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1.
Chem Commun (Camb) ; 58(61): 8540-8543, 2022 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-35815642

RESUMO

A fluorescent probe for phenylhydrazine detection was developed with aldehyde as the recognition group and good selectivity towards phenylhydrazine over hydrazine, hydroxylamine and other amines was observed. Its application in real water samples and fast visualization of phenylhydrazine using a probe-loaded paper strip were demonstrated.


Assuntos
Colorimetria , Corantes Fluorescentes , Fluorometria , Hidroxilamina , Fenil-Hidrazinas
2.
Arch Biochem Biophys ; 726: 109247, 2022 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-35667906

RESUMO

Accompanying the autoxidation of hydroxylamine at pH 10.2, nitroblue tetrazolium was reduced and nitrite was produced in the presence of EDTA. The rate of autoxidation was negligible below pH 8.0, but sharply increased with increasing pH. The reduction of nitroblue tetrazolium was inhibited by superoxide dismutase, indicating the participation of superoxide anion radical in the autoxidation. Hydrogen peroxide stimulated the autoxidation and superoxide dismutase inhibited the hydrogen peroxide-induced oxidation, results which suggest the participation of hydrogen peroxide in autoxidation and in the generation of superoxide radical. An assay for superoxide dismutase using autoxidation of hydroxylamine is described.


Assuntos
Peróxido de Hidrogênio , Superóxidos , Hidroxilamina , Hidroxilaminas , Nitroazul de Tetrazólio , Oxirredução , Superóxido Dismutase/metabolismo
3.
Environ Sci Technol ; 56(14): 10317-10328, 2022 07 19.
Artigo em Inglês | MEDLINE | ID: mdl-35761213

RESUMO

Given hydroxylamine accumulation in various nitrification systems and its potential mechanism in regulating the subsequent denitrification process were unraveled in this study. Hydroxylamine (>0.5 mgN/L) immediately induced nitrite accumulation of activated sludge by inhibiting the activities of nitrite reductases and their electron transport modules (Complex III and cytochrome c). Moreover, long-term exposure to 0.5-2.5 mgN/L hydroxylamine accelerated the functional transformation from denitrification to denitratation under low C/N conditions. However, genome-centric metagenomics indicated that a genotypic complete rather than truncated denitrifier Thauera aminoaromatica TJ127 was enriched and mainly responsible for acetate storage and nitrate reduction of the denitratation community. Interestingly, its enrichment resulted in nitrite production and reduction sequentially but reduced nitrate only to nitrite under carbon-limited conditions (C/N ≤ 3.0). Thus, it showed higher tolerance to hydroxylamine than the concurrent phenotype denitrifiers in activated sludge. Moreover, due to its higher anoxic storage capability in the feast phase, this enrichment became highly specialized by decreasing the feast/famine ratio, and thus a satisfactory denitratation performance was still maintained without hydroxylamine. These results suggested that the transient release of hydroxylamine from nitrification may interfere with subsequent denitrification metabolism, but its continuous accumulation is beneficial for achieving denitratation, which could steadily provide nitrite for mainstream anammox.


Assuntos
Desnitrificação , Nitritos , Reatores Biológicos , Hidroxilamina , Hidroxilaminas , Cinética , Metagenômica , Nitratos , Nitrogênio , Oxirredução , Esgotos , Águas Residuárias
4.
J Environ Manage ; 316: 115237, 2022 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-35568014

