Environmentally friendly synthesis of CeO2 nanoparticles for the catalytic oxidation of benzyl alcohol to benzaldehyde and selective detection of nitrite

PubMed Central

Tamizhdurai, P.; Sakthinathan, Subramanian; Chen, Shen-Ming; Shanthi, K.; Sivasanker, S.; Sangeetha, P.

2017-01-01

Cerium oxide nanoparticles (CeO2 NPs) are favorable in nanotechnology based on some remarkable properties. In this study, the crystalline CeO2 NPs are successfully prepared by an efficient microwave combustion (MCM) and conventional route sol-gel (CRSGM) methods. The structural morphology of the as-prepared CeO2 NPs was investigated by various spectroscopic and analytical techniques. Moreover, the XRD pattern confirmed the formation of CeO2 NPs as a face centered cubic structure. The magnetometer studies indicated the low saturation magnetization (23.96 emu/g) of CeO2 NPs for weak paramagnetic and high saturation magnetization (32.13 emu/g) of CeO2 NPs for super paramagnetic. After that, the oxidation effect of benzyl alcohol was investigated which reveals good conversion and selectivity. Besides, the CeO2 NPs modified glassy carbon electrode (GCE) used for the detection of nitrite with linear concentration range (0.02–1200 μM), low limit of detection (0.21 μM) and higher sensitivity (1.7238 μAμM−1 cm−2). However, the CeO2 NPs modified electrode has the fast response, high sensitivity and good selectivity. In addition, the fabricated electrode is applied for the determination of nitrite in various water samples. Eventually, the CeO2 NPs can be regarded as an effective way to enhance the catalytic activity towards the benzyl alcohol and nitrite. PMID:28406231

Sensitive naked eye detection and quantification assay for nitrite by a fluorescence probe in various water resources

NASA Astrophysics Data System (ADS)

Zhang, Fengyuan; Zhu, Xinyue; Jiao, Zhijuan; Liu, Xiaoyan; Zhang, Haixia

2018-07-01

An uncontrolled increase of nitrite concentration in groundwater, rivers and lakes is a growing threat to public health and environment. It is important to monitor the nitrite levels in water and clinical diagnosis. Herein, we developed a switch-off fluorescence probe (PyI) for the sensitive detection of nitrite ions in the aqueous media. This probe selectively recognizes nitrite ions through a distinct visual color change from colorless to pink with a detection limit of 0.1 μM. This method has been successfully applied to the determination of nitrites in tap water, lake water and Yellow River water with recoveries in the range of 94.8%-105.4%.

ARM-microcontroller based portable nitrite electrochemical analyzer using cytochrome c reductase biofunctionalized onto screen printed carbon electrode.

PubMed

Santharaman, Paulraj; Venkatesh, Krishna Arun; Vairamani, Kanagavel; Benjamin, Alby Robson; Sethy, Niroj K; Bhargava, Kalpana; Karunakaran, Chandran

2017-04-15

Nitrite (NO 2 - ) supplementation limits hypoxia-induced oxidative stress and activates the alternate NO pathway which may partially account for the nitrite-mediated cardioprotection. So, sensitive and selective biosensors with point-of-care devices need to be explored to detect the physiological nitrite level due to its important role in human pathophysiology. In this work, cytochrome c reductase (CcR) biofunctionalized self assembled monolayer (SAM) functionalized on gold nanoparticles (GNPs) in polypyrrole (PPy) nanocomposite onto the screen printed carbon electrode (SPCE) was investigated as a biosensor for the detection of nitrite based on its electrochemical and catalytic properties. CcR was covalently coupled with SAM layers on GNPs by using EDC and NHS. Direct electrochemical response of CcR biofunctionalized electrodes showed a couple of well-defined and nearly reversible cyclic voltammetric peaks at -0.34 and -0.45 vs. Ag/AgCl. Under optimal conditions, the biosensor could be used for the determination of NO 2 - with a linear range from 0.1-1600µm and a detection limit of 60nM with a sensitivity of 0.172µAµM -1 cm -2 . Further, we have designed and developed a novel and cost effective portable electrochemical analyzer for the measurement of NO 2 - in hypoxia induced H9c2 cardiac cells using ARM microcontroller. The results obtained here using the developed portable electrochemical nitrite analyzer were also compared with the standard cyclic voltammetry instrument and found in agreement with each other. Copyright © 2016 Elsevier B.V. All rights reserved.

Rapid visual and spectrophotometric nitrite detection by cyclometalated ruthenium complex.

PubMed

Lo, Hoi-Shing; Lo, Ka-Wai; Yeung, Chi-Fung; Wong, Chun-Yuen

2017-10-16

Quantitative determination of nitrite ion (NO 2 - ) is of great importance in environmental and clinical investigations. A rapid visual and spectrophotometric assay for NO 2 - detection was developed based on a newly designed ruthenium complex, [Ru(npy)([9]aneS3)(CO)](ClO 4 ) (denoted as RuNPY; npy = 2-(1-naphthyl)pyridine, [9]aneS3 = 1,4,7-trithiacyclononane). This complex traps NO + produced in acidified NO 2 - solution, and yields observable color change within 1 min at room temperature. The assay features excellent dynamic range (1-840 μmol L -1 ) and high selectivity, and its limit of detection (0.39 μmol L -1 ) is also well below the guideline values for drinking water recommended by WHO and U.S. EPA. Practical use of this assay in tap water and human urine was successfully demonstrated. Overall, the rapidity and selectivity of this assay overcome the problems suffered by the commonly used modified Griess assays for nitrite determination. Copyright © 2017 Elsevier B.V. All rights reserved.

An improved method to measure nitrate/nitrite with an NO-selective electrochemical sensor

PubMed Central

Boo, Yong Chool; Tressel, Sarah L.; Jo, Hanjoong

2007-01-01

Nitric oxide produced from nitric oxide synthase(s) is an important cell signaling molecule in physiology and pathophysiology. In the present study, we describe a very sensitive and convenient analytical method to measure NOx (nitrite plus nitrate) in culture media by employing an ultra-sensitive nitric oxide-selective electrochemical sensor which became commercially available recently. An aliquot of conditioned culture media was first treated with nitrate reductase/NADPH/glucose-6-phosphate dehydrogenase/glucose-6-phosphate to convert nitrate to nitrite quantitatively. The nitrite (that is present originally plus the reduced nitrate) was then reduced to equimolar NO in an acidic iodide bath while NO was being detected by the sensor. This analytical method appears to be very useful to assess basal and stimulated NO release from cultured cells. PMID:17056288

A simple gold plate electrode modified with Gd-doped TiO₂ nanoparticles used for determination of trace nitrite in cured food.

PubMed

Zhang, M-L; Cao, Z; He, J-L; Xue, L; Zhou, Y; Long, S; Deng, T; Zhang, L

2012-01-01

A simple gold plate electrode (GPE) based on a gadolinium-doped titanium dioxide (Gd/TiO₂) ultrathin film was successfully constructed by using a surface sol-gel technique, and used for the detection of trace amounts of nitrite in cured foods. The Gd/TiO₂ nanoparticles were synthesised and characterised via scanning electron microscopy (SEM) and X-ray diffraction (XRD), indicating that the Gd-doped TiO₂ formed an anatase phase through roasting at 450°C, generating actively interstitial oxygen at the interface of the surface of TiO₂ lattice surrounded by Gd³⁺. The electro-catalytic effect for oxidation of nitrite on the modified electrode was investigated by cyclic voltammetry in 0.10 mol l⁻¹ sulfuric acid media solution, showing that the modified electrode exhibited excellent response performance to nitrite with good reproducibility, selectivity and stability. The catalytic peak current was found to be linear with nitrite concentrations in the range of 8.0 × 10⁻⁷ to 4.0 × 10⁻⁴) mol l⁻¹, with a detection limit of 5.0 × 10⁻⁷ mol l⁻¹ (S/N = 3). The modified electrode could be used for the determination of nitrite in the cured sausage samples with a satisfactory recovery in the range of 95.5-104%, showing its promising application for food safety monitoring.

A new electrochemical sensor for highly sensitive and selective detection of nitrite in food samples based on sonochemical synthesized Calcium Ferrite (CaFe2O4) clusters modified screen printed carbon electrode.

PubMed

Balasubramanian, Paramasivam; Settu, Ramki; Chen, Shen-Ming; Chen, Tse-Wei; Sharmila, Ganapathi

2018-08-15

Herein, we report a novel, disposable electrochemical sensor for the detection of nitrite ions in food samples based on the sonochemical synthesized orthorhombic CaFe 2 O 4 (CFO) clusters modified screen printed electrode. As synthesized CFO clusters were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transformer infrared spectroscopy (FT-IR), Thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and amperometry (i-t). Under optimal condition, the CFO modified electrode displayed a rapid current response to nitrite, a linear response range from 0.016 to 1921 µM associated with a low detection limit 6.6 nM. The suggested sensor also showed the excellent sensitivity of 3.712 μA μM -1  cm -2 . Furthermore, a good reproducibility, long-term stability and excellent selectivity were also attained on the proposed sensor. In addition, the practical applicability of the sensor was investigated via meat samples, tap water and drinking water, and showed desirable recovery rate, representing its possibilities for practical application. Copyright © 2018 Elsevier Inc. All rights reserved.

Sensitive naked eye detection and quantification assay for nitrite by a fluorescence probe in various water resources.

PubMed

Zhang, Fengyuan; Zhu, Xinyue; Jiao, Zhijuan; Liu, Xiaoyan; Zhang, Haixia

2018-07-05

An uncontrolled increase of nitrite concentration in groundwater, rivers and lakes is a growing threat to public health and environment. It is important to monitor the nitrite levels in water and clinical diagnosis. Herein, we developed a switch-off fluorescence probe (PyI) for the sensitive detection of nitrite ions in the aqueous media. This probe selectively recognizes nitrite ions through a distinct visual color change from colorless to pink with a detection limit of 0.1 μM. This method has been successfully applied to the determination of nitrites in tap water, lake water and Yellow River water with recoveries in the range of 94.8%-105.4%. Copyright © 2018 Elsevier B.V. All rights reserved.

Nitrite spray treatment to promote red color stability of vacuum packaged beef.

PubMed

Song, Xiao; Cornforth, Daren; Whittier, Dick; Luo, Xin

2015-01-01

Sodium nitrite solutions were sprayed on select grade boneless rib (M. longissimus thoracis) and bottom round (mainly M. biceps femoris) steaks individually, to form bright red nitric oxide myoglobin (NO-Mb) in vacuum packages. Our objective was to determine the optimum level of nitrite in spray for stable raw steak redness, low or no residual nitrite, and low surface pinking (ham-like cured color) after cooking. Results showed that steaks sprayed with 100-350 ppm nitrite solutions had 3.0-3.6g weight gain and a calculated level of 1.3-5.3mg nitrite added/kg steak, but very low (<1 ppm) residual nitrite. Nitrite sprays of 250-350 ppm were optimum for raw steak color during 21 days of storage at 1°C (a*>10; chroma C*>16). Raw steak redness was less stable in round than rib. Visual scores for pinkness after cooking were low, indicating that cooked color at even the highest nitrite treatment (350 ppm) was acceptable. Copyright © 2014 Elsevier Ltd. All rights reserved.

Assessment of dietary exposure in the French population to 13 selected food colours, preservatives, antioxidants, stabilizers, emulsifiers and sweeteners.

PubMed

Bemrah, Nawel; Leblanc, Jean-Charles; Volatier, Jean-Luc

2008-01-01

The results of French intake estimates for 13 food additives prioritized by the methods proposed in the 2001 Report from the European Commission on Dietary Food Additive Intake in the European Union are reported. These 13 additives were selected using the first and second tiers of the three-tier approach. The first tier was based on theoretical food consumption data and the maximum permitted level of additives. The second tier used real individual food consumption data and the maximum permitted level of additives for the substances which exceeded the acceptable daily intakes (ADI) in the first tier. In the third tier reported in this study, intake estimates were calculated for the 13 additives (colours, preservatives, antioxidants, stabilizers, emulsifiers and sweeteners) according to two modelling assumptions corresponding to two different food habit scenarios (assumption 1: consumers consume foods that may or may not contain food additives, and assumption 2: consumers always consume foods that contain additives) when possible. In this approach, real individual food consumption data and the occurrence/use-level of food additives reported by the food industry were used. Overall, the results of the intake estimates are reassuring for the majority of additives studied since the risk of exceeding the ADI was low, except for nitrites, sulfites and annatto, whose ADIs were exceeded by either children or adult consumers or by both populations under one and/or two modelling assumptions. Under the first assumption, the ADI is exceeded for high consumers among adults for nitrites and sulfites (155 and 118.4%, respectively) and among children for nitrites (275%). Under the second assumption, the average nitrites dietary exposure in children exceeds the ADI (146.7%). For high consumers, adults exceed the nitrite and sulfite ADIs (223 and 156.4%, respectively) and children exceed the nitrite, annatto and sulfite ADIs (416.7, 124.6 and 130.6%, respectively).

Difficulties in maintaining long-term partial nitritation of ammonium-rich sludge digester liquids in a moving-bed biofilm reactor (MBBR).

PubMed

Fux, C; Huang, D; Monti, A; Siegrist, H

2004-01-01

Nitrogen can be eliminated effectively from sludge digester effluents by anaerobic ammonium oxidation (anammox), but 55-60% of the ammonium must first be oxidized to nitrite. Although a continuous flow stirred tank reactor (CSTR) with suspended biomass could be used, its hydraulic dilution rate is limited to 0.8-1 d(-1) (30 degrees C). Higher specific nitrite production rates can be achieved by sludge retention, as shown here for a moving-bed biofilm reactor (MBBR) with Kaldnes carriers on laboratory and pilot scales. The maximum nitrite production rate amounted to 2.7 gNO2-Nm(-2)d(-1) (3 gO2m(-3)d(-1), 30.5 degrees C), thus doubling the dilution rate compared to CSTR operation with suspended biomass for a supernatant with 700 gNH4-Nm(-3). Whenever the available alkalinity was fully consumed, an optimal amount of nitrite was produced. However, a significant amount of nitrate was produced after 11 months of operation, making the effluent unsuitable for anaerobic ammonium oxidation. Because the sludge retention time (SRT) is relatively long in biofilm systems, slow growth of nitrite oxidizers occurs. None of the selection criteria applied - a high ammonium loading rate, high free ammonia or low oxygen concentration - led to selective suppression of nitrite oxidation. A CSTR or SBR with suspended biomass is consequently recommended for full-scale operation.

Regulation of nitrite transport in red blood cells by hemoglobin oxygen fractional saturation.

PubMed

Vitturi, Dario A; Teng, Xinjun; Toledo, José C; Matalon, Sadis; Lancaster, Jack R; Patel, Rakesh P

2009-05-01

Allosteric regulation of nitrite reduction by deoxyhemoglobin has been proposed to mediate nitric oxide (NO) formation during hypoxia. Nitrite is predominantly an anion at physiological pH, raising questions about the mechanism by which it enters the red blood cell (RBC) and whether this is regulated and coupled to deoxyhemoglobin-mediated reduction. We tested the hypothesis that nitrite transport by RBCs is regulated by fractional saturation. Using human RBCs, nitrite consumption was faster at lower fractional saturations, consistent with faster reactions with deoxyheme. A membrane-based regulation was suggested by slower nitrite consumption with intact versus lysed RBCs. Interestingly, upon nitrite addition, intracellular nitrite concentrations attained a steady state that, despite increased rates of consumption, did not change with decreasing oxygen tensions, suggesting a deoxygenation-sensitive step that either increases nitrite import or decreases the rate of nitrite export. A role for anion exchanger (AE)-1 in the control of nitrite export was suggested by increased intracellular nitrite concentrations in RBCs treated with DIDS. Moreover, deoxygenation decreased steady-state levels of intracellular nitrite in AE-1-inhibited RBCs. Based on these data, we propose a model in which deoxyhemoglobin binding to AE-1 inhibits nitrite export under low oxygen tensions allowing for the coupling between deoxygenation and nitrite reduction to NO along the arterial-to-venous gradient.

Maternal dietary intake of nitrates, nitrites and nitrosamines and selected birth defects in offspring: a case-control study

PubMed Central

2013-01-01

Background Dietary intake of nitrates, nitrites, and nitrosamines can increase the endogenous formation of N-nitroso compounds in the stomach. Results from animal studies suggest that these compounds might be teratogenic. We examined the relationship between maternal dietary intake of nitrates, nitrites (including plant and animal sources as separate groups), and nitrosamines and several types of birth defects in offspring. Methods For this population-based case–control study, data from a 58-question food frequency questionnaire, adapted from the short Willett Food Frequency Questionnaire and administered as part of the National Birth Defects Prevention Study (NBDPS), were used to estimate daily intake of dietary nitrates, nitrites, and nitrosamines in a sample of 6544 mothers of infants with neural tube defects (NTD)s, oral clefts (OC)s, or limb deficiencies (LD)s and 6807 mothers of unaffected control infants. Total daily intake of these compounds was divided into quartiles based on the control mother distributions. Odds ratios (OR)s and 95% confidence intervals (CI)s were estimated using logistic regression; estimates were adjusted for maternal daily caloric intake, maternal race-ethnicity, education, dietary folate intake, high fat diet (> 30% of calories from fat), and state of residence. Results While some unadjusted ORs for NTDS had 95% (CI)s that excluded the null value, none remained significant after adjustment for covariates, and the effect sizes were small (adjusted odds ratios [aOR] <1.12). Similar results were found for OCs and LDs with the exception of animal nitrites and cleft lip with/without cleft palate (aORs and CIs for quartile 4 compared to quartile 1 =1.24; CI=1.05-1.48), animal nitrites and cleft lip (4th quartile aOR=1.32; CI=1.01-1.72), and total nitrite and intercalary LD (4th quartile aOR=4.70; CI=1.23-17.93). Conclusions Overall, odds of NTDs, OCs or LDs did not appear to be significantly associated with estimated dietary intake of nitrate, nitrite, and nitrosamines. PMID:23514444

Maternal dietary intake of nitrates, nitrites and nitrosamines and selected birth defects in offspring: a case-control study.

PubMed

Huber, John C; Brender, Jean D; Zheng, Qi; Sharkey, Joseph R; Vuong, Ann M; Shinde, Mayura U; Griesenbeck, John S; Suarez, Lucina; Langlois, Peter H; Canfield, Mark A; Romitti, Paul A; Weyer, Peter J

2013-03-21

Dietary intake of nitrates, nitrites, and nitrosamines can increase the endogenous formation of N-nitroso compounds in the stomach. Results from animal studies suggest that these compounds might be teratogenic. We examined the relationship between maternal dietary intake of nitrates, nitrites (including plant and animal sources as separate groups), and nitrosamines and several types of birth defects in offspring. For this population-based case-control study, data from a 58-question food frequency questionnaire, adapted from the short Willett Food Frequency Questionnaire and administered as part of the National Birth Defects Prevention Study (NBDPS), were used to estimate daily intake of dietary nitrates, nitrites, and nitrosamines in a sample of 6544 mothers of infants with neural tube defects (NTD)s, oral clefts (OC)s, or limb deficiencies (LD)s and 6807 mothers of unaffected control infants. Total daily intake of these compounds was divided into quartiles based on the control mother distributions. Odds ratios (OR)s and 95% confidence intervals (CI)s were estimated using logistic regression; estimates were adjusted for maternal daily caloric intake, maternal race-ethnicity, education, dietary folate intake, high fat diet (>30% of calories from fat), and state of residence. While some unadjusted ORs for NTDS had 95% (CI)s that excluded the null value, none remained significant after adjustment for covariates, and the effect sizes were small (adjusted odds ratios [aOR]<1.12). Similar results were found for OCs and LDs with the exception of animal nitrites and cleft lip with/without cleft palate (aORs and CIs for quartile 4 compared to quartile 1 =1.24; CI=1.05-1.48), animal nitrites and cleft lip (4th quartile aOR=1.32; CI=1.01-1.72), and total nitrite and intercalary LD (4th quartile aOR=4.70; CI=1.23-17.93). Overall, odds of NTDs, OCs or LDs did not appear to be significantly associated with estimated dietary intake of nitrate, nitrite, and nitrosamines.

Biodegradability of fluoxetine, mefenamic acid, and metoprolol using different microbial consortiums.

PubMed

Velázquez, Yolanda Flores; Nacheva, Petia Mijaylova

2017-03-01

The biodegradation of fluoxetine, mefenamic acid, and metoprolol using ammonium-nitrite-oxidizing consortium, nitrite-oxidizing consortium, and heterotrophic biomass was evaluated in batch tests applying different retention times. The ammonium-nitrite-oxidizing consortium presented the highest biodegradation percentages for mefenamic acid and metoprolol, of 85 and 64% respectively. This consortium was also capable to biodegrade 79% of fluoxetine. The heterotrophic consortium showed the highest ability to biodegrade fluoxetine reaching 85%, and it also had a high potential for biodegrading mefenamic acid and metoprolol, of 66 and 58% respectively. The nitrite-oxidizing consortium presented the lowest biodegradation of the three pharmaceuticals, of less than 48%. The determination of the selected pharmaceuticals in the dissolved phase and in the biomass indicated that biodegradation was the major removal mechanism of the three compounds. Based on the obtained results, the biodegradation kinetics was adjusted to pseudo-first-order for the three pharmaceuticals. The values of k biol for fluoxetine, mefenamic acid, and metoprolol determined with the three consortiums indicated that ammonium-nitrite-oxidizing and heterotrophic biomass allow a partial biodegradation of the compounds, while no substantial biodegradation can be expected using nitrite-oxidizing consortium. Metoprolol was the less biodegradable compound. The sorption of fluoxetine and mefenamic acid onto biomass had a significant contribution for their removal (6-14%). The lowest sorption coefficients were obtained for metoprolol indicating that the sorption onto biomass is poor (3-4%), and the contribution of this process to the global removal can be neglected.

Nutritional value and potential chemical food safety hazards of selected Polish sausages as influenced by their traditionality.

PubMed

Halagarda, Michał; Kędzior, Władysław; Pyrzyńska, Ewa

2018-05-01

Traditional food products have been regaining consumer interest worldwide. The aim of the study was to investigate the differences in nutritional value of traditional and conventional Polish sausages and to determine potential chemical hazards connected with these products. The research material consisted of 5 varieties of registered traditional sausages and 4 varieties of conventional sausages. The nutritional value was identified based on selected indicators: protein, fat, NaCl, total ash, water, Feder's number, Ca, Fe, Mg, K, Zn, Cr, Cu; whereas the chemical food safety - based on: nitrates and nitrites, total and added phosphorus, Cd, Pb. The results of this study show that traditional sausages have higher content of protein, zinc, magnesium and potassium as well as lower concentrations of calcium, water and total ash, plus lower water to protein ratio in comparison to conventional counterparts. Polyphosphates are not used in the production of traditional sausages and the amounts of added nitrites are at low levels. Copyright © 2018 Elsevier Ltd. All rights reserved.

FORMATION OF NITRITE AND NITRATE BY ACTINOMYCETES AND FUNGI

PubMed Central

Hirsch, P.; Overrein, L.; Alexander, M.

1961-01-01

Hirsch, P. (Cornell University, Ithaca, New York), L. Overrein, and M. Alexander. Formation of nitrite and nitrate by actinomycetes and fungi. J. Bacteriol. 82:442–448. 1961.—Nitrite was produced by strains of Mycobacterium, Nocardia, Streptomyces, Micromonospora, and Streptosporangium in media containing ammonium phosphate as the sole nitrogen source. The quantity of nitrite formed was small, and the concentration was affected by pH and by the relative levels of carbon and nitrogen. Aspergillus flavus produced little nitrite from ammonium but formed in excess of 100 parts per million of nitrate-nitrogen. Peroxidase activity and heterotrophic nitrification were reduced in acid conditions, but mycelial development of the fungus was not markedly affected. The inability of A. flavus to form nitrate and nitrite at low pH appears to result from a selective effect of pH upon nitrification rather than being a consequence of the decomposition of nitrogenous intermediates. PMID:13714587

Evaluation of nitrite contamination in baby foods and infant formulas marketed in Turkey.

PubMed

Erkekoglu, Pinar; Baydar, Terken

2009-05-01

Nitrites are responsible for methemoglobinemia, to which infants younger than 6 months are thought to be the most susceptible population. This study aimed to detect whether there was any nitrite contamination in infant formulas and baby foods marketed in Turkey and to estimate possible toxicological risks in this sensitive physiological period. For this purpose, the samples were randomly collected and divided into four groups: milk-based, cereal-based, vegetable-based, and fruit-based. An easy and reliable spectrophotometric method was used by modifying the Griess method. The average nitrite contamination was found to be 204.07+/-65.80 microg/g in 42 samples, with 1,073 microg/g maximum. According to the results, baby and infant formulas include various nitrite levels; nitrite contamination might come from several sources during manufacturing, and so extreme attention must be given throughout the manufacturing process of food for infants.

Smartphone-based simultaneous pH and nitrite colorimetric determination for paper microfluidic devices.

PubMed

Lopez-Ruiz, Nuria; Curto, Vincenzo F; Erenas, Miguel M; Benito-Lopez, Fernando; Diamond, Dermot; Palma, Alberto J; Capitan-Vallvey, Luis F

2014-10-07

In this work, an Android application for measurement of nitrite concentration and pH determination in combination with a low-cost paper-based microfluidic device is presented. The application uses seven sensing areas, containing the corresponding immobilized reagents, to produce selective color changes when a sample solution is placed in the sampling area. Under controlled conditions of light, using the flash of the smartphone as a light source, the image captured with the built-in camera is processed using a customized algorithm for multidetection of the colored sensing areas. The developed image-processing allows reducing the influence of the light source and the positioning of the microfluidic device in the picture. Then, the H (hue) and S (saturation) coordinates of the HSV color space are extracted and related to pH and nitrite concentration, respectively. A complete characterization of the sensing elements has been carried out as well as a full description of the image analysis for detection. The results show good use of a mobile phone as an analytical instrument. For the pH, the resolution obtained is 0.04 units of pH, 0.09 of accuracy, and a mean squared error of 0.167. With regard to nitrite, 0.51% at 4.0 mg L(-1) of resolution and 0.52 mg L(-1) as the limit of detection was achieved.

Synthesis of Superparamagnetic Core-Shell Structure Supported Pd Nanocatalysts for Catalytic Nitrite Reduction with Enhanced Activity, No Detection of Undesirable Product of Ammonium, and Easy Magnetic Separation Capability.

PubMed

Sun, Wuzhu; Yang, Weiyi; Xu, Zhengchao; Li, Qi; Shang, Jian Ku

2016-01-27

Superparamagnetic nanocatalysts could minimize both the external and internal mass transport limitations and neutralize OH(-) produced in the reaction more effectively to enhance the catalytic nitrite reduction efficiency with the depressed product selectivity to undesirable ammonium, while possess an easy magnetic separation capability. However, commonly used qusi-monodispersed superparamagnetic Fe3O4 nanosphere is not suitable as catalyst support for nitrite reduction because it could reduce the catalytic reaction efficiency and the product selectivity to N2, and the iron leakage could bring secondary contamination to the treated water. In this study, protective shells of SiO2, polymethylacrylic acid, and carbon were introduced to synthesize Fe3O4@SiO2/Pd, Fe3O4@PMAA/Pd, and Fe3O4@C/Pd catalysts for catalytic nitrite reduction. It was found that SiO2 shell could provide the complete protection to Fe3O4 nanosphere core among these shells. Because of its good dispersion, dense structure, and complete protection to Fe3O4, the Fe3O4@SiO2/Pd catalyst demonstrated the highest catalytic nitrite reduction activity without the detection of NH4(+) produced. Due to this unique structure, the activity of Fe3O4@SiO2/Pd catalysts for nitrite reduction was found to be independent of the Pd nanoparticle size or shape, and their product selectivity was independent of the Pd nanoparticle size, shape, and content. Furthermore, their superparamagnetic nature and high saturation magnetization allowed their easy magnetic separation from treated water, and they also demonstrated a good stability during the subsequent recycling experiment.

Fluorometric determination of nitrite in cured meats.

PubMed

Coppola, E D; Wickroski, A F; Hanna, J G

1975-05-01

An indirect fluorometric method for determining sodium nitrite in meat products is presented. The extracted sodium nitrite is consumed in a diazotization reaction with a measured excess of sulfanilic acid. Fluorescamine, which acts selectively with primary amines such as sulfanilic acid, is a fluorogenic reagent for the excess amine. The amine consumed, calculated by difference from the total originally present, is directly related to the sodium nitrite content of the sample. Interferences from amino acids and soluble proteins in the meat extract are eliminated by judicious use of a secondary peak in the fluorescence spectra (436 nm excitation, 495 nm fluorescence) combined with measurement at low pH (3.30). The recoveries of sodium nitrite ranged from 83.2 to 99.6% with an average of 93.4 and a standard deviation of +/- 5.28% for 11 determinations.

Nitrite Biosensing via Selective Enzymes—A Long but Promising Route

PubMed Central

Almeida, M. Gabriela; Serra, Alexandra; Silveira, Celia M.; Moura, Jose J.G.

2010-01-01

The last decades have witnessed a steady increase of the social and political awareness for the need of monitoring and controlling environmental and industrial processes. In the case of nitrite ion, due to its potential toxicity for human health, the European Union has recently implemented a number of rules to restrict its level in drinking waters and food products. Although several analytical protocols have been proposed for nitrite quantification, none of them enable a reliable and quick analysis of complex samples. An alternative approach relies on the construction of biosensing devices using stable enzymes, with both high activity and specificity for nitrite. In this paper we review the current state-of-the-art in the field of electrochemical and optical biosensors using nitrite reducing enzymes as biorecognition elements and discuss the opportunities and challenges in this emerging market. PMID:22163541

Development and calibration of a dietary nitrate and nitrite database in the NIH–AARP Diet and Health Study

PubMed Central

Inoue-Choi, Maki; Virk-Baker, Mandeep K; Aschebrook-Kilfoy, Briseis; Cross, Amanda J; Subar, Amy F; Thompson, Frances E; Sinha, Rashmi; Ward, Mary H

2016-01-01

Objective Nitrate and nitrite are probable human carcinogens when ingested under conditions that increase the formation of N-nitroso compounds. There have been limited efforts to develop US databases of dietary nitrate and nitrite for standard FFQ. Here we describe the development of a dietary nitrate and nitrite database and its calibration. Design We analysed data from a calibration study of 1942 members of the NIH–AARP (NIH–AARP, National Institutes of Health–AARP) Diet and Health Study who reported all foods and beverages consumed on the preceding day in two non-consecutive 24 h dietary recalls (24HR) and completed an FFQ. Based on a literature review, we developed a database of nitrate and nitrite contents for foods reported on these 24HR and for food category line items on the FFQ. We calculated daily nitrate and nitrite intakes for both instruments, and used a measurement error model to compute correlation coefficients and attenuation factors for the FFQ-based intake estimates using 24HR-based values as reference data. Results FFQ-based median nitrate intake was 68·9 and 74·1 mg/d, and nitrite intake was 1·3 and 1·0 mg/d, in men and women, respectively. These values were similar to 24HR-based intake estimates. Energy-adjusted correlation coefficients between FFQ- and 24HR-based values for men and women respectively were 0·59 and 0·57 for nitrate and 0·59 and 0·58 for nitrite; energy-adjusted attenuation factors were 0·59 and 0·57 for nitrate and 0·47 and 0·38 for nitrite. Conclusions The performance of the FFQ in assessing dietary nitrate and nitrite intakes is comparable to that for many other macro- and micronutrients. PMID:26626817

Nitrogen removal performance and loading capacity of a novel single-stage nitritation-anammox system with syntrophic micro-granules.

PubMed

Wang, Shaopo; Liu, Yuan; Niu, Qigui; Ji, Jiayuan; Hojo, Toshimasa; Li, Yu-You

2017-07-01

The operation performance of a novel micro-granule based syntrophic system of nitritation and anammox was studied by controlling the oxygen concentration and maintaining a constant temperature of 25°C. With the oxygen concentration of around 0.11 (<0.15)mg/L, the single-stage nitritation-anammox system was startup successfully at a nitrogen loading rate (NLR) of 1.5kgN/m 3 /d. The reactor was successfully operated at volumetric N loadings ranging from 0.5 to 2.5kgN/m 3 /d with a high nitrogen removal of 82%. The microbial community was composed by ammonia oxidizing bacteria (AOB) and anammox bacteria forming micro-granules with an average diameter of 0.8mm and good settleability. Results from pyrosequencing analysis revealed that Ca. Kuenenia and Nitrosomonas were selected and enriched in the community over the startup period, and these were identified as the dominant anammox bacteria and AOB species, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

Utilization of urea, ammonia, nitrite, and nitrate by crop plants in a Controlled Ecological Life Support System (CELSS)

NASA Technical Reports Server (NTRS)

Huffaker, R. C.; Rains, D. W.; Qualset, C. O.

1982-01-01

The utilization of nitrogen compounds by crop plants is studied. The selection of crop varieties for efficient production using urea, ammonia, nitrite, and nitrate, and the assimilation of mixed nitrogen sources by cereal leaves and roots are discussed.

Nitrates and nitrites in selected vegetables purchased at supermarkets in Siedlce, Poland.

PubMed

Raczuk, Jolanta; Wadas, Wanda; Głozak, Katarzyna

2014-01-01

Vegetables constitute a vital part of the human diet, being the main source of minerals, vitamins, dietary fibre and phytochemicals. They however, also contain nitrates and nitrites, which adversely affect human health. To determine nitrate and nitrite content in selected vegetables purchased at supermarket chains in Siedlce and to assess their impact on consumer health. Vegetable samples were purchased from local supermarkets in Siedlce, town situated in the Mazovian province (Voivodeship) of Poland. These consisted of 116 samples of nine vegetables types including butterhead and iceberg lettuce, beetroot, white cabbage, carrot, cucumber, radish, tomato and potato collected between April and September 2011. Concentrations of nitrate and nitrite were determined by standard colorimetric methods used in Poland, with results expressed as mg per kg fresh weight of vegetables. Nitrate concentrations varied between 10 mg x kg(-1) to 4800 mg x kg(-1). The highest mean nitrate concentrations were found in radishes (2132 mgkg(-1)), butterhead lettuce (1725 mg x kg(-1)), beetroots (1306 mg x kg(-1)) and iceberg lettuce (890 mg x kg(-1)), whereas the lowest were found in cucumber (32 mg x kg(-1)) and tomato (35 mg x kg(-1)). Nitrite levels were also variable; the highest concentrations measured were in beetroot (mean 9.19 mg x kg(-1)) whilst much smaller amounts were present in carrot, cucumbers, iceberg lettuce, white cabbage, tomatoes and potatoes. The daily adult consumption of 100 g amounts of the studied vegetables were found not exceed the ADI for both nitrates and nitrites. Findings indicated the need for monitoring nitrate and nitrite content in radishes, butterhead lettuce and beetroot due to consumer health concerns.

Effect of selected organic and inorganic snow and cloud components on the photochemical generation of nitrite by nitrate irradiation.

PubMed

Minero, Claudio; Maurino, Valter; Bono, Francesca; Pelizzetti, Ezio; Marinoni, Angela; Mailhot, Gilles; Carlotti, Maria Eugenia; Vione, Davide

2007-08-01

The effect of selected organic and inorganic compounds, present in snow and cloudwater was studied. Photolysis of solutions of nitrate to nitrite was carried out in the laboratory using a UVB light source. The photolysis and other reactions were then modelled. It is shown that formate, formaldehyde, methanesulphonate, and chloride to a lesser extent, can increase the initial formation rate of nitrite. The effect, particularly significant for formate and formaldehyde, is unlikely to be caused by scavenging of hydroxyl radicals. The experimental data obtained in this work suggest that possible causes are the reduction of nitrogen dioxide and nitrate by radical species formed on photooxidation of the organic compounds. Hydroxyl scavenging by organic and inorganic compounds would not affect the initial formation rate of nitrite, but would protect it from oxidation, therefore, increasing the concentration values reached at long irradiation times. The described processes can be relevant to cloudwater and the quasi-liquid layer on the surface of ice and snow, considering that in the polar regions irradiated snow layers are important sources of nitrous acid to the atmosphere. Formate and (at a lesser extent) formaldehyde are the compounds that play the major role in the described processes of nitrite/nitrous acid photoformation by initial rate enhancement and hydroxyl scavenging.

Inorganic Nitrite Therapy: Historical perspective and future directions

PubMed Central

Kevil, Christopher G.; Kolluru, Gopi K.; Pattillo, Christopher B.; Giordano, Tony

2015-01-01

Over the past several years, investigators studying nitric oxide (NO) biology and metabolism have come to learn that the one electron oxidation product of NO, nitrite anion, serves as a unique player in modulating tissue NO bioavailability. Numerous studies have examined how this oxidized metabolite of NO can act as a salvage pathway for maintaining NO equivalents through multiple reduction mechanisms in permissive tissue environments. Moreover, it is now clear that nitrite anion production and distribution throughout the body can act in an endocrine manner to augment NO bioavailability that is important for physiological and pathological processes. These discoveries have led to renewed hope and efforts for an effective NO based therapeutic agent through the unique action of sodium nitrite as an NO pro-drug. More recent studies also indicate that sodium nitrate may also increase plasma nitrite levels via the enterosalivary circulatory system resulting in nitrate reduction to nitrite by microorganisms found within the oral cavity. In this review, we discuss the importance of nitrite anion in several disease models along with an appraisal of sodium nitrite therapy in the clinic, potential caveats of such clinical uses, and future possibilities of nitrite based therapies. PMID:21619929

Detection of nitrite based on fluorescent carbon dots by the hydrothermal method with folic acid

NASA Astrophysics Data System (ADS)

Lin, Haitao; Ding, Liyun; Zhang, Bingyu; Huang, Jun

2018-05-01

A fluorescent carbon dots probe for the detection of aqueous nitrite was fabricated by a one-pot hydrothermal method, and the transmission electron microscope, X-ray diffractometer, UV-Vis absorption spectrometer and fluorescence spectrophotometer were used to study the property of carbon dots. The fluorescent property of carbon dots influenced by the concentration of aqueous nitrite was studied. The interaction between the electron-donating functional groups and the electron-accepting nitrous acid could account for the quenching effect on carbon dots by adding aqueous nitrite. The products of the hydrolysis of aqueous nitrite performed a stronger quenching effect at lower pH. The relationship between the relative fluorescence intensity of carbon dots and the concentration of nitrite was described by the Stern-Volmer equation (I0/I - 1 = 0.046[Q]) with a fine linearity (R2 = 0.99). The carbon dots-based probe provides a convenient method for the detection of nitrite concentration.

Synthesis, characterization and nitrite ion sensing performance of reclaimable composite samples through a core-shell structure

NASA Astrophysics Data System (ADS)

Cui, Xiao; Yuqing, Zhao; Cui, Jiantao; Zheng, Qian; Bo, Wang

2018-02-01

The following paper reported and discussed a nitrite ion optical sensing platform based on a core-shell structure, using superamagnetic nanoparticles as the core, a silica molecular sieve MCM-41 as the shell and two rhodamine derivatives as probe, respectively. This superamagnetic core made this sensing platform reclaimable after finishing nitrite ion sensing procedure. This sensing platform was carefully characterized by means of electron microscopy images, porous structure analysis, magnetic response, IR spectra and thermal stability analysis. Detailed analysis suggested that the emission of these composite samples was quenchable by nitrite ion, showing emission turn off effect. A static sensing mechanism based on an additive reaction between chemosensors and nitrite ion was proposed. These composite samples followed Demas quenching equation against different nitrite ion concentrations. Limit of detection value was obtained as low as 0.4 μM. It was found that, after being quenched by nitrite ion, these composite samples could be reclaimed and recovered by sulphamic acid, confirming their recyclability.

Photodissociation dynamics of nitromethane and methyl nitrite by infrared multiphoton dissociation imaging with quasiclassical trajectory calculations: signatures of the roaming pathway.

PubMed

Dey, Arghya; Fernando, Ravin; Abeysekera, Chamara; Homayoon, Zahra; Bowman, Joel M; Suits, Arthur G

2014-02-07

We combine the techniques of infrared multiphoton dissociation (IRMPD) with state selective ion imaging to probe roaming dynamics in the unimolecular dissociation of nitromethane and methyl nitrite. Recent theoretical calculations suggest a "roaming-mediated isomerization" pathway of nitromethane to methyl nitrite prior to decomposition. State-resolved imaging of the NO product coupled with infrared multiphoton dissociation was carried out to examine this unimolecular decomposition near threshold. The IRMPD images for the NO product from nitromethane are consistent with the earlier IRMPD studies that first suggested the importance of an isomerization pathway. A significant Λ-doublet propensity is seen in nitromethane IRMPD but not methyl nitrite. The experimental observations are augmented by quasiclassical trajectory calculations for nitromethane and methyl nitrite near threshold for each dissociation pathway. The observation of distinct methoxy vibrational excitation for trajectories from nitromethane and methyl nitrite dissociation at the same total energy show that the nitromethane dissociation bears a nonstatistical signature of the roaming isomerization pathway, and this is possibly responsible for the nitromethane Λ-doublet propensity as well.

Biological Nitrogen Removal through Nitritation Coupled with Thiosulfate-Driven Denitritation

PubMed Central

Qian, Jin; Zhou, Junmei; Zhang, Zhen; Liu, Rulong; Wang, Qilin

2016-01-01

A novel biological nitrogen removal system based on nitritation coupled with thiosulfate-driven denitritation (Nitritation-TDD) was developed to achieve a high nitrogen removal rate and low sludge production. A nitritation sequential batch reactor (nitritation SBR) and an anoxic up-flow sludge bed (AnUSB) reactor were applied for effective nitritation and denitritation, respectively. Above 75% nitrite was accumulated in the nitritation SBR with an influent ammonia loading rate of 0.43 kg N/d/m3. During Nitritation-TDD operation, particle sizes (d50) of the sludge decreased from 406 to 225 um in nitritation SBR and from 327–183 um in AnUSB reactor. Pyrosequencing tests revealed that ammonium-oxidizing bacteria (AOB) population was stabilized at approximately 7.0% (calculated as population of AOB-related genus divided by the total microbial population) in the nitritation SBR. In contrast, nitrite-oxidizing bacteria (NOB) population decreased from 6.5–0.6% over the same time, indicating the effective nitrite accumulation in the nitritation SBR. Thiobacillus, accounting for 34.2% in the AnUSB reactor, was mainly responsible for nitrogen removal via autotrophic denitritation, using an external source of thiosulfate as electron donor. Also, it was found that free nitrous acid could directly affect the denitritation activity. PMID:27272192

Erythrocytes are the major intravascular storage sites of nitrite in human blood

PubMed Central

Dejam, André; Hunter, Christian J.; Pelletier, Mildred M.; Hsu, Lewis L.; Machado, Roberto F.; Shiva, Sruti; Power, Gordon G.; Kelm, Malte; Gladwin, Mark T.; Schechter, Alan N.

2005-01-01

Plasma levels of nitrite ions have been used as an index of nitric oxide synthase (NOS) activity in vivo. Recent data suggest that nitrite is a potential intravascular repository for nitric oxide (NO), bioactivated by a nitrite reductase activity of deoxyhemoglobin. The precise levels and compartmentalization of nitrite within blood and erythrocytes have not been determined. Nitrite levels in whole blood and erythrocytes were determined using reductive chemiluminescence in conjunction with a ferricyanide-based hemoglobin oxidation assay to prevent nitrite destruction. This method yields sensitive and linear measurements of whole blood nitrite over 24 hours at room temperature. Nitrite levels measured in plasma, erythrocytes, and whole blood from 15 healthy volunteers were 121 plus or minus 9, 288 plus or minus 47, and 176 plus or minus 17 nM, indicating a surprisingly high concentration of nitrite within erythrocytes. The majority of nitrite in erythrocytes is located in the cytosol unbound to proteins. In humans, we found a significant artery-to-vein gradient of nitrite in whole blood and erythrocytes. Shear stress and acetylcholine-mediated stimulation of endothelial NOS significantly increased venous nitrite levels. These studies suggest a dynamic intravascular NO metabolism in which endothelial NOS-derived NO is stabilized as nitrite, transported by erythrocytes, and consumed during arterial-to-venous transit. (Blood. 2005;106:734-739) PMID:15774613

The effects of elevated environmental CO2 on nitrite uptake in the air-breathing clown knifefish, Chitala ornata.

PubMed

Gam, Le Thi Hong; Jensen, Frank Bo; Huong, Do Thi Thanh; Phuong, Nguyen Thanh; Bayley, Mark

2018-03-01

Nitrite and carbon dioxide are common environmental contaminants in the intensive aquaculture ponds used to farm clown knifefish (Chitala ornata) in the Mekong delta, Vietnam. Here we tested the hypothesis that hypercapnia reduces nitrite uptake across the gills, because pH regulation will reduce chloride uptake and hence nitrite uptake as the two ions compete for the same transport route via the branchial HCO 3 - /Cl - exchanger. Fish fitted with arterial catheters were exposed to normocapnic/normoxic water (control), nitrite (1 mM), hypercapnia (21 mmHg CO 2 ), or combined hypercapnia (acclimated hypercapnia) and nitrite for 96 h. Blood was sampled to measure acid-base status, haemoglobin derivatives and plasma ions. Plasma nitrite increased for 48 h, but levels stayed below the exposure concentration, and subsequently decreased as a result of nitrite detoxification to nitrate. The total uptake of nitrite (evaluated as [NO 2 - ] + [NO 3 - ]) was significantly decreased in hypercapnia, in accordance with the hypothesis. Methemoglobin and nitrosylhemoglobin levels were similarly lower during hypercapnic compared to normocapnic nitrite exposure. The respiratory acidosis induced by hypercapnia was half-compensated by bicarbonate accumulation in 96 h, which was mainly chloride-mediated (i.e. reduced Cl - influx via the branchial HCO 3 - /Cl - exchanger). Plasma osmolality and main ions (Na + , Cl - ) were significantly decreased by hypercapnia and by nitrite exposure, consistent with inhibition of active transport. We conclude that hypercapnia induces a long-lasting, and mainly chloride-mediated acid-base regulation that reduces the uptake of nitrite across the gills. Copyright © 2018 Elsevier B.V. All rights reserved.

Supercritical fluid extraction of grape seeds: extract chemical composition, antioxidant activity and inhibition of nitrite production in LPS-stimulated Raw 264.7 cells.

PubMed

Pérez, Concepción; Ruiz del Castillo, María Luisa; Gil, Carmen; Blanch, Gracia Patricia; Flores, Gema

2015-08-01

Grape by-products are a rich source of bioactive compounds having broad medicinal properties, but are usually wasted from juice/wine processing industries. The present study investigates the use of supercritical fluid extraction (SFE) for obtaining an extract rich in bioactive compounds. First, some variables involved in the extraction were applied. SFE conditions were selected based on the oil mass yield, fatty acid profile and total phenolic composition. As a result, 40 °C and 300 bar were selected as operational conditions. The phenolic composition of the grape seed oil was determined using LC-DAD. The antioxidant activity was determined by ABTS and DPPH assays. For the anti-inflammatory activity the inhibition of nitrite production was assessed. The grape seed oil extracted was rich in phenolic compounds and fatty acids with significant antioxidant and anti-inflammatory activities. From these results, added economic value to this agroindustrial residue is proposed using environmentally friendly techniques.

Development of a selective and pH-independent method for the analysis of ultra trace amounts of nitrite in environmental water samples after dispersive magnetic solid phase extraction by spectrofluorimetry.

PubMed

Daneshvar Tarigh, Ghazale; Shemirani, Farzaneh

2014-10-01

This paper describes an innovative and rapidly dispersive magnetic solid phase extraction spectrofluorimetry (DMSPE-FL) method for the analysis of trace amounts of nitrite in some environmental water samples. The method includes derivatization of aqueous nitrite with 2, 3-diaminonaphthalene (DAN), analysis of highly fluorescent 2, 3-naphthotriazole (NAT) derivative using spectrofluorimetry after DSPME. The novelty of our method is based on forming NAT that was independent with the pH-responsive and was adsorbed on MMWCNT by hydrophobic attractions in both acidic and basic media. The extraction efficiency of the sorbent was investigated by extraction of nitrite. The optimum extraction conditions for NO2(-) were obtained as of extraction time, 1.5 min; 10mg sorbent from 160 mL of the sample solution, and elution with 1 mL of acetone/KOH. Under the optimal conditions, the calibration curves were obtained in the range of 0.1-80 µg L(-1) (R(2)=0.999) and LOD (S/N=3) was obtained in 34 ng L(-1). Relative standard deviations (RSD) were 0.6 % (five replicates at 5 μg L(-1)). In addition, the feasibility of the method was demonstrated with extraction and determination of nitrite from some real samples containing tap, mineral, sea, rain, snow and ground waters, with the recovery in standard addition to real matrix of 94-102 % and RSDs of 1.8-10.6%. Copyright © 2014 Elsevier B.V. All rights reserved.

A Two-Component Monooxygenase Catalyzes Both the Hydroxylation of p-Nitrophenol and the Oxidative Release of Nitrite from 4-Nitrocatechol in Bacillus sphaericus JS905

PubMed Central

Kadiyala, Venkateswarlu; Spain, Jim C.

1998-01-01

Bacteria that metabolize p-nitrophenol (PNP) oxidize the substrate to 3-ketoadipic acid via either hydroquinone or 1,2,4-trihydroxybenzene (THB); however, initial steps in the pathway for PNP biodegradation via THB are unclear. The product of initial hydroxylation of PNP could be either 4-nitrocatechol or 4-nitroresorcinol. Here we describe the complete pathway for aerobic PNP degradation by Bacillus sphaericus JS905 that was isolated by selective enrichment from an agricultural soil in India. Washed cells of PNP-grown JS905 released nitrite in stoichiometric amounts from PNP and 4-nitrocatechol. Experiments with extracts obtained from PNP-grown cells revealed that the initial reaction is a hydroxylation of PNP to yield 4-nitrocatechol. 4-Nitrocatechol is subsequently oxidized to THB with the concomitant removal of the nitro group as nitrite. The enzyme that catalyzed the two sequential monooxygenations of PNP was partially purified and separated into two components by anion-exchange chromatography and size exclusion chromatography. Both components were required for NADH-dependent oxidative release of nitrite from PNP or 4-nitrocatechol. One of the components was identified as a reductase based on its ability to catalyze the NAD(P)H-dependent reduction of 2,6-dichlorophenolindophenol and nitroblue tetrazolium. Nitrite release from either PNP or 4-nitrocatechol was inhibited by the flavoprotein inhibitor methimazole. Our results indicate that the two monooxygenations of PNP to THB are catalyzed by a single two-component enzyme system comprising a flavoprotein reductase and an oxygenase. PMID:9647818

Performance evaluation of household water treatment systems used in Kerman for removal of cations and anions from drinking water

NASA Astrophysics Data System (ADS)

Malakootian, Mohammad; Amirmahani, Najmeh; Yazdanpanah, Ghazal; Nasiri, Alireza; Asadipour, Ali; Ebrahimi, Ahmad; Darvish Moghaddam, Sodaif

2017-12-01

Increased awareness in society of the consequences of contaminants in drinking water has created a demand for household water treatment systems, which provide higher quality water, to spread. The aim of this study was to evaluate the performance of household water treatment systems used in Kerman for the removal of cations and anions. Various brands of home water treatment devices commonly used in Kerman were selected, with one device chosen from each brand for study. In cases in which the devices were used extensively, samples were selected with filters that had been changed in proper time, based on the device's operational instructions. The samples were selected from homes in the center and four geographical directions of Kerman. Then, sampling was conducted in three stages of input and output water of each device. For each of the samples, parameters were measured, such as chloride, sulfate, bicarbonate, calcium, magnesium, hardness, sodium, nitrate and nitrite (mg/L), temperature (°C), and pH. The average removal efficiency of different parameters by 14 brands in Kerman, which include chloride ions, sulfate, bicarbonate, calcium, magnesium, sodium, nitrites, nitrates, and total hardness, was obtained at 68.48, 85, 67, 61.21, 78.97, 80.24, 32.59, 66.83, and 69.38%, respectively. The amount of sulfate, bicarbonate, chloride, calcium, magnesium, hardness, sodium, and nitrate in the output water of household water treatment systems was less than the input water of these devices, but nitrite concentration in the output of some devices was more than the input water and showed a significant difference ( p > 0.05).

[Detection of nitrite and nitrosocompounds in chemical systems and biological liquids by the calorimetric method].

PubMed

Titov, V Iu; Petrenko, Iu M; Vanin, A F; Stepuro, I I

2010-01-01

The capacity of nitrite, S-nitrosothiols (RS-NO), dinitrosyl iron complexes (DNICs) with thiol-containing ligands, and nitrosoamines to inhibit catalase has been used for the selective determination of these compounds in purely chemical systems and biological liquids: cow milk and colostram. The limiting sensitivity of the method is 50 nM. A comparison of the results of the determinations of RS-NO, DNIC, and nitrite by the catalase method and the Greese method conventionally used for nitrite detection showed that, firstly, Greese reagents decompose DNIC and RS-NO to form nitrite. Therefore, the Greese method cannot be used for nitrite determination in solutions of these substances. Secondly, Greese reagents interact with complexes of mercury ions with RS-NO, inducing the release of nitrosonium ions from the complex followed by the hydrolysis of nitrosonium to nitrite. Thus, the proposition about the spontaneous decay of the complexes of mercury ions with RS-NO is incorrect. Keeping in mind a high sensitivity of the method, the use of catalase as an enzyme detector of nitrosocompounds allows one to detect these compounds in neutral medium without prior purification of the object, thereby preventing artificial effects due to noncontrolled modifications of the compounds under study.

Enhanced XOR activity in eNOS-deficient mice: Effects on the nitrate-nitrite-NO pathway and ROS homeostasis.

PubMed

Peleli, Maria; Zollbrecht, Christa; Montenegro, Marcelo F; Hezel, Michael; Zhong, Jianghong; Persson, Erik G; Holmdahl, Rikard; Weitzberg, Eddie; Lundberg, Jon O; Carlström, Mattias

2016-10-01

Xanthine oxidoreductase (XOR) is generally known as the final enzyme in purine metabolism and as a source of reactive oxygen species (ROS). In addition, this enzyme has been suggested to mediate nitric oxide (NO) formation via reduction of inorganic nitrate and nitrite. This NO synthase (NOS)-independent pathway for NO generation is of particular importance during certain conditions when NO bioavailability is diminished due to reduced activity of endothelial NOS (eNOS) or increased oxidative stress, including aging and cardiovascular disease. The exact interplay between NOS- and XOR-derived NO generation is not fully elucidated yet. The aim of the present study was to investigate if eNOS deficiency is associated with changes in XOR expression and activity and the possible impact on nitrite, NO and ROS homeostasis. Plasma levels of nitrate and nitrite were similar between eNOS deficient (eNOS -/- ) and wildtype (wt) mice. XOR activity was upregulated in eNOS -/- compared with wt, but not in nNOS -/- , iNOS -/- or wt mice treated with the non-selective NOS inhibitor L-NAME. Following an acute dose of nitrate, plasma nitrite increased more in eNOS -/- compared with wt, and this augmented response was abolished by the selective XOR inhibitor febuxostat. Livers from eNOS -/- displayed higher nitrite reducing capacity compared with wt, and this effect was attenuated by febuxostat. Dietary supplementation with nitrate increased XOR expression and activity, but concomitantly reduced superoxide generation. The latter effect was also seen in vitro after nitrite administration. Treatment with febuxostat elevated blood pressure in eNOS -/- , but not in wt mice. A high dose of dietary nitrate reduced blood pressure in naïve eNOS -/- mice, and again this effect was abolished by febuxostat. In conclusion, eNOS deficiency is associated with an upregulation of XOR facilitating the nitrate-nitrite-NO pathway and decreasing the generation of ROS. This interplay between XOR and eNOS is proposed to play a significant role in NO homeostasis and blood pressure regulation. Copyright © 2016 Elsevier Inc. All rights reserved.

Nitrite sensing composite systems based on a core-shell emissive-superamagnetic structure: Construction, characterization and sensing behavior

NASA Astrophysics Data System (ADS)

Yang, Yan; Liu, Liang; Zha, Jianhua; Yuan, Ningyi

2017-04-01

Two recyclable nitrite sensing composite samples were designed and constructed through a core-shell structure, with Fe3O4 nanoparticles as core, silica molecular sieve MCM-41 as shell and two rhodamine derivatives as chemosensors, respectively. These samples and their structure were identified with their electron microscopy images, N2 adsorption/desorption isotherms, magnetic response, IR spectra and thermogravimetric analysis. Their nitrite sensing behavior was discussed based on emission intensity quenching, their limit of detection was found as low as 1.2 μM. Further analysis suggested a static sensing mechanism between nitrite and chemosensors through an additive reaction between NO+ and chemosensors. After finishing their nitrite sensing, these composite samples and their emission could be recycled and recovered by sulphamic acid.

Meat processing and colon carcinogenesis: cooked, nitrite-treated, and oxidized high-heme cured meat promotes mucin-depleted foci in rats

PubMed Central

Santarelli, Raphaëlle L; Vendeuvre, Jean-Luc; Naud, Nathalie; Taché, Sylviane; Guéraud, Françoise; Viau, Michelle; Genot, Claude; Corpet, Denis E; Pierre, Fabrice H F

2010-01-01

Processed meat intake is associated with colorectal cancer risk, but no experimental study supports the epidemiologic evidence. To study the effect of meat processing on carcinogenesis promotion, we first did a 14-day study with 16 models of cured meat. Studied factors, in a 2 × 2 × 2 × 2 design, were muscle color (a proxy for heme level), processing temperature, added nitrite, and packaging. Fischer 344 rats were fed these 16 diets, and we evaluated fecal and urinary fat oxidation and cytotoxicity, three biomarkers of heme-induced carcinogenesis promotion. A principal component analysis allowed for selection of four cured meats for inclusion into a promotion study. These selected diets were given for 100 days to rats pretreated with 1,2-dimethylhydrazine. Colons were scored for preneoplastic lesions: aberrant crypt foci (ACF) and mucin-depleted foci (MDF). Cured meat diets significantly increased the number of ACF/colon compared with a no-meat control diet (P = 0.002). Only the cooked nitrite-treated and oxidized high heme meat significantly increased the fecal level of apparent total N-nitroso compounds (ATNC) and the number of MDF per colon compared with the no-meat control diet (P < 0.05). This nitrite-treated and oxidized cured meat specifically increased the MDF number compared with similar non nitrite-treated meat (P = 0.03) and with similar non oxidized meat (P = 0.004). Thus, a model cured meat, similar to ham stored aerobically, increased the number of preneoplastic lesions, which suggests colon carcinogenesis promotion. Nitrite treatment and oxidation increased this promoting effect, which was linked with increased fecal ATNC level. This study could lead to process modifications to make non promoting processed meat. PMID:20530708

Investigation of reduction and tolerance capability of lactic acid bacteria isolated from kimchi against nitrate and nitrite in fermented sausage condition.

PubMed

Paik, Hyun-Dong; Lee, Joo-Yeon

2014-08-01

Lactobacillus brevis KGR3111, Lactobacillus curvatus KGR 2103, Lactobacillus plantarum KGR 5105, and Lactobacillus sakei KGR 4108 isolated from kimchi were investigated for their potential to be used as starter culture for fermented sausages with the capability to reduce and tolerate nitrate/nitrite. The reduction capability of tested strains for nitrate was not dramatic. All tested strains, however, showed the capability to produce nitrite reductase with the reduction amount of 58.46-75.80 mg/l of NO(2)(-). L. brevis and L. plantarum showed nitrate tolerance with the highest number of 8.71 log cfu/ml and 8.81 log cfu/ml, and L. brevis and L. sakei exhibited nitrite tolerance with the highest number of 8.24 log cfu/ml and 8.25 log cfu/ml, respectively. As a result, L. brevis, L. plantarum, and L. sakei isolated from kimchi showed a tolerance against nitrate or nitrite with a good nitrite reduction capability, indicating the satisfaction of one of the selection criteria to be used as starter culture for fermented sausages. Copyright © 2014 Elsevier Ltd. All rights reserved.

FIA-Spectrophotometric Method for Determination of Nitrite in Meat Products: An Experiment Exploring Color Reduction of an Azo-Compound

ERIC Educational Resources Information Center

Penteado, Jose C.; Angnes, Lucio; Masini, Jorge C.; Oliveira, Paulo C. C.

2005-01-01

This article describes the reaction between nitrite and safranine O. This sensitive reaction is based on the disappearance of color of the reddish-orange azo dye, allowing the determination of nitrite at the mg mL-1 level. A factorial optimization of parameters was carried out and the method was applied for the quantification of nitrite in…

Nitrate decreases xanthine oxidoreductase-mediated nitrite reductase activity and attenuates vascular and blood pressure responses to nitrite.

PubMed

Damacena-Angelis, Célio; Oliveira-Paula, Gustavo H; Pinheiro, Lucas C; Crevelin, Eduardo J; Portella, Rafael L; Moraes, Luiz Alberto B; Tanus-Santos, Jose E

2017-08-01

Nitrite and nitrate restore deficient endogenous nitric oxide (NO) production as they are converted back to NO, and therefore complement the classic enzymatic NO synthesis. Circulating nitrate and nitrite must cross membrane barriers to produce their effects and increased nitrate concentrations may attenuate the nitrite influx into cells, decreasing NO generation from nitrite. Moreover, xanthine oxidoreductase (XOR) mediates NO formation from nitrite and nitrate. However, no study has examined whether nitrate attenuates XOR-mediated NO generation from nitrite. We hypothesized that nitrate attenuates the vascular and blood pressure responses to nitrite either by interfering with nitrite influx into vascular tissue, or by competing with nitrite for XOR, thus inhibiting XOR-mediated NO generation. We used two independent vascular function assays in rats (aortic ring preparations and isolated mesenteric arterial bed perfusion) to examine the effects of sodium nitrate on the concentration-dependent responses to sodium nitrite. Both assays showed that nitrate attenuated the vascular responses to nitrite. Conversely, the aortic responses to the NO donor DETANONOate were not affected by sodium nitrate. Further confirming these results, we found that nitrate attenuated the acute blood pressure lowering effects of increasing doses of nitrite infused intravenously in freely moving rats. The possibility that nitrate could compete with nitrite and decrease nitrite influx into cells was tested by measuring the accumulation of nitrogen-15-labeled nitrite ( 15 N-nitrite) by aortic rings using ultra-performance liquid chromatography tandem mass-spectrometry (UPLC-MS/MS). Nitrate exerted no effect on aortic accumulation of 15 N-nitrite. Next, we used chemiluminescence-based NO detection to examine whether nitrate attenuates XOR-mediated nitrite reductase activity. Nitrate significantly shifted the Michaelis Menten saturation curve to the right, with a 3-fold increase in the Michaelis constant. Together, our results show that nitrate inhibits XOR-mediated NO production from nitrite, and this mechanism may explain how nitrate attenuates the vascular and blood pressure responses to nitrite. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Determination of selected anions in water by ion chromatography

USGS Publications Warehouse

Fishman, Marvin J.; Pyen, Grace

1979-01-01

Ion chromatography is a rapid, sensitive, precise, and accurate method for the determination of major anions in rain water and surface waters. Simultaneous analyses of a single sample for bromide, chloride, fluoride, nitrate, nitrite, orthophosphate, and sulfate require approximately 20 minutes to obtain a chromatogram.Minimum detection limits range from 0.01 milligrams per liter for fluoride to 0.20 milligrams per liter for chloride and sulfate. Percent relative standard deviations were less than nine percent for all anions except nitrite in Standard Reference Water Samples. Only one reference sample contained nitrite and its concentration was near the minimum level of detection. Similar precision was found for chloride, nitrate, and sulfate at concentrations less than 5 milligrams per liter in rainfall samples. Precision for fluoride ranged from 12 to 22 percent, but is attributed to the low concentrations in these samples. The other anions were not detected.To determine accuracy of results, several samples were spiked with known concentrations of fluoride, chloride, nitrate, and sulfate; recoveries ranged from 96 to 103 percent. Known amounts of bromide and phosphate were added, separately, to several other waters, which contained bromide or phosphate. Recovery of added bromide and phosphate ranged from approximately 95 to 104 percent. No recovery data were obtained for nitrite.Chloride, nitrate, nitrite, orthophosphate, and sulfate, in several samples, were also determined independently by automated colorimetric procedures. An automated ion-selective electrode method was used to determine fluoride. Results are in agreement with results obtained by ion chromatography.

Quantification of residual nitrite and nitrate in ham by reverse-phase high performance liquid chromatography/diode array detector.

PubMed

Ferreira, I M P L V O; Silva, S

2008-02-15

Nitrite and nitrate are used as additives in ham industry to provide colour, taste and protect against clostridia. The classical colorimetric methods widely used to determine nitrite and nitrate are laborious, suffer from matrix interferences and involve the use of toxic cadmium. The use of chromatography is potentially attractive since it is more rapid, sensitive, selective and provides reliable and accurate results. A rapid and cost-effective RP-HPLC method with diode array detector was optimized and validated for quantification of nitrites and nitrates in ham. The chromatographic separation was achieved using a HyPurity C18, 5 microm chromatographic column and gradient elution with 0.01 M n-octylamine and 5mM tetrabutylammonium hydrogenosulphate to pH 6.5. The determinations were performed in the linear range of 0.0125-10.0mg/L for nitrite and 0.0300-12.5 g/L for nitrate. The detection limits were 0.019 and 0.050 mg/kg, respectively. The reliability of the method in terms of precision and accuracy was evaluated. Coefficients of variation lower than 2.89% and 5.47% were obtained for nitrite and nitrate, respectively (n=6). Recoveries of residual nitrite/nitrate ranged between 93.6% and 104.3%. Analysis of cooked and dried ham samples was performed, and the results obtained were in agreement with reference procedures.

Controlling the nitrite:ammonium ratio in a SHARON reactor in view of its coupling with an Anammox process.

PubMed

Volcke, E I P; van Loosdrecht, M C M; Vanrolleghem, P A

2006-01-01

The combined SHARON-Anammox process for treating wastewater streams with high ammonia load is the focus of this paper. In particular, partial nitritation in the SHARON reactor should be performed to such an extent that a nitrite:ammonium ratio is generated which is optimal for full conversion in an Anammox process. In the simulation studies performed in this contribution, the nitrite:ammonium ratio produced in a SHARON process with fixed volume, as well as its effect on the subsequent Anammox process, is examined for realistic influent conditions and considering both direct and indirect pH effects on the SHARON process. Several possible operating modes for the SHARON reactor, differing in control strategies for O2, pH and the produced nitrite:ammonium ratio and based on regulating the air flow rate and/or acid/base addition, are systematically evaluated. The results are quantified through an operating cost index. Best results are obtained by means of cascade feedback control of the SHARON effluent nitrite:ammonium ratio through setting an O2 set-point that is tracked by adjusting the air flow rate, combined with single loop pH control through acid/base addition.

Can urinary nitrite results be used to conduct antimicrobial option for urinary tract infection in children?

PubMed

Mahyar, Abolfazl; Ayazi, Parviz; Froozesh, Mahta; Daneshi-Kohan, Mohammad-Mahdi; Barikani, Ameneh

2012-06-01

This study was performed to determine the relationship between urinary nitrite results and bacterial resistance to antimicrobial drugs in urinary tract infection of children. In a cross-section study 119 children younger than 12 years with urinary tract infection were evaluated in Qazvin children's hospital. Patients were divided into negative and positive nitrite groups depending on urinary nitrite test result. Rates of antibiotic resistance in the two groups were compared. Sixty seven patients were in the negative nitrite group and 52 in the positive nitrite group. Resistance rates to ceftriaxone, trimethoprim sulfamethoxazole, ampicillin, gentamicin, amikacin, nalidixic acid, cephalothin and nitrofurantoin in the nitrite negative group were 7.5%, 31.3%, 50.7%, 11.9%, 9%, 3%, 14.9% and 11.9%, respectively. These values in the nitrite positive group were 21.2%, 28.8%, 63.5%, 7.7%, 5.8%, 1.9%, 9.6%, and 3.8%, respectively (P>0.05). This study showed that there is no correlation between urinary nitrite results and bacterial resistance to antimicrobial drugs. Therefore, it seems that physicians should not adjust antibiotic therapy for UTI based on nitrite results.

Dietary nitrates, nitrites, and cardiovascular disease.

PubMed

Hord, Norman G

2011-12-01

Dietary nitrate (NO(3)), nitrite (NO(2)), and arginine can serve as sources for production of NO(x) (a diverse group of metabolites including nitric oxide, nitrosothiols, and nitroalkenes) via ultraviolet light exposure to skin, mammalian nitrate/nitrite reductases in tissues, and nitric oxide synthase enzymes, respectively. NO(x) are responsible for the hypotensive, antiplatelet, and cytoprotective effects of dietary nitrates and nitrites. Current regulatory limits on nitrate intakes, based on concerns regarding potential risk of carcinogenicity and methemoglobinemia, are exceeded by normal daily intakes of single foods, such as soya milk and spinach, as well as by some recommended dietary patterns such as the Dietary Approaches to Stop Hypertension diet. This review includes a call for regulatory bodies to consider all available data on the beneficial physiologic roles of nitrate and nitrite in order to derive rational bases for dietary recommendations.

Statistical, graphical, and trend summaries of selected water-quality and streamflow data from the Trinity River near Crockett, Texas, 1964-85

USGS Publications Warehouse

Goss, Richard L.

1987-01-01

As part of the statistical summaries, trend tests were conducted. Several small uptrends were detected for total nitrogen, total organic nitrogen, total ammonia nitrogen, total nitrite nitrogen, total nitrate nitrogen, total organic plus ammonia nitrogen, total nitrite plus nitrate nitrogen, and total phosphorus. Small downtrends were detected for biochemical oxygen demand and dissolved magnesium.

Rapid determination of isoamyl nitrite in pharmaceutical preparations by flow injection analysis with on-line UV irradiation and luminol chemiluminescence detection.

PubMed

Kishikawa, Naoya; Kondo, Naoko; Amponsaa-Karikari, Abena; Kodamatani, Hitoshi; Ohyama, Kaname; Nakashima, Kenichiro; Yamazaki, Shigeo; Kuroda, Naotaka

2014-02-01

Isoamyl nitrite is used as a therapeutic reagent for cardiac angina and as an antidote for cyanide poisoning, but it is abused because of its euphoric properties. Therefore, a method to determine isoamyl nitrite is required in many fields, including pharmaceutical and forensic studies. In this study, a simple, rapid and sensitive method for the determination of isoamyl nitrite was developed using a flow injection analysis system equipped with a chemiluminescence detector and on-line photoreactor. This method is based on on-line ultraviolet irradiation of isoamyl nitrite and subsequent luminol chemiluminescence detection without the addition of an oxidant. A linear standard curve was obtained up to 1.0 μM of isoamyl nitrite with a detection limit (blank + 3SD) of 0.03 μM. The method was successfully applied to determine isoamyl nitrite content in pharmaceutical preparations. Copyright © 2013 John Wiley & Sons, Ltd.

