SEARCH · PubMed Health

Results for “NITROSOMONAS”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 361 records · Page 20Linked to original sources

PubMed2004

Effects of hydroxylamine on microbial community structure and function of autotrophic nitrifying biofilms determined by in situ hybridization and the use of microelectrodes.

Effects of hydroxylamine (NH2OH), an intermediate of NH4+ oxidation, on microbial community structure and function of two autotrophic nitrifying biofilms fed with and without NH2OH were analyzed by a 16S rRNA approach and the use of microelectrodes. In the NH2OH-added biofilm, partial oxidation of NH4+ to NO2- was observed, whereas complete oxidation of NH4+ to NO3- was achieved in the control biofilm. In situ hybridization results revealed that no nitrite-oxidizing bacteria (NOB) hybridized with any specific probes were detected in the NH2OH-added biofilm. Thus, the addition of low concentrations of NH2OH (250 microM) completely inhibited the growth of NOB. Phylogenetic analysis of 16S rDNA indicated that the ammonia-oxidizing bacteria (AOB) detected in both biofilms were closely related to Nitrosomonas europaea, and that the clone sequences from both biofilm libraries have more than 99% similarity to each other. However, in situ hybridization results revealed that the addition of NH2OH changed the form of growth pattern of the dominant Nitrosomonas spp. from dense clusters mode to single scattered cells mode. Microelectrode measurements revealed that the average NH4+ consumption rate calculated in the NH2OH-added biofilm was two times higher than that in the control biofilm. This clearly demonstrated that the oxidation of NH4+ was stimulated by NH2OH addition.

Biofilms↗

PubMed2004

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, and (iii) comparison of nitrification performance at low pH with a non-chalk fluidized bed reactor. Fluorescence in situ hybridization (FISH) using existing 16S rRNA-targeted oligonucleotide probes showed common nitrifying bacteria in the low pH chalk reactor. The prevalent nitrifying bacteria were identified in the Nitrosomonas oligotropha, Nitrosomonas europeae/eutropha, Nitrosospira and Nitrospira related groups, all well known nitrifiers. Microelectrode measurements showed that the pH in the biofilm was low and similar to that of the bulk pH. Finally, reactor performance using a non-chalk biofilm carrier (sintered glass) with the same bacterial inoculum also showed high rate nitrification below pH 5. The results suggest that inhibition of nitrification at low pH is highly overestimated.

Biofilms↗

PubMed2004

Community analysis of ammonia oxidizer in the oxygen-limited nitritation stage of OLAND system by DGGE of PCR amplified 16S rDNA fragments and FISH.

OLAND (oxygen limited autotrophic nitrification and denitrification) nitrogen removal system was constructed by coupling with oxygen limited nitritation stage and anaerobic ammonium oxidation stage. Ammonia oxidizer, as a kind of key bacteria in N cycle, plays an important role at the oxygen limited nitritation stage of OLAND nitrogen removal system. In this study, specific amplification of 16S rDNA fragment of ammonia oxidizer by nested PCR, separation of mixed PCR samples by denaturing gradient gel electrophoresis (DGGE), and the quantification of ammonia oxidizer by fluorescence in situ hybridization (FISH) were combined to investigate the shifts of community composition and quantity of ammonia oxidizer of the oxygen limited nitritation stage in OLAND system. It showed that the community composition of ammonia oxidizer changed drastically when dissolved oxygen was decreased gradually, and the dominant ammonia oxidizer of the steady nitrite accumulation stage were completely different from that of the early stage of oxygen limited nitritation identified by DGGE. It was concluded that the Nitrosomonas may be the dominant genus of ammonia oxidizer at the oxygen limited nitritation stage of OLAND system characterized by nested PCR-DGGE and FISH, and the percentage of Nitrosomonas was 72.5% +/- 0.8% of ammonia oxidizer at the steady nitrite accumulation stage detected by FISH.

Ammonia↗

PubMedDate not supplied

[Thermophilic nitrifying bacteria from hot springs].

