooxygenase gene cluster. the presence of this gene upstream of the other two amoa gene copies in nitrosos ... | 1997 | 9163908 |
| the purification of ammonia monooxygenase from paracoccus denitrificans. | the heterotrophic nitrifier paracoccus denitrificans expresses a membrane-associated ammonia monooxygenase. the active enzyme has been solubilized in the detergent dodecyl-beta-d-maltoside and purified by standard chromatographic techniques. this is the first purification of an ammonia monooxygenase. the enzyme consists of two subunits with molecular masses of 38 and 46 kda. the purified enzyme is a quinol oxidase, is inhibited by light and a variety of chelating agents and is activated by cupri ... | 1996 | 8654570 |
| the gene encoding ammonia monooxygenase subunit a exists in three nearly identical copies in nitrosospira sp. npav. | the gene encoding ammonia monooxygenase subunit a (amoa) was found in three copies of the genome of the chemolithotrophic soil bacterium, nitrosospira sp. npav. the open reading frame and flanking regions of the three copies were isolated from digested size fractionated genomic dna using oligodeoxyribonucleotide primers and polymerase chain reaction. the three gene copies of amoa were sequenced and the sequences compared to each other. the open reading frames and the upstream and downstream flan ... | 1996 | 8674986 |
| mutagenesis of hydroxylamine oxidoreductase in nitrosomonas europaea by transformation and recombination. | mutagenesis of nitrosomonas europaea was achieved by electroporation and recombination. to demonstrate this, an aminoglycoside 3'-phosphotransferase (kan) gene was specifically inserted into each of the three gene copies of hao individually. southern hybridizations and pcr analysis showed the incorporation of the kan gene at the chosen genetic loci. the isolation of mutant strains was achieved in 7 to 14 days when the strains were grown on solid medium. the induced mutations were stable even in ... | 1996 | 8682770 |
| comparative analysis of nitrifying bacteria associated with freshwater and marine aquaria. | three nucleic acid probes, two for autotrophic ammonia-oxidizing bacteria of the beta subdivision of the class proteobacteria and one for alpha subdivision nitrite-oxidizing bacteria, were developed and used to study nitrifying bacterial phylotypes associated with various freshwater and seawater aquarium biofilters. nitrosomonas europaea and related species were detected in all nitrifying seawater systems and accounted for as much as 20% of the total eubacterial rrna. in contrast, nitrifying bac ... | 1996 | 8702281 |
| heterologous expression of heterotrophic nitrification genes. | paracoccus denitrificans is a heterotrophic organism capable of oxidizing ammonia to nitrite during growth on an organic carbon and energy source. this pathway, termed heterotrophic nitrification, requires the concerted action of an ammonia monooxygenase (amo) and hydroxylamine oxidase (hao). the genes required for heterotrophic nitrification have been isolated by introducing a pa. denitrificans genomic library into pseudomonas putida and screening for the accumulation of nitrite. in contrast to ... | 1997 | 9421902 |
| crystallization and preliminary crystallographic analysis of cytochrome c553 peroxidase from nitrosomonas europaea. | the di-heme peroxidase (cytochrome c553 peroxidase) from nitrosomonas europaea has been crystallized in a form suitable for high-resolution x-ray structure determination. a complete data set was obtained to 2.5a and the data were indexed in space group p2(1) with a = 88.79 a, b = 55.93 a, c = 144.37 a, beta = 103.87 degrees. the self-rotation function indicates one homodimer per asymmetric unit. | 1996 | 8813001 |
| molecular diversity of soil and marine 16s rrna gene sequences related to beta-subgroup ammonia-oxidizing bacteria. | we have conducted a preliminary phylogenetic survey of ammonia-oxidizing beta-proteobacteria, using 16s rrna gene libraries prepared by selective pcr and dna from acid and neutral soils and polluted and nonpolluted marine sediments. enrichment cultures were established from samples and analyzed by pcr. analysis of 111 partial sequences of c. 300 bases revealed that the environmental sequences formed seven clusters, four of which are novel, within the phylogenetic radiation defined by cultured au ... | 1996 | 8900005 |
| nitrogen removal by tubular gel containing nitrosomonas europaea and paracoccus denitrificans. | a new bioreactor for the removal of nitrogen from wastewater is described which consists of a tubular polymeric gel containing nitrosomonas europaea and paracoccus denitrificans. the outer surface of the tube is in aerobic contact with wastewater containing ammonia, while the inside of the tube is in anaerobic contact with ethanol flowing through the tube. n. europaea oxidizes ammonia to nitrite in the gel, and then p. denitrificans reduces the nitrite to nitrogen gas in the same gel. this conce ... | 1996 | 8900015 |
| optical spectropotentiometric resolution of the hemes of hydroxylamine oxidoreductase. heme quantitation and ph dependence of em. | the hemes of hydroxylamine oxidoreductase (hao) have been analyzed optically by potentiometric titrations using a low volume optically transparent thin layer electrochemical cell. the electrochemical behavior of the hao monomeric unit has been interpreted by modeling the spectroelectrochemical data at several wavelengths to eight one-electron nernst sites: seven c-type hemes and one p460 heme. of the seven c-hemes, six show alpha-bands with absorption maxima at or near 553 nm. one c-heme has an ... | 1993 | 8325842 |
| an electrophoretic study of the thermal- and reductant-dependent aggregation of the 27 kda component of ammonia monooxygenase from nitrosomonas europaea. | standard protocols for sample preparation for sodium dodecyl sulfate-polyacrylamide gel electrophoresis (sds-page) typically involve the combined use of heat and a reductant to fully disrupt protein-protein interactions and allow for constant ratios of sds-binding to individual polypeptides. however, 14c-labeled forms of the membrane-bound, active-site-containing 27 kda polypeptide of ammonia monooxygenase from nitrosomonas europaea undergo an aggregation reaction when cells or membranes are hea ... | 1993 | 8375353 |
| evidence for an iron center in the ammonia monooxygenase from nitrosomonas europaea. | binding of the ligand, nitric oxide, in the presence of reductant was used to identify a ferrous s = 3/2 signal, characteristic of a ferrous nitrosyl complex, and a g= 2.03 copper or iron signal in membranes of the ammonia-oxidizing bacterium, nitrosomonas europaea. the same ferrous s = 3/2 signal is thought to be a component of the membrane-associated methane monooxygenase (pmmo) of methylococcus capsulatus bath, since it is seen in the membrane fraction of cells expressing pmmo and in the puri ... | 1996 | 8941709 |