RESUMO

NO and N2O as important greenhouse gases andtheir production mechanisms during nitrification are not completely understood. This study aimed to analyze the effect of hydroxylamine (NH2OH) on NO and N2O produced by nitrifying bacteria from activated sludge in a sequencing batch reactor (SBR). Experimental results showed that when nitrite (NO2-) accumulated during aerobic ammonia (NH4+) oxidation, N2O was the main product. The total amount of NO and N2O produced by NH2OH oxidation was positively correlated with dissolved oxygen (DO) levels. The imbalance of NH4+ oxidation caused by NH2OH addition was more conducive to the generation of NO and N2O under high DO conditions. When NH2OH was added into the reactor with NO2- as the substrate, the production of NO and N2O under high DO levels was mainly related to NH2OH oxidation. Under low DO conditions, NO and N2O from the biotic/abiotic hybrid pathways were more significant in the reactor of the coexistence of NO2- and NH2OH, which could be mainly caused by the pathways of nitrifier denitrification and abiotic reaction. Besides, limited amount of NO and N2O was generated by heterotrophic denitrification pathway during autotrophic nitrification. The implications for the above results are important for understanding the production of NO and N2O under NH2OH stress in nitrifying sludge reactor.


Assuntos
Reatores Biológicos , Esgotos , Reatores Biológicos/microbiologia , Desnitrificação , Hidroxilamina/metabolismo , Hidroxilaminas , Nitrificação , Dióxido de Nitrogênio , Óxido Nitroso/análise , Oxirredução , Oxigênio , Esgotos/microbiologia
5.
Anal Bioanal Chem ; 414(17): 5009-5022, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35641641

RESUMO

In this study, a fluorescent reagent, 4-((aminooxy)methyl)-7-hydroxycoumarin (AOHC), was for the first time applied to label the low-molecular-mass aldehydes (LMMAs) through reductive oxyamination reaction to afford single N,O-substituted oxyamine derivatives at room temperatures with derivatization efficiencies as high as 96.8%. In the following high-performance liquid chromatography with fluorescence detection analysis, 12 LMMAs, including furfurals, aromatic aldehydes, and aliphatic aldehydes, were baseline-separated on an ODS column and detected with low limits of detection (LODs) (0.2-50 nM), and good precisions (intraday relative standard deviations [RSDs] were 2.40-4.68%, and interday RSDs were 4.65-8.91%). This approach was then adopted to analyze six alcoholic beverages and five dairy products, and nine LMMAs with concentrations in the 0.28-798.16 µM range were successfully detected with excellent accuracies (recoveries were 92.2-106.2%). Finally, the results were statistically analyzed and discussed. The proposed method has several advantages, including high sensitivity, room-temperature labeling, and the avoidance of further extraction and/or enrichment procedures, demonstrating its great utility for monitoring LMMAs in various complex matrices.


Assuntos
Aldeídos , Bebidas , Aldeídos/análise , Bebidas/análise , Cromatografia Líquida de Alta Pressão/métodos , Hidroxilamina , Hidroxilaminas/análise , Indicadores e Reagentes
6.
Bioresour Technol ; 355: 127271, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35526711

RESUMO

The inhibitory roles of hydroxylamine (NH2OH) and hydrazine (N2H4) on nitrite-oxidizing bacteria were investigated in a comparative study. The results showed that nitrite accumulation was achieved by adding 5 mg-N/L NH2OH or N2H4 to two parallel sequencing batch reactors, with nitrite accumulation rate reaching 95.83% and 86.58% within 15 days after adopting aeration time control, respectively. Correspondingly, the maximum level of NO in typical cycles caused by NH2OH addition was 0.18 mg-N/L, which was higher than obtained for N2H4. NH2OH or N2H4 showed strong inhibition on Nitrospira and promoted the enrichment of Nitrosomonas, with the effects of NH2OH being more significant. However, nitritation began to deteriorate after the cessation of inhibitors addition. In conclusion, NH2OH was a better inhibitor than N2H4 for Nitrospira. The inhibitory role of NH2OH was primarily related to NO toxicity, while for N2H4 it was attributed to its own toxicity, with NO playing a smaller role.


