| [short-cut/complete nitrification and denitrification in a pilot-scale plant treating actual domestic wastewater]. | it is realized short-cut nitrification and denitrification in an a/o pilot-scale plant treating actual domestic wastewater controlling do concentration (0.5 mg/l) in low level at normal temperature, the average nitrite accumulation rate reached 85 % or above. three operational modes: low do short-cut nitrification and denitrification (mode 1), low do complete nitrification and denitrification (mode 2) and high do complete nitrification and denitrification (mode 3) were briefly compared, based on ... | 2006 | 17304844 |
| rna microarray for estimating relative abundance of 16s rrna in microbial communities. | we developed an rna microarray protocol in which total rna from a microbial community was attached to a slide glass, and rrna was detected by fluorescently labeled oligonucleotide probes. the rna microarray requires only 4 h for hybridization and enables double staining and estimating relative abundance of rrna. | 2007 | 17320226 |
| development of high-rate anaerobic ammonium-oxidizing (anammox) biofilm reactors. | to promptly establish anaerobic ammonium oxidation (anammox) reactors, appropriate seeding sludge with high abundance and activity of anammox bacteria was selected by quantifying 16s rrna gene copy numbers of anammox bacteria by real-time quantitative pcr (rtq-pcr) and batch culture experiments. the selected sludge was then inoculated into up-flow fixed-bed biofilm column reactors with nonwoven fabric sheets as biomass carrier and the reactor performances were monitored over 1 year. the anammox ... | 2007 | 17350073 |
| identification of nitrifiers in a full-scale biological treatment system using fluorescent in situ hybridization. | diversity of nitrifying bacterial population was investigated in sludge samples taken from a full-scale biological wastewater treatment plant (wwtp) treating domestic wastewater by fluorescent in situ hybridization (fish) during seasonal operation. duplicate grab samples were collected in march 2003, june 2003, december 2003 and may 2004 from the aerobic tank of the treatment plant. fish results were interpreted with system performance in terms of bod5, tkn and no3-n removals and also with opera ... | 2007 | 17365322 |
| global transcriptional response of nitrosomonas europaea to chloroform and chloromethane. | upon exposure of nitrosomonas europaea to chloroform (7 microm, 1 h), transcripts for 175 of 2,460 genes were found at higher levels in treated cells than in untreated cells and transcripts for 501 genes were found at lower levels. with chloromethane (3.2 mm, 1 h), transcripts for 67 genes were at higher levels and transcripts for 148 genes were at lower levels. transcripts for 37 genes were at higher levels following both treatments and included genes for heat shock proteins, sigma-factors of t ... | 2007 | 17369330 |
| transcription of all amoc copies is associated with recovery of nitrosomonas europaea from ammonia starvation. | the chemolithotrophic ammonia-oxidizing bacterium nitrosomonas europaea is known to be highly resistant to starvation conditions. the transcriptional response of n. europaea to ammonia addition following short- and long-term starvation was examined by primer extension and s1 nuclease protection analyses of genes encoding enzymes for ammonia oxidation (amocab operons) and co(2) fixation (cbbls), a third, lone copy of amoc (amoc(3)), and two representative housekeeping genes (glya and rpsj). prime ... | 2007 | 17384196 |
| two-stage biofilter for effective nh3 removal from waste gases containing high concentrations of h2s. | a high h2s concentration inhibits nitrification when h2s and nh3 are simultaneously treated in a single biofilter. to improve nh3 removal from waste gases containing concentrated h2s, a two-stage biofilter was designed to solve the problem. in this study, the first biofilter, inoculated with thiobacillus thioparus, was intended mainly to remove h2s and to reduce the effect of h2s concentration on nitrification in the second biofilter, and the second biofilter, inoculated with nitrosomonas europa ... | 2007 | 17385601 |
| effects of ammonium and nitrite on communities and populations of ammonia-oxidizing bacteria in laboratory-scale continuous-flow reactors. | this study investigated the effects of ammonium and nitrite on ammonia-oxidizing bacteria (aob) from an activated sludge process in laboratory-scale continuous-flow reactors. aob communities were analyzed using specific pcr followed by denaturing gel gradient electrophoresis, cloning and sequencing of the 16s rrna gene, and aob populations were quantified using real-time pcr. to study the effect of ammonium, activated sludge from a sewage treatment system was enriched in four reactors receiving ... | 2007 | 17391333 |
| characterization of two ammonia-oxidizing bacteria isolated from reactors operated with low dissolved oxygen concentrations. | to obtain ammonia-oxidizing bacterial (aob) strains inhabiting low dissolved oxygen (do) environments and to characterize them to better understand their function and ecology. | 2007 | 17448175 |
| use of real-time pcr to examine the relationship between ammonia oxidizing bacterial populations and nitrogen removal efficiency in a small decentralized treatment system 'johkasou'. | the aim of this study was to examine the relationship between ammonia oxidizing bacterial populations and biological nitrogen removal in a small on-site domestic wastewater treatment system "johkasou". the population dynamics of ammonia oxidizing bacteria (aob) in six full-scale advanced johkasous was surveyed using real-time pcr assay over a period of one year. these johkasous were selected to compare the aob populations in different treatment performance. when the effluent nh4-n concentration ... | 2007 | 17506439 |
| the impact of genome analyses on our understanding of ammonia-oxidizing bacteria. | the availability of whole-genome sequences for ammonia-oxidizing bacteria (aob) has led to dramatic increases in our understanding of these environmentally important microorganisms. their genomes are smaller than many other members of the proteobacteria and may indicate genome reductions consistent with their limited lifestyle. the genomes have a surprising level of gene repetition including genes for ammonia catabolism, iron acquisition, and insertion sequences. the gene profiles reveal limited ... | 2007 | 17506671 |
| in situ activity and spatial organization of anaerobic ammonium-oxidizing (anammox) bacteria in biofilms. | we investigated autotrophic anaerobic ammonium-oxidizing (anammox) biofilms for their spatial organization, community composition, and in situ activities by using molecular biological techniques combined with microelectrodes. results of phylogenetic analysis and fluorescence in situ hybridization (fish) revealed that "brocadia"-like anammox bacteria that hybridized with the amx820 probe dominated, with 60 to 92% of total bacteria in the upper part (<1,000 microm) of the biofilm, where high anamm ... | 2007 | 17526785 |
| role of nitrite reductase in the ammonia-oxidizing pathway of nitrosomonas europaea. | metabolism of ammonia (nh(3)) and hydroxylamine (nh(2)oh) by wild-type and a nitrite reductase (nirk) deficient mutant of nitrosomonas europaea was investigated to clarify the role of nirk in the nh(3) oxidation pathway. nirk-deficient n. europaea grew more slowly, consumed less nh(3), had a lower rate of nitrite (no(2) (-)) production, and a significantly higher rate of nitrous oxide (n(2)o) production than the wild-type when incubated with nh(3) under high o(2) tension. in incubations with nh( ... | 2007 | 17541778 |