Ammonia- and nitrite-oxidizing bacterial communities in a pilot-scale chloraminated drinking water distribution system.

PubMed

Regan, John M; Harrington, Gregory W; Noguera, Daniel R

2002-01-01

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 oxidizers, 16S rDNA-targeted T-RFLP indicated the presence of Nitrosomonas in each of the distribution systems, with a considerably smaller peak attributable to Nitrosospira-like AOB. Sequences of AOB amplification products aligned within the Nitrosomonas oligotropha cluster and were closely related to N. oligotropha and Nitrosomonas ureae. The nitrite-oxidizing communities were comprised primarily of Nitrospira, although Nitrobacter was detected in some samples. These results suggest a possible selection of AOB related to N. oligotropha and N. ureae in chloraminated systems and demonstrate the presence of NOB, indicating a biological mechanism for nitrite loss that contributes to a reduction in nitrite-associated chloramine decay.

Ammonia- and Nitrite-Oxidizing Bacterial Communities in a Pilot-Scale Chloraminated Drinking Water Distribution System

PubMed Central

Regan, John M.; Harrington, Gregory W.; Noguera, Daniel R.

2002-01-01

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 oxidizers, 16S rDNA-targeted T-RFLP indicated the presence of Nitrosomonas in each of the distribution systems, with a considerably smaller peak attributable to Nitrosospira-like AOB. Sequences of AOB amplification products aligned within the Nitrosomonas oligotropha cluster and were closely related to N. oligotropha and Nitrosomonas ureae. The nitrite-oxidizing communities were comprised primarily of Nitrospira, although Nitrobacter was detected in some samples. These results suggest a possible selection of AOB related to N. oligotropha and N. ureae in chloraminated systems and demonstrate the presence of NOB, indicating a biological mechanism for nitrite loss that contributes to a reduction in nitrite-associated chloramine decay. PMID:11772611

Outcompeting nitrite-oxidizing bacteria in single-stage nitrogen removal in sewage treatment plants: a model-based study.

PubMed

Pérez, Julio; Lotti, Tommaso; Kleerebezem, Robbert; Picioreanu, Cristian; van Loosdrecht, Mark C M

2014-12-01

This model-based study investigated the mechanisms and operational window for efficient repression of nitrite oxidizing bacteria (NOB) in an autotrophic nitrogen removal process. The operation of a continuous single-stage granular sludge process was simulated for nitrogen removal from pretreated sewage at 10 °C. The effects of the residual ammonium concentration were explicitly analyzed with the model. Competition for oxygen between ammonia-oxidizing bacteria (AOB) and NOB was found to be essential for NOB repression even when the suppression of nitrite oxidation is assisted by nitrite reduction by anammox (AMX). The nitrite half-saturation coefficient of NOB and AMX proved non-sensitive for the model output. The maximum specific growth rate of AMX bacteria proved a sensitive process parameter, because higher rates would provide a competitive advantage for AMX. Copyright © 2014 Elsevier Ltd. All rights reserved.

Association of Nitrate, Nitrite, and Total Organic Carbon (TOC) in Drinking Water and Gastrointestinal Disease

PubMed Central

Khademikia, Samaneh; Rafiee, Zahra; Amin, Mohammad Mehdi; Poursafa, Parinaz; Mansourian, Marjan; Modaberi, Amir

2013-01-01

Objective. We aimed to investigate the amounts of nitrate, nitrite, and total organic carbon (TOC) in two drinking water sources and their relationship with some gastrointestinal diseases. Methods. This cross-sectional study was conducted in 2012 in Iran. Two wells located in residential areas were selected for sampling and measuring the TOC, nitrate (NO3−), and nitrite (NO2−). This water is used for drinking as well as for industrial and agricultural consumption. Nitrate and nitrite concentrations of water samples were analyzed using DR 5000 spectrophotometer. The information of patients was collected from the records of the main referral hospital of the region for gastrointestinal diseases. Results. In both areas under study, the mean water nitrate and nitrite concentrations were higher in July than in other months. The mean TOC concentrations in areas 1 and 2 were 2.29 ± 0.012 and 2.03 ± 0.309, respectively. Pollutant concentration and gastrointestinal disease did not show any significant relationship (P > 0.05). Conclusion. Although we did not document significant association of nitrite, nitrate, and TOC content of water with gastrointestinal diseases, it should be considered that such health hazards may develop over time, and the quality of water content should be controlled to prevent different diseases. PMID:23690803

Association of nitrate, nitrite, and total organic carbon (TOC) in drinking water and gastrointestinal disease.

PubMed

Khademikia, Samaneh; Rafiee, Zahra; Amin, Mohammad Mehdi; Poursafa, Parinaz; Mansourian, Marjan; Modaberi, Amir

2013-01-01

We aimed to investigate the amounts of nitrate, nitrite, and total organic carbon (TOC) in two drinking water sources and their relationship with some gastrointestinal diseases. This cross-sectional study was conducted in 2012 in Iran. Two wells located in residential areas were selected for sampling and measuring the TOC, nitrate (NO3(-)), and nitrite (NO2(-)). This water is used for drinking as well as for industrial and agricultural consumption. Nitrate and nitrite concentrations of water samples were analyzed using DR 5000 spectrophotometer. The information of patients was collected from the records of the main referral hospital of the region for gastrointestinal diseases. In both areas under study, the mean water nitrate and nitrite concentrations were higher in July than in other months. The mean TOC concentrations in areas 1 and 2 were 2.29 ± 0.012 and 2.03 ± 0.309, respectively. Pollutant concentration and gastrointestinal disease did not show any significant relationship (P > 0.05). Although we did not document significant association of nitrite, nitrate, and TOC content of water with gastrointestinal diseases, it should be considered that such health hazards may develop over time, and the quality of water content should be controlled to prevent different diseases.

The nitrite-oxidizing community in activated sludge from a municipal wastewater treatment plant determined by fatty acid methyl ester-stable isotope probing.

PubMed

Kruse, Myriam; Zumbrägel, Sabine; Bakker, Evert; Spieck, Eva; Eggers, Till; Lipski, André

2013-10-01

Metabolically-active autotrophic nitrite oxidizers from activated sludge were labeled with (13)C-bicarbonate under exposure to different temperatures and nitrite concentrations. The labeled samples were characterized by FAME-SIP (fatty acid methyl ester-stable isotope probing). The compound cis-11-palmitoleic acid, which is the major lipid of the most abundant nitrite oxidizer in activated sludge, Candidatus Nitrospira defluvii, showed (13)C-incorporation in all samples exposed to 3 mM nitrite. Subsequently, the lipid cis-7-palmitoleic acid was labeled, and it indicated the activity of a nitrite oxidizer that was different from the known Nitrospira taxa in activated sludge. The highest incorporation of cis-7-palmitoleic acid label was found after incubation with a nitrite concentration of 0.3 mM at 17 and 22°C. While activity of Nitrobacter populations could not be detected by the FAME-SIP approach, an unknown nitrite oxidizer with the major lipid cis-9 isomer of palmitoleic acid exhibited (13)C-incorporation at 28°C with 30 mM nitrite. These results indicated flexibility of nitrite-oxidizing guilds in a complex community responding to different conditions. Labeled lipids so far not described for activated sludge-associated nitrifiers indicated the presence of unknown nitrite oxidizers in this habitat. The FAME-SIP-based information can be used to define appropriate conditions for the enrichment of nitrite-oxidizing guilds from complex samples. Copyright © 2013 Elsevier GmbH. All rights reserved.

Development of a Novel Process Integrating the Treatment of Sludge Reject Water and the Production of Polyhydroxyalkanoates (PHAs).

PubMed

Frison, Nicola; Katsou, Evina; Malamis, Simos; Oehmen, Adrian; Fatone, Francesco

2015-09-15

Polyhydroxyalkanoates (PHAs) from activated sludge and renewable organic material can become an alternative product to traditional plastics since they are biodegradable and are produced from renewable sources. In this work, the selection of PHA storing bacteria was integrated with the side stream treatment of nitrogen removal via nitrite from sewage sludge reject water. A novel process was developed and applied where the alternation of aerobic-feast and anoxic-famine conditions accomplished the selection of PHA storing biomass and nitrogen removal via nitrite. Two configurations were examined: in configuration 1 the ammonium conversion to nitrite occurred in the same reactor in which the PHA selection process occurred, while in configuration 2 two separate reactors were used. The results showed that the selection of PHA storing biomass was successful in both configurations, while the nitrogen removal efficiency was much higher (almost 90%) in configuration 2. The PHA selection degree was evaluated by the volatile fatty acid (VFA) uptake rate (-qVFAs) and the PHA production rate (qPHA), which were 239 ± 74 and 89 ± 7 mg of COD per gram of active biomass (Xa) per hour, respectively. The characterization of the biopolymer recovered after the accumulation step, showed that it was composed of 3-hydroxybutyrate (3HB) (60%) and 3-hydroxyvalerate (3HV) (40%). The properties associated with the produced PHA suggest that they are suitable for thermoplastic processing.

Colour formation in fermented sausages by meat-associated staphylococci with different nitrite- and nitrate-reductase activities.

PubMed

Gøtterup, Jacob; Olsen, Karsten; Knøchel, Susanne; Tjener, Karsten; Stahnke, Louise H; Møller, Jens K S

2008-04-01

Three Staphylococcus strains, S. carnosus, S. simulans and S. saprophyticus, selected due to their varying nitrite and/or nitrate-reductase activities, were used to initiate colour formation during sausage fermentation. During fermentation of sausages with either nitrite or nitrate added, colour was followed by L(∗)a(∗)b measurements and the content of nitrosylmyoglobin (MbFe(II)NO) quantified by electron spin resonance (ESR). MbFe(II)NO was rapidly formed in sausages with added nitrite independent of the presence of nitrite reducing bacteria, whereas the rate of MbFe(II)NO formation in sausages with added nitrate depended on the specific Staphylococcus strain. Strains with high nitrate-reductase activity showed a significantly faster rate of pigment formation, but other factors were of influence as well. Product stability for the sliced, packaged sausage was evaluated as surface colour and oxidation by autofluorescence and hexanal content, respectively. No significant direct effect of the Staphylococcus addition was observed, however, there was a clear correspondence between high initial amount of MbFe(II)NO in the different sausages and the colour stability during storage. Autofluorescence data correlated well with hexanal content, and may be used as predictive tools. Overall, nitrite- and nitrate-reductase activities of Staphylococcus strains in nitrite-cured sausages were of limited importance regarding colour development, while in nitrate-cured sausages strains with higher nitrate reductase activity were crucial for ensuring optimal colour formation during initial fermentation stages.

Effect of leek and onion on processing and quality characteristics of Greek traditional sausages.

PubMed

Fista, G A; Bloukas, J G; Siomos, A S

2004-10-01

The objective of this study was to investigate the effect of leek and onion on processing and quality characteristics of sausages and select the most appropriate, to determine the optimum level of selected vegetable and to improve its effectiveness on quality characteristics of sausages, in comparison to the addition of nitrites (100 ppm), by using a starter culture of Staphylococcus carnosus and ascorbate. The nitrate content of leek ranged from 213 to 255 ppm and that of onion was 79 ppm. Sausages produced with leek had higher (p<0.05) nitrite content (1.3-2.1 ppm) and a (∗)(+) values and higher scores for sensory attributes than sausages with onion. Sausages made with the total leek plant had the highest score for overall acceptability. The higher the leek level the higher the nitrate and nitrite content of sausages and the lower the redness, a (∗)(+). Sausages with 240 g of leek/kg had the highest (p<0.05) overall acceptability. Sausages with higher leek level had an intensive wrinkling on the surface and also an intensive and undesirable green colour. Sausages produced with 240 g of leek/kg had the same low level of nitrate and nitrite content, higher weight losses and lower pH values after the 3rd day of storage, compared to sausages produced with the addition of sodium nitrite. The addition of starter culture and ascorbic acid improved the redness (a (∗)) of sausages and reduced the 2-thiobarbituric acid value. Sausages with leek, starter culture and ascorbic acid had the highest score for odour and taste and overall acceptability.

Nitrogen polishing in a fully anoxic anammox MBBR treating mainstream nitritation-denitritation effluent.

PubMed

Regmi, Pusker; Holgate, Becky; Miller, Mark W; Park, Hongkeun; Chandran, Kartik; Wett, Bernhard; Murthy, Sudhir; Bott, Charles B

2016-03-01

As nitrogen discharge limits are becoming more stringent, short-cut nitrogen systems and tertiary nitrogen polishing steps are gaining popularity. For partial nitritation or nitritation-denitritation systems, anaerobic ammonia oxidation (anammox) polishing may be feasible to remove residual ammonia and nitrite from the effluent. Nitrogen polishing of mainstream nitritation-denitritation system effluent via anammox was studied at 25°C in a fully anoxic moving bed bioreactor (MBBR) (V = 0.45 m(3) ) over 385 days. Unlike other anammox based processes, a very fast startup of anammox MBBR was demonstrated, despite nitrite limited feeding conditions (influent nitrite = 0.7 ± 0.59 mgN/L, ammonia = 6.13 ± 2.86 mgN/L, nitrate = 3.41 ± 1.92 mgN/L). The nitrogen removal performance was very stable within a wide range of nitrogen inputs. Anammox bacteria (AMX) activity up to 1 gN/m(2) /d was observed which is comparable to other biofilm-based systems. It is generally believed that nitrate production limits nitrogen removal through AMX metabolism. However, in this study, anammox MBBR demonstrated ammonia, nitrite, and nitrate removal at limited chemical oxygen demand (COD) availability. AMX and heterotrophs contributed to 0.68 ± 0.17 and 0.32 ± 0.17 of TIN removal, respectively. It was speculated that nitrogen removal might be aided by denitratation which could be due to heterotrophs or the recently discovered ability for AMX to use short-chain fatty acids to reduce nitrate to nitrite. This study demonstrates the feasibility of anammox nitrogen polishing in an MBBR is possible for nitritation-denitration systems. © 2015 Wiley Periodicals, Inc.

Effect of pH and nitrite concentration on nitrite oxidation rate.

PubMed

Jiménez, E; Giménez, J B; Ruano, M V; Ferrer, J; Serralta, J

2011-10-01

The effect of pH and nitrite concentration on the activity of the nitrite oxidizing bacteria (NOB) in an activated sludge reactor has been determined by means of laboratory batch experiments based on respirometric techniques. The bacterial activity was measured at different pH and at different total nitrite concentrations (TNO₂). The experimental results showed that the nitrite oxidation rate (NOR) depends on the TNO₂ concentration independently of the free nitrous acid (FNA) concentration, so FNA cannot be considered as the real substrate for NOB. NOB were strongly affected by low pH values (no activity was detected at pH 6.5) but no inhibition was observed at high pH values (activity was nearly the same for the pH range 7.5-9.95). A kinetic expression for nitrite oxidation process including switch functions to model the effect of TNO₂ concentration and pH inhibition is proposed. Substrate half saturation constant and pH inhibition constants have been obtained. Copyright © 2011 Elsevier Ltd. All rights reserved.

Effects of high hydrostatic pressure and varying concentrations of sodium nitrite from traditional and vegetable-based sources on the growth of Listeria monocytogenes on ready-to-eat (RTE) sliced ham.

PubMed

Myers, Kevin; Cannon, Jerry; Montoya, Damian; Dickson, James; Lonergan, Steven; Sebranek, Joseph

2013-05-01

The objective of this study was to determine the effect the source of added nitrite and high hydrostatic pressure (HHP) had on the growth of Listeria monocytogenes on ready-to-eat (RTE) sliced ham. Use of 600MPa HHP for 3min resulted in an immediate 3.9-4.3log CFU/g reduction in L. monocytogenes numbers, while use of 400MPa HHP (3min) provided less than 1log CFU/g reduction. With the 600MPa HHP treatment, sliced ham with a conventional concentration of sodium nitrite (200ppm) was not different in L. monocytogenes growth from use with 50 or 100ppm of sodium nitrite in pre-converted celery powder. Instrumental color values as well as residual nitrite and residual nitrate concentrations for cured (sodium nitrite and nitrite from celery powder) and uncured ham formulations are discussed. Copyright © 2013 Elsevier Ltd. All rights reserved.

Green Alternatives to Nitrates and Nitrites in Meat-based Products-A Review.

PubMed

Gassara, Fatma; Kouassi, Anne Patricia; Brar, Satinder Kaur; Belkacemi, Khaled

2016-10-02

Several food additives are added in food for their preservation to maintain the freshness of food (antioxidants) or to slow down or stop the growth of microorganisms (preservative agents). Nitrites and nitrates are used as preservative agents in meat. Nitrites give a smoked taste, a pinkish color in the meat and protect the consumers against the risk of bacterial deterioration. Their addition is however very limited as, in high dose, it can have risks on human health and the environment. Nitrites may also combine with secondary or tertiary amines to form N-nitroso derivatives. Certain N-nitroso compounds have been shown to produce cancers in a wide range of laboratory animals. Thus, alternatives of nitrates and nitrites are the object of numerous research studies. Alternatives, such as the addition of vitamins, fruits, chemicals products, natural products containing nitrite or spices, which have similar properties of nitrites, are in evaluation. In fact, spices are considered to have several organoleptic and anti-microbial properties which would be interesting to study. Several spices and combinations of spices are being progressively evaluated. This review discusses the sources of nitrites and nitrates, their use as additives in food products, their physicochemical properties, their negatives effects and the use of alternatives of nitrites and nitrates in preserving meat products.

Isolation, characterization and strain selection of a Paenibacillus species for use as a probiotic to aid in ruminal methane mitigation, nitrate/nitrite detoxification and food safety.

PubMed

Latham, Elizabeth A; Pinchak, William E; Trachsel, Julian; Allen, Heather K; Callaway, Todd R; Nisbet, David J; Anderson, Robin C

2018-04-30

The effects of dietary nitrate and Paenibacillus 79R4 (79R4), a denitrifying bacterium, when co-administered as a probiotic, on methane emissions, nitrate and nitrite-metabolizing capacity and fermentation characteristics were studied in vitro. Mixed populations of rumen microbes inoculated with 79R4 metabolized all levels of nitrite studied after 24 h in vitro incubation. Results from in vitro simulations resulted in up to 2 log 10 colony forming unit reductions in E. coli O157:H7 and Campylobacter jejuni when these were co-cultured with 79R4. Nitrogen gas was the predominant final product of nitrite reduction by 79R4. When tested with nitrate-treated incubations of rumen microbes, 79R4 inoculation (provided to achieve 10 6  cells/mL rumen fluid volume) complemented the ruminal methane-decreasing potential of nitrate (P < 0.05) while concurrently increasing fermentation efficiency and enhancing ruminal nitrate and nitrite-metabolizing activity (P < 0.05) compared to untreated and nitrate only-treated incubations. Copyright © 2018 Elsevier Ltd. All rights reserved.

Shortcut nitrification/partial nitritation start-up for reject water treatment in a SBR

NASA Astrophysics Data System (ADS)

Muszyński-Huhajło, Mateusz; Miodoński, Stanisław

2017-11-01

For many wastewater treatment plants (WWTPs), side-stream treatment of reject water from digested sludge dewatering is a feasible opportunity to improve N-removal efficiency without costly plant expansion. Biological nitrogen removal over nitrite or combined partial nitritation (PN)-Anammox process has recently become a popular treatment method for such ammonium-rich streams. Shortcut nitrification and PN start-ups were successfully performed in a pilot-scale SBR treating real reject water. In all performed experiments, effective nitrate production inhibition occurred in less than 20 days due to operational conditions selection and without advanced control system. pH adjustment in the PN reactor allowed to achieve NO2-N /NH4-N ratio suitable for Anammox process (1.24±0.07).

The presence of urinary nitrites is a significant predictor of pediatric urinary tract infection susceptibility to first- and third-generation cephalosporins.

PubMed

Weisz, Dany; Seabrook, Jamie A; Lim, Rodrick K

2010-07-01

Previous studies in adults have refuted the use of nitrites as a predictor of bacterial resistance to both trimethoprim-sulfamethoxazole and cephalosporins. Some centers now consider first-line outpatient therapy with an oral third-generation cephalosporin appropriate for young children. The objective of this study was to determine if nitrite-negative pediatric urinary tract infections (UTIs) were more likely than nitrite-positive UTIs to be resistant to cephalosporins. This may enable physicians to adjust antimicrobial therapy before patients leave the Emergency Department (ED) to avoid the complications of ineffectively treated pediatric UTIs. A retrospective chart review examined, over a 9-month period, 173 pediatric patients who were diagnosed with a clinical UTI in the ED and who also had a positive urine culture and a recorded dipstick at the time of visit. The chi-squared test and Fisher's exact test were used to compare nitrite-negative vs. nitrite-positive UTIs for resistance to third-generation cephalosporins and other empiric antimicrobials. For third-generation cephalosporins, 1.4% of nitrite-positive UTIs were resistant, whereas 14.4% of nitrite-negative UTIs were resistant (95% confidence interval [CI] -0.22 to -0.05). For first-generation cephalosporins, 8.4% were resistant in the nitrite-positive group, compared to 22.2% in the nitrite-negative group (95% CI -0.24 to -0.03). The absence of urinary nitrites is a significant indicator for potential resistance to cephalosporins in pediatric UTIs. Due to low levels of pediatric UTI resistance, cephalosporins continue to represent useful empiric therapy in the general pediatric population. However, in high-risk patients, physicians may opt to alter their empiric choice of antibiotic based on the presence of urinary nitrites. Copyright 2010 Elsevier Inc. All rights reserved.

Role of nitrite in the photochemical formation of radicals in the snow.

PubMed

Jacobi, Hans-Werner; Kleffmann, Jörg; Villena, Guillermo; Wiesen, Peter; King, Martin; France, James; Anastasio, Cort; Staebler, Ralf

2014-01-01

Photochemical reactions in snow can have an important impact on the composition of the atmosphere over snow-covered areas as well as on the composition of the snow itself. One of the major photochemical processes is the photolysis of nitrate leading to the formation of volatile nitrogen compounds. We report nitrite concentrations determined together with nitrate and hydrogen peroxide in surface snow collected at the coastal site of Barrow, Alaska. The results demonstrate that nitrite likely plays a significant role as a precursor for reactive hydroxyl radicals as well as volatile nitrogen oxides in the snow. Pollution events leading to high concentrations of nitrous acid in the atmosphere contributed to an observed increase in nitrite in the surface snow layer during nighttime. Observed daytime nitrite concentrations are much higher than values predicted from steady-state concentrations based on photolysis of nitrate and nitrite indicating that we do not fully understand the production of nitrite and nitrous acid in snow. The discrepancy between observed and expected nitrite concentrations is probably due to a combination of factors, including an incomplete understanding of the reactive environment and chemical processes in snow, and a lack of consideration of the vertical structure of snow.

Hydrolysis and volatile fatty acids accumulation of waste activated sludge enhanced by the combined use of nitrite and alkaline pH.

PubMed

Huang, Cheng; Liu, Congcong; Sun, Xiuyun; Sun, Yinglu; Li, Rui; Li, Jiansheng; Shen, Jinyou; Han, Weiqing; Liu, Xiaodong; Wang, Lianjun

2015-12-01

Volatile fatty acids (VFAs) production from anaerobic digestion of waste activated sludge (WAS) is often limited by the slow hydrolysis and/or poor substrate availability. Increased attention has been given to enhance the hydrolysis and acidification of WAS recently. This study presented an efficient and green strategy based on the combined use of nitrite pretreatment and alkaline pH to stimulate hydrolysis and VFA accumulation from WAS. Results showed that both proteins and polysaccharides increased in the presence of nitrite, indicating the enhancement of sludge solubilization and hydrolysis processes. Mechanism investigations showed that nitrite pretreatment could disintegrate the sludge particle and disperse extracellular polymeric substances (EPS). Then, anaerobic digestion tests demonstrated VFA production increased with nitrite treatment. The maximal VFA accumulation was achieved with 0.1 g N/L nitrite dosage and pH 10.0 at a sludge retention time (SRT) of 7 days, which was much higher VFA production in comparison with the blank, sole nitrite pretreatment, or sole pH 10. The potential analysis suggested that the combined nitrite pretreatment and alkaline pH is capable of enhancing WAS digestion with a great benefit for biological nutrient removal (BNR).

Meat processing and colon carcinogenesis: cooked, nitrite-treated, and oxidized high-heme cured meat promotes mucin-depleted foci in rats.

PubMed

Santarelli, Raphaëlle L; Vendeuvre, Jean-Luc; Naud, Nathalie; Taché, Sylviane; Guéraud, Françoise; Viau, Michelle; Genot, Claude; Corpet, Denis E; Pierre, Fabrice H F

2010-07-01

Processed meat intake is associated with colorectal cancer risk, but no experimental study supports the epidemiologic evidence. To study the effect of meat processing on carcinogenesis promotion, we first did a 14-day study with 16 models of cured meat. Studied factors, in a 2 x 2 x 2 x 2 design, were muscle color (a proxy for heme level), processing temperature, added nitrite, and packaging. Fischer 344 rats were fed these 16 diets, and we evaluated fecal and urinary fat oxidation and cytotoxicity, three biomarkers of heme-induced carcinogenesis promotion. A principal component analysis allowed for selection of four cured meats for inclusion into a promotion study. These selected diets were given for 100 days to rats pretreated with 1,2-dimethylhydrazine. Colons were scored for preneoplastic lesions: aberrant crypt foci (ACF) and mucin-depleted foci (MDF). Cured meat diets significantly increased the number of ACF/colon compared with a no-meat control diet (P = 0.002). Only the cooked nitrite-treated and oxidized high-heme meat significantly increased the fecal level of apparent total N-nitroso compounds (ATNC) and the number of MDF per colon compared with the no-meat control diet (P < 0.05). This nitrite-treated and oxidized cured meat specifically increased the MDF number compared with similar nonnitrite-treated meat (P = 0.03) and with similar nonoxidized meat (P = 0.004). Thus, a model cured meat, similar to ham stored aerobically, increased the number of preneoplastic lesions, which suggests colon carcinogenesis promotion. Nitrite treatment and oxidation increased this promoting effect, which was linked with increased fecal ATNC level. This study could lead to process modifications to make nonpromoting processed meat. 2010 AACR.

Food sources of nitrates and nitrites: the physiologic context for potential health benefits.

PubMed

Hord, Norman G; Tang, Yaoping; Bryan, Nathan S

2009-07-01

The presence of nitrates and nitrites in food is associated with an increased risk of gastrointestinal cancer and, in infants, methemoglobinemia. Despite the physiologic roles for nitrate and nitrite in vascular and immune function, consideration of food sources of nitrates and nitrites as healthful dietary components has received little attention. Approximately 80% of dietary nitrates are derived from vegetable consumption; sources of nitrites include vegetables, fruit, and processed meats. Nitrites are produced endogenously through the oxidation of nitric oxide and through a reduction of nitrate by commensal bacteria in the mouth and gastrointestinal tract. As such, the dietary provision of nitrates and nitrites from vegetables and fruit may contribute to the blood pressure-lowering effects of the Dietary Approaches to Stop Hypertension (DASH) diet. We quantified nitrate and nitrite concentrations by HPLC in a convenience sample of foods. Incorporating these values into 2 hypothetical dietary patterns that emphasize high-nitrate or low-nitrate vegetable and fruit choices based on the DASH diet, we found that nitrate concentrations in these 2 patterns vary from 174 to 1222 mg. The hypothetical high-nitrate DASH diet pattern exceeds the World Health Organization's Acceptable Daily Intake for nitrate by 550% for a 60-kg adult. These data call into question the rationale for recommendations to limit nitrate and nitrite consumption from plant foods; a comprehensive reevaluation of the health effects of food sources of nitrates and nitrites is appropriate. The strength of the evidence linking the consumption of nitrate- and nitrite-containing plant foods to beneficial health effects supports the consideration of these compounds as nutrients.

Nitrite survival and nitrous oxide production of denitrifying phosphorus removal sludges in long-term nitrite/nitrate-fed sequencing batch reactors.

PubMed

Wang, Yayi; Zhou, Shuai; Ye, Liu; Wang, Hong; Stephenson, Tom; Jiang, Xuxin

2014-12-15

Nitrite-based phosphorus (P) removal could be useful for innovative biological P removal systems where energy and carbon savings are a priority. However, using nitrite for denitrification may cause nitrous oxide (N2O) accumulation and emissions. A denitrifying nitrite-fed P removal system [Formula: see text] was successfully set up in a sequencing batch reactor (SBR) and was run for 210 days. The maximum pulse addition of nitrite to [Formula: see text] was 11 mg NO2(-)-N/L in the bulk, and a total of 34 mg NO2(-)-N/L of nitrite was added over three additions. Fluorescent in situ hybridization results indicated that the P-accumulating organisms (PAOs) abundance was 75 ± 1.1% in [Formula: see text] , approximately 13.6% higher than that in a parallel P removal SBR using nitrate [Formula: see text] . Type II Accumulibacter (PAOII) (unable to use nitrate as an electron acceptor) was the main PAOs species in [Formula: see text] , contributing 72% to total PAOs. Compared with [Formula: see text] , [Formula: see text] biomass had enhanced nitrite/free nitrous acid (FNA) endurance, as demonstrated by its higher nitrite denitrification and P uptake rates. N2O accumulated temporarily in [Formula: see text] after each pulse of nitrite. Peak N2O concentrations in the bulk for [Formula: see text] were generally 6-11 times higher than that in [Formula: see text] ; these accumulations were rapidly denitrified to nitrogen gases. N2O concentration increased rapidly in nitrate-cultivated biomass when 5 or 10 mg NO2(-)-N/L per pulse was added. Whereas, N2O accumulation did not occur in nitrite-cultivated biomass until up to 30 mg NO2(-)-N/L per pulse was added. Long-term acclimation to nitrite and pulse addition of nitrite in [Formula: see text] reduced the risk of nitrite accumulation, and mitigated N2O accumulation and emissions from denitrifying P removal by nitrite. Copyright © 2014 Elsevier Ltd. All rights reserved.

Nitrate reductase activity of Staphylococcus carnosus affecting the color formation in cured raw ham.

PubMed

Bosse Née Danz, Ramona; Gibis, Monika; Schmidt, Herbert; Weiss, Jochen

2016-07-01

The influence of the nitrate reductase activity of two Staphylococcus carnosus strains used as starter cultures on the formation of nitrate, nitrite and color pigments in cured raw ham was investigated. In this context, microbiological, chemical and multivariate image analyses were carried out on cured raw hams, which were injected with different brines containing either nitrite or nitrate, with or without the S. carnosus starter cultures. During processing and storage, the viable counts of staphylococci remained constant at 6.5logcfu/g in the hams inoculated with starter cultures, while the background microbiota of the hams processed without the starter cultures developed after 14days. Those cured hams inoculated with S. carnosus LTH 7036 (high nitrate reductase activity) showed the highest decrease in nitrate and high nitrite concentrations in the end product, but were still in the range of the legal European level. The hams cured with nitrate and without starter culture or with the other strain, S. carnosus LTH 3838 (low nitrate reductase activity) showed higher residual nitrate levels and a lower nitrite content in the end product. The multivariate image analysis identified spatial and temporal differences in the meat pigment profiles of the differently cured hams. The cured hams inoculated with S. carnosus LTH 3838 showed an uncured core due to a delay in pigment formation. Therefore, the selection of starter cultures based on their nitrate reductase activity is a key point in the formation of curing compounds and color pigments in cured raw ham manufacture. Copyright © 2016 Elsevier Ltd. All rights reserved.

Evidence by chromatography and mass spectrometry that inorganic nitrite induces S-glutathionylation of hemoglobin in human red blood cells.

PubMed

Böhmer, Anke; Pich, Andreas; Schmidt, Mario; Haghikia, Arash; Tsikas, Dimitrios

2016-04-15

Previously we found by HPLC with fluorescence detection that inorganic nitrite induces oxidation of glutathione (GSH) to its disulfide (GSSG) in intact and more abundantly in lyzed red blood cells (RBCs) from healthy humans. In the present work, we performed MS-based protein analysis and observed that nitrite (range, 0-20mM) induces formation of S-glutathionyl hemoglobin (HbSSG) at cysteine (Cys) β93 and β112 of oxyhemoglobin (HbO2) in lyzed human RBCs (range, 6-8mM HbO2). Hemoglobin species were isolated from incubation mixtures of nitrite in lyzed RBCs by ultrafiltration or affinity chromatography and analyzed by HPLC and LC-MS/MS. The mechanism likely involves inhibition of catalase activity by nitrite (IC50, 9 μM), which allows H2O2 to accumulate and oxidize Cys moieties of oxyhemoglobin and erythrocytic GSH to form HbSSG in addition to GSSG. In freshly prepared hemolysate samples, nitrite induced release of superoxide and molecular oxygen. In the presence of paracetamol and nitrite in hemolysate samples, 3-nitro-paracetamol was detected. Nitrite also induced S-nitroso hemoglobin (HbSNO) formation in low yield (i.e., 0.1%). Synthetic cysteine (Cys), glutathione (GSH), N-acetylcysteine (NAC) and N-acetylcysteine ethyl ester (NACET) inhibited nitrite-induced modifications of oxyhemoglobin including methemoglobin, HbSSG (CysSH > NACET > GSH ≈ NAC; thiol concentration, 50 μM) and HbSNO. Nitrite-induced oxidative modifications may alter physiological hemoglobin functions and may require alternative treatments for conditions associated with oxidized hemoglobin like in nitrite-induced methemoglobinemia. Accumulation of soluble Cys in RBCs via oral administration of NACET could be a new promising strategy to prevent nitrite-induced methemoglobinemia by nitrite and other oxidants. Copyright © 2016 Elsevier B.V. All rights reserved.

Is dietary nitrate/nitrite exposure a risk factor for development of thyroid abnormality? A systematic review and meta-analysis.

PubMed

Bahadoran, Zahra; Mirmiran, Parvin; Ghasemi, Asghar; Kabir, Ali; Azizi, Fereidoun; Hadaegh, Farzad

2015-05-01

The potential effects of inorganic nitrate/nitrite on global health are a much debated issue. In addition to possible methemoglobinemia and carcinogenic properties, anti-thyroid effects of nitrate/nitrite have been suggested. Considering the growing significance of nitrate/nitrite and since there is no comprehensive review in data available, clarifying the effect of nitrate/nitrite on thyroid disorder outcomes is essential. Therefore, we conducted this systematic review of experimental and clinical studies, and a meta-analysis of relevant cohort and cross-sectional studies investigating the association of nitrate/nitrite exposure and thyroid function. Most animal studies show that high exposure (~10-600 times of acceptable daily intake) to nitrate/nitrite induces anti-thyroid effects, including decreased serum level of thyroid hormones and histomorphological changes in thyroid gland; however no similar observations have been documented in humans. Based on our meta-analysis, no significant association was observed between nitrate exposure and the risk of thyroid cancer, hyper- and hypothyroidism; findings from three cohort studies however showed a significant association between higher exposure to nitrite and the risk of thyroid cancer (risk = 1.48, 95% confidence interval = 1.09-2.02, P = 0.012). Additional research is needed to clarify the association between nitrate/nitrite exposures and both thyroid function and cancer. Copyright © 2015 Elsevier Inc. All rights reserved.

Enzyme-Based Ultrasensitive Electrochemical Biosensors for Rapid Assessment of Nitrite Toxicity: Recent Advances and Perspectives.

PubMed

Gahlaut, Anjum; Hooda, Vinita; Gothwal, Ashish; Hooda, Vikas

2018-05-14

In the present era of rapid international globalization and industrialization, intensive use of nitrite as a fertilizing agent in agriculture, preservative, dyeing agent, food additive and as corrosion inhibitor in industrial sectors is adversely effecting environment, natural habitats and human health. The issue of toxicity and carcinogenicity due to excessive ingestion of nitrites via the dietary intake has led to an imminent need for its efficient real-time monitoring in situ. Nitrite detection employing electrochemical biosensors has been gaining high credibility in the field of clinical research. Nitrite biosensors have emerged as an outstanding choice for portable point of care testing of nitrite quantification owing to the excellent properties, such as rapidity, miniaturization, ultra-low limits of detection, multiplexing and enhanced detection sensitivity. The article is enclosed with an interesting outlook on latest emerging trends in the development of nitrite biosensors utilizing nanomaterials, such as metal nanoparticles, carbon nanotubes, metal oxide nanoparticles, nanocomposites, polymers and biomaterials. The present review embarks on the highlights relevant to the nitrite quantification in real samples, then proceeds with a meticulous description of the most pertinent electrochemical nitrite biosensors, which have been proposed by adopting diverse materials and strategies of fabrication and finally end with the achievements and future outlook signifying the application of these nanoengineered biosensors for environmental surveillance and human safety.

Mechanisms for Cellular NO Oxidation and Nitrite Formation in Lung Epithelial Cells

PubMed Central

Zhao, Xue-Jun; Wang, Ling; Shiva, Sruti; Tejero, Jesus; Wang, Jun; Frizzell, Sam; Gladwin, Mark T.

2013-01-01

Airway lining fluid contains relatively high concentrations of nitrite and arterial blood levels of nitrite are higher than venous levels, suggesting the lung epithelium may represent an important source of nitrite in vivo. To investigate whether lung epithelial cells possess the ability to convert NO to nitrite by oxidation, and the effect of oxygen reactions on nitrite formation, the NO donor DETA NONOate was incubated with or without A549 cells or primary human bronchial epithelial (HBE) cells for 24 hrs under normoxic (21% O2) and hypoxic (1% O2) conditions. Nitrite production was significantly increased under all conditions in the presence of A549 or HBE cells, suggesting that both A549 and HBE cells have the capacity to oxidize NO to nitrite even under low oxygen conditions. The addition of oxy-hemoglobin (oxy-Hb) to the A549 cell media decreased the production of nitrite, consistent with NO scavenging limiting nitrite formation. Heat-denatured A549 cells produced much lower nitrite and bitrate, suggesting an enzymatic activity is required. This NO oxidation activity was found to be highest in membrane bound proteins with molecular sizes < 100 kDa. In addition, 1H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one] (ODQ) and cyanide inhibited formation of nitrite in A549 cells. It has been shown that ceruloplasmin (Cp) possesses an NO oxidase and nitrite synthase activity in plasma based on NO oxidation to nitrosonium cation (NO+). We observed that Cp is expressed intracellularly in lung epithelial A549 cells and secreted into medium under basal conditions and during cytokine stimulation. However, an analysis of Cp expression level and activity measured via ρ-phenylenediamine oxidase activity assay revealed very low activity compared with plasma, suggesting that there is insufficient Cp to contribute to detectable NO oxidation to nitrite in A549 cells. Additionally, Cp levels were knocked down using siRNA by more than 75% in A549 cells, with no significant change in either nitrite or cellular S-nitrosothiol (SNO) formation compared to scrambled siRNA control under basal conditions or cytokine stimulation. These data suggest that lung epithelial cells possess NO oxidase activity, which is enhanced in cell membrane associated proteins and not regulated by intracellular or secreted Cp, indicating that alternative NO oxidases determine hypoxic and normoxic nitrite formation from NO in human lung epithelial cells. PMID:23639566

Determining the N and O isotope effects of microbial nitrite reduction: the global N cycle implications of an enzyme-dependent isotope effect

NASA Astrophysics Data System (ADS)

Martin, T. S.; Casciotti, K. L.

2014-12-01

The marine nitrogen (N) cycle is a dynamic system of critical importance, since nitrogen is the limiting nutrient in over half of the world's oceans. Denitrification and anammox, the main N loss processes from the ocean, have different effects on carbon cycling and greenhouse gas emission. Understanding the balance between the two processes is vital to understanding the role of the N cycle in global climate change. One approach for investigating these processes is by using stable isotope analysis to estimate the relative magnitudes of N fluxes, particularly for biologically mediated processes. In order to make the most of the currently available isotope analysis techniques, it is necessary to know the isotope effects for each processes occurring in the environment. Nitrite reduction is an important step in denitrification. Previous work had begun to explore the N isotope effects for nitrite reduction, but no oxygen (O) isotope effect has been measured. Additionally, no consideration has been given to the type of nitrite reductase carrying out the reaction. There are two main types of respiratory nitrite reductase, one that is Cu-based and another that is Fe-based. We performed batch culture experiments with denitrifier strains possessing either a Cu-type or Fe-type nitrite reductase. Both N and O isotope effects for nitrite reduction were determined for each of these experiments by measuring the NO2- concentration, as well as the N and O isotopes of nitrite and applying a Rayleigh fractionation model. Both the N and O isotope effects were found to be significantly different between the two types of enzymes. This enzyme-linked difference in isotope effects emphasizes the importance of microbial community composition within the global N cycle.

Carbon dots based dual-emission silica nanoparticles as ratiometric fluorescent probe for nitrite determination in food samples.

PubMed

Xiang, Guoqiang; Wang, Yule; Zhang, Heng; Fan, Huanhuan; Fan, Lu; He, Lijun; Jiang, Xiuming; Zhao, Wenjie

2018-09-15

In this work, a simple and effective strategy for designing a ratiometric fluorescent nanosensor was described. A carbon dots (CDs) based dual-emission nanosensor for nitrite was prepared by coating the CDs on to dye-doped silica nanoparticles. Dual-emission silica nanoparticles fluorescence was quenched in sulfuric acid using potassium bromate (KBrO 3 ). The nitrite present catalyzed the KBrO 3 oxidation, resulting in ratiometric fluorescence response of the dual-emission silica nanoparticles. Several important parameters affecting the performance of the nanosensor were investigated. Under optimized conditions, the limit of detection was 1.0 ng mL -1 and the linear range 10-160 ng mL -1 . Furthermore, the sensor was suitable for nitrite determination in different food samples. Copyright © 2018 Elsevier Ltd. All rights reserved.

A rapid and sensitive evaluation of nitrite content in Saudi Arabian processed meat and poultry using a novel ultra performance liquid chromatography-mass spectrometry method.

PubMed

Siddiqui, Masoom Raza; Wabaidur, Saikh Mohammad; Khan, Moonis Ali; ALOthman, Zeid A; Rafiquee, M Z A; Alqadami, Ayoub Abdullah

2018-01-01

Quantitative assessment of nitrite (NO 2 - ) anion was performed using a newly developed high throughput ultra performance liquid chromatography-mass spectrometric (UPLC-MS) method. The nitrite determination with the proposed method using micellar mobile phase was unknown. Selected ion reaction mode using negative electrospray ionization was adopted for the identification and quantitative analysis of nitrite. The chromatographic separation was performed using BEH C-18 column and a micellar mobile phase consisted of sodium dodecyl sulphate and acetonitrile in ratio 30:70 was used. The elution of nitrite anion was accomplished in less than 1 min. Under the optimal analysis conditions, the linearity of the developed method was checked in the concentration range of 0.5-20 mg kg -1 NO 2 - with an excellent correlation coefficient of 0.996. The precisions of the method with relative standard deviation <2% was observed when standard at concentration of 1 mg kg -1 was used. The limit of detection and limit of quantitation of the developed mass spectrometric method was found to be 0.114 and 0.346 mg kg -1 , respectively. The developed UPLC/MS method was applied to quantify this anion in processed meats and poultries from various super market of Saudi Arabia (Riyadh region). The recoveries of the nitrite in the various samples were found in the range of 100.03-103.5%.

Nitrite in feed: From Animal health to human health

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cockburn, Andrew; Brambilla, Gianfranco; Fernández, Maria-Luisa

Nitrite is widely consumed from the diet by animals and humans. However the largest contribution to exposure results from the in vivo conversion of exogenously derived nitrate to nitrite. Because of its potential to cause to methaemoglobin (MetHb) formation at excessive levels of intake, nitrite is regulated in feed and water as an undesirable substance. Forages and contaminated water have been shown to contain high levels of nitrate and represent the largest contributor to nitrite exposure for food-producing animals. Interspecies differences in sensitivity to nitrite intoxication principally result from physiological and anatomical differences in nitrite handling. In the case ofmore » livestock both pigs and cattle are relatively susceptible. With pigs this is due to a combination of low levels of bacterial nitrite reductase and hence potential to reduce nitrite to ammonia as well as reduced capacity to detoxify MetHb back to haemoglobin (Hb) due to intrinsically low levels of MetHb reductase. In cattle the sensitivity is due to the potential for high dietary intake and high levels of rumen conversion of nitrate to nitrite, and an adaptable gut flora which at normal loadings shunts nitrite to ammonia for biosynthesis. However when this escape mechanism gets overloaded, nitrite builds up and can enter the blood stream resulting in methemoglobinemia. Looking at livestock case histories reported in the literature no-observed-effect levels of 3.3 mg/kg body weight (b.w.) per day for nitrite in pigs and cattle were estimated and related to the total daily nitrite intake that would result from complete feed at the EU maximum permissible level. This resulted in margins of safety of 9-fold and 5-fold for pigs and cattle, respectively. Recognising that the bulkiness of animal feed limits their consumption, these margins in conjunction with good agricultural practise were considered satisfactory for the protection of livestock health. A human health risk assessment was also carried out taking into account all direct and indirect sources of nitrite from the human diet, including carry-over of nitrite in animal-based products such as milk, eggs and meat products. Human exposure was then compared with the acceptable daily intake (ADI) for nitrite of 0-0.07 mg/kg b.w. per day. Overall, the low levels of nitrite in fresh animal products represented only 2.9% of the total daily dietary exposure and thus were not considered to raise concerns for human health. It is concluded that the potential health risk to animals from the consumption of feed or to man from eating fresh animal products containing nitrite, is very low.« less

Use of polyurethane foam and 3-hydroxy-7,8-benzo-1,2,3,4-tetrahydroquinoline for determination of nitrite by diffuse reflectance spectroscopy and colorimetry.

PubMed

Apyari, V V; Dmitrienko, S G; Ostrovskaya, V M; Anaev, E K; Zolotov, Y A

2008-07-01

Polyurethane foam (PUF) has been suggested as a solid polymeric reagent for determination of nitrite. The determination is based on the diazotization of end toluidine groups of PUF with nitrite in acidic medium followed by coupling of polymeric diazonium cation with 3-hydroxy-7,8-benzo-1,2,3,4-tetrahydroquinoline. The intensely colored polymeric azodye formed in this reaction can be used as a convenient analytic form for the determination of nitrite by diffuse reflectance spectroscopy (c (min) = 0.7 ng mL(-1)). The possibility of using a desktop scanner, digital camera, and computer data processing for the numerical evaluation of the color intensity of the polymeric azodye has been investigated. A scanner and digital camera can be used for determination of nitrite with the same sensitivity and reproducibility as with diffuse reflectance spectroscopy. The approach developed was applied for determination of nitrite in river water and human exhaled breath condensate.

Determination of five abused drugs in nitrite-adulterated urine by immunoassays and gas chromatography-mass spectrometry.

PubMed

Tsai, S C; ElSohly, M A; Dubrovsky, T; Twarowska, B; Towt, J; Salamone, S J

1998-10-01

The adulteration of urine specimens with nitrite ion hasseen shown to mask the gas chromatography-mass spectrometry (GC-MS) confirmation testing of marijuana use. This study was designed to further investigate the effect of nitrite adulteration on the detection of five commonly abused drugs by immunoassay screening and GC-MS analysis. The drugs tested are cocaine metabolite (benzoylecgonine), morphine, 11-nor-delta-tetrahydrocannabinol-9-carboxylic acid (THCCOOH), amphetamine, and phencyclidine. The immunoassays evaluated included the instrument-based Abuscreen ONLINE assays, the on-site Abuscreen ONTRAK assays, and the one-step ONTRAK TESTCUP-5 assay. Multianalyte standards containing various levels of drugs were used to test the influence of both potassium and sodium nitrite. In the ONLINE immunoassays, the presence of up to 1.0M nitrite in the multianalyte standards had no significant effect for benzoylecgonine, morphine, and phencyclidine assays. With a high concentration of nitrite, ONLINE became more sensitive for amphetamine (detected more drug than what was expected) and less sensitive for THCCOOH (detected less drug than what was expected). No effects of nitrite were observed on the results of the Abuscreen ONTRAK assays. Similarly, no effects were observed on the absolute qualitative results of the TESTCUP-5 when testing the nitrite-adulterated standards. However, the produced intensities of the signals that indicate the negative test results were slightly lowered in the THC and phencyclidine assays. The presence of 1.0M of nitrite did not show dramatic interference with the GC-MS analysis of benzoylecgonine, morphine, amphetamine, and phencyclidine. In contrast, nitrite ion significantly interfered with the detection of THCCOOH by GC-MS. The presence of 0.03M of nitrite ion resulted in significant loss in the recovery of THCCOOH and its internal standard by GC-MS. The problem of nitrite adulteration could be alleviated by sodium bisulfite treatment even when the specimens were spiked with 1.0M of nitrite ion. Although bisulfite treatment decomposed all nitrite ions in the sample to recover the remaining THCCOOH by GC-MS, the net recovery of THCCOOH depended on urinary pH and time and conditions of sample storage. The presence of nitrite concentrations that might arise from all possible natural sources, including microorganisms, pathological conditions, and medications, did not interfere with the GC-MS analysis of THCCOOH.

Mechanisms for cellular NO oxidation and nitrite formation in lung epithelial cells.

PubMed

Zhao, Xue-Jun; Wang, Ling; Shiva, Sruti; Tejero, Jesus; Myerburg, Mike M; Wang, Jun; Frizzell, Sam; Gladwin, Mark T

2013-08-01

Airway lining fluid contains relatively high concentrations of nitrite, and arterial blood levels of nitrite are higher than venous levels, suggesting the lung epithelium may represent an important source of nitrite in vivo. To investigate whether lung epithelial cells possess the ability to convert NO to nitrite by oxidation, and the effect of oxygen reactions on nitrite formation, the NO donor DETA NONOate was incubated with or without A549 cells or primary human bronchial epithelial (HBE) cells for 24 h under normoxic (21% O2) and hypoxic (1% O2) conditions. Nitrite production was significantly increased under all conditions in the presence of A549 or HBE cells, suggesting that both A549 and HBE cells have the capacity to oxidize NO to nitrite even under low-oxygen conditions. The addition of oxyhemoglobin to the A549 cell medium decreased the production of nitrite, consistent with NO scavenging limiting nitrite formation. Heat-denatured A549 cells produced much lower nitrite and nitrate, suggesting an enzymatic activity is required. This NO oxidation activity was highest in membrane-bound proteins with molecular size <100kDa. In addition, 1H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one and cyanide inhibited formation of nitrite in A549 cells. It has been shown that ceruloplasmin (Cp) possesses an NO oxidase and nitrite synthase activity in plasma based on NO oxidation to nitrosonium cation. We observed that Cp is expressed intracellularly in lung epithelial A549 cells and secreted into the medium under basal conditions and during cytokine stimulation. However, an analysis of Cp expression level and activity measured via p-phenylenediamine oxidase activity assay revealed very low activity compared with plasma, suggesting that there is insufficient Cp to contribute to detectable NO oxidation to nitrite in A549 cells. Additionally, Cp levels were knocked down using siRNA by more than 75% in A549 cells, with no significant change in either nitrite or cellular S-nitrosothiol formation compared to scrambled siRNA control under basal conditions or cytokine stimulation. These data suggest that lung epithelial cells possess NO oxidase activity, which is enhanced in cell-membrane-associated proteins and not regulated by intracellular or secreted Cp, indicating that alternative NO oxidases determine hypoxic and normoxic nitrite formation from NO in human lung epithelial cells. Copyright © 2013 The Authors. Published by Elsevier Inc. All rights reserved.

Effects of T-state and R-state stabilization on deoxyhemoglobin-nitrite reactions and stimulation of nitric oxide signaling

PubMed Central

Cantu-Medellin, Nadiezhda; Vitturi, Dario A.; Rodriguez, Cilina; Murphy, Serena; Dorman, Scott; Shiva, Sruti; Zhou, Yipin; Jia, Yiping; Palmer, Andre F.; Patel, Rakesh P.

2011-01-01

Recent data suggest that transitions between the relaxed (R) and tense (T) state of hemoglobin control the reduction of nitrite to nitric oxide (NO) by deoxyhemoglobin. This reaction may play a role in physiologic NO homeostasis and be a novel consideration for the development of the next generation of hemoglobin-based blood oxygen carriers (HBOCs, i.e. artificial blood substitutes). Herein we tested the effects of chemical stabilization of bovine hemoglobin in either the T- (THb) or R-state (RHb) on nitrite reduction kinetics, NO-gas formation and ability to stimulate NO-dependent signaling. These studies were performed over a range of fractional saturations that is expected to mimic biological conditions. The initial rate for nitrite-reduction decreased in the following order RHb > bHb > THb, consistent with the hypothesis that the rate constant for nitrite reduction is faster with R-state Hb and slower with T-state Hb. Moreover, RHb produced more NO-gas and inhibited mitochondrial respiration more potently than both bHb and THb. Interestingly, at low oxygen fractional saturations, THb produced more NO and stimulated nitrite-dependent vasodilation more potently than bHb despite both derivatives having similar initial rates for nitrite reduction and a more negative reduction potential in THb versus bHb. These data suggest that cross-linking of bovine hemoglobin in the T-state conformation leads to a more effective coupling of nitrite reduction to NO-formation. Our results support the model of allosteric regulation of nitrite reduction by deoxyhemoglobin and show that cross-linking hemoglobins in distinct quaternary states can generate products with increased NO yields from nitrite reduction that could be harnessed to promote NO-signaling in vivo. PMID:21277987

Iron(II) porphyrins induced conversion of nitrite into nitric oxide: A computational study.

PubMed

Zhang, Ting Ting; Liu, Yong Dong; Zhong, Ru Gang

2015-09-01

Nitrite reduction to nitric oxide by heme proteins was reported as a protective mechanism to hypoxic injury in mammalian physiology. In this study, the pathways of nitrite reduction to nitric oxide mediated by iron(II) porphyrin (P) complexes, which were generally recognized as models for heme proteins, were investigated by using density functional theory (DFT). In view of two type isomers of combination of nitrite and Fe(II)(P), N-nitro- and O-nitrito-Fe(II)-porphyrin complexes, and two binding sites of proton to the different O atoms of nitrite moiety, four main pathways for the conversion of nitrite into nitric oxide mediated by iron(II) porphyrins were proposed. The results indicate that the pathway of N-bound Fe(II)(P)(NO2) isomer into Fe(III)(P)(NO) and water is similar to that of O-bound isomer into nitric oxide and Fe(III)(P)(OH) in both thermodynamical and dynamical aspects. Based on the initial computational studies of five-coordinate nitrite complexes, the conversion of nitrite into NO mediated by Fe(II)(P)(L) complexes with 14 kinds of proximal ligands was also investigated. Generally, the same conclusion that the pathways of N-bound isomers are similar to those of O-bound isomer was obtained for iron(II) porphyrin with ligands. Different effects of ligands on the reduction reactions were also found. It is notable that the negative proximal ligands can improve reactive abilities of N-nitro-iron(II) porphyrins in the conversion of nitrite into nitric oxide compared to neutral ligands. The findings will be helpful to expand our understanding of the mechanism of nitrite reduction to nitric oxide by iron(II) porphyrins. Copyright © 2015 Elsevier Inc. All rights reserved.

Development of a cloud point extraction and spectrophotometry-based microplate method for the determination of nitrite in human urine and blood.

PubMed

Zhao, Jiao; Lu, Yunhui; Fan, Chongyang; Wang, Jun; Yang, Yaling

2015-02-05

A novel and simple method for the sensitive determination of trace amounts of nitrite in human urine and blood has been developed by combination of cloud point extraction (CPE) and microplate assay. The method is based on the Griess reaction and the reaction product is extracted into nonionic surfactant Triton-X114 using CPE technique. In this study, decolorization treatment of urine and blood was applied to overcome the interference of matrix and enhance the sensitivity of nitrite detection. Multi-sample can be simultaneously detected thanks to a 96-well microplate technique. The effects of different operating parameters such as type of decolorizing agent, concentration of surfactant (Triton X-114), addition of (NH4)2SO4, extraction temperature and time, interfering elements were studied and optimum conditions were obtained. Under the optimum conditions, a linear calibration graph was obtained in the range of 10-400 ng mL(-1) of nitrite with limit of detection (LOD) of 2.5 ng mL(-1). The relative standard deviation (RSD) for determination of 100 ng mL(-1) of nitrite was 2.80%. The proposed method was successfully applied for the determination of nitrite in the urine and blood samples with recoveries of 92.6-101.2%. Copyright © 2014 Elsevier B.V. All rights reserved.

Contamination Detection and Mitigation Strategies for Unsymmetric Dimethylhydrazine/Nitrogen Tetroxide Non-Combustion Product Residues

NASA Technical Reports Server (NTRS)

Greene, Benjamin; Buchanan, Vanessa D.; Baker, David L.

2006-01-01

Dimethylamine and nitrite, which are non-combustion reaction products of unsymmetrical dimethylhydrazine (UDMH) and nitrogen tetroxide (NTO) propellants, can contaminate spacesuits during extra-vehicular activity (EVA) operations. They can react with water in the International Space Station (ISS) airlock to form N-nitrosodimethylamine (NDMA), a carcinogen. Detection methods for assessing nitrite and dimethylamine contamination were investigated. The methods are based on color-forming reactions in which intensity of color is proportional to concentration. A concept color detection kit using a commercially available presumptive field test for methamphetamine coupled with nitrite test strips was developed and used to detect dimethylamine and nitrite. Contamination mitigation strategies were also developed.

A new catalytic-spectrophotometric method for quantification of trace amounts of nitrite in fruit juice samples.

PubMed

Sobhanardakani, S; Farmany, A; Abbasi, S; Cheraghi, J; Hushmandfar, R

2013-03-01

A new kinetic method has been developed for the determination of nitrite in fruit juice samples. The method is based on the catalytic effect of nitrite with the oxidation of Nile Blue A (NBA) by KBrO(3) in the sulfuric acid medium. The optimum conditions obtained are 1.2 mM sulfuric acid, 0.034 mM of NBA, 2.8 × 10(-3) M KBrO(3), reaction temperature of 20 °C, and reaction time of 100 s at 595.5 nm. Under the optimized conditions, the method allowed the quantification of nitrite in a range of 0.2-800 μg/mL with a detection limit of 0.02 μg/mL. The method was applied to the determination of nitrite in 15 brands of fruit juice samples.

Crystallography with online optical and X-ray absorption spectroscopies demonstrates an ordered mechanism in copper nitrite reductase.

PubMed

Hough, Michael A; Antonyuk, Svetlana V; Strange, Richard W; Eady, Robert R; Hasnain, S Samar

2008-04-25

Nitrite reductases are key enzymes that perform the first committed step in the denitrification process and reduce nitrite to nitric oxide. In copper nitrite reductases, an electron is delivered from the type 1 copper (T1Cu) centre to the type 2 copper (T2Cu) centre where catalysis occurs. Despite significant structural and mechanistic studies, it remains controversial whether the substrates, nitrite, electron and proton are utilised in an ordered or random manner. We have used crystallography, together with online X-ray absorption spectroscopy and optical spectroscopy, to show that X-rays rapidly and selectively photoreduce the T1Cu centre, but that the T2Cu centre does not photoreduce directly over a typical crystallographic data collection time. Furthermore, internal electron transfer between the T1Cu and T2Cu centres does not occur, and the T2Cu centre remains oxidised. These data unambiguously demonstrate an 'ordered' mechanism in which electron transfer is gated by binding of nitrite to the T2Cu. Furthermore, the use of online multiple spectroscopic techniques shows their value in assessing radiation-induced redox changes at different metal sites and demonstrates the importance of ensuring the correct status of redox centres in a crystal structure determination. Here, optical spectroscopy has shown a very high sensitivity for detecting the change in T1Cu redox state, while X-ray absorption spectroscopy has reported on the redox status of the T2Cu site, as this centre has no detectable optical absorption.

Atmospheric deposition of selected chemicals and their effect on nonpoint-source pollution in the Twin Cities Metropolitan Area, Minnesota

USGS Publications Warehouse

Brown, R.G.

1984-01-01

The atmospheric contribution to nonpoint-source-runoff pollution of nitrogen, in the form of nitrite-plus-nitrate, and lead was extremely high contributing as much as 84 percent of the runoff load. In contrast, phosphorus and chloride inputs were low averaging of 6 percent of the total runoff load. Future investigations of nonpoint-source pollution in runoff might include collection of data on atmospheric deposition of nitrite-plus-nitrate nitrogen and lead because of the importance of that source of these constituents in runoff.

Nitrogen isotope fractionation during archaeal ammonia oxidation: Coupled estimates from isotopic measurements of ammonium and nitrite

NASA Astrophysics Data System (ADS)

Mooshammer, Maria; Stieglmeier, Michaela; Bayer, Barbara; Jochum, Lara; Melcher, Michael; Wanek, Wolfgang

2014-05-01

Ammonia-oxidizing archaea (AOA) are ubiquitous in marine and terrestrial environments and knowledge about the nitrogen (N) isotope effect associated with their ammonia oxidation activity will allow a better understanding of natural abundance isotope ratios, and therefore N transformation processes, in the environment. Here we examine the kinetic isotope effect for ammonia oxidation in a pure soil AOA culture (Ca. Nitrososphaera viennensis) and a marine AOA enrichment culture. We estimated the isotope effect from both isotopic signatures of ammonium and nitrite over the course of ammonia oxidation. Estimates of the isotope effect based on the change in the isotopic signature of ammonium give valuable insight, because these estimates are not subject to the same concerns (e.g., accumulation of an intermediate) as estimates based on isotopic measurements of nitrite. Our results show that both the pure soil AOA culture and a marine AOA enrichment culture have similar but substantial isotope effect during ammonia consumption (31-34 per mill; based on ammonium) and nitrite production (43-45 per mill; based on nitrite). The 15N fractionation factors of both cultures tested fell in the upper range of the reported isotope effects for archaeal and bacterial ammonia oxidation (10-41 per mill) or were even higher than those. The isotope fractionation for nitrite production was significantly larger than for ammonium consumption, indicating that (1) some intermediate (e.g., hydroxylamine) of ammonia oxidation accumulates, allowing for a second 15N fractionation step to be expressed, (2) a fraction of ammonia oxidized is lost via gaseous N forms (e.g., NO or N2O), which is 15N-enriched or (3) a fraction of ammonium is assimilated into AOA biomass, biomass becoming 15N-enriched. The significance of these mechanisms will be explored in more detail for the soil AOA culture, based on isotope modeling and isotopic measurements of biomass and N2O.

Investigation on the photoreactions of nitrate and nitrite ions with selected azaarenes in water

PubMed

Beitz; Bechmann; Mitzner

1999-01-01

The photoreactions of selected azaarenes with nitrate and nitrite ions were investigated under irradiation at lambda = 313 nm. The excitation of both anions leads to several photochemical reactions forming mainly hydroxyl radicals and nitrogen oxides. The purification capability of natural waters i.e. the oxidation of inorganic and organic substances results from the formation of hydroxyl radicals. Nitrated isomers of azaarenes were found among the main products of the investigated photoreactions. The nitrogen oxides were responsible for the production of nitrated derivatives which possess a high toxic potential. Their formation was explained by the parallel occurance of two mechanism, a molecular and a radical one. The molecular mechanism became more important with increasing ionisation potentials of the azaarenes. The spectrum of oxidized products corresponded to the one got in the photoreactions of azaarenes with hydrogen peroxide. The formation of several oxidation and nitration products of the pyridine ring with its low electron density was explained by the reaction of excited states of azaarenes. The photoreactions with nitrite ions only led to the formation of oxidized and nitrated products. Nitroso products were not formed. The reactivity of nitrogen monoxide is too low for its reaction with the azaarenes.

A high-throughput headspace gas chromatographic technique for the determination of nitrite content in water samples.

PubMed

Zhang, Shu-Xin; Peng, Rong; Jiang, Ran; Chai, Xin-Sheng; Barnes, Donald G

2018-02-23

This paper reports on a high-throughput headspace gas chromatographic method (HS-GC) for the determination of nitrite content in water sample, based on GC measurement of cyclohexene produced from the reaction between nitrite and cyclamate in a closed vial. The method has a relative standard deviation of <3.5%; The differences between the results of the nitrite measurements obtained by this method and those of a reference method were less than 5.8% and the recoveries of the method were in the range of 94.8-102% (for a spiked nitrite content range from 0.002 to 0.03 mg/L). The limit of detection of the method was 0.46 μg L -1 . Due to an overlapping mode in the headspace auto-sampler system, the method can provide an automated and high-throughput nitrite analysis for the surface water samples. In short, the present HS-GC method is simple, accurate, and sensitive, and it is very suitable to be used in the batch sample testing. Copyright © 2018 Elsevier B.V. All rights reserved.

Potency of Purple Sweet Potato’s Anthocyanin as Biosensor for Detection of Chemicals in Food Products

NASA Astrophysics Data System (ADS)

Wulandari, A.; Sunarti, TC; Fahma, F.; Noor, E.

2018-05-01

Bioactive compounds such as anthocyanin are a natural ingredient that produces color with typical specificity. Anthocyanin from Ayamurasaki purple sweet potato (Ipomoea batatas L.) was extracted in ethanol and used as crude anthocyanin extracts. The color of bioactive anthocyanin can be used as a biosensor to detect chemical of food products because it provides a unique color change. However, the each bioactive has a particular sensitivity and selectivity to a specific chemical, so it is necessary to select and test the selectivity. Six chemicals, which were sodium nitrite, sodium benzoate, sodium cyclamate (food additives), formalin, borax (illegal food preservatives), and residue fertilizer (urea) were tested and observed for its color change. The results showed that the bioactive anthocyanin of purple sweet potato with the concentration of ± 42.65 ppm had better selectivity and sensitivity to sodium nitrite with a detection limit of 100 ppm, where the color change response time ranged from 15-20 minutes. The selectivity and sensitivity of this bioactive can be used as the basic information for the development of biosensor.

Performance of the dipstick screening test as a predictor of negative urine culture

PubMed Central

Marques, Alexandre Gimenes; Doi, André Mario; Pasternak, Jacyr; Damascena, Márcio dos Santos; França, Carolina Nunes; Martino, Marinês Dalla Valle

2017-01-01

ABSTRACT Objective To investigate whether the urine dipstick screening test can be used to predict urine culture results. Methods A retrospective study conducted between January and December 2014 based on data from 8,587 patients with a medical order for urine dipstick test, urine sediment analysis and urine culture. Sensitivity, specificity, positive and negative predictive values were determined and ROC curve analysis was performed. Results The percentage of positive cultures was 17.5%. Nitrite had 28% sensitivity and 99% specificity, with positive and negative predictive values of 89% and 87%, respectively. Leukocyte esterase had 79% sensitivity and 84% specificity, with positive and negative predictive values of 51% and 95%, respectively. The combination of positive nitrite or positive leukocyte esterase tests had 85% sensitivity and 84% specificity, with positive and negative predictive values of 53% and 96%, respectively. Positive urinary sediment (more than ten leukocytes per microliter) had 92% sensitivity and 71% specificity, with positive and negative predictive values of 40% and 98%, respectively. The combination of nitrite positive test and positive urinary sediment had 82% sensitivity and 99% specificity, with positive and negative predictive values of 91% and 98%, respectively. The combination of nitrite or leukocyte esterase positive tests and positive urinary sediment had the highest sensitivity (94%) and specificity (84%), with positive and negative predictive values of 58% and 99%, respectively. Based on ROC curve analysis, the best indicator of positive urine culture was the combination of positives leukocyte esterase or nitrite tests and positive urinary sediment, followed by positives leukocyte and nitrite tests, positive urinary sediment alone, positive leukocyte esterase test alone, positive nitrite test alone and finally association of positives nitrite and urinary sediment (AUC: 0.845, 0.844, 0.817, 0.814, 0.635 and 0.626, respectively). Conclusion A negative urine culture can be predicted by negative dipstick test results. Therefore, this test may be a reliable predictor of negative urine culture. PMID:28444086

Rapid determination of nitrites in food using a diffuse UV-visible reflectance method.

PubMed

Khan, S; Vila, M M D C; Tubino, M

2012-08-01

A simple, low-cost, sensitive and selective method for the determination of trace quantities of nitrite in foods such as cheese and cured meat using diffuse ultraviolet-visible reflectance was developed. It is based on the reaction of nitrite with sulphadiazine and α-naphthol, which produces a coloured product in basic medium. The reaction is carried out directly in the measuring cell. For cheese the limit of detection (LOD), expressed as NaNO₂, was estimated to be about 2.0 × 10⁻²mg l⁻¹ (2.9 × 10⁻⁷mol l⁻¹) in the final measuring solution and 0.17 mg kg⁻¹ in cheese (2.5 × 10⁻⁶mol kg⁻¹). The relative standard deviation (RSD) varied from 5% to 8% depending on the sample. For meat the LOD was estimated to be about 2.0 × 10⁻²mg l⁻¹ (2.9 × 10⁻⁷mol l⁻¹) in the final measuring solution and 0.13 mg kg⁻¹ in meat (1.9 × 10⁻⁶mol kg⁻¹). The RSD varied from 3% to 6% depending on the sample. The results of the proposed method were also compared with those obtained with the official method using the statistical Student's t-test and F-test procedures.

Evaluation of induced color changes in chicken breast meat during simulation of pink color defect.

PubMed

Holownia, K; Chinnan, M S; Reynolds, A E; Koehler, P E

2003-06-01

The objective of the study was to establish a pink threshold and simulate the pink defect in cooked chicken breast meat with treatment combinations that would induce significant changes in the color of raw and cooked meat. The subjective pink threshold used in judging pink discoloration was established at a* = 3.8. Samples of three color groups (normal, lighter than normal, and darker than normal) of boneless, skinless chicken breast muscles were selected based on instrumental color values. The in situ changes were induced using sodium chloride, sodium tripolyphosphate, sodium erythorbate, and sodium nitrite at two levels: present and not present. Fillets in all treatments were subjected to individual injections, followed by tumbling, cooking, and chilling. Samples were analyzed for color [lightness (L*), red/green axis (a*), yellow/blue axis (b*)] and reflectance spectra. Simulation of the pink defect was achieved in eight of the 16 treatment combinations when sodium nitrite was present and in an additional two treatment combinations when it was absent. Pinking in cooked samples was affected (P < 0.05) by L* of raw meat color. Results confirmed that it was possible to simulate the undesired pinking in cooked chicken white meat when in situ conditions were induced by sodium chloride, sodium tripolyphosphate, and sodium nitrite. The continuation of the simulation study can aid in developing alternative processing methods to eliminate potential pink defects.

Effect of tomato paste and nitrite level on processing and quality characteristics of frankfurters.

