| a new obligately chemolithoautotrophic, nitrite-oxidizing bacterium, nitrospira moscoviensis sp. nov. and its phylogenetic relationship. | a gram-negative, non-motile, non-marine, nitrite-oxidizing bacterium was isolated from an enrichment culture initiated with a sample from a partially corroded area of an iron pipe of a heating system in moscow, russia. the cells were 0.9-2.2 microns x 0.2-0.4 microns in size. they were helical- to vibroid-shaped and often formed spirals with up to three turns 0.8-1.0 micron in width. the organism possessed an enlarged periplasmic space and lacked intracytoplasmic membranes and carboxysomes. the ... | 1995 | 7646315 |
| 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 |
| isolation and immunocytochemical location of the nitrite-oxidizing system in nitrospira moscoviensis | a membrane-associated nitrite-oxidizing system of nitrospira moscoviensis was isolated from heat-treated membranes. the four major proteins of the enzyme fraction had apparent molecular masses of 130, 62, 46, and 29 kda, respectively. the nitrite-oxidizing activity was dependent on the presence of molybdenum. in contrast to the nitrite oxidoreductase of nitrobacter hamburgensis x14, the activity of the nitrite-oxidizing system of ns. moscoviensis increased when solubilized by heat treatment. ele ... | 1998 | 9477257 |
| microbiology of a nitrite-oxidizing bioreactor. | the microbiology of the biomass from a nitrite-oxidizing sequencing batch reactor (nosbr) fed with an inorganic salts solution and nitrite as the sole energy source that had been operating for 6 months was investigated by microscopy, by culture-dependent methods, and by molecular biological methods, and the seed sludge that was used to inoculate the nosbr was investigated by molecular biological methods. the nosbr sludge comprised a complex and diverse microbial community containing gram-negativ ... | 1998 | 9572966 |
| 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 |
| 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 |
| 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 |
| 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 |
| microscale distribution of populations and activities of nitrosospira and nitrospira spp. along a macroscale gradient in a nitrifying bioreactor: quantification by in situ hybridization and the use of microsensors. | the change of activity and abundance of nitrosospira and nitrospira spp. along a bulk water gradient in a nitrifying fluidized bed reactor was analyzed by a combination of microsensor measurements and fluorescence in situ hybridization. nitrifying bacteria were immobilized in bacterial aggregates that remained in fixed positions within the reactor column due to the flow regimen. nitrification occurred in a narrow zone of 100 to 150 microm on the surface of these aggregates, the same layer that c ... | 1999 | 10427067 |
| identification of nitrite-oxidizing bacteria with monoclonal antibodies recognizing the nitrite oxidoreductase. | immunoblot analyses performed with three monoclonal antibodies (mabs) that recognized the nitrite oxidoreductase (nor) of the genus nitrobacter were used for taxonomic investigations of nitrite oxidizers. we found that these mabs were able to detect the nitrite-oxidizing systems (nos) of the genera nitrospira, nitrococcus, and nitrospina. the mab designated hyb 153-2, which recognized the alpha subunit of the nor (alpha-nor), was specific for species belonging to the genus nitrobacter. in contra ... | 1999 | 10473425 |
| molecular analysis of microbial communities in mobile deltaic muds of southeastern papua new guinea. | a culture-independent examination of microbial diversity in mobile deltaic sediments from the gulf of papua, papua new guinea, was conducted by sequence analysis of 16s rdna clone library. universal small subunit primers were used to amplify dna extracted from the sediment. of 91 clones randomly selected from the library, 33 contained unique non-chimeric sequences. analysis of these unique sequences showed that the majority of them belonged to bacteria (94.5%), with proteobacteria being the domi ... | 2000 | 10967214 |
| application of an amperometric immunosensor for the enumeration of nitrobacter in activated sludge. | a competitive immunosensor using a monoclonal antibody has been developed for the enumeration of nitrobacter in activated sludge and other environmental samples. its cross-reactivity was tested against a number of bacterial strains and isolates. all strains of the nitrite-oxidising genera nitrobacter and nitrococcus reacted strongly with the monoclonal antibody. the nitrite-oxidising nitrospira moscoviensis, as well as the ammonia oxidising bacteria and the heterotrophic bacteria tested, did not ... | 2000 | 11030580 |
| microenvironments and distribution of nitrifying bacteria in a membrane-bound biofilm. | the distribution of nitrifying bacteria of the genera nitrosomonas, nitrosospira, nitrobacter and nitrospira was investigated in a membrane-bound biofilm system with opposed supply of oxygen and ammonium. gradients of oxygen, ph, nitrite and nitrate were determined by means of microsensors while the nitrifying populations along these gradients were identified and quantified using fluorescence in situ hybridization (fish) in combination with confocal laser scanning microscopy. the oxic part of th ... | 2000 | 11214800 |
| community structure and activity dynamics of nitrifying bacteria in a phosphate-removing biofilm. | the microbial community structure and activity dynamics of a phosphate-removing biofilm from a sequencing batch biofilm reactor were investigated with special focus on the nitrifying community. o(2), no(2)(-), and no(3)(-) profiles in the biofilm were measured with microsensors at various times during the nonaerated-aerated reactor cycle. in the aeration period, nitrification was oxygen limited and restricted to the first 200 microm at the biofilm surface. additionally, a delayed onset of nitrif ... | 2001 | 11229931 |
| diversity and seasonal fluctuations of the dominant members of the bacterial soil community in a wheat field as determined by cultivation and molecular methods. | there is a paucity of knowledge on microbial community diversity and naturally occurring seasonal variations in agricultural soil. for this purpose the soil microbial community of a wheat field on an experimental farm in the netherlands was studied by using both cultivation-based and molecule-based methods. samples were taken in the different seasons over a 1-year period. fatty acid-based typing of bacterial isolates obtained via plating revealed a diverse community of mainly gram-positive bacte ... | 2001 | 11319113 |
| phylogenetic structure of unusual aquatic microbial formations in nullarbor caves, australia. | the nature of unusual aquatic microbial formations in flooded passages of cave systems in the nullarbor region of australia was investigated using electron microscopy and dna analysis. the caves are located in a semiarid region but intersect the watertable at depths of approximately 100 m below the surface. throughout submerged portions of the caves divers have noted the presence of unusual microbial formations. these 'microbial mantles' comprise sheets or tongues of mucoid material in which sma ... | 2001 | 11359511 |
| nitrification in sequencing biofilm batch reactors: lessons from molecular approaches. | the nitrifying microbial diversity and population structure of a sequencing biofilm batch reactor receiving sewage with high ammonia and salt concentrations (sbbr 1) was analyzed by the full-cycle rrna approach. the diversity of ammonia-oxidizers in this reactor was additionally investigated using comparative sequence analysis of a gene fragment of the ammonia monooxygenase (amoa), which represents a key enzyme of all ammonia-oxidizers. despite the "extreme" conditions in the reactor, a surprisi ... | 2001 | 11381937 |