| a one-stage system with partial nitritation and anammox processes in the moving-bed biofilm reactor. | the ability of bacterial cultures to create biofilm brings a possibility to enhance biological wastewater treatment efficiency. moreover, the ability of anammox and nitrosomonas species to grow within the same biofilm layer enabled a one-stage system for nitrogen removal to be designed. such a system, with kaldnes rings as carriers for biofilm growth, was tested in a technical pilot plant scale (2.1 m(3)) at the himmerfjärden waste water treatment plant (wwtp) in the stockholm region. the system ... | 2007 | 17546965 |
| investigation of microbial communities on reverse osmosis membranes used for process water production. | in the present study, the diversity and the phylogenetic affiliation of bacteria in a biofouling layer on reverse osmosis (ro) membranes were determined. fresh surface water was used as a feed in a membrane-based water purification process. total dna was extracted from attached cells from feed spacer, ro membrane and product spacer. universal primers were used to amplify the bacterial 16s rrna genes. the biofilm community was analysed by 16s rrna-gene-targeted denaturing gradient gel electrophor ... | 2007 | 17546985 |
| changes in ammonia oxidiser population during transition to low ph in a biofilm reactor starting with nitrosomonas europaea. | recent experiments in our laboratory using both biofilm and suspended biomass reactors have demonstrated high rate nitrification at low ph with known autotrophic nitrifying bacteria originating from wastewater treatment plants refuting previous assumptions that nitrification is significantly inhibited at low ph. since much of the earlier microbiological work regarding ammonia oxidising bacteria (aob) physiology was carried out using nitrosomonas europaea, this model bacterium's capability for hi ... | 2007 | 17547006 |
| [comparison of nitrifying populations between a lab-scale system and an industrial system treating coking wastewater]. | molecular analysis of community structure can help diagnose problems in malfunctioning full-scale wastewater treatment system. a lab-scale a1-a2-o fixed biofilm system with highly efficient nitrification (nh3-n removal at 95. 2%) was set up as a reference for an industrial system with poor performance of nitrification (nh3-n removal efficiency at -106%) for treating coking wastewater. composition of nitrifying bacteria of biofilm samples in aerobic reactors of the two systems was compared by 16s ... | 2007 | 17552239 |
| pcr profiling of ammonia-oxidizer communities in acidic soils subjected to nitrogen and sulphur deposition. | communities of ammonia-oxidizing bacteria (aob) were characterized in two acidic soil sites experimentally subjected to varying levels of nitrogen and sulphur deposition. the sites were an acidic spruce forest soil in deepsyke, southern scotland, with low background deposition, and a nitrogen-saturated upland grass heath in pwllpeiran, north wales. betaproteobacterial ammonia-oxidizer 16s rrna and ammonia monooxygenase (amoa) genes were analysed by cloning, sequencing and denaturing gradient gel ... | 2007 | 17573939 |
| the crystal structure of cytochrome p460 of nitrosomonas europaea reveals a novel cytochrome fold and heme-protein cross-link. | we have determined the 1.8 a x-ray crystal structure of a monoheme c-type cytochrome, cytochrome p460, from nitrosomonas europea. the chromophore possesses unusual spectral properties analogous to those of the catalytic heme p460 of hydroxylamine oxidoreductase (hao), the only known heme in biology to withdraw electrons from an iron-coordinated substrate. the analysis reveals a homodimeric structure and elucidates a new c-type cytochrome fold that is predominantly beta-sheet. in addition to the ... | 2007 | 17583915 |
| crystal structures of tm0549 and ne1324--two orthologs of e. coli ahas isozyme iii small regulatory subunit. | crystal structures of two orthologs of the regulatory subunit of acetohydroxyacid synthase iii (ahas, ec 2.2.1.6) from thermotoga maritima (tm0549) and nitrosomonas europea (ne1324) were determined by single-wavelength anomalous diffraction methods with the use of selenomethionine derivatives at 2.3 a and 2.5 a, respectively. tm0549 and ne1324 share the same fold, and in both proteins the polypeptide chain contains two separate domains of a similar size. each protein contains a c-terminal domain ... | 2007 | 17586771 |
| functional and physiological evidence for a rhesus-type ammonia transporter in nitrosomonas europaea. | ammonium transporters form a conserved family of transport proteins and are widely distributed among all domains of life. the genome of nitrosomonas europaea codes for a single gene (rh1) that belongs to the family of the amt/rh ammonium transporters. for the first time, this study provides functional and physiological evidence for a rhesus-type ammonia transporter in bacteria (n. europaea). the methylammonium (ma) transport activity of n. europaea correlated with the rh1 expression. the k(m) va ... | 2007 | 17608700 |
| phylogenetic diversity and the structural basis of substrate specificity in the beta/alpha-barrel fold basic amino acid decarboxylases. | the beta/alpha-barrel fold type basic amino acid decarboxylases include eukaryotic ornithine decarboxylases (odc) and bacterial and plant enzymes with activity on l-arginine and meso-diaminopimelate. these enzymes catalyze essential steps in polyamine and lysine biosynthesis. phylogenetic analysis suggests that diverse bacterial species also contain odc-like enzymes from this fold type. however, in comparison with the eukaryotic odcs, amino acid differences were identified in the sequence of the ... | 2007 | 17626020 |
| molecular analysis of temporal changes of a bacterial community structure in activated sludge using denaturing gradient gel electrophoresis (dgge) and fluorescent in situ hybridization (fish). | wastewater treatment based on activated sludge is known to be one of the most effective and popular wastewater purification methods. an estimation of microbial community variability in activated sludge allows us to observe the correlation between a particular bacterial group's appearance and the effectiveness of the removal of chemical substances. this research is focused on microbial community temporal changes in membrane bioreactors treating wastes containing a high level of ammonia nitrogen. ... | 2007 | 17650682 |
| effects of environmental conditions on the nitrifying population dynamics in a pilot wastewater treatment plant. | the effect of environmental conditions, especially ammonium concentration, on community composition and nitrification activity of nitrifying bacterial biofilms in a pilot wastewater treatment plant was examined. a decreasing ammonium gradient was created when four aerated tanks with suspended carrier material were serially fed with wastewater. community composition was analysed using fluorescence in situ hybridization (fish) probes as well as partial 16s rrna and amoa gene analysis using polymer ... | 2007 | 17686020 |
| diversity and abundance of aerobic and anaerobic ammonium-oxidizing bacteria in freshwater sediments of the xinyi river (china). | here we report on the biodiversity and abundance of aerobic and anaerobic ammonium-oxidizing bacteria in sediment samples from the xinyi river, jinagsu province (china). the biodiversity of aerobic ammonium-oxidizing bacteria in the sediment was assessed using the amoa gene as functional marker. the retrieved amoa clones were affiliated to environmental sequences from freshwater habitats. the closest cultivated relative was nitrosomonas urea. anaerobic ammonium-oxidizing (anammox) bacteria were ... | 2007 | 17686033 |