PubMed

Deda, M S; Bloukas, J G; Fista, G A

2007-07-01

Fourteen treatments of frankfurters (18% fat) were produced with two levels of sodium nitrite, 0 and 150mg/kg (0.015%), and seven levels (0%,2%,6%,8%,12% and 16%) of tomato paste with 12% soluble solids The higher the tomato paste level the higher the preference of consumers for frankfurters based on their colour. Frankfurters with 16% tomato paste had a sour taste while those with 12% tomato paste were the most acceptable. In a 2nd experiment three treatments of frankfurters (18% fat) were produced with 0, 50 and 100mg/kg of sodium nitrite and 12% tomato paste and a fourth (control) with only 150mg/kg sodium nitrite. Treatments with 12% tomato paste had lower (p<0.05) pH values and residual nitrite, and higher (p<0.05) thiobarbituric acid values, lightness and yellowness than control. Frankfurters with reduced levels of sodium nitrite (50 and 100mg/kg) and 12% tomato paste had the highest (p<0.05) redness. Storage time affected (p<0.05) all quality attributes. The nitrites added to frankfurters can be reduced from 150mg/kg to 100mg/kg in combination with 12% tomato paste without any negative effect on the quality of the product.

Effects of Bacterial Community Members on the Proteome of the Ammonia-Oxidizing Bacterium Nitrosomonas sp. Strain Is79

PubMed Central

Sedlacek, Christopher J.; Nielsen, Susanne; Greis, Kenneth D.; Haffey, Wendy D.; Revsbech, Niels Peter; Ticak, Tomislav; Laanbroek, Hendrikus J.

2016-01-01

ABSTRACT Microorganisms in the environment do not exist as the often-studied pure cultures but as members of complex microbial communities. Characterizing the interactions within microbial communities is essential to understand their function in both natural and engineered environments. In this study, we investigated how the presence of a nitrite-oxidizing bacterium (NOB) and heterotrophic bacteria affect the growth and proteome of the chemolithoautotrophic ammonia-oxidizing bacterium (AOB) Nitrosomonas sp. strain Is79. We investigated Nitrosomonas sp. Is79 in co-culture with Nitrobacter winogradskyi, in co-cultures with selected heterotrophic bacteria, and as a member of the nitrifying enrichment culture G5-7. In batch culture, N. winogradskyi and heterotrophic bacteria had positive effects on the growth of Nitrosomonas sp. Is79. An isobaric tag for relative and absolute quantification (iTRAQ) liquid chromatography-tandem mass spectrometry (LC-MS/MS) proteomics approach was used to investigate the effect of N. winogradskyi and the co-cultured heterotrophic bacteria from G5-7 on the proteome of Nitrosomonas sp. Is79. In co-culture with N. winogradskyi, several Nitrosomonas sp. Is79 oxidative stress response proteins changed in abundance, with periplasmic proteins increasing and cytoplasmic proteins decreasing in abundance. In the presence of heterotrophic bacteria, the abundance of proteins directly related to the ammonia oxidation pathway increased, while the abundance of proteins related to amino acid synthesis and metabolism decreased. In summary, the proteome of Nitrosomonas sp. Is79 was differentially influenced by the presence of either N. winogradskyi or heterotrophic bacteria. Together, N. winogradskyi and heterotrophic bacteria reduced the oxidative stress for Nitrosomonas sp. Is79, which resulted in more efficient metabolism. IMPORTANCE Aerobic ammonia-oxidizing microorganisms play an important role in the global nitrogen cycle, converting ammonia to nitrite. In their natural environment, they coexist and interact with nitrite oxidizers, which convert nitrite to nitrate, and with heterotrophic microorganisms. The presence of nitrite oxidizers and heterotrophic bacteria has a positive influence on the growth of the ammonia oxidizers. Here, we present a study investigating the effect of nitrite oxidizers and heterotrophic bacteria on the proteome of a selected ammonia oxidizer in a defined culture to elucidate how these two groups improve the performance of the ammonia oxidizer. The results show that the presence of a nitrite oxidizer and heterotrophic bacteria reduced the stress for the ammonia oxidizer and resulted in more efficient energy generation. This study contributes to our understanding of microbe-microbe interactions, in particular between ammonia oxidizers and their neighboring microbial community. PMID:27235442

Contrasting effects of low versus high ascorbate doses on blood pressure responses to oral nitrite in L-NAME-induced hypertension.

PubMed

Pinheiro, Lucas C; Ferreira, Graziele C; Vilalva, Kelvin H; Toledo, José C; Tanus-Santos, Jose E

2018-04-01

Nitrite reduces blood pressure (BP) in both clinical and experimental hypertension. This effect is attributable to the formation of nitric oxide (NO) and other NO-related species, which may be improved by ascorbate or other antioxidants. However, the BP responses to oral nitrite result, at least in part, of increased gastric S-nitrosothiol formation. This study tested the hypothesis that ascorbate may destroy S-nitrosothiols and therefore not all doses of ascorbate enhance the BP responses to oral nitrite. We assessed the BP responses to oral sodim nitrite (0.2 mmol/kg) in L-NAME hypertensive rats pretreated with ascorbate (0, 0.02, 0.2, or 2 mmol/kg). Plasma and gastric wall concentrations of nitrite and nitroso compounds concentrations were determined using an ozone-based reductive chemiluminescence assay. Nitrate concentrations were determined using the Griess reaction. Free thiol concentrations were determined by a colorimetric assay. The BP responses to nitrite exhibited a bell-shape profile as they were not modified by ascorbate 0.02 mmol/l, whereas the 0.2 mmol/kg dose enhanced and the 2 mmol/kg dose attenuated BP responses. In parallel with BP responses, nitrite-induced increases in plasma nitrite and RSNO species were not modified by ascorbate 0.02 mmol/l, whereas the 0.2 mmol/kg dose enhanced and the 2 mmol/kg dose attenuated them. Similar experiments were carried out with an equimolar dose of S-nitrosogluthathione. Ascorbate dose-dependently impaired the BP responses to S-nitrosogluthathione, and the corresponding increases in plasma RSNO, but not in plasma nitrite concentrations. This is the first study to show that while ascorbate dose-dependently impairs the BP responses to oral S-nitrosogluthathione, there are contrasting effects when low versus high ascorbate doses are compared with respect to its effects on the blood pressure responses to oral nitrite administration. Our findings may have special implications to patients taking ascorbate, as high doses of this vitamin may impair protective mechanisms associated with nitrite or nitrate from dietary sources. Copyright © 2018 Elsevier Inc. All rights reserved.

Ingested nitrate and nitrite and stomach cancer risk: an updated review.

PubMed

Bryan, Nathan S; Alexander, Dominik D; Coughlin, James R; Milkowski, Andrew L; Boffetta, Paolo

2012-10-01

Nitrite and nitrate are naturally occurring molecules in vegetables and also added to cured and processed meats to delay spoilage and pathogenic bacteria growth. Research over the past 15 years has led to a paradigm change in our ideas about health effects of both nitrite and nitrate. Whereas, historically nitrite and nitrate were considered harmful food additives and listed as probable human carcinogens under conditions where endogenous nitrosation could take place, they are now considered by some as indispensible nutrients essential for cardiovascular health by promoting nitric oxide (NO) production. We provide an update to the literature and knowledge base concerning their safety. Most nitrite and nitrate exposure comes from naturally occurring and endogenous sources and part of the cell signaling effects of NO involve nitrosation. Nitrosation must now be considered broadly in terms of both S- and N-nitrosated species, since S-nitrosation is kinetically favored. Protein S-nitrosation is a significant part of the role of NO in cellular signal transduction and is involved in critical aspects of cardiovascular health. A critical review of the animal toxicology literature of nitrite indicates that in the absence of co-administration of a carcinogenic nitrosamine precursor, there is no evidence for carcinogenesis. Newly published prospective epidemiological cohort studies indicate that there is no association between estimated intake of nitrite and nitrate in the diet and stomach cancer. This new and growing body of evidence calls for a reconsideration of nitrite and nitrate safety. Copyright © 2012 Elsevier Ltd. All rights reserved.

Percentile Distributions of Median Nitrite Plus Nitrate as Nitrogen, Total Nitrogen, and Total Phosphorus Concentrations in Oklahoma Streams, 1973-2001

USGS Publications Warehouse

Haggard, Brian E.; Masoner, Jason R.; Becker, Carol J.

2003-01-01

Nutrients are one of the primary causes of water-quality impairments in streams, lakes, reservoirs, and estuaries in the United States. The U.S. Environmental Protection Agency has developed regional-based nutrient criteria using ecoregions to protect streams in the United States from impairment. However, nutrient criteria were based on nutrient concentrations measured in large aggregated nutrient ecoregions with little relevance to local environmental conditions in states. The Oklahoma Water Resources Board is using a dichotomous process known as Use Support Assessment Protocols to define nutrient criteria in Oklahoma streams. The Oklahoma Water Resources Board is modifying the Use Support Assessment Protocols to reflect nutrient informa-tion and environmental characteristics relevant to Oklahoma streams, while considering nutrient information grouped by geographic regions based on level III ecoregions and state boundaries. Percentile distributions of median nitrite plus nitrate as nitrogen, total nitrogen, and total phosphorous concentrations were calculated from 563 sites in Oklahoma and 4 sites in Arkansas near the Oklahoma and Arkansas border to facilitate development of nutrient criteria for Oklahoma streams. Sites were grouped into four geographic regions and were categorized into eight stream categories by stream slope and stream order. The 50th percentiles of median nitrite plus nitrate as nitrogen, total nitrogen, and total phosphorus concentrations were greater in the Ozark Highland ecoregion and were less in the Ouachita Mountains ecoregion when compared to other geographic areas used to group sites. The 50th percentiles of median concentrations of nitrite plus nitrate as nitrogen, total nitrogen, and total phosphorus were least in first, second, and third order streams. The 50th percentiles of median nitrite plus nitrate as nitrogen, total nitrogen and total phosphorus concentrations in the Ozark Highland and Ouachita Mountains ecoregions were least in first, second, and third order streams with streams slopes greater than 17 feet per mile. Nitrite plus nitrate as nitrogen and total nitrogen criteria determined by the U.S. Environmental Protection Agency for the Ozark Highland ecoregion were less than the 25th percentiles of median nitrite plus nitrate as nitrogen, total nitrogen, and total phosphorus concentrations in the Ozark Highland ecoregion calculated for this report. Nitrite plus nitrate as nitrogen and total nitrogen criteria developed by the U.S. Environmental Protection Agency for the Ouachita Mountains ecoregion were similar to the 25th percentiles of median nitrite plus nitrate as nitrogen and total nitrogen concentrations in the Ouachita Mountains ecoregion calculated for this report. Nitrate as nitrogen and total phosphorus concentrations currently (2002) used in the Use Support Assessment Protocols for Oklahoma were greater than the 75th percentiles of median nitrite plus nitrate as nitrogen and total phosphorus concentrations calculated for this report.

Monofluorophosphate is a selective inhibitor of respiratory sulfate-reducing microorganisms.

PubMed

Carlson, Hans K; Stoeva, Magdalena K; Justice, Nicholas B; Sczesnak, Andrew; Mullan, Mark R; Mosqueda, Lorraine A; Kuehl, Jennifer V; Deutschbauer, Adam M; Arkin, Adam P; Coates, John D

2015-03-17

Despite the environmental and economic cost of microbial sulfidogenesis in industrial operations, few compounds are known as selective inhibitors of respiratory sulfate reducing microorganisms (SRM), and no study has systematically and quantitatively evaluated the selectivity and potency of SRM inhibitors. Using general, high-throughput assays to quantitatively evaluate inhibitor potency and selectivity in a model sulfate-reducing microbial ecosystem as well as inhibitor specificity for the sulfate reduction pathway in a model SRM, we screened a panel of inorganic oxyanions. We identified several SRM selective inhibitors including selenate, selenite, tellurate, tellurite, nitrate, nitrite, perchlorate, chlorate, monofluorophosphate, vanadate, molydate, and tungstate. Monofluorophosphate (MFP) was not known previously as a selective SRM inhibitor, but has promising characteristics including low toxicity to eukaryotic organisms, high stability at circumneutral pH, utility as an abiotic corrosion inhibitor, and low cost. MFP remains a potent inhibitor of SRM growing by fermentation, and MFP is tolerated by nitrate and perchlorate reducing microorganisms. For SRM inhibition, MFP is synergistic with nitrite and chlorite, and could enhance the efficacy of nitrate or perchlorate treatments. Finally, MFP inhibition is multifaceted. Both inhibition of the central sulfate reduction pathway and release of cytoplasmic fluoride ion are implicated in the mechanism of MFP toxicity.

Quantifying the sources and sinks of nitrite in the oxygen minimum zone of the Eastern Tropical South Pacific

NASA Astrophysics Data System (ADS)

Ji, Qixing; Widner, Brittany; Jayakumar, Amal; Ward, Bess; Mulholland, Margaret

2017-04-01

In coastal upwelling regions, high surface productivity leads to high export and intense remineralization consuming oxygen. This, in combination with slow ventilation, creates oxygen minimum zones (OMZ) in eastern boundary regions of the ocean, such as the one off the Peruvian coast in the Eastern Tropical South Pacific. The OMZ is characterized by a layer of high nitrite concentration coinciding with water column anoxia. Sharp oxygen gradients are located above and below the anoxic layer (upper and lower oxyclines). Thus, the OMZ harbors diverse microbial metabolisms, several of which involve the production and consumption of nitrite. The sources of nitrite are ammonium oxidation and nitrate reduction. The sinks of nitrite include anaerobic ammonium oxidation (anammox), canonical denitrification and nitrite oxidation to nitrate. To quantify the sources and sinks of nitrite in the Peruvian OMZ, incubation experiments with 15N-labeled substrates (ammonium, nitrite and nitrate) were conducted on a research cruise in January 2015. The direct measurements of instantaneous nitrite production and consumption rates were compared with ambient nitrite concentrations to evaluate the turnover rate of nitrite in the OMZ. The distribution of nitrite in the water column showed a two-peak structure. A primary nitrite maximum (up to 0.5 μM) was located in the upper oxycline. A secondary nitrite maximum (up to 10 μM) was found in the anoxic layer. A nitrite concentration minimum occurred at the oxic-anoxic interface just below the upper oxycline. For the sources of nitrite, highest rates of ammonium oxidation and nitrate reduction were detected in the upper oxycline, where both nitrite and oxygen concentrations were low. Lower rates of nitrite production were detected within the layer of secondary nitrite maximum. For the sinks of nitrite, the rates of anammox, denitrification and nitrite oxidation were the highest just below the oxic-anoxic interface. Low nitrite consumption rates were also detected within the layer of the secondary nitrite maximum. The imbalances between nitrite production and consumption rates help to explain the distribution of nitrite in the water column. The primary nitrite maximum in the upper oxycline is consistent with ammonium oxidation exceeding nitrite oxidation. Nitrite consumption rates exceeding rates of nitrite production result in the low nitrite concentration at the oxic-anoxic interface. Within the secondary nitrite maximum in the anoxic layer, production and consumption of nitrite are equivalent within measurement error. These low turnover rates suggest the stability of the nitrite pool in the secondary nitrite maximum over long time scales (decades to millennial). These data could be implemented into biogeochemical models to decipher the origin and the evolution of nitrite distribution in the OMZs.

Glocal assessment of integrated wastewater treatment and recovery concepts using partial nitritation/Anammox and microalgae for environmental impacts.

PubMed

Khiewwijit, Rungnapha; Rijnaarts, Huub; Temmink, Hardy; Keesman, Karel J

2018-07-01

This study explored the feasibility and estimated the environmental impacts of two novel wastewater treatment configurations. Both include combined bioflocculation and anaerobic digestion but apply different nutrient removal technologies, i.e. partial nitritation/Anammox or microalgae treatment. The feasibility of such configurations was investigated for 16 locations worldwide with respect to environmental impacts, such as net energy yield, nutrient recovery and effluent quality, CO 2 emission, and area requirements. The results quantitatively support the applicability of partial nitritation/Anammox in tropical regions and some locations in temperate regions, whereas microalgae treatment is only applicable the whole year round in tropical regions that are close to the equator line. Microalgae treatment has an advantage over the configuration with partial nitritation/Anammox with respect to aeration energy and nutrient recovery, but not with area requirements. Differential sensitivity analysis points out the dominant influence of microalgal biomass yield and wastewater nutrient concentrations on area requirements and effluent quality. This study provides initial selection criteria for worldwide feasibility and corresponding environmental impacts of these novel municipal wastewater treatment plant configurations. Copyright © 2018. Published by Elsevier B.V.

Dependence of nitrite oxidation on nitrite and oxygen in low-oxygen seawater

NASA Astrophysics Data System (ADS)

Sun, Xin; Ji, Qixing; Jayakumar, Amal; Ward, Bess B.

2017-08-01

Nitrite oxidation is an essential step in transformations of fixed nitrogen. The physiology of nitrite oxidizing bacteria (NOB) implies that the rates of nitrite oxidation should be controlled by concentration of their substrate, nitrite, and the terminal electron acceptor, oxygen. The sensitivities of nitrite oxidation to oxygen and nitrite concentrations were investigated using 15N tracer incubations in the Eastern Tropical North Pacific. Nitrite stimulated nitrite oxidation under low in situ nitrite conditions, following Michaelis-Menten kinetics, indicating that nitrite was the limiting substrate. The nitrite half-saturation constant (Ks = 0.254 ± 0.161 μM) was 1-3 orders of magnitude lower than in cultivated NOB, indicating higher affinity of marine NOB for nitrite. The highest rates of nitrite oxidation were measured in the oxygen depleted zone (ODZ), and were partially inhibited by additions of oxygen. This oxygen sensitivity suggests that ODZ specialist NOB, adapted to low-oxygen conditions, are responsible for apparently anaerobic nitrite oxidation.

Patterned Electrode-Based Amperometric Gas Sensor for Direct Nitric Oxide Detection within Microfluidic Devices

PubMed Central

Cha, Wansik; Tung, Yi-Chung; Meyerhoff, Mark E.; Takayama, Shuichi

2010-01-01

This manuscript describes a thin amperometric nitric oxide (NO) sensor that can be microchannel embedded to enable direct real-time detection of NO produced by cells cultured within the microdevice. A key for achieving the thin (~ 1 mm) planar sensor configuration required for sensor-channel integration is the use of gold/indium-tin oxide patterned electrode directly on a porous polymer membrane (pAu/ITO) as the base working electrode. Electrochemically deposited Au-hexacyanoferrate layer on pAu/ITO is used to catalyze NO oxidation to nitrite at lower applied potentials (0.65 ~ 0.75 V vs. Ag/AgCl) and stabilize current output. Furthermore, use of a gas-permeable membrane to separate internal sensor compartments from the sample phase imparts excellent NO selectivity over common interferents (e.g., nitrite, ascorbate, ammonia, etc.) present in culture media and biological fluids. The optimized sensor design reversibly detects NO down to ~1 nM level in stirred buffer and <10 nM in flowing buffer when integrated within a polymeric microfluidic device. We demonstrate utility of the channel-embedded sensor by monitoring NO generation from macrophages cultured within non-gas permeable microchannels, as they are stimulated with endotoxin. PMID:20329749

Coexistence of nitrifying, anammox and denitrifying bacteria in a sequencing batch reactor

PubMed Central

Langone, Michela; Yan, Jia; Haaijer, Suzanne C. M.; Op den Camp, Huub J. M.; Jetten, Mike S. M.; Andreottola, Gianni

2014-01-01

Elevated nitrogen removal efficiencies from ammonium-rich wastewaters have been demonstrated by several applications, that combine nitritation and anammox processes. Denitrification will occur simultaneously when organic carbon is also present. In this study, the activity of aerobic ammonia oxidizing, anammox and denitrifying bacteria in a full scale sequencing batch reactor, treating digester supernatants, was studied by means of batch-assays. AOB and anammox activities were maximum at pH of 8.0 and 7.8–8.0, respectively. Short term effect of nitrite on anammox activity was studied, showing nitrite up to 42 mg/L did not result in inhibition. Both denitrification via nitrate and nitrite were measured. To reduce nitrite-oxidizing activity, high NH3-N (1.9–10 mg NH3-N/L) and low nitrite (3–8 mg TNN/L) are required conditions during the whole SBR cycle. Molecular analysis showed the nitritation-anammox sludge harbored a high microbial diversity, where each microorganism has a specific role. Using ammonia monooxygenase α–subunit (amoA) gene as a marker, our analyses suggested different macro- and micro-environments in the reactor strongly affect the AOB community, allowing the development of different AOB species, such as N. europaea/eutropha and N. oligotropha groups, which improve the stability of nitritation process. A specific PCR primer set, used to target the 16S rRNA gene of anammox bacteria, confirmed the presence of the “Ca. Brocadia fulgida” type, able to grow in presence of organic matter and to tolerate high nitrite concentrations. The diversity of denitrifiers was assessed by using dissimilatory nitrite reductase (nirS) gene-based analyses, who showed denitifiers were related to different betaproteobacterial genera, such as Thauera, Pseudomonas, Dechloromonas and Aromatoleum, able to assist in forming microbial aggregates. Concerning possible secondary processes, no n-damo bacteria were found while NOB from the genus Nitrobacter was detected. PMID:24550899

Understanding Differences in the Nitrogen Cycle in Low-Oxygen Zones in the Eastern Tropical North Pacific

NASA Astrophysics Data System (ADS)

Wood, C.; Travis, N. M.; Forbes, M. S.; Casciotti, K. L.

2016-12-01

Hypoxic and anoxic zones are found in oceans worldwide. These zones can be caused by warm water "caps" that trap colder water underneath the warm water so the cold water cannot replenish its oxygen. Processes such as global warming and eutrophication can also contribute to such oxygen-depleted zones. Thus, it is important to study these zones to investigate and reveal the impact humans have on ecosystems worldwide so we can fix the problems we have caused. The Eastern Tropical North Pacific (ETNP), off the southwestern coast of Mexico, contains a natural-oxygen deficient zone. On a research cruise to the ETNP in April 2016, incubations were conducted to measure the rates of nitrification in the upper water column (upper 100 m) at three stations. Incubations were conducted in light and dark bottles spiked with 15N-containing nitrite. In this study, nitrite concentration in incubation starting points was analyzed. For each point, four depths of increasing depth (they varied depending on the station) were analyzed, and for each depth there were three samples. For each sample five absorbance measurements were averaged to calculate nitrite concentration against known standards. Concentrations of nitrite were found to increase moving into the oxygen deficient zone. The nitrite peaks at the coastal stations were at shallower depths than the peak at the centermost station in the low-oxygen zone. At the centermost station within the oxygen-deficient region, the nitrite concentration at the primary peak was 1.6µM, which was the highest point out of all the stations. This nitrite concentration data will be expanded to all stations where 15N addition incubation experiments were performed. In the future, these time-zero data will be combined with time-24 data to calculate nitrite oxidation rates based on 15N isotope analysis. Measuring nitrite oxidation rates will help us further understand processes structuring nitrite accumulation in the ETNP low-oxygen zone.

Refined NrfA phylogeny improves PCR-based nrfA gene detection

USDA-ARS?s Scientific Manuscript database

Dissimilatory nitrate reduction to ammonium (DNRA) promotes N-retention in the terrestrial nitrogen- (N-) cycle. Respiratory nitrite reduction to ammonium is catalyzed by the nitrite reductase NrfA. Prior phylogenetic analyses showed that NrfA divided into18 distinct clades amongst available sequenc...

Differential Sensitivities of Pulmonary and Coronary Arteries to Hemoglobin-Based Oxygen Carriers and Nitrovasodilators: Study in a Bovine Ex Vivo Model of Vascular Strips

DTIC Science & Technology

2010-01-01

dependent manner, with a relatively high average IC50 of8.5 J.lM (Table 1 ). For bovine pulmonary artery, the JC50 for sodium nitrite was more than 1... dependent on nitrovasodilator concentration, suggesting SNP and sodium nitrite -induced autocatalytic conversion of oxyhemoglobin to methemoglobin at...Gladwin, M.T., Kim-Shapiro, D.R., 2008. The functional nitrite reductase activity of the heme -globins. Blood 112, 2636-2647. Hart, j.L, Ledvina, M.A

Nitrogen removal by recycle water nitritation as an attractive alternative for retrofit technologies in municipal wastewater treatment plants.

PubMed

Gil, K I; Choi, E

2004-01-01

The recycle water from sludge processing in municipal wastewater treatment plants causes many serious problems in the efficiency and stability of the mainstream process. Thus, the design approach for recycle water is an important part of any biological nutrient removal system design when a retrofit technology is required for upgrading an existing plant. Moreover, the application of nitrogen removal from recycle water using the nitritation process has recently increased due to economic reasons associated with an effective carbon allocation as well as the minimization of aeration costs. However, for the actual application of recycle water nitritation, it has not been fully examined whether or not additional volume would be required in an existing plant. In this paper, the addition of recycle water nitritation to an existing plant was evaluated based on a volume analysis and estimation of final effluent quality. It was expected that using the reserve volume of the aeration tank in existing plants, recycle water nitritation could be applied to a plant without any enlargement. With the addition of recycle water nitritation, it was estimated that the final effluent quality would be improved and stabilized, especially in the winter season.

The inhibitory effects of free ammonia on ammonia oxidizing bacteria and nitrite oxidizing bacteria under anaerobic condition.

PubMed

Qian, Wenting; Peng, Yongzhen; Li, Xiyao; Zhang, Qiong; Ma, Bin

2017-11-01

The free ammonia (FA) inhibition on ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) under anaerobic condition was investigated in this study. The results indicated that NOB was more sensitive to the FA anaerobic treatment than AOB. The FA anaerobic inhibition on nitrifier gradually heightened with the increase of FA concentration. Accompanied with FA concentration increase from 0 to 16.82mgNH 3 -N·L -1 (the highest concentration adopted in this study), the activity of AOB reduced by 15.9%, while NOB decreased by 29.2%. After FA anaerobic treatment, nitrite was accumulated during nitrification. However, the nitrite accumulation disappeared on the sixth cycle of activity recovery tests with excessive aeration. Based on this result, a novel strategy for achieving nitritation is proposed, which involves recirculating a portion of the activated sludge through a side-line sludge treatment unit, where the sludge is subjected to treatment with FA under anaerobic condition. Copyright © 2017 Elsevier Ltd. All rights reserved.

A Novel Nanofilm Sensor Based on Poly-(Alizarin Red)/Fe3O4 Magnetic Nanoparticles-Multiwalled Carbon Nanotubes Composite Material for Determination of Nitrite.

PubMed

Qu, Jianying; Dong, Ying; Yong, Wang; Lou, Tongfang; Du, Xueping; Qu, Jianhang

2016-03-01

Fe3O4 magnetic nanoparticles were synthesized by chemical co-precipitation with sodium citrate as surfactant and were characterized by FT-IR spectrometer, X-ray diffraction and transmission electron microscopy. A novel nitrite sensor was fabricated by electropolymerization of alizarin red on the surface of glassy carbon electrode modified with Fe3O4-multiwalled carbon nanotubes composite nanofilm. Under the optimal experimental conditions, it was showed that the proposed sensor exhibited good electrocatalytic activity to the oxidation of nitrite, and the peak current increased linearly with the nitrite concentration from 9.64 x 10(-6) mol x L(-1) to 1.30 x 10(-3) mol x L(-1) (R = 0.9976) with a detection limit of 1.19 x 10(-6) mol x L(-1) (S/N = 3). This sensor showed excellent sensitivity, wide linear range, stability and repeatability for nitrite determination with potential applications.

Amperometric determination of nitrite using natural fibers as template for titanium dioxide nanotubes with immobilized hemin as electron transfer mediator.

PubMed

Ranjani, Balasubramanian; Kalaiyarasi, Jayaprakasham; Pavithra, Loganathan; Devasena, Thiyagarajan; Pandian, Kannaiyan; Gopinath, Subash C B

2018-02-23

A sensing device was constructed for the amperometric determination of nitrite. It is based on the use of titanium dioxide (TiO 2 ) nanotubes template with natural fibers and carrying hemin acting as the electron mediator. A glassy carbon electrode (GCE) was modified with the hemin/TNT nanocomposite. The electrochemical response to nitrite was characterized by impedance spectroscopy and cyclic voltammetry. An amperometric study, performed at a working potential of + 0.75 V (vs. Ag/AgCl), showed the sensor to enable determination of nitrite with a linear response in the 0.6 to 130 μM concentration range and with a 59 nM limit of detection. Corresponding studies by differential study voltammetry (E p  = 0.75 V) exhibited a linear range from 0.6 × 10 -6 to 7.3 × 10 -5  M with a limit of detection of 84 nM. The sensing device was applied to the determination of nitrite in spiked tap and lake water samples. Graphical abstract Natural fibers templated synthesis of TNT immobilized hemin as electron transfer mediator for quantitative detection of nitrite with detection limit of 59 nM and good electrochemical sensitivity and the method can be used for quantitative determination of nitrite in water samples.

Microwave enhanced chemical reduction process for nitrite-containing wastewater treatment using sulfaminic acid.

PubMed

Li, Nan; Wang, Peng; Liu, Qingsong; Cao, Hailei

2010-01-01

High-concentration nitrite-containing wastewater that presents extreme toxicity to human health and organisms is difficult to be treated using traditional biological process. In this study, a novel microwave-enhanced chemical reduction process (MECRP) using sulfaminic acid (SA) was proposed as a new manner to treat such type of wastewater. Based on lab-scale experiments, it was shown that 75%-80% nitrite (NO2-) could be removed within time as short as 4 min under 50 W microwave irradiation in pH range 5-10 when molar ratio of SA to nitrite (SA/NO2-) was 0.8. Pilot-scale investigations demonstrated that MECRP was able to achieve nitrite and chemical oxygen demand (COD) removal with efficiency up to 80% and 20%, respectively under operating conditions of SA concentration 80 kg/m3, SA/NO2- ratio 0.8, microwave power 3.4 kW, and stirring time 3 min. Five-day biological oxygen demand (BOD5)/COD value of treated effluent after MECRP was increased from 0.05 to 0.36 (by 620%), which clearly suggested a considerable improvement of biodegradability for subsequent biological treatment. This study provided a demonstration of using microwave irradiation to enhance reaction between SA and nitrite in a short time, in which nitrite in wastewater was completely converted into nitrogen gas without leaving any sludge and secondary pollutants.

21 CFR 181.34 - Sodium nitrite and potassium nitrite.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Sodium nitrite and potassium nitrite. 181.34...-Sanctioned Food Ingredients § 181.34 Sodium nitrite and potassium nitrite. Sodium nitrite and potassium nitrite are subject to prior sanctions issued by the U.S. Department of Agriculture for use as color...

21 CFR 181.34 - Sodium nitrite and potassium nitrite.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Sodium nitrite and potassium nitrite. 181.34...-Sanctioned Food Ingredients § 181.34 Sodium nitrite and potassium nitrite. Sodium nitrite and potassium nitrite are subject to prior sanctions issued by the U.S. Department of Agriculture for use as color...

21 CFR 181.34 - Sodium nitrite and potassium nitrite.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Sodium nitrite and potassium nitrite. 181.34... nitrite and potassium nitrite. Sodium nitrite and potassium nitrite are subject to prior sanctions issued... without sodium or potassium nitrate, in the curing of red meat and poultry products. [48 FR 1705, Jan. 14...

Blood plasma response and urinary excretion of nitrite and nitrate in milk-fed calves after oral nitrite and nitrate administration.

PubMed

Hüsler, B R.; Blum, J W.

2001-05-01

There is marked endogenous production of nitrate in young calves. Here we have studied the contribution of exogenous nitrate and nitrite to plasma concentrations and urinary excretion of nitrite and nitrate in milk-fed calves. In experiment 1, calves were fed 0 or 200 &mgr;mol nitrate or nitrite/kg(0.75) or 100 &mgr;mol nitrite plus 100 &mgr;mol nitrate/kg(0.75) with milk for 3 d. In experiment 2, calves were fed 400 &mgr;mol nitrate or nitrite/kg(0.75) with milk for 1 d. Plasma nitrate rapidly and comparably increased after feeding nitrite, nitrate or nitrite plus nitrate. The rise of plasma nitrate was greater if 400 than 200 &mgr;mol nitrate or nitrite/kg(0.75) were fed. Plasma nitrate decreased slowly after the 3-d administration of 200 &mgr;mol nitrate or nitrite/kg(0.75) and reached pre-experimental concentrations 4 d later. Urinary nitrate excretions nearly identically increased if nitrate, nitrite or nitrite plus nitrate were administered and excreted amounts were greater if 400 than 200 &mgr;mol nitrate or nitrite/kg(0.75) were fed. After nitrite ingestion plasma nitrite only transiently increased after 2 and 4 h and urinary excretion rates remained unchanged. Plasma nitrate concentration remained unchanged if milk was not supplemented with nitrite or nitrate. Nitrate concentrations were stable for 24 h after addition of nitrite to full blood in vitro, whereas nitrite concentrations decreased within 2 h. In conclusion, plasma nitrate concentrations and urinary nitrate excretions are enhanced dose-dependently by feeding low amounts of nitrate and nitrite, whereas after ingested nitrite only a transient and small rise of plasma nitrite is observed because of rapid conversion to nitrate.

Evaluation of nitrate and nitrite contents in pickled fruit and vegetable products

USDA-ARS?s Scientific Manuscript database

Our objective was to investigate nitrate and nitrite contents of acidified and fermented fruits and vegetables. L-ascorbic acid and total phenols were also examined based on the hypothesis that the presence of these antioxidant compounds may influence N-nitrosation reactions upon human consumption. ...

Nitrite reduction mechanism on a Pd surface.

PubMed

Shin, Hyeyoung; Jung, Sungyoon; Bae, Sungjun; Lee, Woojin; Kim, Hyungjun

2014-11-04

Nitrate (NO3-) is one of the most harmful contaminants in the groundwater, and it causes various health problems. Bimetallic catalysts, usually palladium (Pd) coupled with secondary metallic catalyst, are found to properly treat nitrate-containing wastewaters; however, the selectivity toward N2 production over ammonia (NH3) production still requires further improvement. Because the N2 selectivity is determined at the nitrite (NO2-) reduction step on the Pd surface, which occurs after NO3- is decomposed into NO2- on the secondary metallic catalyst, we here performed density functional theory (DFT) calculations and experiments to investigate the NO2- reduction pathway on the Pd surface activated by hydrogen. Based on extensive DFT calculations on the relative energetics among ∼100 possible intermediates, we found that NO2- is easily reduced to NO* on the Pd surface, followed by either sequential hydrogenation steps to yield NH3 or a decomposition step to N* and O* (an adsorbate on Pd is denoted using an asterisk). Based on the calculated high migration barrier of N*, we further discussed that the direct combination of two N* to yield N2 is kinetically less favorable than the combination of a highly mobile H* with N* to yield NH3. Instead, the reduction of NO2- in the vicinity of the N* can yield N2O* that can be preferentially transformed into N2 via diverse reaction pathways. Our DFT results suggest that enhancing the likelihood of N* encountering NO2- in the solution phase before combination with surface H* is important for maximizing the N2 selectivity. This is further supported by our experiments on NO2- reduction by Pd/TiO2, showing that both a decreased H2 flow rate and an increased NO2- concentration increased the N2 selectivity (78.6-93.6% and 57.8-90.9%, respectively).

Effects of Bacterial Community Members on the Proteome of the Ammonia-Oxidizing Bacterium Nitrosomonas sp. Strain Is79.

PubMed

Sedlacek, Christopher J; Nielsen, Susanne; Greis, Kenneth D; Haffey, Wendy D; Revsbech, Niels Peter; Ticak, Tomislav; Laanbroek, Hendrikus J; Bollmann, Annette

2016-08-01

Microorganisms in the environment do not exist as the often-studied pure cultures but as members of complex microbial communities. Characterizing the interactions within microbial communities is essential to understand their function in both natural and engineered environments. In this study, we investigated how the presence of a nitrite-oxidizing bacterium (NOB) and heterotrophic bacteria affect the growth and proteome of the chemolithoautotrophic ammonia-oxidizing bacterium (AOB) Nitrosomonas sp. strain Is79. We investigated Nitrosomonas sp. Is79 in co-culture with Nitrobacter winogradskyi, in co-cultures with selected heterotrophic bacteria, and as a member of the nitrifying enrichment culture G5-7. In batch culture, N. winogradskyi and heterotrophic bacteria had positive effects on the growth of Nitrosomonas sp. Is79. An isobaric tag for relative and absolute quantification (iTRAQ) liquid chromatography-tandem mass spectrometry (LC-MS/MS) proteomics approach was used to investigate the effect of N. winogradskyi and the co-cultured heterotrophic bacteria from G5-7 on the proteome of Nitrosomonas sp. Is79. In co-culture with N. winogradskyi, several Nitrosomonas sp. Is79 oxidative stress response proteins changed in abundance, with periplasmic proteins increasing and cytoplasmic proteins decreasing in abundance. In the presence of heterotrophic bacteria, the abundance of proteins directly related to the ammonia oxidation pathway increased, while the abundance of proteins related to amino acid synthesis and metabolism decreased. In summary, the proteome of Nitrosomonas sp. Is79 was differentially influenced by the presence of either N. winogradskyi or heterotrophic bacteria. Together, N. winogradskyi and heterotrophic bacteria reduced the oxidative stress for Nitrosomonas sp. Is79, which resulted in more efficient metabolism. Aerobic ammonia-oxidizing microorganisms play an important role in the global nitrogen cycle, converting ammonia to nitrite. In their natural environment, they coexist and interact with nitrite oxidizers, which convert nitrite to nitrate, and with heterotrophic microorganisms. The presence of nitrite oxidizers and heterotrophic bacteria has a positive influence on the growth of the ammonia oxidizers. Here, we present a study investigating the effect of nitrite oxidizers and heterotrophic bacteria on the proteome of a selected ammonia oxidizer in a defined culture to elucidate how these two groups improve the performance of the ammonia oxidizer. The results show that the presence of a nitrite oxidizer and heterotrophic bacteria reduced the stress for the ammonia oxidizer and resulted in more efficient energy generation. This study contributes to our understanding of microbe-microbe interactions, in particular between ammonia oxidizers and their neighboring microbial community. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Dietary nitrate and nitrite modulate blood and organ nitrite and the cellular ischemic stress response

PubMed Central

Raat, Nicolaas J.H.; Noguchi, Audrey C.; Liu, Virginia B.; Raghavachari, Nalini; Liu, Delong; Xu, Xiuli; Shiva, Sruti; Munson, Peter J.; Gladwin, Mark T.

2009-01-01

Dietary nitrate, found in abundance in green vegetables, can be converted to the cytoprotective molecule nitrite by oral bacteria, suggesting that nitrate and nitrite may represent active cardioprotective constituents of the Mediterranean diet. We therefore tested the hypothesis that dietary nitrate and nitrite levels modulate tissue damage and ischemic gene expression in a mouse liver ischemia-reperfusion model. We found that stomach content, plasma, heart and liver nitrite levels were significantly reduced after dietary nitrate and nitrite depletion, and could be restored to normal levels with nitrite supplementation in water. Remarkably, we confirmed that basal nitrite levels significantly reduced liver injury after ischemia-reperfusion. Consistent with an effect of nitrite on the post-translational modification of complex I of the mitochondrial electron transport chain, the severity of liver infarction was inversely proportional to complex I activity after nitrite repletion in the diet. The transcriptional response of dietary nitrite after ischemia was more robust than after normoxia, suggesting a hypoxic potentiation of nitrite-dependent transcriptional signaling. Our studies indicate that normal dietary nitrate and nitrite levels modulate ischemic stress responses and hypoxic gene expression programs, supporting the hypothesis that dietary nitrate and nitrite are cytoprotective components of the diet. PMID:19464364

21 CFR 181.34 - Sodium nitrite and potassium nitrite.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Sodium nitrite and potassium nitrite. 181.34...-Sanctioned Food Ingredients § 181.34 Sodium nitrite and potassium nitrite. Sodium nitrite and potassium... fixatives and preservative agents, with or without sodium or potassium nitrate, in the curing of red meat...

21 CFR 181.34 - Sodium nitrite and potassium nitrite.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Sodium nitrite and potassium nitrite. 181.34...-Sanctioned Food Ingredients § 181.34 Sodium nitrite and potassium nitrite. Sodium nitrite and potassium... fixatives and preservative agents, with or without sodium or potassium nitrate, in the curing of red meat...

Stable performance of non‐aerated two‐stage partial nitritation/anammox (PANAM) with minimal process control

PubMed Central

Bagchi, Samik; Biswas, Rima; Vlaeminck, Siegfried E.; Roychoudhury, Kunal; Nandy, Tapas

2012-01-01

Summary Partial nitritation/anammox (PANAM) technologies have rapidly developed over the last decade, but still considerable amounts of energy are required for active aeration. In this study, a non‐aerated two‐stage PANAM process was investigated. In the first‐stage upflow fixed‐film bioreactor, nitratation could not be prevented at ammonium loading rates up to 186 mg N l−1 d−1 and low influent dissolved oxygen (0.1 mg O2 l−1). Yet, increasing the loading rate to 416 and 747 mg N l−1 d−1 by decreasing the hydraulic retention time to 8 and 5 h, respectively, resulted in partial nitritation with the desired nitrite to ammonium nitrogen ratio for the subsequent anammox stage (0.71–1.05). The second‐stage anammox reactor was established with a synthetic feeding based on ammonium and nitrite. After establishing anammox at low biomass content (0.5 g VSS l−1), the anammox influent was switched to partial nitritation effluent at a loading rate of 71 mg N l−1 d−1, of which 78% was removed at the stoichiometrically expected nitrite to ammonium consumption ratios (1.19) and nitrate production to ammonium consumption ratio (0.24). The combined PANAM reactors were operated for 3 months at a stable performance. Overall, PANAM appeals economically, saving about 50% of the energy costs, as well as technically, given straightforward operational principles. PMID:22414169

Elucidating the mechanism for the reduction of nitrite by copper nitrite reductase--a contribution from quantum chemical studies.

PubMed

De Marothy, S A; Blomberg, M R A; Siegbahn, P E M

2007-01-30

Density functional methods have been applied to investigate the properties of the active site of copper-containing nitrite reductases and possible reaction mechanisms for the enzyme catalysis. The results for a model of the active site indicate that a hydroxyl intermediate is not formed during the catalytic cycle, but rather a state with a protonated nitrite bound to the reduced copper. Electron affinity calculations indicate that reduction of the T2 copper site does not occur immediately after nitrite binding. Proton affinity calculations are indicative of substantial pK(a) differences between different states of the T2 site. The calculations further suggest that the reaction does not proceed until uptake of a second proton from the bulk solution. They also indicate that Asp-92 may play both a key role as a proton donor to the substrate, and a structural role in promoting catalysis. In the D92N mutant another base, presumably a nearby histidine (His-249) may take the role as the proton donor. On the basis of these model calculations and available experimental evidence, an ordered reaction mechanism for the reduction of nitrite is suggested. An investigation of the binding modes of the nitric oxide product and the nitrite substrate to the model site has also been made, indicating that nitric oxide prefers to bind in an end-on fashion to the reduced T2 site.

Dietary intake of polyphenols, nitrate and nitrite and gastric cancer risk in Mexico City

PubMed Central

Hernández-Ramírez, Raúl U.; Galván-Portillo, Marcia V.; Ward, Mary H.; Agudo, Antonio; González, Carlos A.; Oñate-Ocaña, Luis F.; Herrera-Goepfert, Roberto; Palma-Coca, Oswaldo; López-Carrillo, Lizbeth

2009-01-01

N-Nitroso compounds (NOC) are potent animal carcinogens and potential human carcinogens. The primary source of exposure for most individuals may be endogenous formation, a process that can be inhibited by dietary polyphenols. To estimate the risk of gastric cancer (GC) in relation to the individual and combined consumption of polyphenols and NOC precursors (nitrate and nitrite), a population-based case–control study was carried out in Mexico City from 2004 to 2005 including 257 histologically confirmed GC cases and 478 controls. Intake of polyphenols, nitrate and nitrite were estimated using a food frequency questionnaire. High intakes of cinnamic acids, secoisolariciresinol and coumestrol were associated with an ~50% reduction in GC risk. A high intake of total nitrite as well as nitrate and nitrite from animal sources doubled the GC risk. Odds ratios around 2-fold were observed among individuals with both low intake of cinnamic acids, secoisolariciresinol or coumestrol and high intake of animal-derived nitrate or nitrite, compared to high intake of the polyphenols and low animal nitrate or nitrite intake, respectively. Results were similar for both the intestinal and diffuse types of GC. Our results show, for the first time, a protective effect for GC because of higher intake of cinnamic acids, secoisolariciresinol and coumestrol, and suggest that these polyphenols reduce GC risk through inhibition of endogenous nitrosation. The main sources of these polyphenols were pears, mangos and beans for cinnamic acids; beans, carrots and squash for secoisolariciresinol and legumes for coumestrol. PMID:19449378

Expanded metabolic versatility of ubiquitous nitrite-oxidizing bacteria from the genus Nitrospira.

PubMed

Koch, Hanna; Lücker, Sebastian; Albertsen, Mads; Kitzinger, Katharina; Herbold, Craig; Spieck, Eva; Nielsen, Per Halkjaer; Wagner, Michael; Daims, Holger

2015-09-08

Nitrospira are a diverse group of nitrite-oxidizing bacteria and among the environmentally most widespread nitrifiers. However, they remain scarcely studied and mostly uncultured. Based on genomic and experimental data from Nitrospira moscoviensis representing the ubiquitous Nitrospira lineage II, we identified ecophysiological traits that contribute to the ecological success of Nitrospira. Unexpectedly, N. moscoviensis possesses genes coding for a urease and cleaves urea to ammonia and CO2. Ureolysis was not observed yet in nitrite oxidizers and enables N. moscoviensis to supply ammonia oxidizers lacking urease with ammonia from urea, which is fully nitrified by this consortium through reciprocal feeding. The presence of highly similar urease genes in Nitrospira lenta from activated sludge, in metagenomes from soils and freshwater habitats, and of other ureases in marine nitrite oxidizers, suggests a wide distribution of this extended interaction between ammonia and nitrite oxidizers, which enables nitrite-oxidizing bacteria to indirectly use urea as a source of energy. A soluble formate dehydrogenase lends additional ecophysiological flexibility and allows N. moscoviensis to use formate, with or without concomitant nitrite oxidation, using oxygen, nitrate, or both compounds as terminal electron acceptors. Compared with Nitrospira defluvii from lineage I, N. moscoviensis shares the Nitrospira core metabolism but shows substantial genomic dissimilarity including genes for adaptations to elevated oxygen concentrations. Reciprocal feeding and metabolic versatility, including the participation in different nitrogen cycling processes, likely are key factors for the niche partitioning, the ubiquity, and the high diversity of Nitrospira in natural and engineered ecosystems.

Long-term dietary nitrite and nitrate deficiency causes the metabolic syndrome, endothelial dysfunction and cardiovascular death in mice.

PubMed

Kina-Tanada, Mika; Sakanashi, Mayuko; Tanimoto, Akihide; Kaname, Tadashi; Matsuzaki, Toshihiro; Noguchi, Katsuhiko; Uchida, Taro; Nakasone, Junko; Kozuka, Chisayo; Ishida, Masayoshi; Kubota, Haruaki; Taira, Yuji; Totsuka, Yuichi; Kina, Shin-Ichiro; Sunakawa, Hajime; Omura, Junichi; Satoh, Kimio; Shimokawa, Hiroaki; Yanagihara, Nobuyuki; Maeda, Shiro; Ohya, Yusuke; Matsushita, Masayuki; Masuzaki, Hiroaki; Arasaki, Akira; Tsutsui, Masato

2017-06-01

Nitric oxide (NO) is synthesised not only from L-arginine by NO synthases (NOSs), but also from its inert metabolites, nitrite and nitrate. Green leafy vegetables are abundant in nitrate, but whether or not a deficiency in dietary nitrite/nitrate spontaneously causes disease remains to be clarified. In this study, we tested our hypothesis that long-term dietary nitrite/nitrate deficiency would induce the metabolic syndrome in mice. To this end, we prepared a low-nitrite/nitrate diet (LND) consisting of an amino acid-based low-nitrite/nitrate chow, in which the contents of L-arginine, fat, carbohydrates, protein and energy were identical with a regular chow, and potable ultrapure water. Nitrite and nitrate were undetectable in both the chow and the water. Three months of the LND did not affect food or water intake in wild-type C57BL/6J mice compared with a regular diet (RD). However, in comparison with the RD, 3 months of the LND significantly elicited visceral adiposity, dyslipidaemia and glucose intolerance. Eighteen months of the LND significantly provoked increased body weight, hypertension, insulin resistance and impaired endothelium-dependent relaxations to acetylcholine, while 22 months of the LND significantly led to death mainly due to cardiovascular disease, including acute myocardial infarction. These abnormalities were reversed by simultaneous treatment with sodium nitrate, and were significantly associated with endothelial NOS downregulation, adiponectin insufficiency and dysbiosis of the gut microbiota. These results provide the first evidence that long-term dietary nitrite/nitrate deficiency gives rise to the metabolic syndrome, endothelial dysfunction and cardiovascular death in mice, indicating a novel pathogenetic role of the exogenous NO production system in the metabolic syndrome and its vascular complications.

Effect of curing agents on the oxidative and nitrosative damage to meat proteins during processing of fermented sausages.

PubMed

Villaverde, A; Morcuende, D; Estévez, M

2014-07-01

The effect of increasing concentrations of curing agents, ascorbate (0, 250, and 500 ppm), and nitrite (0, 75, and 150 ppm), on the oxidative and nitrosative damage to proteins during processing of fermented sausages was studied. The potential influence of these reactions on color and texture of the fermented sausages was also addressed. Nitrite had a pro-oxidant effect on tryptophan depletion and promoted the formation of protein carbonyls and Schiff bases. The nitration degree in the fermented sausages was also dependent on nitrite concentration. On the other hand, ascorbate acted as an efficient inhibitor of the oxidative and nitrosative damage to meat proteins. As expected, nitrite clearly favored the formation of the cured red color and ascorbate acted as an enhancer of color formation. Nitrite content was positively correlated with hardness. The chemistry behind the action of nitrite and ascorbate on muscle proteins during meat fermentation is thoroughly discussed. The results suggest that ascorbate (500 ppm) may be required to compensate the pro-oxidant impact of nitrite on meat proteins. This study provides insight on the action of curing agents on meat proteins during processing of fermented sausages. This chemistry background provides understanding of the potential influence of the oxidative and nitrosative damage to proteins on the quality of processed muscle foods. The study provides novel information on the impact of the combination of nitrite and ascorbate on the chemical deterioration of proteins and the influence on particular quality traits of fermented sausages. These data may be of interest for the design of cured muscle foods of enhanced quality. © 2014 Institute of Food Technologists®

Oxygen isotopes in nitrite: Analysis, calibration, and equilibration

USGS Publications Warehouse

Casciotti, K.L.; Böhlke, J.K.; McIlvin, M.R.; Mroczkowski, S.J.; Hannon, J.E.

2007-01-01

Nitrite is a central intermediate in the nitrogen cycle and can persist in significant concentrations in ocean waters, sediment pore waters, and terrestrial groundwaters. To fully interpret the effect of microbial processes on nitrate (NO3-), nitrite (NO2-), and nitrous oxide (N2O) cycling in these systems, the nitrite pool must be accessible to isotopic analysis. Furthermore, because nitrite interferes with most methods of nitrate isotopic analysis, accurate isotopic analysis of nitrite is essential for correct measurement of nitrate isotopes in a sample that contains nitrite. In this study, nitrite salts with varying oxygen isotopic compositions were prepared and calibrated and then used to test the denitrifier method for nitrite oxygen isotopic analysis. The oxygen isotopic fractionation during nitrite reduction to N2O by Pseudomonas aureofaciens was lower than for nitrate conversion to N2O, while oxygen isotopic exchange between nitrite and water during the reaction was similar. These results enable the extension of the denitrifier method to oxygen isotopic analysis of nitrite (in the absence of nitrate) and correction of nitrate isotopes for the presence of nitrite in “mixed” samples. We tested storage conditions for seawater and freshwater samples that contain nitrite and provide recommendations for accurate oxygen isotopic analysis of nitrite by any method. Finally, we report preliminary results on the equilibrium isotope effect between nitrite and water, which can play an important role in determining the oxygen isotopic value of nitrite where equilibration with water is significant.

FIA-automated system used to electrochemically measure nitrite and its interfering chemicals through a 1-2 DAB / Au electrode: gain of sensitivity at upper potentials

NASA Astrophysics Data System (ADS)

Almeida, F. L.; dos Santos Filho, S. G.; Fontes, M. B. A.

2013-03-01

The measurement of nitrite and its interfering-chemicals (paracetamol, ascorbic acid and uric acid) was performed employing a Flow-injection Analysis (FIA) system, which was automated using solenoid valves and air-pump. It is very important to quantify nitrite from river water, food and biologic fluids due to its antibacterial capacity in moderated concentrations, or its toxicity for human health even at low concentrations (> 20 μmol L-1 in blood fluids). Electrodes of the electrochemical planar sensor were defined by silk-screen technology. The measuring electrode was made from gold paste covered with 1-2 cis Diaminobenzene (DAB), which allowed good selectivity, linearity, repeatability, stability and optimized gain of sensitivity at 0.5 VAg/AgCl Nafion®117 (6.93 μA mol-1 L mm-2) compared to 0.3 VAg/AgCl Nafion® 117. The reference electrode was obtained from silver/palladium paste modified with chloride and covered with Nafion® 117. The auxiliary electrode was made from platinum paste. It was noteworthy that nitrite response adds to the response of the studied interfering-chemicals and it is predominant for concentrations lower than 175 μmol L-1.

Advances in methods for detection of anaerobic ammonium oxidizing (anammox) bacteria.

PubMed

Li, Meng; Gu, Ji-Dong

2011-05-01

Anaerobic ammonium oxidation (anammox), the biochemical process oxidizing ammonium into dinitrogen gas using nitrite as an electron acceptor, has only been recognized for its significant role in the global nitrogen cycle not long ago, and its ubiquitous distribution in a wide range of environments has changed our knowledge about the contributors to the global nitrogen cycle. Currently, several groups of methods are used in detection of anammox bacteria based on their physiological and biochemical characteristics, cellular chemical composition, and both 16S rRNA gene and selective functional genes as biomarkers, including hydrazine oxidoreductase and nitrite reductase encoding genes hzo and nirS, respectively. Results from these methods coupling with advances in quantitative PCR, reverse transcription of mRNA genes and stable isotope labeling have improved our understanding on the distribution, diversity, and activity of anammox bacteria in different environments both natural and engineered ones. In this review, we summarize these methods used in detection of anammox bacteria from various environments, highlight the strengths and weakness of these methods, and also discuss the new development potentials on the existing and new techniques in the future.

Prospective study of meat intake and dietary nitrates, nitrites, and nitrosamines and risk of adult glioma.

PubMed

Michaud, Dominique S; Holick, Crystal N; Batchelor, Tracy T; Giovannucci, Edward; Hunter, David J

2009-09-01

The hypothesis that nitrosamine exposure may increase the risk of glioma has been circulating for several decades, but testing it has been difficult because of the ubiquitous nature of nitrosamine exposure. Diet has been the focus of many studies because it can substantially influence nitrosamine exposure, mostly from the endogenous formation of nitrosamines based on intake of nitrite and nitrate. The objective was to examine the relation between intakes of meats, nitrate, nitrite, and 2 nitrosamines [nitrosodimethylamine (NDMA) and nitrosopyrolidine (NPYR)] and glioma risk in a prospective analysis. Data from 3 US prospective cohort studies were combined for this analysis; 335 glioma cases were diagnosed during < or =24 y of follow-up. Dietary intake was assessed with food-frequency questionnaires. Nitrate, nitrite, and nitrosamine values were calculated based on published values of these nutrients in various foods over different periods in time. Cox proportional hazards models were used to estimate incidence rate ratios (RRs) and 95% CIs. Estimates from each cohort were pooled by using a random-effects model. Risk of glioma was not elevated among individuals in the highest intake category of total processed meats (RR: 0.92; 95% CI: 0.48, 1.77), nitrate (RR: 1.02; 95% CI: 0.66, 1.58), nitrites (RR: 1.26; 95% CI: 0.89, 1.79), or NDMA (RR: 0.88; 95% CI: 0.57, 1.36) compared with the lowest category. No effect modification was observed by intake of vitamins C or E or other antioxidant measures. We found no suggestion that intake of meat, nitrate, nitrite, or nitrosamines is related to the risk of glioma.

Prospective study of meat intake and dietary nitrates, nitrites, and nitrosamines and risk of adult glioma123

PubMed Central

Holick, Crystal N; Batchelor, Tracy T; Giovannucci, Edward; Hunter, David J

2009-01-01

Background: The hypothesis that nitrosamine exposure may increase the risk of glioma has been circulating for several decades, but testing it has been difficult because of the ubiquitous nature of nitrosamine exposure. Diet has been the focus of many studies because it can substantially influence nitrosamine exposure, mostly from the endogenous formation of nitrosamines based on intake of nitrite and nitrate. Objective: The objective was to examine the relation between intakes of meats, nitrate, nitrite, and 2 nitrosamines [nitrosodimethylamine (NDMA) and nitrosopyrolidine (NPYR)] and glioma risk in a prospective analysis. Methods: Data from 3 US prospective cohort studies were combined for this analysis; 335 glioma cases were diagnosed during ≤24 y of follow-up. Dietary intake was assessed with food-frequency questionnaires. Nitrate, nitrite, and nitrosamine values were calculated based on published values of these nutrients in various foods over different periods in time. Cox proportional hazards models were used to estimate incidence rate ratios (RRs) and 95% CIs. Estimates from each cohort were pooled by using a random-effects model. Results: Risk of glioma was not elevated among individuals in the highest intake category of total processed meats (RR: 0.92; 95% CI: 0.48, 1.77), nitrate (RR: 1.02; 95% CI: 0.66, 1.58), nitrites (RR: 1.26; 95% CI: 0.89, 1.79), or NDMA (RR: 0.88; 95% CI: 0.57, 1.36) compared with the lowest category. No effect modification was observed by intake of vitamins C or E or other antioxidant measures. Conclusion: We found no suggestion that intake of meat, nitrate, nitrite, or nitrosamines is related to the risk of glioma. PMID:19587083

A novel marine nitrite-oxidizing Nitrospira species from Dutch coastal North Sea water

PubMed Central

Haaijer, Suzanne C. M.; Ji, Ke; van Niftrik, Laura; Hoischen, Alexander; Speth, Daan; Jetten, Mike S. M.; Damsté, Jaap S. Sinninghe; Op den Camp, Huub J. M.

2013-01-01

Marine microorganisms are important for the global nitrogen cycle, but marine nitrifiers, especially aerobic nitrite oxidizers, remain largely unexplored. To increase the number of cultured representatives of marine nitrite-oxidizing bacteria (NOB), a bioreactor cultivation approach was adopted to first enrich nitrifiers and ultimately nitrite oxidizers from Dutch coastal North Sea water. With solely ammonia as the substrate an active nitrifying community consisting of novel marine Nitrosomonas aerobic ammonia oxidizers (ammonia-oxidizing bacteria) and Nitrospina and Nitrospira NOB was obtained which converted a maximum of 2 mmol of ammonia per liter per day. Switching the feed of the culture to nitrite as a sole substrate resulted in a Nitrospira NOB dominated community (approximately 80% of the total microbial community based on fluorescence in situ hybridization and metagenomic data) converting a maximum of 3 mmol of nitrite per liter per day. Phylogenetic analyses based on the 16S rRNA gene indicated that the Nitrospira enriched from the North Sea is a novel Nitrospira species with Nitrospira marina as the next taxonomically described relative (94% 16S rRNA sequence identity). Transmission electron microscopy analysis revealed a cell plan typical for Nitrospira species. The cytoplasm contained electron light particles that might represent glycogen storage. A large periplasmic space was present which was filled with electron dense particles. Nitrospira-targeted polymerase chain reaction analyses demonstrated the presence of the enriched Nitrospira species in a time series of North Sea genomic DNA samples. The availability of this new Nitrospira species enrichment culture facilitates further in-depth studies such as determination of physiological constraints, and comparison to other NOB species. PMID:23515432

Boletus edulis Nitrite Reductase Reduces Nitrite Content of Pickles and Mitigates Intoxication in Nitrite-intoxicated Mice

PubMed Central

Zhang, Weiwei; Tian, Guoting; Feng, Shanshan; Wong, Jack Ho; Zhao, Yongchang; Chen, Xiao; Wang, Hexiang; Ng, Tzi Bun

2015-01-01

Pickles are popular in China and exhibits health-promoting effects. However, nitrite produced during fermentation adversely affects health due to formation of methemoglobin and conversion to carcinogenic nitrosamine. Fruiting bodies of the mushroom Boletus edulis were capable of inhibiting nitrite production during pickle fermentation. A 90-kDa nitrite reductase (NiR), demonstrating peptide sequence homology to fungal nitrite reductase, was isolated from B. edulis fruiting bodies. The optimum temperature and pH of the enzyme was 45 °C and 6.8, respectively. B. edulis NiR was capable of prolonging the lifespan of nitrite-intoxicated mice, indicating that it had the action of an antidote. The enzyme could also eliminate nitrite from blood after intragastric administration of sodium nitrite, and after packaging into capsule, this nitrite-eliminating activity could persist for at least 120 minutes thus avoiding immediate gastric degradation. B. edulis NiR represents the first nitrite reductase purified from mushrooms and may facilitate subsequent applications. PMID:26446494

Boletus edulis Nitrite Reductase Reduces Nitrite Content of Pickles and Mitigates Intoxication in Nitrite-intoxicated Mice.

PubMed

Zhang, Weiwei; Tian, Guoting; Feng, Shanshan; Wong, Jack Ho; Zhao, Yongchang; Chen, Xiao; Wang, Hexiang; Ng, Tzi Bun

2015-10-08

Pickles are popular in China and exhibits health-promoting effects. However, nitrite produced during fermentation adversely affects health due to formation of methemoglobin and conversion to carcinogenic nitrosamine. Fruiting bodies of the mushroom Boletus edulis were capable of inhibiting nitrite production during pickle fermentation. A 90-kDa nitrite reductase (NiR), demonstrating peptide sequence homology to fungal nitrite reductase, was isolated from B. edulis fruiting bodies. The optimum temperature and pH of the enzyme was 45 °C and 6.8, respectively. B. edulis NiR was capable of prolonging the lifespan of nitrite-intoxicated mice, indicating that it had the action of an antidote. The enzyme could also eliminate nitrite from blood after intragastric administration of sodium nitrite, and after packaging into capsule, this nitrite-eliminating activity could persist for at least 120 minutes thus avoiding immediate gastric degradation. B. edulis NiR represents the first nitrite reductase purified from mushrooms and may facilitate subsequent applications.

Serum nitrate/nitrite concentration correlates with gastric juice nitrate/nitrite: a possible marker for mutagenesis of the proximal stomach.

PubMed

Kishikawa, Hiroshi; Nishida, Jiro; Ichikawa, Hitoshi; Kaida, Shogo; Matsukubo, Takashi; Miura, Soichiro; Morishita, Tetsuo; Hibi, Toshifumi

2011-01-01

In the normal acid-secreting stomach, luminally generated nitric oxide, which contributes to carcinogenesis in the proximal stomach, is associated with the concentration of nitrate plus nitrite (nitrate/nitrite) in gastric juice. We investigated whether the serum nitrate/nitrite concentration is associated with that of gastric juice and whether it can be used as a serum marker. Serum and gastric juice nitrate/nitrite concentration, Helicobacter pylori antibody, and gastric pH were measured in 176 patients undergoing upper endoscopy. Multiple regression analysis revealed that serum nitrate/nitrite concentration was the best independent predictor of gastric juice nitrate/nitrite concentration. On single regression analysis, serum and gastric juice nitrate/nitrite concentration were significantly correlated, according to the following equation: gastric juice nitrate/nitrite concentration (μmol/l) = 3.93 - 0.54 × serum nitrate/nitrite concentration (μmol/l; correlation coefficient = 0.429, p < 0.001). In analyses confined to subjects with gastric pH less than 2.0, and in those with serum markers suggesting normal acid secretion (pepsinogen-I >30 ng/ml and negative H. pylori antibody), the serum nitrate/nitrite concentration was an independent predictor of the gastric juice nitrate/nitrite concentration (p < 0.001). Measuring the serum nitrate/nitrite concentration has potential in estimating the gastric juice nitrate/nitrite concentration. The serum nitrate/nitrite concentration could be useful as a marker for mutagenesis in the proximal stomach. Copyright © 2011 S. Karger AG, Basel.

[Evaluation of the methods for the determination of nitrites in baby foods according Mexican legislation].

PubMed

Morales Guerrero, Josefina C; García Zepeda, Rodrigo A; Flores Ruvalcaba, Edgar; Martínez Michel, Lorelei

2012-09-01

We evaluated the two methods accepted by the Mexican norm for the determination of nitritesin infant meat-based food with vegetables. We determined the content of nitrites in the infant food, raw materials as well as products from the intermediate stages of production. A reagent blank and a reference sample were included at each analytical run. In addition, we determined the sensitivity, recovery percentage and accuracy of each methodology. Infant food results indicated an important difference in the nitrite content determined under each methodology, due to the persistent presence of turbidity in the extracts. Different treatments were proposed to eliminate the turbidity, but these only managed to reduce it. The turbidity was attributed to carbohydrates which disclosed concentration exhibit a wide dispersion and were below the quantifiable limit under both methodologies; therefore it is not recommended to apply these techniques with food suspected to contain traces of nitrites.

Adaptability as the key to success for the ubiquitous marine nitrite oxidizer Nitrococcus

PubMed Central

Füssel, Jessika; Lücker, Sebastian; Yilmaz, Pelin; Nowka, Boris; van Kessel, Maartje A. H. J.; Bourceau, Patric; Hach, Philipp F.; Littmann, Sten; Berg, Jasmine; Spieck, Eva; Daims, Holger; Kuypers, Marcel M. M.; Lam, Phyllis

2017-01-01

Nitrite-oxidizing bacteria (NOB) have conventionally been regarded as a highly specialized functional group responsible for the production of nitrate in the environment. However, recent culture-based studies suggest that they have the capacity to lead alternative lifestyles, but direct environmental evidence for the contribution of marine nitrite oxidizers to other processes has been lacking to date. We report on the alternative biogeochemical functions, worldwide distribution, and sometimes high abundance of the marine NOB Nitrococcus. These largely overlooked bacteria are capable of not only oxidizing nitrite but also reducing nitrate and producing nitrous oxide, an ozone-depleting agent and greenhouse gas. Furthermore, Nitrococcus can aerobically oxidize sulfide, thereby also engaging in the sulfur cycle. In the currently fast-changing global oceans, these findings highlight the potential functional switches these ubiquitous bacteria can perform in various biogeochemical cycles, each with distinct or even contrasting consequences. PMID:29109973

Chloride inhibition of nitrite uptake for non-teleost Actinopterygiian fishes.

PubMed

Boudreaux, Perry J; Ferrara, Allyse M; Fontenot, Quenton C

2007-06-01

Fish that transport environmental chloride with a gill uptake mechanism (gill epithelial Cl(-)/HCO(3)(-)cotransport exchange system), also transport nitrite into plasma through the same mechanism. Because of the relationship between nitrite uptake and the gill chloride uptake mechanism, nitrite uptake can provide insight regarding the method of chloride uptake for fish. This study was designed to determine if non-teleost fishes concentrate nitrite in their plasma, and to determine if chloride inhibits nitrite uptake in non-teleost fish. To determine if bowfin Amia calva, spotted gar Lepisosteus oculatus, alligator gar Atractosteus spatula, and paddlefish Polyodon spathula concentrate environmental nitrite in their plasma, individuals were exposed to concentrations of 0, 1, 10, or 100 mg/L nitrite-N. After exposure, all species had plasma nitrite-N concentrations greater than environmental levels. To determine if chloride inhibits nitrite uptake for spotted gar, alligator gar, and paddlefish, fish were exposed to 1 mg/L nitrite-N and 20 mg/L chloride as calcium chloride, or to 1 mg/L nitrite-N only. Chloride effectively prevented nitrite from being concentrated in the plasma of all species. It appears that non-teleost fish concentrate nitrite in their plasma via their chloride uptake mechanism and that this is an ancestral characteristic for teleost.

Bimodal effect of hydrogen peroxide and oxidative events in nitrite-induced rapid root abscission by the water fern Azolla pinnata

DOE PAGES

Cohen, Michael F.; Gurung, Sushma; Birarda, Giovanni; ...

2015-07-09

In the genus Azolla rapid abscission of roots from floating fronds occurs within minutes in response to a variety of stresses, including exposure to nitrite. We found that hydrogen peroxide, though itself not an inducer of root abscission, modulates nitrite-induced root abscission by Azolla pinnata in a dose-dependent manner, with 2 mM H 2O 2 significantly diminishing the responsiveness to 2 mM NaNO 2, and 10 mM H 2O 2 slightly enhancing it. Hypoxia, which has been found in other plants to result in autogenic production of H 2O 2, dramatically stimulated root abscission of A. pinnata in response tomore » nitrite, especially for plants previously cultivated in medium containing 5 mM KNO 3 compared to plants cultivated under N 2-fixing conditions without combined nitrogen. Plants, including Azolla, produce the small signaling molecule nitric oxide (NO) from nitrite using nitrate reductase. We found Azolla plants to display dose-dependent root abscission in response to the NO donor spermine NONOate. Treatment of plants with the thiol-modifying agents S-methyl methanethiosulfonate or glutathione inhibited the nitrite-induced root abscission response. Synchrotron radiation-based Fourier transform infrared spectromicroscopy revealed higher levels of carbonylation in the abscission zone of dropped roots, indicative of reaction products of polysaccharides with potent free radical oxidants. Lastly, we hypothesize that metabolic products of nitrite and NO react with H 2O 2 in the apoplast leading to free-radical-mediated cleavage of structural polysaccharides and consequent rapid root abscission.« less

Bimodal effect of hydrogen peroxide and oxidative events in nitrite-induced rapid root abscission by the water fern Azolla pinnata.

PubMed

Cohen, Michael F; Gurung, Sushma; Birarda, Giovanni; Holman, Hoi-Ying N; Yamasaki, Hideo

2015-01-01

In the genus Azolla rapid abscission of roots from floating fronds occurs within minutes in response to a variety of stresses, including exposure to nitrite. We found that hydrogen peroxide, though itself not an inducer of root abscission, modulates nitrite-induced root abscission by Azolla pinnata in a dose-dependent manner, with 2 mM H2O2 significantly diminishing the responsiveness to 2 mM NaNO2, and 10 mM H2O2 slightly enhancing it. Hypoxia, which has been found in other plants to result in autogenic production of H2O2, dramatically stimulated root abscission of A. pinnata in response to nitrite, especially for plants previously cultivated in medium containing 5 mM KNO3 compared to plants cultivated under N2-fixing conditions without combined nitrogen. Plants, including Azolla, produce the small signaling molecule nitric oxide (NO) from nitrite using nitrate reductase. We found Azolla plants to display dose-dependent root abscission in response to the NO donor spermine NONOate. Treatment of plants with the thiol-modifying agents S-methyl methanethiosulfonate or glutathione inhibited the nitrite-induced root abscission response. Synchrotron radiation-based Fourier transform infrared spectromicroscopy revealed higher levels of carbonylation in the abscission zone of dropped roots, indicative of reaction products of polysaccharides with potent free radical oxidants. We hypothesize that metabolic products of nitrite and NO react with H2O2 in the apoplast leading to free-radical-mediated cleavage of structural polysaccharides and consequent rapid root abscission.