| diversity and characterization of sulfate-reducing bacteria in groundwater at a uranium mill tailings site. | microbially mediated reduction and immobilization of u(vi) to u(iv) plays a role in both natural attenuation and accelerated bioremediation of uranium-contaminated sites. to realize bioremediation potential and accurately predict natural attenuation, it is important to first understand the microbial diversity of such sites. in this paper, the distribution of sulfate-reducing bacteria (srb) in contaminated groundwater associated with a uranium mill tailings disposal site at shiprock, n.mex., was ... | 2001 | 11425735 |
| in situ characterization of nitrospira-like nitrite-oxidizing bacteria active in wastewater treatment plants. | uncultivated nitrospira-like bacteria in different biofilm and activated-sludge samples were investigated by cultivation-independent molecular approaches. initially, the phylogenetic affiliation of nitrospira-like bacteria in a nitrifying biofilm was determined by 16s rrna gene sequence analysis. subsequently, a phylogenetic consensus tree of the nitrospira phylum including all publicly available sequences was constructed. this analysis revealed that the genus nitrospira consists of at least fou ... | 2001 | 11679356 |
| ammonia- and nitrite-oxidizing bacterial communities in a pilot-scale chloraminated drinking water distribution system. | nitrification in drinking water distribution systems is a common operational problem for many utilities that use chloramines for secondary disinfection. the diversity of ammonia-oxidizing bacteria (aob) and nitrite-oxidizing bacteria (nob) in the distribution systems of a pilot-scale chloraminated drinking water treatment system was characterized using terminal restriction fragment length polymorphism (t-rflp) analysis and 16s rrna gene (ribosomal dna [rdna]) cloning and sequencing. for ammonia ... | 2002 | 11772611 |
| quantification of nitrosomonas oligotropha-like ammonia-oxidizing bacteria and nitrospira spp. from full-scale wastewater treatment plants by competitive pcr. | utilizing the principle of competitive pcr, we developed two assays to enumerate nitrosomonas oligotropha-like ammonia-oxidizing bacteria and nitrite-oxidizing bacteria belonging to the genus nitrospira: the specificities of two primer sets, which were designed for two target regions, the amoa gene and nitrospira 16s ribosomal dna (rdna), were verified by dna sequencing. both assays were optimized and applied to full-scale, activated sludge wastewater treatment plant (wwtp) samples. if it was as ... | 2002 | 11772633 |
| fatty acid profiles of nitrite-oxidizing bacteria reflect their phylogenetic heterogeneity. | the fatty acid profiles of all described species of the nitrite-oxidizing genera nitrobacter, nitrococcus, nitrospina and nitrospira were analyzed. the four genera had distinct profiles, which can be used for the differentiation and allocation of new isolates to these genera. the genus nitrobacter is characterized by vaccenic acid as the main compound with up to 92% of the fatty acids and the absence of hydroxy fatty acids. the genus nitrococcus showed cis-9-hexadecenoic acid, hexadecanoic acid ... | 2001 | 11822673 |
| the canon system (completely autotrophic nitrogen-removal over nitrite) under ammonium limitation: interaction and competition between three groups of bacteria. | the canon system (completely autotrophic nitrogen removal over nitrite) can potentially remove ammonium from wastewater in a single, oxygen-limited treatment step. the usefulness of canon as an industrial process will be determined by the ability of the system to recover from major disturbances in feed composition. the canon process relies on the stable interaction between only two bacterial populations: nitrosomonas-like aerobic and planctomycete-like anaerobic ammonium oxidising bacteria. the ... | 2001 | 11876366 |
| immunological detection of nitrospira-like bacteria in various soils. | chemolithotrophic nitrite oxidizers were enriched from five different soils including freshwater marsh, permafrost, garden, agricultural, and desert soils and monitored during the cultivation procedure. immunoblot analysis was used to identify the nitrite oxidizing organisms with monoclonal antibodies, which recognize the key enzyme of nitrite oxidation in a genus-specific reaction [bartosch et al. (1999) appl environ microbiol 65:4126-4133]. the morphological characteristics of the enriched nit ... | 2002 | 11984626 |
| the microbial community composition of a nitrifying-denitrifying activated sludge from an industrial sewage treatment plant analyzed by the full-cycle rrna approach. | the composition of the microbial community present in the nitrifying-denitrifying activated sludge of an industrial wastewater treatment plant connected to a rendering facility was investigated by the full-cycle rrna approach. after dna extraction using three different methods, 94 almost full-length 16s rrna gene clones were retrieved and analyzed phylogenetically. 59% of the clones were affiliated with the proteobacteria and clustered with the beta- (29 clones), alpha- (24), and delta-class (2 ... | 2002 | 12086193 |
| diversity of 16s rdna and naphthalene dioxygenase genes from coal-tar-waste-contaminated aquifer waters. | microbial diversity in four wells along a groundwater flowpath in a coal-tar-waste-contaminated aquifer was examined using rflp analysis of both 16s rdna and naphthalene dioxygenase (ndo) genes. amplified ribosomal dna restriction analysis (ardra) relied upon eubacteria-specific primers to generate four clone libraries. from each library, 100 clones were randomly picked for analysis. sixty percent of 400 clones contained unique ardra patterns. diversity indices calculated for each community were ... | 2002 | 12087425 |
| in situ characterization of nitrifiers in an activated sludge plant: detection of nitrobacter spp. | the purpose of this work was to investigate microbial ecology of nitrifiers at the genus level in a typical full-scale activated sludge plant. | 2002 | 12174041 |
| the development and use of real-time pcr for the quantification of nitrifiers in activated sludge. | chemical analytical data has long been used to monitor the performance of activated sludge plants even though the process relies on the performance of microorganisms. it is now evident that a rapid and reliable quantitative method is required, to be able to monitor the organisms responsible for nutrient transformation and their activities, allowing avenues for more efficient nutrient removal. the development of real-time or quantitative polymerase chain reaction (pcr) also known as taqman or 5'- ... | 2002 | 12216635 |
| go or no go for gel entrapped nitrifiers? a belgian case study. | in the coming years, as stricter environmental requirements are imposed, many european union wastewater treatment plants (wwtp) need to be expanded and/or upgraded. this requires considerable investments. optimising the renovation recourses can lead to significant savings. the use of entrapped nitrifying bacteria for upgrading of wwtp towards nutrient removal may be benificial. long term pilot tests were performed to evaluate a so-called pellet reactor. differences in performance and microbiolog ... | 2002 | 12216669 |