| structure and function of a nitrifying biofilm as determined by in situ hybridization and the use of microelectrodes. | microprofiles of o2 and no3- were measured in nitrifying biofilms from the trickling filter of an aquaculture water recirculation system. by use of a newly developed biosensor for no3-, it was possible to avoid conventional interference from other ions. nitrification was restricted to a narrow zone of 50 microns on the very top of the film. in the same biofilms, the vertical distributions of members of the lithoautotrophic ammonia-oxidizing genus nitrosomonas and of the nitrite-oxidizing genus n ... | 1996 | 8953735 |
| hydroxylamine oxidoreductase from nitrosomonas europaea is a multimer of an octa-heme subunit. | a fully active form of hydroxylamine oxidoreductase from nitrosomonas has been purified with high recovery and shown by reverse-phase high performance liquid chromatography and n-terminal analysis to contain only a 63-kda subunit and to lack the 11-kda protein previously thought to be a second subunit. based on the previously published values of molecular weight in solution, hydroxylamine oxidoreductase probably has an alpha 2 or alpha 3 oligomeric structure. the enzyme was digested separately w ... | 1993 | 8325841 |
| linkage of genes encoding enolase (eno) and ctp synthase (pyrg) in the beta-subdivision proteobacterium nitrosomonas europaea. | the gene encoding enolase (eno) from the ammonia oxidising bacterium nitrosomonas europaea has been cloned and sequenced. the deduced amino acid sequence for enolase from n. europaea was 65% identical (76% similar) to its bacillus subtilis orthologue. an incomplete open reading frame located 432 bp 5' of eno was identified as pyrg, which encodes ctp synthase. these two genes are therefore organised in n. europaea, a beta-subdivision proteobacterium, in the same way as in the gamma-subdivision pr ... | 1998 | 9711852 |
| metal selectivity of in situ microcolonies in biofilms of the elbe river. | the ultrastructure of natural complex biofilm communities of the elbe river grown in situ on microscopic glass coverslips was studied by using transmission electron microscopy and energy-dispersive x-ray (edx) analysis. characteristic microcolonies which measured between 3.3 and 9.3 microm in diameter were frequently observed. they had an outer envelope and harbored 6 to 30 cells. the cells formed short rods measuring 1.09 +/- 0.28 microm (n = 10) in length and 0.55 + 0.07 microm (n = 21) in wid ... | 1997 | 8981977 |
| physiological and molecular biological characterization of ammonia oxidation of the heterotrophic nitrifier pseudomonas putida. | the heterotrophic nitrifier pseudomonas putida aerobically oxidized ammonia to hydroxylamine, nitrite, and nitrate. product formation was accompanied by a small but significant release of no, whereas n2o evolution could not be detected under the assay conditions employed. the isolate reduced nitrate to nitrite and partially further to no under anaerobic conditions. aerobically grown cells utilized gamma-aminobutyrate as a carbon source and as a n-source by ammonification. the physiological exper ... | 1998 | 9732537 |
| anaerobic ammonia oxidation with nitrogen dioxide by nitrosomonas eutropha | nitrosomonas eutropha, an obligately lithoautotrophic bacterium, was able to nitrify and denitrify simultaneously under anoxic conditions when gaseous nitrogen dioxide (no2) was supplemented to the atmosphere. in the presence of gaseous no2, ammonia was oxidized, nitrite and nitric oxide (no) were formed, and hydroxylamine occurred as an intermediate. between 40 and 60% of the produced nitrite was denitrified to dinitrogen (n2). nitrous oxide (n2o) was shown to be an intermediate of denitrificat ... | 1997 | 9042749 |
| the use of a hollow fiber membrane module in sample conditioning prior to electrophoresis. | a new method to continuously change the buffer conditions in samples prior to electrophoresis by counter-current dialysis has been developed using a hollow fiber membrane module (variperm m, bitop, witten). it is demonstrated that the collected fractions of a column eluate after hydrophobic interaction chromatography cannot be analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (sds-page) due to the high content of ammonium sulfate. in contrast, when the hollow fiber membrane m ... | 1994 | 7859717 |
| the remarkable complexity of hydroxylamine oxidoreductase. | | 1997 | 9095186 |
| the 2.8 a structure of hydroxylamine oxidoreductase from a nitrifying chemoautotrophic bacterium, nitrosomonas europaea. | the 2.8 a crystal structure of hydroxylamine oxidoreductase of a nitrifying chemoautotrophic bacterium, nitrosomonas europaea, is described. twenty-four haems lie in the centre bottom of the trimeric molecule, localized in four clusters within each monomer. the haem clusters within the trimer are aligned to form a ring that has inlet and outlet sites. the inlet is occupied by a novel haem, p460, and there are two possible outlet sites per monomer formed by paired haems lying within a cavity or c ... | 1997 | 9095195 |
| a bioluminescence assay using nitrosomonas europaea for rapid and sensitive detection of nitrification inhibitors. | an expression vector for the luxab genes, derived from vibrio harveyi, was introduced into nitrosomonas europaea. although the recombinant strain produced bioluminescence due to the expression of the luxab genes under normal growing conditions, the intensity of the light emission decreased immediately, in a time-and dose-dependent manner, with the addition of ammonia monooxygenase inhibitors, such as allylthiourea, phenol, and nitrapyrin. when whole cells were challenged with several nitrificati ... | 1998 | 9758781 |
| the biochemical characterization of a novel non-haem-iron hydroxylamine oxidase from paracoccus denitrificans gb17. | the characterization of the hydroxylamine oxidase from the heterotrophic nitrifier paracoccus denitrificans gb17 indicates the enzyme to be entirely distinct from the hydroxylamine oxidase from the autotrophic nitrifier nitrosomonas europaea. hydroxylamine oxidase from p. denitrificans contains three to five non-haem, non-iron-sulphur iron atoms as prosthetic groups, predominantly co-ordinated by carboxylate ligands. the interaction of the enzyme with the electron-accepting proteins cytochrome c ... | 1996 | 8920986 |
| loss of ammonia monooxygenase activity in nitrosomonas europaea upon exposure to nitrite | nitrosomonas europaea, an obligate ammonia-oxidizing bacterium, lost an increasing amount of ammonia oxidation activity upon exposure to increasing concentrations of nitrite, the primary product of ammonia-oxidizing metabolism. the loss of activity was specific to the ammonia monooxygenase (amo) enzyme, as confirmed by a decreased rate of nh4+-dependent o2 consumption, some loss of active amo molecules observed by polypeptide labeling with 14c2h2, the protection of activity by substrates of amo, ... | 1998 | 9758853 |
| consideration of a phlorin structure for haem p-460 of hydroxylamine oxidoreductase and its implications regarding reaction mechanism. | | 1998 | 9765884 |