Bimodal effect of hydrogen peroxide and oxidative events in nitrite-induced rapid root abscission by the water fern Azolla pinnata

PubMed Central

Cohen, Michael F.; Gurung, Sushma; Birarda, Giovanni; Holman, Hoi-Ying N.; Yamasaki, Hideo

2015-01-01

In the genus Azolla rapid abscission of roots from floating fronds occurs within minutes in response to a variety of stresses, including exposure to nitrite. We found that hydrogen peroxide, though itself not an inducer of root abscission, modulates nitrite-induced root abscission by Azolla pinnata in a dose-dependent manner, with 2 mM H2O2 significantly diminishing the responsiveness to 2 mM NaNO2, and 10 mM H2O2 slightly enhancing it. Hypoxia, which has been found in other plants to result in autogenic production of H2O2, dramatically stimulated root abscission of A. pinnata in response to nitrite, especially for plants previously cultivated in medium containing 5 mM KNO3 compared to plants cultivated under N2-fixing conditions without combined nitrogen. Plants, including Azolla, produce the small signaling molecule nitric oxide (NO) from nitrite using nitrate reductase. We found Azolla plants to display dose-dependent root abscission in response to the NO donor spermine NONOate. Treatment of plants with the thiol-modifying agents S-methyl methanethiosulfonate or glutathione inhibited the nitrite-induced root abscission response. Synchrotron radiation-based Fourier transform infrared spectromicroscopy revealed higher levels of carbonylation in the abscission zone of dropped roots, indicative of reaction products of polysaccharides with potent free radical oxidants. We hypothesize that metabolic products of nitrite and NO react with H2O2 in the apoplast leading to free-radical-mediated cleavage of structural polysaccharides and consequent rapid root abscission. PMID:26217368

Chemical quality of bottom sediments in selected streams, Jefferson County, Kentucky, April-July 1992

USGS Publications Warehouse

Moore, B.L.; Evaldi, R.D.

1995-01-01

Bottom sediments from 25 stream sites in Jefferson County, Ky., were analyzed for percent volatile solids and concentrations of nutrients, major metals, trace elements, miscellaneous inorganic compounds, and selected organic compounds. Statistical high outliers of the constituent concentrations analyzed for in the bottom sediments were defined as a measure of possible elevated concentrations. Statistical high outliers were determined for at least 1 constituent at each of 12 sampling sites in Jefferson County. Of the 10 stream basins sampled in Jefferson County, the Middle Fork Beargrass Basin, Cedar Creek Basin, and Harrods Creek Basin were the only three basins where a statistical high outlier was not found for any of the measured constituents. In the Pennsylvania Run Basin, total volatile solids, nitrate plus nitrite, and endrin constituents were statistical high outliers. Pond Creek was the only basin where five constituents were statistical high outliers-barium, beryllium, cadmium, chromium, and silver. Nitrate plus nitrite and copper constituents were the only statistical high outliers found in the Mill Creek Basin. In the Floyds Fork Basin, nitrate plus nitrite, phosphorus, mercury, and silver constituents were the only statistical high outliers. Ammonia was the only statistical high outlier found in the South Fork Beargrass Basin. In the Goose Creek Basin, mercury and silver constituents were the only statistical high outliers. Cyanide was the only statistical high outlier in the Muddy Fork Basin.

Time-dependent depletion of nitrite in pork/beef and chicken meat products and its effect on nitrite intake estimation.

PubMed

Merino, Leonardo; Darnerud, Per Ola; Toldrá, Fidel; Ilbäck, Nils-Gunnar

2016-01-01

The food additive nitrite (E249, E250) is commonly used in meat curing as a food preservation method. Because of potential negative health effects of nitrite, its use is strictly regulated. In an earlier study we have shown that the calculated intake of nitrite in children can exceed the acceptable daily intake (ADI) when conversion from dietary nitrate to nitrite is included. This study examined time-dependent changes in nitrite levels in four Swedish meat products frequently eaten by children: pork/beef sausage, liver paté and two types of chicken sausage, and how the production process, storage and also boiling (e.g., simmering in salted water) and frying affect the initial added nitrite level. The results showed a steep decrease in nitrite level between the point of addition to the product and the first sampling of the product 24 h later. After this time, residual nitrite levels continued to decrease, but much more slowly, until the recommended use-by date. Interestingly, this continuing decrease in nitrite was much smaller in the chicken products than in the pork/beef products. In a pilot study on pork/beef sausage, we found no effects of boiling on residual nitrite levels, but frying decreased nitrite levels by 50%. In scenarios of time-dependent depletion of nitrite using the data obtained for sausages to represent all cured meat products and including conversion from dietary nitrate, calculated nitrite intake in 4-year-old children generally exceeded the ADI. Moreover, the actual intake of nitrite from cured meat is dependent on the type of meat source, with a higher residual nitrite levels in chicken products compared with pork/beef products. This may result in increased nitrite exposure among consumers shifting their consumption pattern of processed meats from red to white meat products.

Time-dependent depletion of nitrite in pork/beef and chicken meat products and its effect on nitrite intake estimation

PubMed Central

Merino, Leonardo; Darnerud, Per Ola; Toldrá, Fidel; Ilbäck, Nils-Gunnar

2016-01-01

ABSTRACT The food additive nitrite (E249, E250) is commonly used in meat curing as a food preservation method. Because of potential negative health effects of nitrite, its use is strictly regulated. In an earlier study we have shown that the calculated intake of nitrite in children can exceed the acceptable daily intake (ADI) when conversion from dietary nitrate to nitrite is included. This study examined time-dependent changes in nitrite levels in four Swedish meat products frequently eaten by children: pork/beef sausage, liver paté and two types of chicken sausage, and how the production process, storage and also boiling (e.g., simmering in salted water) and frying affect the initial added nitrite level. The results showed a steep decrease in nitrite level between the point of addition to the product and the first sampling of the product 24 h later. After this time, residual nitrite levels continued to decrease, but much more slowly, until the recommended use-by date. Interestingly, this continuing decrease in nitrite was much smaller in the chicken products than in the pork/beef products. In a pilot study on pork/beef sausage, we found no effects of boiling on residual nitrite levels, but frying decreased nitrite levels by 50%. In scenarios of time-dependent depletion of nitrite using the data obtained for sausages to represent all cured meat products and including conversion from dietary nitrate, calculated nitrite intake in 4-year-old children generally exceeded the ADI. Moreover, the actual intake of nitrite from cured meat is dependent on the type of meat source, with a higher residual nitrite levels in chicken products compared with pork/beef products. This may result in increased nitrite exposure among consumers shifting their consumption pattern of processed meats from red to white meat products. PMID:26743589

Enterosalivary nitrate metabolism and the microbiome: Intersection of microbial metabolism, nitric oxide and diet in cardiac and pulmonary vascular health.

PubMed

Koch, Carl D; Gladwin, Mark T; Freeman, Bruce A; Lundberg, Jon O; Weitzberg, Eddie; Morris, Alison

2017-04-01

Recent insights into the bioactivation and signaling actions of inorganic, dietary nitrate and nitrite now suggest a critical role for the microbiome in the development of cardiac and pulmonary vascular diseases. Once thought to be the inert, end-products of endothelial-derived nitric oxide (NO) heme-oxidation, nitrate and nitrite are now considered major sources of exogenous NO that exhibit enhanced vasoactive signaling activity under conditions of hypoxia and stress. The bioavailability of nitrate and nitrite depend on the enzymatic reduction of nitrate to nitrite by a unique set of bacterial nitrate reductase enzymes possessed by specific bacterial populations in the mammalian mouth and gut. The pathogenesis of pulmonary hypertension (PH), obesity, hypertension and CVD are linked to defects in NO signaling, suggesting a role for commensal oral bacteria to shape the development of PH through the formation of nitrite, NO and other bioactive nitrogen oxides. Oral supplementation with inorganic nitrate or nitrate-containing foods exert pleiotropic, beneficial vascular effects in the setting of inflammation, endothelial dysfunction, ischemia-reperfusion injury and in pre-clinical models of PH, while traditional high-nitrate dietary patterns are associated with beneficial outcomes in hypertension, obesity and CVD. These observations highlight the potential of the microbiome in the development of novel nitrate- and nitrite-based therapeutics for PH, CVD and their risk factors. Copyright © 2017 Elsevier Inc. All rights reserved.

Simultaneous pyridine biodegradation and nitrogen removal in an aerobic granular system.

PubMed

Liu, Xiaodong; Wu, Shijing; Zhang, Dejin; Shen, Jinyou; Han, Weiqing; Sun, Xiuyun; Li, Jiansheng; Wang, Lianjun

2018-05-01

Simultaneous pyridine biodegradation and nitrogen removal were successfully achieved in a sequencing batch reactor (SBR) based on aerobic granules. In a typical SBR cycle, nitritation occurred obviously after the majority of pyridine was removed, while denitrification occurred at early stage of the cycle when oxygen consumption was aggravated. The effect of several key operation parameters, i.e., air flow rate, influent NH 4 + -N concentration, influent pH and pyridine concentration, on nitritation, pyridine degradation and total nitrogen (TN) removal, was systematically investigated. The results indicated that high air flow rate had a positive effect on both pyridine degradation and nitritation but a negative impact of overhigh air flow rate. With the increase of NH 4 + dosage, both nitritation and TN removal could be severely inhibited. Slightly alkaline condition, i.e., pH7.0-8.0, was beneficial for both pyridine degradation and nitritation. High pyridine dosage often resulted in the delay of both pyridine degradation and nitritation. Besides, extracellular polymeric substances production was affected by air flow rate, NH 4 + dosage, pyridine dosage and pH. In addition, high-throughput sequencing analysis demonstrated that Bdellovibrio and Paracoccus were the dominant species in the aerobic granulation system. Coexistence of pyridine degrader, nitrification related species, denitrification related species, polymeric substances producer and self-aggregation related species was also confirmed by high-throughput sequencing. Copyright © 2017. Published by Elsevier B.V.

Microbiological Safety of Processed Meat Products Formulated with Low Nitrite Concentration: A Mini Review.

PubMed

Lee, Soomin; Lee, Heeyoung; Kim, Sejeong; Lee, Jeeyeon; Ha, Jimyeong; Choi, Yukyung; Oh, Hyemin; Choi, Kyoung-Hee; Yoon, Yohan

2018-03-13

Nitrite plays a major role in inhibiting the growth of foodborne pathogens, including Clostridium botulinum that causes botulism, a life-threatening disease. Nitrite serves as a color-fixing agent in processed meat products. However, N-nitroso compounds can be produced from nitrite. They are considered as carcinogens. Thus, consumers desire processed meat products that contain lower concentrations (below conventional concentrations of products) of nitrite or no nitrite at all, although the portion of nitrite intake by processed meat consumption in total nitrite intake is very low. However, lower nitrite levels might expose consumers to risk of botulism poisoning due to C. botulinum or illness caused by other foodborne pathogens. Hence, lower nitrite concentrations in combination with other factors such as low pH, high NaCl level, and others have been recommended to decrease the risk of food poisoning. In addition, natural compounds that can inhibit bacterial growth and function as color-fixing agents have been developed to replace nitrite in processed meat products. However, their antibotulinal effects have not been fully clarified. Therefore, to have processed meat products with lower nitrite concentrations, low pH, high NaCl concentration, and others should also be applied together. Before using natural compounds as replacement of nitrite, their antibotulinal activities should be examined.

Nitrogen removal and electricity production at a double-chamber microbial fuel cell with cathode nitrite denitrification.

PubMed

Yu, Yangyang; Zhao, Jianqiang; Wang, Sha; Zhao, Huimin; Ding, Xiaoqian; Gao, Kun

2017-12-01

Double-chamber microbial fuel cell was applied to investigate the performance of the electricity production and nitrite denitrification through feeding nitrite into the cathode. Factors influencing denitrification performance and power production, such as external resistance, influent nitrite concentration and Nitrite Oxygen Bacteria inhibitors, were studied. The results show that when the concentration of nitrite nitrogen and external resistance were 100 mg L -1 and 10 Ω, respectively, the nitrite denitrification reached the best state. The NaN 3 can inhibit nitrite oxidation effectively; meanwhile, the nitrite denitrification with N 2 O as the final products was largely improved. The [Formula: see text] was reduced to [Formula: see text], causing the cathode denitrification coulombic efficiency to exceed 100%. In chemoautotrophic bio-nitrification, microorganisms may utilize H 2 O to oxidize nitrite under anaerobic conditions. Proteobacteria might play a major role in the process of denitrification in MFC.

Regulation of nitrite resistance of the cytochrome cbb3 oxidase by cytochrome c ScyA in Shewanella oneidensis

PubMed Central

Yin, Jianhua; Jin, Miao; Zhang, Haiyan; Ju, Lili; Zhang, Lili; Gao, Haichun

2015-01-01

Cytochrome c proteins, as enzymes to exchange electrons with substrates or as pure electron carriers to shuttle electrons, play vital roles in bacterial respiration and photosynthesis. In Shewanella oneidensis, a research model for the respiratory diversity, at least 42 c-type cytochromes are predicted to be encoded in the genome and are regarded to be the foundation of its highly branched electron transport pathways. However, only a small number of c-type cytochromes have been extensively studied. In this study, we identify soluble cytochrome c ScyA as an important factor influencing the nitrite resistance of a strain devoid of the bd oxidase by utilizing a newly developed transposon mutagenesis vector, which enables overexpression of the gene(s) downstream of the insertion site. We show that when in overabundance ScyA facilitates growth against nitrite inhibition by enhancing nitrite resistance of the cbb3 oxidase. Based on the data presented in this study, we suggest two possible mechanisms underlying the observed effect of ScyA: (1) ScyA increases electron flow to the cbb3 oxidase; (2) ScyA promotes nitrite resistance of the cbb3 oxidase, possibly by direct interaction. PMID:25417822

[Study of scavenging activity of sorghum pigment to hydroxyl free radicals by fluorimetry].

PubMed

Zhang, Hai-rong; Wang, Wen-yan

2007-03-01

A natural product, sorghum pigment, consists of a number of important flavonoid derivatives, occurrs on the seed capsules or in the stems of many sorghums, and is widely applied in different fields of food, cosmetic and dyeing industries, It is important for scavenging hydroxyl free radicals and protection of human healthiness. Scavenging capacities of hydroxyl free radicals with sodium nitrite, quercetin and sorghum pigment were comparatively researched by fluorimetry, and the model of hydroxyl free radicals produced is based on the reaction of Cu2+ -catalyzed oxidation of ascorbic acid in the presence of hydrogen peroxide. The hydroxyl radicals react with benzoic acid, forming a fluorescent product, and the fluorescence intensity was determined by the concentration of hydroxybenzoic acid. The experimental results show that the sodium nitrite, quercetin and sorghum pigment have a quantity-effect relationship for scavenging hydroxyl free radicals, and sodium nitrite and quercetin in comparison with sorghum pigment have high antioxidant capacity. Finally, the quenching mechanisms were explored with sodium nitrite, sorghum pigment, and quercetin respectively. The sorghum pigment and sodium nitrite feature a dynamic quenching processes, while quercetin shows a static quenching processes. A reference method was provided for reasonable exploitation and utilization of sorghum pigment.

A coastal surface seawater analyzer for nitrogenous nutrient mapping

NASA Astrophysics Data System (ADS)

Masserini, Robert T.; Fanning, Kent A.; Hendrix, Steven A.; Kleiman, Brittany M.

2017-11-01

Satellite-data-based modeling of chlorophyll indicates that ocean waters in the mesosphere category are responsible for the majority of oceanic net primary productivity. Coastal waters, which frequently have surface chlorophyll values in the mesosphere range and have strong horizontal chlorophyll gradients and large temporal variations. Thus programs of detailed coastal nutrient surveys are essential to the study of the dynamics of oceanic net primary productivity, along with land use impacts on estuarine and coastal ecosystems. The degree of variability in these regions necessitates flexible instrumentation capable of near real-time analysis to detect and monitor analytes of interest. This work describes the development of a portable coastal surface seawater analyzer for nutrient mapping that can simultaneously elucidate with high resolution the distribution of nitrate, nitrite, and ammonium - the three principal nitrogenous inorganic nutrients in coastal systems. The approach focuses on the use of pulsed xenon flash lamps to construct an analyzer which can be adapted to any automated chemistry with fluorescence detection. The system has two heaters, on-the-fly standardization, on-board data logging, an independent 24 volt direct current power supply, internal local operating network, a 12 channel peristaltic pump, four rotary injection/selection valves, and an intuitive graphical user interface. Using the methodology of Masserini and Fanning (2000) the detection limits for ammonium, nitrite, and nitrate plus nitrite were 11, 10, and 22 nM, respectively. A field test of the analyzer in Gulf of Mexico coastal waters demonstrated its ability to monitor and delineate the complexity of inorganic nitrogen nutrient enrichments within a coastal system.

Hemodynamic effects of IV sodium nitrite in hospitalized comatose survivors of out of hospital cardiac arrest.

PubMed

Dezfulian, Cameron; Olsufka, Michele; Fly, Deborah; Scruggs, Sue; Do, Rose; Maynard, Charles; Nichol, Graham; Kim, Francis

2018-01-01

Patients resuscitated from cardiac arrest have brain and cardiac injury. Recent animal studies suggest that the administration of sodium nitrite after resuscitation from 12min of asystole limits acute cardiac dysfunction and improves survival and neurologic outcomes. It has been hypothesized that low doses of IV sodium nitrite given during resuscitation of out of hospital cardiac arrest (OHCA) will improve survival. Low doses of sodium nitrite (e.g., 9.6mg of sodium nitrite) are safe in healthy individuals, however the effect of nitrite on blood pressure in resuscitated cardiac arrest patients is unknown. We performed a single-center, pilot trial of low dose sodium nitrite (1 or 9.6mg dose) vs. placebo in hospitalized out-of-hospital cardiac arrest patient to determine whether nitrite administration reduced blood pressure and whether whole blood nitrite levels increased in response to nitrite administration. This is the first reported study of sodium nitrite in cardiac arrest patients. Infusion of low doses of sodium nitrite in comatose survivors of OHCA (n=7) compared to placebo (n=4) had no significant effects on heart rate within 30min after infusion (70±20 vs. 78±3 beats per minute, p=0.18), systolic blood pressure (103±20 vs 108±15mmHg, p=0.3), or methemoglobin levels (0.92±0.33 vs. 0.70±0.26, p=0.45). Serum nitrite levels of 2-4μM were achieved within 15min of a 9.6mg nitrite infusion. Low dose sodium nitrite does not cause significant hemodynamic effect in patients with OHCA, which suggests that nitrite can be delivered safely in this critically ill patient population. Higher doses of sodium nitrite are necessary in order to achieve target serum level of 10μM. Copyright © 2017 Elsevier B.V. All rights reserved.

Metabolism of nitrate in fermented meats: the characteristic feature of a specific group of fermented foods.

PubMed

Hammes, Walter P

2012-04-01

Within the universe of food fermentation processes the multi-purpose use of nitrate and/or nitrite is a unique characteristic of meat fermentations. These curing agents play a decisive role in obtaining the specific sensory properties, stability and hygienic safety of products such as fermented sausages, ham and, more recently, emulsion type of sausages. The use of nitrate is the traditional method in curing processes and requires its reduction to reactive nitrite. Thus, nitrate reduction is the key event that is exclusively performed by microorganisms. Under controlled fermentation conditions starter cultures are used that contain staphylococci and/or Kocuria varians, which in addition to strongly affecting sensory properties exhibit efficient nitrate reductase activity. To obtain clean label products some plant sources of nitrate have been in use. When producing thermally treated sausages (e.g. of emulsion type), starter cultures are used that form nitrite before cooking takes place. Staphylococci reduce nitrite to ammonia after nitrate has been consumed. K. varians is devoid of nitrite reductase activity. Nitrate and nitrite reductases are also present in certain strains of lactobacilli. It was shown that their application as starter cultures warrants efficient activity in sausages made with either nitrate or nitrite. NO is formed from nitrite in numerous chemical reactions among which disproportionation and reaction with reductants either added or endogenous in meat are of practical importance. Numerous nitrosation and nitrosylation reactions take place in the meat matrix among which the formation of nitrosomyoglobin is of major sensory importance. Safety considerations in meat fermentation relate to the safe nature of the starter organisms and to the use of nitrate/nitrite. Staphylococci ("micrococci") in fermented meat have a long tradition in food use but have not received the QPS status from the EFSA. They require, therefore, thorough assessment with regard to toxigenicity and pathogenicity determinants as well as presence of transferable antibiotic resistance. Nitrate and nitrite are still considered basically undesired in food. The main objections are based on their potential to form nitrosamines with carcinogenic potential. In view of new results from intensive research of NO, potential risks are opposed by positive effects on human health. Copyright © 2011 Elsevier Ltd. All rights reserved.

The Effects of Physicochemical Factors and Cell Density on Nitrite Transformation in a Lipid-Rich Chlorella.

PubMed

Liang, Fang; Du, Kui; Wen, Xiaobin; Luo, Liming; Geng, Yahong; Li, Yeguang

2015-12-28

To understand the effects of physicochemical factors on nitrite transformation by microalgae, a lipid-rich Chlorella with high nitrite tolerance was cultured with 8 mmol/l sodium nitrite as sole nitrogen source under different conditions. The results showed that nitrite transformation was mainly dependent on the metabolic activities of algal cells rather than oxidation of nitrite by dissolved oxygen. Light intensity, temperature, pH, NaHCO3 concentrations, and initial cell densities had significant effects on the rate of nitrite transformation. Single-factor experiments revealed that the optimum conditions for nitrite transformation were light intensity: 300 μmol/m(2); temperature: 30°C; pH: 7-8; NaHCO3 concentration: 2.0 g/l; and initial cell density: 0.15 g/l; and the highest nitrite transformation rate of 1.36 mmol/l/d was achieved. There was a positive correlation between nitrite transformation rate and the growth of Chlorella. The relationship between nitrite transformation rate (mg/l/d) and biomass productivity (g/l/d) could be described by the regression equation y = 61.3x (R(2) = 0.9665), meaning that 61.3 mg N element was assimilated by 1.0 g dry biomass on average, which indicated that the nitrite transformation is a process of consuming nitrite as nitrogen source by Chlorella. The results demonstrated that the Chlorella suspension was able to assimilate nitrite efficiently, which implied the feasibility of using flue gas for mass production of Chlorella without preliminary removal of NOX.

Oxidant-antioxidant status in Egyptian children with sickle cell anemia: a single center based study.

PubMed

El-Ghamrawy, Mona Kamal; Hanna, Wagdi Maurice; Abdel-Salam, Amina; El-Sonbaty, Marwa M; Youness, Eman R; Adel, Ahmed

2014-01-01

the present study was conducted to investigate the oxidant-antioxidant status in Egyptian children with sickle cell anemia. the serum levels of total antioxidant capacity (TAO), paraoxonase (PON), vitamin E, nitrite, and malondialdehyde (MDA) were measured in 40 steady state children with homozygous sickle cell anemia (24 males and 16 females) and 20 apparently healthy age- and gender-matched controls. mean serum TAO, PON, vitamin E, and nitrite levels were significantly lower in the group with sickle cell anemia, whereas mean serum MDA was significantly higher in these children compared to controls. No significant differences in mean levels of TAO, PON, nitrite, vitamin E, and MDA were found in sickle cell anemia patients receiving hydroxyurea when compared with those not receiving hydroxyurea. A significant negative correlation between serum nitrite and the occurrence of vaso-occlusive crises (VOC) was observed (r=-0.3, p=0.04). PON level was found to be positively correlated with patients' weight and BMI (r=-0.4, p=0.01; r=-0.7, p<0.001, respectively), but not with frequency of VOC. The area under the curve of serum nitrite in predicting occurrence of VOC was 0.782, versus 0.701 for PON, and 0.650 for TAO (p=0.006). Serum MDA was not correlated with nitrite, PON, TAO, or vitamin E levels. No significant correlations were detected between serum nitrite and hemoglobin or antioxidant enzymes. children with sickle cell anemia have chronic oxidative stress that may result in increased VOC, and decreased serum nitrite may be associated with increases in VOC frequency. A novel finding in this study is the decrease in PON level in these patients, which is an interesting subject for further research. Copyright © 2014 Sociedade Brasileira de Pediatria. Published by Elsevier Editora Ltda. All rights reserved.

Histological alterations in gills of Macrobrachium amazonicum juveniles exposed to ammonia and nitrite.

PubMed

Dutra, Fabrício Martins; Rönnau, Milton; Sponchiado, Dircelei; Forneck, Sandra Carla; Freire, Carolina Arruda; Ballester, Eduardo Luis Cupertino

2017-06-01

Aquaculture has shown great growth in the last decades. Due to the restrictions on water use, production systems are becoming increasingly more intensive, raising concerns about the production water quality. Macrobrachium amazonicum is among the freshwater prawn species with favorable characteristics for production and possibility of intensification. Nitrogen compounds such as ammonia and nitrite affect the health of aquatic organisms since they quickly reach toxic concentrations. These compounds can also cause damage to the gill structure, leading to hypoxia in tissues, affecting acid-base balance, osmoregulation (salt absorption) and ammonia excretion, decreasing the immune capacity of the animal and, in extreme cases, cause death. The aim of this study was to assess histological changes in the gills of Macrobrachium amazonicum juveniles subjected to different concentrations of total ammonia and nitrite. The prawns were subjected to different concentrations of those compounds and their gills were removed and preserved for histological analysis. The gills were assessed for changes according to the Organ Index (I org ) and, for each change, an importance factor (w) was attributed according to the degree of reversibility and applied according to the degree of extension or frequency of the damage. The damage to the gills in the treatments with 100% mortality, both for ammonia and nitrite, corresponded to the high occurrence of progressive, regressive, circulatory, and inflammation damages. The other treatments (which caused less mortality) had mainly inflammation and regressive damages, whose occurrence increased according to the increase in ammonia and nitrite concentration. The histological analysis confirmed that the higher the total ammonia and nitrite concentrations, the larger the damages caused to the gill structure and that lower nitrite concentrations caused similar damages to those caused by higher total ammonia concentrations, which reflects the lower capacity M. amazonicum has to tolerate nitrite. Copyright © 2017 Elsevier B.V. All rights reserved.

Characterization and inhibition of nitrite uptake in shortnose sturgeon fingerlings

USGS Publications Warehouse

Fontenot, Q.C.; Isely, J.J.; Tomasso, J.R.

1999-01-01

Efforts are underway to culture the endangered shortnose sturgeon Acipenser brevirostrum for possible reintroduction. As part of a larger project to develop culture techniques for this species, the uptake of nitrite was evaluated in fingerlings (16.5 ?? 4.85 g; mean ?? SD). Plasma nitrite concentrations increased significantly with exposure time (0-5 d) and dose (0-4 mg nitrite-N/L). Shortnose sturgeon fingerlings were able to concentrate nitrite in their plasma to more than 63 times the environmental concentration. Chloride, as either sodium chloride or calcium chloride, partially inhibited nitrite uptake. However, calcium chloride was a better inhibitor. After previous exposure (2 d at 2.13 ?? 0.080 mg nitrite-N/L) plasma nitrite-N decreased from 165.5 to 36.7 mg/L during a 3-d simultaneous exposure to 2.13 ?? 0.080 mg nitrite-N/L and treatment with 40 mg chloride/L as calcium chloride. The addition of calcium chloride to the water appeared to be an effective means of preventing nitrite uptake and treating nitrite toxicity in hatchery-reared shortnose sturgeon fingerlings.

Long-term straw returning affects Nitrospira-like nitrite oxidizing bacterial community in a rapeseed-rice rotation soil.

PubMed

Luo, Xuesong; Han, Shun; Lai, Songsong; Huang, Qiaoyun; Chen, Wenli

2017-04-01

Nitrospira are the most widespread and well known nitrite-oxidizing bacteria (NOB) and putatively key nitrite-oxidizers in acidic ecosystems. Nevertheless, their ecology in agriculture soils has not been well studied. To understand the impact of straw incorporation on soil Nitrospira-like bacterial community, a cloned library analysis of the nitrite oxidoreductase gene-nxrB was performed for a long-term rapeseed-rice rotation system. In this study, most members of the Nitrospira-like NOB in the paddy soils from the Wuxue field experiment station were phylogenetically related with Nitrospira lineages II. The Shannon diversity index possessed a decrease trend in the straw applied soils. The relative abundances of 16 OTUs (accounting 72% of the total OTUs, including 11 unique OTUs and 5 shared OTUs) were different between in the straw applied and control soils. These data suggested a selection effect from the long-term straw fertilization. Canonical correspondence analysis data showed that a centralized group of Nitrospira-like NOB OTUs in the community was partly explained by the soil ammonium, nitrate, available phosphorus, and the available potassium. This could suggest that straw fertilization led to the soil Nitrospira-like NOB community shift, which was correlated with the change of available nutrients in the bulk soil. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nitrate ammonification in mangrove soils: a hidden source of nitrite?

PubMed Central

Balk, Melike; Laverman, Anniet M.; Keuskamp, Joost A.; Laanbroek, Hendrikus J.

2015-01-01

Nitrate reduction is considered to be a minor microbial pathway in the oxidation of mangrove-derived organic matter due to a limited supply of nitrate in mangrove soils. At a limited availability of this electron acceptor compared to the supply of degradable carbon, nitrate ammonification is thought to be the preferential pathway of nitrate reduction. Mangrove forest mutually differ in their productivity, which may lead to different available carbon to nitrate ratios in their soil. Hence, nitrate ammonification is expected to be of more importance in high- compared to low-productive forests. The hypothesis was tested in flow-through reactors that contain undisturbed mangrove soils from high-productive Avicennia germinans and Rhizophora mangle forests in Florida and low-productive Avicennia marina forests in Saudi Arabia. Nitrate was undetectable in the soils from both regions. It was assumed that a legacy of nitrate ammonification would be reflected by a higher ammonium production from these soils upon the addition of nitrate. Unexpectedly, the soils from the low-productive forests in Saudi Arabia produced considerably more ammonium than the soils from the high-productive forests in Florida. Hence, other environmental factors than productivity must govern the selection of nitrate ammonification or denitrification. A rather intriguing observation was the 1:1 production of nitrite and ammonium during the consumption of nitrate, more or less independent from sampling region, location, sampling depth, mangrove species and from the absence or presence of additional degradable carbon. This 1:1 ratio points to a coupled production of ammonium and nitrite by one group of nitrate-reducing microorganisms. Such a production of nitrite will be hidden by the presence of active nitrite-reducing microorganisms under the nitrate-limited conditions of most mangrove forest soils. PMID:25784903

Nitrate ammonification in mangrove soils: a hidden source of nitrite?

PubMed

Balk, Melike; Laverman, Anniet M; Keuskamp, Joost A; Laanbroek, Hendrikus J

2015-01-01

Nitrate reduction is considered to be a minor microbial pathway in the oxidation of mangrove-derived organic matter due to a limited supply of nitrate in mangrove soils. At a limited availability of this electron acceptor compared to the supply of degradable carbon, nitrate ammonification is thought to be the preferential pathway of nitrate reduction. Mangrove forest mutually differ in their productivity, which may lead to different available carbon to nitrate ratios in their soil. Hence, nitrate ammonification is expected to be of more importance in high- compared to low-productive forests. The hypothesis was tested in flow-through reactors that contain undisturbed mangrove soils from high-productive Avicennia germinans and Rhizophora mangle forests in Florida and low-productive Avicennia marina forests in Saudi Arabia. Nitrate was undetectable in the soils from both regions. It was assumed that a legacy of nitrate ammonification would be reflected by a higher ammonium production from these soils upon the addition of nitrate. Unexpectedly, the soils from the low-productive forests in Saudi Arabia produced considerably more ammonium than the soils from the high-productive forests in Florida. Hence, other environmental factors than productivity must govern the selection of nitrate ammonification or denitrification. A rather intriguing observation was the 1:1 production of nitrite and ammonium during the consumption of nitrate, more or less independent from sampling region, location, sampling depth, mangrove species and from the absence or presence of additional degradable carbon. This 1:1 ratio points to a coupled production of ammonium and nitrite by one group of nitrate-reducing microorganisms. Such a production of nitrite will be hidden by the presence of active nitrite-reducing microorganisms under the nitrate-limited conditions of most mangrove forest soils.

Impact of chorioamnionitis on exhaled nitric oxide and endotracheal aspirate levels of nitrites-nitrates and interleukin-8 in mechanically ventilated preterm neonates.

PubMed

Figueras-Aloy, Josep; Salvia-Roiges, Maria Dolors; Rodriguez-Miguélez, J Manuel; Miracle-Echegoyen, Xavier; Botet-Mussons, Francesc; Marín-Soria, J Luís; Carbonell-Estrany, Xavier

2011-06-01

To assess the influence of maternal chorioamnionitis on early exhaled nitric oxide (NO) and levels of nitrites-nitrates and interleukin (IL)-8 in endotracheal aspirate fluid in mechanically ventilated preterm neonates. Cross-sectional study. PATIENT-SUBJECT SELECTION: Between September 2007 and August 2009, 54 mechanically ventilated preterm neonates were included. Patients were divided into two groups according to the presence or absence of maternal chorioamnionitis, and those without chorioamnionitis (controls) were further stratified into two subgroups by birth weight < or ≥ 2,000 g. The ventilator used was a Babylog 8000. The NO level assessed was the plateau value given by the software of the Sievers NOA apparatus. Collection of endotracheal aspirate fluid samples was performed coinciding with routine aspirations and using the dry technique. The two groups of control neonates showed statistically significant differences in exhaled NO expressed as nl/min and normalized exhaled NO expressed as either nl/min or nl/min/kg, so they are not homogeneous and cannot be used in clinical practice. Serum C-reactive protein and endotracheal aspirate levels of nitrites-nitrates were significantly higher in the chorioamnionitis group than in controls (3.6 vs. 1.07 µmol/L; P = 0.035). Nitrites-nitrates levels were positively correlated with exhaled NO in ppb (ρ = 0.367; P = 0.006). Minute exhaled endogenous NO was significantly higher in the chorioamnionitis group (0.48 vs. 0.27 nl/min/kg; P = 0.021). In mechanically ventilated preterm infants weighing <2,000 g, maternal chorioamnionitis was associated with an increase of early exhaled NO (nl/min/kg) and serum levels of C-reactive protein and levels of nitrites-nitrates in endotracheal aspirate fluid. Copyright © 2011 Wiley-Liss, Inc.

Comparison of different two-pathway models for describing the combined effect of DO and nitrite on the nitrous oxide production by ammonia-oxidizing bacteria.

PubMed

Lang, Longqi; Pocquet, Mathieu; Ni, Bing-Jie; Yuan, Zhiguo; Spérandio, Mathieu

2017-02-01

The aim of this work is to compare the capability of two recently proposed two-pathway models for predicting nitrous oxide (N 2 O) production by ammonia-oxidizing bacteria (AOB) for varying ranges of dissolved oxygen (DO) and nitrite. The first model includes the electron carriers whereas the second model is based on direct coupling of electron donors and acceptors. Simulations are confronted to extensive sets of experiments (43 batches) from different studies with three different microbial systems. Despite their different mathematical structures, both models could well and similarly describe the combined effect of DO and nitrite on N 2 O production rate and emission factor. The model-predicted contributions for nitrifier denitrification pathway and hydroxylamine pathway also matched well with the available isotopic measurements. Based on sensitivity analysis, calibration procedures are described and discussed for facilitating the future use of those models.

Nitrite oxidation in the Namibian oxygen minimum zone.

PubMed

Füssel, Jessika; Lam, Phyllis; Lavik, Gaute; Jensen, Marlene M; Holtappels, Moritz; Günter, Marcel; Kuypers, Marcel M M

2012-06-01

Nitrite oxidation is the second step of nitrification. It is the primary source of oceanic nitrate, the predominant form of bioavailable nitrogen in the ocean. Despite its obvious importance, nitrite oxidation has rarely been investigated in marine settings. We determined nitrite oxidation rates directly in (15)N-incubation experiments and compared the rates with those of nitrate reduction to nitrite, ammonia oxidation, anammox, denitrification, as well as dissimilatory nitrate/nitrite reduction to ammonium in the Namibian oxygen minimum zone (OMZ). Nitrite oxidation (≤372 nM NO(2)(-) d(-1)) was detected throughout the OMZ even when in situ oxygen concentrations were low to non-detectable. Nitrite oxidation rates often exceeded ammonia oxidation rates, whereas nitrate reduction served as an alternative and significant source of nitrite. Nitrite oxidation and anammox co-occurred in these oxygen-deficient waters, suggesting that nitrite-oxidizing bacteria (NOB) likely compete with anammox bacteria for nitrite when substrate availability became low. Among all of the known NOB genera targeted via catalyzed reporter deposition fluorescence in situ hybridization, only Nitrospina and Nitrococcus were detectable in the Namibian OMZ samples investigated. These NOB were abundant throughout the OMZ and contributed up to ~9% of total microbial community. Our combined results reveal that a considerable fraction of the recently recycled nitrogen or reduced NO(3)(-) was re-oxidized back to NO(3)(-) via nitrite oxidation, instead of being lost from the system through the anammox or denitrification pathways.

Comparative analysis of nitrite uptake and hemoglobin-nitrite reactions in erythrocytes: sorting out uptake mechanisms and oxygenation dependencies.

PubMed

Jensen, Frank B; Rohde, Sabina

2010-04-01

Nitrite uptake into red blood cells (RBCs) precedes its intracellular reactions with hemoglobin (Hb) that forms nitric oxide (NO) during hypoxia. We investigated the uptake of nitrite and its reactions with Hb at different oxygen saturations (So(2)), using RBCs with (carp and rabbit) and without (hagfish and lamprey) anion exchanger-1 (AE1) in the membrane, with the aim to unravel the mechanisms and oxygenation dependencies of nitrite transport. Added nitrite rapidly diffused into the RBCs until equilibrium. The distribution ratio of nitrite across the membrane agreed with that expected from HNO(2) diffusion and AE1-mediated facilitated NO(2)(-) diffusion. Participation of HNO(2) diffusion was emphasized by rapid transmembrane nitrite equilibration also in the natural AE1 knockouts. Following the equilibration, nitrite was consumed by reacting with Hb, which created a continued inward diffusion controlled by intracellular reaction rates. Changes in nitrite uptake with So(2), pH, or species were accordingly explained by corresponding changes in reaction rates. In carp, nitrite uptake rates increased linearly with decreasing So(2) over the entire So(2) range. In rabbit, nitrite uptake rates were highest at intermediate So(2), producing a bell-shaped relationship with So(2). Nitrite consumption increased approximately 10-fold with a 1 unit decrease in pH, as expected from the involvement of protons in the reactions with Hb. The reaction of nitrite with deoxyhemoglobin was favored over that with oxyhemoglobin at intermediate So(2). We propose a model for RBC nitrite uptake that involves both HNO(2) diffusion and AE1-mediated transport and that explains both the present and previous (sometimes puzzling) results.

Aggregate Size and Architecture Determine Microbial Activity Balance for One-Stage Partial Nitritation and Anammox ▿

PubMed Central

Vlaeminck, Siegfried E.; Terada, Akihiko; Smets, Barth F.; De Clippeleir, Haydée; Schaubroeck, Thomas; Bolca, Selin; Demeestere, Lien; Mast, Jan; Boon, Nico; Carballa, Marta; Verstraete, Willy

2010-01-01

Aerobic ammonium-oxidizing bacteria (AerAOB) and anoxic ammonium-oxidizing bacteria (AnAOB) cooperate in partial nitritation/anammox systems to remove ammonium from wastewater. In this process, large granular microbial aggregates enhance the performance, but little is known about granulation so far. In this study, three suspended-growth oxygen-limited autotrophic nitrification-denitrification (OLAND) reactors with different inoculation and operation (mixing and aeration) conditions, designated reactors A, B, and C, were used. The test objectives were (i) to quantify the AerAOB and AnAOB abundance and the activity balance for the different aggregate sizes and (ii) to relate aggregate morphology, size distribution, and architecture putatively to the inoculation and operation of the three reactors. A nitrite accumulation rate ratio (NARR) was defined as the net aerobic nitrite production rate divided by the anoxic nitrite consumption rate. The smallest reactor A, B, and C aggregates were nitrite sources (NARR, >1.7). Large reactor A and C aggregates were granules capable of autonomous nitrogen removal (NARR, 0.6 to 1.1) with internal AnAOB zones surrounded by an AerAOB rim. Around 50% of the autotrophic space in these granules consisted of AerAOB- and AnAOB-specific extracellular polymeric substances. Large reactor B aggregates were thin film-like nitrite sinks (NARR, <0.5) in which AnAOB were not shielded by an AerAOB layer. Voids and channels occupied 13 to 17% of the anoxic zone of AnAOB-rich aggregates (reactors B and C). The hypothesized granulation pathways include granule replication by division and budding and are driven by growth and/or decay based on species-specific physiology and by hydrodynamic shear and mixing. PMID:19948857

Meat and components of meat and the risk of bladder cancer in the NIH-AARP Diet and Health Study.

PubMed

Ferrucci, Leah M; Sinha, Rashmi; Ward, Mary H; Graubard, Barry I; Hollenbeck, Albert R; Kilfoy, Briseis A; Schatzkin, Arthur; Michaud, Dominique S; Cross, Amanda J

2010-09-15

Meat could be involved in bladder carcinogenesis via multiple potentially carcinogenic meat-related compounds related to cooking and processing, including nitrate, nitrite, heterocyclic amines (HCAs), and polycyclic aromatic hydrocarbons (PAHs). The authors comprehensively investigated the association between meat and meat components and bladder cancer. During 7 years of follow-up, 854 transitional cell bladder-cancer cases were identified among 300,933 men and women who had completed a validated food-frequency questionnaire in the large prospective NIH-AARP Diet and Health Study. The authors estimated intake of nitrate and nitrite from processed meat and HCAs and PAHs from cooked meat by using quantitative databases of measured values. Total dietary nitrate and nitrite were calculated based on literature values. The hazard ratios (HR) and 95% confidence intervals (CI) for red meat (HR for fifth quintile compared with first quintile, 1.22; 95% CI, 0.96-1.54; P(trend) = .07) and the HCA 2-amino-1 methyl-6-phenylimidazo(4,5-b)pyridine (PhIP) (HR, 1.19; 95% CI, 0.95-1.48; P(trend) = .06) conferred a borderline statistically significant increased risk of bladder cancer. Positive associations were observed in the top quintile for total dietary nitrite (HR, 1.28; 95% CI, 1.02-1.61; P(trend) = .06) and nitrate plus nitrite intake from processed meat (HR, 1.29; 95% CI, 1.00-1.67; P(trend) = .11). These findings provided modest support for an increased risk of bladder cancer with total dietary nitrite and nitrate plus nitrite from processed meat. Results also suggested a positive association between red meat and PhIP and bladder carcinogenesis. © 2010 American Cancer Society.

Meat and components of meat and the risk of bladder cancer in the NIH-AARP Diet and Health Study

PubMed Central

Ferrucci, Leah M.; Sinha, Rashmi; Ward, Mary H.; Graubard, Barry I.; Hollenbeck, Albert R.; Kilfoy, Briseis A.; Schatzkin, Arthur; Michaud, Dominique S.; Cross, Amanda J.

2010-01-01

Background Meat could be involved in bladder carcinogenesis via multiple potentially carcinogenic meat-related compounds related to cooking and processing, including nitrate, nitrite, heterocyclic amines (HCAs), and polycyclic aromatic hydrocarbons. We comprehensively investigated the association between meat and meat components and bladder cancer. Methods During 7 years of follow-up, 854 transitional cell bladder cancer cases were identified among 300,933 men and women who completed a validated food frequency questionnaire in the large prospective NIH-AARP Diet and Health Study. We estimated intake of nitrate and nitrite from processed meat and HCAs and PAHs from cooked meat using quantitative databases of measured values. We calculated total dietary nitrate and nitrite based on literature values. Results The hazard ratios (HR) and 95% confidence intervals (CI) for red meat (HR for fifth compared to first quintile=1.22, 95% CI=0.96–1.54, p-trend=0.07) and the HCA 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) (HR=1.19, 95% CI=0.95–1.48, p-trend=0.06) conferred a borderline statistically significant increased risk of bladder cancer. We observed positive associations in the top quintile for total dietary nitrite (HR=1.28, 95% CI=1.02–1.61, p-trend= 0.06) and nitrate plus nitrite intake from processed meat (HR=1.29 95% CI=1.00–1.67, p-trend= 0.11). Conclusions These findings provide modest support for a role for total dietary nitrite and nitrate plus nitrite from processed meat in bladder cancer. Our results also suggest a positive association between red meat and PhIP and bladder carcinogenesis. PMID:20681011

Safer and healthier reduced nitrites turkey meat sausages using lyophilized Cystoseira barbata seaweed extract.

PubMed

Sellimi, Sabrine; Benslima, Abdelkarim; Ksouda, Ghada; Montero, Veronique Barragan; Hajji, Mohamed; Nasri, Moncef

2017-10-21

Background Nitrite salts are still common additives in the meat industry. The present study provides a first approach on the employment of the lyophilized aqueous extract (WE) of the Tunisian seaweed Cystoseira barbata for the quality enhancement of turkey meat sausage. Methods WE was supplemented as a natural antioxidant agent to investigate its effectiveness in delaying lipid oxidation turkey meat sausages containing reduced amounts of sodium nitrites. Results On storage day 5, all concentrations of WE (0.01-0.4 %) reduced the meat lipid oxidation by approximately 36 %, as compared to the negative control containing only 80 mg/kg of meat of sodium nitrites as antioxidant. It was noted that within 15 days of refrigerated storage, a meat system containing 80 mg/kg of meat of sodium nitrites and 0.02 % and 0.04 % of WE had similar Thiobarbituric Acid Reactive Substances (TBARS) levels (19±1.32 and 17±1.12 µmol/kg of meat, respectively), which were comparable to the positive control containing sodium nitrites (150 mg/kg of meat) and 0.045 % vitamin C (18.46±1.27 µmol/kg of meat). In-depth, the metabolomic profiling using gas chromatography-mass spectrometry (GC/MS) and liquid chromatography-quadripole-time-of-flight-mass spectrometry (LC-QTOF-MS) analyses of the Tunisian seaweed C. barbata solvent extracts showed that the main active compounds were phenolic compounds, fatty acids and sterols. Conclusions Overall, the cold medium containing C. barbata lyophilized aqueous extrac, with strong antioxidant activity and antihypertensive properties, may open the way to the development of a natural quality enhancement strategy for new functional and ever healthier reduced nitrites meat sausages based on algae.

Nitrite, nitrite alternatives, and the control of Clostridium botulinum in cured meats.

PubMed

Pierson, M D; Smoot, L A

1982-01-01

Historically, nitrite has been a component of meat-curing additives for several centuries. In recent years the safety of nitrite as an additive in cured meats has been questioned mainly because of the possible formation of carcinogenic nitrosamines. Nitrite has many important functions in meat curing including its role in color development, flavor, antioxidant properties, and antimicrobial activity. The inhibition of Clostridium botulinum growth and toxin production is an especially important antimicrobial property of nitrite. This review discusses the effects of processing, curing ingredients (especially nitrite), and storage of cured meats in relation to the control of C. botulinum. If nitrite is eliminated from cured meats or the level of usage decreased, then alternatives for the antibotulinal function of nitrite need to be considered. Several potential alternatives including sorbates, parabens, and biological acidulants are discussed.

Combined effects of high hydrostatic pressure and sodium nitrite on color, water holding capacity and texture of frankfurter

NASA Astrophysics Data System (ADS)

Jonas, G.; Csehi, B.; Palotas, P.; Toth, A.; Kenesei, Gy; Pasztor-Huszar, K.; Friedrich, L.

2017-10-01

The aim of this study was to investigate the effect of sodium nitrite and high hydrostatic pressure on the color, water holding capacity (WHC) and texture characteristics of frankfurter. Three hundred, 450 and 600 MPa (5 minutes; 20 °C) and 50, 75, 100 and 125 ppm (calculated on weight of meat) sodium nitrite were applied. Parameters were measured right after the pressure treatment. Data were evaluated with two-way analysis of variance (p 0.05) with pressure levels and sodium nitrite amounts as factors. Nitrite reduction significantly increased lightness (L*) and resulted in decreased redness (a*) value. The pressure treatments decreased the lightness at all nitrite concentrations and did not significantly affect the red color of frankfurters. Fifty and 75 ppm nitrite and pressurization at 300 or 450 MPa improved the water holding property of frankfurter. The pressure treatment did not significantly affect the WHC but changing the nitrite amount had significant effect on it. Interactive effect occurred between pressure levels and nitrite concentrations for hardness. The pressure treatment increased and the nitrite reduction decreased hardness. Significant changes were found in cohesiveness at 450 and 600 MPa in frankfurters containing 50 and 75 ppm nitrite: pressure treatment at higher levels and nitrite reduction decreased the value of cohesiveness.

Nitrogen removal via nitrite from seawater contained sewage.

PubMed

Peng, Yongzhen; Yu, De-Shuang; Liang, Dawei; Zhu, Guibing

2004-01-01

Under the control of both pH and the concentration of free ammonia (FA), the nitrification-denitrification via nitrite pathway was accomplished in SBR to achieve enhanced biological nitrogen removal from seawater contained wastewater, which is used to flush toilet, under relatively high salinity. Several parameters including salinity, temperature, pH, and NH4+-N loading rate were studied to evaluate their effects. The results indicate that at different salinity the nitrogen removal efficiency is relative to ammonia-nitrogen loading rate. The nitrogen removal efficiency reaches above 90% when the NH4+-N loading does not exceed 0.15 kg NH4+-N/kg MLSS d. With the salinity increasing, the ammonia-nitrogen loading rate should be lowered to obtain high removal efficiency. The evaluation of temperature effect shows that nitrogen removal efficiency is promoted twice when reaction temperature is elevated from 20 to 30 degrees C. Moderately high pH in the range of 7.5-8.5 has advantage to achieve effective nitrification-denitrification via nitrite, the process of which is caused by the selective inhibition of free ammonia (FA).

Molecular Characterization of Lactobacillus plantarum DMDL 9010, a Strain with Efficient Nitrite Degradation Capacity

PubMed Central

Fei, Yong-tao; Liu, Dong-mei; Luo, Tong-hui; Chen, Gu; Wu, Hui; Li, Li; Yu, Yi-gang

2014-01-01

Nitrites commonly found in food, especially in fermented vegetables, are potential carcinogens. Therefore, limiting nitrites in food is critically important for food safety. A Lactobacillus strain (Lactobacillus sp. DMDL 9010) was previously isolated from fermented vegetables by our group, and is not yet fully characterized. A number of phenotypical and genotypical approaches were employed to characterize Lactobacillus sp. DMDL 9010. Its nitrite degradation capacity was compared with four other Lactobacillus strains, including Lactobacillus casei subsp. rhamnosus 719, Lactobacillus delbrueckii subsp. bulgaricu 1.83, Streptococcus thermophilus 1.204, and lactobacillus plantarum 8140, on MRS medium. Compared to these four Lactobacillus strains, Lactobacillus sp. DMDL 9010 had a significantly higher nitrite degradation capacity (P<0.001). Based on 16S rDNA sequencing and sequence comparison, Lactobacillus sp. DMDL 9010 was identified as either Lactobacillus plantarum or Lactobacillus pentosus. To further identify this strain, the flanking regions (922 bp and 806 bp upstream and downstream, respectively) of the L-lactate dehydrogenase 1 (L-ldh1) gene were amplified and sequenced. Lactobacillus sp. DMDL 9010 had 98.92 and 76.98% sequence identity in the upstream region with L. plantarum WCFS1 and L. pentosus IG1, respectively, suggesting that Lactobacillu sp. DMDL 9010 is an L. plantarum strain. It was therefore named L. plantarum DMDL 9010. Our study provides a platform for genetic engineering of L. plantarum DMDL 9010, in order to further improve its nitrite degradation capacity. PMID:25423449

Nitrite oxidizing bacteria for water treatment in coastal aquaculture system

NASA Astrophysics Data System (ADS)

Noorak, S.; Rakkhiaw, S.; Limjirakhajornt, K.; Uppabullung, A.; Keawtawee, T.; Sangnoi, Y.

2018-04-01

This research aimed to isolate and characterize nitrite oxidizing bacteria and to study their capability for water quality improvement. Fourteen strains of bacteria with nitrite-oxidizing character were isolated after 21 days of enrichment in Pep-Beef-NOB medium contained NaNO2. Two strains, SF-1 and SF-5, showed highest nitrite removal rate for 42.42% and 37.2%, respectively. These strains were determined an efficiency of open-system wastewater treatment for 14 days. The results showed that control, SF-1 and SF-5 had remove ammonia from day 1 to day 6. At the end of the study, ammonia was removed by the control, SF-1 and SF-5 for 81.27%, 70.1% and 69.82%, respectively. Nitrite concentration was lowest at day 8 with removal rate of 98.73%, 98.3% and 97.24% from control, SF-1 and SF-5, respectively. However, nitrite concentration in control experiment was increased again at day 11 whereas in SF-1 and SF-5 were increased at day 13. Chemical Oxygen Demand (COD) was decreased by 77.78%, 73.50% and 78.63% in the control, SF-1 and SF-5, respectively. Biological Oxygen Demand (BOD) in the control, SF-1 and SF-5 were reduced by 85.92%, 79.53% and 82.09%, respectively. Based on 16S rRNA gene, SF-1 and SF-5 were identified as Bacillus vietnamensis and B. firmus, respectively.

Molecular characterization of Lactobacillus plantarum DMDL 9010, a strain with efficient nitrite degradation capacity.

PubMed

Fei, Yong-tao; Liu, Dong-mei; Luo, Tong-hui; Chen, Gu; Wu, Hui; Li, Li; Yu, Yi-gang

2014-01-01

Nitrites commonly found in food, especially in fermented vegetables, are potential carcinogens. Therefore, limiting nitrites in food is critically important for food safety. A Lactobacillus strain (Lactobacillus sp. DMDL 9010) was previously isolated from fermented vegetables by our group, and is not yet fully characterized. A number of phenotypical and genotypical approaches were employed to characterize Lactobacillus sp. DMDL 9010. Its nitrite degradation capacity was compared with four other Lactobacillus strains, including Lactobacillus casei subsp. rhamnosus 719, Lactobacillus delbrueckii subsp. bulgaricu 1.83, Streptococcus thermophilus 1.204, and lactobacillus plantarum 8140, on MRS medium. Compared to these four Lactobacillus strains, Lactobacillus sp. DMDL 9010 had a significantly higher nitrite degradation capacity (P<0.001). Based on 16S rDNA sequencing and sequence comparison, Lactobacillus sp. DMDL 9010 was identified as either Lactobacillus plantarum or Lactobacillus pentosus. To further identify this strain, the flanking regions (922 bp and 806 bp upstream and downstream, respectively) of the L-lactate dehydrogenase 1 (L-ldh1) gene were amplified and sequenced. Lactobacillus sp. DMDL 9010 had 98.92 and 76.98% sequence identity in the upstream region with L. plantarum WCFS1 and L. pentosus IG1, respectively, suggesting that Lactobacillu sp. DMDL 9010 is an L. plantarum strain. It was therefore named L. plantarum DMDL 9010. Our study provides a platform for genetic engineering of L. plantarum DMDL 9010, in order to further improve its nitrite degradation capacity.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cohen, Michael F.; Gurung, Sushma; Birarda, Giovanni

In the genus Azolla rapid abscission of roots from floating fronds occurs within minutes in response to a variety of stresses, including exposure to nitrite. We found that hydrogen peroxide, though itself not an inducer of root abscission, modulates nitrite-induced root abscission by Azolla pinnata in a dose-dependent manner, with 2 mM H 2O 2 significantly diminishing the responsiveness to 2 mM NaNO 2, and 10 mM H 2O 2 slightly enhancing it. Hypoxia, which has been found in other plants to result in autogenic production of H 2O 2, dramatically stimulated root abscission of A. pinnata in response tomore » nitrite, especially for plants previously cultivated in medium containing 5 mM KNO 3 compared to plants cultivated under N 2-fixing conditions without combined nitrogen. Plants, including Azolla, produce the small signaling molecule nitric oxide (NO) from nitrite using nitrate reductase. We found Azolla plants to display dose-dependent root abscission in response to the NO donor spermine NONOate. Treatment of plants with the thiol-modifying agents S-methyl methanethiosulfonate or glutathione inhibited the nitrite-induced root abscission response. Synchrotron radiation-based Fourier transform infrared spectromicroscopy revealed higher levels of carbonylation in the abscission zone of dropped roots, indicative of reaction products of polysaccharides with potent free radical oxidants. Lastly, we hypothesize that metabolic products of nitrite and NO react with H 2O 2 in the apoplast leading to free-radical-mediated cleavage of structural polysaccharides and consequent rapid root abscission.« less

Nitrite toxicity to the crayfish Procambarus clarkii

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gutzmer, M.P.; Tomasso, J.R.

The purpose of this study was to determine the effects of acute nitrite exposure to the crayfish Procambarus clarkii (Decapoda). Specific objectives of this study included (1) determining the 24-, 48-, 72- and 96-h LC-50's of nitrite to crayfish of different weights and genders in freshwater, (2) determining the LC-50's of nitrite to crayfish in water with elevated chloride concentrations, and (3), in order to gain insight into the mechanisms of nitrite toxicity in crayfish, determining hemolymph nitrite concentrations in crayfish exposed to nitrite in freshwater and water with elevated chloride concentrations.

DFT Study on Nitrite Reduction Mechanism in Copper-Containing Nitrite Reductase.

PubMed

Lintuluoto, Masami; Lintuluoto, Juha M

2016-01-12

Dissimilatory reduction of nitrite by copper-containing nitrite reductase (CuNiR) is an important step in the geobiochemical nitrogen cycle. The proposed mechanisms for the reduction of nitrite by CuNiRs include intramolecular electron and proton transfers, and these two events are understood to couple. Proton-coupled electron transfer is one of the key processes in enzyme reactions. We investigated the geometric structure of bound nitrite and the mechanism of nitrite reduction on CuNiR using density functional theory calculations. Also, the proton transfer pathway, the key residues, and their roles in the reaction mechanism were clarified in this study. In our results, the reduction of T2 Cu site promotes the proton transfer, and the hydrogen bond network around the binding site has an important role not only to stabilize the nitrite binding but also to promote the proton transfer to nitrite.

Changes in plasma and urinary nitrite after birth in premature infants at risk for necrotizing enterocolitis

PubMed Central

Pun, Priti; Jones, Jesica; Wolfe, Craig; Deming, Douglas D.; Power, Gordon G.; Blood, Arlin B.

2016-01-01

Background Plasma nitrite serves as a reservoir of nitric oxide (NO) bioactivity. Because nitrite ingestion is markedly lower in newborns than adults, we hypothesized plasma nitrite levels would be lower in newborns than in adults, and that infants diagnosed with necrotizing enterocolitis (NEC), a disease characterized by ischemia and bacterial invasion of intestinal walls, would have lower levels of circulating nitrite in the days prior to diagnosis. Methods Single blood and urine samples were collected from 9 term infants and 12 adults, 72 preterm infants every 5 d for 3 wk, and from 13 lambs before and after cord occlusion. Results Nitrite fell 50% relative to cord levels in the first day after birth; and within 15 min after cord occlusion in lambs. Urinary nitrite was higher in infants than adults. Plasma and urinary nitrite levels in infants who developed NEC were similar to those of preterm control infants on days 1 and 5, but significantly elevated at 15 and 20 d after birth. Conclusion Plasma nitrite falls dramatically at birth while newborn urinary nitrite levels are significantly greater than adults. Acute NEC is associated with elevated plasma and urinary nitrite levels. PMID:26539663

Nitrite transport into pig erythrocytes and its potential biological role.

PubMed

Jensen, F B

2005-07-01

To study nitrite transport and its oxygenation dependency in pig erythrocytes, as this is fundamental to the possible participation of nitrite in blood flow regulation via its reduction to nitric oxide by deoxygenated haemoglobin (Hb). Pig red blood cells (RBCs) were tonometer-equilibrated to physiological pCO2 in oxygenated and deoxygenated states. Nitrite was added and the kinetics of NO2- influx and methaemoglobin (metHb) formation were assessed at variable temperature and haematocrit. Nitrite quickly permeated and equilibrated across the membrane, and then continued to enter RBCs as a consequence of its intracellular removal (via reactions with Hb to form nitrate and metHb in oxygenated cells, and NO and metHb in deoxygenated cells). The membrane permeation as such showed little oxygenation dependency, but as metHb formation was significantly higher in oxygenated than deoxygenated RBCs, nitrite transport tended to be largest into oxygenated RBCs. This contrasts with a preferential permeation of deoxygenated RBCs in some fish species. Nitrite transport showed low temperature sensitivity but was speeded up at low haematocrit via more rapid intracellular nitrite removal (metHb formation). Nitrite influx was not affected by inhibitors of facilitated diffusion (DIDS, phloretin and PCMB) and may occur via conductive transport. Extracellular pH was stable during nitrite transport. Nitrite extensively permeates both oxygenated and deoxygenated pig RBCs, which may enable a dual function of nitrite entry: viz. conversion to NO at low pO2 to promote blood flow and detoxification to non-toxic nitrate at inappropriate high nitrite levels.

Nitrite oxidation in the Namibian oxygen minimum zone

PubMed Central

Füssel, Jessika; Lam, Phyllis; Lavik, Gaute; Jensen, Marlene M; Holtappels, Moritz; Günter, Marcel; Kuypers, Marcel MM

2012-01-01

Nitrite oxidation is the second step of nitrification. It is the primary source of oceanic nitrate, the predominant form of bioavailable nitrogen in the ocean. Despite its obvious importance, nitrite oxidation has rarely been investigated in marine settings. We determined nitrite oxidation rates directly in 15N-incubation experiments and compared the rates with those of nitrate reduction to nitrite, ammonia oxidation, anammox, denitrification, as well as dissimilatory nitrate/nitrite reduction to ammonium in the Namibian oxygen minimum zone (OMZ). Nitrite oxidation (⩽372 nM NO2− d−1) was detected throughout the OMZ even when in situ oxygen concentrations were low to non-detectable. Nitrite oxidation rates often exceeded ammonia oxidation rates, whereas nitrate reduction served as an alternative and significant source of nitrite. Nitrite oxidation and anammox co-occurred in these oxygen-deficient waters, suggesting that nitrite-oxidizing bacteria (NOB) likely compete with anammox bacteria for nitrite when substrate availability became low. Among all of the known NOB genera targeted via catalyzed reporter deposition fluorescence in situ hybridization, only Nitrospina and Nitrococcus were detectable in the Namibian OMZ samples investigated. These NOB were abundant throughout the OMZ and contributed up to ∼9% of total microbial community. Our combined results reveal that a considerable fraction of the recently recycled nitrogen or reduced NO3− was re-oxidized back to NO3− via nitrite oxidation, instead of being lost from the system through the anammox or denitrification pathways. PMID:22170426

Trends In Nutrient and Sediment Concentrations and Loads In Major River Basins of the South-Central United States, 1993-2004

USGS Publications Warehouse

Rebich, Richard A.; Demcheck, Dennis K.

2008-01-01

Nutrient and sediment data collected at 115 sites by Federal and State agencies from 1993 to 2004 were analyzed by the U.S. Geological Survey to determine trends in concentrations and loads for selected rivers and streams that drain into the northwestern Gulf of Mexico from the south-central United States, specifically from the Lower Mississippi, Arkansas-White-Red, and Texas-Gulf Basins. Trends observed in the study area were compared to determine potential regional patterns and to determine cause-effect relations with trends in hydrologic and human-induced factors such as nutrient sources, streamflow, and implementation of best management practices. Secondary objectives included calculation of loads and yields for the study period as a basis for comparing the delivery of nutrients and sediment to the northwestern Gulf of Mexico from the various rivers within the study area. In addition, loads were assessed at seven selected sites for the period 1980-2004 to give hydrologic perspective to trends in loads observed during 1993-2004. Most study sites (about 64 percent) either had no trends or decreasing trends in streamflow during the study period. The regional pattern of decreasing trends in streamflow during the study period appeared to correspond to moist conditions at the beginning of the study period and the influence of three drought periods during the study period, of which the most extreme was in 2000. Trend tests were completed for ammonia at 49 sites, for nitrite plus nitrate at 69 sites, and for total nitrogen at 41 sites. For all nitrogen constituents analyzed, no trends were observed at half or more of the sites. No regional trend patterns could be confirmed because there was poor spatial representation of the trend sites. Decreasing trends in flow-adjusted concentrations of ammonia were observed at 25 sites. No increasing trends in concentrations of ammonia were noted at any sites. Flow-adjusted concentrations of nitrite plus nitrate decreased at 7 sites and increased at14 sites. Flow-adjusted concentrations of total nitrogen decreased at 2 sites and increased at 12 sites. Improvements to municipal wastewater treatment facilities contributed to the decline of ammonia concentrations at selected sites. Notable increasing trends in nitrite plus nitrate and total nitrogen at selected study sites were attributed to both point and nonpointsources. Trend patterns in total nitrogen generally followed trend patterns in nitrite plus nitrate, which was understandable given that nitrite plus nitrate loads generally were 70-90 percent of the total nitrogen loads at most sites. Population data were used as a surrogate to understand the relation between changes in point sources and nutrient trends because data from wastewater treatment plants were inconsistent for this study area. Although population increased throughout the study area during the study period, there was no observed relation between increasing trends in nitrogen in study area streams and increasing trends in population. With respect to other nitrogen sources, statistical results did suggest that increasing trends in nitrogen could be related to increasing trends in nitrogen from either commercial fertilizer use and/or land application of manure. Loads of ammonia, nitrite plus nitrate, and total nitrogen decreased during the study period, but some trends in nitrogen loads were part of long-term decreases since 1980. For example, ammonia loads were shown to decrease at nearly all sites over the past decade, but at selected sites, these decreasing trends were part of much longer trends since 1980. The Mississippi and Atchafalaya Rivers contributed the highest nitrogen loads to the northwestern Gulf of Mexico as expected; however, nitrogen yields from smaller rivers had similar or higher yields than yields from the Mississippi River. Trend tests were completed for orthophosphorus at 34 sites and for total phosphorus at 52 sites. No trends were observed in abo

Retention and leaching of nitrite by municipal solid waste incinerator bottom ash under the landfill circumstance.

PubMed

Yao, Jun; Kong, Qingna; Zhu, Huayue; Long, Yuyang; Shen, Dongsheng

2015-01-01

The retention and leaching of nitrite by municipal solid waste incinerator (MSWI) bottom ash could affect its migration in the landfill. In this study, the effect of the dosage of MSWI bottom ash as well as the variation of the landfill environmental parameters including pH, anions and organic matter on the nitrite retention and leaching behavior was investigated by batch experiments. The highest removal percentage (73.0%) of nitrite was observed when the dosage of MSWI bottom ash was 10 g L(-1) in 2 mg L(-1) nitrite solution. Further increase of the dosage would retard the retention, as the nitrite leaching from MSWI bottom ash was enhanced. The optimum retention of nitrite was observed when the pH was 5.0, while the leaching of nitrite showed a consistent reduction with the increase of pH. Besides, the presence of Cl(-), SO4(2)(-) and acetic acid could enhance the leaching of nitrite and mitigate the retention process. However, the retention of nitrite was enhanced by PO4(3)(-), which was probably due to the formation of the apatite, an active material for the adsorption of the nitrite. These results suggested that MSWI bottom ash could affect the migration of nitrite in the landfill, which was related to the variation of the landfill circumstance. Copyright © 2014 Elsevier Ltd. All rights reserved.

21 CFR 170.60 - Nitrites and/or nitrates in curing premixes.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Nitrites and/or nitrates in curing premixes. 170... and Decisions § 170.60 Nitrites and/or nitrates in curing premixes. (a) Nitrites and/or nitrates are.... (b) Nitrites and/or nitrates, when packaged separately from flavoring and seasoning in curing...

21 CFR 170.60 - Nitrites and/or nitrates in curing premixes.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Nitrites and/or nitrates in curing premixes. 170... and Decisions § 170.60 Nitrites and/or nitrates in curing premixes. (a) Nitrites and/or nitrates are.... (b) Nitrites and/or nitrates, when packaged separately from flavoring and seasoning in curing...

21 CFR 170.60 - Nitrites and/or nitrates in curing premixes.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Nitrites and/or nitrates in curing premixes. 170... and Decisions § 170.60 Nitrites and/or nitrates in curing premixes. (a) Nitrites and/or nitrates are.... (b) Nitrites and/or nitrates, when packaged separately from flavoring and seasoning in curing...

The use of atmospheric pressure plasma-treated water as a source of nitrite for emulsion-type sausage.

PubMed

Jung, Samooel; Kim, Hyun Joo; Park, Sanghoo; In Yong, Hae; Choe, Jun Ho; Jeon, Hee-Joon; Choe, Wonho; Jo, Cheorun

2015-10-01

We investigated the possible use of atmospheric pressure plasma-treated water (PTW) as a nitrite source in curing process. Emulsion-type sausages were manufactured with PTW, celery powder containing nitrite, and synthetic sodium nitrite at a concentration of nitrite ion 70mgkg(-1). In terms of sausage quality, there were no noticeable effects of PTW on the total aerobic bacterial counts, color, and peroxide values of sausages compared with those of celery powder and sodium nitrite throughout 28days of storage at 4°C. Sausage with added PTW had lower concentrations of residual nitrite compared to those of added celery powder and sodium nitrite during the storage period (P<0.05). The sensory properties of PTW-treated and sodium nitrite-treated sausages were not different, whereas the sausage with added celery powder received the lowest scores in taste and acceptability. From the results, it is concluded that PTW can be used as a nitrite source equivalent to a natural curing agent. Copyright © 2015 Elsevier Ltd. All rights reserved.

Total salivary nitrates and nitrites in oral health and periodontal disease.

PubMed

Sánchez, Gabriel A; Miozza, Valeria A; Delgado, Alejandra; Busch, Lucila

2014-01-30

It is well known that nitrites are increased in saliva from patients with periodontal disease. In the oral cavity, nitrites may derive partly from the reduction of nitrates by oral bacteria. Nitrates have been reported as a defence-related mechanism. Thus, the aim of the present study was to determine the salivary levels of total nitrate and nitrite and their relationship, in unstimulated and stimulated saliva from periodontal healthy subjects, and from patients with chronic periodontal disease. Nitrates and nitrites were determined in saliva from thirty healthy subjects and forty-four patients with periodontal disease. A significant increase in salivary nitrates and nitrites was observed. Nitrates and nitrites concentration was related to clinical attachment level (CAL). A positive and significant Pearson's correlation was found between salivary total nitrates and nitrites. Periodontal treatment induced clinical improvement and decreased nitrates and nitrites. It is concluded that salivary nitrates and nitrites increase, in patients with periodontal disease, could be related to defence mechanisms. The possibility that the salivary glands respond to oral infectious diseases by increasing nitrate secretion should be explored further. Copyright © 2013 Elsevier Inc. All rights reserved.