Assuntos
Nitrificação , Nitritos , Amônia , Bactérias , Reatores Biológicos/microbiologia , Hidrazinas , Hidroxilamina/farmacologia , Hidroxilaminas , Oxirredução
7.
Chem Commun (Camb) ; 58(45): 6534-6537, 2022 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-35579352

RESUMO

Herein, we have developed a copper-catalyzed hydroaminocarbonylation of benzylidenecyclopropanes under relatively mild conditions. A series of γ,δ-unsaturated amides with a broad range of functional groups were obtained in moderate to good yields. Both dialkyl-substituted and monoalkyl-substituted hydroxylamine derivatives can be applied in this transformation to give the corresponding tertiary and secondary amides successfully.


Assuntos
Amidas , Cobre , Catálise , Hidroxilamina , Estrutura Molecular
8.
Water Res ; 216: 118315, 2022 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-35378450

RESUMO

Hydroxylamine (NH2OH) has been verified to efficiently strengthen pollutants oxidation in Fe(II)/peroxydisulfate (PDS) and Fe(II)/H2O2 systems. However, the different effects of hydroxylamine salts types were rarely recognized. Herein, the effects of two commonly used hydroxylamine salts (i.e. NH2OH·HCl and (NH2OH)2·H2SO4) on oxidation kinetics and reactive species composition were compared in Fe(II)/PDS and Fe(II)/H2O2 systems for the first time. Pseudo first order kinetics could only describe benzoic acid (BA) oxidation well in Fe(II)/NH2OH/H2O2 system, which was related to the different concentration changes of Fe(III) determined by [Formula: see text] . Hydroxylamine salts types influenced not kinetic rules, but reaction rates of target compounds. The empirical reaction rate constant of BA in Fe(II)/NH2OH·HCl/PDS system was 141.5% of that in Fe(II)/(NH2OH)2·H2SO4/PDS system under the same concentration of NH2OH (1.4 mM), while the apparent reaction rate constant in Fe(II)/NH2OH·HCl/H2O2 system was 68% of that in Fe(II)/(NH2OH)2·H2SO4/H2O2 system. This opposite effect resulted from the differences in primary reactive species compositions and their interactions with Cl-. Reactive species identification indicated that Cl- would decrease the contribution of ferryl ion (Fe(IV)) and transform sulfate radical (SO4·-) to hydroxyl radical (·OH) in Fe(II)/NH2OH/PDS system, while it competitively consumed the only reactive species ·OH in Fe(II)/NH2OH/H2O2 system. This study highlights the importance of reductants types on strengthening Fenton oxidation and offers a reference for reasonable construction of the relevant systems.


Assuntos
Compostos Férricos , Peróxido de Hidrogênio , Compostos Ferrosos , Hidroxilamina , Hidroxilaminas , Oxirredução , Sais
9.
J Pharm Biomed Anal ; 214: 114736, 2022 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-35338944

RESUMO

A possibility of application of solid-phase analytical derivatization (SPAD) for the quantification of seven steroid hormones (testosterone, dihydrotestosterone, cortisone, cortisol, progesterone, 11α-hydroxyprogesterone, and estrone) in human urine was evaluated. To prepare urine samples for instrumental analysis, SPAD with hydroxylamine was applied after enzymatic hydrolysis of the sample. To achieve high recovery values, extraction and derivatization conditions were optimized. Cartridges packed with end-capped octadecylsilyl silica sorbent provided optimum extraction of target analytes, while the reaction with hydroxylamine in the cartridge was found as a simple and efficient way for the chemical derivatization of steroids. The obtained derivatives were detected by using reversed-phase ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry. The proposed procedure was validated and applied to the analysis of real urine samples to prove the applicability of the proposed method for the routine analysis.