A culture of thermophilic nitrifying bacteria was isolated from geothermal springs of Kamchatka (50-86 degrees C, pH 6.3-7.5) AND Tajig SSR (50-85 degrees C, pH 7.3-8.5). The culture oxidizes ammonium nitrogen at 40-70 degrees C. It resembles Nitrosomonas europea Winogradskyi by its morphology. Dimensions of the cells vary within 0.7-0.9 X 0.8-1.4 mcm. Each cell has a polar flagellum whose diameter is about 140 A. This is the first description of thermophilic nitrifying bacteria belonging to the genus Nitrosomonas.

Hot Temperature↗

PubMed2006

Community structures and activities of nitrifying and denitrifying bacteria in industrial wastewater-treating biofilms.

The bacterial community structure, in situ spatial distributions and activities of nitrifying and denitrifying bacteria in biofilms treating industrial wastewater were investigated by combination of the 16S rRNA gene clone analysis, fluorescence in situ hybridization (FISH) and microelectrodes. These results were compared with the nitrogen removal capacity of the industrial wastewater treatment plant (IWTP). Both nitrification and denitrification occurred in the primary denitrification (PD) tank and denitrification occurred in the secondary denitrification (SD) tank. In contrast, nitrification and denitrification rates were very low in the nitrification (N) tank. 16S rRNA gene clone sequence analysis revealed that the bacteria affiliated with Alphaproteobacteria, followed by Betaproteobacteria, were numerically important microbial groups in three tanks. The many clones affiliated with Alphaproteobacteria were closely related to the denitrifying bacteria (e.g., Hyphomicrobium spp., Rhodopseudomonas palustris, and Rhodobacter spp.). In addition, Methylophilus leisingeri affiliated with Betaproteobacteria, which favorably utilized methanol, was detected only in the SD-tank to which methanol was added. Nitrosomonas europaea and Nitrosomonas marina were detected as the ammonia-oxidizing bacteria affiliated with Betaproteobacteria throughout this plant, although the dominant species of them was different among three tanks. Nitrifying bacteria were mainly detected in the upper parts of the PD-biofilm whereas their populations were low in the upper parts of the N-biofilm. The presence of denitrifying bacteria affiliated with Hyphomicrobium spp. in SD- and N-biofilms was verified by FISH analysis. Microelectrode measurements showed that the nitrifying bacteria present in the N- and PD-biofilms were active and the bacteria present in the SD-biofilm could denitrify.

Bacteria↗

PubMed1998

Organic halogen removal from chlorinated humic ground water and lake water by nitrifying fluidized-bed biomass characterised by electron microscopy and molecular methods.

The dechlorinating and genotoxicity-removing activities of nitrifying fluidized-bed reactor biomass towards chlorinated organic compounds in water were shown at level below 1 ppm. The removal rates of adsorbable organic halogens were 200 micrograms Cl (g VS day)-1 for chlorinated humic ground water and 50 micrograms Cl (g VS day)-1 for chlorinated lake water when studied in batch mode. In a sequenced batch mode the removal rates [micrograms Cl (g VS day)-1] were 2000 from chlorohumus, 1400-1800 from chlorophenols in chlorinated ground water, and 430-720 from chlorohumus in chlorinated lake water. Genotoxicity was removed to a large extent (60%-80%) from the chlorinated waters upon incubation with nitrifying reactor biomass. 2,6-Di-, 2,4,6-tri and 2,3,4,6-tetrachlorophenols competed with chlorinated water organohalogens for dechlorination. The dechlorination of chlorophenols and chlorohumus required no ammonia and was not prevented by inhibitors of ammonia oxidation, nitrapyrin, parathion, sodium diethyldithiocarbamate, or allylthiourea. Electron microscopical inspection of the biomass showed the dominance of clusters of bacteria resembling known nitrifying species, Nitrosomonas, Nitrobacter, and Nitrosospira. This was supported by polymerase chain reaction amplification of the biomass DNA with four different primers, revealing the presence of 16S rDNA sequences assignable to the same species. The most intensive band obtained with the Nitroso4E primer was shown to be closely related to Nitrosomonas europaea by restriction analysis.