Recommendation of ruthenium source for sludge batch flowsheet studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Woodham, W.

Included herein is a preliminary analysis of previously-generated data from sludge batches 7a, 7b, 8, and 9 sludge simulant and real-waste testing, performed to recommend a form of ruthenium for future sludge batch simulant testing under the nitric-formic flowsheet. Focus is given to reactions present in the Sludge Receipt and Adjustment Tank cycle, given that this cycle historically produces the most changes in chemical composition during Chemical Process Cell processing. Data is presented and analyzed for several runs performed under the nitric-formic flowsheet, with consideration given to effects on the production of hydrogen gas, nitrous oxide gas, consumption of formate,more » conversion of nitrite to nitrate, and the removal and recovery of mercury during processing. Additionally, a brief discussion is given to the effect of ruthenium source selection under the nitric-glycolic flowsheet. An analysis of data generated from scaled demonstration testing, sludge batch 9 qualification testing, and antifoam degradation testing under the nitric-glycolic flowsheet is presented. Experimental parameters of interest under the nitric-glycolic flowsheet include N2O production, glycolate destruction, conversion of glycolate to formate and oxalate, and the conversion of nitrite to nitrate. To date, the number of real-waste experiments that have been performed under the nitric-glycolic flowsheet is insufficient to provide a complete understanding of the effects of ruthenium source selection in simulant experiments with regard to fidelity to real-waste testing. Therefore, a determination of comparability between the two ruthenium sources as employed under the nitric-glycolic flowsheet is made based on available data in order to inform ruthenium source selection for future testing under the nitric-glycolic flowsheet.« less

Vibration-based photoacoustic tomography

NASA Astrophysics Data System (ADS)

Li, Rui; Rajian, Justin R.; Wang, Pu; Slipchenko, Mikhail N.; Cheng, Ji-Xin

2013-03-01

Photoacoustic imaging employing molecular overtone vibration as contrast mechanism opens a new avenue for deep tissue imaging with chemical bond selectivity. Here, we demonstrate vibration-based photoacoustic tomography with an imaging depth on the centimeter scale. To provide sufficient pulse energy at the overtone transition wavelengths, we constructed a compact, barium nitrite crystal-based Raman laser for excitation of 2nd overtone of C-H bond. Using a 5-ns Nd:YAG laser as pumping source, up to 105 mJ pulse energy at 1197 nm was generated. Vibrational photoacoutic spectroscopy and tomography of phantom (polyethylene tube) immersed in whole milk was performed. With a pulse energy of 47 mJ on the milk surface, up to 2.5 cm penetration depth was reached with a signal-to-noise ratio of 12.

Bare and boron-doped cubic silicon carbide nanowires for electrochemical detection of nitrite sensitively

PubMed Central

Yang, Tao; Zhang, Liqin; Hou, Xinmei; Chen, Junhong; Chou, Kuo-Chih

2016-01-01

Fabrication of eletrochemical sensors based on wide bandgap compound semiconductors has attracted increasing interest in recent years. Here we report for the first time electrochemical nitrite sensors based on cubic silicon carbide (SiC) nanowires (NWs) with smooth surface and boron-doped cubic SiC NWs with fin-like structure. Multiple techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and electron energy loss spectroscopy (EELS) were used to characterize SiC and boron-doped SiC NWs. As for the electrochemical behavior of both SiC NWs electrode, the cyclic voltammetric results show that both SiC electrodes exhibit wide potential window and excellent electrocatalytic activity toward nitrite oxidation. Differential pulse voltammetry (DPV) determination reveals that there exists a good linear relationship between the oxidation peak current and the concentration in the range of 50–15000 μmoL L−1 (cubic SiC NWs) and 5–8000 μmoL L−1 (B-doped cubic SiC NWs) with the detection limitation of 5 and 0.5 μmoL L−1 respectively. Compared with previously reported results, both as-prepared nitrite sensors exhibit wider linear response range with comparable high sensitivity, high stability and reproducibility. PMID:27109361

Oral nitrite circumvents antiseptic mouthwash-induced disruption of enterosalivary circuit of nitrate and promotes nitrosation and blood pressure lowering effect.

PubMed

Pinheiro, Lucas C; Ferreira, Graziele C; Amaral, Jefferson H; Portella, Rafael L; Tella, Sandra de O C; Passos, Madla A; Tanus-Santos, Jose E

2016-12-01

The nitric oxide (NO • ) metabolites nitrite and nitrate exert antihypertensive effects by mechanisms that involve gastric formation of S-nitrosothiols. However, while the use of antiseptic mouthwash (AM) is known to attenuate the responses to nitrate by disrupting its enterosalivary cycle, there is little information about whether AM attenuates the effects of orally administered nitrite. We hypothesized that the antihypertensive effects of orally administered nitrite would not be prevented by AM because, in contrast to oral nitrate, oral nitrite could promote S-nitrosothiols formation in the stomach without intereference by AM. Chronic effects of oral nitrite or nitrate were studied in two-kidney, one-clip (2K1C) hypertensive rats (and normotensive controls) treated with AM (or vehicle) once/day. We found that orally administered nitrite exerts antihypertensive effects that were not affected by AM. This finding contrasts with lack of antihypertensive responses to oral nitrate in 2K1C hypertensive rats treated with AM. Nitrite and nitrate treatments increased plasma nitrites, nitrates, and S-nitrosothiols concentrations. However, while treatment with AM attenuated the increases in plasma nitrite concentrations after both nitrite and nitrate treatments, AM attenuated the increases in S-nitrosothiols in nitrate-treated rats, but not in nitrite-treated rats. Moreover, AM attenuated vascular S-nitrosylation (detected by the SNO-RAC method) after nitrate, but not after nitrite treatment. Significant correlations were found between the hypotensive responses and S-nitrosothiols, and vascular S-nitrosylation levels. These results show for the first time that oral nitrite exerts antihypertensive effects notwithstanding the fact that antiseptic mouthwash disrupts the enterosalivary circulation of nitrate. Our results support a major role for S-nitrosothiols formation resulting in vascular S-nitrosylation as a key mechanism for the antihypertensive effects of both oral nitrite and nitrate. Copyright © 2016 Elsevier Inc. All rights reserved.

Construction of a zinc porphyrin-fullerene-derivative based nonenzymatic electrochemical sensor for sensitive sensing of hydrogen peroxide and nitrite.

PubMed

Wu, Hai; Fan, Suhua; Jin, Xiaoyan; Zhang, Hong; Chen, Hong; Dai, Zong; Zou, Xiaoyong

2014-07-01

Enzymatic sensors possess high selectivity but suffer from some limitations such as instability, complicated modified procedure, and critical environmental factors, which stimulate the development of more sensitive and stable nonenzymatic electrochemical sensors. Herein, a novel nonenzymatic electrochemical sensor is proposed based on a new zinc porphyrin-fullerene (C60) derivative (ZnP-C60), which was designed and synthesized according to the conformational calculations and the electronic structures of two typical ZnP-C60 derivatives of para-ZnP-C60 (ZnP(p)-C60) and ortho-ZnP-C60 (ZnP(o)-C60). The two derivatives were first investigated by density functional theory (DFT) and ZnP(p)-C60 with a bent conformation was verified to possess a smaller energy gap and better electron-transport ability. Then ZnP(p)-C60 was entrapped in tetraoctylammonium bromide (TOAB) film and modified on glassy carbon electrode (TOAB/ZnP(p)-C60/GCE). The TOAB/ZnP(p)-C60/GCE showed four well-defined quasi-reversible redox couples with extremely fast direct electron transfer and excellent nonenzymatic sensing ability. The electrocatalytic reduction of H2O2 showed a wide linear range from 0.035 to 3.40 mM, with a high sensitivity of 215.6 μA mM(-1) and a limit of detection (LOD) as low as 0.81 μM. The electrocatalytic oxidation of nitrite showed a linear range from 2.0 μM to 0.164 mM, with a sensitivity of 249.9 μA mM(-1) and a LOD down to 1.44 μM. Moreover, the TOAB/ZnP(p)-C60/GCE showed excellent stability and reproducibility, and good testing recoveries for analysis of the nitrite levels of river water and rainwater. The ZnP(p)-C60 can be used as a novel material for the fabrication of nonenzymatic electrochemical sensors.

Ammonification in Bacillus subtilis Utilizing Dissimilatory Nitrite Reductase Is Dependent on resDE

PubMed Central

Hoffmann, Tamara; Frankenberg, Nicole; Marino, Marco; Jahn, Dieter

1998-01-01

During anaerobic nitrate respiration Bacillus subtilis reduces nitrate via nitrite to ammonia. No denitrification products were observed. B. subtilis wild-type cells and a nitrate reductase mutant grew anaerobically with nitrite as an electron acceptor. Oxygen-sensitive dissimilatory nitrite reductase activity was demonstrated in cell extracts prepared from both strains with benzyl viologen as an electron donor and nitrite as an electron acceptor. The anaerobic expression of the discovered nitrite reductase activity was dependent on the regulatory system encoded by resDE. Mutation of the gene encoding the regulatory Fnr had no negative effect on dissimilatory nitrite reductase formation. PMID:9422613

Color Developing Capacity of Plasma-treated Water as a Source of Nitrite for Meat Curing.

PubMed

Jung, Samooel; Kim, Hyun Joo; Park, Sanghoo; Yong, Hae In; Choe, Jun Ho; Jeon, Hee-Joon; Choe, Wonho; Jo, Cheorun

2015-01-01

The interaction of plasma with liquid generates nitrogen species including nitrite (NO(-) 2). Therefore, the color developing capacity of plasma-treated water (PTW) as a nitrite source for meat curing was investigated in this study. PTW, which is generated by surface dielectric barrier discharge in air, and the increase of plasma treatment time resulted in increase of nitrite concentration in PTW. The PTW used in this study contains 46 ppm nitrite after plasma treatment for 30 min. To evaluate the effect of PTW on the cured meat color, meat batters were prepared under three different conditions (control, non-cured meat batter; PTW, meat batter cured with PTW; Sodium nitrite, meat batter cured with sodium nitrite). The meat batters were vacuum-packaged and cooked in a water-bath at 80℃ for 30 min. The typical color of cured meat developed in cooked meat batter treated with sodium nitrite or PTW. The lightness (L*) and yellowness (b*) values were similar in all conditions, whereas, the redness (a*) values of cooked meat batter with PTW and sodium nitrite (p<0.05) were significantly higher than the control. These data indicate that PTW can be used as a nitrite source in the curing process of meat without addition of other nitrite sources.

Color Developing Capacity of Plasma-treated Water as a Source of Nitrite for Meat Curing

PubMed Central

Jung, Samooel; Kim, Hyun Joo; Park, Sanghoo; Choe, Jun Ho; Jeon, Hee-Joon; Choe, Wonho

2015-01-01

The interaction of plasma with liquid generates nitrogen species including nitrite (NO−2). Therefore, the color developing capacity of plasma-treated water (PTW) as a nitrite source for meat curing was investigated in this study. PTW, which is generated by surface dielectric barrier discharge in air, and the increase of plasma treatment time resulted in increase of nitrite concentration in PTW. The PTW used in this study contains 46 ppm nitrite after plasma treatment for 30 min. To evaluate the effect of PTW on the cured meat color, meat batters were prepared under three different conditions (control, non-cured meat batter; PTW, meat batter cured with PTW; Sodium nitrite, meat batter cured with sodium nitrite). The meat batters were vacuum-packaged and cooked in a water-bath at 80℃ for 30 min. The typical color of cured meat developed in cooked meat batter treated with sodium nitrite or PTW. The lightness (L*) and yellowness (b*) values were similar in all conditions, whereas, the redness (a*) values of cooked meat batter with PTW and sodium nitrite (p<0.05) were significantly higher than the control. These data indicate that PTW can be used as a nitrite source in the curing process of meat without addition of other nitrite sources. PMID:26761900

Monitoring nitrite and nitrate residues in frankfurters during processing and storage.

PubMed

Pérez-Rodríguez, M L; Bosch-Bosch, N; Garciá-Mata, M

1996-09-01

Frankfurter-type sausages were prepared in a pilot plant with different concentrations of NaNO(2) (75, 125 or 250 ppm) combined or not with 200 ppm KNO(3). A meat system, free of curing agents, was also used as control. Nitrite and nitrate levels were tested in various processing steps and over 120 days storage at 3 °C of the vacuum-packaged frankfurters. Little influence of the originally added nitrite level on the amount of nitrate formed was observed. Important losses of nitrite and nitrate were due to cooking. Thereafter about 50% of the nitrite added initially remained in this form in all samples (39, 59 and 146 ppm, respectively) and between 10 and 15% as nitrate. When only nitrate was initially added, formation of nitrite after cooking was observed (maximum level 43 ppm NaNO(2)). Formulations prepared with both nitrate and nitrite showed no significant differences (p < 0.01) respect to their nitrite or nitrate counterparts. A good correlation among nitrite and nitrate levels and storage time was showed by multiple linear regression analysis. It is concluded that the use of nitrate in combination with nitrite in cooked meat products seems to have little technological significance and adds to the total body burden of nitrite.

Mechanisms of Human Erythrocytic Bioactivation of Nitrite*

PubMed Central

Liu, Chen; Wajih, Nadeem; Liu, Xiaohua; Basu, Swati; Janes, John; Marvel, Madison; Keggi, Christian; Helms, Christine C.; Lee, Amber N.; Belanger, Andrea M.; Diz, Debra I.; Laurienti, Paul J.; Caudell, David L.; Wang, Jun; Gladwin, Mark T.; Kim-Shapiro, Daniel B.

2015-01-01

Nitrite signaling likely occurs through its reduction to nitric oxide (NO). Several reports support a role of erythrocytes and hemoglobin in nitrite reduction, but this remains controversial, and alternative reductive pathways have been proposed. In this work we determined whether the primary human erythrocytic nitrite reductase is hemoglobin as opposed to other erythrocytic proteins that have been suggested to be the major source of nitrite reduction. We employed several different assays to determine NO production from nitrite in erythrocytes including electron paramagnetic resonance detection of nitrosyl hemoglobin, chemiluminescent detection of NO, and inhibition of platelet activation and aggregation. Our studies show that NO is formed by red blood cells and inhibits platelet activation. Nitric oxide formation and signaling can be recapitulated with isolated deoxyhemoglobin. Importantly, there is limited NO production from erythrocytic xanthine oxidoreductase and nitric-oxide synthase. Under certain conditions we find dorzolamide (an inhibitor of carbonic anhydrase) results in diminished nitrite bioactivation, but the role of carbonic anhydrase is abrogated when physiological concentrations of CO2 are present. Importantly, carbon monoxide, which inhibits hemoglobin function as a nitrite reductase, abolishes nitrite bioactivation. Overall our data suggest that deoxyhemoglobin is the primary erythrocytic nitrite reductase operating under physiological conditions and accounts for nitrite-mediated NO signaling in blood. PMID:25471374

Effect of light on colour and reaction of nitrite in sliced pork bologna under different chilled storage temperatures.

PubMed

Carballo, J; Cavestany, M; Jiménez-Colmenero, F

1991-01-01

The effect of different lighting conditions (darkness and exposure to 1900 ± 100 lux) on colour stability, conversion of added nitrite (residual nitrite, nitrite converted to nitrate, nitroso heme pigments, and protein-bound nitrite) and oxidative rancidity (2-thiobarbituric acid index) in sliced, vacuum-packaged pork bologna as a function of storage temperature (0 ± 1°C and 7 ± 1°C) was studied. Colour (redness) losses over the storage period were more dependent upon photochemical processes than on thermal processes, and the action of temperature on colour was attributable to its effect on microbial growth, which in turn also affects oxygen availability. Conversion of nitrite into the different fractions studied was chiefly temperature-dependent, but exposure to light lowered the residual nitrite content. Nevertheless, the effect of illumination on the constant rate of residual nitrite depletion was dependent on the storage temperature. Recovery of the added nitrite, i.e. the total of the nitrite in all the fractions combined, was highly dependent upon fluctuations in the residual nitrite levels and varied over the storage period. Under the conditions of the experiment, photo-oxidation did not appear to be a determining factor in lipid oxidation. Copyright © 1991. Published by Elsevier Ltd.

Evaluating operating conditions for outcompeting nitrite oxidizers and maintaining partial nitrification in biofilm systems using biofilm modeling and Monte Carlo filtering.

PubMed

Brockmann, D; Morgenroth, E

2010-03-01

In practice, partial nitrification to nitrite in biofilms has been achieved with a range of different operating conditions, but mechanisms resulting in reliable partial nitrification in biofilms are not well understood. In this study, mathematical biofilm modeling combined with Monte Carlo filtering was used to evaluate operating conditions that (1) lead to outcompetition of nitrite oxidizers from the biofilm, and (2) allow to maintain partial nitrification during long-term operation. Competition for oxygen was found to be the main mechanism for displacing nitrite oxidizers from the biofilm, and preventing re-growth of nitrite oxidizers in the long-term. To maintain partial nitrification in the model, a larger oxygen affinity (i.e., smaller half saturation constant) for ammonium oxidizers compared to nitrite oxidizers was required, while the difference in maximum growth rate was not important for competition under steady state conditions. Thus, mechanisms for washout of nitrite oxidizing bacteria from biofilms are different from suspended cultures where the difference in maximum growth rate is a key mechanism. Inhibition of nitrite oxidizers by free ammonia was not required to outcompete nitrite oxidizers from the biofilm, and to maintain partial nitrification to nitrite. But inhibition by free ammonia resulted in faster washout of nitrite oxidizers. Copyright 2009 Elsevier Ltd. All rights reserved.

Spectrofluorimetric determination of 1,3,5-trinitro-1,3,5-triazacyclohexane (hexogen, RDX) as a nitramine type explosive.

PubMed

Lapat, A; Székelyhidi, L; Hornyák, I

1997-01-01

RDX is one of the most important military explosives. It is a component of some plastic explosives which are frequently used in terrorist attacks. Two fluorimetric methods have been described for the quantitative determination of RDX which are based on the detection of nitrite ions. After a basic decomposition of RDX the nitrite ion can be detected by reaction with 4-aminofluorescein and by reactions forming a lumogallion-gallium(III) complex. These fluorimetric methods have been compared to a photometric reaction (Griess reaction) for determination of nitrite ions. It has been found that the fluorimetric methods have a higher sensitivity than the photometric method and they have been used in a wider concentration range.

21 CFR 172.175 - Sodium nitrite.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Sodium nitrite. 172.175 Section 172.175 Food and... Preservatives § 172.175 Sodium nitrite. The food additive sodium nitrite may be safely used in or on specified... follows: (1) As a color fixative in smoked cured tunafish products so that the level of sodium nitrite...

21 CFR 172.175 - Sodium nitrite.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Sodium nitrite. 172.175 Section 172.175 Food and... Preservatives § 172.175 Sodium nitrite. The food additive sodium nitrite may be safely used in or on specified... follows: (1) As a color fixative in smoked cured tunafish products so that the level of sodium nitrite...

21 CFR 172.175 - Sodium nitrite.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Sodium nitrite. 172.175 Section 172.175 Food and... Preservatives § 172.175 Sodium nitrite. The food additive sodium nitrite may be safely used in or on specified... follows: (1) As a color fixative in smoked cured tunafish products so that the level of sodium nitrite...

21 CFR 172.175 - Sodium nitrite.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Sodium nitrite. 172.175 Section 172.175 Food and... Preservatives § 172.175 Sodium nitrite. The food additive sodium nitrite may be safely used in or on specified... follows: (1) As a color fixative in smoked cured tunafish products so that the level of sodium nitrite...

Effect of Nitrite and Nitrate on Toxin Production by Clostridium botulinum and on Nitrosamine Formation in Perishable Canned Comminuted Cured Meat

PubMed Central

Christiansen, L. N.; Johnston, R. W.; Kautter, D. A.; Howard, J. W.; Aunan, W. J.

1973-01-01

Comminuted ham was formulated with different levels of sodium nitrite and nitrate, inoculated with Clostridium botulinum, and pasteurized to an internal temperature of 68.5 C. When added to the meat, nitrite concentrations decreased, and cooking had little effect on them. Nitrite concentrations decreased more rapidly during storage at 27 than at 7 C; however they remained rather constant at formulated levels throughout the experiment at both incubation temperatures. The level of nitrite added to the meat greatly influenced growth and toxin production of C. botulinum. The concentration of nitrite necessary to effect complete inhibition was dependent on the inoculum level. With 90 C. botulinum spores/g of meat, botulinum toxin developed in samples formulated with 150 but not with 200 μg of nitrite per g of meat. At a spore level of 5,000/g, toxin was detected in samples with 400 but not with 500 μg of nitrite per g of the product incubated at 27 C. At lower concentrations of nitrite, growth was retarded at both spore levels. No toxin developed in samples incubated at 7 C. Nitrate showed a statistically significant inhibitory effect at a given nitrite level; however, the effect was insufficient to be of practical value. Analyses for 14 volatile nitrosamines from samples made with varying levels of nitrite and nitrate were negative at a detection level of 0.01 μg of nitrite or nitrate per g of meat. PMID:4572891

Increase in gastric pH reduces hypotensive effect of oral sodium nitrite in rats.

PubMed

Pinheiro, Lucas C; Montenegro, Marcelo F; Amaral, Jefferson H; Ferreira, Graziele C; Oliveira, Alisson M; Tanus-Santos, Jose E

2012-08-15

The new pathway nitrate-nitrite-nitric oxide (NO) has emerged as a physiological alternative to the classical enzymatic pathway for NO formation from l-arginine. Nitrate is converted to nitrite by commensal bacteria in the oral cavity and the nitrite formed is then swallowed and reduced to NO under the acidic conditions of the stomach. In this study, we tested the hypothesis that increases in gastric pH caused by omeprazole could decrease the hypotensive effect of oral sodium nitrite. We assessed the effects of omeprazole treatment on the acute hypotensive effects produced by sodium nitrite in normotensive and L-NAME-hypertensive free-moving rats. In addition, we assessed the changes in gastric pH and plasma levels of nitrite, NO(x) (nitrate+nitrite), and S-nitrosothiols caused by treatments. We found that the increases in gastric pH induced by omeprazole significantly reduced the hypotensive effects of sodium nitrite in both normotensive and L-NAME-hypertensive rats. This effect of omeprazole was associated with no significant differences in plasma nitrite, NO(x), or S-nitrosothiol levels. Our results suggest that part of the hypotensive effects of oral sodium nitrite may be due to its conversion to NO in the acidified environment of the stomach. The increase in gastric pH induced by treatment with omeprazole blunts part of the beneficial cardiovascular effects of dietary nitrate and nitrite. Copyright © 2012 Elsevier Inc. All rights reserved.

Insights on Alterations to the Rumen Ecosystem by Nitrate and Nitrocompounds

PubMed Central

Latham, Elizabeth A.; Anderson, Robin C.; Pinchak, William E.; Nisbet, David J.

2016-01-01

Nitrate and certain short chain nitrocompounds and nitro-oxy compounds are being investigated as dietary supplements to reduce economic and environmental costs associated with ruminal methane emissions. Thermodynamically, nitrate is a preferred electron acceptor in the rumen that consumes electrons at the expense of methanogenesis during dissimilatory reduction to an intermediate, nitrite, which is primarily reduced to ammonia although small quantities of nitrous oxide may also be produced. Short chain nitrocompounds act as direct inhibitors of methanogenic bacteria although certain of these compounds may also consume electrons at the expense of methanogenesis and are effective inhibitors of important foodborne pathogens. Microbial and nutritional consequences of incorporating nitrate into ruminant diets typically results in increased acetate production. Unlike most other methane-inhibiting supplements, nitrate decreases or has no effect on propionate production. The type of nitrate salt added influences rates of nitrate reduction, rates of nitrite accumulation and efficacy of methane reduction, with sodium and potassium salts being more potent than calcium nitrate salts. Digestive consequences of adding nitrocompounds to ruminant diets are more variable and may in some cases increase propionate production. Concerns about the toxicity of nitrate's intermediate product, nitrite, to ruminants necessitate management, as animal poisoning may occur via methemoglobinemia. Certain of the naturally occurring nitrocompounds, such as 3-nitro-1-propionate or 3-nitro-1-propanol also cause poisoning but via inhibition of succinate dehydrogenase. Typical risk management procedures to avoid nitrite toxicity involve gradually adapting the animals to higher concentrations of nitrate and nitrite, which could possibly be used with the nitrocompounds as well. A number of organisms responsible for nitrate metabolism in the rumen have been characterized. To date a single rumen bacterium is identified as contributing appreciably to nitrocompound metabolism. Appropriate doses of the nitrocompounds and nitrate, singly or in combination with probiotic bacteria selected for nitrite and nitrocompound detoxification activity promise to alleviate risks of toxicity. Further studies are needed to more clearly define benefits and risk of these technologies to make them saleable for livestock producers. PMID:26973609

Interactions of nitrite with catalase: Enzyme activity and reaction kinetics studies.

PubMed

Krych-Madej, Justyna; Gebicka, Lidia

2017-06-01

Catalase, a heme enzyme, which catalyzes decomposition of hydrogen peroxide to water and molecular oxygen, is one of the main enzymes of the antioxidant defense system of the cell. Nitrite, used as a food preservative has long been regarded as a harmful compound due to its ability to form carcinogenic nitrosamines. Recently, much evidence has been presented that nitrite plays a protective role as a nitric oxide donor under hypoxic conditions. In this work the effect of nitrite on the catalytic reactions of catalase was studied. Catalase was inhibited by nitrite, and this process was pH-dependent. IC 50 values varied from about 1μM at pH5.0 to about 150μM of nitrite at pH7.4. The presence of chloride significantly enhanced nitrite-induced catalase inhibition, in agreement with earlier observations. The kinetics of the reactions of nitrite with ferric catalase, its redox intermediate, Compound I, and catalase inactive form, Compound II, was also studied. Possible mechanisms of nitrite-induced catalase inhibition are analyzed and the biological consequences of the reactions of catalase with nitrite are discussed. Copyright © 2017 Elsevier Inc. All rights reserved.

Trace analysis of nitrite ions in environmental samples by using in-situ synthesized Zein biopolymeric nanoparticles as the novel green solid phase extractor.

PubMed

Hatamie, Amir; Nassiri, Mahmoud; Alivand, Meghdad Doust; Bhatnagar, Amit

2018-01-01

For the first time, a novel green method using Zein biopolymeric nanoparticles as a green dispersive solid-phase extractor is reported for the separation and preconcentration of trace amount of nitrite (NO 2 - ) ions in ppb levels. The Zein protein is a biodegradable hydrophobic plant protein that is obtained from corn and is composed of a number of hydrophobic amino acids. Zein bionanoparticles were synthesized in an anti-solvent process and used as a new biosorbent in the extraction technique. In the proposed technique, by using a standard method at first, a mixture of 1-naphthylamine and sulphanilic acid as selective regents was added to the samples, and in the presence of the nitrite ion, a red azo product was formed. After that, the ethanolic Zein solution (equal to 15mg) was injected rapidly into the sample, based on the anti-solvent process. Zein bionanoparticles (BNPs) were produced, the adsorbed colour product was separated by centrifugation, and finally samples were analysed with the spectrophotometric method. The influence of different variables such as pH, buffer and amount of buffer, amount of adsorbent and effect of time on extraction were investigated and Zein BNPs were characterized by TEM, SEM, and FT-IR techniques. The main advantages of Zein as a new solid-phase extractor are that this biopolymer is non-toxic, stable, widely available, biodegradable, very hydrophobic, and can be fabricated easily. Under optimal experimental conditions, the linear correlation coefficient (r 2 ) was found to be 0.9972 at the concentration range of 5.0-1000ngmL -1 . The limit of detection was 2.3ngmL -1 (0.05μM). This method was applied successfully for the analysis of sea and river waters as well as industrial wastewater samples. Finally, this method follows the US EPA (US Environmental Protection Agency) and WHO (World Health Organization) international standards for nitrite analysis. In addition, it has several advantages to warrant its applicability in the near future in separation science as a green biosorbent in both dispersive and normal solid-phase extraction. Copyright © 2017. Published by Elsevier B.V.

Regulation of Nitrite Stress Response in Desulfovibrio vulgaris Hildenborough, a Model Sulfate-Reducing Bacterium

DOE PAGES

Rajeev, Lara; Chen, Amy; Kazakov, Alexey E.; ...

2015-08-17

Sulfate-reducing bacteria (SRB) are sensitive to low concentrations of nitrite, and nitrite has been used to control SRB-related biofouling in oil fields. Desulfovibrio vulgaris Hildenborough, a model SRB, carries a cytochrome c-type nitrite reductase (nrfHA) that confers resistance to low concentrations of nitrite. The regulation of this nitrite reductase has not been directly examined to date. In this study, we show that DVU0621 (NrfR), a sigma54-dependent two-component system response regulator, is the positive regulator for this operon. NrfR activates the expression of the nrfHA operon in response to nitrite stress. We also show that nrfR is needed for fitness atmore » low cell densities in the presence of nitrite because inactivation of nrfR affects the rate of nitrite reduction. We also predict and validate the binding sites for NrfR upstream of the nrfHA operon using purified NrfR in gel shift assays. Here we discuss possible roles for NrfR in regulating nitrate reductase genes in nitrate-utilizing Desulfovibrio spp. The NrfA nitrite reductase is prevalent across several bacterial phyla and required for dissimilatory nitrite reduction. However, regulation of the nrfA gene has been studied in only a few nitrate-utilizing bacteria. Here, we show that in D. vulgaris, a bacterium that does not respire nitrate, the expression of nrfHA is induced by NrfR upon nitrite stress. This is the first report of regulation of nrfA by a sigma54-dependent two-component system. Finally, our study increases our knowledge of nitrite stress responses and possibly of the regulation of nitrate reduction in SRB.« less

Blood Pressure-Lowering Effect of Orally Ingested Nitrite Is Abolished by a Proton Pump Inhibitor.

PubMed

Montenegro, Marcelo F; Sundqvist, Michaela L; Larsen, Filip J; Zhuge, Zhengbing; Carlström, Mattias; Weitzberg, Eddie; Lundberg, Jon O

2017-01-01

Inorganic nitrate and nitrite from dietary and endogenous sources are metabolized to NO and other bioactive nitrogen oxides that affect blood pressure. The mechanisms for nitrite bioactivation are unclear, but recent studies in rodents suggest that gastric acidity may influence the systemic effects of this anion. In a randomized, double-blind, placebo-controlled crossover study, we tested the effects of a proton pump inhibitor on the acute cardiovascular effects of nitrite. Fifteen healthy nonsmoking, normotensive subjects, aged 19 to 39 years, were pretreated with placebo or esomeprazole (3×40 mg) before ingesting sodium nitrite (0.3 mg kg -1 ), followed by blood pressure monitoring. Nitrite reduced systolic blood pressure by a maximum of 6±1.3 mm Hg when taken after placebo, whereas pretreatment with esomeprazole blunted this effect. Peak plasma nitrite, nitrate, and nitroso species levels after nitrite ingestion were similar in both interventions. In 8 healthy volunteers, we then infused increasing doses of sodium nitrite (1, 10, and 30 nmol kg -1 min -1 ) intravenously. Interestingly, although plasma nitrite peaked at similar levels as with orally ingested nitrite (≈1.8 µmol/L), no changes in blood pressure were observed. In rodents, esomeprazole did not affect the blood pressure response to the NO donor, DEA NONOate, or vascular relaxation to nitroprusside and acetylcholine, demonstrating an intact downstream NO-signaling pathway. We conclude that the acute blood pressure-lowering effect of nitrite requires an acidic gastric environment. Future studies will reveal if the cardiovascular complications associated with the use of proton pump inhibitors are linked to interference with the nitrate-nitrite-NO pathway. © 2016 American Heart Association, Inc.

Secondary targets of nitrite-derived reactive nitrogen species: nitrosation/nitration pathways, antioxidant defense mechanisms and toxicological implications.

PubMed

d'Ischia, Marco; Napolitano, Alessandra; Manini, Paola; Panzella, Lucia

2011-12-19

Nitrite, the primary metabolite of nitric oxide (NO) and a widely diffused component of human diet, plays distinct and increasingly appreciated roles in human physiology. However, when exposed to acidic environments, typically in the stomach, or under oxidative stress conditions, it may be converted to a range of reactive nitrogen species (RNS) which in turn can target a variety of biomolecules. Typical consequences of toxicological relevance include protein modification, DNA base deamination and the formation of N-nitrosamines, among the most potent mutagenic and carcinogenic compounds for humans. Besides primary biomolecules, nitrite can cause structural modifications to a variety of endogenous and exogenous organic compounds, ranging from polyunsaturated fatty acids to estrogens, tocopherol, catecholamines, furans, retinoids, dietary phenols, and a range of xenobiotics. The study of the interactions between nitrite and key food components, including phenolic antioxidants, has therefore emerged as an area of great promise for delineating innovative strategies in cancer chemoprevention. Depending on substrates and conditions, diverse reaction pathways may compete to determine product features and distribution patterns. These include nitrosation and nitration but also oxidation, via electron transfer to nitrosonium ion or nitrogen dioxide. This contribution aims to provide an overview of the main classes of compounds that can be targeted by nitrite and to discuss at chemical levels the possible reaction mechanisms under conditions that model those occurring in the stomach. The toxicological implications of the nitrite-modified molecules are finally addressed, and a rational chemical approach to the design of potent antinitrosing agents is illustrated. © 2011 American Chemical Society

An Evaluation of Alternatives to Nitrites and Sulfites to Inhibit the Growth of Salmonella enterica and Listeria monocytogenes in Meat Products

PubMed Central

Lamas, Alexandre; Miranda, José Manuel; Vázquez, Beatriz; Cepeda, Alberto; Franco, Carlos Manuel

2016-01-01

In recent years, the use of nitrites and sulfites as food preservatives has been a cause for concern due to the health problems that these additives can cause in humans. Natural products have been studied as an alternative, but most of them have hardly been applied in the food industry for technological and economic reasons. In this sense, organic salts such as sodium acetate are a good alternative due to their affordability. Thus, this study evaluated the capacity of sodium nitrite, sodium sulfite, a sodium acetate product (TQI C-6000), and chitosan to inhibit two important foodborne pathogens, Salmonella enterica and Listeria monocytogenes. The MIC of each chemical was in vitro evaluated and their antibacterial action was subsequently checked in situ using minced meat as a food model. MIC values of sodium nitrite (10,000 mg/L) and sodium sulfite (50,000 mg/L) for Salmonella enterica were higher than the values allowed by legislation (450 mg/L for sulfites and 150 mg/L for nitrites). Additionally, the sodium acetate product caused the inhibition of Salmonella enterica and Listeria at a relative low quantity. The two foodborne pathogens were inhibited in the food model with 1% of the sodium acetate product. Additionally, there were no significant differences between sodium nitrite, sodium sulfite, and sodium acetate products in the inhibition of Salmonella enterica and Listeria monocytogenes in the food model. Thus, products based on sodium acetate can be an alternative to traditional preservatives in food products. PMID:28231169

An Evaluation of Alternatives to Nitrites and Sulfites to Inhibit the Growth of Salmonella enterica and Listeria monocytogenes in Meat Products.

PubMed

Lamas, Alexandre; Miranda, José Manuel; Vázquez, Beatriz; Cepeda, Alberto; Franco, Carlos Manuel

2016-10-31

In recent years, the use of nitrites and sulfites as food preservatives has been a cause for concern due to the health problems that these additives can cause in humans. Natural products have been studied as an alternative, but most of them have hardly been applied in the food industry for technological and economic reasons. In this sense, organic salts such as sodium acetate are a good alternative due to their affordability. Thus, this study evaluated the capacity of sodium nitrite, sodium sulfite, a sodium acetate product (TQI C-6000), and chitosan to inhibit two important foodborne pathogens, Salmonella enterica and Listeria monocytogenes . The MIC of each chemical was in vitro evaluated and their antibacterial action was subsequently checked in situ using minced meat as a food model. MIC values of sodium nitrite (10,000 mg/L) and sodium sulfite (50,000 mg/L) for Salmonella enterica were higher than the values allowed by legislation (450 mg/L for sulfites and 150 mg/L for nitrites). Additionally, the sodium acetate product caused the inhibition of Salmonella enterica and Listeria at a relative low quantity. The two foodborne pathogens were inhibited in the food model with 1% of the sodium acetate product. Additionally, there were no significant differences between sodium nitrite, sodium sulfite, and sodium acetate products in the inhibition of Salmonella enterica and Listeria monocytogenes in the food model. Thus, products based on sodium acetate can be an alternative to traditional preservatives in food products.

Detection and diversity of fungal nitric oxide reductase genes ( p450nor) in agricultural soils

DOE PAGES

Higgins, Steven A.; Welsh, Allana; Orellana, Luis H.; ...

2016-03-11

Members of the Fungi convert nitrate (NO 3 -) and nitrite (NO 2 -) to gaseous nitrous oxide (N 2O) (denitrification), but the fungal contributions to N-loss from soil remain uncertain. Cultivation-based methodologies that include antibiotics to selectively assess fungal activities have limitations and complementary molecular approaches to assign denitrification potential to fungi are desirable. Microcosms established with soils from two representative U.S. Midwest agricultural regions produced N 2O from added NO 3 - or NO 2 - in the presence of antibiotics to inhibit bacteria. Cultivation efforts yielded 214 fungal isolates belonging to at least 15 distinct morphological groups,more » of which 151 produced N 2O from NO 2 -. Novel PCR primers targeting the p450nor gene that encodes the nitric oxide (NO) reductase responsible for N 2O production in fungi yielded 26 novel p450nor amplicons from DNA of 37 isolates and 23 amplicons from environmental DNA obtained from two agricultural soils. The sequences shared 54-98% amino acid identity to reference P450nor sequences within the phylum Ascomycota, and expand the known fungal P450nor sequence diversity. p450nor was detected in all fungal isolates that produced N 2O from nitrite, whereas nirK (encoding the NO-forming nitrite reductase) was amplified in only 13-74% of the N 2O-forming isolates using two separate nirK primer sets. Altogether, our findings demonstrate the value of p450nor-targeted PCR to complement existing approaches to assess the fungal contributions to denitrification and N 2O formation.« less

Quality-assurance data for routine water analysis in the National Water-Quality Laboratory of the US Geological Survey for water year 1988

USGS Publications Warehouse

Lucey, K.J.

1989-01-01

The US Geological Survey maintains a quality assurance program based on the analysis of reference samples for its National Water Quality Laboratory located in Denver, Colorado. Reference samples containing selected inorganic, nutrient, and precipitation (low-level concentration) constituents are prepared at the Survey 's Water Quality Services Unit in Ocala, Florida, disguised as routine samples, and sent daily or weekly, as appropriate, to the laboratory through other Survey offices. The results are stored permanently in the National Water Data Storage and Retrieval System (WATSTORE), the Survey 's database for all water data. These data are analyzed statistically for precision and bias. An overall evaluation of the inorganic major ion and trace metal constituent data for water year 1988 indicated a lack of precision in the National Water Quality Laboratory for the determination of 8 out of 58 constituents: calcium (inductively coupled plasma emission spectrometry), fluoride, iron (atomic absorption spectrometry), iron (total recoverable), magnesium (atomic absorption spectrometry), manganese (total recoverable), potassium, and sodium (inductively coupled plasma emission spectrometry). The results for 31 constituents had positive or negative bias during water year 1988. A lack of precision was indicated in the determination of three of the six nutrient constituents: nitrate plus nitrite nitrogen as nitrogen, nitrite nitrogen as nitrogen, and orthophosphate as phosphorus. A biased condition was indicated in the determination of ammonia nitrogen as nitrogen, ammonia plus organic nitrogen as nitrogen, and nitrate plus nitrite nitrogen as nitrogen. There was acceptable precision in the determination of all 10 constituents contained in precipitation samples. Results for ammonia nitrogen as nitrogen, sodium, and fluoride indicated a biased condition. (Author 's abstract)

Detection and diversity of fungal nitric oxide reductase genes ( p450nor) in agricultural soils

DOE Office of Scientific and Technical Information (OSTI.GOV)

Higgins, Steven A.; Welsh, Allana; Orellana, Luis H.

Members of the Fungi convert nitrate (NO 3 -) and nitrite (NO 2 -) to gaseous nitrous oxide (N 2O) (denitrification), but the fungal contributions to N-loss from soil remain uncertain. Cultivation-based methodologies that include antibiotics to selectively assess fungal activities have limitations and complementary molecular approaches to assign denitrification potential to fungi are desirable. Microcosms established with soils from two representative U.S. Midwest agricultural regions produced N 2O from added NO 3 - or NO 2 - in the presence of antibiotics to inhibit bacteria. Cultivation efforts yielded 214 fungal isolates belonging to at least 15 distinct morphological groups,more » of which 151 produced N 2O from NO 2 -. Novel PCR primers targeting the p450nor gene that encodes the nitric oxide (NO) reductase responsible for N 2O production in fungi yielded 26 novel p450nor amplicons from DNA of 37 isolates and 23 amplicons from environmental DNA obtained from two agricultural soils. The sequences shared 54-98% amino acid identity to reference P450nor sequences within the phylum Ascomycota, and expand the known fungal P450nor sequence diversity. p450nor was detected in all fungal isolates that produced N 2O from nitrite, whereas nirK (encoding the NO-forming nitrite reductase) was amplified in only 13-74% of the N 2O-forming isolates using two separate nirK primer sets. Altogether, our findings demonstrate the value of p450nor-targeted PCR to complement existing approaches to assess the fungal contributions to denitrification and N 2O formation.« less

Arabidopsis Root-Type Ferredoxin:NADP(H) Oxidoreductase 2 is Involved in Detoxification of Nitrite in Roots.

PubMed

Hachiya, Takushi; Ueda, Nanae; Kitagawa, Munenori; Hanke, Guy; Suzuki, Akira; Hase, Toshiharu; Sakakibara, Hitoshi

2016-11-01

Ferredoxin:NADP(H) oxidoreductase (FNR) plays a key role in redox metabolism in plastids. Whereas leaf FNR (LFNR) is required for photosynthesis, root FNR (RFNR) is believed to provide electrons to ferredoxin (Fd)-dependent enzymes, including nitrite reductase (NiR) and Fd-glutamine-oxoglutarate aminotransferase (Fd-GOGAT) in non-photosynthetic conditions. In some herbal species, however, most nitrate reductase activity is located in photosynthetic organs, and ammonium in roots is assimilated mainly by Fd-independent NADH-GOGAT. Therefore, RFNR might have a limited impact on N assimilation in roots grown with nitrate or ammonium nitrogen sources. AtRFNR genes are rapidly induced by application of toxic nitrite. Thus, we tested the hypothesis that RFNR could contribute to nitrite reduction in roots by comparing Arabidopsis thaliana seedlings of the wild type with loss-of-function mutants of RFNR2 When these seedlings were grown under nitrate, nitrite or ammonium, only nitrite nutrition caused impaired growth and nitrite accumulation in roots of rfnr2 Supplementation of nitrite with nitrate or ammonium as N sources did not restore the root growth in rfnr2 Also, a scavenger for nitric oxide (NO) could not effectively rescue the growth impairment. Thus, nitrite toxicity, rather than N depletion or nitrite-dependent NO production, probably causes the rfnr2 root growth defect. Our results strongly suggest that RFNR2 has a major role in reduction of toxic nitrite in roots. A specific set of genes related to nitrite reduction and the supply of reducing power responded to nitrite concomitantly, suggesting that the products of these genes act co-operatively with RFNR2 to reduce nitrite in roots. © The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Effects of nitrite exposure on functional haemoglobin levels, bimodal respiration, and swimming performance in the facultative air-breathing fish Pangasianodon hypophthalmus.

PubMed

Lefevre, Sjannie; Jensen, Frank B; Huong, Do T T; Wang, Tobias; Phuong, Nguyen T; Bayley, Mark

2011-07-01

In this study we investigated nitrite (NO₂⁻) effects in striped catfish, a facultative air-breather. Fish were exposed to 0, 0.4, and 0.9 mM nitrite for 0, 1, 2, 4, and 7 days, and levels of functional haemoglobin, methaemoglobin (metHb) and nitrosyl haemoglobin (HbNO) were assessed using spectral deconvolution. Plasma concentrations of nitrite, nitrate, chloride, potassium, and sodium were also measured. Partitioning of oxygen consumption was determined to reveal whether elevated metHb (causing functional hypoxia) induced air-breathing. The effects of nitrite on maximum oxygen uptake (MO(2max)) and critical swimming speed (U(crit)) were also assessed. Striped catfish was highly tolerant to nitrite exposure, as reflected by a 96 h LC₅₀ of 1.65 mM and a moderate nitrite uptake into the blood. Plasma levels of nitrite reached a maximum after 1 day of exposure, and then decreased, never exceeding ambient levels. MetHb, HbNO and nitrate (a nitrite detoxification product) also peaked after 1 day and then decreased. Only high levels of nitrite and metHb caused reductions in MO(2max) and U(crit). The response of striped catfish contrasts with that seen in most other fish species and discloses efficient mechanisms of combating nitrite threats. Furthermore, even though striped catfish is an efficient air-breather, this species has the ability to sustain aerobic scope and swimming performance without air-breathing, even when faced with nitrite-induced reductions in blood oxygen carrying capacity. Our study is the first to confirm that high levels of nitrite and metHb reduce MO(2max) and thereby aerobic scope, while more moderate elevations fail to do so. Further studies are needed to elucidate the mechanisms underlying the low nitrite accumulation in striped catfish. Copyright © 2011 Elsevier B.V. All rights reserved.

The use and control of nitrate and nitrite for the processing of meat products.

PubMed

Honikel, Karl-Otto

2008-01-01

Nitrate and nitrite are used for the purpose of curing meat products. In most countries the use of both substances, usually added as potassium or sodium salts, is limited. Either the ingoing or the residual amounts are regulated by laws. The effective substance is nitrite acting primarily as an inhibitor for some microorganisms. Nitrite added to a batter of meat is partially oxidized to nitrate by sequestering oxygen - thus it acts as an antioxidant - a part of nitrite is bound to myoglobin, forming the heat stable NO-myoglobin, a part is bound to proteins or other substances in meat. Nitrate may be reduced to nitrite in raw meat products by microorganisms. As oxidation and reduction may occur the concentrations of nitrite plus nitrate in a product has to be controlled and measured especially if the residual amounts are regulated. This sum of both compounds is important for the human body. Intake of nitrate with food leads to its absorption over the digestive tract into the blood. In the oral cavity nitrate appears again where it is reduced to nitrite. With the saliva the nitrite is mixed with food, having the same effect as nitrite in a batter (inhibiting growth of some pathogenic microorganisms) and swallowed. In the stomach nitrite can eventually form carcinogenic nitrosamines in the acidic environment.

Influence of turkey meat on residual nitrite in cured meat products.

PubMed

Kilic, B; Cassens, R G; Borchert, L L

2001-02-01

A response surface experimental design was employed to estimate residual nitrite level at various initial nitrite concentrations, percent turkey meat in the formula, and heat quantity (F) values using a typical wiener as the test system. Pork and mechanically separated turkey were used as the meat ingredients. Residual nitrite and pH were measured at day 1, 7 days, 14 days, and 49 days after processing. Protein, fat, salt, moisture, and CIE (L*a*b*) color values were also determined. Results showed that the effect of turkey meat on residual nitrite level was significant (P < 0.01). An increased amount of turkey meat in the formula resulted in lower residual nitrite levels at a fixed pH. The residual nitrite level was initially proportional to initial nitrite concentration, but it became a nonsignificant factor during longer storage time. Differences in heat quantity had a significant effect (P < 0.05) on residual nitrite level initially. Greater heat quantity decreased residual nitrite level in finished cured meat products at a fixed pH. However, this effect became nonsignificant during longer storage. Reduction of residual nitrite in wieners because of turkey meat addition at a fixed pH was due to characteristics of the turkey tissue, but the mechanism of action remains unknown. It was also established that commercial wieners had a higher pH if poultry meat was included in the formulation.

Comparison of Oxidation Kinetics of Nitrite-Oxidizing Bacteria: Nitrite Availability as a Key Factor in Niche Differentiation

PubMed Central

Nowka, Boris; Daims, Holger

2014-01-01

Nitrification has an immense impact on nitrogen cycling in natural ecosystems and in wastewater treatment plants. Mathematical models function as tools to capture the complexity of these biological systems, but kinetic parameters especially of nitrite-oxidizing bacteria (NOB) are lacking because of a limited number of pure cultures until recently. In this study, we compared the nitrite oxidation kinetics of six pure cultures and one enrichment culture representing three genera of NOB (Nitrobacter, Nitrospira, Nitrotoga). With half-saturation constants (Km) between 9 and 27 μM nitrite, Nitrospira bacteria are adapted to live under significant substrate limitation. Nitrobacter showed a wide range of lower substrate affinities, with Km values between 49 and 544 μM nitrite. However, the advantage of Nitrobacter emerged under excess nitrite supply, sustaining high maximum specific activities (Vmax) of 64 to 164 μmol nitrite/mg protein/h, contrary to the lower activities of Nitrospira of 18 to 48 μmol nitrite/mg protein/h. The Vmax (26 μmol nitrite/mg protein/h) and Km (58 μM nitrite) of “Candidatus Nitrotoga arctica” measured at a low temperature of 17°C suggest that Nitrotoga can advantageously compete with other NOB, especially in cold habitats. The kinetic parameters determined represent improved basis values for nitrifying models and will support predictions of community structure and nitrification rates in natural and engineered ecosystems. PMID:25398863

Reaction of cytochrome c with nitrite and nitric oxide. A model of dissimilatory nitrite reductase.

PubMed

Orii, Y; Shimada, H

1978-12-01

The reaction of bovine heart ferrocytochrome c with nitrite was studied under various conditions. The reaction product was ferricytochrome c at around pH 5, whereas at around pH 3 it was Compound I, characterized by twin peaks at 529 and 563 nm of equal intensity. However, ferrocytochrome c decreased obeying first-order kinetics over the pH range examined, irrespective of the presence or absence of molecular oxygen. The apparent first-order rate constant was proportional to the square of the nitrite concentration at pH 4.4 and it increased as the pH was lowered. At pH 3 the reaction was so rapid that it had to be followed by stopped-flow and rapid-scanning techniques. The apparent rate constant at this pH was found to increase linearly with the nitrite concentration. Based on these results the active species of nitrite was concluded to be dinitrogen trioxide at pH 4.4 and nitrosonium ion, no+, at pH 3. Compound II was formed by reaction of ferrocytochrome c and NO gas at acidic and alkaline pH values. The absorption peaks were at 533 and 563 nm at pH 3, and at 538 and 567 nm at pH 12.9. This compound was also formed by reducing Compound I with reductants. Compound I prepared from ferricytochrome c and NO was stable below pH 6. However, appreciable absorption peaks for ferrocytochrome c appeared between pH 8 and 10, because Compound I was dissociated into ferrocytochrome c and NO+, and because ferrocytochrome c thus formed reacted with NO very slowly in this pH region. Saccharomyces ferricytochrome c under NO gas behaved differently from mammalian cytochrome, indicating the significance of the nature of the heme environment in determing the reactivity. Only at extreme pH values was Compound II formed exclusively and persisted. A model system for dissimilatory nitrite reductase was constructed by using bovine heart cytochrome c, nitrite and NADH plus PMS at pH 3.3, and a scheme involving cyclic turnover of ferrocytochrome c, Compound I and Compound II is presented, with kinetic parameters.

Optimization of free ammonia concentration for nitrite accumulation in shortcut biological nitrogen removal process.

PubMed

Chung, Jinwook; Shim, Hojae; Park, Seong-Jun; Kim, Seung-Jin; Bae, Wookeun

2006-03-01

A shortcut biological nitrogen removal (SBNR) utilizes the concept of a direct conversion of ammonium to nitrite and then to nitrogen gas. A successful SBNR requires accumulation of nitrite in the system and inhibition of the activity of nitrite oxidizers. A high concentration of free ammonia (FA) inhibits nitrite oxidizers, but unfortunately decreases the ammonium removal rate as well. Therefore, the optimal range of FA concentration is necessary not only to stabilize nitrite accumulation but also to achieve maximum ammonium removal. In order to derive such optimal FA concentrations, the specific substrate utilization rates of ammonium and nitrite oxidizers were measured. The optimal FA concentration range appeared to be 5-10 mg/L for the adapted sludge. The simulated results from the modified inhibition model expressed by FA and ammonium/nitrite concentrations were shown very similar to the experimental results.

Bioelectrode-based approach for enhancing nitrate and nitrite removal and electricity generation from eutrophic lakes.

PubMed

Zhang, Yifeng; Angelidaki, Irini

2012-12-01

Nitrate and nitrite contamination of surface waters (e.g. lakes) has become a severe environmental and health problem, especially in developing countries. The recent demonstration of nitrate reduction at the cathode of microbial fuel cell (MFC) provides an opportunity to develop a new technology for nitrogen removal from surface waters. In this study, a sediment-type MFC based on two pieces of bioelectrodes was employed as a novel in situ applicable approach for nitrogen removal, as well as electricity production from eutrophic lakes. Maximum power density of 42 and 36 mW/m(2) was produced respectively from nitrate- and nitrite-rich synthetic lake waters at initial concentration of 10 mg-N/L. Along with the electricity production a total nitrogen removal of 62% and 77% was accomplished, for nitrate and nitrite, respectively. The nitrogen removal was almost 4 times higher under close-circuit condition with biocathode, compared to either the open-circuit operation or with abiotic cathode. The mass balance on nitrogen indicates that most of the removed nitrate and nitrite (84.7 ± 0.1% and 81.8 ± 0.1%, respectively) was reduced to nitrogen gas. The nitrogen removal and power generation was limited by the dissolved oxygen (DO) level in the water and acetate level injected to the sediment. Excessive oxygen resulted in dramatically decrease of nitrogen removal efficiency and only 7.8% removal was obtained at DO level of 7.8 mg/l. The power generation and nitrogen removal increased with acetate level and was nearly saturated at 0.84 mg/g-sediment. This bioelectrode-based in situ approach is attractive not only due to the electricity production, but also due to no need of extra reactor construction, which may broaden the application possibilities of sediment MFC technology. Copyright © 2012 Elsevier Ltd. All rights reserved.

Nitrite and Nitrate Concentrations and Metabolism in Breast Milk, Infant Formula, and Parenteral Nutrition

PubMed Central

Jones, Jesica A.; Ninnis, Janet R.; Hopper, Andrew O.; Ibrahim, Yomna; Merritt, T. Allen; Wan, Kim-Wah; Power, Gordon G.; Blood, Arlin B.

2015-01-01

Dietary nitrate and nitrite are sources of gastric NO, which modulates blood flow, mucus production, and microbial flora. However, the intake and importance of these anions in infants is largely unknown. Nitrate and nitrite levels were measured in breast milk of mothers of preterm and term infants, infant formulas, and parenteral nutrition. Nitrite metabolism in breast milk was measured after freeze-thawing, at different temperatures, varying oxygen tensions, and after inhibition of potential nitrite-metabolizing enzymes. Nitrite concentrations averaged 0.07 ± 0.01 μM in milk of mothers of preterm infants, less than that of term infants (0.13 ± 0.02 μM) (P < .01). Nitrate concentrations averaged 13.6 ± 3.7 μM and 12.7 ± 4.9 μM, respectively. Nitrite and nitrate concentrations in infant formulas varied from undetectable to many-fold more than breast milk. Concentrations in parenteral nutrition were equivalent to or lower than those of breast milk. Freeze-thawing decreased nitrite concentration ∼64%, falling with a half-life of 32 minutes at 37°C. The disappearance of nitrite was oxygen-dependent and prevented by ferricyanide and 3 inhibitors of lactoperoxidase. Nitrite concentrations in breast milk decrease with storage and freeze-thawing, a decline likely mediated by lactoperoxidase. Compared to adults, infants ingest relatively little nitrite and nitrate, which may be of importance in the modulation of blood flow and the bacterial flora of the infant GI tract, especially given the protective effects of swallowed nitrite. PMID:23894175

Nitrite and nitrate concentrations and metabolism in breast milk, infant formula, and parenteral nutrition.

PubMed

Jones, Jesica A; Ninnis, Janet R; Hopper, Andrew O; Ibrahim, Yomna; Merritt, T Allen; Wan, Kim-Wah; Power, Gordon G; Blood, Arlin B

2014-09-01

Dietary nitrate and nitrite are sources of gastric NO, which modulates blood flow, mucus production, and microbial flora. However, the intake and importance of these anions in infants is largely unknown. Nitrate and nitrite levels were measured in breast milk of mothers of preterm and term infants, infant formulas, and parenteral nutrition. Nitrite metabolism in breast milk was measured after freeze-thawing, at different temperatures, varying oxygen tensions, and after inhibition of potential nitrite-metabolizing enzymes. Nitrite concentrations averaged 0.07 ± 0.01 μM in milk of mothers of preterm infants, less than that of term infants (0.13 ± 0.02 μM) (P < .01). Nitrate concentrations averaged 13.6 ± 3.7 μM and 12.7 ± 4.9 μM, respectively. Nitrite and nitrate concentrations in infant formulas varied from undetectable to many-fold more than breast milk. Concentrations in parenteral nutrition were equivalent to or lower than those of breast milk. Freeze-thawing decreased nitrite concentration ~64%, falling with a half-life of 32 minutes at 37°C. The disappearance of nitrite was oxygen-dependent and prevented by ferricyanide and 3 inhibitors of lactoperoxidase. Nitrite concentrations in breast milk decrease with storage and freeze-thawing, a decline likely mediated by lactoperoxidase. Compared to adults, infants ingest relatively little nitrite and nitrate, which may be of importance in the modulation of blood flow and the bacterial flora of the infant GI tract, especially given the protective effects of swallowed nitrite. © 2013 American Society for Parenteral and Enteral Nutrition.

Inhaled nitrite reverses hemolysis-induced pulmonary vasoconstriction in newborn lambs without blood participation

PubMed Central

Blood, Arlin B.; Schroeder, Hobe J.; Terry, Michael H.; Merrill-Henry, Jeanette; Bragg, Shannon L.; Vrancken, Kurt; Liu, Taiming; Herring, Jason L.; Sowers, Lawrence C.; Wilson, Sean M.; Power, Gordon G.

2011-01-01

Background Nitrite can be converted to nitric oxide (NO) by a number of different biochemical pathways. In newborn lambs an aerosol of inhaled nitrite has been found to reduce pulmonary blood pressure, possibly acting via conversion to NO by reaction with intraerythrocytic deoxyhemoglobin. If so, the vasodilating effects of nitrite would be attenuated by free hemoglobin in plasma that would rapidly scavenge NO. Methods and Results Pulmonary vascular pressures and resistances to flow were measured in anesthetized newborn lambs. Plasma hemoglobin concentrations were then elevated, resulting in marked pulmonary hypertension. This effect was attenuated if infused hemoglobin was first oxidized to methemoglobin which does not scavenge NO. These results further implicate NO as a tonic pulmonary vasodilator. Next, while free hemoglobin continued to be infused, the lambs were given inhaled NO gas (20 ppm), inhaled sodium nitrite aerosol (0.87 M), or an intravascular nitrite infusion (3 mg·hr−1 bolus, 5 mg·kg−1·hr−1 infusion). Inhaled NO and inhaled nitrite aerosol both resulted in pulmonary vasodilation. Intravascular infusion of nitrite, however, did not. Increases in exhaled NO gas were observed while breathing the nitrite aerosol (~20 ppb NO) but not during intravascular infusion of nitrite. Conclusions We conclude that the pulmonary vasodilating effect of inhaled nitrite results from its conversion to NO in airway and parenchymal lung tissue and is not dependent on reactions with deoxyhemoglobin in the pulmonary circulation. Inhaled nitrite aerosol remains a promising candidate to reduce pulmonary hypertension in clinical application. PMID:21282501

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rajeev, Lara; Chen, Amy; Kazakov, Alexey E.

Sulfate-reducing bacteria (SRB) are sensitive to low concentrations of nitrite, and nitrite has been used to control SRB-related biofouling in oil fields. Desulfovibrio vulgaris Hildenborough, a model SRB, carries a cytochrome c-type nitrite reductase (nrfHA) that confers resistance to low concentrations of nitrite. The regulation of this nitrite reductase has not been directly examined to date. In this study, we show that DVU0621 (NrfR), a sigma54-dependent two-component system response regulator, is the positive regulator for this operon. NrfR activates the expression of the nrfHA operon in response to nitrite stress. We also show that nrfR is needed for fitness atmore » low cell densities in the presence of nitrite because inactivation of nrfR affects the rate of nitrite reduction. We also predict and validate the binding sites for NrfR upstream of the nrfHA operon using purified NrfR in gel shift assays. Here we discuss possible roles for NrfR in regulating nitrate reductase genes in nitrate-utilizing Desulfovibrio spp. The NrfA nitrite reductase is prevalent across several bacterial phyla and required for dissimilatory nitrite reduction. However, regulation of the nrfA gene has been studied in only a few nitrate-utilizing bacteria. Here, we show that in D. vulgaris, a bacterium that does not respire nitrate, the expression of nrfHA is induced by NrfR upon nitrite stress. This is the first report of regulation of nrfA by a sigma54-dependent two-component system. Finally, our study increases our knowledge of nitrite stress responses and possibly of the regulation of nitrate reduction in SRB.« less

Nitrogen Removal over Nitrite by Aeration Control in Aerobic Granular Sludge Sequencing Batch Reactors

PubMed Central

Lochmatter, Samuel; Maillard, Julien; Holliger, Christof

2014-01-01

This study investigated the potential of aeration control for the achievement of N-removal over nitrite with aerobic granular sludge in sequencing batch reactors. N-removal over nitrite requires less COD, which is particularly interesting if COD is the limiting parameter for nutrient removal. The nutrient removal performances for COD, N and P have been analyzed as well as the concentration of nitrite-oxidizing bacteria in the granular sludge. Aeration phase length control combined with intermittent aeration or alternate high-low DO, has proven to be an efficient way to reduce the nitrite-oxidizing bacteria population and hence achieve N-removal over nitrite. N-removal efficiencies of up to 95% were achieved for an influent wastewater with COD:N:P ratios of 20:2.5:1. The total N-removal rate was 0.18 kgN·m−3·d−1. With N-removal over nitrate the N-removal was only 74%. At 20 °C, the nitrite-oxidizing bacteria concentration decreased by over 95% in 60 days and it was possible to switch from N-removal over nitrite to N-removal over nitrate and back again. At 15 °C, the nitrite-oxidizing bacteria concentration decreased too but less, and nitrite oxidation could not be completely suppressed. However, the combination of aeration phase length control and high-low DO was also at 15 °C successful to maintain the nitrite pathway despite the fact that the maximum growth rate of nitrite-oxidizing bacteria at temperatures below 20 °C is in general higher than the one of ammonium-oxidizing bacteria. PMID:25006970

Interactions between ammonia and nitrite oxidizing bacteria in co-cultures: Is there evidence for mutualism, commensalism, or competition?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sayavedra-Soto, Luis; Arp, Daniel

Nitrification is a two-step environmental microbial process in the nitrogen cycle in which ammonia is oxidized to nitrate. Ammonia-oxidizing bacteria and archaea oxidize ammonia to nitrite and nitrite is oxidized to nitrate by nitrite-oxidizing bacteria. These microorganisms, which likely act in concert in a microbial community, play critical roles in the movement of inorganic N in soils, sediments and waters and are essential to the balance of the nitrogen cycle. Anthropogenic activity has altered the balance of the nitrogen cycle through agriculture practices and organic waste byproducts. Through their influence on available N for plant growth, nitrifying microorganisms influence plantmore » productivity for food and fiber production and the associated carbon sequestration. N Fertilizer production, primarily as ammonia, requires large inputs of natural gas and hydrogen. In croplands fertilized with ammonia-based fertilizers, nitrifiers contribute to the mobilization of this N by producing nitrate (NO3-), wasting the energy used in the production and application of ammonia-based fertilizer. The resulting nitrate is readily leached from these soils, oxidized to gaseous N oxides (greenhouse gases), and denitrified to N2 (which is no longer available as a plant N source). Still, ammonia oxidizers are beneficial in the treatment of wastewater and they also show potential to contribute to microbial bioremediation strategies for clean up of environments contaminated with chlorinated hydrocarbons. Mitigation of the negative effects and exploitation of the beneficial effects of nitrifiers will be facilitated by a systems-level understanding of the interactions of ammonia-oxidizing bacteria and nitrite-oxidizing bacteria with the environment and with each other.« less

Nitrites and nitrates in the human diet: Carcinogens or beneficial hypotensive agents?

PubMed

Butler, Anthony

2015-06-05

The presence of nitrite in the human diet was thought to constitute a hazard as secondary nitrosamines are known to cause gastric cancers. Recent publications on the physiology of serum nitrite have been consulted. Nitrite is added to some foodstuffs as an antibotulinum agent. The epidemiological evidence that nitrite causes gastric ulcers is weak. On the other hand, evidence that the presence of nitrite in serum lowers blood pressure is strong. This allows us to explain why a Tang dynasty treatment for angina, given in a Dunhuang medical manuscript, can be successful. The presence of nitrite in food is free of danger and a diet high in nitrate is beneficial to the health. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Determination of Nitrite in Whole Blood by High-Performance Liquid Chromatography with Electrochemical Detection and a Case of Nitrite Poisoning.

PubMed

Yan, Hui; Zhuo, Xiangyi; Shen, Baohua; Xiang, Ping; Shen, Min

2016-01-01

Although nitrite is widely used in meat processing, it is a major toxicity hazard to children and is responsible for the blue-baby syndrome. A simple and effective method to determine nitrite in whole blood has been devised using ion chromatography with suppressed conductivity detection. The blood sample was deproteinized by adding acetonitrile and purified with mini-cartridges to remove hydrophobic compounds, chloride ions, and metal ions. An aliquot of the filtrate was injected onto the ion chromatography. The retention time for nitrite was 13.8 min and the detection limit of nitrite in whole blood was 0.4 μmol/L. The calibration curve was linear (r(2) = 0.9999) over the concentration working range. The blood nitrite concentration of a victim who attempted suicide by ingesting sodium nitrite powder was determined using the present method. The basal levels for nitrite in human blood was determined with 7.1 ± 0.9 μmol/L (n = 12). © 2015 American Academy of Forensic Sciences.

Nitrate and Nitrite Reduction by Wolffia arrhiza1

PubMed Central

Swader, J. A.; Stocking, C. R.

1971-01-01

Nitrate reductase was not found to be present in or associated with partially purified, intact chloroplasts aqueously isolated from Wolffia arrhiza. Such chloroplasts are capable of using nitrite but not nitrate as an electron acceptor during light-stimulated electron transport in the absence of additional cytoplasmic components. When nitrite acts as an electron acceptor under these conditions, on the average 1.5 moles of oxygen are evolved per mole of nitrite reduced by the chloroplasts, indicating a probable reduction of nitrite to ammonia. Chloroplasts ruptured by osmotic shock fail to reduce nitrite in the absence of additional components. PMID:16657592

Nitrate and Nitrite Reduction by Wolffia arrhiza.

PubMed

Swader, J A; Stocking, C R

1971-02-01

Nitrate reductase was not found to be present in or associated with partially purified, intact chloroplasts aqueously isolated from Wolffia arrhiza. Such chloroplasts are capable of using nitrite but not nitrate as an electron acceptor during light-stimulated electron transport in the absence of additional cytoplasmic components. When nitrite acts as an electron acceptor under these conditions, on the average 1.5 moles of oxygen are evolved per mole of nitrite reduced by the chloroplasts, indicating a probable reduction of nitrite to ammonia. Chloroplasts ruptured by osmotic shock fail to reduce nitrite in the absence of additional components.

Sources and sinks for ammonia and nitrite on the early Earth and the reaction of nitrite with ammonia

NASA Technical Reports Server (NTRS)

Summers, D. P.

1999-01-01

An analysis of sources and sinks for ammonia and nitrite on the early Earth was conducted. Rates of formation and destruction, and steady state concentrations of both species were determined by steady state kinetics. The importance of the reaction of nitrite with ammonia on the feasibility of ammonia formation from nitrite was evaluated. The analysis considered conditions such as temperature, ferrous iron concentration, and pH. For sinks we considered the reduction of nitrite to ammonia, reaction between nitrite and ammonia, photochemical destruction of both species, and destruction at hydrothermal vents. Under most environmental conditions, the primary sink for nitrite is reduction to ammonia. The reaction between ammonia and nitrite is not an important sink for either nitrite or ammonia. Destruction at hydrothermal vents is important at acidic pH's and at low ferrous iron concentrations. Photochemical destruction, even in a worst case scenario, is unimportant under many conditions except possibly under acidic, low iron concentration, or low temperature conditions. The primary sink for ammonia is photochemical destruction in the atmosphere. Under acidic conditions, more of the ammonia is tied up as ammonium (reducing its vapor pressure and keeping it in solution) and hydrothermal destruction becomes more important.

Two efficient nitrite-reducing Lactobacillus strains isolated from traditional fermented pork (Nanx Wudl) as competitive starter cultures for Chinese fermented dry sausage.

PubMed

Chen, Xi; Li, Jiapeng; Zhou, Tong; Li, Jinchun; Yang, Junna; Chen, Wenhua; Xiong, Youling L

2016-11-01

Lactic acid bacteria isolated from traditional Dong pork product (Nanx Wudl) were investigated for their potential as starter cultures for Chinese fermented dry sausages. Based on preliminary screening, Lactobacillus plantarum CMRC6 and Lactobacillus sakei CMRC15, both showing excellent nitrite-reducing capacity, were used as single-strain starter cultures. For comparison, a commercial composite starter was also tested. In CMRC6 and CMRC15-inoculated sausages, lactic acid bacteria dominated the microflora and improved the microbiological safety by suppression of Enterobacteriaceae growth. Nitrite content of all inoculated sausages declined rapidly during ripening compared to non-inoculated. Texture profiles analysis showed inoculated sausages had more pronounced textural development during ripening. Sensory evaluation indicated CMRC6 and CMRC15-fermented sausages had comparable or more desirable organoleptic characteristics than sausage made with commercial starters. Therefore, CMRC6 and CMRC15 are promising candidates as multi-functional starter cultures for microbiological safety and residual nitrite control in gourmet Chinese dry sausage production. Copyright © 2016 Elsevier Ltd. All rights reserved.

A high-throughput assay format for determination of nitrate reductase and nitrite reductase enzyme activities

DOE Office of Scientific and Technical Information (OSTI.GOV)

McNally, N.; Liu, Xiang Yang; Choudary, P.V.

1997-01-01

The authors describe a microplate-based high-throughput procedure for rapid assay of the enzyme activities of nitrate reductase and nitrite reductase, using extremely small volumes of reagents. The new procedure offers the advantages of rapidity, small sample size-nanoliter volumes, low cost, and a dramatic increase in the throughput sample number that can be analyzed simultaneously. Additional advantages can be accessed by using microplate reader application software packages that permit assigning a group type to the wells, recording of the data on exportable data files and exercising the option of using the kinetic or endpoint reading modes. The assay can also bemore » used independently for detecting nitrite residues/contamination in environmental/food samples. 10 refs., 2 figs.« less

Unraveling the chemical identity of meat pigments.