Assuntos
Extração em Fase Sólida , Espectrometria de Massas em Tandem , Cromatografia Líquida de Alta Pressão/métodos , Hormônios , Humanos , Hidroxilamina , Limite de Detecção , Extração em Fase Sólida/métodos , Esteroides/química , Espectrometria de Massas em Tandem/métodos
10.
J Inorg Biochem ; 231: 111779, 2022 06.
Artigo em Inglês | MEDLINE | ID: mdl-35287039

RESUMO

Hydroxylamine (NH2OH) and its N-substituted derivatives (RNHOH) are important biological intermediates in the global N cycle. Heme plays a central role in the binding and activation of these hydroxylamines. We report the crystal structures of N-hydroxyamphetamine (AmphNHOH) in complex with Fe and Co heme models. We demonstrate a previously unrecognized internal H-bond interaction between a hydroxylamine RNHO-H group and a porphyrin N-atom. We utilize density functional theoretical (DFT) calculations to show that the conformations with the internal H-bond represent global minima along the potential energy surfaces for both the Fe and Co heme models. A natural bond orbital (NBO) analysis reveals a donor π (porN=C) to acceptor σ* (O-H) interaction of 3.04 kcal/mol for Fe, accounting for 11% of the total heme-AmphNHOH interaction energy. Our DFT calculations with the parent Fe-NH2OH suggests that the presence of internal H-bonds between hydroxylamine (R/H)NHOH moieties and heme N-atoms may be more common than previously recognized.


Assuntos
Porfirinas , Anfetaminas , Teoria da Densidade Funcional , Heme/química , Hidroxilamina , Ferro/química , Porfirinas/química
11.
Bioresour Technol ; 350: 126912, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35231598

RESUMO

To overcome a large amount of nitrite accumulation and poor removal rate for hydroxylamine, a simultaneous nitrification and denitrification (SND) bacterium was isolated and identified as Pseudomonas taiwanensis EN-F2 by DNA sequencing. Strain EN-F2 could remove 100% of ammonium (52.90 mg/L), 100% of hydroxylamine (23.32 mg/L), 86.99% of nitrite (56.32 mg/L) and 89.21% of nitrate (56.18 mg/L) with a maximum removal rate of 8.72, 2.12, 4.55 and 5.80 mg/L/h, respectively. Ammonium and hydroxylamine could be preferentially removed during the SND process. The nitrite removal rate and cell growth were substantially enhanced by 2.10 mg/L/h and 0.45 after supplementation of hydroxylamine. The specific activities of ammonia monooxygenase (AMO), hydroxylamine oxidoreductase (HAO), nitrate reductase (NR), nitrite reductase (NIR) were successfully detected as 0.95, 0.31, 0.42 and 0.03 U/mg protein, respectively. All results demonstrated that strain EN-F2 could perform SND to remove multiple nitrogen sources from wastewater.


Assuntos
Compostos de Amônio , Nitrificação , Aerobiose , Compostos de Amônio/metabolismo , Desnitrificação , Processos Heterotróficos , Hidroxilamina , Hidroxilaminas , Nitritos/metabolismo , Nitrogênio , Pseudomonas
12.
Appl Environ Microbiol ; 88(7): e0241621, 2022 04 12.
Artigo em Inglês | MEDLINE | ID: mdl-35285242