| transcription of the amoc, amoa and amob genes in nitrosomonas europaea and nitrosospira sp. npav. | nitrifying bacteria such as nitrosomonas europaea and nitrosospira sp. npav use ammonia monooxygenase (amo) for oxidation of their primary growth substrate, ammonia. two polypeptides of amo are coded for by contiguous genes, amoa and amob, which are preceded by a third gene, amoc. the amocab clusters are present in multiple copies in nitrifying bacteria of the beta subdivision. these bacteria also have one amoc copy that is not adjacent to a copy of amoab. the seven known amoc genes in different ... | 1998 | 9785456 |
| in vitro activation of ammonia monooxygenase from nitrosomonas europaea by copper. | the effect of copper on the in vivo and in vitro activity of ammonia monooxygenase (amo) from the nitrifying bacterium nitrosomonas europaea was investigated. the addition of cucl2 to cell extracts resulted in 5- to 15-fold stimulation of ammonia-dependent o2 consumption, ammonia-dependent nitrite production, and hydrazine-dependent ethane oxidation. amo activity was further stimulated in vitro by the presence of stabilizing agents, including serum albumins, spermine, or mgcl2. in contrast, the ... | 1993 | 8458839 |
| sequence of the gene coding for ammonia monooxygenase in nitrosomonas europaea. | nitrosomonas europaea, a chemolithotrophic bacterium, was found to contain two copies of the gene coding for the presumed active site polypeptide of ammonia monooxygenase, the 32-kda acetylene-binding polypeptide. one copy of this gene was cloned, and its complete nucleotide sequence is presented. immediately downstream of this gene, in the same operon, is the gene for a 40-kda polypeptide that copurifies with the ammonia monooxygenase acetylene-binding polypeptide. the sequence of the first 692 ... | 1993 | 8468301 |
| assessment of changes in microbial community structure during operation of an ammonia biofilter with molecular tools. | biofiltration has been used for two decades to remove odors and various volatile organic and inorganic compounds in contaminated off-gas streams. although biofiltration is widely practiced, there have been few studies of the bacteria responsible for the removal of air contaminants in biofilters. in this study, molecular techniques were used to identify bacteria in a laboratory-scale ammonia biofilter. both 16s rrna and ammonia monooxygenase (amoa) genes were used to characterize the heterotrophi ... | 1998 | 9835577 |
| cytochrome p460 genes from the methanotroph methylococcus capsulatus bath. | p460 cytochromes catalyze the oxidation of hydroxylamine to nitrite. they have been isolated from the ammonia-oxidizing bacterium nitrosomonas europaea (r. h. erickson and a. b. hooper, biochim. biophys. acta 275:231-244, 1972) and the methane-oxidizing bacterium methylococcus capsulatus bath (j. a. zahn et al., j. bacteriol. 176:5879-5887, 1994). a degenerate oligonucleotide probe was synthesized based on the n-terminal amino acid sequence of cytochrome p460 and used to identify a dna fragment ... | 1998 | 9851984 |
| isolation and characterization of a functional promoter from nitrosomonas europaea. | a functional promoter from the obligate autotrophic ammonia oxidizing bacterium nitrosomonas europaea was identified by expression in escherichia coli, using a promoterless reporter gene. transcription initiation site of this promoter was determined by primer extension analysis. the sequences at -35 and -10 have low similarity to the -10/-35 consensus sequence of known prokaryotic promoters. | 1996 | 8935651 |
| analysis of ammonia-oxidizing bacteria of the beta subdivision of the class proteobacteria in coastal sand dunes by denaturing gradient gel electrophoresis and sequencing of pcr-amplified 16s ribosomal dna fragments. | denaturing gradient gel electrophoresis (dgge) is a powerful and convenient tool for analyzing the sequence diversity of complex natural microbial populations. dgge was evaluated for the identification of ammonia oxidizers of the beta subdivision of the proteobacteria based on the mobility of pcr-amplified 16s rdna fragments and for the analysis of mixtures of pcr products from this group generated by selective pcr of dna extracted from coastal sand dunes. degenerate pcr primers, cto189f-gc and ... | 1997 | 9097446 |
| cell density-regulated recovery of starved biofilm populations of ammonia-oxidizing bacteria. | the speed of recovery of cell suspensions and biofilm populations of the ammonia oxidizer nitrosomonas europaea, following starvation was determined. stationary-phase cells, washed and resuspended in ammoniumfree inorganic medium, were starved for periods of up to 42 days, after which the medium was supplemented with ammonium and subsequent growth was monitored by measuring nitrite concentration changes. cultures exhibited a lag phase prior to exponential nitrite production, which increased from ... | 1997 | 9172348 |
| effect of ammonia starvation on hydroxylamine oxidoreductase activity of nitrosomonas europaea. | a technique for detection of the activity of hydroxylamine oxidoreductase (hao) involving denaturing sds-polyacrylamide gels was developed. the activity of hao of nitrosomonas europaea was assayed using this technique, which revealed a single active band of 140 kda. the hao activity of other ammonia-oxidizers was also resistant to sds, the molecular weights being identical to that of n. europaea. n. europaea cells starved of ammonia for up to 72 h retained a considerable amount of hao, as detect ... | 1997 | 9192739 |
| evidence for a crosslink between c-heme and a lysine residue in cytochrome p460 of nitrosomonas europaea. | cytochrome p460 and hydroxylamine oxidoreductase (hao) of nitrosomonas europaea catalyze the oxidation of hydroxylamine. cytochrome p460 contains an unidentified heme-like chromophore whose distinctive spectroscopic properties are similar to those for the p460 heme found in hao. the heme p460 of hao has previously been shown by protein chemistry and nmr structural analysis to be a c-heme with an additional covalent crosslink between the c2 ring carbon of a tyrosine residue of the polypeptide cha ... | 1997 | 9237682 |
| phylogenetic differences between particle-associated and planktonic ammonia-oxidizing bacteria of the beta subdivision of the class proteobacteria in the northwestern mediterranean sea. | the aim of this study was to determine if there were differences between the types of ammonia-oxidizing bacteria of the beta subdivision of the class proteobacteria associated with particulate material and planktonic samples obtained from the northwestern mediterranean sea. a nested pcr procedure performed with ammonia oxidizer-selective primers was used to amplify 16s rrna genes from extracted dna. the results of partial and full-length sequence analyses of 16s rrna genes suggested that differe ... | 1999 | 9925616 |