PubMed

Pegg, R B; Shahidi, F

1997-10-01

This review examines the chemistry of nitrite curing of meat and meat products as it relates to the development of cured meat color and provides a detailed account of how nitrite-free processed meats could be prepared using the preformed cooked cured-meat pigment (CCMP). Thus, a chemical description of meat color, both raw and cooked, and characterization of nitrosylheme pigments follows. Based on electron paramagnetic resonance (EPR), visible and infrared spectroscopic studies, evidence has been provided to support the hypothesis that the chemical structure of the preformed CCMP is identical to that of the pigment prepared in situ after thermal processing of nitrite-cured meat and is in fact a mononitrosylheme complex. An appendix, which describes the basic principles of EPR spectroscopy used in the context of this review, is attached.

Effects of different nitrite concentrations from a vegetable source with and without high hydrostatic pressure on the recovery of Listeria monocytogenes on ready-to-eat restructured ham.

PubMed

Lavieri, Nicolas A; Sebranek, Joseph G; Cordray, Joseph C; Dickson, James S; Horsch, Ashley M; Jung, Stephanie; Manu, David K; Brehm-Stecher, Byron F; Mendonça, Aubrey F

2014-05-01

Sodium nitrite exerts an inhibitory effect on the growth of Listeria monocytogenes. The objective of this study was to investigate the effects of various nitrite concentrations from a vegetable source with and without high hydrostatic pressure (HHP) on the recovery and growth of L. monocytogenes on ready-to-eat restructured ham. A preconverted celery powder was used as the vegetable source of nitrite. Targeted concentrations of natural nitrite investigated were 0, 50, and 100 mg/kg. HHP treatments evaluated were 400 MPa for 4 min and 600 MPa for 1 or 4 min at 12 ± 2 °C (initial temperature of the pressurization fluid). Viable L. monocytogenes populations were monitored on modified Oxford medium and thin agar layer medium through 98 days of storage at 4 ± 1 °C. Populations on both media did not differ. The HHP treatment at 600 MPa for 4 min resulted in L. monocytogenes populations below the detection limit of our sampling protocols throughout the storage period regardless of the natural nitrite concentration. The combination of HHP at 400 MPa for 4 min or 600 MPa for 1 min with natural nitrite resulted in initial inhibition of viable L. monocytogenes. Ham formulations that did not contain natural nitrite allowed faster growth of L. monocytogenes than did those with nitrite, regardless of whether they were treated with HHP. The results indicate that nitrite from a vegetable source at the concentrations used in this study resulted in slower growth of this microorganism. HHP treatments enhanced the inhibitory effects of natural nitrite on L. monocytogenes growth. Thus, the combination of natural nitrite plus HHP appears to have a synergistic inhibitory effect on L. monocytogenes growth.

Nitrite-derived nitric oxide protects the rat kidney against ischemia/reperfusion injury in vivo: role for xanthine oxidoreductase.

PubMed

Tripatara, Pinpat; Patel, Nimesh S A; Webb, Andrew; Rathod, Krishnaraj; Lecomte, Florence M J; Mazzon, Emanuela; Cuzzocrea, Salvatore; Yaqoob, Mohammed M; Ahluwalia, Amrita; Thiemermann, Christoph

2007-02-01

In normal conditions, nitric oxide (NO) is oxidized to the anion nitrite, but in hypoxia, this nitrite may be reduced back to NO by the nitrite reductase action of deoxygenated hemoglobin, acidic disproportionation, or xanthine oxidoreductase (XOR). Herein, is investigated the effects of topical sodium nitrite administration in a rat model of renal ischemia/reperfusion (I/R) injury. Rats were subjected to 60 min of bilateral renal ischemia and 6 h of reperfusion in the absence or presence of sodium nitrite (30 nmol) administered topically 1 min before reperfusion. Serum creatinine, serum aspartate aminotransferase, creatinine clearance, fractional excretion of Na(+), and plasma nitrite/nitrate concentrations were measured. The nitrite-derived NO-generating capacity of renal tissue was determined under acidic and hypoxic conditions by ozone chemiluminescence in homogenates of kidneys that were subjected to sham, ischemia-only, and I/R conditions. Nitrite significantly attenuated renal dysfunction and injury, an effect that was abolished by previous treatment of rats with the NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazole-1-oxyl-3-oxide (2.5 mumol intravenously 5 min before ischemia and 50 nmol topically 6 min before reperfusion). Renal tissue homogenates produced significant amounts of NO from nitrite, an effect that was attenuated significantly by the xanthine oxidoreductase inhibitor allopurinol. Taken together, these findings demonstrate that topically administered sodium nitrite protects the rat kidney against I/R injury and dysfunction in vivo via the generation, in part, of xanthine oxidoreductase-catalyzed NO production. These observations suggest that nitrite therapy might prove beneficial in protecting kidney function and integrity during periods of I/R such as those encountered in renal transplantation.

Survey of nitrite content in foods from north-east China.

PubMed

Yuan, Y; Zhang, T; Zhuang, H; Wang, K; Zheng, Y; Zhang, H; Zhou, B; Liu, J

2010-01-01

This study reports a survey of nitrite in a variety of foods consumed in north-east China and estimates the intake of nitrite for the north-east Chinese consumer. A total of 642 food categories including rice and rice products, flour and flour products, soybean and products, vegetables, fruit, preserved vegetables, cured meat products, dairy products, fish products, salt, and soy sauce were analysed for their content of nitrite. Nitrite content was quite different both between different food categories and within the same food category, ranging from not determined (n.d.) to 19.7 mg kg(-1). A great variation in the content of nitrite was found for all the food products. The average content of nitrite was highest in cured meat products (14.3 mg kg(-1)). Next to that, the nitrite content was high in the order of preserved vegetables (4.1 mg kg(-1)), soybean products (3.5 mg kg(-1)), and dairy products (1.9 mg kg(-1)). The lowest average values of nitrite were detected in soy sauce, rice and rice products, salt and fish products, the contents being 0.1, 0.3, 0.3, and 0.6 mg kg(-1). Calculations on the basis of these results and including dietary surveys show that the average intake of nitrite in north-east China from food was 0.03 mg kg(-1) body weight for an average Chinese person weighing 60 kg, and the data are lower than the established acceptable daily intake (ADI) for nitrite. Cured meat products are normally the major contributor to average nitrite intake of the north-east Chinese population. The second contributor is vegetables.

Optical biosensing of nitrite ions using cytochrome cd1 nitrite reductase encapsulated in a sol-gel matrix.

PubMed

Ferretti, S; Lee, S K; MacCraith, B D; Oliva, A G; Richardson, D J; Russell, D A; Sapsford, K E; Vidal, M

2000-11-01

Nitrite is an important human health and environmental analyte. As such, the European Union (EU) has imposed a limit for nitrite in potable water of 0.1 mg l-1 (2.18 microM). In order to develop an optical biosensing system for the determination of nitrite ions in environmental waters, cytochrome cd1 nitrite reductase has been extracted and purified from the bacterium Paracoccus pantotrophus. The protein has been spectroscopically characterised in solution and important kinetic parameters of nitrite reduction of the cytochrome cd1 enzyme, i.e., Km, Vmax and kcat have been determined. The influence of pH on the activity of the cytochrome cd1 has been investigated and the results suggest that this enzyme can be used for the determination of nitrite in the pH range 6-9. Biosensing experiments with the cytochrome cd1 in solution suggested that the decrease in intensity of the absorption band associated with the d1 haem (which is the nitrite binding site), at 460 nm, with increasing nitrite concentrations would enable the measurement of this analyte with the optimum limit of detection. The cytochrome cd1 has been encapsulated in a bulk sol-gel monolith with no structural changes observed and retention of enzymatic activity. The detection of nitrite ions in the range 0.075-1.250 microM was achieved, with a limit of detection of 0.075 microM. In order to increase the speed of response, a sol-gel sandwich thin film structure was formulated with the cytochrome cd1. This structure enabled the determination of nitrite concentrations within ca. 5 min. The sol-gel sandwich entrapped cytochrome cd1 enzyme was found to be stable for several months when the films were stored at 4 degrees C.

Mainstream upflow nitritation-anammox system with hybrid anaerobic pretreatment: Long-term performance and microbial community dynamics.

PubMed

Li, Xiaojin; Sun, Shan; Yuan, Heyang; Badgley, Brian D; He, Zhen

2017-11-15

Mainstream nitritation-anammox is of strong interest to energy- and resource-efficient domestic wastewater treatment. However, there lack in-depth studies of pretreatment, tests of actual wastewater, and examination of long-term performance. Herein, an upflow nitritation-anammox granular reactor has been investigated to treat primary effluent with a hybrid anaerobic reactor (HAR) as pretreatment for more than 300 days. This system achieved 92% of COD removal, 75% of which was accomplished by the HAR, and had an average final effluent COD concentration of 22 mg L -1 . More than 90% of ammonium was removed in the nitritation-anammox reactor, achieving a nitrogen removal rate of 81.0 g N m -3  d -1 in the last stage. The accumulation of sulfate-reducing bacteria in the HAR evidenced the effect of sulfate on COD removal and subsequent nitrogen removal. Anammox bacteria (predominantly Ca. Jettenia asiatica) accounted for up to 40.2% of total granular communities, but their abundance decreased over time in the suspended communities. The dynamics of major metabolisms and functional genes involved in nitrogen conversion were predicted by PICRUSt based on the taxonomic data, providing more insights into the functions of the microbial communities. These results have demonstrated the effectiveness and importance of anaerobic pretreatment to successful mainstream nitritation-anammox. Copyright © 2017 Elsevier Ltd. All rights reserved.

Consumer attitude and purchase intention towards processed meat products with natural compounds and a reduced level of nitrite.

PubMed

Hung, Yung; de Kok, Theo M; Verbeke, Wim

2016-11-01

This study investigates consumer attitude and purchase intention towards processed meat products with added natural compounds and a reduced level of nitrite. The rationale for such innovation relates to nitrite's negative health image as a chemical additive among consumers, versus the perception of compounds from fruits and vegetables as being natural and healthy. Cross-sectional data were collected through online questionnaires on knowledge about, interest in, attitude and intentions towards such new type of processed meat products in Belgium, The Netherlands, Italy and Germany (n=2057). Consumers generally had limited knowledge about nitrite being added to meat products. Yet, they expressed favourable attitudes and purchase intentions towards the new processed meat products. Purchase intention associated positively with: attitude; preference for natural over chemical additives; perceived harmfulness of chemical additives; risk importance; domain specific innovativeness; awareness of nitrite added; education; general health interest; and processed meat consumption frequency. Consumers from Italy and Germany had a lower level of purchase intention compared to Belgium. Four consumer segments were identified based on attitude and purchase intention: 'enthusiasts' (39.3% of the sample), 'accepters' (11.9%), 'half-hearted' (42.3%) and 'uninterested' (6.6%). This study provides valuable insight for further product development and effective tailoring of marketing communication strategies of innovative processed meat products. Copyright © 2016 Elsevier Ltd. All rights reserved.

Removal of PPCPs from the sludge supernatant in a one stage nitritation/anammox process.

PubMed

Alvarino, T; Suarez, S; Katsou, E; Vazquez-Padin, J; Lema, J M; Omil, F

2015-01-01

Pharmaceutical and personal care products (PPCPs) are extensively used and can therefore find their way into surface, groundwater and municipal and industrial effluents. In this work, the occurrence, fate and removal mechanisms of 19 selected PPCPs was investigated in an 'ELiminación Autótrofa de Nitrógeno' (ELAN) reactor of 200 L. In this configuration, ammonium oxidation to nitrite and the anoxic ammonium oxidation (anammox)processes occur simultaneously in a single-stage reactor under oxygen limited conditions. The ELAN process achieved high removal (>80%) of the studied hormones, naproxen, ibuprofen, bisphenol A and celestolide, while it was not effective in the removal of carbamazepine (<7%), diazepam (<7%) and fluoxetine (<30%). Biodegradation was the dominant removal mechanism, while sorption was only observed for musk fragrances, fluoxetine and triclosan. The sorption was strongly dependent on the granule size, with smaller granules facilitating the sorption of the target compounds. Increased hydraulic retention time enhanced the intramolecular diffusion of the PPCPs into the granules, and thus increased the solid phase concentration. The increase of nitritation rate favored the removal of ibuprofen, bisphenol A and triclosan, while the removal of erythromycin was strongly correlated to the anammox reaction rate.

Nitrate Reduction to Nitrite, Nitric Oxide and Ammonia by Gut Bacteria under Physiological Conditions

PubMed Central

Tiso, Mauro; Schechter, Alan N.

2015-01-01

The biological nitrogen cycle involves step-wise reduction of nitrogen oxides to ammonium salts and oxidation of ammonia back to nitrites and nitrates by plants and bacteria. Neither process has been thought to have relevance to mammalian physiology; however in recent years the salivary bacterial reduction of nitrate to nitrite has been recognized as an important metabolic conversion in humans. Several enteric bacteria have also shown the ability of catalytic reduction of nitrate to ammonia via nitrite during dissimilatory respiration; however, the importance of this pathway in bacterial species colonizing the human intestine has been little studied. We measured nitrite, nitric oxide (NO) and ammonia formation in cultures of Escherichia coli, Lactobacillus and Bifidobacterium species grown at different sodium nitrate concentrations and oxygen levels. We found that the presence of 5 mM nitrate provided a growth benefit and induced both nitrite and ammonia generation in E.coli and L.plantarum bacteria grown at oxygen concentrations compatible with the content in the gastrointestinal tract. Nitrite and ammonia accumulated in the growth medium when at least 2.5 mM nitrate was present. Time-course curves suggest that nitrate is first converted to nitrite and subsequently to ammonia. Strains of L.rhamnosus, L.acidophilus and B.longum infantis grown with nitrate produced minor changes in nitrite or ammonia levels in the cultures. However, when supplied with exogenous nitrite, NO gas was readily produced independently of added nitrate. Bacterial production of lactic acid causes medium acidification that in turn generates NO by non-enzymatic nitrite reduction. In contrast, nitrite was converted to NO by E.coli cultures even at neutral pH. We suggest that the bacterial nitrate reduction to ammonia, as well as the related NO formation in the gut, could be an important aspect of the overall mammalian nitrate/nitrite/NO metabolism and is yet another way in which the microbiome links diet and health. PMID:25803049

Normoxic Cyclic GMP-independent Oxidative Signaling by Nitrite Enhances Airway Epithelial Cell Proliferation and Wound Healing

PubMed Central

Wang, Ling; Frizzell, Sheila A.; Zhao, Xuejun; Gladwin, Mark T.

2013-01-01

The airway epithelium provides important barrier and host defense functions. Recent studies reveal that nitrite is an endocrine reservoir of nitric oxide (NO) bioactivity that is converted to NO by enzymatic reductases along the physiological oxygen gradient. Nitrite signaling has been described as NO dependent activation mediated by reactions with deoxygenated redox active hemoproteins, such as hemoglobin, myoglobin, neuroglobin, xanthine oxidoreductase (XO) and NO synthase at low pH and oxygen tension. However, nitrite can also be readily oxidized to nitrogen dioxide (NO2•) via heme peroxidase reactions, suggesting the existence of alternative oxidative signaling pathways for nitrite under normoxic conditions. In the present study we examined normoxic signaling effects of sodium nitrite on airway epithelial cell wound healing. In an in vitro scratch injury model under normoxia, we exposed cultured monolayers of human airway epithelial cells to various concentrations of sodium nitrite and compared responses to NO donor. We found sodium nitrite potently enhanced airway epithelium wound healing at physiological concentrations (from 1uM). The effect of nitrite was blocked by the NO and NO2• scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (c-PTIO). Interestingly, nitrite treatment did not increase cyclic guanosine monophosphate (cGMP) levels under these normoxic conditions, even in the presence of a phosphodiesterase 5 inhibitor, suggesting cGMP independent signaling. Consistent with an oxidative signaling pathway requiring hydrogen peroxide (H2O2)/heme peroxidase/NO2• signaling, the effects of nitrite were potentiated by superoxide dismutase (SOD) and low concentration H2O2, whereas inhibited completely by catalase, followed by downstream extracellular-signal-regulated kinase (ERK) 1/2 activation. Our data represent the first description of normoxic nitrite signaling on lung epithelial cell proliferation and wound healing and suggest novel oxidative signaling pathways involving nitrite-H2O2 reactions, possibly via the intermediary, NO2•. PMID:22425780

Modelling nitrite dynamics and associated feedback processes in the Benguela oxygen minimum zone

NASA Astrophysics Data System (ADS)

Mashifane, T. B.; Vichi, M.; Waldron, H. N.; Machu, E.; Garçonc, V.

2016-08-01

Understanding nitrite dynamics in oxygen minimum zones (OMZs) is a challenge as it represents an intermediary nitrogen species with a short turnover time. Nitrite is also reduced to nitrogen in OMZs, preventing its accumulation. This creates difficulties in detecting nitrite with colorimetric methods as concentrations may occur below detection limits in some regions. Nitrite concentrations are key to understanding intermediate nitrogen processes and their implication for nitrogen loss in OMZs. A coupled physical-biogeochemical model is applied in the Benguela OMZ to study nitrite dynamics and its associated feedback processes. Simulated results show occurrence of primary and secondary nitrite maxima in the Benguela shelf waters. The primary nitrite maxima in the Benguela are attributed to nitrification and nitrate assimilation as they occur in association with the nitracline. Secondary nitrite maxima accumulate in the Angola-Benguela Front (ABF) OMZ and are attributed to denitrification. The secondary nitrite maxima are consumed by anaerobic ammonium oxidation (anammox) off Walvis Bay. Nitrite maxima are restricted to the shelf off Walvis Bay and advected offshore in the ABF region. Interchanges between the poleward South Atlantic Central Water (SACW) and the equatorward, well-aerated Eastern South Atlantic Central Water (ESACW) drive the seasonality of nitrogen processes in the Benguela. Subsequent nitrite reduction in the Benguela OMZ leads to nitrous oxide production, with high concentrations occurring in the ABF region as a result of nitrification and denitrification. Off Walvis Bay, nitrous oxide production is low since nitrite is consumed by anammox. Nitrous oxide production occurs in thermocline, intermediate and deeper water masses in the ABF region. High N fluxes in the Benguela are attributed to nitrification as compared to anammox and denitrification. Results from this study demonstrate the role of intermediate nitrogen species in nitrogen feedback processes in the Benguela and can be applied in other regions.

Dietary nitrite and nitrate: a review of potential mechanisms of cardiovascular benefits

PubMed Central

Machha, Ajay

2012-01-01

Purpose In the last decade, a growing scientific and medical interest has emerged toward cardiovascular effects of dietary nitrite and nitrate; however, many questions concerning their mode of action(s) remain unanswered. In this review, we focus on multiple mechanisms that might account for potential cardiovascular beneficial effects of dietary nitrite and nitrate. Results Beneficial changes to cardiovascular health from dietary nitrite and nitrate might result from several mechanism(s) including their reduction into nitric oxide, improvement in endothelial function, vascular relaxation, and/or inhibition of the platelet aggregation. From recently obtained evidence, it appears that the longstanding concerns about the toxicity of oral nitrite or nitrate are overstated. Conclusion Dietary nitrite and nitrate may have cardiovascular protective effects in both healthy individuals and also those with cardiovascular disease conditions. A role for nitrite and nitrate in nitric oxide biosynthesis and/or in improving nitric oxide bioavailability may eventually provide a rationale for using dietary nitrite and nitrate supplementation in the treatment and prevention of cardiovascular diseases. PMID:21626413

Quality of water from shallow wells in the rice-growing area in southwestern Louisiana, 1999 through 2001

USGS Publications Warehouse

Tollett, Roland W.; Fendick, Robert B.

2004-01-01

In 1999-2001, the U.S. Geological Survey installed and sampled 27 shallow wells in the rice-growing area in southwestern Louisiana as part of the Acadian-Pontchartrain Study Unit of the National Water-Quality Assessment Program. The purpose of this report is to describe the waulity of water from shallow wells in the rice-growing area and to relate that water quality to natural and anthropogenic activities, particularly rice agriculture. Ground-water samples were analyzed for general ground-water properties and about 150 water-quality constituents, including major inorganic ions, trace elements, nutrients, dissolved organic carbon (DOC), pesticides, radon, chloroflourocarbons, and selected stable isotopes. Dissolved solids concentrations for 17 wells exceeded the U.S. Environmental Protection Agency secondary minimum containment level of 500 milligrams per liter (mg/L) for drinking water. Concentrations for major pesticides generally were less than the maximum contaminant levels for drinking water. Two major inorganic ions, sulfate and chloride, and two trace elements, iron and manganese, had concentrations that were greater than the secondary maximum containment levels. Three nutrient concentrations were greater than 2 mg/L, a level that might indicate contamination from human activities, and one nutrient concentration (that for nitrite plus nitrite as nitrogen) was greater than the maximum contaminant level of 10 mg/L for drinking water. The median concentration for DOC was 0.5 mg/L, indicating naturally-occurring DOC conditions in the study area. Thirteen pesticides and 7 pesticide degradation products were detected in 14 of the 27 wells sampled. Bentazon, 2, 4-D, and molinate (three rice herbicides) were detected in water from four, one, and one wells, respectively, and malathion (a rice insecticide) was deteced in water fromone well. Low-level concentrations and few detections of nutrients and pesticides indicated that ground-water quality was affected slightly by anthropogenic activities. Quality-control samples, including field blanks, replicates, and spikes, indicated no bias in ground-water data from collection on analysis. Radon concentrations for 22 of the 24 wells sampled wer at or greater than the U.S. Environmental Protection Agency proposed maximum contaminant level of 300 picocuries per liter. Chlorofluorocarbon concentrations in selected wells indicated the apparent ages of the ground water varied with depth water level and ranged from about 17 to 49 years. The stable isotopes of hydrogen and oxygen in water molecules indicated the origin of ground water in the study area was rainwater that originated near the study area and that few geochemical or physical processes influenced the stable isotopic composition of the shallow ground water. The Spearman rank correlation was used to detemrine whther significant correlations existed between physical properties, selected chemical constituents, the number of pesticides detected, and the apparent age of water. The depth to ground water was positively correlated to the well depth and inversely correlated to dissolved solids and other constituents, such as radon, indicating the ground water was under unconfined or semiconfined conditions and more dilute with increasing depth. As the depth to ground water increased, the concentrations of dissolved solids and other constituents decreased, possibly because the deeper sands had a greater transmittal of ground water, which, over time, would flush out, or dilute, the concentrations of dissolved solids in the natural sediments. The apparent age of water was correlated inversely with nitrite plus nitrite concentration, indicating that as apparent age increased, the nitrite plus nitrite concentration decreased. No significant correlations existed between the number of pesticides detected and any of the physical or chemica

Role of xanthine oxidoreductase in the anti-thrombotic effects of nitrite in rats in vivo.

PubMed

Kramkowski, K; Leszczynska, A; Przyborowski, K; Kaminski, T; Rykaczewska, U; Sitek, B; Zakrzewska, A; Proniewski, B; Smolenski, R T; Chabielska, E; Buczko, W; Chlopicki, S

2016-01-01

The mechanisms underlying nitrite-induced effects on thrombosis and hemostasis in vivo are not clear. The goal of the work described here was to investigate the role of xanthine oxidoreductase (XOR) in the anti-platelet and anti-thrombotic activities of nitrite in rats in vivo. Arterial thrombosis was induced electrically in rats with renovascular hypertension by partial ligation of the left renal artery. Sodium nitrite (NaNO2, 0.17 mmol/kg twice daily for 3 days, p.o) was administered with or without one of the XOR-inhibitors: allopurinol (ALLO) and febuxostat (FEB) (100 and 5 mg/kg, p.o., for 3 days). Nitrite treatment (0.17 mmol/kg), which was associated with a significant increase in NOHb, nitrite/nitrate plasma concentration, resulted in a substantial decrease in thrombus weight (TW) (0.48 ± 0.03 mg vs. vehicle [VEH] 0.88 ± 0.08 mg, p < 0.001) without a significant hypotensive effect. The anti-thrombotic effect of nitrite was partially reversed by FEB (TW = 0.63 ± 0.06 mg, p < 0.05 vs. nitrites), but not by ALLO (TW = 0.43 ± 0.02 mg). In turn, profound anti-platelet effect of nitrite measured ex vivo using collagen-induced whole-blood platelet aggregation (70.5 ± 7.1% vs. VEH 100 ± 4.5%, p < 0.05) and dynamic thromboxaneB2 generation was fully reversed by both XOR-inhibitors. In addition, nitrite decreased plasminogen activator inhibitor-1 concentration (0.47 ± 0.13 ng/ml vs. VEH 0.62 ± 0.04 ng/ml, p < 0.05) and FEB/ALLO reversed this effect. In vitro the anti-platelet effect of nitrite (1 mM) was reversed by FEB (0.1 mM) under hypoxia (0.5%O2) and normoxia (20%O2). Nitrite treatment had no effect on coagulation parameters. In conclusion, the nitrite-induced anti-platelet effect in rats in vivo is mediated by XOR, but XOR does not fully account for the anti-thrombotic effects of nitrite.

Trends in selected water-quality characteristics, Flathead River at Flathead, British Columbia, and at Columbia Falls, Montana, water years, 1975-86

USGS Publications Warehouse

Cary, L.E.

1989-01-01

Data for selected water quality variables were evaluated for trends at two sampling stations--Flathead River at Flathead, British Columbia (Flathead station) and Flathead River at Columbia Falls, Montana (Columbia Falls station). The results were compared between stations. The analyses included data from water years 1975-86 at the Flathead station and water years 1979-86 at the Columbia Falls station. The seasonal Kendall test was applied to adjusted concentrations for variables related to discharge and to unadjusted concentrations for the remaining variables. Slope estimates were made for variables with significant trends unless data were reported as less than the detection limit. At the Flathead station, concentrations of dissolved solids, calcium, magnesium, sodium, dissolved nitrite plus nitrate nitrogen, ammonia nitrogen (total and dissolved), total organic nitrogen, and total phosphorus increased during the study period. Concentrations of total nitrite plus nitrate nitrogen and dissolved iron decreased during the same period. At the Columbia Falls station, concentrations increased for calcium and magnesium and decreased for sulfate and dissolved phosphorus. No trends were detected for 10 other variables tested at each station. Data for the Flathead station were reanalyzed for water years 1979-86. Trends in the data increased for magnesium and dissolved nitrite plus nitrate nitrogen and decreased for dissolved iron. Magnesium was the only variable that displayed a trend (increasing) at both stations. The increasing trends that were detected probably will not adversely affect the water quality of the Flathead River in the near future. (USGS)

Nitrite formation from vegetable sources and its use as a preservative in cooked sausage.

PubMed

Ko, Young Mi; Park, Jin Hwa; Yoon, Ki Sun

2017-04-01

Due to the potential health risk associated with nitrites, nitrite alternatives from natural sources in meat products have been investigated. We compared the nitrate contents of young radish, lettuce and commercial vegetable powder (cabbage and Chinese cabbage). We also investigated the effect of incubation time and salt addition on vegetable nitrite formation from vegetable sources. The antioxidant and antimicrobial effects of vegetable nitrite in cooked sausage were also compared with sodium nitrite. Young radish produced the greatest amount of nitrite after 24 h of incubation at 38 °C. On average, an approximately 32% reduction of nitrite was observed in sausage during 4 weeks of storage. Lipid oxidation in sausage was significantly prevented by vegetable nitrite produced from vegetable powder or young radish. The colour of the sausage prepared with young radish was most similar to that of the sausage with sodium nitrite. The addition of young radish to sausage significantly prevented the growth of Listeria monocytogenes at 4 °C and Staphylococcus aureus at 8 °C. Young radish was more effective as a natural antioxidant and antimicrobial agent as compared to commercial vegetable powder, which is currently used to make natural meat products, indicating that young radish has a high potential as a natural preservative. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Genomics of a phototrophic nitrite oxidizer: insights into the evolution of photosynthesis and nitrification.

PubMed

Hemp, James; Lücker, Sebastian; Schott, Joachim; Pace, Laura A; Johnson, Jena E; Schink, Bernhard; Daims, Holger; Fischer, Woodward W

2016-11-01

Oxygenic photosynthesis evolved from anoxygenic ancestors before the rise of oxygen ~2.32 billion years ago; however, little is known about this transition. A high redox potential reaction center is a prerequisite for the evolution of the water-oxidizing complex of photosystem II. Therefore, it is likely that high-potential phototrophy originally evolved to oxidize alternative electron donors that utilized simpler redox chemistry, such as nitrite or Mn. To determine whether nitrite could have had a role in the transition to high-potential phototrophy, we sequenced and analyzed the genome of Thiocapsa KS1, a Gammaproteobacteria capable of anoxygenic phototrophic nitrite oxidation. The genome revealed a high metabolic flexibility, which likely allows Thiocapsa KS1 to colonize a great variety of habitats and to persist under fluctuating environmental conditions. We demonstrate that Thiocapsa KS1 does not utilize a high-potential reaction center for phototrophic nitrite oxidation, which suggests that this type of phototrophic nitrite oxidation did not drive the evolution of high-potential phototrophy. In addition, phylogenetic and biochemical analyses of the nitrite oxidoreductase (NXR) from Thiocapsa KS1 illuminate a complex evolutionary history of nitrite oxidation. Our results indicate that the NXR in Thiocapsa originates from a different nitrate reductase clade than the NXRs in chemolithotrophic nitrite oxidizers, suggesting that multiple evolutionary trajectories led to modern nitrite-oxidizing bacteria.

Hemoglobin as a nitrite anhydrase: modeling methemoglobin-mediated N2O3 formation.

PubMed

Hopmann, Kathrin H; Cardey, Bruno; Gladwin, Mark T; Kim-Shapiro, Daniel B; Ghosh, Abhik

2011-05-27

Nitrite has recently been recognized as a storage form of NO in blood and as playing a key role in hypoxic vasodilation. The nitrite ion is readily reduced to NO by hemoglobin in red blood cells, which, as it happens, also presents a conundrum. Given NO's enormous affinity for ferrous heme, a key question concerns how it escapes capture by hemoglobin as it diffuses out of the red cells and to the endothelium, where vasodilation takes place. Dinitrogen trioxide (N(2)O(3)) has been proposed as a vehicle that transports NO to the endothelium, where it dissociates to NO and NO(2). Although N(2)O(3) formation might be readily explained by the reaction Hb-Fe(3+)+NO(2)(-)+NO⇌Hb-Fe(2+)+N(2)O(3), the exact manner in which methemoglobin (Hb-Fe(3+)), nitrite and NO interact with one another is unclear. Both an "Hb-Fe(3+)-NO(2)(-)+NO" pathway and an "Hb-Fe(3+)-NO+NO(2)(-) " pathway have been proposed. Neither pathway has been established experimentally. Nor has there been any attempt until now to theoretically model N(2)O(3) formation, the so-called nitrite anhydrase reaction. Both pathways have been examined here in a detailed density functional theory (DFT, B3LYP/TZP) study and both have been found to be feasible based on energetics criteria. Modeling the "Hb-Fe(3+)-NO(2)(-)+NO" pathway proved complex. Not only are multiple linkage-isomeric (N- and O-coordinated) structures conceivable for methemoglobin-nitrite, multiple isomeric forms are also possible for N(2)O(3) (the lowest-energy state has an N-N-bonded nitronitrosyl structure, O(2)N-NO). We considered multiple spin states of methemoglobin-nitrite as well as ferromagnetic and antiferromagnetic coupling of the Fe(3+) and NO spins. Together, the isomerism and spin variables result in a diabolically complex combinatorial space of reaction pathways. Fortunately, transition states could be successfully calculated for the vast majority of these reaction channels, both M(S)=0 and M(S)=1. For a six-coordinate Fe(3+)-O-nitrito starting geometry, which is plausible for methemoglobin-nitrite, we found that N(2)O(3) formation entails barriers of about 17-20 kcal mol(-1) , which is reasonable for a physiologically relevant reaction. For the "Hb-Fe(3+) -NO+NO(2) (-) " pathway, which was also found to be energetically reasonable, our calculations indicate a two-step mechanism. The first step involves transfer of an electron from NO(2)(-) to the Fe(3+)-heme-NO center ({FeNO}(6)) , resulting in formation of nitrogen dioxide and an Fe(2+)-heme-NO center ({FeNO}(7)). Subsequent formation of N(2)O(3) entails a barrier of only 8.1 kcal mol(-1) . From an energetics point of view, the nitrite anhydrase reaction thus is a reasonable proposition. Although it is tempting to interpret our results as favoring the "{FeNO}(6)+NO(2)(-) " pathway over the "Fe(3+)-nitrite+NO" pathway, both pathways should be considered energetically reasonable for a biological reaction and it seems inadvisable to favor a unique reaction channel based solely on quantum chemical modeling. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Estimation of nitrite in source-separated nitrified urine with UV spectrophotometry.

PubMed

Mašić, Alma; Santos, Ana T L; Etter, Bastian; Udert, Kai M; Villez, Kris

2015-11-15

Monitoring of nitrite is essential for an immediate response and prevention of irreversible failure of decentralized biological urine nitrification reactors. Although a few sensors are available for nitrite measurement, none of them are suitable for applications in which both nitrite and nitrate are present in very high concentrations. Such is the case in collected source-separated urine, stabilized by nitrification for long-term storage. Ultraviolet (UV) spectrophotometry in combination with chemometrics is a promising option for monitoring of nitrite. In this study, an immersible in situ UV sensor is investigated for the first time so to establish a relationship between UV absorbance spectra and nitrite concentrations in nitrified urine. The study focuses on the effects of suspended particles and saturation on the absorbance spectra and the chemometric model performance. Detailed analysis indicates that suspended particles in nitrified urine have a negligible effect on nitrite estimation, concluding that sample filtration is not necessary as pretreatment. In contrast, saturation due to very high concentrations affects the model performance severely, suggesting dilution as an essential sample preparation step. However, this can also be mitigated by simple removal of the saturated, lower end of the UV absorbance spectra, and extraction of information from the secondary, weaker nitrite absorbance peak. This approach allows for estimation of nitrite with a simple chemometric model and without sample dilution. These results are promising for a practical application of the UV sensor as an in situ nitrite measurement in a urine nitrification reactor given the exceptional quality of the nitrite estimates in comparison to previous studies. Copyright © 2015 Elsevier Ltd. All rights reserved.

Nitrogen transformation under different dissolved oxygen levels by the anoxygenic phototrophic bacterium Marichromatium gracile.

PubMed

Hong, Xuan; Chen, Zhongwei; Zhao, Chungui; Yang, Suping

2017-06-01

Marichromatium gracile: YL28 (M. gracile YL28) is an anoxygenic phototrophic bacterial strain that utilizes ammonia, nitrate, or nitrite as its sole nitrogen source during growth. In this study, we investigated the removal and transformation of ammonium, nitrate, and nitrite by M. gracile YL28 grown in a combinatorial culture system of sodium acetate-ammonium, sodium acetate-nitrate and sodium acetate-nitrite in response to different initial dissolved oxygen (DO) levels. In the sodium acetate-ammonium system under aerobic conditions (initial DO = 7.20-7.25 mg/L), we detected a continuous accumulation of nitrate and nitrite. However, under semi-anaerobic conditions (initial DO = 4.08-4.26 mg/L), we observed a temporary accumulation of nitrate and nitrite. Interestingly, under anaerobic conditions (initial DO = 0.36-0.67 mg/L), there was little accumulation of nitrate and nitrite, but an increase in nitrous oxide production. In the sodium acetate-nitrite system, nitrite levels declined slightly under aerobic conditions, and nitrite was completely removed under semi-anaerobic and anaerobic conditions. In addition, M. gracile YL28 was able to grow using nitrite as the sole nitrogen source in situations when nitrogen gas produced by denitrification was eliminated. Taken together, the data indicate that M. gracile YL28 performs simultaneous heterotrophic nitrification and denitrification at low-DO levels and uses nitrite as the sole nitrogen source for growth. Our study is the first to demonstrate that anoxygenic phototrophic bacteria perform heterotrophic ammonia-oxidization and denitrification under anaerobic conditions.

Role of aldehyde dehydrogenase in hypoxic vasodilator effects of nitrite in rats and humans

PubMed Central

Arif, Sayqa; Borgognone, Alessandra; Lin, Erica Lai-Sze; O'Sullivan, Aine G; Sharma, Vishal; Drury, Nigel E; Menon, Ashvini; Nightingale, Peter; Mascaro, Jorge; Bonser, Robert S; Horowitz, John D; Feelisch, Martin; Frenneaux, Michael P; Madhani, Melanie

2015-01-01

Background and Purpose Hypoxic conditions favour the reduction of nitrite to nitric oxide (NO) to elicit vasodilatation, but the mechanism(s) responsible for bioconversion remains ill defined. In the present study, we assess the role of aldehyde dehydrogenase 2 (ALDH2) in nitrite bioactivation under normoxia and hypoxia in the rat and human vasculature. Experimental Approach The role of ALDH2 in vascular responses to nitrite was studied using rat thoracic aorta and gluteal subcutaneous fat resistance vessels from patients with heart failure (HF; 16 patients) in vitro and by measurement of changes in forearm blood flow (FBF) during intra-arterial nitrite infusion (21 patients) in vivo. Specifically, we investigated the effects of (i) ALDH2 inhibition by cyanamide or propionaldehyde and the (ii) tolerance-independent inactivation of ALDH2 by glyceryl trinitrate (GTN) on the vasodilator activity of nitrite. In each setting, nitrite effects were measured via evaluation of the concentration–response relationship under normoxic and hypoxic conditions in the absence or presence of ALDH2 inhibitors. Key Results Both in rat aorta and human resistance vessels, dilatation to nitrite was diminished following ALDH2 inhibition, in particular under hypoxia. In humans there was a non-significant trend towards attenuation of nitrite-mediated increases in FBF. Conclusions and Implications In human and rat vascular tissue in vitro, hypoxic nitrite-mediated vasodilatation involves ALDH2. In patients with HF in vivo, the role of this enzyme in nitrite bioactivation is at the most, modest, suggesting the involvement of other more important mechanisms. PMID:25754766

Periodontal Therapy Effects on Nitrite Related to Oral Bacteria: A 6-Month Randomized Clinical Trial.

PubMed

Cortelli, Sheila C; Costa, Fernando O; Rodrigues, Edson; Cota, Luis O M; Cortelli, Jose R

2015-08-01

Nitrite is a biologic factor relevant to oral and systemic homeostasis. Through an oral bacteria reduction process, it was suggested that periodontal therapy and chlorhexidine (CHX) rinse could affect nitrite levels, leading to negative effects, such as an increase in blood pressure. This 6-month randomized clinical trial evaluated the effects of periodontal therapeutic protocols on salivary nitrite and its relation to subgingival bacteria. One hundred patients with periodontitis were allocated randomly to debridement procedures in four weekly sections (quadrant scaling [QS]) or within 24 hours (full-mouth scaling [FMS]) in conjunction with a 60-day CHX (QS + CHX and FMS + CHX), placebo (QS + placebo and FMS + placebo), or no mouthrinse (QS + none and FMS + none) use. Real-time polymerase chain reaction determined total bacterial, Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola, Streptococcus oralis, and Actinomyces naeslundii levels. Salivary nitrite concentration was determined with Griess reagent. Data were analyzed statistically at baseline and 3 and 6 months by analysis of variance, Kruskal-Wallis, Mann-Whitney U, and Spearman correlation tests (P <0.05). Nitrite concentrations did not tend to change over time. Regarding CHX use, there was a negative correlation between nitrite and total bacterial load at 6 months (FMS + CHX) and one positive correlation between P. gingivalis and nitrite at baseline (QS + CHX). Independently of rinse type, in the FMS group, nitrite correlated negatively with several microbial parameters and also with a higher percentage of deep periodontal pockets. The relationship between nitrite and bacterial levels appears weak. Short-term scaling exhibited a greater influence on nitrite concentrations then long-term CHX use.

75 FR 29534 - Inorganic Nitrates-Nitrite, Carbon and Carbon Dioxide, and Sulfur Registration Review; Draft...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-26

... ENVIRONMENTAL PROTECTION AGENCY [EPA-HQ-OPP-2010-0434; FRL-8826-6] Inorganic Nitrates-Nitrite... for the registration review of inorganic nitrates - nitrites, carbon and carbon dioxide, and gas... identifies those species for which exposure and effects may occur for all inorganic nitrates- nitrites...

A comparison of blood nitric oxide metabolites and hemoglobin functional properties among diving mammals.

PubMed

Fago, Angela; Parraga, Daniel Garcia; Petersen, Elin E; Kristensen, Niels; Giouri, Lea; Jensen, Frank B

2017-03-01

The ability of marine mammals to hunt prey at depth is known to rely on enhanced oxygen stores and on selective distribution of blood flow, but the molecular mechanisms regulating blood flow and oxygen transport remain unresolved. To investigate the molecular mechanisms that may be important in regulating blood flow, we measured concentration of nitrite and S-nitrosothiols (SNO), two metabolites of the vasodilator nitric oxide (NO), in the blood of 5 species of marine mammals differing in their dive duration: bottlenose dolphin, South American sea lion, harbor seal, walrus and beluga whale. We also examined oxygen affinity, sensitivity to 2,3-diphosphoglycerate (DPG) and nitrite reductase activity of the hemoglobin (Hb) to search for possible adaptive variations in these functional properties. We found levels of plasma and red blood cells nitrite similar to those reported for terrestrial mammals, but unusually high concentrations of red blood cell SNO in bottlenose dolphin, walrus and beluga whale, suggesting enhanced SNO-dependent signaling in these species. Purified Hbs showed similar functional properties in terms of oxygen affinity and sensitivity to DPG, indicating that reported large variations in blood oxygen affinity among diving mammals likely derive from phenotypic variations in red blood cell DPG levels. The nitrite reductase activities of the Hbs were overall slightly higher than that of human Hb, with the Hb of beluga whale, capable of longest dives, having the highest activity. Taken together, these results underscore adaptive variations in circulatory NO metabolism in diving mammals but not in the oxygenation properties of the Hb. Copyright © 2016 Elsevier Inc. All rights reserved.

[A novel bacterium carrying out anaerobic ammonium oxidation in a reactor for biological treatment of the filtrate of wastewater fermented residue].

PubMed

Khramenkov, S V; Kozlov, M N; Krevbona, M V; Drofeev, A G; Kazakova, E A; Grachev, V A; Kuznetsov, B B; Poliakov, D Iu; Nikolaev, Iu A

2013-01-01

A new genus and species of bacteria capable of ammonium oxidation under anaerobic conditions in the presence of nitrite is described. The enrichment culture was obtained from the Moscow River silt by sequential cultivation in reactors with selective conditions for anaerobic ammonium oxidation. Bacterial cells were coccoid, -0.4 x 0.7 mm, with the intracellular membrane structures typical of bacteria capable of anaerobic ammonium oxidation (anammoxosome and paryphoplasm). The cells formed aggregates 5-25 μm in diameter (10 μm on average). They were readily adhered to solid surfaces. The cells were morphologically labile, they easily lost their content and changed their morphology during fixation for electron microscopy. The organism was capable of ammonium oxidation with nitrite. The semisaturation constants Ks for nitrite and ammonium were 0.38 mg N-NO2/L and 0.41 mg N-NH4/L, respectively. The maximal nitrite concentrations for growth were 90 and 75 mg N-NO2/L for single and continuous application, respectively. The doubling time was 32 days, μ(max) = 0.022 day(-1), the optimal temperature and pH were 20 degrees C and 7.8-8.3, respectively. According to the 16S rRNA gene sequencing, the bacterium was assigned to a new genus and species within the phylum Planctomycetes. The proposed name for the new bacterium is Candidatus Anammoximicrobium moscowii gen. nov., sp. nov. (a microorganisms carrying out anaerobia ammonium oxidation, isolated in the Moscow region).

Automated, colorimetric methods for determination of nitrate plus nitrite, nitrite, ammonium and orthophosphate ions in natural water samples

USGS Publications Warehouse

Antweiler, Ronald C.; Patton, Charles J.; Taylor, Howard E.

1996-01-01

The apparatus and methods used for the automatic, colorimetric determinations of dissolved nutrients (nitrate plus nitrite, nitrite, ammonium and orthophosphate) in natural waters are described. These techniques allow for the determination of nitrate plus nitrite for the concentration range 0.02 to 8 mg/L (milligrams per liter) as N (nitrogen); for nitrite, the range is 0.002 to 1.0 mg/L as N; for ammonium, the range is 0.006 to 2.0 mg/L as N; and for orthophosphate, the range is 0.002 to 1.0 mg/L as P (phosphorus). Data are presented that demonstrate the accuracy, precision and quality control of the methods.

Evolution of nitrate and nitrite during the processing of dry-cured ham with partial replacement of NaCl by other chloride salts.

PubMed

Armenteros, Mónica; Aristoy, María-Concepción; Toldrá, Fidel

2012-07-01

Nitrate and nitrite are commonly added to dry-cured ham to provide protection against pathogen microorganisms, especially Clostridium botulinum. Both nitrate and nitrite were monitored with ion chromatography in dry-cured hams salted with different NaCl formulations (NaCl partially replaced by KCl and/or CaCl(2), and MgCl(2)). Nitrate, that is more stable than nitrite, diffuses into the ham and acts as a reservoir for nitrite generation. A correct nitrate and nitrite penetration was detected from the surface to the inner zones of the hams throughout its processing, independently of the salt formulation. Nitrate and nitrite achieved similar concentrations, around 37 and 2.2 ppm, respectively in the inner zones of the ham for the three assayed salt formulations at the end of the process, which are in compliance with European regulations. Copyright © 2012 Elsevier Ltd. All rights reserved.

[Evaluation of nitrites and nitrates food intake in the students' group].

PubMed

Wawrzyniak, Agata; Hamułka, Jadwiga; Pankowska, Iwona

2010-01-01

The aim of study was to determine the intake of nitrites and nitrates in daily food rations of the students' group in 2008 using 3-day dietary food records method and literature mean values of nitrates and nitrites in food products. Intakes of these compounds were calculated and compared to acceptable daily intake (ADI). The average intake of nitrites was 1.7 mg NaNO2/per person/day (28.0% of ADI), nitrates 77.3 mg NaNO3/per person/day that means 25.4% of ADI. The largest nitrites food intake was noticed for meat products supplied 56.5% of nitrites and cereals (20%). Whereas vegetables and their products supplied 76.1% of nitrates: potatoes 17.1%, cabbage 15.5%, beetroots 13.7%. Calculated nitrites intake for men was 2.4 higher than for women. There were no significant differences of nitrates intake between men and women groups.

78 FR 68474 - Sodium Nitrite From China And Germany; Scheduling of Expedited Five-Year Reviews Concerning the...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-11-14

...)] Sodium Nitrite From China And Germany; Scheduling of Expedited Five-Year Reviews Concerning the Countervailing Duty Order and Antidumping Duty Order on Sodium Nitrite From China and the Antidumping Duty Order on Sodium Nitrite From Germany AGENCY: United States International Trade Commission. ACTION: Notice...

21 CFR 172.175 - Sodium nitrite.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Sodium nitrite. 172.175 Section 172.175 Food and... PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Food Preservatives § 172.175 Sodium nitrite. The food additive sodium nitrite may be safely used in or on specified foods in accordance with the...

Effect of six different starter cultures on the concentration of residual nitrite in fermented sausages during in vitro human digestion.

PubMed

Kim, Hyeong Sang; Hur, Sun Jin

2018-01-15

The objective of this study was to determine the effect of six different starter cultures of enterobacteria on the concentration of residual nitrite in fermented sausages during in vitro human digestion. Before digestion, the concentration of residual nitrite was dependent on starter culture in fermented sausage and ranged from 25.2 to 33.2mg/kg. Among the six starter cultures of enterobacteria, Pediococcus acidilactici, Pediococcus pentosaceus, and Staphylococcus carnosus showed higher nitrite depletion ability than the other three strains in fermented sausages. The concentration of residual nitrite in fermented sausages was significantly (p<0.05) decreased after stomach digestion and ranged from 17.4 to 21.6mg/kg. Enterobacteria Escherichia coli (E. coli) and/or Lactobacillus casei (L. casei) effectively increased the degree of depletion of residual nitrite in large intestine digestion. In conclusion, starter cultures could influence the concentration of residual nitrite during in vitro human digestion. They could deplete residual nitrite in fermented sausages. Copyright © 2017 Elsevier Ltd. All rights reserved.

Use of nitrite inhalants ("poppers") among American youth.

PubMed

Wu, Li-Tzy; Schlenger, William E; Ringwalt, Chris L

2005-07-01

We examined the patterns and correlates of nitrite inhalant use among adolescents aged 12 to 17 years. Study data were drawn from the 2000 and 2001 National Household Surveys on Drug Abuse. Logistic regression was used to identify the characteristics associated with nitrite inhalant use. Among adolescents aged 12 to 17 years, 1.5% reported any lifetime use of nitrite inhalants. The prevalence of lifetime nitrite inhalant use increased to 12% and 14% among adolescents who were dependent on alcohol and any drug in the past year, respectively. Many nitrite inhalant users used at least three other types of inhalants (68%) and also met the criteria for alcohol (33%) and drug (35%) abuse or dependence. Increased odds of nitrite inhalant use were associated with residing in nonmetropolitan areas, recent utilization of mental health services, delinquent behaviors, past year alcohol and drug abuse and dependence, and multi-drug use. Adolescents who had used nitrite inhalants at least once in their lifetime tend to engage in delinquent activities and report co-occurring multiple drug abuse and mental health problems in the past year.

Modification of nitrifying biofilm into nitritating one by combination of increased free ammonia concentrations, lowered HRT and dissolved oxygen concentration.

PubMed

Zekker, Ivar; Rikmann, Ergo; Tenno, Toomas; Menert, Anne; Lemmiksoo, Vallo; Saluste, Alar; Tenno, Taavo; Tomingas, Martin

2011-01-01

Nitrifying biomass on ring-shaped carriers was modified to nitritating one in a relatively short period of time (37 days) by limiting the air supply, changing the aeration regime, shortening the hydraulic retention time and increasing free ammonia (FA) concentration in the moving-bed biofilm reactor (MBBR). The most efficient strategy for the development and maintenance of nitritating biofilm was found to be the inhibition of nitrifying activity by higher FA concentrations (up to 6.5 mg/L) in the process. Reject water from sludge treatment from the Tallinn Wastewater Treatment Plant was used as substrate in the MBBR. The performance of high-surfaced biocarriers taken from the nitritating activity MBBR was further studied in batch tests to investigate nitritation and nitrification kinetics with various FA concentrations and temperatures. The maximum nitrite accumulation ratio (96.6%) expressed as the percentage of NO2(-)-N/NOx(-)-N was achieved for FA concentration of 70 mg/L at 36 degrees C. Under the same conditions the specific nitrite oxidation rate achieved was 30 times lower than the specific nitrite formation rate. It was demonstrated that in the biofilm system, inhibition by FA combined with the optimization of the main control parameters is a good strategy to achieve nitritating activity and suppress nitrification.

Implications of Decreased Nitrite Concentrations on Clostridium perfringens Outgrowth during Cooling of Ready-to-Eat Meats.

PubMed

Myers, Megan I; Sebranek, Joseph G; Dickson, James S; Shaw, Angela M; Tarté, Rodrigo; Adams, Kristin R; Neibuhr, Steve

2016-01-01

Increased popularity of natural and organic processed meats can be attributed to the growing consumer demand for preservative-free foods, including processed meats. To meet this consumer demand, meat processors have begun using celery juice concentrate in place of sodium nitrite to create products labeled as no-nitrate or no-nitrite-added meat products while maintaining the characteristics unique to conventionally cured processed meats. Because of flavor limitations, natural cures with celery concentrate typically provide lower ingoing nitrite concentrations for ready-to-eat processed meats than do conventional cures, which could allow for increased growth of pathogens, such as Clostridium perfringens, during cooked product cooling such as that required by the U.S. Department of Agriculture. The objective of this study was to investigate the implications associated with reduced nitrite concentrations for preventing C. perfringens outgrowth during a typical cooling cycle used for cooked products. Nitrite treatments of 0, 50, and 100 ppm were tested in a broth system inoculated with a three-strain C. perfringens cocktail and heated with a simulated product thermal process followed by a typical cooling-stabilization process. The nitrite concentration of 50 ppm was more effective for preventing C. perfringens outgrowth than was 0 ppm but was not as effective as 100 ppm. The interaction between nitrite and temperature significantly affected (P < 0.05) C. perfringens outgrowth in both total population and number of vegetative cells. Both temperature and nitrite concentration significantly affected (P < 0.05) C. perfringens spore survival, but the interaction between nitrite and temperature did not have a significant effect (P > 0.05) on spore outgrowth. Results indicate that decreased nitrite concentrations (50 ppm) have increased potential for total C. perfringens population outgrowth during cooling and may require additional protective measures, such as faster chilling rates.

Inhibitory effects of nitrite on the reactions of bovine carbonic anhydrase II with CO2 and bicarbonate consistent with zinc-bound nitrite.

PubMed

Nielsen, Per M; Fago, Angela

2015-08-01

Carbonic anhydrase (CA) is a zinc enzyme that catalyzes hydration of carbon dioxide (CO2) and dehydration of bicarbonate in red blood cells, thus facilitating CO2 transport and excretion. Bovine CA II may also react with nitrite to generate nitric oxide, although nitrite is a known inhibitor of the CO2 hydration reaction. To address the potential in vivo interference of these reactions and the nature of nitrite binding to the enzyme, we here investigate the inhibitory effect of 10-30 mM nitrite on Michaelis-Menten kinetics of CO2 hydration and bicarbonate dehydration by stopped-flow spectroscopy. Our data show that nitrite significantly affects the apparent dissociation constant KM for CO2 (11 mM) and bicarbonate (221 mM), and the turnover number kcat for the CO2 hydration (1.467 × 10(6) s(-1)) but not for the bicarbonate dehydration (7.927 × 10(5) s(-1)). These effects demonstrate mixed and competitive inhibition for the reaction with CO2 and bicarbonate, respectively, and are consistent with nitrite binding to the active site zinc. The high apparent dissociation constant found here for CO2, bicarbonate and nitrite (16-120 mM) are all overall consistent with published data and reveal a large capacity of free enzyme available for binding each of the three substrates at their in vivo levels, with little or no significant interference among reactions. The low affinity of the enzyme for nitrite suggests that the in vivo interaction between red blood cell CA II and nitrite requires compartmentalization at the anion exchanger protein of the red cell membrane to be physiologically relevant. Copyright © 2015 Elsevier Inc. All rights reserved.

Nitrite exerts antioxidant effects, inhibits the mTOR pathway and reverses hypertension-induced cardiac hypertrophy.

PubMed

Guimaraes, Danielle A; Dos Passos, Madla A; Rizzi, Elen; Pinheiro, Lucas C; Amaral, Jefferson H; Gerlach, Raquel F; Castro, Michele M; Tanus-Santos, Jose E

2018-05-20

Cardiac hypertrophy is a common consequence of chronic hypertension and leads to heart failure and premature death. The anion nitrite is now considered as a bioactive molecule able to exert beneficial cardiovascular effects. Previous results showed that nitrite attenuates hypertension-induced increases in reactive oxygen species (ROS) production in the vasculature. Whether antioxidant effects induced by nitrite block critical signaling pathways involved in cardiac hypertrophy induced by hypertension has not been determined yet. The Akt/mTOR signaling pathway is responsible to activate protein synthesis during cardiac remodeling and is activated by increased ROS production, which is commonly found in hypertension. Here, we investigated the effects of nitrite treatment on cardiac remodeling and activation of this hypertrophic signaling pathway in 2 kidney-1 clip (2K1C) hypertension. Sham and 2K1C rats were treated with oral nitrite at 1 or 15 mg/kg for four weeks. Nitrite treatment (15 mg/kg) reduced systolic blood pressure and decreased ROS production in the heart tissue from hypertensive rats. This nitrite dose also blunted hypertension-induced activation of mTOR pathway and cardiac hypertrophy. While the lower nitrite dose (1 mg/kg) did not affect blood pressure, it exerted antioxidant effects and tended to attenuate mTOR pathway activation and cardiac hypertrophy induced by hypertension. Our findings provide strong evidence that nitrite treatment decreases cardiac remodeling induced by hypertension as a result of its antioxidant effects and downregulation of mTOR signaling pathway. This study may help to establish nitrite as an effective therapy in hypertension-induced cardiac hypertrophic remodeling. Copyright © 2018 Elsevier Inc. All rights reserved.

Characterization of nitrite degradation by Lactobacillus casei subsp. rhamnosus LCR 6013.

PubMed

Liu, Dong-mei; Wang, Pan; Zhang, Xin-yue; Xu, Xi-lin; Wu, Hui; Li, Li

2014-01-01

Nitrites are potential carcinogens. Therefore, limiting nitrites in food is critically important for food safety. The nitrite degradation capacity of Lactobacillus casei subsp. rhamnosus LCR 6013 was investigated in pickle fermentation. After LCR 6013 fermentation for 120 h at 37°C, the nitrite concentration in the fermentation system was significantly lower than that in the control sample without the LCR 6013 strain. The effects of NaCl and Vc on nitrite degradation by LCR 6013 in the De Man, Rogosa and Sharpe (MRS) medium were also investigated. The highest nitrite degradations, 9.29 mg/L and 9.89 mg/L, were observed when NaCl and Vc concentrations were 0.75% and 0.02%, respectively in the MRS medium, which was significantly higher than the control group (p ≤ 0.01). Electron capture/gas chromatography and indophenol blue staining were used to study the nitrite degradation pathway of LCR 6013. The nitrite degradation products contained N2O, but no NH4(+). The LCR 6013 strain completely degraded all NaNO2 (50.00 mg/L) after 16 h of fermentation. The enzyme activity of NiR in the periplasmic space was 2.5 times of that in the cytoplasm. Our results demonstrated that L. casei subsp. rhamnosus LCR 6013 can effectively degrade nitrites in both the pickle fermentation system and in MRS medium by NiR. Nitrites are degraded by the LCR 6013 strain, likely via the nitrate respiration pathway (NO2(-)>NO->N2O->N2), rather than the aammonium formation pathway (dissimilatory nitrate reduction to ammonium, DNRA), because the degradation products contain N2O, but not NH4(+).

Post Chlorine gas exposure administration of nitrite prevents lung injury: effect of administration modality

PubMed Central

Samal, Andrey A.; Honavar, Jaideep; Brandon, Angela; Bradley, Kelley M.; Doran, Stephen; Liu, Yanping; Dunaway, Chad; Steele, Chad; Postlethwait, Edward M.; Squadrito, Giuseppe L.; Fanucchi, Michelle V.; Matalon, Sadis; Patel, Rakesh P.

2012-01-01

Cl2 gas toxicity is complex and occurs during, and post exposure leading to acute lung injury (ALI) and reactive airway syndrome (RAS). Moreover, Cl2 exposure can occur in diverse situations encompassing mass casualty scenarios underscoring the need for post-exposure therapies that are efficacious and amenable to rapid and easy administration. In this study, we compared the efficacy of a single dose, post (30min) Cl2 exposure administration of nitrite (1mg/kg) via intraperitoneal (IP) or intramuscular (IM) injection in rats, to decrease ALI. Exposure of rats to Cl2 gas (400ppm, 30min) significantly increased ALI and caused RAS 6–24h post exposure as indexed by BAL sampling of lung surface protein, PMN and increased airway resistance and elastance prior to and post methacholine challenge. IP nitrite decreased Cl2 - dependent increases in BAL protein but not PMN. In contrast IM nitrite decreased BAL PMN levels without decreasing BAL protein in a xanthine oxidoreductase independent manner. Histological evaluation of airways 6h post exposure showed significant bronchial epithelium exfoliation and inflammatory injury in Cl2 exposed rats. Both IP and IM nitrite improved airway histology compared to Cl2 gas alone, but more coverage of the airway by cuboidal or columnar epithelium was observed with IM compared to IP nitrite. Airways were rendered more sensitive to methacholine induced resistance and elastance after Cl2 gas exposure. Interestingly, IM nitrite, but not IP nitrite, significantly decreased airway sensitivity to methacholine challenge. Further evaluation and comparison of IM and IP therapy showed a two-fold increase in circulating nitrite levels with the former, which was associated with reversal of post-Cl2 exposure dependent increases in circulating leukocytes. Halving the IM nitrite dose resulted in no effect in PMN accumulation but significant reduction of of BAL protein levels indicating distinct nitrite dose dependence for inhibition of Cl2 dependent lung permeability and inflammation. These data highlight the potential for nitrite as a post-exposure therapeutic for Cl2 gas induced lung injury and also suggest that administration modality is a key consideration in nitrite therapeutics. PMID:22917977

Strategies of Nitrosomonas europaea 19718 to counter low dissolved oxygen and high nitrite concentrations.

PubMed

Yu, Ran; Chandran, Kartik

2010-03-04

Nitrosomonas europaea is a widely studied chemolithoautotrophic ammonia oxidizing bacterium. While significant work exists on the ammonia oxidation pathway of N. europaea, its responses to factors such as dissolved oxygen limitation or sufficiency or exposure to high nitrite concentrations, particularly at the functional gene transcription level are relatively sparse. The principal goal of this study was to investigate responses at the whole-cell activity and gene transcript levels in N. europaea 19718 batch cultures, which were cultivated at different dissolved oxygen and nitrite concentrations. Transcription of genes coding for principal metabolic pathways including ammonia oxidation (amoA), hydroxylamine oxidation (hao), nitrite reduction (nirK) and nitric oxide reduction (norB) were quantitatively measured during batch growth, at a range of DO concentrations (0.5, 1.5 and 3.0 mg O2/L). Measurements were also conducted during growth at 1.5 mg O2/L in the presence of 280 mg-N/L of externally added nitrite. Several wide ranging responses to DO limitation and nitrite toxicity were observed in N. europaea batch cultures. In contrast to our initial hypothesis, exponential phase mRNA concentrations of both amoA and hao increased with decreasing DO concentrations, suggesting a mechanism to metabolize ammonia and hydroxylamine more effectively under DO limitation. Batch growth in the presence of 280 mg nitrite-N/L resulted in elevated exponential phase nirK and norB mRNA concentrations, potentially to promote utilization of nitrite as an electron acceptor and to detoxify nitrite. This response was in keeping with our initial hypothesis and congruent with similar responses in heterotrophic denitrifying bacteria. Stationary phase responses were distinct from exponential phase responses in most cases, suggesting a strong impact of ammonia availability and metabolism on responses to DO limitation and nitrite toxicity. In general, whole-cell responses to DO limitation or nitrite toxicity, such as sOUR or nitrite reduction to nitric oxide (NO) did not parallel the corresponding mRNA (nirK) profiles, suggesting differences between the gene transcription and enzyme translation or activity levels. The results of this study show that N. europaea possesses specific mechanisms to cope with growth under low DO concentrations and high nitrite concentrations. These mechanisms are additionally influenced by the physiological growth state of N. europaea cultures and are possibly geared to enable more efficient substrate utilization or nitrite detoxification.

THE REDUCTION OF NITRATE, NITRITE AND HYDROXYLAMINE TO AMMONIA BY ENZYMES FROM CUCURBITA PEPO L. IN THE PRESENCE OF REDUCED BENZYL VIOLOGEN AS ELECTRON DONOR.

PubMed

CRESSWELL, C F; HAGEMAN, R H; HEWITT, E J; HUCKLESBY, D P

1965-01-01

1. Enzyme systems from Cucurbita pepo have been shown to catalyse the reduction of nitrite and hydroxylamine to ammonia in yields about 90-100%. 2. Reduced benzyl viologen serves as an efficient electron donor for both systems. Activity of the nitrite-reductase system is directly related to degree of dye reduction when expressed in terms of the function for oxidation-reduction potentials, but appears to decrease to negligible activity below about 9% dye reduction. 3. NADH and NADPH alone produce negligible nitrite loss, but NADPH can be linked to an endogenous diaphorase system to reduce nitrite to ammonia in the presence of catalytic amounts of benzyl viologen. 4. The NADH- or NADPH-nitrate-reductase system that is also present can accept electrons from reduced benzyl viologen, but shows relationships opposite to that for the nitrite-reductase system with regard to effect of degree of dye reduction on activity. The product of nitrate reduction may be nitrite alone, or nitrite and ammonia, or ammonia alone, according only to the degree of dye reduction. 5. The relative activities of nitrite-reductase and hydroxylamine-reductase systems show different relationships with degree of dye reduction and may become reversed in magnitude when effects of degree of dye reduction are tested over a suitable range. 6. Nitrite severely inhibits the rate of reduction of hydroxylamine without affecting the yield of ammonia as a percentage of total substrate loss, but hydroxylamine has a negligible effect on the activity of the nitrite-reductase system. 7. The apparent K(m) for nitrite (1 mum) is substantially less than that for hydroxylamine, for which variable values between 0.05 and 0.9mm (mean 0.51 mm) have been observed. 8. The apparent K(m) values for reduced benzyl viologen differ for the nitrite-reductase and hydroxylamine-reductase systems: 60 and 7.5 mum respectively. 9. It is concluded that free hydroxylamine may not be an intermediate in the reduction of nitrite to ammonia by plants, and a possible mechanism for reduction of both compounds by the same enzyme system is discussed in the light of current ideas relating to other organisms.

The reduction of nitrate, nitrite and hydroxylamine to ammonia by enzymes from Cucurbita pepo L. in the presence of reduced benzyl viologen as electron donor

PubMed Central

Cresswell, C. F.; Hageman, R. H.; Hewitt, E. J.; Hucklesby, D. P.

1965-01-01

1. Enzyme systems from Cucurbita pepo have been shown to catalyse the reduction of nitrite and hydroxylamine to ammonia in yields about 90–100%. 2. Reduced benzyl viologen serves as an efficient electron donor for both systems. Activity of the nitrite-reductase system is directly related to degree of dye reduction when expressed in terms of the function for oxidation–reduction potentials, but appears to decrease to negligible activity below about 9% dye reduction. 3. NADH and NADPH alone produce negligible nitrite loss, but NADPH can be linked to an endogenous diaphorase system to reduce nitrite to ammonia in the presence of catalytic amounts of benzyl viologen. 4. The NADH– or NADPH–nitrate-reductase system that is also present can accept electrons from reduced benzyl viologen, but shows relationships opposite to that for the nitrite-reductase system with regard to effect of degree of dye reduction on activity. The product of nitrate reduction may be nitrite alone, or nitrite and ammonia, or ammonia alone, according only to the degree of dye reduction. 5. The relative activities of nitrite-reductase and hydroxylamine-reductase systems show different relationships with degree of dye reduction and may become reversed in magnitude when effects of degree of dye reduction are tested over a suitable range. 6. Nitrite severely inhibits the rate of reduction of hydroxylamine without affecting the yield of ammonia as a percentage of total substrate loss, but hydroxylamine has a negligible effect on the activity of the nitrite-reductase system. 7. The apparent Km for nitrite (1 μm) is substantially less than that for hydroxylamine, for which variable values between 0·05 and 0·9mm (mean 0·51 mm) have been observed. 8. The apparent Km values for reduced benzyl viologen differ for the nitrite-reductase and hydroxylamine-reductase systems: 60 and 7·5 μm respectively. 9. It is concluded that free hydroxylamine may not be an intermediate in the reduction of nitrite to ammonia by plants, and a possible mechanism for reduction of both compounds by the same enzyme system is discussed in the light of current ideas relating to other organisms. PMID:14342247

Nutrients, Select Pesticides, and Suspended Sediment in the Karst Terrane of the Sinking Creek Basin, Kentucky, 2004-06

USGS Publications Warehouse

Crain, Angela S.

2010-01-01

This report presents the results of a study by the U.S. Geological Survey, in cooperation with the Kentucky Department of Agriculture, on nutrients, select pesticides, and suspended sediment in the karst terrane of the Sinking Creek Basin. Streamflow, nutrient, select pesticide, and suspended-sediment data were collected at seven sampling stations from 2004 through 2006. Concentrations of nitrite plus nitrate ranged from 0.21 to 4.9 milligrams per liter (mg/L) at the seven stations. The median concentration of nitrite plus nitrate for all stations sampled was 1.6 mg/L. Total phosphorus concentrations were greater than 0.1 mg/L, the U.S. Environmental Protection Agency's recommended maximum concentration, in 45 percent of the samples. Concentrations of orthophosphates ranged from less than 0.006 to 0.46 mg/L. Concentrations of nutrients generally were larger during spring and summer months, corresponding to periods of increased fertilizer application on agricultural lands. Concentrations of suspended sediment ranged from 1.0 to 1,490 mg/L at the seven stations. Of the 47 pesticides analyzed, 14 were detected above the adjusted method reporting level of 0.01 micrograms per liter (mug/L). Although these pesticides were detected in water-quality samples, they generally were found at less than part-per-billion concentrations. Atrazine was the only pesticide detected at concentrations greater than U.S. Environmental Protection Agency drinking water standard of 3 mug/L, and the maximum detected concentration was 24.6 mug/L. Loads and yields of nutrients, selected pesticides, and suspended sediment were estimated at two mainstream stations on Sinking Creek, a headwater station (Sinking Creek at Rosetta) and a station at the basin outlet (Sinking Creek near Lodiburg). Mean daily streamflow data were available for the estimation of loads and yields from a stream gage at the basin outlet station; however, only periodic instantaneous flow measurements were available for the headwaters station; mean daily flows at the headwater station were, therefore, estimated using a mathematical record-extension technique known as the Maintenance of Variance-Extension, type 1 (MOVE.1). The estimation of mean daily streamflows introduced a large amount of uncertainty into the loads and yields estimates at the headwater station. Total estimated loads of select (five most commonly detected) pesticides from the Sinking Creek Basin were about 0.01 to 1.2 percent of the estimated application, indicating pesticides possibly are retained within the watershed. Mean annual loads [(in/lb)/yr] for nutrients and suspended sediment were estimated at the two Sinking Creek mainstem sampling stations. The relation between estimated and measured instantaneous loads of nitrite plus nitrate at the Sinking Creek near Lodiburg station indicate a reasonably tight distribution over the range of loads. The model for loads of nitrite plus nitrate at the Sinking Creek at Rosetta station indicates small loads were overestimated and underestimated. Relations between estimated and measured loads of total phosphorus and orthophosphate at both Sinking Creek mainstem stations showed similar patterns to the loads of nitrite plus nitrate at each respective station. The estimated mean annual load of suspended sediment is about 14 times larger at the Sinking Creek near Lodiburg station than at the Sinking Creek near Rosetta station. Estimated yields of nutrients and suspended sediment increased from the headwater to downstream monitoring stations on Sinking Creek. This finding suggests that sources of nutrients and suspended sediment are not evenly distributed throughout the karst terrane of the Sinking Creek Basin. Yields of select pesticides generally were similar from the headwater to downstream monitoring stations. However, the estimated yield of atrazine was about five times higher at the downstream station on Sinking Creek than at the headwater station on Sinking Creek.