| diversity of nitrifying bacteria in full-scale chloraminated distribution systems. | chloramination for secondary disinfection of drinking water often promotes the growth of nitrifying bacteria in the distribution system due to the ammonia introduced by chloramine formation and decay. this study involved the application of molecular biology techniques to explore the types of ammonia-oxidizing bacteria (aob) and nitrite-oxidizing bacteria (nob) present in several full-scale chloraminated systems. the results of aob community characterization indicated the ubiquitous detection of ... | 2003 | 12465801 |
| quantification of nitrosomonas oligotropha and nitrospira spp. using competitive polymerase chain reaction in bench-scale wastewater treatment reactors operating at different solids retention times. | the effect of solids retention time (srt) on ammonia-and nitrite-oxidizing bacteria was measured by nitrosomonas oligotropha-like ammonia monooxygenase a and nitrospira 16s rdna competitive polymerase chain reaction assays in a complete-mix, bench-scale, activated-sludge system. during steady-state operation, nitrification was complete in the 20- and 10-day srt reactors, nearly complete in the 5-day srt reactor, and incomplete in the 2-day srt reactor (76% ammonia oxidation and 85% nitrite oxida ... | 2002 | 12469950 |
| a culture-independent survey of the bacterial community in a radon hot spring. | paralana is an active, radon-containing hot spring situated in a region of south australia's flinders ranges with a long history of hydrothermal activity. our aim was to determine the bacterial composition of paralana using a culture-independent, 16s rrna-based technique. the presence of a diverse bacterial community was strongly suggested by the large number (approximately 180) of different ribotypes obtained upon analysis of nine hot spring samples. dna sequencing of paralana 16s rrna genes co ... | 2002 | 12530236 |
| real-time pcr quantification of nitrifying bacteria in a municipal wastewater treatment plant. | real-time pcr assays using taqman or molecular beacon probes were developed and optimized for the quantification of total bacteria, the nitrite-oxidizing bacteria nitrospira, and nitrosomonas oligotropha-like ammonia oxidizing bacteria (aob) in mixed liquor suspended solids (mlss) from a municipal wastewater treatment plant (wwtp) using a single-sludge nitrification process. the targets for the real-time pcr assays were the 16s rrna genes (16s rdna) for bacteria and nitrospira spp. and the amoa ... | 2003 | 12564907 |
| nitrifying microbial community analysis of nitrite accumulating biofilm reactor by fluorescence in situ hybridization. | biological nitrogen removal via nitrite pathway in wastewater treatment is very important especially in the cost of aeration and as an electron donor for denitrification. wastewater nitrification and nitrite accumulations were carried out in a biofllm reactor. the biofilm reactor showed almost complete nitrification and most of the oxidized ammonium was present as nitrite at the ammonium load of 1.2 kg n/m3/d. nitrite accumulation was achieved by the selective inhibition of nitrite oxidizers by ... | 2003 | 12578180 |
| activity and population structure of nitrifying bacteria in an activated-sludge reactor containing polymer beads. | photo-crosslinked polymer beads were introduced into a laboratory activated-sludge unit containing municipal sewage sludge and the effect on nitrifying capacity was examined. the ammonia load started at a nitrogen-loading rate of 0.02 kg m(-3) day(-1) and was increased stepwise. it was found that the bead-containing unit could almost completely oxidize ammonia (over 95%) up to a nitrogen-loading rate of 0.216 kg m(-3) day(-1), whereas the maximum loading rate of the control unit (without polymer ... | 2003 | 12662175 |
| microbial composition and structure of a rotating biological contactor biofilm treating ammonium-rich wastewater without organic carbon. | high nitrogen losses were observed in a rotating biological contactor (rbc) treating ammonium-rich (up to 500 mg nh4(+)-n/l) but organic-carbon-poor leachate from a hazardous waste landfill in kölliken, switzerland. the composition and spatial structure of the microbial community in the biofilm on the rbc was analyzed with specific attention for the presence of aerobic ammonium and nitrite oxidizing bacteria and anaerobic ammonium oxidizers. anaerobic ammonium oxidation (anammox) involves the ox ... | 2003 | 12704553 |
| structure and activity of multiple nitrifying bacterial populations co-existing in a biofilm. | a biofilm from a nitrifying pilot-scale sequencing batch reactor was investigated for effects of varying process conditions on its microscale activity and structure. microsensor measurements of oxygen, substrates and products of nitrification were applied under incubation at different ammonium and oxygen concentrations which reflected various situations during a treatment cycle. a high net n loss was observed under high ammonium (ha) concentrations in contrast to low ones. additionally, results ... | 2003 | 12713462 |
| nitrification efficiency and nitrifying bacteria abundance in combined as-rbc and a2o systems. | this study makes a comparison between the nitrification performance of tncu-i (a combined activated sludge-rotating biological contactor process) and a2o systems by the use of a pilot plant and batch experiments. the nitrifier abundance in both systems was determined, using cloning-denaturing gradient gel electrophoresis (dgge) and fluorescent in-situ hybridization (fish), to investigate the role of rotating biological contactor in the tncu-i process. the stability of the nitrification performan ... | 2003 | 12727236 |
| community analysis of ammonia and nitrite oxidizers during start-up of nitritation reactors. | partial nitrification of ammonium to nitrite under oxic conditions (nitritation) is a critical process for the effective use of alternative nitrogen removal technologies from wastewater. here we investigated the conditions which promote establishment of a suitable microbial community for performing nitritation when starting from regular sewage sludge. reactors were operated in duplicate under different conditions (ph, temperature, and dilution rate) and were fed with 50 mm ammonium either as syn ... | 2003 | 12788718 |
| in situ distribution and activity of nitrifying bacteria in freshwater sediment. | nitrification was investigated in a model freshwater sediment by the combined use of microsensors and fluorescence in situ hybridization with rrna-targeted oligonucleotide probes. in situ nitrification activity was restricted mainly to the upper 2 mm of the sediment and coincided with the maximum abundance of nitrifying bacteria, i.e. 1.5 x 107 cells cm-3 for ammonia-oxidizing beta-proteobacteria (aob) and 8.6 x 107 cells cm-3 for nitrospira-like nitrite-oxidizing bacteria (nob). cell numbers of ... | 2003 | 12919415 |
| microbial quantification in activated sludge: the hits and misses. | since the implementation of the activated sludge process for treating wastewater, there has been a reliance on chemical and physical parameters to monitor the system. however, in biological nutrient removal (bnr) processes, the microorganisms responsible for some of the transformations should be used to monitor the processes with the overall goal to achieve better treatment performance. the development of in situ identification and rapid quantification techniques for key microorganisms involved ... | 2003 | 14518863 |