Ammonia↗

PubMed1991

Quantitative structure-activity relationships for chemical toxicity to environmental bacteria.

Quantitative structure-activity relationships (QSARs) were developed for nonreactive chemical toxicity to each of four groups of bacteria of importance in environmental engineering: aerobic heterotrophs, methanogens, Nitrosomonas, and Microtox. The QSARs were based on chemicals covering a range of structures and including important environmental pollutants (i.e., chlorinated and other substituted benzenes, phenols, and aliphatic hydrocarbons). QSARs were developed for each chemical class and for combinations of chemical classes. Three QSAR methods (groups of chemical describing parameters) were evaluated for their accuracy and ease of use: log P, linear solvation energy relationships (LSER), and molecular connectivity. Successful QSARs were found for each group of bacteria and by each method, with correlation coefficients (adjusted r2) between 0.79 and 0.95. LSER QSARs incorporated the widest range of chemicals with the greatest accuracy. Log P and molecular connectivity QSARs are easier to use because their parameters are readily available. Outliers from the QSARs likely due to reactive toxicity included acryls, low pKa compounds, and aldehydes. Nitro compounds and chlorinated aliphatic hydrocarbons and alcohols showed enhanced toxicity to the methanogens only. Chemicals with low IC50 concentrations (log IC50 mumol/liter less than 1.5) were often outliers for Nitrosomonas. QSARs were validated statistically and with literature data. A suggested method is provided for use of the QSARs.

Bacteria↗

PubMed2004

Phylogenetic analysis of nitric oxide reductase gene homologues from aerobic ammonia-oxidizing bacteria.

Nitric oxide (NO) and nitrous oxide (N2O) are climatically important trace gases that are produced by both nitrifying and denitrifying bacteria. In the denitrification pathway, N2O is produced from nitric oxide (NO) by the enzyme nitric oxide reductase (NOR). The ammonia-oxidizing bacterium Nitrosomonas europaea also possesses a functional nitric oxide reductase, which was shown recently to serve a unique function. In this study, sequences homologous to the large subunit of nitric oxide reductase (norB) were obtained from eight additional strains of ammonia-oxidizing bacteria, including Nitrosomonas and Nitrosococcus species (i.e., both beta- and gamma-Proteobacterial ammonia oxidizers), showing widespread occurrence of a norB homologue in ammonia-oxidizing bacteria. However, despite efforts to detect norB homologues from Nitrosospira strains, sequences have not yet been obtained. Phylogenetic analysis placed nitrifier norB homologues in a subcluster, distinct from denitrifier sequences. The similarities and differences of these sequences highlight the need to understand the variety of metabolisms represented within a "functional group" defined by the presence of a single homologous gene. These results expand the database of norB homologue sequences in nitrifying bacteria.

Aerobiosis↗

PubMed2005

Effect of salinity on temporal and spatial dynamics of ammonia-oxidising bacteria from intertidal freshwater sediment.

Temporal and spatial dynamics within an ammonia-oxidising community from intertidal, freshwater sediments were studied in microcosms simulating flooding twice a day with fresh, brackish and marine waters. The microcosms had been filled with the upper 5 cm of intertidal freshwater sediment from the river Scheldt. Changes in community composition were examined by denaturing gradient gel electrophoresis of amplified DNA from the community. In the first week of incubation the initially present members of the Nitrosomonas oligotropha lineage were replaced by other members of the same lineage in the top layer of the sediment subjected to flooding with freshwater. Prolonged incubation extended niche differentiation to a depth of 5 cm. In the microcosms flooded with saline media, the initially present members of the N. oligotropha lineage were replaced by strains belonging to the Nitrosomonas marina lineage, but only in the top 1cm. Shift in community composition occurred earlier in the marine microcosms than in the brackish microcosms and was slower than the change in the freshwater microcosms. Irrespective of the nature of the flooding medium, shifts in community composition were always consistent among replicate microcosms. We conclude that salinity is an important steering factor in niche differentiation among ammonia-oxidising bacteria and also that changes within the community of this functional group of bacteria may occur at different rates.