9 CFR 317.17 - Interpretation and statement of labeling policy for cured products; special labeling requirements...

Code of Federal Regulations, 2011 CFR

2011-01-01

... labeling policy for cured products; special labeling requirements concerning nitrate and nitrite. 317.17..., sodium phosphate, sodium nitrate, and sodium nitrite or other permitted substances which are added to any... nitrate or nitrite is permitted or required to be added may be prepared without nitrate or nitrite and...

9 CFR 317.17 - Interpretation and statement of labeling policy for cured products; special labeling requirements...

Code of Federal Regulations, 2010 CFR

2010-01-01

... labeling policy for cured products; special labeling requirements concerning nitrate and nitrite. 317.17..., sodium phosphate, sodium nitrate, and sodium nitrite or other permitted substances which are added to any... nitrate or nitrite is permitted or required to be added may be prepared without nitrate or nitrite and...

Spectrophotometric determination of triclosan based on diazotization reaction: response surface optimization using Box-Behnken design.

PubMed

Kaur, Inderpreet; Gaba, Sonal; Kaur, Sukhraj; Kumar, Rajeev; Chawla, Jyoti

2018-05-01

A spectrophotometric method based on diazotization of aniline with triclosan has been developed for the determination of triclosan in water samples. The diazotization process involves two steps: (1) reaction of aniline with sodium nitrite in an acidic medium to form diazonium ion and (2) reaction of diazonium ion with triclosan to form a yellowish-orange azo compound in an alkaline medium. The resulting yellowish-orange product has a maximum absorption at 352 nm which allows the determination of triclosan in aqueous solution in the linear concentration range of 0.1-3.0 μM with R 2 = 0.998. The concentration of hydrochloric acid, sodium nitrite, and aniline was optimized for diazotization reaction to achieve good spectrophotometric determination of triclosan. The optimization of experimental conditions for spectrophotometric determination of triclosan in terms of concentration of sodium nitrite, hydrogen chloride and aniline was also carried out by using Box-Behnken design of response surface methodology and results obtained were in agreement with the experimentally optimized values. The proposed method was then successfully applied for analyses of triclosan content in water samples.

Development of a dual-analyte fluorescent sensor for the determination of bioactive nitrite and selenite in water samples.

PubMed

Martínez-Tomé, M J; Esquembre, R; Mallavia, R; Mateo, C R

2010-01-20

Nitrite and selenium are two bioactive compounds found in the environment which show beneficial effects for health at low levels but have toxic effects at higher doses. Consequently, quantification of both analytes in water samples results of great interest in areas such as biomedicine, food technology and environmental analysis. In a recent paper, we immobilized the inclusion complex formed between 2,3-diaminonaphthalene (DAN) and 2-hydroxypropyl-beta-cyclodextrin (HP-beta-CD) in a sol-gel matrix, in order to prepare a highly sensitive reagentless fluorescence-based sensor for the specific measurement of nitrite. Here we have explored the possibility of using the sol-gel immobilized complex to quantify selenite (Se (IV)), the more toxic form of selenium, as well as to act as a dual-analyte chemical sensor for simultaneous quantification of both nitrite and selenite in aqueous samples. Results show that (a) inclusion of DAN in HP-beta-CD and its subsequent immobilization in a sol-gel matrix do not modify the reactivity of DAN against selenite, (b) the reaction product formed (4,5-benzopiazselenol) remains into the cyclodextrin increasing considerably its fluorescence quantum yield and avoiding, therefore, its extraction into organic solvents, (c) the developed sensor can detect selenite concentrations at submicromolar level with a minimum detection limit of 13 nM, (d) the immobilized system is able to simultaneously quantify nitrite and selenite at submicromolar concentrations in natural water samples with no further sample pre-treatment.

The environmental controls that govern the end product of bacterial nitrate respiration

DOE PAGES

Kraft, Beate; Tegetmeyer, Halina E.; Sharma, Ritin; ...

2014-08-08

In the biogeochemical nitrogen cycle, microbial respiration processes compete for nitrate as an electron acceptor. Denitrification converts nitrate into nitrogenous gas and thus removes fixed nitrogen from the biosphere, whereas ammonification converts nitrate into ammonium, which is directly reusable by primary producers. In this paper, we combined multiple parallel long-term incubations of marine microbial nitrate-respiring communities with isotope labeling and metagenomics to unravel how specific environmental conditions select for either process. Microbial generation time, supply of nitrite relative to nitrate, and the carbon/nitrogen ratio were identified as key environmental controls that determine whether nitrite will be reduced to nitrogenous gasmore » or ammonium. Finally, our results define the microbial ecophysiology of a biogeochemical feedback loop that is key to global change, eutrophication, and wastewater treatment.« less

Selection of Crop Varieties for Efficient Production Using Urea, Ammonia, Nitrite, and Nitrate in Celss

NASA Technical Reports Server (NTRS)

Huffaker, R. C.

1982-01-01

The presence of NO2(-) in the external solution increased the overall efficiency of the mixed N sources by cereal leaves. The NH4(+) in the substrate solution decreased the efficiency of NO3(-) reduction, while NO3(-) in the substrate solution increased the efficiency of NH4(+) assimilation.

Role of blood and vascular smooth muscle in the vasoactivity of nitrite.

PubMed

Liu, Taiming; Schroeder, Hobe J; Barcelo, Lisa; Bragg, Shannon L; Terry, Michael H; Wilson, Sean M; Power, Gordon G; Blood, Arlin B

2014-10-01

Recent evidence from humans and rats indicates that nitrite is a vasodilator under hypoxic conditions by reacting with metal-containing proteins to produce nitric oxide (NO). We tested the hypothesis that near-physiological concentrations of nitrite would produce vasodilation in a hypoxia- and concentration-dependent manner in the hind limb of sheep. Anesthetized sheep were instrumented to measure arterial blood pressure and femoral blood flows continuously in both hind limbs. Nitrite was infused into one femoral artery to raise the nitrite concentration in the femoral vein by 10 to 15-fold while the sheep breathed 50%, 14% or 12% oxygen in inspired air. In contrast to reports in humans and rats, the nitrite infusion had no measurable effect on mean femoral blood flows or vascular conductances, regardless of inspired O2 levels. In vitro experiments showed no significant difference in the release of NO from nitrite in sheep and human red blood cells. Further experiments demonstrated nitrite is converted to NO in rat artery homogenates faster than sheep arteries, and that this source of NO production is attenuated in the presence of a heme oxidizer. Finally, western blots indicate that concentrations of the heme-containing protein cytoglobin, but not myoglobin, are markedly lower in sheep arteries compared with rats. Overall, the results demonstrate that nitrite is not a physiological vasodilator in sheep. This is likely due to a lack of conversion of nitrite to NO within the vascular smooth muscle, perhaps due to deficient amounts of the heme-containing protein cytoglobin. Copyright © 2014 the American Physiological Society.

Low NO Concentration Dependence of Reductive Nitrosylation Reaction of Hemoglobin*

PubMed Central

Tejero, Jesús; Basu, Swati; Helms, Christine; Hogg, Neil; King, S. Bruce; Kim-Shapiro, Daniel B.; Gladwin, Mark T.

2012-01-01

The reductive nitrosylation of ferric (met)hemoglobin is of considerable interest and remains incompletely explained. We have previously observed that at low NO concentrations the reaction with tetrameric hemoglobin occurs with an observed rate constant that is at least 5 times faster than that observed at higher concentrations. This was ascribed to a faster reaction of NO with a methemoglobin-nitrite complex. We now report detailed studies of this reaction of low NO with methemoglobin. Nitric oxide paradoxically reacts with ferric hemoglobin with faster observed rate constants at the lower NO concentration in a manner that is not affected by changes in nitrite concentration, suggesting that it is not a competition between NO and nitrite, as we previously hypothesized. By evaluation of the fast reaction in the presence of allosteric effectors and isolated β- and α-chains of hemoglobin, it appears that NO reacts with a subpopulation of β-subunit ferric hemes whose population is influenced by quaternary state, redox potential, and hemoglobin dimerization. To further characterize the role of nitrite, we developed a system that oxidizes nitrite to nitrate to eliminate nitrite contamination. Removal of nitrite does not alter reaction kinetics, but modulates reaction products, with a decrease in the formation of S-nitrosothiols. These results are consistent with the formation of NO2/N2O3 in the presence of nitrite. The observed fast reductive nitrosylation observed at low NO concentrations may function to preserve NO bioactivity via primary oxidation of NO to form nitrite or in the presence of nitrite to form N2O3 and S-nitrosothiols. PMID:22493289

Evidence that inhibitory factor extracted from bovine retractor penis is nitrite, whose acid-activated derivative is stabilized nitric oxide.

PubMed Central

Martin, W.; Smith, J. A.; Lewis, M. J.; Henderson, A. H.

1988-01-01

1. Unactivated extracts of bovine retractor penis (BRP) contains 3-7 microM nitrite. Acid-activation of these extracts at pH 2 for 10 min followed by neutralization generates the active form of inhibitory factor (IF; assayed by its vasodilator action on rabbit aorta), and is associated with partial loss of nitrite. 2. Increasing the time of acid-activation at pH 2 from 10 to 60 min with intermittent vortex mixing generates greater vasodilator activity and increases nitrite loss. 3. When acid-activated and neutralized extracts are incubated at 37 degrees C or 30 min or boiled for 5 min, vasodilator activity is lost and nitrite content increased. Reactivation of these samples at pH 2 for 10 min followed by neutralization leads to partial recoveries of vasodilator activity with loss in nitrite content. 4. Addition of sodium nitrite to BRP extracts increases acid-activatable vasodilator activity pro rata. 5. Acid-activation of aqueous sodium nitrite solutions results in less loss of nitrite and generation of less vasodilator activity than BRP extracts. Vasodilatation is only transient and is rapidly abolished on neutralization, whereas responses to acid-activated BRP extracts are more prolonged and activity is stable on ice. 6. Bovine aortic endothelial cells yield vasodilator activity that is indistinguishable from that isolated from BRP. It is activated by acid, stable on ice, abolished by boiling or by haemoglobin, and appears to be due to the generation of nitric oxide (NO) from nitrite.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2897219

Role of blood and vascular smooth muscle in the vasoactivity of nitrite

PubMed Central

Liu, Taiming; Schroeder, Hobe J.; Barcelo, Lisa; Bragg, Shannon L.; Terry, Michael H.; Wilson, Sean M.; Power, Gordon G.

2014-01-01

Recent evidence from humans and rats indicates that nitrite is a vasodilator under hypoxic conditions by reacting with metal-containing proteins to produce nitric oxide (NO). We tested the hypothesis that near-physiological concentrations of nitrite would produce vasodilation in a hypoxia- and concentration-dependent manner in the hind limb of sheep. Anesthetized sheep were instrumented to measure arterial blood pressure and femoral blood flows continuously in both hind limbs. Nitrite was infused into one femoral artery to raise the nitrite concentration in the femoral vein by 10 to 15-fold while the sheep breathed 50%, 14% or 12% oxygen in inspired air. In contrast to reports in humans and rats, the nitrite infusion had no measurable effect on mean femoral blood flows or vascular conductances, regardless of inspired O2 levels. In vitro experiments showed no significant difference in the release of NO from nitrite in sheep and human red blood cells. Further experiments demonstrated nitrite is converted to NO in rat artery homogenates faster than sheep arteries, and that this source of NO production is attenuated in the presence of a heme oxidizer. Finally, western blots indicate that concentrations of the heme-containing protein cytoglobin, but not myoglobin, are markedly lower in sheep arteries compared with rats. Overall, the results demonstrate that nitrite is not a physiological vasodilator in sheep. This is likely due to a lack of conversion of nitrite to NO within the vascular smooth muscle, perhaps due to deficient amounts of the heme-containing protein cytoglobin. PMID:25108012

Multiple metabolisms constrain the anaerobic nitrite budget in the Eastern Tropical South Pacific

NASA Astrophysics Data System (ADS)

Babbin, Andrew R.; Peters, Brian D.; Mordy, Calvin W.; Widner, Brittany; Casciotti, Karen L.; Ward, Bess B.

2017-02-01

The Eastern Tropical South Pacific is one of the three major oxygen deficient zones (ODZs) in the global ocean and is responsible for approximately one third of marine water column nitrogen loss. It is the best studied of the ODZs and, like the others, features a broad nitrite maximum across the low oxygen layer. How the microbial processes that produce and consume nitrite in anoxic waters interact to sustain this feature is unknown. Here we used 15N-tracer experiments to disentangle five of the biologically mediated processes that control the nitrite pool, including a high-resolution profile of nitrogen loss rates. Nitrate reduction to nitrite likely depended on organic matter fluxes, but the organic matter did not drive detectable rates of denitrification to N2. However, multiple lines of evidence show that denitrification is important in shaping the biogeochemistry of this ODZ. Significant rates of anaerobic nitrite oxidation at the ODZ boundaries were also measured. Iodate was a potential oxidant that could support part of this nitrite consumption pathway. We additionally observed N2 production from labeled cyanate and postulate that anammox bacteria have the ability to harness cyanate as another form of reduced nitrogen rather than relying solely on ammonification of complex organic matter. The balance of the five anaerobic rates measured—anammox, denitrification, nitrate reduction, nitrite oxidation, and dissimilatory nitrite reduction to ammonium—is sufficient to reproduce broadly the observed nitrite and nitrate profiles in a simple one-dimensional model but requires an additional source of reduced nitrogen to the deeper ODZ to avoid ammonium overconsumption.

Nitrates and Nitrites in the Treatment of Ischemic Cardiac Disease

PubMed Central

Nossaman, Vaughn E.; Nossaman, Bobby D.; Kadowitz, Philip J.

2010-01-01

The organic nitrite, amyl of nitrite, was initially used as a therapeutic agent in the treatment of angina pectoris in 1867, but was replaced over a decade later by the organic nitrate, nitroglycerin (NTG), due to the ease of administration and longer duration of action. The administration of organic nitrate esters, such as NTG, continues to be used in the treatment of angina pectoris and heart failure during the birth of modern pharmacology. The clinical effectiveness is due to vasodilator activity in large veins and arteries through an as yet unidentified method of delivering nitric oxide (NO), or a NO-like compound to vascular smooth muscle cells. The major drawback with NTG administration is the rapid development of tolerance; and with amyl of nitrite, the duration and route of administration. Although amyl of nitrite are no longer used in the treatments of hypertension or ischemic heart disease, the nitrite anion has recently been discovered to possess novel pharmacologic actions such as modulating hypoxic vasodilation and providing cytoprotection in ischemia-reperfusion injury. Although the actions of these two similar chemical classes (nitrites and organic nitrates) have often been considered to be alike, we still do not understand their mechanism of action. However, the recent discovery that the nitrite anion, derived from either sodium nitrite or an intermediate NTG form, may act as a storage form for NO and provides support for investigating the use of these agents in the treatment of ischemic cardiovascular states. We review what is presently known about the use of nitrites and nitrates, the potential uses of these agents, and their mechanisms of action. PMID:20539102

A comparison of organic and inorganic nitrates/nitrites.

PubMed

Omar, Sami A; Artime, Esther; Webb, Andrew J

2012-05-15

Although both organic and inorganic nitrates/nitrites mediate their principal effects via nitric oxide, there are many important differences. Inorganic nitrate and nitrite have simple ionic structures and are produced endogenously and are present in the diet, whereas their organic counterparts are far more complex, and, with the exception of ethyl nitrite, are all medicinally synthesised products. These chemical differences underlie the differences in pharmacokinetic properties allowing for different modalities of administration, particularly of organic nitrates, due to the differences in their bioavailability and metabolic profiles. Whilst the enterosalivary circulation is a key pathway for orally ingested inorganic nitrate, preventing an abrupt effect or toxic levels of nitrite and prolonging the effects, this is not used by organic nitrates. The pharmacodynamic differences are even greater; while organic nitrates have potent acute effects causing vasodilation, inorganic nitrite's effects are more subtle and dependent on certain conditions. However, in chronic use, organic nitrates are considerably limited by the development of tolerance and endothelial dysfunction, whereas inorganic nitrate/nitrite may compensate for diminished endothelial function, and tolerance has not been reported. Also, while inorganic nitrate/nitrite has important cytoprotective effects against ischaemia-reperfusion injury, continuous use of organic nitrates may increase injury. While there are concerns that inorganic nitrate/nitrite may induce carcinogenesis, direct evidence of this in humans is lacking. While organic nitrates may continue to dominate the therapeutic arena, this may well change with the increasing recognition of their limitations, and ongoing discovery of beneficial effects and specific advantages of inorganic nitrate/nitrite. Copyright © 2012 Elsevier Inc. All rights reserved.

Pancreatic cancer and exposure to dietary nitrate and nitrite in the NIH-AARP Diet and Health Study.

PubMed

Aschebrook-Kilfoy, Briseis; Cross, Amanda J; Stolzenberg-Solomon, Rachael Z; Schatzkin, Arthur; Hollenbeck, Albert R; Sinha, Rashmi; Ward, Mary H

2011-08-01

Nitrate and nitrite are precursors of N-nitroso compounds, which induce tumors of the pancreas in animals. The authors evaluated the relation of dietary nitrate and nitrite to pancreatic cancer risk in the NIH-AARP Diet and Health Study. Nitrate and nitrite intakes were assessed at baseline using a 124-item food frequency questionnaire. During approximately 10 years of follow-up between 1995 and 2006, 1,728 incident pancreatic cancer cases were identified. There was no association between total nitrate or nitrite intake and pancreatic cancer in men or women. However, men in the highest quintile of summed nitrate/nitrite intake from processed meat had a nonsignificantly elevated risk of pancreatic cancer (hazard ratio = 1.18, 95% confidence interval: 0.95, 1.47; P-trend = 0.11). The authors observed a stronger increase in risk among men for nitrate/nitrite intake from processed meat at ages 12-13 years (highest quintile vs. lowest: hazard ratio = 1.32, 95% confidence interval: 0.99, 1.76; P-trend = 0.11), though the relation did not achieve statistical significance. The authors found no associations between adult or adolescent nitrate or nitrite intake from processed meats and pancreatic cancer among women. These results provide modest evidence that processed meat sources of dietary nitrate and nitrite may be associated with pancreatic cancer among men and provide no support for the hypothesis in women.

Effect of Sodium Nitrite on Toxin Production by Clostridium botulinum in bacon

PubMed Central

Christiansen, L. N.; Tompkin, R. B.; Shaparis, A. B.; Kueper, T. V.; Johnston, R. W.; Kautter, D. A.; Kolari, O. J.

1974-01-01

Pork bellies were formulated to 0, 30, 60, 120, 170, or 340 μg of nitrite per g of meat and inoculated with Clostridium botulinum via pickle or after processing and slicing. Processed bacon was stored at 7 or 27 C and assayed for nitrite, nitrate, and botulinal toxin at different intervals. Nitrite levels declined during processing and storage. The rate of decrease was more rapid at 27 than at 7 C. Although not added to the system, nitrate was detected in samples during processing and storage at 7 and 27 C. The amount of nitrate found was related to formulated nitrite levels. No toxin was found in samples incubated at 7 C throughout the 84-day test period. At 27 C, via pickle, inoculated samples with low inoculum (210 C. botulinum per g before processing and 52 per g after processing) became toxic if formulated with 120 μg of nitrite per g of meat or less. Toxin was not detected in bacon formulated with 170 or 340 μg of nitrite per g of meat under these same conditions. Toxin was detected at all formulated nitrite levels in bacon inoculated via the pickle with 19,000 C. botulinum per g (4,300 per g after processing) and in samples inoculated after slicing. However, increased levels of formulated nitrite decreased the probability of botulinal toxin formation in bacon inoculated by both methods. PMID:4596753

Effect of sodium nitrite on toxin production by Clostridium botulinum in bacon.

PubMed

Christiansen, L N; Tompkin, R B; Shaparis, A B; Kueper, T V; Johnston, R W; Kautter, D A; Kolari, O J

1974-04-01

Pork bellies were formulated to 0, 30, 60, 120, 170, or 340 mug of nitrite per g of meat and inoculated with Clostridium botulinum via pickle or after processing and slicing. Processed bacon was stored at 7 or 27 C and assayed for nitrite, nitrate, and botulinal toxin at different intervals. Nitrite levels declined during processing and storage. The rate of decrease was more rapid at 27 than at 7 C. Although not added to the system, nitrate was detected in samples during processing and storage at 7 and 27 C. The amount of nitrate found was related to formulated nitrite levels. No toxin was found in samples incubated at 7 C throughout the 84-day test period. At 27 C, via pickle, inoculated samples with low inoculum (210 C. botulinum per g before processing and 52 per g after processing) became toxic if formulated with 120 mug of nitrite per g of meat or less. Toxin was not detected in bacon formulated with 170 or 340 mug of nitrite per g of meat under these same conditions. Toxin was detected at all formulated nitrite levels in bacon inoculated via the pickle with 19,000 C. botulinum per g (4,300 per g after processing) and in samples inoculated after slicing. However, increased levels of formulated nitrite decreased the probability of botulinal toxin formation in bacon inoculated by both methods.

Further studies on the effect of nitrogen dioxide on mast cells: The effect of the metabolite, nitrite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fujimaki, Hidekazu; Ozawa, Masashi; Bissonnette, E.

1993-05-01

To evaluate the relationship between atmospheric nitrogen dioxide exposure and the development of allergic diseases, the effects of nitrite as a chemical product of inhaled nitrogen dioxide on mast cell functions were investigated. We have studied nitride-induced histamine release from two functionally distinct mast cell populations, namely peritoneal mast cells (PMC) and intestinal mucosal mast cells (IMMC) of Nippostrongylus brasiliensis-infected rats. High concentrations of nitrite alone (10, 20, and 50 mM) induced histamine release from IMMC, but not from PMC. Moreover, histamine release from PMC and IMMC stimulated with sensitizing antigen was significantly enhanced by pretreatment with 50 mM nitritemore » or nitrate. No differences in histamine release from nitrite-treated and control PMC were seen below 1 mM. To investigate the effect of nitrite on tumor cell cytotoxic activity, PMC were incubated with various concentrations of nitrite. Pretreatment with 5 and 50 mM nitrite markedly depressed tumor necrosis factor (TNF)-[alpha]-dependent natural cytotoxicity of PMC for the tumor target WEHI-164. Thus, high concentrations of nitrite enhanced mast cell histamine release, but depressed TNF-[alpha]-dependent cytotoxicity. However, low concentrations of nitrite (<1 mM) that would normally be produced by short-term atmospheric exposure to nitrogen dioxide may have no significant effects on mast cell functions. 27 refs., 3 figs., 1 tab.« less

Water-Quality Characterization of Surface Water in the Onondaga Lake Basin, Onondaga County, New York, 2005-08

USGS Publications Warehouse

Coon, William F.; Hayhurst, Brett A.; Kappel, William M.; Eckhardt, David A.V.; Szabo, Carolyn O.

2009-01-01

Water-resources managers in Onondaga County, N.Y., have been faced with the challenge of improving the water-quality of Onondaga Lake. To assist in this endeavor, the U.S. Geological Survey undertook a 3-year basinwide study to assess the water quality of surface water in the Onondaga Lake Basin. The study quantified the relative contributions of nonpoint sources associated with the major land uses in the basin and also focused on known sources (streams with large sediment loads) and presumed sinks (Onondaga Reservoir and Otisco Lake) of sediment and nutrient loads, which previously had not been evaluated. Water samples were collected and analyzed for nutrients and suspended sediment at 26 surface-water sites and 4 springs in the 285-square-mile Onondaga Lake Basin from October 2005 through December 2008. More than 1,060 base-flow, stormflow, snowmelt, spring-water, and quality-assurance samples collected during the study were analyzed for ammonia, nitrite, nitrate-plus-nitrite, ammonia-plus-organic nitrogen, orthophosphate, phosphorus, and suspended sediment. The concentration of total suspended solids was measured in selected samples. Ninety-one additional samples were collected, including 80 samples from 4 county-operated sites, which were analyzed for suspended sediment or total suspended solids, and 8 precipitation and 3 snowpack samples, which were analyzed for nutrients. Specific conductance, salinity, dissolved oxygen, and water temperature were periodically measured in the field. The mean concentrations of selected constituents in base-flow, stormflow, and snowmelt samples were related to the land use or land cover that either dominated the basin or had a substantial effect on the water quality of the basin. Almost 40 percent of the Onondaga Lake Basin is forested, 30 percent is in agricultural uses, and almost 21 percent, including the city of Syracuse, is in developed uses. The data indicated expected relative differences among the land types for concentrations of nitrate, ammonia-plus-organic nitrogen, and orthophosphate. The data departed from the expected relations for concentrations of phosphorus and suspended sediment, and plausible explanations for these departures were posited. Snowmelt concentrations of dissolved constituents generally were greater and those of particulate constituents were less than concentrations of these constituents in storm runoff. Presumably, the snowpack acted as a short-term sink for dissolved constituents that had accumulated from atmospheric deposition, and streambed erosion and resuspension of previously deposited material, rather than land-surface erosion, were the primary sources of particulate constituents in snowmelt flows. Longitudinal assessments documented the changes in the median concentrations of constituents in base flows and event flows (combined stormflow and snowmelt) from upstream to downstream monitoring sites along the two major tributaries to Onondaga Lake - Onondaga Creek and Ninemile Creek. Median base-flow concentrations of ammonia and phosphorus and event concentrations of ammonia increased in the downstream direction in both streams. Whereas median event concentrations of other constituents in Onondaga Creek displayed no consistent trends, concentrations of ammonia-plus-organic nitrogen, orthophosphate, phosphorus, and suspended sediment in Ninemile Creek decreased from upstream to downstream sites. Springs discharging from the Onondaga and Bertie Limestone had measureable effects on water temperatures in the receiving streams and increased salinity and values of specific conductance in base flows. Loads of selected nutrients and suspended sediment transported in three tributaries of Otisco Lake were compared with loads from 1981-83. Loads of ammonia-plus-organic nitrogen and orthophosphate decreased from 1981-83 to 2005-08, but those of nitrate-plus-nitrite, phosphorus, and suspended sediment increased. The largest load increase was for suspende

Nitrite in organ protection

PubMed Central

Rassaf, Tienush; Ferdinandy, Peter; Schulz, Rainer

2014-01-01

In the last decade, the nitrate-nitrite-nitric oxide pathway has emerged to therapeutical importance. Modulation of endogenous nitrate and nitrite levels with the subsequent S-nitros(yl)ation of the downstream signalling cascade open the way for novel cytoprotective strategies. In the following, we summarize the actual literature and give a short overview on the potential of nitrite in organ protection. PMID:23826831

Dietary exposure to benzoates (E210-E213), parabens (E214-E219), nitrites (E249-E250), nitrates (E251-E252), BHA (E320), BHT (E321) and aspartame (E951) in children less than 3 years old in France.

PubMed

Mancini, F R; Paul, D; Gauvreau, J; Volatier, J L; Vin, K; Hulin, M

2015-01-01

This study aimed to estimate the exposure to seven additives (benzoates, parabens, nitrites, nitrates, BHA, BHT and aspartame) in children aged less than 3 years old in France. A conservative approach, combining individual consumption data with maximum permitted levels, was carried out for all the additives. More refined estimates using occurrence data obtained from products' labels (collected by the French Observatory of Food Quality) were conducted for those additives that exceeded the acceptable daily intake (ADI). Information on additives' occurrence was obtained from the food labels. When the ADI was still exceeded, the exposure estimate was further refined using measured concentration data, if available. When using the maximum permitted level (MPL), the ADI was exceeded for benzoates (1.94 mg kg(-1) bw day(-1)), nitrites (0.09 mg kg(-1) bw day(-1)) and BHA (0.39 mg kg(-1) bw day(-1)) in 25%, 54% and 20% of the entire study population respectively. The main food contributors identified with this approach were current foods as these additives are not authorised in specific infant food: vegetable soups and broths for both benzoates and BHA, delicatessen and meat for nitrites. The exposure estimate was significantly reduced when using occurrence data, but in the upper-bound scenario the ADI was still exceeded significantly by the age group 13-36 months for benzoates (2%) and BHA (1%), and by the age group 7-12 months (16%) and 13-36 months (58%) for nitrites. Measured concentration data were available exclusively for nitrites and the results obtained using these data showed that the nitrites' intake was below the ADI for all the population considered in this study. These results suggest that refinement of exposure, based on the assessment of food levels, is needed to estimate the exposure of children to BHA and benzoates for which the risk of exceeding the ADI cannot be excluded when using occurrence data.

Sodium nitrite and sorbic acid effects on Clostridium botulinum spore germination and total microbial growth in chicken frankfurter emulsions during temperature abuse.

PubMed Central

Sofos, J N; Busta, F F; Allen, C E

1979-01-01

Samples of (i) a control or of (ii) sodium nitrite-containing or (iii) sorbic acid-containing, mechanically deboned chicken meat frankfurter-type emulsions inoculated with Clostridium botulinum spores, or a combination of ii and iii, were temperature abuse at 27 degrees C. Spore germination and total microbial growth were followed and examined at specified times and until toxic samples were detected. The spores germinated within 3 days in both control and nitrite (20, 40 and 156 micrograms/g) treatments. Sorbic acid (0.2%) alone or in combination with nitrite (20, 40, and 156 micrograms/g) significantly (P less than 0.05) inhibited spore germinations. No significant germination was recorded until toxic samples were detected. A much longer incubation period was necessary for toxin to be formed in nitrite-sorbic acid combination treatments as contrasted with controls or nitrite and sorbic acid used individually. Total growth was not affected by the presence of nitrite, whereas sorbic acid appeared to depress it. Possible mechanisms explaining the effects of nitrite and sorbic acid on spore germination and growth are postulated. PMID:384904

Impact of nitrite exposure on endocrine, osmoregulatory and cytoprotective functions in the marine teleost Sparus sarba.

PubMed

Deane, Eddie E; Woo, Norman Y S

2007-05-01

The effects of nitrite, at varying concentrations (0, 25 and 50mg/l), on silver sea bream (Sparus sarba), was assessed after 7 days exposure. Nitrite exposure resulted in an elevated renosomatic index in parallel with increased kidney water content. Measurements of serum thyroid hormones demonstrated that levels of thyroxine (T(4)) were decreased upon nitrite exposure whereas triiodothyronine (T(3)) concentrations remained unchanged. Nitrite did not affect serum K and Na levels but did cause an increase in gill sodium pump (Na(+)-K(+)-ATPase) activity. Using immunoassays, it was found that the abundance of the water channel protein, aquaporin 3 (AQP3) was unchanged in gills but decreased in kidneys of sea bream upon nitrite exposure. Immunoassay analysis also demonstrated that the amount of the heat shock protein 70 (HSP70) family were increased in gills, kidney and liver during nitrite exposure whereas amounts of the heat shock protein 90 (HSP90) family increased in kidneys and liver. Taken together, the findings from this study provide new insights into how nitrite affects osmoregulatory, endocrine processes and heat shock protein expression in a marine fish.

Nitric oxide production by cultured human aortic smooth muscle cells: stimulation by fluid flow

NASA Technical Reports Server (NTRS)

Papadaki, M.; Tilton, R. G.; Eskin, S. G.; McIntire, L. V.

1998-01-01

This study demonstrated that exposure of cultured human aortic smooth muscle cells (SMC) to fluid flow resulted in nitric oxide (NO) production, monitored by nitrite and guanosine 3',5'-cyclic monophosphate production. A rapid burst in nitrite production rate was followed by a more gradual increase throughout the period of flow exposure. Neither the initial burst nor the prolonged nitrite production was dependent on the level of shear stress in the range of 1.1-25 dyn/cm2. Repeated exposure to shear stress after a 30-min static period restimulated nitrite production similar to the initial burst. Ca(2+)-calmodulin antagonists blocked the initial burst in nitrite release. An inhibitor of nitric oxide synthase (NOS) blocked nitrite production, indicating that changes in nitrite reflect NO production. Treatment with dexamethasone or cycloheximide had no effect on nitrite production. Monoclonal antibodies directed against the inducible and endothelial NOS isoforms showed no immunoreactivity on Western blots, whereas monoclonal antibodies directed against the neuronal NOS gave specific products. These findings suggest that human aortic SMC express a constitutive neuronal NOS isoform, the enzymatic activity of which is modulated by flow.

Effect of alkalinity on nitrite accumulation in treatment of coal chemical industry wastewater using moving bed biofilm reactor.

PubMed

Hou, Baolin; Han, Hongjun; Jia, Shengyong; Zhuang, Haifeng; Zhao, Qian; Xu, Peng

2014-05-01

Nitrogen removal via nitrite (the nitrite pathway) is more suitable for carbon-limited industrial wastewater. Partial nitrification to nitrite is the primary step to achieve nitrogen removal via nitrite. The effect of alkalinity on nitrite accumulation in a continuous process was investigated by progressively increasing the alkalinity dosage ratio (amount of alkalinity to ammonia ratio, mol/mol). There is a close relationship among alkalinity, pH and the state of matter present in aqueous solution. When alkalinity was insufficient (compared to the theoretical alkalinity amount), ammonia removal efficiency increased first and then decreased at each alkalinity dosage ratio, with an abrupt removal efficiency peak. Generally, ammonia removal efficiency rose with increasing alkalinity dosage ratio. Ammonia removal efficiency reached to 88% from 23% when alkalinity addition was sufficient. Nitrite accumulation could be achieved by inhibiting nitrite oxidizing bacteria (NOB) by free ammonia (FA) in the early period and free nitrous acid in the later period of nitrification when alkalinity was not adequate. Only FA worked to inhibit the activity of NOB when alkalinity addition was sufficient. Copyright © 2014 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

Incubation of curing brines for the production of ready-to-eat, uncured, no-nitrite-or-nitrate-added, ground, cooked and sliced ham.

PubMed

Krause, B L; Sebranek, J G; Rust, R E; Mendonca, A

2011-12-01

Salt concentration, vegetable juice powder (VJP) concentration and temperature were investigated to determine necessary conditions for incubation of curing brines including VJP and a starter culture containing Staphylococcus carnosus prior to production of naturally cured, no-nitrate/nitrite-added meat products. Subsequently, incubated brines were utilized to produce no-nitrate/nitrite-added sliced ham in which quality characteristics and residual nitrite concentrations were measured to determine feasibility of brine incubation for nitrate conversion prior to injection. Two ham treatments (one with VJP and starter culture; one with pre-converted VJP) and a nitrite-added control were used. No differences (P>0.05) were found for color in the VJP treatments. Control sliced ham was redder after 42 days of storage, retaining significantly (P<0.05) greater a* (redness) than either of the VJP treatments. Residual nitrite concentration was greater (P<0.05) in the control hams during the first week of storage. While the nitrite-added control retained greater red color and initially had more residual nitrite than the VJP treatments, the two VJP treatments did not differ from each other. Copyright © 2011 Elsevier Ltd. All rights reserved.

Heterotrophic nitrification and aerobic denitrification by Pseudomonas tolaasii Y-11 without nitrite accumulation during nitrogen conversion.

PubMed

He, Tengxia; Li, Zhenlun; Sun, Quan; Xu, Yi; Ye, Qing

2016-01-01

A hypothermia aerobic nitrite-denitrifying bacterium, Pseudomonas tolaasii strain Y-11, was found to display high removal capabilities for heterotrophic nitrification with ammonium and for aerobic denitrification with nitrate or nitrite nitrogen. When strain Y-11 was cultivated for 4days at 15°C with the initial ammonium, nitrate and nitrite nitrogen concentrations of 209.62, 204.61 and 204.33mg/L (pH 7.2), the ammonium, nitrate and nitrite removal efficiencies were 93.6%, 93.5% and 81.9% without nitrite accumulation, and the corresponding removal rates reached as high as 2.04, 1.99 and 1.74mg/L/h, respectively. Additionally, ammonium was removed mainly during the simultaneous nitrification and denitrification process. All results demonstrate that P. tolaasii strain Y-11 has the particularity to remove ammonium, nitrate and nitrite nitrogen at low temperatures, which guarantees it for future application in winter wastewater treatment. Copyright © 2015 Elsevier Ltd. All rights reserved.

Nitrite-induced anemia in channel catfish, Ictalurus punctatus Rafinesque

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tucker, C.S.; Francis-Floyd, R.; Beleau, M.H.

1989-08-01

Since 1983 numerous cases of anemia have been reported in populations of channel catfish Ictalurus punctatus Rafinesque cultured in the southeastern United States. Environmental nitrite-nitrogen concentrations of 4 mg/L or more occur sporadically in channel catfish culture ponds, and the frequency of occurrence is greatest in the fall and spring. The authors have observed that some cases of anemia in populations of pond-raised channel catfish follow prolonged exposure to high concentrations of environmental nitrite. However, there was no evidence that exposure of channel catfish to environmental nitrite was the cause of the observed anemia. Hemolytic anemia following nitrite exposure hasmore » been described for sea bass Dicentrarchus labrax (L.) and rainbow trout Salmo gairdneri, but not for channel catfish. In the present study the authors show that a variable, but generally mild, anemia develops in channel catfish exposed to nitrite. They also offer a management procedure for preventing the development of anemia during periods of elevated environmental nitrite concentrations.« less

Evaluation of Total Nitrite Pattern Visualization as an Improved Method for Gunshot Residue Detection and its Application to Casework Samples.

PubMed

Berger, Jason; Upton, Colin; Springer, Elyah

2018-04-23

Visualization of nitrite residues is essential in gunshot distance determination. Current protocols for the detection of nitrites include, among other tests, the Modified Griess Test (MGT). This method is limited as nitrite residues are unstable in the environment and limited to partially burned gunpowder. Previous research demonstrated the ability of alkaline hydrolysis to convert nitrates to nitrites, allowing visualization of unburned gunpowder particles using the MGT. This is referred to as Total Nitrite Pattern Visualization (TNV). TNV techniques were modified and a study conducted to streamline the procedure outlined in the literature to maximize the efficacy of the TNV in casework, while reducing the required time from 1 h to 5 min, and enhancing effectiveness on blood-soiled samples. The TNV method was found to provide significant improvement in the ability to detect significant nitrite residues, without sacrificing efficiency, that would allow for the determination of the muzzle-to-target distance. © 2018 American Academy of Forensic Sciences.

Production of cured meat color in nitrite-free Harbin red sausage by Lactobacillus fermentum fermentation.

PubMed

Zhang, Xue; Kong, Baohua; Xiong, Youling L

2007-12-01

Lactobacillus fermentum was substituted for nitrite to produce cured pink color in a Chinese-style sausage. Treatments included inoculations (10(4), 10(6), and 10(8)CFU/g meat) followed by fermentation at 30°C for 8h and then at 4°C for 16h. Control sausage (with sodium nitrite, 60mg/kg meat) was cured at 4°C for 24h without L. fermentum. The UV-Vis spectra of pigment extract from L. fermentum-treated sausage were identical to that of nitrosylmyoglobin (NO-Mb) formed in nitrite-treated control. The NO-Mb concentration and the colorimetric a(∗) value of sausage treated with 10(8)CFU/g meat of L. fermentum essentially replicated those in nitrite-cured meat. Free amino acid content in sausage treated with L. fermentum was greater and the pH slightly lower compared with the nitrite-cured control sample. This study showed that L. fermentum has the potential to substitute for nitrite in the sausage production.

Determination of berberine in pharmaceutical preparations using acidic hydrogen peroxide-nitrite chemiluminescence system.

PubMed

Liang, Yao-Dong; Yu, Chun-Xia

2013-03-01

A stronger chemiluminescence (CL) was observed when hydrogen peroxide was mixed with nitrite and berberine in sulfuric acid solution. The stronger CL originated from peroxidation of berberine by peroxynitrous acid that was synthesized online by the mixing of acidic hydrogen peroxide solution with nitrite solution in a flow system. The emitting species was excited state oxyberberine, a peroxidized product of berberine. Based on the stronger CL, a flow injection CL method for the determination of berberine was proposed. Under optimum experimental conditions, the stronger CL intensity was linearly related to the concentration of berberine over the range of 2.0 × 10(-7) -2.0 × 10(-5) mol L(-1) . The limit of detection (s/n = 3) was 6.2 × 10(-8) mol L(-1) . The proposed method has been evaluated by analyzing berberine in pharmaceutical preparations. Copyright © 2011 John Wiley & Sons, Ltd.

Influence of Edwardsiella ictaluri Septicemia on nitrite-induced methemoglobinemia in channel catfish (Ictalurus punctatus)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tucker, C.S.; MacMillan, J.R.; Schwedler, T.E.

1984-06-01

In a previous report, the authors showed that lack of acclimation to nitrite can result in abnormally high levels of methemoglobin in nitrite-exposed channel catfish. They also observed abnormal methemoglobin levels in fish when concurrent bacteremias are present. Enteric Septicemia of Catfish is an acute bacterial disease caused by Edwardsiella ictaluri. Nitrite-induced methemoglobinemia and Enteric Septicemia of Catfish are both economically important diseases of commercially cultured channel catfish. In the present study, the authors investigated the influence of acute infection with E. ictaluri on the level of methemoblobin in nitrite-exposed channel catfish fingerlings.

Nitrous oxide-forming codenitrification catalyzed by cytochrome P450nor.

PubMed

Su, Fei; Takaya, Naoki; Shoun, Hirofumi

2004-02-01

Intact cells of the denitrifying fungus Fusarium oxysporum were previously shown to catalyze codenitrification to form a hybrid nitrous oxide (N2O) species from nitrite and other nitrogen compounds such as azide and ammonia. Here we show that cytochrome P450nor can catalyze the codenitrification reaction to form N2O from nitric oxide (NO) but not nitrite, and azide or ammonia. The results show that the direct substrate of the codenitrification by intact cells should not be nitrite but NO, which is formed from nitrite by the reaction of a dissimilatory nitrite reductase.

Solubilization and Resolution of the Membrane-Bound Nitrite Reductase from Paracoccus Halodenitrificans into Nitrite and Nitric Oxide Reductases

NASA Technical Reports Server (NTRS)

Grant, Michael A.; Cronin, Sonja E.; Hochstein, Lawrence I.

1984-01-01

Membranes prepared from Paracoccus halodenitrificans reduced nitrite or nitric oxide to nitrous oxide. Extraction of these membranes with the detergent CHAPSO [3-(3-Chlolamidoporopyldimethylammonio)-1-(2- hydroxy-1-propanesulfonate)], followed by ammonium sulfate fractionation of the solubilized proteins, resulted in the separation of nitrite and nitric oxide reductase activities. The fraction containing nitrite reductase activity spectrally resembled a cd-type cytochrome. Several cytochromes were detected in the nitric oxide reductase fraction. Which, if any, of these cytochromes is associated with the reduction of nitric oxide is not clear at this time.

Simultaneous GC-ECNICI-MS measurement of nitrite, nitrate and creatinine in human urine and plasma in clinical settings.

PubMed

Hanff, Erik; Lützow, Moritz; Kayacelebi, Arslan Arinc; Finkel, Armin; Maassen, Mirja; Yanchev, Georgi Radoslavov; Haghikia, Arash; Bavendiek, Udo; Buck, Anna; Lücke, Thomas; Maassen, Norbert; Tsikas, Dimitrios

2017-03-15

Creatinine in urine is a useful biochemical parameter to correct the urinary excretion rate of endogenous and exogenous substances. Nitrite (ONO - ) and nitrate (ONO 2 - ) are metabolites of nitric oxide (NO), a signalling molecule with multiple biological functions. Under certain and standardized conditions, the concentration of nitrate in the urine is a suitable measure of whole body NO synthesis. The urinary nitrate-to-nitrite molar ratio (U NOx R) may indicate nitrite-dependent renal carbonic anhydrase (CA) activity. In clinical studies, urine is commonly collected by spontaneous micturition. In those cases the nitrate and nitrite excretion must be corrected for creatinine excretion. Pentafluorobenzyl (PFB) bromide (PFB-Br) is a useful derivatization reagent of numerous inorganic and organic compounds, including urinary nitrite, nitrate and creatinine, for highly sensitive and specific quantitation by GC-MS. Here, we report on the simultaneous PFB-Br derivatization (60min, 50°C) of ONO - , O 15 NO - , ONO 2 - , O 15 NO 2 - , creatinine (d o -Crea) and [methylo- 2 H 3 ]creatinine (d 3 -Crea) in acetonic dilutions of native human urine and plasma samples (4:1, v/v) and their simultaneous quantification by GC-MS as PFBNO 2 , PFB 15 NO 2 , PFBONO 2 , PFBO 15 NO 2 , d o -Crea-PFB and d 3 -Crea-PFB, respectively. Electron capture negative-ion chemical ionization (ECNICI) of these derivatives generates anions due to [M-PFB] - , i.e., the starting analytes. Quantification is performed by selected-ion monitoring (SIM) of m/z 46 (ONO - ), m/z 47 (O 15 NO - ), m/z 62 (ONO 2 - ), m/z 63 (O 15 NO 2 - ), m/z 112 (d o -Crea), and m/z 115 (d 3 -Crea). Retention times were 2.97min for PFB-ONO 2 /PFB-O 15 NO 2 , 3.1min for PFB-NO 2 /PFB- 15 NO 2 , and 6.7min for d o -Crea-PFB/d 3 -Crea-PFB. We used this method to investigate the effects of long-term oral NaNO 3 or NaCl (serving as placebo) supplementation (each 0.1mmol/kg body weight per day for 3 weeks) on creatinine excretion and U NOx R in 17 healthy young men. Compared to NaCl (n=8), NaNO 3 (n=9) supplementation increased U NOx R (1709±355 vs. 369±77, P<0.05). Creatinine excretion did not differ between the groups (6.67±1.34mM vs. 5.72±1.27mM, P=0.57). The method is also applicable to human plasma. In 78 adults patients newly diagnosed for cerebrovascular disease (CVD), there was a close correlation (r=0.9833) between the creatinine concentrations measured in plasma by GC-ECNICI-MS and those measured in serum by an enzymatic assay. Creatinine-corrected plasma nitrate and nitrite concentrations (P=0.035 and P=0.004, respectively) but not their concentrations (P=0.68 and P=0.40, respectively) differ between male (n=54) and female (n=24) CVD patients. No such differences were found between preterm newborn boys (n=25) and girls (n=22). Like in urine, circulating creatinine may be useful to correct for gender-specific differences in plasma nitrite and nitrate in adults. Chronic NaNO 3 supplementation to healthy young men does not affect renal CA-dependent nitrite excretion or creatinine synthesis and excretion. Copyright © 2016 Elsevier B.V. All rights reserved.

Hemin-Graphene Derivatives with Increased Peroxidase Activities Restrain Protein Tyrosine Nitration.

PubMed

Xu, Huan; Yang, Zhen; Li, Hailing; Gao, Zhonghong

2017-12-14

Protein tyrosine nitration is implicated in the occurrence and progression of pathological conditions involving free radical reactions. It is well recognized that hemin can catalyze protein tyrosine nitration in the presence of nitrite and hydrogen peroxide. Generally, the catalytic efficiency is positively correlated to its peroxidase activity. In this study, however, it is found that the efficiency of hemin in catalyzing protein tyrosine nitration is largely suppressed after functionalization with graphene derivatives, even though its peroxidase-like activity is more than quadrupled. Further studies show that the oxidation of tyrosine is still observed for these composites; dityrosine formation, however, is greatly inhibited. Furthermore, these composites also exhibit strong effects on the oxidation of nitrite into nitrate. Therefore, we propose a mechanism in which hemin-graphene derivatives facilitate the oxidation of tyrosine and nitrite to produce tyrosyl radicals and nitrogen dioxide radicals in the presence of hydrogen peroxide, but graphene interlayers serve as barriers that hinder radical-radical coupling reactions; consequently, protein tyrosine nitration is restrained. This property of hemin-graphene derivatives, by which they catalyze substrate oxidation but suppress radical-radical coupling reactions, shows their great potential in selective oxidation procedures for byproduct removal. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ethyl nitrite is produced in the human stomach from dietary nitrate and ethanol, releasing nitric oxide at physiological pH: potential impact on gastric motility.

PubMed

Rocha, Bárbara S; Gago, Bruno; Barbosa, Rui M; Cavaleiro, Carlos; Laranjinha, João

2015-05-01

Nitric oxide ((∙)NO), a ubiquitous molecule involved in a plethora of signaling pathways, is produced from dietary nitrate in the gut through the so-called nitrate-nitrite-NO pathway. In the stomach, nitrite derived from dietary nitrate triggers a network of chemical reactions targeting endogenous and exogenous biomolecules, thereby producing new compounds with physiological activity. The aim of this study was to ascertain whether compounds with physiological relevance are produced in the stomach upon consumption of nitrate- and ethanol-rich foods. Human volunteers consumed a serving of lettuce (source of nitrate) and alcoholic beverages (source of ethanol). After 15 min, samples of the gastric headspace were collected and ethyl nitrite was identified by GC-MS. Wistar rats were used to study the impact of ethyl nitrite on gastric smooth muscle relaxation at physiological pH. Nitrogen oxides, produced from nitrite in the stomach, induce nitrosation of ethanol from alcoholic beverages in the human stomach yielding ethyl nitrite. Ethyl nitrite, a potent vasodilator, is produced in vivo upon the consumption of lettuce with either red wine or whisky. Moreover, at physiological pH, ethyl nitrite induces gastric smooth muscle relaxation through a cGMP-dependent pathway. Overall, these results suggest that ethyl nitrite is produced in the gastric lumen and releases (∙)NO at physiological pH, which ultimately may have an impact on gastric motility. Systemic effects may also be expected if ethyl nitrite diffuses through the gastric mucosa reaching blood vessels, therefore operating as a (∙)NO carrier throughout the body. These data pinpoint posttranslational modifications as an underappreciated mechanism for the production of novel molecules with physiological impact locally in the gut and highlight the notion that diet may fuel compounds with the potential to modulate gastrointestinal welfare. Copyright © 2015 Elsevier Inc. All rights reserved.

Effect of sodium nitrite and sodium nitrate on botulinal toxin production and nitrosamine formation in wieners.

PubMed

Hustad, G O; Cerveny, J G; Trenk, H; Deibel, R H; Kautter, D A; Fazio, T; Johnston, R W; Kolari, O E

1973-07-01

Wieners were formulated and processed approximating commercial conditions as closely as possible. Twenty-four batches of product were made with the addition of six levels of sodium nitrite (0, 50, 100, 150, 200, and 300 mug/g), four levels of sodium nitrate (0, 50, 150, and 450 mug/g), and two levels of Clostridium botulinum (0 and 620 spores/g). After formulation, processing, and vacuum packaging, portions of each batch were incubated at 27 C or held for 21 days at 7 C followed by incubation at 27 C for 56 days. The latter storage condition approximated distribution of product through commercial channels and potential temperature abuse at the consumer level. Samples were analyzed for botulinal toxin, nitrite, and nitrate levels after 3, 7, 14, 21, 28, and 56 days of incubation. When nitrite was not added, toxic samples were detected after 14 days of incubation at 27 C. At the lowest level of nitrite added (50 mug/g), no toxic samples were observed until 56 days of incubation. Higher levels of nitrite completely inhibited toxin production throughout the incubation period. Nine uninoculated samples, representing various levels and combinations of nitrite and nitrate, were evaluated organoleptically. The flavor quality of wieners made with nitrite was judged significantly higher (P = 0.05) than of wieners made without nitrite. The nine samples were negative for 14 volatile nitrosamines at a sensitivity level of 10 ng/g. The results indicated that nitrite effectively inhibited botulinal toxin formation at commercially employed levels in wieners and that detectable quantities of nitrosamines were not produced during preparation and processing of the product for consumption.

Effect of Sodium Nitrite and Sodium Nitrate on Botulinal Toxin Production and Nitrosamine Formation in Wieners

PubMed Central

Hustad, Gerald O.; Cerveny, John G.; Trenk, Hugh; Deibel, Robert H.; Kautter, Donald A.; Fazio, Thomas; Johnston, Ralph W.; Kolari, Olaf E.

1973-01-01

Wieners were formulated and processed approximating commercial conditions as closely as possible. Twenty-four batches of product were made with the addition of six levels of sodium nitrite (0, 50, 100, 150, 200, and 300 μg/g), four levels of sodium nitrate (0, 50, 150, and 450 μg/g), and two levels of Clostridium botulinum (0 and 620 spores/g). After formulation, processing, and vacuum packaging, portions of each batch were incubated at 27 C or held for 21 days at 7 C followed by incubation at 27 C for 56 days. The latter storage condition approximated distribution of product through commercial channels and potential temperature abuse at the consumer level. Samples were analyzed for botulinal toxin, nitrite, and nitrate levels after 3, 7, 14, 21, 28, and 56 days of incubation. When nitrite was not added, toxic samples were detected after 14 days of incubation at 27 C. At the lowest level of nitrite added (50 μg/g), no toxic samples were observed until 56 days of incubation. Higher levels of nitrite completely inhibited toxin production throughout the incubation period. Nine uninoculated samples, representing various levels and combinations of nitrite and nitrate, were evaluated organoleptically. The flavor quality of wieners made with nitrite was judged significantly higher (P = 0.05) than of wieners made without nitrite. The nine samples were negative for 14 volatile nitrosamines at a sensitivity level of 10 ng/g. The results indicated that nitrite effectively inhibited botulinal toxin formation at commercially employed levels in wieners and that detectable quantities of nitrosamines were not produced during preparation and processing of the product for consumption. PMID:4580194

Nitrite activates protein kinase A in normoxia to mediate mitochondrial fusion and tolerance to ischaemia/reperfusion

PubMed Central

Pride, Christelle Kamga; Mo, Li; Quesnelle, Kelly; Dagda, Ruben K.; Murillo, Daniel; Geary, Lisa; Corey, Catherine; Portella, Rafael; Zharikov, Sergey; St Croix, Claudette; Maniar, Salony; Chu, Charleen T.; K. H. Khoo, Nicholas; Shiva, Sruti

2014-01-01

Aims Nitrite (NO2–), a dietary constituent and nitric oxide (NO) oxidation product, mediates cardioprotection after ischaemia/reperfusion (I/R) in a number of animal models when administered during ischaemia or as a pre-conditioning agent hours to days prior to the ischaemic episode. When present during ischaemia, the reduction of nitrite to bioactive NO by deoxygenated haem proteins accounts for its protective effects. However, the mechanism of nitrite-induced pre-conditioning, a normoxic response which does not appear to require reduction of nitrite to NO, remains unexplored. Methods and results Using a model of hypoxia/reoxygenation (H/R) in cultured rat H9c2 cardiomyocytes, we demonstrate that a transient (30 min) normoxic nitrite treatment significantly attenuates cell death after a hypoxic episode initiated 1 h later. Mechanistically, this protection depends on the activation of protein kinase A, which phosphorylates and inhibits dynamin-related protein 1, the predominant regulator of mitochondrial fission. This results morphologically, in the promotion of mitochondrial fusion and functionally in the augmentation of mitochondrial membrane potential and superoxide production. We identify AMP kinase (AMPK) as a downstream target of the mitochondrial reactive oxygen species (ROS) generated and show that its oxidation and subsequent phosphorylation are essential for cytoprotection, as scavenging of ROS prevents AMPK activation and inhibits nitrite-mediated protection after H/R. The protein kinase A-dependent protection mediated by nitrite is reproduced in an intact isolated rat heart model of I/R. Conclusions These data are the first to demonstrate nitrite-dependent normoxic modulation of both mitochondrial morphology and function and reveal a novel signalling pathway responsible for nitrite-mediated cardioprotection. PMID:24081164

Simultaneous nitrification and denitrification with different mixed nitrogen loads by a hypothermia aerobic bacterium.

PubMed

He, Tengxia; Li, Zhenlun; Xie, Deti; Sun, Quan; Xu, Yi; Ye, Qing; Ni, Jiupai

2018-04-01

Microorganism with simultaneous nitrification and denitrification ability plays a significant role in nitrogen removal process, especially in the eutrophic waters with excessive nitrogen loads. The nitrogen removal capacity of microorganism may suffer from low temperature or nitrite nitrogen source. In this study, a hypothermia aerobic nitrite-denitrifying bacterium, Pseudomonas tolaasii strain Y-11, was selected to determine the simultaneous nitrification and denitrification ability with mixed nitrogen source at 15 °C. The sole nitrogen removal efficiencies of strain Y-11 in simulated wastewater were obtained. After 24 h of incubation at 15 °C, the ammonium nitrogen fell below the detection limit from an initial value of 10.99 mg/L. Approximately 88.0 ± 0.33% of nitrate nitrogen was removed with the initial concentration of 11.78 mg/L and the nitrite nitrogen was not detected with the initial concentration of 10.75 mg/L after 48 h of incubation at 15 °C. Additionally, the simultaneous nitrification and denitrification nitrogen removal ability of P. tolaasii strain Y-11 was evaluated using low concentration of mixed NH 4 + -N and NO 3 - -N/NO 2 - -N (about 5 mg/L-N each) and high concentration of mixed NH 4 + -N and NO 3 - -N/NO 2 - -N (about 100 mg/L-N each). There was no nitrite nitrogen accumulation at the time of evaluation. The results demonstrated that P. tolaasii strain Y-11 had higher simultaneous nitrification and denitrification capacity with low concentration of mixed inorganic nitrogen sources and may be applied in low temperature wastewater treatment.

Pancreatic Cancer and Exposure to Dietary Nitrate and Nitrite in the NIH-AARP Diet and Health Study

PubMed Central

Aschebrook-Kilfoy, Briseis; Cross, Amanda J.; Stolzenberg-Solomon, Rachael Z.; Schatzkin, Arthur; Hollenbeck, Albert R.; Sinha, Rashmi; Ward, Mary H.

2011-01-01

Nitrate and nitrite are precursors of N-nitroso compounds, which induce tumors of the pancreas in animals. The authors evaluated the relation of dietary nitrate and nitrite to pancreatic cancer risk in the NIH-AARP Diet and Health Study. Nitrate and nitrite intakes were assessed at baseline using a 124-item food frequency questionnaire. During approximately 10 years of follow-up between 1995 and 2006, 1,728 incident pancreatic cancer cases were identified. There was no association between total nitrate or nitrite intake and pancreatic cancer in men or women. However, men in the highest quintile of summed nitrate/nitrite intake from processed meat had a nonsignificantly elevated risk of pancreatic cancer (hazard ratio = 1.18, 95% confidence interval: 0.95, 1.47; P-trend = 0.11). The authors observed a stronger increase in risk among men for nitrate/nitrite intake from processed meat at ages 12–13 years (highest quintile vs. lowest: hazard ratio = 1.32, 95% confidence interval: 0.99, 1.76; P-trend = 0.11), though the relation did not achieve statistical significance. The authors found no associations between adult or adolescent nitrate or nitrite intake from processed meats and pancreatic cancer among women. These results provide modest evidence that processed meat sources of dietary nitrate and nitrite may be associated with pancreatic cancer among men and provide no support for the hypothesis in women. PMID:21685410

Inorganic nitrite supplementation for healthy arterial aging

PubMed Central

DeVan, Allison E.; Fleenor, Bradley S.; Seals, Douglas R.

2014-01-01

Aging is the major risk factor for cardiovascular diseases (CVD). This is attributable primarily to adverse changes in arteries, notably, increases in large elastic artery stiffness and endothelial dysfunction mediated by inadequate concentrations of the vascular-protective molecule, nitric oxide (NO), and higher levels of oxidative stress and inflammation. Inorganic nitrite is a promising precursor molecule for augmenting circulating and tissue NO bioavailability because it requires only a one-step reduction to NO. Nitrite also acts as an independent signaling molecule, exerting many of the effects previously attributed to NO. Results of recent studies indicate that nitrite may be effective in the treatment of vascular aging. In old mice, short-term oral sodium nitrite supplementation reduces aortic pulse wave velocity, the gold-standard measure of large elastic artery stiffness, and ameliorates endothelial dysfunction, as indicated by normalization of NO-mediated endothelium-dependent dilation. These improvements in age-related vascular dysfunction with nitrite are mediated by reductions in oxidative stress and inflammation, and may be linked to increases in mitochondrial biogenesis and health. Increasing nitrite levels via dietary intake of nitrate appears to have similarly beneficial effects in many of the same physiological and clinical settings. Several clinical trials are being performed to determine the broad therapeutic potential of increasing nitrite bioavailability on human health and disease, including studies related to vascular aging. In summary, inorganic nitrite, as well as dietary nitrate supplementation, represents a promising therapy for treatment of arterial aging and prevention of age-associated CVD in humans. PMID:24408999

Erratum to ;Coastal water column ammonium and nitrite oxidation are decoupled in summer;

NASA Astrophysics Data System (ADS)

Heiss, Elise M.; Fulweiler, Robinson W.

2017-07-01

Water column nitrification is a key process in the nitrogen cycle as it links reduced and oxidized forms of nitrogen and also provides the substrate (nitrate) needed for reactive nitrogen removal by denitrification. We measured potential water column ammonium and nitrite oxidation rates at four sites along an estuary to continental shelf gradient over two summers. In most cases, nitrite oxidation rates outpaced ammonium oxidation rates. Overall, ammonium and nitrite oxidation rates were higher outside of the estuary, and this trend was primarily driven by higher oxidation rates in deeper waters. Additionally, both ammonium and nitrite oxidation rates were impacted by different in situ variables. Ammonium oxidation rates throughout the water column as a whole were most positively correlated to depth and salinity and negatively correlated to dissolved oxygen, light, and temperature. In contrast, nitrite oxidation rates throughout the water column were negatively correlated with temperature, light and pH. Multivariate regression analysis revealed that surface (<20 m) ammonium oxidation rates were most strongly predicted by substrate (NH4+), salinity, and light, while deep (>20 m) rates were regulated by temperature, light, and [H+] (i.e. pH). In addition, surface (<20 m) nitrite oxidation rates were best explained by [H+] alone, while [H+], temperature, and dissolved oxygen all played a role in predicting deep (>20 m) nitrite oxidation rates. These results support the growing body of evidence that ammonium oxidation and nitrite oxidation are not always coupled, should be measured separately, and are influenced by different environmental conditions.

Supporting palladium metal on gold nanoparticles improves its catalysis for nitrite reduction

NASA Astrophysics Data System (ADS)

Qian, Huifeng; Zhao, Zhun; Velazquez, Juan C.; Pretzer, Lori A.; Heck, Kimberly N.; Wong, Michael S.

2013-12-01

Nitrate (NO3-) and nitrite (NO2-) anions are often found in groundwater and surface water as contaminants globally, especially in agricultural areas due to nitrate-rich fertilizer use. One popular approach to studying the removal of nitrite/nitrate from water has been their degradation to dinitrogen via Pd-based reduction catalysis. However, little progress has been made towards understanding how the catalyst structure can improve activity. Focusing on the catalytic reduction of nitrite in this study, we report that Au NPs supporting Pd metal ("Pd-on-Au NPs") show catalytic activity that varies with volcano-shape dependence on Pd surface coverage. At room temperature, in CO2-buffered water, and under H2 headspace, the NPs were maximally active at a Pd surface coverage of 80%, with a first-order rate constant (kcat = 576 L gPd-1 min-1) that was 15x and 7.5x higher than monometallic Pd NPs (~4 nm; 40 L gPd-1 min-1) and Pd/Al2O3 (1 wt% Pd; 76 L gPd-1 min-1), respectively. Accounting only for surface Pd atoms, these NPs (576 L gsurface-Pd-1 min-1) were 3.6x and 1.6x higher than monometallic Pd NPs (160 L gsurface-Pd-1 min-1) and Pd/Al2O3 (361 L gsurface-Pd-1 min-1). These NPs retained ~98% of catalytic activity at a chloride concentration of 1 mM, whereas Pd/Al2O3 lost ~50%. The Pd-on-Au nanostructure is a promising approach to improve the catalytic reduction process for nitrite and, with further development, also for nitrate anions.Nitrate (NO3-) and nitrite (NO2-) anions are often found in groundwater and surface water as contaminants globally, especially in agricultural areas due to nitrate-rich fertilizer use. One popular approach to studying the removal of nitrite/nitrate from water has been their degradation to dinitrogen via Pd-based reduction catalysis. However, little progress has been made towards understanding how the catalyst structure can improve activity. Focusing on the catalytic reduction of nitrite in this study, we report that Au NPs supporting Pd metal ("Pd-on-Au NPs") show catalytic activity that varies with volcano-shape dependence on Pd surface coverage. At room temperature, in CO2-buffered water, and under H2 headspace, the NPs were maximally active at a Pd surface coverage of 80%, with a first-order rate constant (kcat = 576 L gPd-1 min-1) that was 15x and 7.5x higher than monometallic Pd NPs (~4 nm; 40 L gPd-1 min-1) and Pd/Al2O3 (1 wt% Pd; 76 L gPd-1 min-1), respectively. Accounting only for surface Pd atoms, these NPs (576 L gsurface-Pd-1 min-1) were 3.6x and 1.6x higher than monometallic Pd NPs (160 L gsurface-Pd-1 min-1) and Pd/Al2O3 (361 L gsurface-Pd-1 min-1). These NPs retained ~98% of catalytic activity at a chloride concentration of 1 mM, whereas Pd/Al2O3 lost ~50%. The Pd-on-Au nanostructure is a promising approach to improve the catalytic reduction process for nitrite and, with further development, also for nitrate anions. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr04540d

Enhancing nitrite inhibition of Clostridium botulinum with isoascorbate in perishable canned cured meat.

PubMed Central

Tompkin, R B; Christiansen, L N; Shaparis, A B

1978-01-01

Addition of sodium isoascorbate to the formulation for perishable canned comminuted cured meat markedly enhanced the efficacy of nitrite against Clostridium botulinum. This effect was reproducible through a series of three tests. In one test it was found that the initial addition of 50 microgram of sodium nitrite per g plus isoascorbate was as effective as 156 microgram of sodium nitrite per g alone. PMID:341810

Short-term effects of a high nitrate diet on nitrate metabolism in healthy individuals.

PubMed

Bondonno, Catherine P; Liu, Alex H; Croft, Kevin D; Ward, Natalie C; Puddey, Ian B; Woodman, Richard J; Hodgson, Jonathan M

2015-03-12

Dietary nitrate, through the enterosalivary nitrate-nitrite-NO pathway, can improve blood pressure and arterial stiffness. How long systemic nitrate and nitrite remain elevated following cessation of high nitrate intake is unknown. In 19 healthy men and women, the time for salivary and plasma nitrate and nitrite to return to baseline after 7 days increased nitrate intake from green leafy vegetables was determined. Salivary and plasma nitrate and nitrite was measured at baseline [D0], end of high nitrate diet [D7], day 9 [+2D], day 14 [+7D] and day 21 [+14D]. Urinary nitrite and nitrate was assessed at D7 and +14D. Increased dietary nitrate for 7 days resulted in a more than fourfold increase in saliva and plasma nitrate and nitrite (p < 0.001) measured at [D7]. At [+2D] plasma nitrite and nitrate had returned to baseline while saliva nitrate and nitrite were more than 1.5 times higher than at baseline levels. By [+7D] all metabolites had returned to baseline levels. The pattern of response was similar between men and women. Urinary nitrate and nitrate was sevenfold higher at D7 compared to +14D. These results suggest that daily ingestion of nitrate may be required to maintain the physiological changes associated with high nitrate intake.

A novel, kinetically stable, catalytically active, all-ferric, nitrite-bound complex of Paracoccus pantotrophus cytochrome cd1.

PubMed Central

Allen, James W A; Higham, Christopher W; Zajicek, Richard S; Watmough, Nicholas J; Ferguson, Stuart J

2002-01-01

The oxidized form of Paracoccus pantotrophus cytochrome cd(1) nitrite reductase, as isolated, has bis-histidinyl co-ordination of the c haem and His/Tyr co-ordination of the d(1) haem. On reduction, the haem co-ordinations change to His/Met and His/vacant respectively. If the latter form of the enzyme is reoxidized, a conformer is generated in which the ferric c haem is His/Met co-ordinated; this can revert to the 'as isolated' state of the enzyme over approx. 20 min at room temperature. However, addition of nitrite to the enzyme after a cycle of reduction and reoxidation produces a kinetically stable, all-ferric complex with nitrite bound to the d(1) haem and His/Met co-ordination of the c haem. This complex is catalytically active with the physiological electron donor protein pseudoazurin. The effective dissociation constant for nitrite is 2 mM. Evidence is presented that d(1) haem is optimized to bind nitrite, as opposed to other anions that are commonly good ligands to ferric haem. The all-ferric nitrite bound state of the enzyme could not be generated stoichiometrically by mixing nitrite with the 'as isolated' conformer of cytochrome cd(1) without redox cycling. PMID:12086580

Increased nitrite reductase activity of fetal versus adult ovine hemoglobin

PubMed Central

Blood, Arlin B.; Tiso, Mauro; Verma, Shilpa T.; Lo, Jennifer; Joshi, Mahesh S.; Azarov, Ivan; Longo, Lawrence D.; Gladwin, Mark T.; Kim-Shapiro, Daniel B.; Power, Gordon G.

2009-01-01

Growing evidence indicates that nitrite, NO2−, serves as a circulating reservoir of nitric oxide (NO) bioactivity that is activated during physiological and pathological hypoxia. One of the intravascular mechanisms for nitrite conversion to NO is a chemical nitrite reductase activity of deoxyhemoglobin. The rate of NO production from this reaction is increased when hemoglobin is in the R conformation. Because the mammalian fetus exists in a low-oxygen environment compared with the adult and is exposed to episodes of severe ischemia during the normal birthing process, and because fetal hemoglobin assumes the R conformation more readily than adult hemoglobin, we hypothesized that nitrite reduction to NO may be enhanced in the fetal circulation. We found that the reaction was faster for fetal than maternal hemoglobin or blood and that the reactions were fastest at 50–80% oxygen saturation, consistent with an R-state catalysis that is predominant for fetal hemoglobin. Nitrite concentrations were similar in blood taken from chronically instrumented normoxic ewes and their fetuses but were elevated in response to chronic hypoxia. The findings suggest an augmented nitrite reductase activity of fetal hemoglobin and that the production of nitrite may participate in the regulation of vascular NO homeostasis in the fetus. PMID:19028797

Music stimuli lead to increased levels of nitrite in unstimulated mixed saliva.

PubMed

Jin, Luyuan; Zhang, Mengbi; Xu, Junji; Xia, Dengsheng; Zhang, Chunmei; Wang, Jingsong; Wang, Songlin

2018-06-15

Concentration of salivary nitrate is approximately 10-fold to that of serum. Many circumstances such as acute stress could promote salivary nitrate secretion and nitrite formation. However, whether other conditions can also be used as regulators of salivary nitrate/nitrite has not yet been explored. The present study was designed to determine the influence of exposure to different music on the salivary flow rate and nitrate secretion and nitrite formation. Twenty-four undergraduate students (12 females and 12 males) were exposed to silence, rock music, classical music or white noise respectively on four consecutive mornings. The unstimulated salivary flow rate and stimulated salivary flow rate were measured. Salivary ionic (Na + , Ca 2+ Cl - , and PO 4 3- ) content and nitrate/nitrite levels were detected. The unstimulated salivary flow rate was significantly increased after classical music exposure compared to that after silence. Salivary nitrite levels were significantly higher upon classical music and white noise stimulation than those under silence in females. However, males were more sensitive only to white noise with regard to the nitrite increase. In conclusion, this study demonstrated that classical music stimulation promotes salivary nitrite formation and an increase in saliva volume was observed. These observations may play an important role in regulating oral function.