| the ammonia monooxygenase structural gene amoa as a functional marker: molecular fine-scale analysis of natural ammonia-oxidizing populations. | the naturally occurring genetic heterogeneity of autotrophic ammonia-oxidizing populations belonging to the beta subclass of the proteobacteria was studied by using a newly developed pcr-based assay targeting a partial stretch of the gene which encodes the active-site polypeptide of ammonia monooxygenase (amoa). the pcr yielded a specific 491-bp fragment with all of the nitrifiers tested, but not with the homologous stretch of the particulate methane monooxygenase, a key enzyme of methane-oxidiz ... | 1997 | 9406389 |
| correlation of optical and epr signals with the p460 heme of hydroxylamine oxidoreductase from nitrosomonas europaea. | hydroxylamine oxidoreductase (hao) of nitrosomonas europaea catalyzes the four-electron oxidation of nh2oh to no2-. each subunit of the trimeric enzyme contains seven c-hemes and one heme p460. in previous work [hendrich, m. p., et al. (1994) j. am. chem. soc. 116, 11961-11968], an integer-spin epr signal at g = 7.7 was discovered from the active site of the resting enzyme. this new signal was assigned to an exchange-coupled cluster containing ferric heme p460 and a ferric c-heme. an electrochem ... | 1998 | 9425072 |
| dna-probing for genes coding for denitrification, n2-fixation and nitrification in bacteria isolated from different soils. | bacteria isolated from different layers of four soils of the cologne area were analyzed for denitrifying, nitrifying and n2-fixing isolates by colony hybridization using gene probes. in the soils tested, the percentage of denitrifying bacteria among the total population isolated was 3-8% (in one case exceptionally 15%) and thus small. denitrifying bacteria were particularly enriched in the upper layer (depth approximately 5 cm) and were present only in low amounts at 25 cm depth in two gleysol s ... | 1998 | 9528124 |
| maintenance energy demand and starvation recovery dynamics of nitrosomonas europaea and nitrobacter winogradskyi cultivated in a retentostat with complete biomass retention. | nitrosomonas europaea and nitrobacter winogradskyi (strain "engel") were grown in ammonia-limited and nitrite-limited conditions, respectively, in a retentostat with complete biomass retention at 25 degrees c and ph 8. fitting the retentostat biomass and oxygen consumption data of n. europaea and n. winogradskyi to the linear equation for substrate utilization resulted in up to eight-times-lower maintenance requirements compared to the maintenance energy demand (m) calculated from chemostat expe ... | 1999 | 10347029 |
| enzymology of the oxidation of ammonia to nitrite by bacteria. | the enzymes which catalyze the oxidation of ammonia to nitrite by autotrophic bacteria are reviewed. a comparison is made with enzymes which catalyze the same reactions in methylotrophs and organotrophic heterotrophic bacteria. | 1997 | 9049018 |
| isolation and characterization of two cryptic plasmids in the ammonia-oxidizing bacterium nitrosomonas sp. strain eni-11. | two plasmids were discovered in the ammonia-oxidizing bacterium nitrosomonas sp. strain eni-11, which was isolated from activated sludge. the plasmids, designated pays and payl, were relatively small, being approximately 1.9 kb long. they were cryptic plasmids, having no detectable plasmid-linked antibiotic resistance or heavy metal resistance markers. the complete nucleotide sequences of pays and payl were determined, and their physical maps were constructed. there existed two major open readin ... | 1999 | 10348848 |
| mutagenesis and expression of amo, which codes for ammonia monooxygenase in nitrosomonas europaea. | nitrosomonas europaea has two copies of the operon encoding ammonia monooxygenase (amo). the nucleotide sequences of the two copies of amoa were obtained, and they were found to differ by one nucleotide. to determine if both copies of amoa were functional, insertional mutagenesis was performed to inactivate either copy of amoa alone. a dna cassette containing the lacz and kan genes inserted into amoa was constructed. mutagenesis was done by using transformation and homologous recombination to mo ... | 1998 | 9642187 |
| molecular analysis of bacterial communities in a three-compartment granular activated sludge system indicates community-level control by incompatible nitrification processes. | bacterial community structure and the predominant nitrifying activities and populations in each compartment of a three-compartment activated sludge system were determined. each compartment was originally inoculated with the same activated sludge community entrapped in polyethylene glycol gel granules, and ammonium nitrogen was supplied to the system in an inorganic salts solution at a rate of 5.0 g of n liter of granular activated sludge-1 day-1. after 150 days of operation, the system was found ... | 1998 | 9647825 |
| analysis of beta-subgroup proteobacterial ammonia oxidizer populations in soil by denaturing gradient gel electrophoresis analysis and hierarchical phylogenetic probing | a combination of denaturing gradient gel electrophoresis (dgge) and oligonucleotide probing was used to investigate the influence of soil ph on the compositions of natural populations of autotrophic beta-subgroup proteobacterial ammonia oxidizers. pcr primers specific to this group were used to amplify 16s ribosomal dna (rdna) from soils maintained for 36 years at a range of ph values, and pcr products were analyzed by dgge. genus- and cluster-specific probes were designed to bind to sequences w ... | 1998 | 9687457 |
| combined molecular and conventional analyses of nitrifying bacterium diversity in activated sludge: nitrosococcus mobilis and nitrospira-like bacteria as dominant populations. | the ammonia-oxidizing and nitrite-oxidizing bacterial populations occurring in the nitrifying activated sludge of an industrial wastewater treatment plant receiving sewage with high ammonia concentrations were studied by use of a polyphasic approach. in situ hybridization with a set of hierarchical 16s rrna-targeted probes for ammonia-oxidizing bacteria revealed the dominance of nitrosococcus mobilis-like bacteria. the phylogenetic affiliation suggested by fluorescent in situ hybridization (fish ... | 1998 | 9687471 |
| amplification of 16s ribosomal rna genes of autotrophic ammonia-oxidizing bacteria demonstrates the ubiquity of nitrosospiras in the environment. | oligonucleotide sequences selected from the 16s rrna genes of various species of ammonia-oxidizing bacteria were evaluated as specific pcr amplification primers and probes. the specificities of primer pairs for eubacterial, nitrosospira and nitrosomonas rrna genes were established with sequence databases, and the primer pairs were used to amplify dna from laboratory cultures and environmental samples. eubacterial rrna genes amplified from samples of soil and activated sludge hybridized with an o ... | 1995 | 8535507 |