Ammonia↗

PubMed2004

Two kinds of ammonia-oxidizing bacteria isolated from biologically deodorizing plants in cold district.

Two kinds of ammonia-oxidizing bacteria isolated from biologically deodorizing plants in cold districts in Japan were identified as Nitrosomonas sp. IWT202 and Nitrosomonas sp. IWT514. The optimum pHs for growth were 8.0 (IWT202) and 7.5 (IWT514). Although rockwool samples for isolation were collected from the same plants, the optimum temperature for growth of strain IWT202 (37 degrees C) differed from that of strain IWT514 (30 degrees C). The bacteria had a higher (IWT202, 37 degrees C) and lower (IWT514, 20 degrees C) growth temperature than is usually the case. Both strains were shown to differ completely in regard to the effect of the ammonium sulfate concentration in the medium for a 20 degrees C culture and 30 degrees C culture. The inoculation of these bacteria provides the possibility of recovering ammonia-oxidizing activity, when the ammonia-oxidizing activity is lowered in biological deodorizing plants in cold districts. It seems that these strains are suitable for application to deodorization.

Journal Article↗

PubMed2002

In situ characterization of nitrifiers in an activated sludge plant: detection of Nitrobacter Spp.

AIMS: The purpose of this work was to investigate microbial ecology of nitrifiers at the genus level in a typical full-scale activated sludge plant. METHODS AND RESULTS: Grab samples of mixed liquor were collected from a plug-flow reactor receiving domestic wastewater. Fluorescent in situ hybridization technique (FISH) was used to characterize both ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) in combination with Confocal Scanning Laser Microscope (CSLM). Fluorescently labelled, 16S rRNA-targeted oligonucleotide probes were used in this study. Both Nitrosomonas and Nitrosospira genera as AOB and Nitrobacter and Nitrospira genera as NOB were sought with genus specific probes Nsm156, Nsv443 and NIT3 and NSR1156, respectively. CONCLUSIONS: It was shown that Nitrosospira genus was dominant in the activated sludge system studied, although Nitrosomonas is usually assumed to be the dominant genus. At the same time, Nitrobacter genus was detected in activated sludge samples. SIGNIFICANCE AND IMPACT OF THE STUDY: Previous studies based on laboratory scale pilot plants employing synthetic wastewater suggested that only Nitrospira are found in wastewater treatment plants. We have shown that Nitrobacter genus might also be present. We think that these kinds of studies may not give a valid indication of the microbial diversity of the real full-scale plants fed with domestic wastewater.

Ammonia↗

PubMed2005

Links between ammonia oxidizer species composition, functional diversity and nitrification kinetics in grassland soils.

Molecular approaches have revealed considerable diversity and uncultured novelty in natural prokaryotic populations, but not direct links between the new genotypes detected and ecosystem processes. Here we describe the influence of the structure of communities of ammonia-oxidizing bacteria on nitrogen cycling in microcosms containing natural and managed grasslands and amended with artificial sheep urine, a major factor determining local ammonia concentrations in these environments. Nitrification kinetics were assessed by analysis of changes in urea, ammonia, nitrite and nitrate concentrations and ammonia oxidizer communities were characterized by analysis of 16S rRNA genes amplified from extracted DNA using ammonia oxidizer-specific primers. In natural soils, ammonia oxidizer community structure determined the delay preceding nitrification, which depended on the relative abundance of two Nitrosospira clusters, termed 3a and 3b. In batch cultures, pure culture and enrichment culture representatives of Nitrosospira 3a were sensitive to high ammonia concentration, while Nitrosospira cluster 3b representatives and Nitrosomonas europaea were tolerant. Delays in nitrification occurred in natural soils dominated by Nitrosospira cluster 3a and resulted from the time required for growth of low concentrations of Nitrosospira cluster 3b. In microcosms dominated by Nitrosospira cluster 3b and Nitrosomonas, no substantial delays were observed. In managed soils, no delays in nitrification were detected, regardless of initial ammonia oxidizer community structure, most probably resulting from higher ammonia oxidizer cell concentrations. The data therefore demonstrate a direct link between bacterial community structure, physiological diversity and ecosystem function.