RESUMO

In the nitrogen (N) cycle, nitrogenous compounds are chemically and biologically converted to various aqueous and gaseous N species. The 15N-labeling approach is a powerful culture-dependent technique to obtain insights into the complex nitrogen transformation reactions that occur in cultures. In the 15N-labeling approach, the fates of supplemented 15N- and/or unlabeled gaseous and aqueous compounds are tracked by mass spectrometry (MS) analysis, whereas MS analysis of aqueous N species requires laborious sample preparation steps and is performed using isotope-ratio mass spectrometry, which requires an expensive mass spectrometer. We developed a simple and high-throughput MS method for determining the 15N atoms percent of NH4+, NO2-, NO3-, NH2OH, and N2H4, where liquid samples (<0.5 mL) were mixed with colorimetric reagents (naphthylethylenediamine for NO2-, indophenol for NH4+, and p-aminobenzaldehyde for N2H4), and the mass spectra of the formed N complex dyes were obtained by matrix-assisted laser desorption ionization-time-of-flight (MALDI-TOF) MS. NH2OH and NO3- were chemically converted to NO2- by iodine oxidation and copper/hydrazine reduction reaction, respectively, prior to the above colorimetric reaction. The intensity of the isotope peak (M + 1 or M + 2) increased when the N complex dye was formed by coupling with a 15N-labeled compound, and a linear relationship was found between the determined 15N/14N peak ratio and 15N atom% for the tested N species. The developed method was applied to bacterial cultures to examine their N-transformation reactions, enabling us to observe the occurrence of NO2- oxidation and NO3- reduction in a hypoxic Nitrobacter winogradskyi culture. IMPORTANCE 15N/14N analysis for aqueous N species is a powerful tool for obtaining insights into the global N cycle, but the procedure is cumbersome and laborious. The combined use of colorimetric reagents and MALDI-TOF MS, designated color MALDI-TOF MS, enabled us to determine the 15N atom% of common aqueous N species without laborious sample preparation and chromatographic separation steps; for instance, the 15N atom% of NO2- can be determined from >1,000 liquid samples daily at <$1 (U.S.) per 384 samples for routine analysis. This convenient MS method is a powerful tool that will advance our ability to explore the N-transformation reactions that occur in various environments and biological samples.


Assuntos
Nitratos , Nitritos , Colorimetria , Hidrazinas , Hidroxilamina , Isótopos , Lasers , Nitrogênio , Dióxido de Nitrogênio , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos
13.
Bioresour Technol ; 351: 126926, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35272034

RESUMO

The NH2OH dosing strategy for nitrogen removal was investigated in a single return continuous-flow anaerobic/aerobic/anoxic/aerobic (AnOAO) reactor fed with real municipal wastewater. A high nitrite accumulation ratio of 98% was achieved in only two days by continuously adding 10 mg/L NH2OH. When gradually reducing dosing frequency to one day every four days, effluent total nitrogen was as low as 4.8 ± 2.2 mg N/L with removal efficiency of 88.7 ± 5.3%, under aerobic HRT of 4.6 h, DO below 1.0 mg/L, and C/N of 2.8 without external carbon sources. Batch test showed that nitrite oxidizing bacteria (NOB) activity decreased by 81% after adding NH2OH, while ammonia oxidizing bacteria (AOB) activity remained stable. qPCR confirmed that NOB abundance decreased, and 16S rRNA sequencing further showed that g_Nitrospira belonging to NOB decreased significantly (P < 0.001). Overall, this study provides a novel strategy for advanced nitrogen removal from municipal wastewater in continuous flow systems.


Assuntos
Microbiota , Águas Residuárias , Anaerobiose , Bactérias , Reatores Biológicos/microbiologia , Desnitrificação , Hidroxilamina , Nitrificação , Nitritos , Nitrogênio , Oxirredução , RNA Ribossômico 16S
14.
J Hazard Mater ; 429: 128380, 2022 05 05.
Artigo em Inglês | MEDLINE | ID: mdl-35121297

RESUMO

The heterogeneous Fenton-like process using pyrite (FeS2) is increasingly recognized as a promising advanced oxidation process for removal of organic contaminants. However, the slow regeneration of Fe(II) limits the generation of reactive oxygen species for environment implication. To overcome this drawback, hydroxylamine was applied to enhance the reactivity of FeS2 to degrade organic contaminants under oxic conditions. Results showed that hydroxylamine facilitated the regeneration of Fe(II) on FeS2 surface to promote reactive oxygen species generation, thereby efficiently degrading different organic contaminants. The underlying mechanism was further elucidated that the presence of hydroxylamine enhanced electron transfer from FeS2 to O2 to produce superoxide radicals (O2•-), hydrogen peroxide (H2O2) and hydroxyl radical (HO•) via Fenton-like pathways, which induced the rapid degradation of organic contaminants (e.g., sulfamethoxazole (SMX)). The reactivity of FeS2 for organic contaminant degradation changed negligibly after seven cycles in the presence of hydroxylamine. The effects of pH and inorganic anions on SMX degradation were also clarified in details. The finding of this study would provide a novel strategy to enhance the contaminants degradation by FeS2-based advanced oxidation technologies for environmental remediation.