| effect of mean cell residence time on the performance and microbial diversity of pre-denitrification submerged membrane bioreactors. | the effect of mean cell residence time (mcrt) (5, 8.3, 16.7, and 33.3d) on domestic wastewater treatment performance had been investigated using four bench-scale pre-denitrification submerged membrane bioreactors (mbr) operated in parallel. the 33.3-d mcrt mbr had the lowest microbial activities in terms of specific oxygen uptake rate, specific denitrification rate and observed sludge yield. excellent cod removal efficiency (more than 95%) and nitrification (more than 97%) were observed in all t ... | 2008 | 17714756 |
| the isolation of nitrosomonas and nitrobacter by the single cell technique. | | 1930 | 17799073 |
| diversity of ammonia oxidising bacteria in a vertical flow constructed wetland. | vertical flow constructed wetlands (vfcws) with intermittent loading are very suitable for nitrification. ammonia oxidising bacteria (aob) are the limiting step of nitration. therefore the aob community of a full-scale vfcw, receiving municipal wastewater, was investigated within this study. the diversity of the functional gene encoding the alpha-subunit of the ammonia monooxygenase (amoa), present only in aob, was assessed by denaturing gradient gel electrophoresis (dgge). only very few amoa se ... | 2007 | 17802861 |
| nitrite-oxidizing bacteria guild ecology associated with nitrification failure in a continuous-flow reactor. | nitrification is an important process for nitrogen removal in many wastewater treatment plants, which requires the mutualistic oxidation of ammonia to nitrate by ammonia-oxidizing bacteria (aob) and nitrite-oxidizing bacteria (nob). however, this process can be quite unpredictable because both guilds are conditionally sensitive to small changes in operating conditions. here, dynamics are examined within the nob guild in two parallel chemostats operated at low and high dilution rates (0.10 and 0. ... | 2007 | 17868364 |
| limitations of the use of group-specific primers in real-time pcr as appear from quantitative analyses of closely related ammonia-oxidising species. | to study the ecology of ammonia-oxidising bacteria (aob), quantitative techniques are essential. real-time pcr assays based on the 16s rrna or on the structural amoa gene are routinely used. the cto primer set rooted on the 16s rrna gene has a number of mismatches with some of the cultures of aob. to examine if these mismatches have an effect on the outcome of real-time pcr assays, the assay was tested with dna from a number of closely related isolates of aob. standard curves of known amounts of ... | 2008 | 17889247 |
| composition and activity of beta-proteobacteria ammonia-oxidizing communities associated with intertidal rocky biofilms and sediments of the douro river estuary, portugal. | to characterize the phylogenetic composition of ammonia-oxidizing bacteria (aob) of the beta-subclass of the class proteobacteria in intertidal sediment and rocky biofilms of the douro estuary, and evaluate relationships with environmental variables and n-biogeochemistry. | 2007 | 17897228 |
| evolution and functional characterization of the rh50 gene from the ammonia-oxidizing bacterium nitrosomonas europaea. | the family of ammonia and ammonium channel proteins comprises the amt proteins, which are present in all three domains of life with the notable exception of vertebrates, and the homologous rh proteins (rh50 and rh30) that have been described thus far only in eukaryotes. the existence of an rh50 gene in bacteria was first revealed by the genome sequencing of the ammonia-oxidizing bacterium nitrosomonas europaea. here we have used a phylogenetic approach to study the evolution of the n. europaea r ... | 2007 | 17921289 |
| free ammonia and free nitrous acid inhibition on the anabolic and catabolic processes of nitrosomonas and nitrobacter. | the inhibitory effects of free ammonia (fa) and free nitrous acid (fna) on the catabolic and anabolic processes of nitrosomonas and nitrobacter were investigated using a method that allows decoupling the growth and energy generation processes. lab-scale sequencing batch reactors (sbrs) were operated for the enrichment of nitrosomonas and nitrobacter. fluorescent in-situ hybridization (fish) analysis showed that the reactors were 82% and 73% enriched with nitrosomonas and nitrobacter, respectivel ... | 2007 | 17951872 |
| effects of substratum on the diversity and stability of ammonia-oxidizing communities in a constructed wetland used for wastewater treatment. | to study the relationship between the nature of the substratum and the diversity and stability of the ammonia-oxidizing microbial community in a constructed wetland for the treatment of wastewaters. | 2007 | 17953555 |
| analysis of ammonia loss mechanisms in microbial fuel cells treating animal wastewater. | ammonia losses during swine wastewater treatment were examined using single- and two-chambered microbial fuel cells (mfcs). ammonia removal was 60% over 5 days for a single-chamber mfc with the cathode exposed to air (air-cathode), versus 69% over 13 days from the anode chamber in a two-chamber mfc with a ferricyanide catholyte. in both types of systems, ammonia losses were accelerated with electricity generation. for the air-cathode system, our results suggest that nitrogen losses during electr ... | 2008 | 17972328 |
| [nitrification performance and microbial community analysis in carbon membrane-aerated biofilm reactor]. | a carbon membrane-aerated biofilm reactor was developed to treat nitrogenous inorganic wastewater. influent nh; -n concentrations and hrt were changed to investigate nitrification performance of reactor,oxygen utilization and nh4+ -n's removal loading. biofilm's surface characteristics and dominant bacteria of nitrifier were analyzed. the results show that under the conditions of intra-membrane pressure of 0.017 mpa, influent nh4+ -n of 50 mg/l and hrt of 8 h nh4+ -n removal efficiency reaches 9 ... | 2007 | 17990569 |
| whole-genome analysis of the ammonia-oxidizing bacterium, nitrosomonas eutropha c91: implications for niche adaptation. | analysis of the structure and inventory of the genome of nitrosomonas eutropha c91 revealed distinctive features that may explain the adaptation of n. eutropha-like bacteria to n-saturated ecosystems. multiple gene-shuffling events are apparent, including mobilized and replicated transposition, as well as plasmid or phage integration events into the 2.66 mbp chromosome and two plasmids (65 and 56 kbp) of n. eutropha c91. a 117 kbp genomic island encodes multiple genes for heavy metal resistance, ... | 2007 | 17991028 |
| primer and probe sets for group-specific quantification of the genera nitrosomonas and nitrosospira using real-time pcr. | use of quantitative real-time pcr (qpcr) with taqman probes is increasingly popular in various environmental works to detect and quantify a specific microorganism or a group of target microorganism. although many aspects of conducting a qpcr assay have become very easy to perform, a proper design of oligonucleotide sequences comprising primers and a probe is still considered as one of the most important aspects of a qpcr application. this work was conducted to design group specific primer and pr ... | 2008 | 18023051 |