Ammonia↗

PubMed2005

Loss of diversity of ammonia-oxidizing bacteria correlates with increasing salinity in an estuary system.

Ammonia-oxidizing bacteria (AOB) play an important role in nitrogen cycling in estuaries, but little is known about AOB diversity, distribution and activity in relation to the chemical and physical changes encountered in estuary systems. Although estuarine salinity gradients are well recognized to influence microbial community structure, few studies have examined the influence of varying salinity on the diversity and stability of AOB populations. To investigate these relationships, we collected sediment samples from low-, mid- and high-salinity sites in Plum Island Sound estuary, MA, during spring and late summer over 3 years. Ammonia-oxidizing bacteria distribution and diversity were assessed by terminal restriction fragment length polymorphism (TRFLP) analysis of the ammonia monooxygenase (amoA) gene, and fragments were identified by screening amoA clone libraries constructed from each site. Most striking was the stability and low diversity of the AOB community at the high-salinity site, showing little variability over 3 years. Ammonia-oxidizing bacteria at the high-salinity site were not closely related to any cultured AOB, but were most similar to Nitrosospira spp. Ammonia-oxidizing bacteria at the mid- and low-salinity sites were distributed among Nitrosospira-like sequences and sequences related to Nitrosomonas ureae/oligotropha and Nitrosomonas sp. Nm143. Our study suggests that salinity is a strong environmental control on AOB diversity and distribution in this estuary.

Ammonia↗

PubMed2005

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). Biofilm thin sections were subjected to fluorescence in situ hybridization (FISH), microautoradiography (MAR), and local quantification of [14C]-bicarbonate uptake (beta microimaging). Nitrifying activity and tracer assimilation were restricted to a surface layer of different thickness in the various experiments (substrate or oxygen limitation). Excess oxygen uptake under all conditions revealed heterotrophic activity fuelled by decay or excretion products during active nitrification. Depth limits and intensity of tracer incorporation profiles were in agreement with ammonia-oxidation activity (measured with microsensors), and distribution of incorporated tracer (detected with MAR). Microautoradiography revealed a sharp individual response of distinct populations in terms of in-/activity depending on the (local) environmental conditions within the biofilm. Net in situ carbon yields on N, expressed as e- equivalent ratios, varied between 0.005 and 0.018, and, thus, were in the lower range of data reported for pure cultures of nitrifiers.

Ammonia↗

PubMed1998

The anaerobic oxidation of ammonium.

From recent research it has become clear that at least two different possibilities for anaerobic ammonium oxidation exist in nature. 'Aerobic' ammonium oxidizers like Nitrosomonas eutropha were observed to reduce nitrite or nitrogen dioxide with hydroxylamine or ammonium as electron donor under anoxic conditions. The maximum rate for anaerobic ammonium oxidation was about 2 nmol NH4+ min-1 (mg protein)-1 using nitrogen dioxide as electron acceptor. This reaction, which may involve NO as an intermediate, is thought to generate energy sufficient for survival under anoxic conditions, but not for growth. A novel obligately anaerobic ammonium oxidation (Anammox) process was recently discovered in a denitrifying pilot plant reactor. From this system, a highly enriched microbial community with one dominating peculiar autotrophic organism was obtained. With nitrite as electron acceptor a maximum specific oxidation rate of 55 nmol NH4+ min-1 (mg protein)-1 was determined. Although this reaction is 25-fold faster than in Nitrosomonas, it allowed growth at a rate of only 0.003 h-1 (doubling time 11 days). 15N labeling studies showed that hydroxylamine and hydrazine were important intermediates in this new process. A novel type of hydroxylamine oxidoreductase containing an unusual P468 cytochrome has been purified from the Anammox culture. Microsensor studies have shown that at the oxic/anoxic interface of many ecosystems nitrite and ammonia occur in the absence of oxygen. In addition, the number of reports on unaccounted high nitrogen losses in wastewater treatment is gradually increasing, indicating that anaerobic ammonium oxidation may be more widespread than previously assumed. The recently developed nitrification systems in which oxidation of nitrite to nitrate is prevented form an ideal partner for the Anammox process. The combination of these partial nitrification and Anammox processes remains a challenge for future application in the removal of ammonium from wastewater with high ammonium concentrations.