Assuntos
Peróxido de Hidrogênio , Radical Hidroxila , Hidroxilamina , Hidroxilaminas , Ferro , Oxirredução , Sulfetos
15.
Anal Chem ; 94(8): 3590-3599, 2022 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-35171578

RESUMO

Monosaccharides play important roles in biological processes. Sensitive and accurate analyses of monosaccharides remain challenging because of their high hydrophilicities and poor ionization efficiencies. Here, we developed a paired derivatization approach with H/D-labeled hydroxylamines for simultaneous quantification of 12 monosaccharides by liquid chromatography tandem mass spectrometry (LC-MS/MS). O-(4-Methoxybenzyl)hydroxylamine hydrochloride (4-MOBHA·HCl) showed higher derivatization efficiency for monosaccharides compared to six other hydroxylamine analogues. The derivatization of monosaccharides was readily achieved in an aqueous solution. Furthermore, the deuterium-labeled isotope reagent, d3-4-MOBHA·HCl, was newly synthesized to stably label monosaccharides to improve its accuracy and precision in complex matrix analysis. As a result, 12 monosaccharides were rapidly detected by LC-MS/MS within 16 min with significant improvements in chromatographic separation and retention time. The detection sensitivity increased by 83 to 1600-fold with limits of quantitation ranging from 0.25 to 3.00 fmol. With the paired derivatization strategy, the monosaccharides could be accurately quantified with good linearity (R2 > 0.99) and satisfactory accuracy (recoveries: 85-110%). Using this method, we achieved sensitive and accurate quantification of the monosaccharide composition of herbal polysaccharides and the change in monosaccharide levels in human cell lines under physiopathological conditions. More importantly, the developed method was able to differentiate between the levels of the monosaccharides in fecal samples of human ulcerative colitis (UC) patients and UC mice compared to their respective controls. The differential monosaccharides determined in human feces provided a good diagnostic performance in distinguishing the UC patients from healthy individuals, showing potential for clinical application.


Assuntos
Monossacarídeos , Espectrometria de Massas em Tandem , Animais , Cromatografia Líquida de Alta Pressão/métodos , Cromatografia Líquida , Humanos , Hidroxilamina , Hidroxilaminas , Indicadores e Reagentes , Camundongos , Monossacarídeos/análise , Espectrometria de Massas em Tandem/métodos
16.
Environ Sci Pollut Res Int ; 29(20): 30285-30296, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-34997517

RESUMO

Production of hydroxyl radicals (•OH) upon the oxidation of solid Fe(II) by O2 or H2O2 in soils and sediments has been confirmed, which benefits in situ remediation of contaminants. However, Fe(III) reduction by H2O2 is rate-limiting. Accelerating the Fe(III)/Fe(II) cycle could improve the efficiency of remediation. This study intended to use hydroxylamine to promote Fe(III)/Fe(II) cycle during 100 g/L soil oxidation by H2O2 for phenol degradation. The removal of phenol was 76% in 3 h during soil oxidation with 1 mM H2O2 in the presence of 1 mM hydroxylamine but was negligible in the absence of hydroxylamine. Fe(III) in the soil was reduced to 0.21 mM Fe(II) by 1 mM hydroxylamine in 30 min. The accelerated cycle of Fe(III)/Fe(II) in the soil by hydroxylamine could effectively decompose H2O2 to produced •OH, which was responsible for the effective enhancement of phenol degradation during soil oxidation. Under the conditions of 1 mM H2O2 and 100 g/L soil, the pseudo-first-order kinetic constant of phenol degradation increased proportionally from 0.0453 to 0.0844 min-1 with the increase of hydroxylamine concentrations from 0.5 to 1 mM. The kinetic constant also increased from 0.0041 to 0.0111 min-1 with H2O2 concentration increased from 0.5 to 2 mM, while it decreased from 0.0100 to 0.0051 min-1 with soil dosage increased from 20 to 200 g/L. In addition, column experiments showed that phenol (10 mg/L) degradation ratio kept at about 48.7% with feeding 2 mM hydroxylamine and 2 mM H2O2 at 0.025 PV/min. Column experiments suggested an optional application of hydroxylamine and H2O2 for in situ remediation. The output of this study provides guidance and optional strategies to enhance contaminant degradation during soil oxidation.