| distribution of nitrosomonas europaea and nitrobacter winogradskyi in an autotrophic nitrifying biofilm reactor as depicted by molecular analyses and mathematical modelling. | the autotrophic two-species biofilm from the packed bed reactor of a life-support system, containing nitrosomonas europaea atcc 19718 and nitrobacter winogradskyi atcc 25391, was analysed after 4.8 years of continuous operation performing complete nitrification. real-time quantitative polymerase chain reaction (q-pcr) was used to quantify n. europaea and n. winogradskyi along the vertical axis of the reactor, revealing a spatial segregation of n. europaea and n. winogradskyi. the main parameters ... | 2008 | 18023467 |
| nitrifier genomics and evolution of the nitrogen cycle. | advances in technology have tremendously increased high throughput whole genome-sequencing efforts, many of which have included prokaryotes that facilitate processes in the extant nitrogen cycle. molecular genetic and evolutionary analyses of these genomes paired with advances in postgenomics, biochemical and physiological experimentation have enabled scientists to reevaluate existing geochemical and oceanographic data for improved characterization of the extant nitrogen cycle as well as its evo ... | 2008 | 18031536 |
| the 1.3-a resolution structure of nitrosomonas europaea rh50 and mechanistic implications for nh3 transport by rhesus family proteins. | the rhesus (rh) proteins are a family of integral membrane proteins found throughout the animal kingdom that also occur in a number of lower eukaryotes. the significance of rh proteins derives from their presence in the human red blood cell membrane, where they constitute the second most important group of antigens used in transfusion medicine after the abo group. rh proteins are related to the ammonium transport (amt) protein family and there is considerable evidence that, like amt proteins, th ... | 2007 | 18032606 |
| structure of the nitrosomonas europaea rh protein. | amt/mep/rh proteins are a family of integral membrane proteins implicated in the transport of nh3, ch(2)nh2, and co2. whereas amt/mep proteins are agreed to transport ammonia (nh3/nh4+), the primary substrate for rh proteins has been controversial. initial studies suggested that rh proteins also transport ammonia, but more recent evidence suggests that they transport co2. here we report the first structure of an rh family member, the rh protein from the chemolithoautotrophic ammonia-oxidizing ba ... | 2007 | 18040042 |
| intensive management affects composition of betaproteobacterial ammonia oxidizers in turfgrass systems. | turfgrass is a highly managed ecosystem subject to frequent fertilization, mowing, irrigation, and application of pesticides. turf management practices may create a perturbed environment for ammonia oxidizers, a key microbial group responsible for nitrification. to elucidate the long-term effects of turf management on these bacteria, we assessed the composition of betaproteobacterial ammonia oxidizers in a chronosequence of turfgrass systems (i.e., 1, 6, 23, and 95 years old) and the adjacent na ... | 2008 | 18040734 |
| determination of growth rate and yield of nitrifying bacteria by measuring carbon dioxide uptake rate. | nitrifier growth parameters--the maximum growth rate (microamax) and yield (ya)--were estimated by measuring the rate of carbon dioxide uptake and additional rates of oxygen uptake and ammonia (or nitrite) use. batch tests in a combined titrimetric and offgas analyzer with enriched nitrobacter and nitrosomonas cultures and an activated sludge sample were performed. the measured microamax values for the nitrobacter and nitrosomonas cultures were 0.67 +/- 0.03 day(-1) and 0.54 +/- 0.09 day(-1), wh ... | 2007 | 18044361 |
| characterization of the ferrioxamine uptake system of nitrosomonas europaea. | the chemolithoautotroph nitrosomonas europaea has two genes predicted to encode outer-membrane (om) ferrioxamine transporters. expression of the ferrioxamine uptake system required induction, as shown by the shorter lag phase in ferrioxamine-containing cultures when ferrioxamine-exposed cells were used as an inoculum. the two om ferrioxamine siderophore transporters encoded by foxa(1) (ne1097) and foxa(2) (ne1088) were produced only in cells grown in fe-limited ferrioxamine-containing medium. th ... | 2007 | 18048911 |
| effect of 3,3',4',5-tetrachlorosalicylanilide on reduction of excess sludge and nitrogen removal in biological wastewater treatment process. | a metabolic uncoupler, 3,3',4',5-tetrachlorosalicylanilide (tcs), was used to reduce excess sludge production in biological wastewater treatment processes. batch experiments confirmed that 0.4 mg/l of tcs reduced the aerobic growth yield of activated sludge by over 60%. however, the growth yield remained virtually constant even at the increased concentrations of tcs when cultivations were carried out under the anoxic condition. reduction of sludge production yield was confirmed in a laboratory-s ... | 2007 | 18051331 |
| molecular and ecological analyses of microbial community structures in biofilms of a full-scale aerated up-flow biobead process. | molecular and cultivation techniques were used to characterize the bacterial communities of biobead reactor biofilms in a sewage treatment plant to which an aerated up-flow biobead process was applied. with this biobead process, the monthly average values of various chemical parameters in the effluent were generally kept under the regulation limits of the effluent quality of the sewage treatment plant during the operation period. most probable number (mpn) analysis revealed that the population o ... | 2007 | 18051756 |
| change of sludge consortium in response to sequential adaptation to benzene, toluene, and o-xylene. | activated sludge was sequentially adapted to benzene, toluene, and o-xylene (btx) to study the effects on the change of microbial community. sludge adapted to btx separately degraded each by various rates in the following order; toluene>o-xylene>benzene. degradation rates were increased after exposure to repeated spikes of substrates. eleven different kinds of sludge were prepared by the combination of btx sequential adaptations. clustering analyses (jaccard, dice, pearson, and cosine product co ... | 2007 | 18092460 |
| nitrosomonas nm143-like ammonia oxidizers and nitrospira marina-like nitrite oxidizers dominate the nitrifier community in a marine aquaculture biofilm. | zero-discharge marine aquaculture systems are an environmentally friendly alternative to conventional aquaculture. in these systems, water is purified and recycled via microbial biofilters. here, quantitative data on nitrifier community structure of a trickling filter biofilm associated with a recirculating marine aquaculture system are presented. repeated rounds of the full-cycle rrna approach were necessary to optimize dna extraction and the probe set for fish to obtain a reliable and comprehe ... | 2008 | 18093145 |
| genome-wide transcriptional responses of nitrosomonas europaea to zinc. | nitrosomonas europaea, a gram-negative obligate chemolithoautotroph, participates in global nitrogen cycling by carrying out nitrification and derives energy for growth through oxidation of ammonia. in this work, the physiological, proteomic, and transcriptional responses of n. europaea to zinc stress were studied. the nitrite production rate and ammonia-dependent oxygen uptake rate of the cells exposed to 3.4 microm zncl2 decreased about 61 and 69% within 30 min, respectively. two proteins were ... | 2008 | 18097650 |
| nitrifying community analysis in a single submerged attached-growth bioreactor for treatment of high-ammonia waste stream. | this study investigated the nitrifying community structure in a single-stage submerged attached-growth bioreactor (sagb) that successfully achieved stable nitrogen removal over nitrite of a high-strength ammonia wastewater. the reactor was operated with intermittent aeration and external carbon addition (methanol). with influent ammonia and total kjeldahl nitrogen ranging from 537 to 968 mg/l and 643 to 1510 mg/l, respectively, 85% nitrogen removal was obtained, and effluent was dominated by nit ... | 2007 | 18198696 |