| power analysis for real-time pcr quantification of genes in activated sludge and analysis of the variability introduced by dna extraction. | the aims of this study were to determine the power of discrimination of the real-time pcr assay for monitoring fluctuations in microbial populations within activated sludge and to identify sample processing points where methodological changes are needed to minimize the variability in target quantification. dna was extracted using a commercially available kit from mixed liquor samples taken from the aeration tank of four bench-scale activated-sludge reactors operating at 2-, 5-, 10-, and 20-day s ... | 2003 | 14602618 |
| long-term succession of structure and diversity of a biofilm formed in a model drinking water distribution system. | in this study, we examined the long-term development of the overall structural morphology and community composition of a biofilm formed in a model drinking water distribution system with biofilms from 1 day to 3 years old. visualization and subsequent quantification showed how the biofilm developed from an initial attachment of single cells through the formation of independent microcolonies reaching 30 micro m in thickness to a final looser structure with an average thickness of 14.1 micro m and ... | 2003 | 14602654 |
| molecular assessment of ammonia- and nitrite-oxidizing bacteria in full-scale activated sludge wastewater treatment plants. | nitrification was assessed in two full-scale wastewater treatment plants (wwtps) over time using molecular methods. both wwtps employed a complete-mix suspended growth, aerobic activated sludge process (with biomass recycle) for combined carbon and nitrogen treatment. however, one facility treated primarily municipal wastewater while the other only industrial wastewater. real time pcr assays were developed to determine copy numbers for total 16s rdna (a measure of biomass content), the amoa gene ... | 2003 | 14682578 |
| analysis and comparison of the microbial community structures of two enrichment cultures capable of reductively dechlorinating tce and cis-dce. | in order to study the effect of different chloroethenes (electron acceptors) on the bacterial composition of dechlorinating communities, two reductive dechlorinating enrichment cultures were developed that were able to reduce trichloroethene (tce) and cis-1,2-dichloroethene (cis-dce) to ethene using hydrogen as electron donor, respectively. the inoculum for the cultures was material from a methanogenic fluidized bed reactor (fbr), which was originally seeded with digester sludge and showed a sta ... | 2004 | 14686940 |
| fluorescence in situ hybridization analysis of nitrifiers in piggery wastewater treatment reactors. | fluorescence in situ hybridization (fish) was performed to analyze the nitrifying microbial communities in an activated sludge reactor (asr) and a fixed biofilm reactor (fbr) for piggery wastewater treatment. heterotrophic oxidation and nitrification were occurring simultaneously in the asr and the cod and nitrification efficiencies depend on the loads. in the fbr nitrification efficiency also depends on ammonium load to the reactor and nitrite was accumulated when free ammonia concentration was ... | 2004 | 15137442 |
| molecular analysis of the community structure of nitrifying bacteria in a continuous-flow bioreactor. | we herein report the diversity and relative abundance of chemolithotrophic nitrifying bacteria in a continuous-flow bioreactor using 16s-ribosomal rna quantitative dot-blot hybridizations. about 14.9% of the total bacterial population, determined by epifluorescence microscopy in the bioreactor suspended phase, was represented by nitrifying bacteria. of this fraction, ammonia- and nitrite-oxidizing bacteria accounted for 10% and 90%, respectively, the latter group being mostly nitrospira-like. on ... | 2004 | 15176741 |
| high nitrification rate at low ph in a fluidized bed reactor with chalk as the biofilm carrier. | a typical steady state bulk ph of about 5 was established in a nitrifying fluidized bed with chalk as the only buffer agent. in spite of the low ph, high rate nitrification was observed with the nitrification kinetic parameters in the chalk reactor similar to those of biological reactors operating at ph>7. various methods were used to determine the reasons for high rate nitrification at such low ph including (i) determination of bacterial species, (ii) microsensor measurements in the biofilm, an ... | 2004 | 15303729 |
| effect of solid hold-up on nitrite accumulation in a biofilm reactor--molecular characterization of nitrifying communities. | biological ammonium oxidation was carried out in two inverse turbulent bed reactors fed with synthetic mineral wastewater containing a high ammonium concentration (100 mg n-nh4+/l). both reactors were started-up and operated in the same conditions except for the solid carrier concentration: the solid hold-up ratios applied, defined as the ratios of static to expanded bed height, were 0.1 and 0.3 in reactors r10 and r30 respectively. these two solid hold-up ratios generate different particle-to-p ... | 2004 | 15303732 |
| a survey of the composition and diversity of bacterial populations in bleached kraft pulp-mill wastewater secondary treatment systems. | bacterial community compositions from 10 pulp- and paper-mill treatment systems were compared using both traditional and molecular techniques. 16s-rflp (random fragment length polymorphisms) analysis was used to examine the genotypic profiles of the whole bacterial community of each treatment system. although all the communities shared approximately 60% of their dna band pattern, as determined by computer-assisted cluster analysis, each community displayed a unique profile that was stable over t ... | 2004 | 15467789 |
| microbial community structure in a thermophilic anaerobic hybrid reactor degrading terephthalate. | a thermophilic terephthalate-degrading methanogenic consortium was successfully enriched for 272 days in an anaerobic hybrid reactor, and the microbial structure was characterized using terminal rflps, clone libraries and fluorescence in-situ hybridization with rrna-targeted oligonucleotide probes. all the results suggested that methanothrix thermophila-related methanogens, desulfotomaculum-related bacterial populations in the gram-positive low-g + c group, and op5-related populations were the k ... | 2004 | 15470120 |
| in-situ characterization of microbial community in an a/o submerged membrane bioreactor with nitrogen removal. | the bacterial community involved in removing nitrogen from sewage and their preferred do environment within an anoxic/oxic membrane bioreactor (a/o mbr) was investigated. a continuously operated laboratory-scale a/o mbr was maintained for 360 d. at a sludge age of 150 d and a c/n ratio of 3.5, the system was capable of removing 88% of the influent nitrogen from raw wastewater through typical nitrogen removal transformations (i.e. aerobic ammonia oxidation and anoxic nitrate reduction). character ... | 2004 | 15566185 |
| succession of bacterial community structure and diversity in a paddy soil oxygen gradient. | cultivation-independent techniques were applied to assess the succession and phylogenetic composition of bacterial communities in a vertical oxygen gradient in flooded, unplanted paddy soil microcosms. microsensor measurements showed that within 6 h of flooding, oxygen was depleted from 200 microm at the floodwater-soil interface to undetectable amounts at a depth of approximately 2 mm and below. the gradient was quite stable over time, although the oxygen depletion was less pronounced 84 days t ... | 2005 | 15683399 |