| phylogenetic differentiation of two closely related nitrosomonas spp. that inhabit different sediment environments in an oligotrophic freshwater lake. | the population of ammonia-oxidizing bacteria in a temperate oligotrophic freshwater lake was analyzed by recovering 16s ribosomal dna (rdna) from lakewater and sediment samples taken throughout a seasonal cycle. nitrosospira and nitrosomonas 16s rrna genes were amplified in a nested pcr, and the identity of the products was confirmed by oligonucleotide hybridization. nitrosospira dna was readily identified in all samples, and nitrosomonad dna of the nitrosomonas europaea-nitrosomonas eutropha li ... | 1999 | 10543796 |
| identification and activities in situ of nitrosospira and nitrospira spp. as dominant populations in a nitrifying fluidized bed reactor. | bacterial aggregates from a chemolithoautotrophic, nitrifying fluidized bed reactor were investigated with microsensors and rrna-based molecular techniques. the microprofiles of o2, nh4+, no2-, and no3- demonstrated the occurrence of complete nitrification in the outer 125 microgram of the aggregates. the ammonia oxidizers were identified as members of the nitrosospira group by fluorescence in situ hybridization (fish). no ammonia- or nitrite-oxidizing bacteria of the genus nitrosomonas or nitro ... | 1998 | 9726900 |
| high rate of aerobic nitrification and denitrification by nitrosomonas eutropha grown in a fermentor with complete biomass retention in the presence of gaseous no2 or no. | a pure culture of the obligately lithoautotrophic ammonia-oxidizer nitrosomonas eutropha was grown in a laboratory-scale bioreactor with complete biomass retention. the air supply was supplemented with nitrogen dioxide (no2; 25 or 50 ppm) or nitric oxide (no; 25 or 50 ppm). compared to cultures grown without these nitrogenous oxides, the addition of no2 or no to the culture resulted in a significant increase of the nitrification rate, specific activity of ammonia oxidation, growth rate, and maxi ... | 1998 | 9531628 |
| physical map location of the multicopy genes coding for ammonia monooxygenase and hydroxylamine oxidoreductase in the ammonia-oxidizing bacterium nitrosomonas sp. strain eni-11. | pulsed-field gel electrophoresis of pmei digests of the nitrosomonas sp. strain eni-11 chromosome produced four bands ranging from 1,200 to 480 kb in size. southern hybridizations suggested that a 487-kb pmei fragment contained two copies of the amocab genes, coding for ammonia monooxygenase (designated amocab(1) and amocab(2)), and three copies of the hao gene, coding for hydroxylamine oxidoreductase (hao(1), hao(2), and hao(3)). in this dna fragment, amocab(1) and amocab(2) were about 390 kb a ... | 2000 | 10633121 |
| simultaneous nitrification and denitrification using immobilized microorganisms. | nitrogen removal from wastewaters is a multiple step process in which nitrification is often a problem due to the slow growth rates of the nitrifying bacteria. by immobilization of these bacteria, nitrification can be efficiently accomplished in compact reactors. in this paper, the possibilities of integrated nitrification and denitrification within a single reactor system are evaluated. two main systems are studied: a) nitrosamines europaea and pseudomonas denitrificans co-immobilized in a a ge ... | 1993 | 8399972 |
| distribution of nitrosomonas europaea and paracoccus denitrificans immobilized in tubular polymeric gel for nitrogen removal. | to improve the cooperative removal of nitrogen by nitrosomonas europaea and paracoccus denitrificans, we controlled their distribution in a tubular gel. when ethanol was supplied inside the tubular gel as an electron donor, their distributions overlapped in the external region of the gel. by changing the electron donor from ethanol to gaseous hydrogen, the distribution of p. denitrificans shifted to the inside of the tube and was separated from that of n. europaea. the separation resulted in an ... | 2000 | 10653756 |
| primary sequence and solution conformation of ferrocytochrome c-552 from nitrosomonas europaea. | cytochrome c-552 from nitrosomonas europaea is a 9.1-kda monoheme protein that is a member of the bacterial cytochrome c-551 family. the gene encoding for c-552 has been cloned and sequenced and the primary sequence of the product deduced. proton resonance assignments were made for all main-chain and most side-chain protons in the diamagnetic, reduced form by two-dimensional nmr techniques. distance constraints (1056) were determined from nuclear overhauser enhancements, and torsion angle constr ... | 1998 | 9746537 |
| effect of long-term ammonia starvation on the oxidation of ammonia and hydroxylamine by nitrosomonas europaea. | axenic cultures of the ammonia-oxidizing bacterium nitrosomonas europaea were starved of ammonia (energy source) for up to 342 d. during this time the bacteria retained the ability to respond instantly to ammonia (1 mm) or hydroxylamine (0.1 mm) amendment by oxidizing it to nitrite without initial protein synthesis. in vivo, the ability to oxidize amended ammonia stayed almost constant during the starvation period, but a drop in the hydroxylamine oxidation rate (to 33%) was observed after 4 wk o ... | 1998 | 9756628 |
| molecular analysis of ammonia-oxidising bacteria in soil of successional grasslands of the drentsche a (the netherlands). | changes in the community structure of chemolitho-autotrophic ammonia-oxidising bacteria of the beta-subgroup proteobacteria were monitored during nutrient-impoverishment management of slightly acidic, peaty grassland soils, which decreased in ph with succession. specific pcr, cloning and sequence analysis, denaturing gradient gel electrophoresis (dgge) and probe hybridisation were used to analyse rdna sequences directly recovered from successional soils. four previously characterised ammonia oxi ... | 2000 | 10719201 |
| analysis of ammonia-oxidizing bacteria populations in acid forest soil during conditions of moisture limitation. | ammonia-oxidizer numbers decreased under conditions of moisture limitation in litter, fermentation and humus layers of forest soil in the field, but the extent of regrowth after rehydration varied between layers. nitrosospira 16s rrna genes were amplified from all layers, regardless of moisture content or soil ph which varied between 4.1 and 5.2. nitrosomonas spp. were detected less often, but appeared to exhibit more rapid recovery than the nitrosospira spp. when drought conditions were relieve ... | 2000 | 10728553 |
| detection of groel in activated sludge: a model for detection of system stress. | groel is a ubiquitous constitutively synthesized protein that is also stress inducible. activated sludge, which is a standard biological process used in wastewater treatment systems, is made up of a diverse microbial consortium. the synthesis of groel in activated sludge was significantly induced after heat (42 degrees c) shock. the increased level of groel expression was shown to be due to de novo protein synthesis. we have demonstrated a method which shows that stress proteins can be detected ... | 2000 | 10728556 |