| microbial community that catalyzes partial nitrification at low oxygen atmosphere as revealed by 16s rrna and amoa genes. | we previously reported that partial nitrification in the down-flow hanging sponge (dhs) system was satisfactorily accomplished under oxygen-limited conditions [chuang et al., water res., 41, 295-302 (2007)]. in this study, we investigated the microbes that are responsible for the partial nitrification in this unique system by 16s rrna- and amoa-based cloning analyses and fluorescence in situ hybridization. microbes related to nitrosomonas species were found to be chiefly responsible for catalyzi ... | 2007 | 18215643 |
| activated sludge operational regime has significant impact on the type of nitrifying community and its nitrification rates. | a nitrifying sequencing batch reactor, operated under alternating anoxic/aerobic conditions achieved twice the nitrification rates of its strictly aerobic counterpart. microbial populations in both reactors were examined with fluorescent in situ hybridization (fish) and kinetic batch studies to determine the effects of ammonium, nitrite, and oxygen. fish revealed a dominance of rapid nitrifiers like nitrosomonas and nitrobacter (79.5% of the nitrifying population) in the alternating reactor, com ... | 2008 | 18222524 |
| isolation of nitrosomonas from rothamsted soil. | | 1949 | 18228808 |
| physiological state, growth mode, and oxidative stress play a role in cd(ii)-mediated inhibition of nitrosomonas europaea 19718. | the goal of this study was to determine the impact of physiological growth states (batch exponential and batch stationary growth) and growth modes (substrate-limited chemostat, substrate-sufficient exponential batch, and substrate-depleted stationary batch growth) on several measures of growth and responses to cd(ii)-mediated inhibition of nitrosomonas europaea strain 19718. the specific oxygen uptake rate (sour) was the most sensitive indicator of inhibition among the different responses analyz ... | 2008 | 18245236 |
| epiphyton as a niche for ammonia-oxidizing bacteria: detailed comparison with benthic and pelagic compartments in shallow freshwater lakes. | next to the benthic and pelagic compartments, the epiphyton of submerged macrophytes may offer an additional niche for ammonia-oxidizing bacteria in shallow freshwater lakes. in this study, we explored the potential activities and community compositions of ammonia-oxidizing bacteria of the epiphytic, benthic, and pelagic compartments of seven shallow freshwater lakes which differed in their trophic status, distribution of submerged macrophytes, and restoration history. pcr-denaturing gradient ge ... | 2008 | 18263748 |
| physiological and phylogenetic study of an ammonium-oxidizing culture at high nitrite concentrations. | oxidation of high-strength ammonium wastewater can lead to exceptionally high nitrite concentrations; therefore, the effect of high nitrite concentration (> 400 mm) was studied using an ammonium-oxidizing enrichment culture in a batch reactor. ammonium was fed to the reactor in portions of 40-150 mm until ammonium oxidation rates decreased and finally stopped. activity was restored by replacing half of the medium, while biomass was retained by a membrane. the ammonium-oxidizing population obtain ... | 2008 | 18289820 |
| molecular analysis of enrichment cultures of ammonia oxidizers from the salar de huasco, a high altitude saline wetland in northern chile. | we analyzed enrichment cultures of ammonia-oxidizing bacteria (aob) collected from different areas of salar de huasco, a high altitude, saline, ph-neutral water body in the chilean altiplano. samples were inoculated into mineral media with 10 mm nh4+ at five different salt concentrations (10, 200, 400, 800 and 1,400 mm nacl). low diversity (up to three phylotypes per enrichment) of beta-aob was detected using 16s rdna and amoa clone libraries. growth of beta-aob was only recorded in a few enrich ... | 2008 | 18305895 |
| population dynamics of ammonia-oxidizing bacteria in an aerated submerged biofilm reactor for micropolluted raw water pretreatment. | population dynamics of ammonia-oxidizing bacteria (aob) in a full-scale aerated submerged biofilm reactor for micropolluted raw water pretreatment was investigated using molecular techniques for a period of 1 year. the ammonia monooxygenase (amoa) gene fragments were amplified from dna and rna extracts of biofilm samples. denaturing gradient gel electrophoresis (dgge) profile based on the amoa messenger rna approach exhibited a more variable pattern of temporal dynamics of aob communities than t ... | 2008 | 18305935 |
| t-rflp detection of nitrifying bacteria in a fluidized bed reactor of achieving simultaneous nitrification-denitrification. | steady simultaneous nitrification-denitrification (snd) was achieved in a fluidized bed reactor (fbr) by the control of do concentration without physical separation of the aerobic and anoxic zones. the performance and composition of nitrifying bacteria were examined in this study. the ammonium removal efficiency was higher than 80% and the do concentration (1-5 mg l(-1)) had little influence on it. more than 50% total nitrogen (tn) removal efficiency was achieved when do was less than 3 mg l(-1) ... | 2008 | 18313099 |
| long-term assessment of nitrification in a full-scale wastewater treatment plant. | in this study, long term nitrification performances and microbial composition in a full-scale oxidation ditch type wastewater treatment plant (wwtp) were monitored and evaluated using different molecular methods; fluorescent in situ hybridization (fish), slot-blot hybridization and quantitative real-time polymerase chain reaction (pcr) method. in situ and membrane hybridization results indicated that nitrosomonas species were identified as the dominant ammonia oxidizing bacteria and nitrospira r ... | 2008 | 18324541 |
| diversity and spatio-temporal distribution of ammonia-oxidizing archaea and bacteria in sediments of the westerschelde estuary. | the diversity and spatio-temporal distribution of ammonia-oxidizing archaea (aoa) and bacteria (aob) were investigated along a salinity gradient in sediments of the westerschelde estuary. sediment samples were collected from three sites with different salinities, and at six time points over the year. denaturing gradient gel electrophoresis of pcr-amplified 16s rrna and amoa gene fragments was used to identify the aoa and aob present. members of the aoa were mainly belonging to the crenarchaeota ... | 2008 | 18336555 |
| abundance and composition of ammonia-oxidizing bacteria and ammonia-oxidizing archaea communities of an alkaline sandy loam. | the abundance and composition of soil ammonia-oxidizing bacteria (aob) and ammonia-oxidizing archaea (aoa) communities under different long-term (17 years) fertilization practices were investigated using real-time polymerase chain reaction and denaturing gradient gel electrophoresis (dgge). a sandy loam with ph (h(2)o) ranging from 8.3 to 8.7 was sampled in years 2006 and 2007, including seven fertilization treatments of control without fertilizers (ck), those with combinations of fertilizer nit ... | 2008 | 18336563 |