| bacterial community shift along a subsurface geothermal water stream in a japanese gold mine. | change of bacterial community occurring along a hot water stream in the hishikari gold mine, japan, was investigated by applying a combination of various culture-independent techniques. the stream, which is derived from a subsurface anaerobic aquifer containing plentiful co2, ch4, h2, and nh4+, emerges in a mine tunnel 320 m below the surface providing nutrients for a lush microbial community that extends to a distance of approximately 7 m in the absence of sunlight-irradiation. over this distan ... | 2005 | 15776216 |
| combined approach for characterization of uncultivated magnetotactic bacteria from various aquatic environments. | both magnetic collection and "race track" purification techniques were highly effective for selective enrichment of magnetotactic bacteria (mtb) from complex communities, as suggested by amplified ribosomal dna restriction analysis and denaturing gradient gel electrophoresis combined with sequence analysis of 16s rrna genes. using these purification methods, the occurrence and diversity of mtb in microcosms from various marine and freshwater environments were assayed by using a combined microsco ... | 2005 | 15870364 |
| comparative analysis of nitrifying bacteria in full-scale oxidation ditch and aerated nitrification biofilter by using fluorescent in situ hybridization (fish) and denaturing gradient gel electrophoresis (dgge). | in this study, nitrification performances and composition of nitrifying populations in a full-scale oxidation ditch and a high-rate submerged media nitrification biofilter were comparatively analyzed. in addition to different reactor configurations, effects of differing operational conditions on the nitrification efficiency and bacterial diversity were also explored and evaluated thoroughly. in microbial analysis of sludge samples fluorescent in situ hybridization (fish) and denaturing gradient ... | 2005 | 15887565 |
| effect of temperature and free ammonia on nitrification and nitrite accumulation in landfill leachate and analysis of its nitrifying bacterial community by fish. | the cause of seasonal failure of a nitrifying municipal landfill leachate treatment plant utilizing a fixed biofilm was investigated by wastewater analyses and batch respirometric tests at every treatment stage. nitrification of the leachate treatment plant was severely affected by the seasonal temperature variation. high free ammonia (nh3-n) inhibited not only nitrite oxidizing bacteria (nob) but also ammonia oxidizing bacteria (aob). in addition, high ph also increased free ammonia concentrati ... | 2006 | 15927463 |
| comparison of nitrification performance and microbial community between submerged membrane bioreactor and conventional activated sludge system. | a submerged membrane bioreactor (smbr) and a conventional activated sludge system (cas) were compared in parallel over a period of more than 260 days on treating synthetic ammonia-bearing inorganic wastewater without sludge purge under decreased hydraulic retention times (hrts). conversion of nh4(+)-n to no3(-)-n was achieved with an efficiency of over 98% at an hrt > or = 10 h in the smbr, while similar performance was obtained at an hrt > or = 20 h in the cas. denaturing gradient gel electroph ... | 2005 | 16003978 |
| dna microarray detection of nitrifying bacterial 16s rrna in wastewater treatment plant samples. | a small scale dna microarray containing a set of oligonucleotide probes targeting the 16s rrnas of several groups of nitrifying bacteria was developed for the monitoring of wastewater treatment plant samples. the microarray was tested using reference rrnas from pure cultures of nitrifying bacteria. characterization of samples collected from an industrial wastewater treatment facility demonstrated that nitrifying bacteria could be detected directly by microarray hybridization without the need for ... | 2005 | 16009395 |
| in situ substrate conversion and assimilation by nitrifying bacteria in a model biofilm. | local nitrification and carbon assimilation activities were studied in situ in a model biofilm to investigate carbon yields and contribution of distinct populations to these activities. immobilized microcolonies (related to nitrosomonas europaea/eutropha, nitrosomonas oligotropha, nitrospira sp., and to other bacteria) were incubated with [14c]-bicarbonate under different experimental conditions. nitrifying activity was measured concomitantly with microsensors (oxygen, ammonium, nitrite, nitrate ... | 2005 | 16104862 |
| perchlorate and nitrate remediation efficiency and microbial diversity in a containerized wetland bioreactor. | we have developed a method to remove perchlorate (14-27 microg/l) and nitrate (48 mg/l) from contaminated groundwater using a wetland bioreactor. the bioreactor has operated continuously in a remote field location for more than 2 yr with a stable ecosystem of indigenous organisms. this study assesses the bioreactorfor long-term perchlorate and nitrate remediation by evaluating influent and effluent groundwater for oxidation-reduction conditions and nitrate and perchlorate concentrations. total c ... | 2005 | 16128443 |
| the microbial community in a 2,4-dinitrophenol-digesting reactor as revealed by 16s rdna gene analysis. | the microbial community of a 2,4-dinitrophenol-digesting reactor was investigated using different molecular biological techniques based on 16s rdna gene sequences. a pcr-denaturing gradient gel electrophoresis (dgge) analysis of the bacterial community in the reactor showed that one strong and five minor bands were observed in the dgge profile. the results of excising and sequencing dgge bands suggested that members of rhodococcus, nocardioides, and nitrospira species were present in the reactor ... | 2003 | 16233485 |
| nitrobacter and nitrospira genera as representatives of nitrite-oxidizing bacteria: detection, quantification and growth along the lower seine river (france). | pollution from agriculture and urban effluents influences the ecology and biochemical functioning of the seine river. nitrification dominates nitrogen transformations downstream of the effluents of the paris wastewater treatment plant (wwtp) at achères, treating, by activated sludge the wastewater of 6.5 million inhabitant equivalents from paris and its suburbs, without nitrification and denitrification treatment. it discharges effluents containing large amounts of nitrogen, ammonium mostly (app ... | 2005 | 16303163 |
| nitrification performance and microbial community dynamics in a submerged membrane bioreactor with complete sludge retention. | a submerged membrane bioreactor (mbr) supplied with inorganic ammonium-bearing wastewater (nh(4)(+)-n, 500 mgl(-1)) was operated for 260 days without sludge purge under decreased hydraulic retention times (hrt) through six steps (from 30 to 5h). almost complete nitrification was obtained at a volumetric loading rate (vlr)1.2g nh(4)(+)-nl(-1)day(-1). the sludge nitrification activities were evaluated at each stage. the specific ammonium oxidizing rate (saor) decreased from the initial 0.45 to 0.1 ... | 2006 | 16310272 |
| moderately thermophilic nitrifying bacteria from a hot spring of the baikal rift zone. | samples from three hot springs (alla, seya and garga) located in the northeastern part of baikal rift zone (buryat republic, russia) were screened for the presence of thermophilic nitrifying bacteria. enrichment cultures were obtained solely from the garga spring characterized by slightly alkaline water (ph 7.9) and an outlet temperature of 75 degrees c. the enrichment cultures of the ammonia- and nitrite oxidizers grew at temperature ranges of 27-55 and 40-60 degrees c, respectively. the temper ... | 2005 | 16332328 |