| effects of ph and oxygen and ammonium concentrations on the community structure of nitrifying bacteria from wastewater | shifts in nitrifying community structure and function in response to different ammonium concentrations (50, 500, 1,000, and 3,000 mg of n liter-1), ph values (ph 6.0, 7.0, and 8.2), and oxygen concentrations (1, 7, and 21%) were studied in experimental reactors inoculated with nitrifying bacteria from a wastewater treatment plant. the abilities of the communities selected for these conditions to regain their original structures after conditions were returned to the original conditions were also ... | 1998 | 9758771 |
| application of molecular biological techniques to a seasonal study of ammonia oxidation in a eutrophic freshwater lake | the autotrophic ammonia-oxidizing bacteria in a eutrophic freshwater lake were studied over a 12-month period. numbers of ammonia oxidisers in the lakewater were small throughout the year, and tangential-flow concentration was required to obtain meaningful estimates of most probable numbers. sediments from littoral and profundal sites supported comparatively large populations of these bacteria, and the nitrification potential was high, particularly in summer samples from the littoral sediment su ... | 1998 | 9758784 |
| anaerobic ammonia oxidation by cell-free extracts of nitrosomonas eutropha. | cell-free extracts of nitrosomonas eutropha oxidized ammonia to nitrite with no2 (n2o4) as electron acceptor. the ammonia oxidation activity was shown to be sensitive against oxygen. in the absence of oxygen ammonia and no2 were consumed in a ratio of approximately 1:2 and hydroxylamine occurred as an intermediate. no was released in amounts equimolar to the consumption of no2. after passing the cell suspension through a french pressure cell and fractionating it by density gradient centrifugatio ... | 1998 | 9801772 |
| effects of soil and water content on methyl bromide oxidation by the ammonia-oxidizing bacterium nitrosomonas europaea. | little information exists on the potential of nh(3)-oxidizing bacteria to cooxidize halogenated hydrocarbons in soil. a study was conducted to examine the cooxidation of methyl bromide (mebr) by an nh(3)-oxidizing bacterium, nitrosomonas europaea, under soil conditions. soil and its water content modified the availability of nh(4)(+) and mebr and influenced the relative rates of substrate (nh(3)) and cosubstrate (mebr) oxidations. these observations highlight the complexity associated with chara ... | 2000 | 10831449 |
| a qualitative evaluation of the published oligonucleotides specific for the 16s rrna gene sequences of the ammonia-oxidizing bacteria. | over the past few years, there has been an increasing interest in making oligonucleotides specific for ammonia-oxidizing bacteria (aob), in order to detect and monitor these slow growing bacteria in environmental samples, in enrichment cultures and in wastewater treatment plants. based on 16s rdna sequences, a broad selection of oligonucleotides have been designed, either encompassing all known aob in the beta-subgroup of the proteobacteria (beta aob), or subclasses within beta aob. thirty diffe ... | 1998 | 9741112 |
| analysis of ammonia-oxidizing bacteria from hypersaline mono lake, california, on the basis of 16s rrna sequences. | ammonia-oxidizing bacteria were detected by pcr amplification of dna extracted from filtered water samples throughout the water column of mono lake, california. ammonia-oxidizing members of the beta subdivision of the division proteobacteria (beta-subdivision proteobacteria) were detected using previously characterized pcr primers; target sequences were detected by direct amplification in both surface water and below the chemocline. denaturing gradient gel electrophoresis analysis indicated the ... | 2000 | 10877781 |
| functional gene hybridization patterns of terrestrial ammonia-oxidizing bacteria. | abstract the biochemical pathway and genetics of autotrophic ammonia oxidation have been studied almost exclusively in nitrosomonas europaea. terrestrial autotrophic ammonia-oxidizing bacteria (aaos), however, comprise two distinct phylogenetic groups in the beta-proteobacteria, the nitrosomonas and nitrosospira groups. hybridization patterns were used to assess the potential of functional probes in non-pcr-based molecular analysis of natural aao populations and their activity. the objective of ... | 1998 | 9852509 |
| primary structure of cytochrome c' of methylococcus capsulatus bath: evidence of a phylogenetic link between p460 and c'-type cytochromes. | cytochrome c' of methylococcus capsulatus bath is involved in electron flow from the enzyme responsible for hydroxylamine oxidation, cytochrome p460, to cytochrome c555. this cytochrome is spectrally similar to other cytochromes c' but is larger (16,000 da) and has a lower midpoint potential (-205 mv). by a combination of edman degradation, mass spectroscopy, and gene sequencing, we have obtained the primary structure of cytochrome c' from m. capsulatus bath. the cytochrome shows low sequence si ... | 2000 | 10648101 |
| cloning, nucleotide sequence, and regulatory analysis of the nitrosomonas europaea dnak gene. | the dnak gene of an ammonia-oxidizing bacterium, nitrosomonas europaea, was cloned and sequenced. it was found that the dnak gene product was highly homologous to previously analyzed dnak gene products from other organisms at the amino acid level. two partial open reading frames located upstream and downstream of the dnak gene were also found and identified as grpe and dnaj genes, respectively, by the predicted amino acid homology of their gene products to other bacterial grpe and dnaj proteins. ... | 1997 | 9143112 |
| nitrogen cycling and community structure of proteobacterial beta-subgroup ammonia-oxidizing bacteria within polluted marine fish farm sediments. | a multidisciplinary approach was used to study the effects of pollution from a marine fish farm on nitrification rates and on the community structure of ammonia-oxidizing bacteria in the underlying sediment. organic content, ammonium concentrations, nitrification rates, and ammonia oxidizer most-probable-number counts were determined in samples of sediment collected from beneath a fish cage and on a transect at 20 and 40 m from the cage. the data suggest that nitrogen cycling was significantly d ... | 1999 | 9872782 |
| molecular analysis of ammonia-oxidizing bacteria of the beta subdivision of the class proteobacteria in compost and composted materials. | although the practice of composting animal wastes for use as biofertilizers has increased in recent years, little is known about the microorganisms responsible for the nitrogen transformations which occur in compost and during the composting process. ammonia is the principle available nitrogenous compound in composting material, and the conversion of this compound to nitrite in the environment by chemolithotrophic ammonia-oxidizing bacteria is an essential step in nitrogen cycling. therefore, th ... | 1999 | 9925559 |