| theoretical insight into the hydroxylamine oxidoreductase mechanism. | the multiheme enzyme hydroxylamine oxidoreductase from the autotrophic bacteria nitrosomonas europaea catalyzes the conversion of hydroxylamine to nitrite, with a complicate arrangement of heme groups in three subunits. as a distinctive feature, the protein has a covalent linkage between a tyrosyl residue of one subunit and a meso carbon atom of the heme active site of another. we studied the influence of this bond in the catalysis from a theoretical perspective through electronic structure calc ... | 2008 | 18336913 |
| adhesion characteristics of nitrifying bacteria in activated sludge. | nitrifiers are known to form relatively dense and strong microcolonies in activated sludge flocs, but little is known about their adhesion characteristics and how these are relative to other floc components. the size distribution of ammonia and nitrite-oxidizing bacteria (nitrosomonas oligotropha and nitrospira spp.) in activated sludge from a nutrient removal plant showed that the majority of n. oligotropha cells formed microcolonies with a diameter of 13-22.5 microm, and most nitrospira spp. c ... | 2008 | 18359056 |
| dna microarray mediated transcriptional profiling of nitrosomonas europaea in response to linear alkylbenzene sulfonates. | linear alkylbenzene sulfonates (las) constitute, quantitatively, the most important group of synthetic surfactants used today. we studied the gene expression of nitrosomonas europaea in response to las using a dna microarray because ammonia-oxidizers are thought to be more sensitive to las than other microorganisms. our objective was to elucidate which genes are expressed for n. europaea in response to las exposure. microarray analysis and real-time pcr assay revealed that c. 30 genes were signi ... | 2008 | 18371069 |
| complete genome sequence of nitrosospira multiformis, an ammonia-oxidizing bacterium from the soil environment. | the complete genome of the ammonia-oxidizing bacterium nitrosospira multiformis (atcc 25196(t)) consists of a circular chromosome and three small plasmids totaling 3,234,309 bp and encoding 2,827 putative proteins. of the 2,827 putative proteins, 2,026 proteins have predicted functions and 801 are without conserved functional domains, yet 747 of these have similarity to other predicted proteins in databases. gene homologs from nitrosomonas europaea and nitrosomonas eutropha were the best match f ... | 2008 | 18390676 |
| distinctive microbial ecology and biokinetics of autotrophic ammonia and nitrite oxidation in a partial nitrification bioreactor. | biological nitrogen removal (bnr) based on partial nitrification and denitrification via nitrite is a cost-effective alternate to conventional nitrification and denitrification (via nitrate). the goal of this study was to investigate the microbial ecology, biokinetics, and stability of partial nitrification. stable long-term partial nitrification resulting in 82.1 +/- 17.2% ammonia oxidation, primarily to nitrite (77.3 +/- 19.5% of the ammonia oxidized) was achieved in a lab-scale bioreactor by ... | 2008 | 18393313 |
| nitric oxide: interaction with the ammonia monooxygenase and regulation of metabolic activities in ammonia oxidizers. | the biological nitrogen cycle is a complex interplay of many microorganisms. in the past, oxidation of the inorganic nitrogen compound ammonia by the ammonia oxidizing bacteria was thought to be restricted to oxic environments, and the metabolic flexibility of these organisms seemed to be limited. the discovery of an anaerobic metabolism in the late 1990s showed that these assumptions are no longer valid. no and no(2) are essential intermediates in ammonia oxidation. both gases have wide-ranging ... | 2008 | 18423214 |
| presence and activity of ammonia-oxidising bacteria detected amongst the overall bacterial diversity along a physico-chemical gradient of a nitrifying wastewater treatment plant. | we wished to discover if we could gain greater insights into how biological treatment plants function by contrasting the presence and activity of the most abundant bacteria in plug flow and completely mixed activated sludge plants. presence was assessed by amplifying 16s rrna gene fragments (using pcr) and activity by amplifying native 16s rrna, using reverse-transcriptase pcr (rt-pcr), using bacteria-specific primers. the amplified sequences were compared using denaturing gradient gel electroph ... | 2008 | 18423799 |
| anaerobic ammonium oxidation by nitrosomonas spp. and anammox bacteria in a sequencing batch reactor. | a sequencing batch reactor (sbr) was inoculated with mixed nitrifying bacteria from an anoxic tank at the conventional activated sludge wastewater treatment plant in nongkhaem, bangkok, thailand. this enriched nitrifying culture was maintained under anaerobic conditions using ammonium (nh(4)(+)) as an electron donor and nitrite (no(2)(-)) as an electron acceptor. autotrophic ammonium oxidizing bacteria survived under these conditions. the enrichment period for anammox culture was over 100 days. ... | 2009 | 18423965 |
| evaluation of oxygen adaptation and identification of functional bacteria composition for anammox consortium in non-woven biological rotating contactor. | in this study, the anammox consortium was found to adapt to the wastewater containing dissolved oxygen (do), as the do was gradually increased. batch tests indicated the maximum aerobic ammonium oxidizing activity of the consortium was 1.38mmolnh4+-n(gvss)(-1)day(-1), which played key roles in the oxygen consumption process; the maximum anaerobic ammonium oxidizing activity was slightly decreased after long-term oxygen exposure, but only from 21.23mmolnh4+-n(gvss)(-1)day(-1) to 20.23mmolnh4+-n(g ... | 2008 | 18439820 |
| [inhibition investigation of aniline on nitrification process in batch and continuous running reactors]. | inhibition effect of aniline on nitrifier was investigated in suspended sludge batch reactors and a three-phase fluidized bed. the tested nitrifier and aniline degradation bacteria were obtained from excess sludge of a treatment plant for aniline wastewater. the results showed that aniline had produced obvious inhibition on nitrifier in suspended sludge batch reactors. barely when aniline concentration was less than 3 mg/l, had nitrifier gradually recovered their ability. but the recovered time ... | 2008 | 18441926 |
| [ammonia oxidation kinetics of ammonia oxidizer mixed culture under the conditions of o2 and trace no2 mixed gasses]. | the kinetics of the no2-dependent ammonia oxidation was developed for ammonia oxidizer mixed culture when there was no molecular oxygen in the batch tests. the kinetics parameters were determined, where the half saturate coefficient of no2 was 0.821 micromol x l(-1), inhibition coefficient of no2 concentration was 1.721 micromol x l(-1), and the maximum ammonia oxidation rate were 0.144 mg x (mg x h)(-1). after adding the volume fraction of o2 was 2% to trace no2, the ammonia oxidation rates inc ... | 2008 | 18441929 |
| long-term storage and subsequent reactivation of aerobic granules. | this study investigated a seven month storage and the subsequent reactivation of aerobic granules. the granule size and structure integrity were remained during storage, whereas some cavities and pleats appeared on the surface and further deteriorated the settleability. along with the reactivation, the physical characteristics and microbial activities of aerobic granules were gradually improved. activities of heterotrophs and nitrifiers can be fully recovered within 16days and 11days, respective ... | 2008 | 18442901 |