| high levels of nitrifying bacteria in intermittently aerated reactors treating high ammonia wastewater. | changes in the fractions of ammonia-oxidizing bacteria and nitrite-oxidizing bacteria in two laboratory-scale reactors were investigated using 16s rrna probe hybridizations. the reactors were operated in intermittent aeration mode and different aeration cycles to treat anaerobically digested swine wastewater with ammonia concentrations up to 175 mg nh(3)-n/l. high ammonia removals (>98.8%) were achieved even with increased nitrogen loads and lower aeration: non-aeration time ratios of 1h:3h. nit ... | 2005 | 16332337 |
| influence of inorganic nitrogen management regime on the diversity of nitrite-oxidizing bacteria in agricultural grassland soils. | to assess links between the diversity of nitrite-oxidizing bacteria (nob) in agricultural grassland soils and inorganic n fertilizer management, nob communities in fertilized and unfertilized soils were characterized by analysis of clone libraries and denaturing gradient gel electrophoresis (dgge) of 16s rrna gene fragments. previously uncharacterized nitrospira-like sequences were isolated from both long-term-fertilized and unfertilized soils, but dgge migration patterns indicated the presence ... | 2005 | 16332819 |
| effects of aeration cycles on nitrifying bacterial populations and nitrogen removal in intermittently aerated reactors. | the effects of the lengths of aeration and nonaeration periods on nitrogen removal and the nitrifying bacterial community structure were assessed in intermittently aerated (ia) reactors treating digested swine wastewater. five ia reactors were operated in parallel with different aeration-to-nonaeration time ratios (ana). populations of ammonia-oxidizing bacteria (aob) and nitrite-oxidizing bacteria (nob) were monitored using 16s rrna slot blot hybridizations. aob species diversity was assessed u ... | 2005 | 16332848 |
| identification of bacteria in biofilm and bulk water samples from a nonchlorinated model drinking water distribution system: detection of a large nitrite-oxidizing population associated with nitrospira spp. | in a model drinking water distribution system characterized by a low assimilable organic carbon content (<10 microg/liter) and no disinfection, the bacterial community was identified by a phylogenetic analysis of rrna genes amplified from directly extracted dna and colonies formed on r2a plates. biofilms of defined periods of age (14 days to 3 years) and bulk water samples were investigated. culturable bacteria were associated with proteobacteria and bacteriodetes, whereas independently of culti ... | 2005 | 16332854 |
| bacterial community succession in natural river biofilm assemblages. | temporal bacterial community changes in river biofilms were studied using 16s rrna gene-based polymerase chain reaction-denaturing gradient gel electrophoresis (dgge) followed by sequence analysis. naturally occurring biofilms were sampled in 2001 during an undisturbed 7-month low-water period in the river garonne (sw france). during the sampling period epilithic biomass exhibited a particular pattern: two 3-month periods of accumulation that resulted in two peaks in summer and fall, each at abo ... | 2005 | 16341639 |
| nitrospira-like bacteria associated with nitrite oxidation in freshwater aquaria. | oxidation of nitrite to nitrate in aquaria is typically attributed to bacteria belonging to the genus nitrobacter which are members of the alpha subdivision of the class proteobacteria. in order to identify bacteria responsible for nitrite oxidation in aquaria, clone libraries of rrna genes were developed from biofilms of several freshwater aquaria. analysis of the rdna libraries, along with results from denaturing gradient gel electrophoresis (dgge) on frequently sampled biofilms, indicated the ... | 1998 | 16349486 |
| analysis of community composition of biofilms in a submerged filter system for the removal of ammonia and phenol from industrial wastewater. | the bacterial diversity of a submerged filter, used for the removal of ammonia and phenol from an industrial wastewater with high salinity, was studied by a cultivation-independent approach based on pcr/tgge (temperature-gradient gel electrophoresis). the wastewater treatment plant (laboratory scale) combined the nitrification and denitrification processes and consisted of two separated columns (one anoxic and one aerated) connected through a valve. the spatial diversity of bacterial communities ... | 2006 | 16417512 |
| volatile fatty acid impacts on nitrite oxidation and carbon dioxide fixation in activated sludge. | batch test were performed to assess nitrite removal, nitrate formation, co2 fixation, gaseous nitrogen production and microbial density in activated sludge exposed to volatile fatty acid (vfa) mixtures. nitrite removal and nitrate formation were both affected by the presence of vfas, but to different degrees. nitrate formation rates were reduced to a greater extent (79%) than nitrite removal rates (36%) resulting in an apparent unbalanced nitrite oxidation reaction. since the total bacterial den ... | 2006 | 16436292 |
| effect of nitrite concentration on the distribution and competition of nitrite-oxidizing bacteria in nitratation reactor systems and their kinetic characteristics. | genus nitrospira and nitrobacter species are the key nitrite-oxidizing bacteria (nob) in nitrifying wastewater treatment plants. it has been hypothesized that genus nitrospira are k-strategists and can exploit low amounts of nitrite more efficiently than nitrobacter. in contrast, nitrobacter species are r-strategists that can grow faster than nitrospira. to elucidate the k/r hypothesis and to analyze the effect of substrate (nitrite) concentration on the competition and distribution of the two n ... | 2006 | 16460781 |
| selective enrichment and molecular characterization of a previously uncultured nitrospira-like bacterium from activated sludge. | previously uncultured nitrite-oxidizing bacteria affiliated to the genus nitrospira have for the first time been successfully enriched from activated sludge from a municipal wastewater treatment plant. during the enrichment procedure, the abundance of the nitrospira-like bacteria increased to approximately 86% of the total bacterial population. this high degree of purification was achieved by a novel enrichment protocol, which exploits physiological features of nitrospira-like bacteria and inclu ... | 2006 | 16478447 |
| molecular analysis of the bacterial community in a continental high-temperature and water-flooded petroleum reservoir. | water from a continental high-temperature, long-term water-flooded petroleum reservoir in huabei oilfield in china was analysed for its bacterial community and diversity. the bacteria were characterized by their 16s rrna genes. a 16s rrna gene clone library was constructed from the community dna, and using restriction fragment length polymorphism analysis, 337 randomly selected clones were clustered with 74 operational taxonomic units. sequencing and phylogenetic analyses showed that the screene ... | 2006 | 16553837 |
| community structure, abundance, and in situ activity of nitrifying bacteria in river sediments as determined by the combined use of molecular techniques and microelectrodes. | the community structure, spatial distributions, and in situ activity of ammonia-oxidizing bacteria (aob) representing the betaproteobacteria and nitrite-oxidizing bacteria (nob) representing the genus nitrospira in three different river sediments with different pollution sources and levels along the niida river, hachinohe, japan, were investigated by the combined use of 16s rrna gene-cloning analysis, real-time quantitative polymerase chain reaction (rtq-pcr) assays, and microelectrodes. the goa ... | 2006 | 16568767 |