| the anaerobic oxidation of ammonium. | from recent research it has become clear that at least two different possibilities for anaerobic ammonium oxidation exist in nature. 'aerobic' ammonium oxidizers like nitrosomonas eutropha were observed to reduce nitrite or nitrogen dioxide with hydroxylamine or ammonium as electron donor under anoxic conditions. the maximum rate for anaerobic ammonium oxidation was about 2 nmol nh4+ min-1 (mg protein)-1 using nitrogen dioxide as electron acceptor. this reaction, which may involve no as an inter ... | 1998 | 9990725 |
| recovery of a nitrosomonas-like 16s rdna sequence group from freshwater habitats. | in order to study the diversity of ammonia-oxidising bacteria in freshwater habitats, including sediments, a molecular approach focused on the sequencing of 16s rdna was adopted. 16s rdna sequences showing affinity with the beta-subgroup of ammonia-oxidising bacteria were recovered by specific pcr of directly isolated dna from freshwater samples, and samples from brackish water and glyceria maxima rhizosphere were included in the analysis for comparison. the ammonia oxidiser-like sequences recov ... | 1998 | 9704117 |
| anaerobic ammonia oxidation with nitrogen dioxide by nitrosomonas eutropha. | nitrosomonas eutropha, an obligately lithoautotrophic bacterium, was able to nitrify and denitrify simultaneously under anoxic conditions when gaseous nitrogen dioxide (no2) was supplemented to the atmosphere. in the presence of gaseous no2, ammonia was oxidized, nitrite and nitric oxide (no) were formed, and hydroxylamine occurred as an intermediate. between 40 and 60% of the produced nitrite was denitrified to dinitrogen (n2). nitrous oxide (n2o) was shown to be an intermediate of denitrificat ... | 1997 | 9133316 |
| nitrous oxide production and methane oxidation by different ammonia-oxidizing bacteria. | ammonia-oxidizing bacteria (aob) are thought to contribute significantly to n2o production and methane oxidation in soils. most of our knowledge derives from experiments with nitrosomonas europaea, which appears to be of minor importance in most soils compared to nitrosospira spp. we have conducted a comparative study of levels of aerobic n2o production in six phylogenetically different nitrosospira strains newly isolated from soils and in two n. europaea and nitrosospira multiformis type strain ... | 1999 | 10347060 |
| comparative diversity of ammonia oxidizer 16s rrna gene sequences in native, tilled, and successional soils. | autotrophic ammonia oxidizer (aao) populations in soils from native, tilled, and successional treatments at the kellogg biological station long-term ecological research site in southwestern michigan were compared to assess effects of disturbance on these bacteria. n fertilization effects on aao populations were also evaluated with soils from fertilized microplots within the successional treatments. population structures were characterized by pcr amplification of microbial community dna with grou ... | 1999 | 10388694 |
| in situ analysis of nitrifying biofilms as determined by in situ hybridization and the use of microelectrodes. | we investigated the in situ spatial organization of ammonia-oxidizing and nitrite-oxidizing bacteria in domestic wastewater biofilms and autotrophic nitrifying biofilms by using microsensors and fluorescent in situ hybridization (fish) performed with 16s rrna-targeted oligonucleotide probes. the combination of these techniques made it possible to relate in situ microbial activity directly to the occurrence of nitrifying bacterial populations. in situ hybridization revealed that bacteria belongin ... | 1999 | 10388720 |
| 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 |
| construction of a highly bioluminescent nitrosomonas as a probe for nitrification conditions. | cloned luciferase-encoding operons were transferred by conjugation to a natural isolate of the ammonia-oxidizing bacterial strain nitrosomonas sp. rst41-3, thereby establishing conjugation as a tool for gene transfer into nitrosomonas strains. luminescence was dependent on the ph of the medium and the concentration of the substrate ammonium chloride. moreover, the luminescence of the transconjugants was reduced immediately by micromolar concentrations of nitrapyrin and allylthiourea, which are s ... | 1999 | 10398751 |
| feasibility of bioremediation of trichloroethylene contaminated sites by nitrifying bacteria through cometabolism with ammonia. | the autotrophic ammonia-oxidizing bacteria (nitrosomonas sp.) are able to dechlorinate trichloroethylene (tce) through cometabolism using ammonia (nh(3)) as a growth substrate. cometabolic kinetics models suggest that tce is a potent competitive inhibitor of nh(3) oxidation because it competes with nh(3) for oxidation by the enzyme of ammonia monooxygenase (amo). in this study, an enriched culture of nitrifying bacteria was used to investigate the efficiencies of cometabolism of tce by amo. in a ... | 1999 | 10502610 |
| comparison of nitrosospira strains isolated from terrestrial environments. | most of our knowledge about the physiology of ammonia-oxidizing bacteria is based on experiments with nitrosomonas europaea, which appears to be less ubiquitous than nitrosospira. we have isolated nitrosospiras from widely different environments and compared their specific growth rate, substrate affinity, urease activity, temperature response, ph tolerance and cell morphology. two of the strains had a variable morphology: the spirals were less tightly coiled than the classical nitrosospira type ... | 1999 | 10508942 |
| an evaluated improvement of the extinction dilution method for isolation of ammonia-oxidizing bacteria. | an improved method for isolation of ammonia-oxidizing bacteria (aob) by the extinction dilution technique is described. it is important to prevent the growth of heterotrophic organisms, which may easily outnumber the aob in mixed cultures. this was achieved by careful elimination of c sources in the medium and by sealing the cultures from contact with the atmosphere, thus excluding air-borne, volatile compounds which support growth of heterotrophs. the sealing of the cultures reduced the number ... | 1999 | 10579504 |
| nitrogen removal reactor using packed gel envelopes containing nitrosomonas europaea and paracoccus denitrificans. | packed gel envelopes were constructed as simple, compact reactors for removing nitrogen from wastewater. each packed gel envelope consisted of two plate gels with a spacer in between. nitrosomonas europaea and paracoccus denitrificans were co-immobilized in the plate gels, and ethanol, serving as an electron donor for denitrification, was injected into the internal spaces of the envelopes. the external surfaces of the envelopes were in contact with ammonia-containing wastewater; the n. europaea ... | 2000 | 10581438 |