Anaerobiosis↗

PubMed1978

Diversity in the ammonia-oxidizing nitrifier population of a soil.

Multiple genera of ammonia-oxidizing chemoautotrophic nitrifiers in a soil were detected, isolated, and studied by means of modified most-probable-number (MPN) techniques. The soil examined was a Waukegon silt loam treated with ammonium nitrate or sewage effluent. The genera Nitrosomonas and Nitrosospira were found to occur more commonly than the genus Nitrosolobus. Three different MPN media gave approximately the same overall ammonia oxidizer counts within statistical error after prolonged incubation but differed markedly in ratios of Nitrosomonas to Nitrosospira. Selectivity and counting efficiency of MPN media were studied by observing the growth response of representative pure cultures isolated from the soil. Selectivity was evident in each medium with respect to all strains tested, and the media differed greatly in incubation times required to obtain maximum counts.

Journal Article↗

PubMed1980

Production of NO(2) and N(2)O by Nitrifying Bacteria at Reduced Concentrations of Oxygen.

Pure cultures of the marine ammonium-oxidizing bacterium Nitrosomonas sp. were grown in the laboratory at oxygen partial pressures between 0.005 and 0.2 atm (0.18 to 7 mg/liter). Low oxygen conditions induced a marked decrease in the rate for production of NO(2), from 3.6 x 10 to 0.5 x 10 mmol of NO(2) per cell per day. In contrast, evolution of N(2)O increased from 1 x 10 to 4.3 x 10 mmol of N per cell per day. The yield of N(2)O relative to NO(2) increased from 0.3% to nearly 10% (moles of N in N(2)O per mole of NO(2)) as the oxygen level was reduced, although bacterial growth rates changed by less than 30%. Nitrifying bacteria from the genera Nitrosomonas, Nitrosolobus, Nitrosospira, and Nitrosococcus exhibited similar yields of N(2)O at atmospheric oxygen levels. Nitrite-oxidizing bacteria (Nitrobacter sp.) and the dinoflagellate Exuviaella sp. did not produce detectable quantities of N(2)O during growth. The results support the view that nitrification is an important source of N(2)O in the environment.

Journal Article↗

PubMed1980

Production of nitrous oxide by ammonia-oxidizing chemoautotrophic microorganisms in soil.

Gas chromatographic studies showed that nitrous oxide was produced in each instance when sterilized (autoclaved) soil was incubated after treatment with ammonium sulfate and inoculation with pure cultures of ammonia-oxidizing chemoautotrophic microorganisms (strains of Nitrosomonas, Nitrosospira, and Nitrosolobus). Production of N(2)O in ammonium-treated sterilized soil inoculated with Nitrosomonas europaea increased with the concentration of ammonium and the moisture content of the soil and was completely inhibited by both nitrapyrin and acetylene. Similar effects of nitrapyrin, acetylene, ammonium concentration, and soil moisture content were observed in studies of factors affecting N(2)O production in nonsterile soil treated with ammonium sulfate. These observations support the conclusion that, at least under some conditions, most of the N(2)O evolved from soils treated with ammonium or ammonium-producing fertilizers is generated by chemoautotrophic nitrifying microorganisms during oxidation of ammonium to nitrite.

Journal Article↗