| changes in the community structure and activity of betaproteobacterial ammonia-oxidizing sediment bacteria along a freshwater-marine gradient. | to determine whether the distribution of estuarine ammonia-oxidizing bacteria (aob) was influenced by salinity, the community structure of betaproteobacterial ammonia oxidizers (aob) was characterized along a salinity gradient in sediments of the ythan estuary, on the east coast of scotland, uk, by denaturant gradient gel electrophoresis (dgge), cloning and sequencing of 16s rrna gene fragments. ammonia-oxidizing bacteria communities at sampling sites with strongest marine influence were dominat ... | 2006 | 16584480 |
| population dynamics and in situ kinetics of nitrifying bacteria in autotrophic nitrifying biofilms as determined by real-time quantitative pcr. | population dynamics of ammonia-oxidizing bacteria (aob) and uncultured nitrospira-like nitrite-oxidizing bacteria (nob) dominated in autotrophic nitrifying biofilms were determined by using real-time quantitative polymerase chain reaction (rtq-pcr) and fluorescence in situ hybridization (fish). although two quantitative techniques gave the comparable results, the rtq-pcr assay was easier and faster than the fish technique for quantification of both nitrifying bacteria in dense microcolony-formin ... | 2006 | 16596626 |
| acidophilic microbial communities catalyzing sludge bioleaching monitored by fluorescent in situ hybridization. | biological autotrophic sulfur oxidation processes have been proposed to remove heavy metals from wastewater treatment sludge by bioleaching. we made a characterization of the microbial population in batch and continuous sludge bioleaching reactors using fluorescent in situ hybridization of fluorescently-labeled oligonucleotidic probes targeting rrna in a 'top to bottom approach'. batch incubations of sludge with 0.2% (w/v) elemental sulfur resulted in a ph value of 5. alpha-proteobacteria hybrid ... | 2006 | 16622787 |
| competition between nitrospira spp. and nitrobacter spp. in nitrite-oxidizing bioreactors. | in this work the question was addressed if in nitrite-oxidizing activated sludge systems the environmental competition between nitrobacter spp. and nitrospira spp., which only recently has been discovered to play a role in these systems, is affected by the nitrite concentrations. two parallel chemostats were inoculated with nitrifying-activated sludge containing nitrospira and operated under identical conditions. after addition of nitrobacter to both chemostats, the nitrite concentration in the ... | 2006 | 16703620 |
| nitrification in a biofilm at low ph values: role of in situ microenvironments and acid tolerance. | the sensitivity of nitrifying bacteria to acidic conditions is a well-known phenomenon and generally attributed to the lack and/or toxicity of substrates (nh3 and hno2) with decreasing phs. in contrast, we observed strong nitrification at a ph around 4 in biofilms grown on chalk particles and investigated the following hypotheses: the presence of less acidic microenvironments and/or the existence of acid-tolerant nitrifiers. microelectrode measurements (in situ and under various experimental con ... | 2006 | 16751543 |
| phenotypic properties and microbial diversity of methanogenic granules from a full-scale upflow anaerobic sludge bed reactor treating brewery wastewater. | methanogenic granules from an anaerobic bioreactor that treated wastewater of a beer brewery consisted of different morphological types of granules. in this study, the microbial compositions of the different granules were analyzed by molecular microbiological techniques: cloning, denaturing gradient gel electrophoresis and fluorescent in situ hybridization (fish), and scanning and transmission electron microscopy. we propose here that the different types of granules reflect the different stages ... | 2006 | 16820491 |
| nitrite concentration influences the population structure of nitrospira-like bacteria. | chemolithoautotrophic nitrite oxidizers of the genus nitrospira are a monophyletic but diverse group of organisms, are widely distributed in many natural habitats, and play a key role in nitrogen elimination during biological wastewater treatment. phylogenetic analyses of cloned 16s rrna genes and fluorescence in situ hybridization with newly developed rrna-targeted oligonucleotide probes revealed coexistence of uncultured members of sublineages i and ii of the genus nitrospira in biofilm and ac ... | 2006 | 16872410 |
| ecophysiology and niche differentiation of nitrospira-like bacteria, the key nitrite oxidizers in wastewater treatment plants. | nitrite-oxidizing bacteria of the genus nitrospira are key nitrifiers in wastewater treatment plants. pure cultures of these organisms are unavailable, but cultivation-independent molecular methods make it possible to detect nitrospira-like bacteria in environmental samples and to investigate their ecophysiology. comprehensive screening of natural and engineered habitats and of public databases for 16s rrna sequences of nitrospira-like bacteria revealed a surprisingly high biodiversity in the ge ... | 2006 | 16898133 |
| impact of prehybridization pcr amplification on microarray detection of nitrifying bacteria in wastewater treatment plant samples. | a gel-based microarray that included a set of 26 oligonucleotide probes targeting all nitrifying bacteria at varying levels of specificity suggested the presence of targeted microorganisms when hybridized to rna isolated from a wastewater treatment plant, but could not discriminate between perfectly matched and mismatched sequences due in part to low signal intensity. to enhance sensitivity and improve discrimination, polymerase chain reaction was used to selectively amplify the 16s rrna genes o ... | 2006 | 16913917 |
| vertical distribution of nitrifying populations in bacterial biofilms from a full-scale nitrifying trickling filter. | cryosectioned biofilm from three depths (0.5, 3.0 and 6.0 m) in a full-scale nitrifying trickling filter (ntf) were studied using fluorescence in situ hybridization (fish). a large number of sections were used to determine how the biofilm thickness, structure and community composition varied with depth along the ammonium concentration gradient in the ntf, and how the ammonia-oxidizing bacteria (aob) and nitrite-oxidizing bacteria (nob) were distributed vertically within the biofilm. both the bio ... | 2006 | 17014502 |
| effect of the concentration of suspended solids on the enzymatic activities and biodiversity of a submerged membrane bioreactor for aerobic treatment of domestic wastewater. | a pilot-scale submerged membrane bioreactor was used for the treatment of domestic wastewater in order to study the influence of the variations in the concentration of volatile suspended solids (vss) on the enzymatic activities (acid and alkaline phosphatases, glucosidase, protease, esterase, and dehydrogenase) and biodiversity of the bacterial community in the sludge. the influence of vss concentration was evaluated in two separated experiments, which were carried out in two different seasons o ... | 2007 | 17043829 |