| seasonal variation in communities of ammonia-oxidizing bacteria based on polymerase chain reaction - denaturing gradient gel electrophoresis in a biofilm reactor for drinking water pretreatment. | the diversity and variation of total and active ammonia-oxidizing bacteria in a full-scale aerated submerged biofilm reactor for drinking water pretreatment were characterized by clone libraries and denaturing gradient gel electrophoresis (dgge) analysis of 16s rrna and its gene during a whole year. sequences obtained from clone libraries affiliated with the nitrosomonas oligotropha lineage and the nitrosomonas communis lineage. an uncultured subgroup of nitrosomonas communis lineage was also de ... | 2008 | 18449220 |
| monitoring of population shifts in an enriched nitrifying system under gradually increased cadmium loading. | the changes in nitrifying bacterial population under cadmium loading were monitored and evaluated in a laboratory scale continuous-flow enriched nitrification system. for this purpose, the following molecular microbiological methods were used: slot-blot hybridization, denaturing gradient gel electrophoresis (dgge), real-time pcr followed by melting curve analysis, cloning and sequence analysis. the initial cadmium concentration was incrementally increased from 1 to 10mg/l which led to a drop in ... | 2008 | 18462880 |
| savings with upgraded performance through improved activated sludge denitrification in the combined activated sludge-biofilter system of the southpest wastewater treatment plant. | the purpose of the experiments was to increase the rate of activated sludge denitrification in the combined biological treatment system of the southpest wastewater treatment plant in order to gain savings in cost and energy and improve process efficiency. initial profile measurements revealed excess denitrification capacity of the preclarified wastewater. as a consequence, flow of nitrification filter effluent recirculated to the anoxic activated sludge basins was increased from 23,000 m3 d(-1) ... | 2008 | 18469403 |
| niche separation of ammonia-oxidizing bacteria across a tidal freshwater marsh. | like many functional groups or guilds of microorganisms, the group of ammonia-oxidizing bacteria (aob) consists of a number of physiologically different species or lineages. these physiological differences suggest niche differentiation among these bacteria depending on the environmental conditions. species of aob might be adapted to different zones in the flooding gradient of a tidal marsh. this issue has been studied by sampling sediments from different sites and depths within a tidal freshwate ... | 2008 | 18479444 |
| diversity of ammonium-oxidizing bacteria in a granular sludge anaerobic ammonium-oxidizing (anammox) reactor. | the ammonium-oxidizing microbial community was investigated in a granular sludge anaerobic ammonium-oxidizing (anammox) reactor that was operated for about 1 year with high anaerobic ammonium oxidation activity (up to 0.8 kg nh(4)(+)-n m(-3) day(-1)). a planctomycetales-specific 16s rrna gene library was constructed to analyse the diversity of the anaerobic ammonium-oxidizing bacteria (anaob). most of the specifically amplified sequences (15/16) were similar to each other (> 99%) but were distan ... | 2008 | 18479446 |
| membrane tetraheme cytochrome c(m552) of the ammonia-oxidizing nitrosomonas europaea: a ubiquinone reductase. | cytochrome c(m552) (cyt c(m552)) from the ammonia-oxidizing nitrosomonas europaea is encoded by the cycb gene, which is preceded in a gene cluster by three genes encoding proteins involved in the oxidation of hydroxylamine: hao, hydroxylamine oxidoreductase; orf2, a putative membrane protein; cyca, cyt c(554). by amino acid sequence alignment of the core tetraheme domain, cyt c(m552) belongs to the napc/torc family of tetra- or pentaheme cytochrome c species involved in electron transport from m ... | 2008 | 18505274 |
| immobilization of nitrosomonas europaea cells with polyelectrolyte complex. | cell immobilization with polyelectrolyte complex prepared from strongly polyacidic and polybasic ions was investigated for cells from nitrosomonas europaea (atcc 25978). trimethylammonium glycol chitosan (tgci) and potassium poly(vinyl-alcohol) sulfate (kpvs) were used. the immobilization was carried out by directly mixing both polymer solutions with the culture broth: an excess of tgci was first added to the culture broth to aggregate the cells, and then kpvs was added to form the complex with ... | 1982 | 18546459 |
| kinetic and product distribution analysis of no* reductase activity in nitrosomonas europaea hydroxylamine oxidoreductase. | hydroxylamine oxidoreductase (hao) from the ammonia-oxidizing bacterium nitrosomonas europaea normally catalyzes the four-electron oxidation of hydroxylamine to nitrite, which is the second step in ammonia-dependent respiration. here we show that, in the presence of methyl viologen monocation radical (mv(red)), hao can catalyze the reduction of nitric oxide to ammonia. the process is analogous to that catalyzed by cytochrome c nitrite reductase, an enzyme found in some bacteria that use nitrite ... | 2008 | 18553112 |
| effects of bacteria on nitrogen and phosphorus release from river sediment. | to better understand the mechanisms of eutrophication, we addressed the microbial processes that influence many key aspects of water-sediment systems. in this study, a large column experiment was conducted for 30 d. along the column, solution samples were collected at different locations at different time. the samples were analyzed for physical, chemical, and biological properties of the sediment and overlying water. the results showed that the amount of nitrogen transforming bacteria was higher ... | 2008 | 18575123 |
| simultaneously occurring nitrification and denitrification under oxygen gradient by polyelectrolyte complex-coimmobilized nitrosomonas europaea and paracoccus denitrificans cells. | | 1988 | 18584619 |
| analysis of nitrifying bacterial communities in aerobic biofilm reactors with different do conditions using molecular techniques. | in order to assess the relationship between the dissolved oxygen (do) concentration and the characteristics of nitrifying bacterial communities in an aerobic biofilm reactor, molecular techniques including denaturing gradient gel electrophoresis (dgge)/cloning based on pcr targeting 16s rrna and the amoa gene and fluorescence in situ hybridisation (fish) were conducted. the d-1, d-2, d-3 and d-4 reactors with different do concentrations (1, 3, 5 and 7 mg/l, respectively) were set up in the therm ... | 2008 | 18587175 |
| physiological and transcriptional responses of nitrosomonas europaea to toluene and benzene inhibition. | ammonia oxidizing bacteria (aob) are inhibited by many compounds found in wastewater treatment plant (wwtp) influent, including aromatic hydrocarbons. the detection of "sentinel genes" to identify the presence of aromatic hydrocarbons could be useful to wwtp operators. in this study, the transcriptomic responses of nitrosomonas europaea during the cometabolism of benzene to phenol and toluene to benzyl alcohol and benzaldehyde were evaluated using whole genome affymetrix microarrays and qrt-pcr. ... | 2008 | 18589971 |
| assessment of the positive effect of salinity on the nitrogen removal performance and microbial composition during the start-up of canon process. | in this study, a non-woven rotating biological contactor reactor was operated for the start-up of completely autotrophic nitrogen removal over nitrite (canon) process. in this perfectly attached growth system, nitrite oxidizing was identified, which interfered with the nitrogen removal performance. batch tests indicated that 10 g nacl per liter salinity was a preferable definite level to stand out ammonium-oxidizing activity and anammox activity, and selectively suppress nitrite-oxidizing activi ... | 2008 | 18592234 |