Assuntos
Peróxido de Hidrogênio , Fenol , Compostos Ferrosos , Hidroxilamina , Ferro , Oxirredução , Fenóis , Solo
17.
Chemosphere ; 288(Pt 1): 132475, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34624339

RESUMO

Hydroxylamine, an intermediate product in the nitrification process, is widely found in nature. However, hydroxylamine accumulation can decrease the biological nitrogen removal efficiency by reducing the activities, inhibiting the reproductions, and even causing the death of microorganisms. In this study, a novel heterotrophic nitrification bacterium was separated from biogas digester and identified as Glutamicibacter arilaitensis EM-H8. Strain EM-H8 exhibited efficient hydroxylamine removal (93.75%). The optimal conditions for hydroxylamine removal were as follows: Carbon source, glucose; C/N ratio, 25; temperature, 20 °C; inoculum size, 0.53 × 108 CFU; and shaking speed, 150 rpm. The nitrogen balance results using strain EM-H8 showed that about 26.86% of the initial nitrogen was removed as nitrogenous gas, while 4.6% was converted into biomass under aerobic conditions, confirming that strain EM-H8 possessed the capacity for heterotrophic nitrification. Furthermore, the successful expression of hydroxylamine oxidase (0.065 U/mg protein) showed that strain EM-H8 had the ability to transform hydroxylamine from wastewater.


Assuntos
Desnitrificação , Nitrificação , Aerobiose , Processos Heterotróficos , Hidroxilamina , Hidroxilaminas , Micrococcaceae , Nitritos , Nitrogênio
18.
J Hazard Mater ; 421: 126736, 2022 01 05.
Artigo em Inglês | MEDLINE | ID: mdl-34333411

RESUMO

Nitrogen removal from mainstream wastewater via DEnitrifying AMmonium OXidation (DEAMOX) is often challenged by undulated actual temperature and high loading rate. Here, we discovered NH2OH addition (HA) and bio-augmentation (BA) tactics on start-up and operation performance of DEAMOXs (R1 and R2) under ambient temperature (11.3-31.7 °C). Over 340-day operation suggested that R2 received 10 mg/L HA and 1:25 BA ratio (v/v, anammox/partial denitrification sludge) achieved desirable nitrogen removal efficiency (NRE) of 97.22% after 145-day, while R1 under higher BA ratio of 1:12.5 without HA obtained lower NRE (90.86%) after 184-day. Batch tests revealed that nitrate-nitrite transformation ratio reached 98.64% at low COD/NO3--N of 2.6 with HA. Significantly, compared with R2, R1 recovered quickly with satisfactory effluent total nitrogen of 4.21 mg/L despite nitrogen loading rate greater than 0.15 kg N/m3/d and temperature decreased to 14.6 °C. The abundant narG represented high nitrate reduction potential, hzsA and hdh were extensively detected as the symbolisation of anammox metabolism. Thauera, Denitratisoma and unclassified f Comamonadaceae dominated nitrite accumulation. Ca. Brocadia as the dominant anammox bacteria, and its population maintained stable against low temperature and load shocks by NH2OH intensification. Overall, this study offers an opportunity for the wide-applications of DEAMOX treating mainstream wastewater.