| cultivation-dependent and cultivation-independent characterization of the microbial community in acid mine drainage associated with acidic pb/zn mine tailings at lechang, guangdong, china. | cultivation-based and molecular approaches were used to characterize the phylogenetic composition and structure of the microbial community in an extremely acidic (ph 2.0) acid mine drainage (amd) associated with pb/zn mine tailings that were undergoing vigorous acid generation. acidophilic bacteria were isolated and enumerated on solid media, and were found to be restricted to isolates related to acidithiobacillus ferrooxidans and acidiphilium cryptum. by contrast, cloning and phylogenetic analy ... | 2007 | 17059483 |
| communities of archaea and bacteria in a subsurface radioactive thermal spring in the austrian central alps, and evidence of ammonia-oxidizing crenarchaeota. | scanning electron microscopy revealed great morphological diversity in biofilms from several largely unexplored subterranean thermal alpine springs, which contain radium 226 and radon 222. a culture-independent molecular analysis of microbial communities on rocks and in the water of one spring, the "franz-josef-quelle" in bad gastein, austria, was performed. four hundred fifteen clones were analyzed. one hundred thirty-two sequences were affiliated with 14 bacterial operational taxonomic units ( ... | 2007 | 17085711 |
| nitrifying bacterial communities in an aquaculture wastewater treatment system using fluorescence in situ hybridization (fish), 16s rrna gene cloning, and phylogenetic analysis. | aquaculture, especially shrimp farming, has played a major role in the growth of thailand's economy in recent years, as well as in many south east asian countries. however, the nutrient discharges from these activities have caused adverse impacts on the quality of the receiving waterways. in particular nitrogenous compounds, which may accumulate in aquaculture ponds, can be toxic to aquatic animals and cause environmental problems such as eutrophication. the mineralization process is well known, ... | 2007 | 17115448 |
| molecular diversity of microbial community in acid mine drainages of yunfu sulfide mine. | two acid mine drainage (amd) samples were studied by a pcr-based cloning approach, which were from yunfu sulfide mine in guangdong province, china. a total of 15 operational taxonomic units (otus) were obtained from the two amd samples. the percentage of overlapped otus in two amd samples was 42.1%. phylogenetic analysis revealed that the bacterium in the two samples fell into four putative divisions, which were nitrospira, alpha-proteobacteria, beta-proteobacteria, and gamma-proteobacteria four ... | 2007 | 17177020 |
| influences of infaunal burrows on the community structure and activity of ammonia-oxidizing bacteria in intertidal sediments. | influences of infaunal burrows constructed by the polychaete (tylorrhynchus heterochaetus) on o(2) concentrations and community structures and abundances of ammonia-oxidizing bacteria (aob) and nitrite-oxidizing bacteria (nob) in intertidal sediments were analyzed by the combined use of a 16s rrna gene-based molecular approach and microelectrodes. the microelectrode measurements performed in an experimental system developed in an aquarium showed direct evidence of o(2) transport down to a depth ... | 2007 | 17189445 |
| effect of free ammonia on the respiration and growth processes of an enriched nitrobacter culture. | the inhibitory effect of free ammonia (fa;nh(3)) on the metabolism of nitrobacter is investigated using a method that allows decoupling energy generation from growth processes. a lab-scale sequencing batch reactor (sbr) was operated for the enrichment of nitrobacter. fluorescent in situ hybridization (fish) analysis showed that 73% of the bacterial population in the reactor was nitrobacter, while no nitrospira was detected. batch tests were carried out to measure the oxygen uptake rate (our) by ... | 2007 | 17224173 |
| identification of acetate-utilizing bacteria and archaea in methanogenic profundal sediments of lake kinneret (israel) by stable isotope probing of rrna. | acetate is an important intermediate in the decomposition of organic matter in anoxic freshwater sediments. here, we identified distinct microorganisms active in its oxidation and transformation to methane in the anoxic methanogenic layers of lake kinneret (israel) profundal sediment by rrna-based stable isotope probing (rna-sip). after 18 days of incubation with amended [u-(13)c]acetate we found that archaeal 16s rrna was (13)c-labelled to a far greater extent than bacterial rrna. we identified ... | 2007 | 17227427 |
| diversity study of nitrifying bacteria in full-scale municipal wastewater treatment plants. | we hypothesize that activated-sludge processes having stable and complete nitrification have significant and similar diversity and functional redundancy among its ammonia- and nitrite-oxidizing bacteria, despite differences in temperature, solids retention time (srt), and other operating conditions. to evaluate this hypothesis, we examined the diversity of nitrifying bacterial communities in all seven water-reclamation plants (wrps) operated by metropolitan water reclamation district of greater ... | 2007 | 17254627 |
| investigation of total bacterial and ammonia-oxidizing bacterial community composition in a full-scale aerated submerged biofilm reactor for drinking water pretreatment in china. | the community composition of total bacteria and ammonia-oxidizing bacteria in a full-scale aerated submerged biofilm reactor for drinking water pretreatment was characterized by analysis of 16s rrna gene and the functional gene amoa, respectively. sampling was performed in february and in july. 16s rrna gene clone libraries revealed 13 bacterial divisions. at both sampling dates, the majority of clone sequences were related to the alpha- and betaproteobacteria. a minor proportion belonged to the ... | 2007 | 17263855 |
| concurrent nitrite oxidation and aerobic denitrification in activated sludge exposed to volatile fatty acids. | the goal of this research was to investigate the simultaneous occurrence of nitrification and denitrification by activated sludge exposed to volatile fatty acids (vfas) during aerobic wastewater treatment using a single-stage reactor. a mixture of vfas was spiked directly into a continuous-stirred tank reactor (cstr) to assess subsequent impacts on nitrite removal, nitrate formation, co(2) fixation, total bacterial density, and dominant nitrite oxidizing bacteria (nob) concentration (i.e., nitro ... | 2007 | 17304559 |
| [biodiversity of acidophiles in the sediment at an acid mine drainage site]. | a sediment sample was collected at an acid mine drainage site in anhui. the acidophiles composition and community structure in the sediment was studied with 16s rdna clone library and denaturing gradient gel electrophoresis (dgge). the results indicated that the acidophiles in the sediment were novel compared with the data in genbank. the acidophiles affiliated with acidobacteria, beta/gamma-proteobacteria, delta-proteobacteria, nitrospira, candidate division tm7, low g + c gram-positive. delta- ... | 2006 | 17326436 |
| high-density universal 16s rrna microarray analysis reveals broader diversity than typical clone library when sampling the environment. | molecular approaches aimed at detection of a broad-range of prokaryotes in the environment routinely rely on classifying heterogeneous 16s rrna genes amplified by polymerase chain reaction (pcr) using primers with broad specificity. the general method of sampling and categorizing dna has been to clone then sequence the pcr products. however, the number of clones required to adequately catalog the majority of taxa in a sample is unwieldy. alternatively, hybridizing target sequences to a universal ... | 2007 | 17334858 |