| heme packing motifs revealed by the crystal structure of the tetra-heme cytochrome c554 from nitrosomonas europaea. | cytochrome c554 (cyt c554), a tetra-heme cytochrome from nitrosomonas europaea, is an essential component in the biological nitrification pathway. in n. europaea, ammonia is converted to hydroxylamine, which is then oxidized to nitrite by hydroxylamine oxidoreductase (hao). cyt c554 functions in the latter process by accepting pairs of electrons from hao and transferring them to a cytochrome acceptor. the crystal structure of cyt c554 at 2.6 a resolution shows a predominantly alpha-helical prote ... | 1998 | 9808046 |
| rflp of rrna genes and sequencing of the 16s-23s rdna intergenic spacer region of ammonia-oxidizing bacteria: a phylogenetic approach. | it has been established that 16s rrna gene-based phylogeny gives a low resolution between members of the chemoautotrophic ammonia-oxidizing bacteria (aob) belonging to the beta-subclass of the proteobacteria. in this study, 12 isolates of aob were ribotyped, and the sequences of the 16s-23s rdna intergenic spacer region (isr) were determined and used in a phylogenetic study. 16s and 23s rdna ribotyping revealed that the aob studied contain only one rrn operon per genome, in contrast to most bact ... | 1999 | 10028253 |
| taxon-specific content of oligonucleotide triplets in 16s rrnas of anoxygenic phototrophic and nitrifying bacteria. | theoretical evaluation of the content of oligonucleotide triplets aaa, ccc, and uau in 16s rrnas of anoxygenic phototrophic bacteria (genera chlorobium; chloroflexus; chromatium: rhodopseudomonas) and nitrifying bacteria (genera nitrosococcus, nitrosomonas, nitrosolobus, nitrosovibrio, nitrospira, nitrospina, nitrobacter) showed that the number of the aaa, ccc or uau triplets in 16s rrnas specifically corresponds to the genus and species of bacteria. the ratio of aaa and ccc triplet numbers in t ... | 1999 | 10049622 |
| diversity and distribution of dna sequences with affinity to ammonia-oxidizing bacteria of the beta subdivision of the class proteobacteria in the arctic ocean. | the spatial distribution and diversity of ammonia-oxidizing bacteria of the beta subdivision of the class proteobacteria (hereinafter referred to as ammonia oxidizers) in the arctic ocean were determined. the presence of ammonia oxidizers was detected by pcr amplification of 16s rrna genes using a primer set specific for this group of organisms (nita and nitb, which amplifies a 1.1-kb fragment between positions 137 and 1234, corresponding to escherichia coli 16s rdna numbering). we analyzed 246 ... | 2000 | 10788367 |
| involvement of a novel hydroxylamine oxidoreductase in anaerobic ammonium oxidation. | in this study a novel hydroxylamine oxidoreductase (hao) was purified and characterized from an anaerobic ammonium-oxidizing (anammox) enrichment culture. the enzyme, which constituted about 9% of the protein mass in the soluble fraction of the cell extract, was able to oxidize hydroxylamine and hydrazine. when phenazine methosulfate and methylthiazolyltetrazolium bromide were used as electron acceptors, a v(max) [21 and 1.1 micromol min(-)(1) (mg of protein)(-)(1)] and k(m) (26 and 18 microm) f ... | 2000 | 10820012 |
| new insights into methyl bromide cooxidation by nitrosomonas europaea obtained by experimenting with moderately low density cell suspensions. | we examined the rates and sustainability of methyl bromide (mebr) oxidation in moderately low density cell suspensions ( approximately 6 x 10(7) cells ml(-1)) of the nh(3)-oxidizing bacterium nitrosomonas europaea. in the presence of 10 mm nh(4)(+) and 0.44, 0. 22, and 0.11 mm mebr, the initial rates of mebr oxidation were sustained for 12, 12, and 24 h, respectively, despite the fact that only 10% of the nh(4)(+), 18% of the nh(4)(+), and 35% of the nh(4)(+), respectively, were consumed. althou ... | 2000 | 10877761 |
| molecular evidence for genus level diversity of bacteria capable of catalyzing anaerobic ammonium oxidation. | recently, a bacterium capable to oxidize ammonium anaerobically at a high rate was identified as novel member of the planctomycetales (strous, m., fuersi, j. a., kramer, e. h. m., logemann, s., muyzer, g., van de pas-schoonen, k. t., webb, r. i., kufnen, j. g., and jetten, m. s. m.: nature 400, 446-449, 1999). here we investigated the microbial community structure of a trickling filter biofilm with a high anaerobic ammonium oxidation activity. fluorescence in situ hybridization (fish) with a set ... | 2000 | 10879983 |
| phylogenetic analysis of rhizosphere-associated beta-subclass proteobacterial ammonia oxidizers in a municipal wastewater treatment plant based on rhizoremediation technology. | in wastewater treatment plants based on the rhizosphere zone (rhizoremediation technology), ammonia-oxidizing bacteria (aob) play an important role in the removal of fixed nitrogen. however, the diversity of these bacteria in rhizoremediation wastewater treatment plants is largely unknown. we employed direct pcr amplification and cloning of 16s rrna genes to determine the phylogenetic affiliation of aob occurring in root and soil samples of a wastewater treatment plant (merzdorf plant, brandenbu ... | 2000 | 10886611 |
| kinetic characterization of the inactivation of ammonia monooxygenase in nitrosomonas europaea by alkyne, aniline and cyclopropane derivatives. | the kinetic mechanisms of seven inactivators of ammonia oxidation activity in cells of the nitrifying bacterium, nitrosomonas europaea were investigated. the effects of the inactivators were specific for ammonia monooxygenase (amo) which oxidizes ammonia to hydroxylamine. the aniline derivatives, 1,3-phenylenediamine and p-anisidine, were potent inactivators of amo while other derivatives were ineffective as inactivators. two cyclopropane derivatives, 1, 2-dimethylcyclopropane and cyclopropyl br ... | 1998 | 9858770 |
| identification of major subgroups of ammonia-oxidizing bacteria in environmental samples by t-rflp analysis of amoa pcr products. | a cloning-independent method based on t-rflp (terminal restriction fragment length polymorphism) analysis of amoa pcr products was developed to identify major subgroups of autotrophic ammonia oxidizers of the beta-subclass of the class proteobacteria in total community dna. based on a database of 28 partial gene sequences encoding the active-site polypeptide of ammonia monooxygenase (amoa), defined lengths of terminal restriction fragments (= operational taxonomic units, otus) of amoa were predi ... | 2000 | 10670766 |
| biotreatment of h2s- and nh3-containing waste gases by co-immobilized cells biofilter. | gas mixture of h2s and nh3 in this study has been the focus in the research area concerning gases generated from the animal husbandry and the anaerobic wastewater lagoons used for their treatment. a specific microflora (mixture of thiobacillus thioparus ch11 for h2s and nitrosomonas europaea for nh3) was immobilized with ca-alginate and packed inside a glass column to decompose h2s and nh3. the biofilter packed with co-immobilized cells was continuously supplied with h2s and nh3 gas mixtures of ... | 2000 | 11057594 |
| 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 |
| 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 |