Assuntos
Compostos de Amônio , Desnitrificação , Reatores Biológicos , Hidroxilamina , Hidroxilaminas , Nitrogênio/análise , Oxirredução , Esgotos , Temperatura , Águas Residuárias
19.
Sci Rep ; 11(1): 23105, 2021 11 29.
Artigo em Inglês | MEDLINE | ID: mdl-34845321

RESUMO

Alcaligenes faecalis is a heterotrophic nitrifying bacterium that oxidizes ammonia and generates nitrite and nitrate. When A. faecalis was cultivated in a medium containing pyruvate and ammonia as the sole carbon and nitrogen sources, respectively, high concentrations of nitrite accumulated in the medium whose carbon/nitrogen (C/N) ratio was lower than 10 during the exponential growth phase, while the accumulation was not observed in the medium whose C/N ratio was higher than 15. Comparative transcriptome analysis was performed using nitrifying and non-nitrifying cells of A. faecalis cultivated in media whose C/N ratios were 5 and 20, respectively, to evaluate the fluctuations of gene expression during induction of heterotrophic nitrification. Expression levels of genes involved in primary metabolism did not change significantly in the cells at the exponential growth phase under both conditions. We observed a significant increase in the expression levels of four gene clusters: pod cluster containing the gene encoding pyruvic oxime dioxygenase (POD), podh cluster containing the gene encoding a POD homolog (PODh), suf cluster involved in an iron-sulfur cluster biogenesis, and dnf cluster involved in a novel hydroxylamine oxidation pathway in the nitrifying cells. Our results provide valuable insight into the biochemical mechanism of heterotrophic nitrification.


Assuntos
Alcaligenes faecalis/genética , Alcaligenes faecalis/metabolismo , Regulação Bacteriana da Expressão Gênica , Processos Heterotróficos , Nitrificação , Amônia/metabolismo , Análise por Conglomerados , Perfilação da Expressão Gênica , Hidroxilamina/química , Família Multigênica , Nitratos/metabolismo , Nitritos/metabolismo , Nitrogênio/metabolismo , Propionatos/metabolismo , Transcriptoma
20.
Water Res ; 207: 117796, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34736001

RESUMO

In this study, a commonly used reducing agent, hydroxylamine (HA), was introduced into Fe(II)/PAA process to improve its oxidation capacity. The HA/Fe(II)/PAA process possessed high oxidation performance for diclofenac degradation even with trace Fe(II) dosage (i.e., 1 µM) at pH of 3.0 to 6.0. Based on electron paramagnetic resonance technology, methyl phenyl sulfoxide (PMSO)-based probe experiments and alcohol quenching experiments, FeIVO2+ and carbon-centered radicals (R-O•) were considered as the primary reactive species responsible for diclofenac elimination. HA accelerated the redox cycle of Fe(III)/Fe(II) and itself was gradually decomposed to N2, N2O, NO2- and NO3-, and the environmentally friendly gas of N2 was considered as the major decomposition product of HA. Four possible degradation pathways of diclofenac were proposed based on seven detected intermediate products. Both elevated dosages of Fe(II) and PAA promoted diclofenac removal. Cl-, HCO3- and SO42- had negligible impacts on diclofenac degradation, while humic acid exhibited an inhibitory effect. The oxidation capacity of HA/Fe(II)/PAA process in natural water matrices and its application to degrade various micropollutants were also investigated. This study proposed a promising strategy for improving the Fe(II)/PAA process and highlighted its potential application in water treatment.


Assuntos
Ácido Peracético , Poluentes Químicos da Água , Diclofenaco , Compostos Férricos , Compostos Ferrosos , Peróxido de Hidrogênio , Hidroxilamina , Hidroxilaminas , Oxirredução
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