| dynamic aspects and controllability of the melissa project: a bioregenerative system to provide life support in space. | manmade ecosystems differ from their prototype biosphere by the principle of control. the earth biosphere is sustainable by stochastic control and very large time constants. by contrast, in a closed ecosystem such as the micro-ecological life support system alternative (melissa system) developed by the european space agency for space exploration, a deterministic control is a prerequisite of sustainable existence. melissa is an integrated sum of interconnected biological subsystems. on one hand, ... | 2008 | 18592407 |
| transcription of genes coding for metabolic key functions in nitrosomonas europaea during aerobic and anaerobic growth. | nitrosomonas europaea can grow under conditions of chemolithoautotrophic aerobic (oxygen as oxidant) as well as anaerobic [nitrogen dioxide (no(2)) as oxidant] nitrification or chemoorganotrophic anaerobic pyruvate-dependent denitrification. in this study, the adaptation of the transcription (mrna synthesis/concentration) of n. europaea to aerobic and anaerobic growth conditions was evaluated and the transcription of genes coding for metabolic key functions was analyzed: nitrogen and energy meta ... | 2009 | 18594130 |
| nitrifying genera in activated sludge may influence nitrification rates. | sequencing batch reactors were acclimated under aerobic and alternating anoxic/aerobic conditions. greater nitrification rates in the alternating reactor were investigated by comparing environmental conditions. in the alternating reactor, ph, alkalinity, oxygen, and nitrite were higher at the onset of aerobic nitrification. kinetic studies and batch tests, with biomass developed under aerobic and alternating conditions, revealed that these factors were insufficient to explain the divergent nitri ... | 2008 | 18605378 |
| candidate stress genes of nitrosomonas europaea for monitoring inhibition of nitrification by heavy metals. | heavy metals have been shown to be strong inhibitors of nitrification in wastewater treatment plants. in this research, the effects of cadmium, copper, and mercury on nitrosomonas europaea were studied in quasi-steady-state batch reactors. when cells were exposed to 1 microm cdcl2, 6 microm hgcl2, or 8 microm cucl2, ammonia oxidation rates were decreased by about 90%. whole-genome transcriptional and proteomic responses of n. europaea to cadmium were used to identify heavy metal stress response ... | 2008 | 18606795 |
| co-immobilized nitrosomonas europaea and nitrobacter agilis cells: validation of a dynamic model for simultaneous substrate conversion and growth in kappa-carrageenan gel beads. | a dynamic model for two microbial species immobilized in a gel matrix is presented and validated with experiments. the model characterizes the nitrification of ammonia with nitrosomonas europaea and nitrobacter agilis co-immobilized in k-carrageenan gel beads. the model consists of kinetic equations for the microorganisms and mass transfer equations for the substrates and products inside and outside the gel beads. the model predicts reactor bulk concentrations together with the substrate consump ... | 1994 | 18615529 |
| functional robustness and gene pools of a wastewater nitrification reactor: comparison of dispersed and intact biofilms when stressed by low oxygen and low ph. | the functional robustness of biofilms in a wastewater nitrification reactor, and the gene pools therein, were investigated. nitrosomonas and nitrosospira spp. were present in similar amounts (cloning-sequencing of ammonia-oxidizing bacteria 16s rrna gene), and their estimated abundance (1.1 x 10(9) cells g(-1) carrier material, based on amoa gene real-time pcr) was sufficient to explain the observed nitrification rates. the biofilm also had a diverse community of heterotrophic denitrifying bacte ... | 2008 | 18616585 |
| effects of diffusion limitation on immobilized nitrifying microorganisms at low temperatures. | activation energies of suspended and immobilized nitrifying bacteria were determined and compared to determine if diffusion limitation results in decreased sensitivity for temperature. the activation energy for the respiration activity of suspended nitrosomonas europaea and nitrobacter agilis was found to be 86.4 and 58.4 kj mol(-1), respectively. the activation energy for oxygen diffusion in the support material, kappa-carrageenan, determined from the effect of temperature on the effective diff ... | 1995 | 18623045 |
| a cometabolic kinetics model incoroporating enzyme inhibition, inactivation, and recovery: ii. trichloroethylene degradaation experiments. | a cometabolism enzyme kinetics model has been presented which takes into account changes in bacterial activity associated with enzyme inhibitiion, inactivation, inactivation of enzyme resulting from product toxicty, and respondent synthesis of new enzyme. although this process is inherently unsteady-state, the model assumes that cometabolic degradation of a compound exhibiting product toxicity can be modeled as pseudo-steady-staate under certain conditions. in its simplified from, the model also ... | 1995 | 18623307 |
| steady-state solution of a two-species biofilm problem. | through a thorough investigation of the boundary conditions for a general two-species biofilm model, a simple and fast method for solving the steady-state case is developed and presented. the methods used may be extended to biofilm models in which more than two species are considered. four different sets of boundary conditions are possible for the two-species biofilm model. each set is shown to be asymptotically stable. a biofilm model describing the competition between autotrophic and heterotro ... | 1996 | 18627076 |
| cometabolism of chlorinated solvents by nitrifying bacteria: kinetics, substrate interactions, toxicity effects, and bacterial response. | pure cultures of ammonia-oxidizing bacteria, nitrosomonas europaea, were exposed to trichloroethylene (tce), 1,1-dichloroethylene (1,1-dce), chloroform (cf), 1,2-dichloroethane (1,2-dca), or carbon tetrachloride (ct), in the presence of ammonia, in a quasi-steady-state bioreactor. estimates of enzyme kinetics constants, solvent inactivation constants, and culture recovery constants were obtained by simultaneously fitting three model curves to experimental data using nonlinear optimization techni ... | 1997 | 18636408 |
| dynamics of artificially immobilized nitrosomonas europaea: effect of biomass decay. | the dynamics of growth and death of immobilized nitrosomonas europaea were studied. for this, the death rate of suspended cells was determined in the absence of ammonium or oxygen by following the loss of respiration activity and by fluorescein-diacetate (fda)/lissamine-green staining techniques. the death rates obtained (1.06 x 10(-6) s(-1) or 4.97 x 10(-6) s(-1) in the absence of oxygen or ammonium, respectively) were incorporated in a dynamic growth model and the effects on the performance of ... | 1997 | 18636573 |
| detection, isolation and characterization of a root-exuded compound, methyl 3-(4-hydroxyphenyl) propionate, responsible for biological nitrification inhibition by sorghum (sorghum bicolor). | nitrification results in poor nitrogen (n) recovery and negative environmental impacts in most agricultural systems. some plant species release secondary metabolites from their roots that inhibit nitrification, a phenomenon known as biological nitrification inhibition (bni). here, we attempt to characterize bni in sorghum (sorghum bicolor). in solution culture, the effect of n nutrition and plant age was studied on bni activity from roots. a bioluminescence assay using recombinant nitrosomonas e ... | 2008 | 18657214 |