An investigation into the unusual linkage isomerization and nitrite reduction activity of a novel tris(2-pyridyl) copper complex

NASA Astrophysics Data System (ADS)

Roger, Isolda; Wilson, Claire; Senn, Hans M.; Sproules, Stephen; Symes, Mark D.

2017-08-01

The copper-containing nitrite reductases (CuNIRs) are a class of enzymes that mediate the reduction of nitrite to nitric oxide in biological systems. Metal-ligand complexes that reproduce the salient features of the active site of CuNIRs are therefore of fundamental interest, both for elucidating the possible mode of action of the enzymes and for developing biomimetic catalysts for nitrite reduction. Herein, we describe the synthesis and characterization of a new tris(2-pyridyl) copper complex ([Cu1(NO2)2]) that binds two molecules of nitrite, and displays all three of the common binding modes for NO2-, with one nitrite bound in an asymmetric quasi-bidentate κ2-ONO manner and the other bound in a monodentate fashion with a linkage isomerism between the κ1-ONO and κ1-NO2 binding modes. We use density functional theory to help rationalize the presence of all three of these linkage isomers in one compound, before assessing the redox activity of [Cu1(NO2)2]. These latter studies show that the complex is not a competent nitrite reduction electrocatalyst in non-aqueous solvent, even in the presence of additional proton donors, a finding which may have implications for the design of biomimetic catalysts for nitrite reduction.

Nitrite produced by Mycobacterium tuberculosis in human macrophages in physiologic oxygen impacts bacterial ATP consumption and gene expression

PubMed Central

Cunningham-Bussel, Amy; Zhang, Tuo; Nathan, Carl F.

2013-01-01

In high enough concentrations, such as produced by inducible nitric oxide synthase (iNOS), reactive nitrogen species (RNS) can kill Mycobacterium tuberculosis (Mtb). Lesional macrophages in macaques and humans with tuberculosis express iNOS, and mice need iNOS to avoid succumbing rapidly to tuberculosis. However, Mtb’s own ability to produce RNS is rarely considered, perhaps because nitrate reduction to nitrite is only prominent in axenic Mtb cultures at oxygen tensions ≤1%. Here we found that cultures of Mtb-infected human macrophages cultured at physiologic oxygen tensions produced copious nitrite. Surprisingly, the nitrite arose from the Mtb, not the macrophages. Mtb responded to nitrite by ceasing growth; elevating levels of ATP through reduced consumption; and altering the expression of 120 genes associated with adaptation to acid, hypoxia, nitric oxide, oxidative stress, and iron deprivation. The transcriptomic effect of endogenous nitrite was distinct from that of nitric oxide. Thus, whether or not Mtb is hypoxic, the host expresses iNOS, or hypoxia impairs the action of iNOS, Mtb in vivo is likely to encounter RNS by producing nitrite. Endogenous nitrite may slow Mtb’s growth and prepare it to resist host stresses while the pathogen waits for immunopathology to promote its transmission. PMID:24145454

Effect of nitrate and nitrite curing salts on microbial changes and sensory quality of non-fermented sausages.

PubMed

Sanz, Y; Vila, R; Toldrá, F; Flores, J

1998-07-21

The effects of nitrate and nitrite curing salts on microbial changes and sensory quality of non-fermented sausages of small diameter were investigated. During pre-ripening (day 5), levels of lactic acid bacteria and yeasts were slightly higher in nitrite-made sausages than in those made with nitrate. In contrast, nitrite discouraged the growth of psychrotrophs as occurs in fermented sausages. By the end of ripening (day 26), levels of microorganisms were similar in both batches of sausages except for psychrotrophs being higher in those made with nitrite. Nitrate-made sausages showed higher aroma and taste intensity.

Acidified nitrite inhibits proliferation of Listeria monocytogenes - Transcriptional analysis of a preservation method.

PubMed

Müller-Herbst, Stefanie; Wüstner, Stefanie; Kabisch, Jan; Pichner, Rohtraud; Scherer, Siegfried

2016-06-02

Sodium nitrite (NaNO2) is added as a preservative during raw meat processing such as raw sausage production to inhibit growth of pathogenic bacteria. In the present study it was shown in challenge assays that the addition of sodium nitrite indeed inhibited growth and survival of Listeria monocytogenes in short-ripened spreadable raw sausages. Furthermore, in vitro growth analyses were performed, which took into account combinations of various parameters of the raw sausage ripening process like temperature, oxygen availability, pH, NaCl concentration, and absence or presence of NaNO2. Data based on 300 growth conditions revealed that the inhibitory effect of nitrite was most prominent in combination with acidification, a combination that is also achieved during short-ripened spreadable raw sausage production. At pH6.0 and below, L. monocytogenes was unable to replicate in the presence of 200mg/l NaNO2. During the adaptation of L. monocytogenes to acidified nitrite stress (pH6.0, 200mg/l NaNO2) in comparison to acid exposure only (pH6.0, 0mg/l NaNO2), a massive transcriptional adaptation was observed using microarray analyses. In total, 202 genes were up-regulated and 204 genes were down-regulated. In accordance with growth inhibition, a down-regulation of genes encoding for proteins which are involved in central cellular processes, like cell wall/membrane/envelope biogenesis, translation and ribosomal structure and biogenesis, transcription, and replication, recombination and repair, was observed. Among the up-regulated genes the most prominent group belonged to poorly characterized genes. A considerable fraction of the up-regulated genes has been shown previously to be up-regulated intracellularly in macrophages, after exposure to acid shock or to be part of the SigB regulon. These data indicate that the adaptation to acidified nitrite partly overlaps with the adaptation to stress conditions being present during host colonization. Copyright © 2016 Elsevier B.V. All rights reserved.

Structures, internal rotor potentials, and thermochemical properties for a series of nitrocarbonyls, nitroolefins, corresponding nitrites, and their carbon centered radicals.

PubMed

Snitsiriwat, Suarwee; Asatryan, Rubik; Bozzelli, Joseph W

2011-12-01

Structures, enthalpy (Δ(f)H°(298)), entropy (S°(T)), and heat capacity (C(p)(T)) are determined for a series of nitrocarbonyls, nitroolefins, corresponding nitrites, and their carbon centered radicals using the density functional B3LYP and composite CBS-QB3 calculations. Enthalpies of formation (Δ(f)H°(298)) are determined at the B3LYP/6-31G(d,p), B3LYP/6-31+G(2d,2p), and composite CBS-QB3 levels using several work reactions for each species. Entropy (S) and heat capacity (C(p)(T)) values from vibration, translational, and external rotational contributions are calculated using the rigid-rotor-harmonic-oscillator approximation based on the vibration frequencies and structures obtained from the density functional studies. Contribution to Δ(f)H(T), S, and C(p)(T) from the analysis on the internal rotors is included. Recommended values for enthalpies of formation of the most stable conformers of nitroacetone cc(═o)cno2, acetonitrite cc(═o)ono, nitroacetate cc(═o)no2, and acetyl nitrite cc(═o)ono are -51.6 kcal mol(-1), -51.3 kcal mol(-1), -45.4 kcal mol(-1), and -58.2 kcal mol(-1), respectively. The calculated Δ(f)H°(298) for nitroethylene c═cno2 is 7.6 kcal mol(-1) and for vinyl nitrite c═cono is 7.2 kcal mol(-1). We also found an unusual phenomena: an intramolecular transfer reaction (isomerization) with a low barrier (3.6 kcal mol(-1)) in the acetyl nitrite. The NO of the nitrite (R-ONO) in CH(3)C(═O')ONO moves to the C═O' oxygen in a motion of a stretching frequency and then a shift to the carbonyl oxygen (marked as O' for illustration purposes). © 2011 American Chemical Society

Nitrates and Nitrites TNC Presentation

EPA Pesticide Factsheets

The Nitrates and Nitrites Presentation gives an overview of nitrates and nitrites in drinking water, why it is important to monitor them and what to do in cases where the results exceed the maximum contaminant level (MCL).

Nitrites in Urine

MedlinePlus

... Why do I need a nitrites in urine test? Your health care provider may have ordered a urinalysis as part ... Fever What happens during a nitrites in urine test? Your health care provider will need to collect a sample of ...

Cannabinoid effects on β amyloid fibril and aggregate formation, neuronal and microglial-activated neurotoxicity in vitro.

PubMed

Janefjord, Emelie; Mååg, Jesper L V; Harvey, Benjamin S; Smid, Scott D

2014-01-01

Cannabinoid (CB) ligands have demonstrated neuroprotective properties. In this study we compared the effects of a diverse set of CB ligands against β amyloid-mediated neuronal toxicity and activated microglial-conditioned media-based neurotoxicity in vitro, and compared this with a capacity to directly alter β amyloid (Aβ) fibril or aggregate formation. Neuroblastoma (SH-SY5Y) cells were exposed to Aβ1-42 directly or microglial (BV-2 cells) conditioned media activated with lipopolysaccharide (LPS) in the presence of the CB1 receptor-selective agonist ACEA, CB2 receptor-selective agonist JWH-015, phytocannabinoids Δ(9)-THC and cannabidiol (CBD), the endocannabinoids 2-arachidonoyl glycerol (2-AG) and anandamide or putative GPR18/GPR55 ligands O-1602 and abnormal-cannabidiol (Abn-CBD). TNF-α and nitrite production was measured in BV-2 cells to compare activation via LPS or albumin with Aβ1-42. Aβ1-42 evoked a concentration-dependent loss of cell viability in SH-SY5Y cells but negligible TNF-α and nitrite production in BV-2 cells compared to albumin or LPS. Both albumin and LPS-activated BV-2 conditioned media significantly reduced neuronal cell viability but were directly innocuous to SH-SY5Y cells. Of those CB ligands tested, only 2-AG and CBD were directly protective against Aβ-evoked SH-SY5Y cell viability, whereas JWH-015, THC, CBD, Abn-CBD and O-1602 all protected SH-SY5Y cells from BV-2 conditioned media activated via LPS. While CB ligands variably altered the morphology of Aβ fibrils and aggregates, there was no clear correlation between effects on Aβ morphology and neuroprotective actions. These findings indicate a neuroprotective action of CB ligands via actions at microglial and neuronal cells.

Nisin: a possible alternative or adjunct to nitrite in the preservation of meats.

PubMed Central

Rayman, M K; Aris, B; Hurst, A

1981-01-01

Nisin at 75 ppm (75 microgram/g) was superior to 150 ppm of nitrite in inhibiting outgrowth of Clostridium sporogenes PA3679 spores in meat slurries, which had been heated to simulate the process used for cooked ham. The inhibitory activity of nisin decreased as the spore load or pH of the slurries increased. Unlike nitrite, inhibition by nisin was unaffected by high levels of iron either as a constituent of meats or when added as an iron salt. In slurries treated with 75 ppm of nisin, refrigerated storage for 56 days resulted in depletion of nisin to a level low enough to allow outgrowth within 3 to 10 days if the slurries were subsequently abused at 35 degrees C. In contrast, a combination of 40 ppm of nitrite and either 75 or 100 ppm of nisin almost completely inhibited outgrowth in these slurries. The nisin-nitrite combination appeared to have a synergistic effect, and the low concentration of nitrite was sufficient to preserve the color in meats similar to that of products cured with 150 ppm of nitrite. PMID:7195188

Use of gamma radiation on control of Clostridium botulinum in mortadella formulated with different nitrite levels

NASA Astrophysics Data System (ADS)

Dutra, Monalisa Pereira; Aleixo, Glécia de Cássia; Ramos, Alcinéia de Lemos Souza; Silva, Maurício Henriques Louzada; Pereira, Marcio Tadeu; Piccoli, Roberta Hilsdorf; Ramos, Eduardo Mendes

2016-02-01

This study investigated the effects of applying different doses of gamma radiation (0, 10 and 20 kGy) on Clostridium botulinum spores (107 spores/g) inoculated into mortadellas with different nitrite contents (0, 150 and 300 ppm). We also evaluated the order of application of heat (cooking) and irradiation processing. The products were evaluated for survival of C. botulinum, pH, water activity (Aw), redox potential (Eh) and residual nitrite content. In the non-irradiated raw batters, almost all spores could be recovered when no nitrite was added and only half was recovered with the addition of 150 ppm of nitrite. The use of 150 ppm of nitrite was able to inhibit the germination or growth of C. botulinum in non-irradiated cooked mortadellas after 48 h of processing. However, after 30 days of chilling storage (4 °C), it was possible to recover 105 UFC/g of this microorganism. The gamma irradiation (>10 kGy) had a positive effect on the inactivation of C. botulinum in mortadellas, independent of the sodium nitrite level used and the cooking/irradiation processing order.

Sorbate-nitrite interactions: acetonitrile oxide as an alkylating agent.

PubMed

Pérez-Prior, M Teresa; Gómez-Bombarelli, Rafael; González-Pérez, Marina; Manso, José A; García-Santos, M Pilar; Calle, Emilio; Casado, Julio

2009-07-01

Because chemical species with DNA-damaging and mutagenic activity are formed in sorbate-nitrite mixtures and because sorbic acid sometimes coexists with nitrite occurring naturally or incorporated as a food additive, the study of sorbate-nitrite interactions is important. Here, the alkylating potential of the products resulting from such interactions was investigated. Drawn were the following conclusions: (i) Acetonitrile oxide (ACNO) is the compound responsible for the alkylating capacity of sorbate-nitrite mixtures; (ii) ACNO alkylates 4-(p-nitrobenzyl)pyridine (NBP), a trap for alkylating agents with nucleophilic characteristics similar to those of DNA bases, forming an adduct (AD; epsilon = 1.4 x 10(4) M(-1) cm(-1); lambda = 519 nm); (iii) the NBP alkylation reaction complies with the rate equation, r = d[AD]/dt = k(alk)(ACNO)[ACNO][NBP]-k(hyd)(AD)[AD], k(alk)(ACNO) being the NBP alkylation rate constant for ACNO and k(hyd)(AD) the rate constant for the adduct hydrolysis reaction; (iv) the small fraction of ACNO forming the adduct with NBP, as well as the small magnitude of the quotient (k(alk) (ACNO)/k(hyd)(ACNO)) as compared with those reported for other alkylating agents, such as some lactones and N-alkyl-N-nitrosoureas, reveals the ACNO effective alkylating capacity to be less significant; (v) the low value of the NBP-ACNO adduct life (defined as the total amount of adduct present along the progression of the NBP alkylation per unit of alkylating agent concentration) points to the high instability of this adduct; and (vi) the obtained results are in accordance with the low carcinogenicity of ACNO.

Can the Griess Nitrite Test and a Urinary Pus Cell Count of ≥5 Cells Per Micro Litre of Urine in Pregnant Women be Used for the Screening or the Early Detection of Urinary Tract Infections in Rural India?

PubMed

Thakre, Sushama S; Dhakne, Supriya S; Thakre, Subhash B; Thakre, Amol D; Ughade, Suresh M; Kale, Priya

2012-11-01

Urinary Tract Infection (UTI) is a common problem in pregnancy due to the morphological and the physiological changes that take place in the genitourinary tract during pregnancy. Screening methods may be useful, because a full bacteriological analysis could be reserved for those patients who are symptomatic or those who have positive screening test results. The exact prevalence of UTI in rural, pregnant women is unknown. The present study was undertaken to estimate the prevalence of UTI in pregnant women and for ascertaining the utility of the Griess Nitrite test and the Urinary Pus Cell Count of ≥5 cells per micro litre test for the screening or the early detection of UTI in them at primary health care clinics. Occurrence of urinary complaints was compared in UTI and non UTI women. We conducted a study on 300 randomly selected, pregnant women from rural areas. Urine cultures, pus-cell counts and the Griess nitrite test were used for diagnosis of UTI. The screening tests for UTI were evaluated in terms of their sensitivity, specificity, Positive Predictive Value (PPV), Negative Predictive Value (NPV) and the percentage of correctly classified. In the present study, the prevalence of UTI was found to be 29/300 (9.6%, 95% confidence interval 9.57-9.63). The specificities of the two screening tests were comparable (97.05% and 94.47%). Also, the negative predictive values of the two tests were almost similar (97.77% and 96.96%). The percentage of correctly classified by the Griess nitrite test and the urine pus cell count were found to be 95.33% and 92.33% respectively. The proportion of the women with various urinary complaints was significantly higher (P<0.00) in the UTI subjects as compared to that in the non-UTI subjects. Urine culture remains the gold standard for the detection of asymptomatic bacteriuria. The Nitrite test of uncentrifuged urine was observed to be the best among the screening tests which were evaluated in terms of their efficiency and validity.

Methaemoglobinaemia due to amyl nitrite inhalation: a case report.

PubMed

Machabert, R; Testud, F; Descotes, J

1994-05-01

Methaemoglobinaemia is a potential toxic effect of aliphatic nitrites which are increasingly abused by male homosexuals and drug addicts because of marked vasodilating properties ('poppers'). In most instances, severe complications were described following the ingestion of large quantities of amyl, butyl or isobutyl nitrites. A deficiency in NADH-dependent haemoglobin reductase in some patients has been noted. This is the first report of symptomatic methaemoglobinaemia following the inhalation of amyl nitrite.

Current perspectives and challenges in understanding the role of nitrite as an integral player in nitric oxide biology and therapy

PubMed Central

Vitturi, Dario A.; Patel, Rakesh P.

2011-01-01

Beyond an inert oxidation product of nitric oxide (NO) metabolism, current thinking posits a key role for nitrite as a mediator of NO-signaling, especially during hypoxia. This concept has been discussed both in the context of nitrite serving a role as an endogenous modulator of NO-homeostasis, but also from a novel clinical perspective whereby nitrite therapy may replete NO-signaling and prevent ischemic tissue injury. Indeed, the relatively rapid translation of studies delineating mechanisms of action to ongoing and planned clinical trials has been critical in fuelling interest in nitrite biology and several excellent reviews have been written on this topic. In this article we limit our discussions to current concepts, and what we feel are questions that remain unanswered within the paradigm of nitrite being a mediator of NO biology. PMID:21683783

Growth of Staphylococcus and Salmonella on Frankfurters With and Without Sodium Nitrite

PubMed Central

Bayne, Henry G.; Michener, H. David

1975-01-01

Conventional and nitrite-free frankfurters in loosely wrapped packages were compared as to their ability to support growth of Salmonella, Staphylococcus, and their naturally occurring spoilage flora at 7 C (simulating refrigerated storage) and 20 C (simulating possible temperature abuse). At 7 C Salmonella did not grow in either type of frankfurter; Staphylococcus and the natural spoilage flora sometimes grew more rapidly in the absence of nitrite, but the difference was not significant. At 20 C growth of Salmonella, Staphylococcus, and of the spoilage flora was, at most, only slightly faster on nitrite-free frankfurters. Salmonella was not suppressed in broth culture experiments at the pH and nitrite content found in frankfurters. Although either type of frankfurter can become hazardous due to growth of Salmonella or Staphylococcus, no unusual or additional hazard resulted from the omission of nitrite from frankfurters. PMID:952

Physiological and biochemical responses resulting from nitrite accumulation in tomato (Lycopersicon esculentum Mill. cv. Ibiza F1).

PubMed

Ezzine, Monia; Ghorbel, Mohamed Habib

2006-10-01

The sensitivity of hydroponically cultivated tomato (Lycopersicon esculentum Mill. cv. Ibiza F1) submitted to nitrite treatments (0.25-10mM KNO(2)) for 7d was studied. Increasing nitrite levels in the culture medium led to several disruptions of tomato plants, reflected by reductions of both dry matter per plant, chlorophyll concentrations and the appearance of chlorosis symptoms at the leaf surface. This behaviour was accompanied by stimulation of nitrite, nitrate and ammonia ion accumulation, mainly in roots and old leaves. Higher proteolytic and gaiacol peroxidase (GPX, EC. 1.11.1.7) activities and malonyldialdehyde content were also noted. Protein content of the different plant organs was decreased by nitrite treatment. These physiological and biochemical parameters were chosen as they are stress indicators. Taken together, our data partly explain the harmful effects of nitrite ions, when excessive in the culture medium.

Biological nitrogen removal from sewage via anammox: Recent advances.

PubMed

Ma, Bin; Wang, Shanyun; Cao, Shenbin; Miao, Yuanyuan; Jia, Fangxu; Du, Rui; Peng, Yongzhen

2016-01-01

Biological nitrogen removal from sewage via anammox is a promising and feasible technology to make sewage treatment energy-neutral or energy-positive. Good retention of anammox bacteria is the premise of achieving sewage treatment via anammox. Therefore the anammox metabolism and its factors were critically reviewed so as to form biofilm/granules for retaining anammox bacteria. A stable supply of nitrite for anammox bacteria is a real bottleneck for applying anammox in sewage treatment. Nitritation and partial-denitrification are two promising methods of offering nitrite. As such, the strategies for achieving nitritation in sewage treatment were summarized by reviewing the factors affecting nitrite oxidation bacteria growth. Meanwhile, the methods of achieving partial-denitrification have been developed through understanding the microorganisms related with nitrite accumulation and their factors. Furthermore, two cases of applying anammox in the mainstream sewage treatment plants were documented. Copyright © 2015 Elsevier Ltd. All rights reserved.

Universal chemiluminescence flow-through device based on directed self-assembly of solid-state organic chromophores on layered double hydroxide matrix.

PubMed

Wang, Zhihua; Teng, Xu; Lu, Chao

2013-02-19

In this work, a universal chemiluminescence (CL) flow-through device suitable for various CL resonance energy transfer (CRET) systems has been successfully fabricated. Highly efficient CRET in solid-state photoactive organic molecules can be achieved by assembling them on the surface of layered double hydroxides (LDHs). We attribute these observations to the suppression of the intermolecular π-π stacking interactions among aromatic rings and the improvement of molecular orientation and planarity in the LDH matrix, enabling a remarkable increase in fluorescence lifetime and quantum yield of organic molecules. Under optimal conditions, using peroxynitrous acid-fluorescein dianion (FLUD) as a model CRET system, trace FLUD (10 μM) was assembled on the surface of LDHs. Peroxynitrous acid/nitrite could be assayed in the range of 1.0-500 μM, and the detection limit for peroxynitrous acid/nitrite (S/N = 3) was 0.6 μM. This CL flow-through device exhibited operational stability, high reproducibility, and long lifetime. While LDHs were immobilized in a flow-through device in the absence of FLUD, the detection limit for peroxynitrous acid/nitrite was 100 μM. On the other hand, FLUD at the same concentration can not enhance the CL intensity of peroxynitrous acid system. This fabricated CL flow-through column has been successfully applied to determine nitrite in sausage samples with recoveries of 98-102%. These satisfactory results demonstrated that our studies pave a novel way toward flow-through column-based CRET using solid-state organic molecules as acceptors for signal amplification.

Aeration control strategies to stimulate simultaneous nitrification-denitrification via nitrite during the formation of aerobic granular sludge.

PubMed

Dobbeleers, Thomas; D'aes, Jolien; Miele, Solange; Caluwé, Michel; Akkermans, Veerle; Daens, Dominique; Geuens, Luc; Dries, Jan

2017-09-01

In this study, a sequencing batch reactor (SBR), treating synthetic wastewater (COD/N = 5), was operated in two stages. During stage I, an aeration control strategy based on oxygen uptake rate (OUR) was applied, to accomplish nitrogen removal via nitrite >80%. In stage II, the development of aerobic granular sludge (AGS) was examined while two aeration control strategies (OUR and pH slope) maintained the nitrite pathway and optimized the simultaneous nitrification-denitrification (SND) performance. Stimulation of slow-growing organisms, (denitrifying) polyphosphate-accumulating organisms (D)PAO and (denitrifying) glycogen-accumulating organisms (D)GAO leads to full granulation (at day 200, SVI 10  = 47.0 mL/g and SVI 30  = 43.1 mL/g). The average biological nutrient removal efficiencies, for nitrogen and phosphorus, were 94.6 and 83.7%, respectively. Furthermore, the benefits of an increased dissolved oxygen concentration (1.0-2.0 mg O 2 /L) were shown as biomass concentrations increased with approximately 2 g/L, and specific ammonium removal rate and phosphorus uptake rate increased with 33 and 44%, respectively. It was shown that the combination of both aeration phase-length control strategies provided an innovative method to achieve SND via nitrite in AGS.

Color compensation in nitrite-reduced meat batters incorporating paprika or tomato paste.

PubMed

Bázan-Lugo, Eduardo; García-Martínez, Ignacio; Alfaro-Rodríguez, Rosa Hayde; Totosaus, Alfonso

2012-06-01

Nitrite is a key ingredient the manufacture of meat products, forming a stable pink color characteristic of cured products, retarding the development of rancidity and off-odors and flavors during storage, and preventing microbial growth. The negative aspects of nitrite and the demands for healthy foods result in the need to reduce nitrite in cured meat products. Paprika or tomato has been employed as natural pigments in meat products. The objective of this work was to determine the effect of incorporating paprika powder or tomato paste on the texture, rancidity and instrumental and sensory color compensation in nitrite-reduced meat batters. Addition of tomato paste improved moisture content, resulting in harder but less cohesive samples as compared to control and paprika-containing meat batters. Color characteristics of reduced nitrite samples obtained higher a* red coloration (8.9 for paprika and 7.7-8.0 for tomato paste), as compared to control samples (5.65). Instrumental color was low in control samples, with high values for tomato paste and paprika samples. Nonetheless, tomato paste used to compensate color in nitrite-reduced meat batters was ranked closer to the control sample in sensory evaluation. Color characteristics-instrumental and sensory-in these kinds of meat products were enhanced by the addition of 2.5-3.0% of tomato paste, presenting results close to the non-reduced nitrite control. Similarly, antioxidant components of tomato paste or paprika reduced lipid oxidation. Nitrite reduction from 150 to 100 ppm could be achieved employing tomato paste as a natural pigment to improve color and texture. Copyright © 2011 Society of Chemical Industry.

Corn leaf nitrate reductase - A nontoxic alternative to cadmium for photometric nitrate determinations in water samples by air-segmented continuous-flow analysis

USGS Publications Warehouse

Patton, C.J.; Fischer, A.E.; Campbell, W.H.; Campbell, E.R.

2002-01-01

Development, characterization, and operational details of an enzymatic, air-segmented continuous-flow analytical method for colorimetric determination of nitrate + nitrite in natural-water samples is described. This method is similar to U.S. Environmental Protection Agency method 353.2 and U.S. Geological Survey method 1-2545-90 except that nitrate is reduced to nitrite by soluble nitrate reductase (NaR, EC 1.6.6.1) purified from corn leaves rather than a packed-bed cadmium reactor. A three-channel, air-segmented continuous-flow analyzer-configured for simultaneous determination of nitrite (0.020-1.000 mg-N/L) and nitrate + nitrite (0.05-5.00 mg-N/L) by the nitrate reductase and cadmium reduction methods-was used to characterize analytical performance of the enzymatic reduction method. At a sampling rate of 90 h-1, sample interaction was less than 1% for all three methods. Method detection limits were 0.001 mg of NO2- -N/L for nitrite, 0.003 mg of NO3-+ NO2- -N/L for nitrate + nitrite by the cadmium-reduction method, and 0.006 mg of NO3- + NO2- -N/L for nitrate + nitrite by the enzymatic-reduction method. Reduction of nitrate to nitrite by both methods was greater than 95% complete over the entire calibration range. The difference between the means of nitrate + nitrite concentrations in 124 natural-water samples determined simultaneously by the two methods was not significantly different from zero at the p = 0.05 level.

Biodegradation of 2-nitrotoluene by Micrococcus sp. strain SMN-1.

PubMed

Mulla, Sikandar I; Hoskeri, Robertcyril S; Shouche, Yogesh S; Ninnekar, Harichandra Z

2011-02-01

A bacterial consortium capable of degrading nitroaromatic compounds was isolated from pesticide-contaminated soil samples by selective enrichment on 2-nitrotoluene as a sole source of carbon and energy. The three different bacterial isolates obtained from bacterial consortium were identified as Bacillus sp. (A and C), Bacillus flexus (B) and Micrococcus sp. (D) on the basis of their morphological and biochemical characteristics and by phylogenetic analysis based on 16S rRNA gene sequences. The pathway for the degradation of 2-nitrotoluene by Micrococcus sp. strain SMN-1 was elucidated by the isolation and identification of metabolites, growth and enzymatic studies. The organism degraded 2-nitrotoluene through 3-methylcatechol by a meta-cleavage pathway, with release of nitrite.

Carbon-Fiber Nitrite Microsensor for In Situ Biofilm Monitoring

EPA Science Inventory

During nitrification, nitrite is produced as an intermediate when ammonia is oxidized to nitrate. It is well established that nitrifying biofilm are involved in nitrification episodes in chloraminated drinking water distribution systems with nitrite accumulation occurring during ...

Carbon-Fiber Nitrite Microsensor for In Situ Biofilm Monitoring

EPA Science Inventory

During nitrification, nitrite is produced as an intermediate when ammonia is oxidized to nitrate. It is well established that nitrifying biofilm are involved in nitrification episodes in chloraminated drinking water distribution systems with nitrite accumulation occurring during...

Comparison of the Effect of Curing Ingredients Derived from Purified and Natural Sources on Inhibition of Clostridium perfringens Outgrowth during Cooling of Deli-Style Turkey Breast.

PubMed

King, Amanda M; Glass, Kathleen A; Milkowski, Andrew L; Sindelar, Jeffrey J

2015-08-01

The antimicrobial impact of purified and natural sources of both nitrite and ascorbate were evaluated against Clostridium perfringens during the postthermal processing cooling period of deli-style turkey breast. The objective of phase I was to assess comparable concentrations of nitrite (0 or 100 ppm) and ascorbate (0 or 547 ppm) from both purified and natural sources. Phase II was conducted to investigate concentrations of nitrite (50, 75, or 100 ppm) from cultured celery juice powder and ascorbate (0, 250, or 500 ppm) from cherry powder to simulate alternative curing formulations. Ground turkey breast (75% moisture, 1.2% salt, pH 6.2) treatments were inoculated with C. perfringens spores (three-strain mixture) to yield 2.5 log CFU/g. Individual 50-g portions were vacuum packaged, cooked to 71.1°C, and chilled from 54.4 to 26.7°C in 5 h and from 26.7 to 7.2°C in 10 additional hours. Triplicate samples were assayed for growth of C. perfringens at predetermined intervals by plating on tryptose-sulfite-cycloserine agar; experiments were replicated three times. In phase I, uncured, purified nitrite, and natural nitrite treatments without ascorbate had 5.3-, 4.2-, and 4.4-log increases in C. perfringens, respectively, at 15 h, but <1-log increase was observed at the end of chilling in treatments containing 100 ppm of nitrite and 547 ppm of ascorbate from either source. In phase II, 0, 50, 75, and 100 ppm of nitrite and 50 ppm of nitrite plus 250 ppm of ascorbate supported 4.5-, 3.9-, 3.5-, 2.2-, and 1.5-log increases in C. perfringens, respectively. In contrast, <1-log increase was observed after 15 h in the remaining phase II treatments supplemented with 50 ppm of nitrite and 500 ppm of ascorbate or ≥75 ppm of nitrite and ≥250 ppm of ascorbate. These results confirm that equivalent concentrations of nitrite, regardless of the source, provide similar inhibition of C. perfringens during chilling and that ascorbate enhances the antimicrobial effect of nitrite on C. perfringens at concentrations commonly used in alternative cured meats.

N2O production by nitrifier denitrification in the Benguela Upwelling System

NASA Astrophysics Data System (ADS)

Frame, C. H.; Hou, L.; Lehmann, M. F.

2014-12-01

The Benguela upwelling system off the coast of southwestern Africa is an important zone of marine N2O production whose upwelling rates vary seasonally. Here we present N2O stable isotopic and isotopomeric data collected during a period of high upwelling (September 2013) and low upwelling (January 2014). During both periods, 15N-nitrite and 15N-ammonium tracer inucbation experiments were used to investigate N2O production by ammonia oxidizing microorganisms in the top 150m of the water column. N2O production from 15N-ammonium was not measurable during these incubations. However, we detected N2O production from 15N-nitrite, suggesting that nitrifier denitrification is a source of shallow N2O in this region. Furthermore, decreasing the pH of the incubation water enhanced the amount of N2O produced, suggesting that upwelling of CO2-rich/low-pH deep water may enhance N2O production in this region. Finally, we present our incubation data in the larger context of the N2O and nitrite isotopic and concentration profiles, with an eye toward comparing incubation-based N2O production rates with profile-based estimates.

Activation of nitrite. [Interaction of amino compounds to form carcinogenic N-nitroso compounds in digestive tract of animals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lijinsky, W.

At low doses dietary nitrite has no obvious deleterious effect, even when ingested for long periods, and nitrites have been used for a long time as flavoring and coloring additives to meat and fish and as preservatives in food in which there is a danger of botulism. In recent years there has been increasing concern that one form of activation of nitrite might be related to cancer. That is the property of interaction with amino compounds to form N-nitroso compounds, which are potent chemical carcinogens. Results are reported from studies on the carcinogenic effects of nitrite and amines in rats.more » (CH)« less

Inhibition of nitrite-induced toxicity in channel catfish by calcium chloride and sodium chloride

USGS Publications Warehouse

Tommasso J.R., Wright; Simco, B.A.; Davis, K.B.

1980-01-01

Environmental chloride has been shown to inhibit methemoglobin formation in fish, thereby offering a protective effect against nitrite toxicity. Channel catfish (Ictalurus punctatus) were simultaneously exposed to various environmental nitrite and chloride levels (as either CaCl2 or NaCl) in dechlorinated tap water (40 mg/L total hardness, 47 mg/L alkalinity, 4 mg/L chloride, pH = 6.9-7.1, and temperature 21-24°C). Methemoglobin levels in fish simultaneously exposed to 2.5 mg/L nitrite and up to 30 mg/L chloride as either CaCl2 or NaCl were similar but significantly lower than in unprotected fish. Exposure to 10 mg/L nitrite and 60 mg/L chloride resulted in methemoglobin levels similar to those of the controls; most unprotected fish died. Fish exposed to 10 mg/L nitrite had significantly lower methemoglobin levels when protected with 15.0 mg/L chloride as CaCl2 than with NaCl. Fish exposed to nitrite in the presence of 60 mg/L chloride (as either CaCl2 or NaCl) had similar 24-h LC50 values that were significantly elevated above those obtained in the absence of chloride. Calcium had little effect on tolerance to nitrite toxicity in channel catfish in contrast to its large effect reported in steelhead trout (Salmo gairdneri).

Inhibition of toxigenesis of group II (nonproteolytic) Clostridium botulinum type B in meat products by using a reduced level of nitrite.

PubMed

Keto-Timonen, Riikka; Lindström, Miia; Puolanne, Eero; Niemistö, Markku; Korkeala, Hannu

2012-07-01

The effect of three different concentrations of sodium nitrite (0, 75, and 120 mg/kg) on growth and toxigenesis of group II (nonproteolytic) Clostridium botulinum type B was studied in Finnish wiener-type sausage, bologna-type sausage, and cooked ham. A low level of inoculum (2.0 log CFU/g) was used for wiener-type sausage and bologna-type sausage, and both low (2.0 log CFU/g) and high (4.0 log CFU/g) levels were used for cooked ham. The products were formulated and processed under simulated commercial conditions and stored at 8°C for 5 weeks. C. botulinum counts were determined in five replicate samples of each nitrite concentration at 1, 3, and 5 weeks after thermal processing. All samples were positive for C. botulinum type B. The highest C. botulinum counts were detected in nitrite-free products. Toxigenesis was observed in nitrite-free products during storage, but products containing either 75 or 120 mg/kg nitrite remained nontoxic during the 5-week study period, suggesting that spores surviving the heat treatment were unable to germinate and develop into a toxic culture in the presence of nitrite. The results suggest that the safety of processed meat products with respect to group II C. botulinum type B can be maintained even with a reduced concentration (75 mg/kg) of sodium nitrite.

Effect of inhaled nitric oxide on cerebrospinal fluid and blood nitrite concentrations in newborn lambs

PubMed Central

Conahey, George R.; Power, Gordon G.; Hopper, Andrew O.; Terry, Michael H.; Kirby, Laura S.; Blood, Arlin B.

2009-01-01

Inhaled nitric oxide (iNO) has many extrapulmonary effects. As the half-life of NO in blood is orders of magnitude less than the circulation time from lungs to the brain, the mediator of systemic effects of iNO is unknown. We hypothesized that concentrations of nitrite, a circulating byproduct of NO with demonstrated NO bioactivity, would increase in blood and cerebrospinal fluid (CSF) during iNO therapy. iNO (80ppm) was given to six newborn lambs and results compared to six control lambs. Blood and CSF nitrite concentrations increased two-fold in response to iNO. cGMP increased in blood but not CSF suggesting brain guanylate cyclase activity was not increased. When sodium nitrite was infused intravenously blood and CSF nitrite levels increased within 10 min and reached similar levels of 14.6±1.5 µM after 40 min. The reactivity of nitrite in hemoglobin-free brain homogenates was investigated, with the findings that nitrite did not disappear nor did measurable amounts of s-nitroso, n-nitroso, or iron-nitrosyl-species appear. We conclude that although nitrite diffuses freely between blood and CSF, due to its lack of reactivity in the brain, nitrite’s putative role as the mediator of the systemic effects of iNO is limited to intravascular reactions. PMID:18535482

Nitrate reductase and nitrite as additional components of defense system in pigeonpea (Cajanus cajan L.) against Helicoverpa armigera herbivory.

PubMed

Kaur, Rimaljeet; Gupta, Anil Kumar; Taggar, Gaurav Kumar

2014-10-01

Amylase inhibitors serve as attractive candidates of defense mechanisms against insect attack. Therefore, the impediment of Helicoverpa armigera digestion can be the effective way of controlling this pest population. Nitrite was found to be a potent mixed non-competitive competitive inhibitor of partially purified α-amylase of H. armigera gut. This observation impelled us to determine the response of nitrite and nitrate reductase (NR) towards H. armigera infestation in nine pigeonpea genotypes (four moderately resistant, three intermediate and two moderately susceptible). The significant upregulation of NR in moderately resistant genotypes after pod borer infestation suggested NR as one of the factors that determine their resistance status against insect attack. The pod borer attack caused greater reduction of nitrate and significant accumulation of nitrite in moderately resistant genotypes. The activity of nitrite reductase (NiR) was also enhanced more in moderately resistant genotypes than moderately susceptible genotypes on account of H. armigera herbivory. Expression of resistance to H. armigera was further revealed when significant negative association between NR, NiR, nitrite and percent pod damage was observed. This is the first report that suggests nitrite to be a potent inhibitor of H. armigera α-amylase and also the involvement of nitrite and NR in providing resistance against H. armigera herbivory. Copyright © 2014 Elsevier Inc. All rights reserved.

Short-Term Effects of a High Nitrate Diet on Nitrate Metabolism in Healthy Individuals

PubMed Central

Bondonno, Catherine P.; Liu, Alex H.; Croft, Kevin D.; Ward, Natalie C.; Puddey, Ian B.; Woodman, Richard J.; Hodgson, Jonathan M.

2015-01-01

Dietary nitrate, through the enterosalivary nitrate-nitrite-NO pathway, can improve blood pressure and arterial stiffness. How long systemic nitrate and nitrite remain elevated following cessation of high nitrate intake is unknown. In 19 healthy men and women, the time for salivary and plasma nitrate and nitrite to return to baseline after 7 days increased nitrate intake from green leafy vegetables was determined. Salivary and plasma nitrate and nitrite was measured at baseline [D0], end of high nitrate diet [D7], day 9 [+2D], day 14 [+7D] and day 21 [+14D]. Urinary nitrite and nitrate was assessed at D7 and +14D. Increased dietary nitrate for 7 days resulted in a more than fourfold increase in saliva and plasma nitrate and nitrite (p < 0.001) measured at [D7]. At [+2D] plasma nitrite and nitrate had returned to baseline while saliva nitrate and nitrite were more than 1.5 times higher than at baseline levels. By [+7D] all metabolites had returned to baseline levels. The pattern of response was similar between men and women. Urinary nitrate and nitrate was sevenfold higher at D7 compared to +14D. These results suggest that daily ingestion of nitrate may be required to maintain the physiological changes associated with high nitrate intake. PMID:25774606

Removal of ammonia solutions used in catalytic wet oxidation processes.

PubMed

Hung, Chang Mao; Lou, Jie Chung; Lin, Chia Hua

2003-08-01

Ammonia (NH(3)) is an important product used in the chemical industry, and is common place in industrial wastewater. Industrial wastewater containing ammonia is generally either toxic or has concentrations or temperatures such that direct biological treatment is unfeasible. This investigation used aqueous solutions containing more of ammonia for catalytic liquid-phase oxidation in a trickle-bed reactor (TBR) based on Cu/La/Ce composite catalysts, prepared by co-precipitation of Cu(NO(3))(2), La(NO(3))(2), and Ce(NO(3))(3) at 7:2:1 molar concentrations. The experimental results indicated that the ammonia conversion of the wet oxidation in the presence of the Cu/La/Ce composite catalysts was determined by the Cu/La/Ce catalyst. Minimal ammonia was removed from the solution by the wet oxidation in the absence of any catalyst, while approximately 91% ammonia removal was achieved by wet oxidation over the Cu/La/Ce catalyst at 230 degrees C with oxygen partial pressure of 2.0 MPa. Furthermore, the effluent streams were conducted at a liquid hourly space velocity of under 9 h(-1) in the wet catalytic processes, and a reaction pathway was found linking the oxidizing ammonia to nitric oxide, nitrogen and water. The solution contained by-products, including nitrates and nitrites. Nitrite selectivity was minimized and ammonia removal maximized when the feed ammonia solution had a pH of around 12.0.

[Hydroxylamine conversion by anammox enrichment].

PubMed

Hu, Anhui; Zheng, Ping; Lu, Huifeng; Ding, Shuang; Wang, Caihua

2010-04-01

Hydroxylamine is an important intermediate product of anammox. This study was focused on the characteristics of hydroxylamine and nitrite conversions by anammox enrichment. The changes of nitrogenous substrates and related products with time were measured using batch tests with anammox enrichment as inoculum. Since hydroxylamine didn't react with nitrite in uninoculated control culture, these two compounds were chemically stable. Both of them decreased with time in anammox enrichment inoculated cultures, in which ammonia as intermediate product would be produced and converted with the maximum concentration being 0.338 mg/L. The total nitrogen concentration decreased from 4.694 mmol/L to 0.812 mmol/L with conversion rate 82.7% in the end. When hydroxylamine and nitrite concentrations were about 2.5 mmol/L respectively, the maximum specific sludge conversion rates of hydroxylamine was 0.535 mmol/(gVSS.h), which was 1.81 times bigger than that of ammonia in ammonia reaction system; the maximum specific sludge rate of total nitrogen was slightly higher than that in ammonia reaction system. When hydroxylamine concentration increased to 5.0 mmol/L, the hydroxylamine and nitrite conversion rates promoted by 26.7% and 120.7% respectively; and the maximum ammonia accumulated was 1.810 mmol/L. When nitrite concentration increased to 5.0 mmol/L, the hydroxylamine and nitrite conversion rates promoted by 6.9% and 9.0% respectively; and the maximum ammonia accumulated was 0.795 mmol/L. Anammox enrichment was capable of converting hydroxylamine and nitrite simultaneously and had the higher conversion rate of hydroxylamine than ammonia conversion rate. Hydroxylamine and nitrite conversion rates were less affected by increase in nitrite concentration, but more significantly influenced by increase in hydroxylamine. The maximum ammonia concentration accumulated would rise as the result of increasing both hydroxylamine and nitrite. The result of experiment was consistent with pathway model presented by van de Graaf AA.

Intermediates detected by visible spectroscopy during the reaction of nitrite with deoxyhemoglobin: the effect of nitrite concentration and diphosphoglycerate.

PubMed

Nagababu, Enika; Ramasamy, Somasundaram; Rifkind, Joseph M

2007-10-16

The reaction of nitrite with deoxyhemoglobin (deoxyHb) results in the reduction of nitrite to NO, which binds unreacted deoxyHb forming Fe(II)-nitrosylhemoglobin (Hb(II)NO). The tight binding of NO to deoxyHb is, however, inconsistent with reports implicating this reaction with hypoxic vasodilation. This dilemma is resolved by the demonstration that metastable intermediates are formed in the course of the reaction of nitrite with deoxyHb. The level of intermediates is quantitated by the excess deoxyHb consumed over the concentrations of the final products formed. The dominant intermediate has a spectrum that does not correspond to that of Hb(III)NO formed when NO reacts with methemoglobin (MetHb), but is similar to metHb resulting in the spectroscopic determinations of elevated levels of metHb. It is a delocalized species involving the heme iron, the NO, and perhaps the beta-93 thiol. The putative role for red cell reacted nitrite on vasodilation is associated with reactions involving the intermediate. (1) The intermediate is less stable with a 10-fold excess of nitrite and is not detected with a 100-fold excess of nitrite. This observation is attributed to the reaction of nitrite with the intermediate producing N2O3. (2) The release of NO quantitated by the formation of Hb(II)NO is regulated by changes in the distal heme pocket as shown by the 4.5-fold decrease in the rate constant in the presence of 2,3-diphosphoglycerate. The regulated release of NO or N2O3 as well as the formation of the S-nitroso derivative of hemoglobin, which has also been reported to be formed from the intermediates generated during nitrite reduction, should be associated with any hypoxic vasodilation attributed to the RBC.

Decreased nitrite levels in erythrocytes of children with β-thalassemia/hemoglobin E.

PubMed

Suvachananonda, Thitiwat; Wankham, Amara; Srihirun, Sirada; Tanratana, Pansakorn; Unchern, Supeenun; Fucharoen, Suthat; Chuansumrit, Ampaiwan; Sirachainan, Nongnuch; Sibmooh, Nathawut

2013-09-01

Nitrite anion is bioactive nitric oxide (NO) species circulating in blood, and represents the NO bioavailability and endothelial function. In this study, we aimed to investigate the nitrite levels and the correlation with hemolysis and severity in β-thalassemia/hemoglobin E (β-thal/HbE). 38 Children (12.0±1.9 years of age) with a diagnosis of mild, moderate and severe β-thalassemia were enrolled in the study. The blood nitrite levels and potential plasma NO consumption were measured by the chemiluminescence method. The nitrite levels in whole blood and erythrocytes of the severe thalassemia subjects were lower than those of the control subjects. At day 7 after transfusion of packed erythrocytes, the nitrite levels in erythrocytes increased. The plasma hemoglobin and NO consumption increased in the severe thalassemia subjects. The nitrite levels in erythrocytes inversely correlated with plasma hemoglobin, lactate dehydrogenase activity, potential NO consumption, and lipid peroxidation. Our studies demonstrate the decreased NO bioavailability in thalassemia, which could result from endothelial dysfunction, the increased potential NO consumption in plasma by cell-free hemoglobin and oxidative stress. Copyright © 2013 Elsevier Inc. All rights reserved.

Molecular Components of Nitrate and Nitrite Efflux in Yeast

PubMed Central

Cabrera, Elisa; González-Montelongo, Rafaela; Giraldez, Teresa; de la Rosa, Diego Alvarez

2014-01-01

Some eukaryotes, such as plant and fungi, are capable of utilizing nitrate as the sole nitrogen source. Once transported into the cell, nitrate is reduced to ammonium by the consecutive action of nitrate and nitrite reductase. How nitrate assimilation is balanced with nitrate and nitrite efflux is unknown, as are the proteins involved. The nitrate assimilatory yeast Hansenula polymorpha was used as a model to dissect these efflux systems. We identified the sulfite transporters Ssu1 and Ssu2 as effective nitrate exporters, Ssu2 being quantitatively more important, and we characterize the Nar1 protein as a nitrate/nitrite exporter. The use of strains lacking either SSU2 or NAR1 along with the nitrate reductase gene YNR1 showed that nitrate reductase activity is not required for net nitrate uptake. Growth test experiments indicated that Ssu2 and Nar1 exporters allow yeast to cope with nitrite toxicity. We also have shown that the well-known Saccharomyces cerevisiae sulfite efflux permease Ssu1 is also able to excrete nitrite and nitrate. These results characterize for the first time essential components of the nitrate/nitrite efflux system and their impact on net nitrate uptake and its regulation. PMID:24363367

Effects of curing sodium nitrite additive and natural meat fat on growth control of Listeria monocytogenes by the bacteriocin-producing Lactobacillus curvatus strain CWBI-B28.

PubMed

Kouakou, P; Ghalfi, H; Destain, J; Dubois-Dauphin, R; Evrard, P; Thonart, P

2009-09-01

In realistic model meat systems, the separate and combined effects of fat content and sodium nitrite on the antilisterial activity of the bacteriocin of Lactobacillus curvatus CWBI-B28 were studied. In laboratory fermentations where Listeria monocytogenes was co-cultured at 4 degrees C with bacteriocin-producing CWBI-B28 in lean pork meat (fat content: 13%) without added nitrite, a strong antilisterial effect was observed after one week. The effect was maintained for an additional week, after which a slight and very gradual rebound was observed. Both added nitrite (20 ppm) and a high-fat content (43%) were found to antagonise this antilisterial effect, the Listeria cfu count reached after six weeks being 200 times as high in high-fat meat with added nitrite than in lean meat without nitrite. This antagonism could not be attributed to slower growth of the bacteriocin-producing strain, since CWBI-B28 grew optimally in fat-rich meat with 20 ppm sodium nitrite. Bacteriocin activity was also measured in the samples. The observed activity levels are discussed in relation to the degree of antilisterial protection conferred.

NITRIFICATION BY ASPERGILLUS FLAVUS1

PubMed Central

Marshall, K. C.; Alexander, M.

1962-01-01

Marshall, K. C. (Cornell University, Ithaca, N. Y.) and M. Alexander. Nitrification by Aspergillus flavus. J. Bacteriol. 83:572–578. 1962.—Aspergillus flavus has been shown to produce bound hydroxylamine, nitrite, and nitrate when grown in peptone, amino acid, or buffered ammonium media. Free hydroxylamine was not detected in these cultures, but it was found in an unbuffered ammonium medium in which neither nitrite nor nitrate was formed. Evidence was obtained for the presence of β-nitropropionic acid in the filtrate of an actively nitrifying culture. Alumina treatment of an ammonium medium prevented the formation by growing cultures of nitrite and nitrate but not bound hydroxylamine. The effect of alumina treatment was reversed by the addition of 10−3m CeCl3 to the medium. Extracts of the fungus contained peroxidase and an enzyme capable of catalyzing the production of nitrite from β-nitropropionic acid. The nitrite-forming enzyme is apparently specific for β-nitropropionate; no activity was found with nitromethane, nitroethane, and nitropropane as substrates. Nitrate was not reduced to nitrite nor was nitrite oxidized to nitrate by the hyphal extracts. The significance of these observations in nitrification by A. flavus is discussed. PMID:14470254

The impairment of learning and memory and synaptic loss in mouse after chronic nitrite exposure.

PubMed

Chen, Yongfang; Cui, Zhanjun; Wang, Lai; Liu, Hongliang; Fan, Wenjuan; Deng, Jinbo; Deng, Jiexin

2016-12-01

The objective of this study is to understand the impairment of learning and memory in mouse after chronic nitrite exposure. The animal model of nitrite exposure in mouse was created with the daily intubation of nitrite in adult healthy male mice for 3 months. Furthermore, the mouse's learning and memory abilities were tested with Morris water maze, and the expression of Synaptophysin and γ-Synuclein was visualized with immunocytochemistry and Western blot. Our results showed that nitrite exposure significantly prolonged the escape latency period (ELP) and decreased the values of the frequency across platform (FAP) as well as the accumulative time in target quadrant (ATITQ) compared to control, in dose-dependent manner. In addition, after nitrite exposure, synaptophysin (SYN) positive buttons in the visual cortex was reduced, in contrast the increase of γ-synuclein positive cells. The results above were supported by Western blot as well. We conclude that nitrite exposure could lead to a decline in mice's learning and memory. The overexpression of γ-synuclein contributed to the synaptic loss, which is most likely the cause of learning and memory impairment. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1720-1730, 2016. © 2015 Wiley Periodicals, Inc.

[Nitrates and nitrites in meat products--nitrosamines precursors].

PubMed

Avasilcăi, Liliana; Cuciureanu, Rodica

2011-01-01

To determine the content in nitrates and nitrites and the formation of two nitrosamines (N-nitrosodimethylamine--NDMA, and N-nitrosodiethylaamine--NDEA) in samples of chicken ham, dry Banat salami, dry French salami, traditional Romania sausages, and pork pastrami. Nitrites were determined by spectrophotometry with Peter-Griess reagent, and nitrates by the same method after reduction to nitrites with cadmium powder. High performance liquid chromatography with UV detection was used to determine nitrosamines. The initial concentration of nitrates, nitrites, NDMA and NDEA in the samples ranged as follows: 14.10-60.40 mg NO3/kg, 2.70-26.70 mg NO2/kg, from non-detectable to 0.90 microg NDMA/kg, and from non-detectable to 0.27 microg NDEA/kg, respectively. After 28 days the concentrations were: 3.24-17.1 mg NO3/kg, 0.04 -1.87 mg NO2/kg, 0.8-29 microg NDMA/kg, and 11.6-61.9 microg NDEA/kg, respectively. The decreased nitrate and nitrite and increased NDMA and NDEA concentrations prove that in food products nitrosamines are formed due to residual nitrite during their preservation. The determination of nitrasamines revealed levels much above the admitted maximal concentration for these food products.

Nitrate and nitrite in biology, nutrition and therapeutics

PubMed Central

Lundberg, Jon O.; Gladwin, Mark T.; Ahluwalia, Amrita; Benjamin, Nigel; Bryan, Nathan S.; Butler, Anthony; Cabrales, Pedro; Fago, Angela; Feelisch, Martin; Ford, Peter C.; Freeman, Bruce A.; Frenneau, Michael; Friedman, Joel; Kelm, Malte; Kevil, Christopher G.; Kim-Shapiro, Daniel B.; Kozlov, Andrey V.; Lancaster, Jack R.; Lefer, David J.; McColl, Kenneth; McCurry, Kenneth; Patel, Rakesh; Petersson, Joel; Rassaf, Tienush; Reutov, Valentin P.; Richter-Addo, George B.; Schechter, Alan; Shiva, Sruti; Tsuchiya, Koichiro; van Faassen, Ernst E.; Webb, Andrew J.; Zuckerbraun, Brian S.; Zweier, Jay L.; Weitzberg, Eddie

2014-01-01

Inorganic nitrate and nitrite from endogenous or dietary sources are metabolized in vivo to nitric oxide (NO) and other bioactive nitrogen oxides. The nitrate-nitrite-NO pathway is emerging as an important mediator of blood flow regulation, cell signaling, energetics and tissue responses to hypoxia. The latest advances in our understanding of the biochemistry, physiology and therapeutics of nitrate, nitrite and NO were discussed during a recent two-day meeting at the Nobel Forum, Karolinska Institutet in Stockholm. PMID:19915529

Reactive transport modeling of nitrogen in Seine River sediments

NASA Astrophysics Data System (ADS)

Akbarzadeh, Z.; Laverman, A.; Raimonet, M.; Rezanezhad, F.; Van Cappellen, P.

2016-02-01

Biogeochemical processes in sediments have a major impact on the fate and transport of nitrogen (N) in river systems. Organic matter decomposition in bottom sediments releases inorganic N species back to the stream water, while denitrification, anammox and burial of organic matter remove bioavailable N from the aquatic environment. To simulate N cycling in river sediments, a multi-component reactive transport model has been developed in MATLAB®. The model includes 3 pools of particulate organic N, plus pore water nitrate, nitrite, nitrous oxide and ammonium. Special attention is given to the production and consumption of nitrite, a N species often neglected in early diagenetic models. Although nitrite is usually considered to be short-lived, elevated nitrite concentrations have been observed in freshwater streams, raising concerns about possible toxic effects. We applied the model to sediment data sets collected at two locations in the Seine River, one upstream, the other downstream, of the largest wastewater treatment plant (WWTP) of the Paris conurbation. The model is able to reproduce the key features of the observed pore water depth profiles of the different nitrogen species. The modeling results show that the presence of oxygen in the overlying water plays a major role in controlling the exchanges of nitrite between the sediments and the stream water. In August 2012, sediments upstream of the WWTP switch from being a sink to a source of nitrite as the overlying water becomes anoxic. Downstream sediments remain a nitrite sink in oxic and anoxic conditions. Anoxic bottom waters at the upstream location promote denitrification, which produces nitrite, while at the downstream site, anammox and DNRA are important removal processes of nitrite.

The role of natural organic matter in nitrite formation by LP-UV/H2O2 treatment of nitrate-rich water.

PubMed

Semitsoglou-Tsiapou, Sofia; Mous, Astrid; Templeton, Michael R; Graham, Nigel J D; Hernández Leal, Lucía; Kruithof, Joop C

2016-12-01

The role of natural organic matter (NOM) on nitrite formation from nitrate photolysis by low pressure ultraviolet lamp (LP-UV) photolysis and LP-UV/H 2 O 2 treatment was investigated. Nitrate levels up to the WHO guideline maximum of 50 mg NO 3 - /L were used in tests. The presence of 4 mg/L Suwannee River natural organic matter (NOM) led to increased nitrite yields compared to NOM-free controls. This was caused partly by NOM scavenging of OH radicals, preserving the produced NO 2 - as well as the ONOO - that leads to NO 2 - formation, but also via the production of radical species ( 1 O 2 , O 2 - and OH) by the photolysis of NOM. In addition, solvated electrons formed by NOM photolysis may reduce nitrate directly to nitrite. For comparison, Nordic Lake NOM, representative of aquatic NOM, as well as Pony Lake NOM, which had a greater nitrogen content (6.51% w/w) than the other two types of NOM, were investigated, yielding similar nitrite levels as Suwannee River NOM. The results suggest that neither the type nor the nitrogen content of the NOM have an effect on the nitrite yields obtained over the range of UV/H 2 O 2 doses applied (UV fluences of 500-2100 mJ/cm 2 and hydrogen peroxide doses of 10, 25, and 50 mg/L). The findings indicate that for UV fluences above 1500 mJ/cm 2 the resulting nitrite concentration can exceed the 0.1 mg/L EU regulatory limit for nitrite, suggesting that nitrite formation by LP-UV advanced oxidation of nitrate-rich waters is important to consider. Copyright © 2016 Elsevier Ltd. All rights reserved.

Short-term treatment with nitrate is not sufficient to induce in vivo antithrombotic effects in rats and mice.

PubMed

Kramkowski, K; Leszczynska, A; Przyborowski, K; Proniewski, B; Marcinczyk, N; Rykaczewska, U; Jarmoc, D; Chabielska, E; Chlopicki, S

2017-01-01

In humans, short-term supplementation with nitrate is hypotensive and inhibits platelet aggregation via an nitric oxide (NO)-dependent mechanism. In the present work, we analyzed whether short-term treatment with nitrate induces antithrombotic effects in rats and mice. Arterial thrombosis was evoked electrically in a rat model in which renovascular hypertension was induced by partial ligation of the left renal artery. In mice expressing green fluorescent protein, laser-induced thrombosis was analyzed intravitally by using confocal microscope. Sodium nitrate (NaNO 3 ) or sodium nitrite (NaNO 2 ) was administered orally at a dose of 0.17 mmol/kg, twice per day for 3 days. Short-term nitrate treatment did not modify thrombus formation in either rats or mice, while nitrite administration led to pronounced antithrombotic activity. In hypertensive rats, nitrite treatment resulted in a significant decrease in thrombus weight (0.50 ± 0.08 mg vs. VEH 0.96 ± 0.09 mg; p < 0.01). In addition, nitrite inhibited ex vivo platelet aggregation and thromboxane B 2 (TxB 2 ) generation and prolonged prothrombin time. These effects were accompanied by significant increases in blood NOHb concentration and plasma nitrite concentration. In contrast, nitrate did not affect ex vivo platelet aggregation or prothrombin time and led to only slightly elevated nitrite plasma concentration. In mice, nitrate was also ineffective, while nitrite led to decreased platelet accumulation in the area of laser-induced endothelial injury. In conclusion, although nitrite induced profound NO-dependent antithrombotic effects in vivo, conversion of nitrates to nitrite in rats and mice over short-term 3-day treatment was not sufficient to elicit NO-dependent antiplatelet or antithrombotic effects.

Mechanism of nitrite oxidation by eosinophil peroxidase: implications for oxidant production and nitration by eosinophils

PubMed Central

van Dalen, Christine J.; Winterbourn, Christine C.; Kettle, Anthony J.

2005-01-01

Eosinophil peroxidase is a haem enzyme of eosinophils that is implicated in oxidative tissue injury in asthma. It uses hydrogen peroxide to oxidize thiocyanate and bromide to their respective hypohalous acids. Nitrite is also a substrate for eosinophil peroxidase. We have investigated the mechanisms by which the enzyme oxidizes nitrite. Nitrite was very effective at inhibiting hypothiocyanous acid (‘cyanosulphenic acid’) and hypobromous acid production. Spectral studies showed that nitrite reduced the enzyme to its compound II form, which is a redox intermediate containing FeIV in the haem active site. Compound II does not oxidize thiocyanate or bromide. These results demonstrate that nitrite is readily oxidized by compound I, which contains FeV at the active site. However, it reacts more slowly with compound II. The observed rate constant for reduction of compound II by nitrite was determined to be 5.6×103 M−1·s−1. Eosinophils were at least 4-fold more effective at promoting nitration of a heptapeptide than neutrophils. This result is explained by our finding that nitrite reacts 10-fold faster with compound II of eosinophil peroxidase than with the analogous redox intermediate of myeloperoxidase. Nitration by eosinophils was increased 3-fold by superoxide dismutase, which indicates that superoxide interferes with nitration. We propose that at sites of eosinophilic inflammation, low concentrations of nitrite will retard oxidant production by eosinophil peroxidase, whereas at higher concentrations nitrogen dioxide will be a major oxidant formed by these cells. The efficiency of protein nitration will be decreased by the diffusion-controlled reaction of superoxide with nitrogen dioxide. PMID:16336215

A Critical Role for the cccA Gene Product, Cytochrome c2, in Diverting Electrons from Aerobic Respiration to Denitrification in Neisseria gonorrhoeae

PubMed Central

Hopper, Amanda C.; Li, Ying

2013-01-01

Neisseria gonorrhoeae is a microaerophile that, when oxygen availability is limited, supplements aerobic respiration with a truncated denitrification pathway, nitrite reduction to nitrous oxide. We demonstrate that the cccA gene of Neisseria gonorrhoeae strain F62 (accession number NG0292) is expressed, but the product, cytochrome c2, accumulates to only low levels. Nevertheless, a cccA mutant reduced nitrite at about half the rate of the parent strain. We previously reported that cytochromes c4 and c5 transfer electrons to cytochrome oxidase cbb3 by two independent pathways and that the CcoP subunit of cytochrome oxidase cbb3 transfers electrons to nitrite. We show that mutants defective in either cytochrome c4 or c5 also reduce nitrite more slowly than the parent. By combining mutations in cccA (Δc2), cycA (Δc4), cycB (Δc5), and ccoP (ccoP-C368A), we demonstrate that cytochrome c2 is required for electron transfer from cytochrome c4 via the third heme group of CcoP to the nitrite reductase, AniA, and that cytochrome c5 transfers electrons to nitrite reductase by an independent pathway. We propose that cytochrome c2 forms a complex with cytochrome oxidase. If so, the redox state of cytochrome c2 might regulate electron transfer to nitrite or oxygen. However, our data are more consistent with a mechanism in which cytochrome c2 and the CcoQ subunit of cytochrome oxidase form alternative complexes that preferentially catalyze nitrite and oxygen reduction, respectively. Comparison with the much simpler electron transfer pathway for nitrite reduction in the meningococcus provides fascinating insights into niche adaptation within the pathogenic neisseriae. PMID:23543713

Ammonium and nitrite oxidation at nanomolar oxygen concentrations in oxygen minimum zone waters

PubMed Central

Bristow, Laura A.; Dalsgaard, Tage; Tiano, Laura; Mills, Daniel B.; Bertagnolli, Anthony D.; Wright, Jody J.; Hallam, Steven J.; Ulloa, Osvaldo; Canfield, Donald E.; Revsbech, Niels Peter; Thamdrup, Bo

2016-01-01

A major percentage of fixed nitrogen (N) loss in the oceans occurs within nitrite-rich oxygen minimum zones (OMZs) via denitrification and anammox. It remains unclear to what extent ammonium and nitrite oxidation co-occur, either supplying or competing for substrates involved in nitrogen loss in the OMZ core. Assessment of the oxygen (O2) sensitivity of these processes down to the O2 concentrations present in the OMZ core (<10 nmol⋅L−1) is therefore essential for understanding and modeling nitrogen loss in OMZs. We determined rates of ammonium and nitrite oxidation in the seasonal OMZ off Concepcion, Chile at manipulated O2 levels between 5 nmol⋅L−1 and 20 μmol⋅L−1. Rates of both processes were detectable in the low nanomolar range (5–33 nmol⋅L−1 O2), but demonstrated a strong dependence on O2 concentrations with apparent half-saturation constants (Kms) of 333 ± 130 nmol⋅L−1 O2 for ammonium oxidation and 778 ± 168 nmol⋅L−1 O2 for nitrite oxidation assuming one-component Michaelis–Menten kinetics. Nitrite oxidation rates, however, were better described with a two-component Michaelis–Menten model, indicating a high-affinity component with a Km of just a few nanomolar. As the communities of ammonium and nitrite oxidizers were similar to other OMZs, these kinetics should apply across OMZ systems. The high O2 affinities imply that ammonium and nitrite oxidation can occur within the OMZ core whenever O2 is supplied, for example, by episodic intrusions. These processes therefore compete with anammox and denitrification for ammonium and nitrite, thereby exerting an important control over nitrogen loss. PMID:27601665

Inhibition kinetics of nitritation and half-nitritation of old landfill leachate in a membrane bioreactor.

PubMed

Li, Yun; Wang, Zhaozhao; Li, Jun; Wei, Jia; Zhang, Yanzhuo; Zhao, Baihang

2017-04-01

Nitritation can be used as a pretreatment for anaerobic ammonia oxidation (anammox). Various control strategies for nitritation and half-nitritation of old landfill leachate in a membrane bioreactor were investigated in this study and the inhibition kinetics of substrate, product and old landfill leachate on nitritation were analyzed via batch tests. The results demonstrated that old landfill leachate nitritation in the membrane bioreactor can be achieved by adjusting the influent loading and dissolved oxygen (DO). From days 105-126 of the observation period, the average effluent concentration was 871.3 mg/L and the accumulation rate of [Formula: see text] was 97.2%. Half-nitritation was realized quickly by adjusting hydraulic retention time and DO. A low-DO control strategy appeared to best facilitate long-term and stable operation. Nitritation inhibition kinetic experiments showed that the inhibition of old landfill leachate was stronger than that of the substrate [Formula: see text] or product [Formula: see text] . The ammonia oxidation rate dropped by 22.2% when the concentration of old landfill leachate (calculated in chemical oxygen demand) was 1600.2 mg/L; further, when only free ammonia or free nitrous acid were used as a single inhibition factor, the ammonia oxidation rate dropped by 4.7-6.5% or 14.5-15.9%, respectively. Haldane, Aiba, and a revised inhibition kinetic model were adopted to separately fit the experimental data. The R 2 correlation coefficient values for these three models were 0.982, 0.996, and 0.992, respectively. Copyright © 2016 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Experimental and Theoretical Investigation of Effects of Ethanol and Acetic Acid on Carcinogenic NDMA Formation in Simulated Gastric Fluid.

PubMed

Zhang, Ou; Zou, Xuan; Li, Qi-Hong; Sun, Zhi; Liu, Yong Dong; Zhong, Ru Gang

2016-07-07

N-nitrosodimethylamine (NDMA), as a representative of endogenously formed N-nitroso compounds (NOCs), has become the focus of considerable research interest due to its unusually high carcinogenicity. In this study, effects of ethanol and acetic acid on the formation of NDMA from dimethylamine (DMA) and nitrite in simulated gastric fluid (SGF) were investigated. Experimental results showed that ethanol in the concentrations of 1-8% (v/v) and acetic acid in the concentrations of 0.01-8% (v/v) exhibit inhibitory and promotion effects on the formation of NDMA, respectively. Moreover, they are both in a dose-dependent manner with the largest inhibition/promotion rate reaching ∼70%. Further experimental investigations indicate that ethanol and acetic acid are both able to scavenge nitrite in SGF. It implies that there are interactions of ethanol and acetic acid with nitrite or nitrite-related nitrosating agents rather than DMA. Theoretical calculations confirm the above experimental results and demonstrate that ethanol and acetic acid can both react with nitrite-related nitrosating agents to produce ethyl nitrite (EtONO) and acetyl nitrite (AcONO), respectively. Furthermore, the reactivities of ethyl nitrite, acetyl nitrite, and dinitrogen trioxide reacting with DMA were found in the order of AcONO > N2O3 ≫ EtONO. This is probably the main reason why there are completely different effects of ethanol and acetic acid on NDMA formation. On the basis of the above results, two requirements for a potential inhibitor of NOCs formation in SGF were provided. The results obtained in this study will be helpful in better understanding the inhibition/promotion mechanisms of compounds on NDMA formation in SGF and searching for protective substances to prevent carcinogenic NOCs formation.

Nitrogen isotope effects induced by anammox bacteria

PubMed Central

Brunner, Benjamin; Contreras, Sergio; Lehmann, Moritz F.; Matantseva, Olga; Rollog, Mark; Kalvelage, Tim; Klockgether, Gabriele; Lavik, Gaute; Jetten, Mike S. M.; Kartal, Boran; Kuypers, Marcel M. M.

2013-01-01

Nitrogen (N) isotope ratios (15N/14N) provide integrative constraints on the N inventory of the modern ocean. Anaerobic ammonium oxidation (anammox), which converts ammonium and nitrite to dinitrogen gas (N2) and nitrate, is an important fixed N sink in marine ecosystems. We studied the so far unknown N isotope effects of anammox in batch culture experiments. Anammox preferentially removes 14N from the ammonium pool with an isotope effect of +23.5‰ to +29.1‰, depending on factors controlling reversibility. The N isotope effects during the conversion of nitrite to N2 and nitrate are (i) inverse kinetic N isotope fractionation associated with the oxidation of nitrite to nitrate (−31.1 ± 3.9‰), (ii) normal kinetic N isotope fractionation during the reduction of nitrite to N2 (+16.0 ± 4.5‰), and (iii) an equilibrium N isotope effect between nitrate and nitrite (−60.5 ± 1.0‰), induced when anammox is exposed to environmental stress, leading to the superposition of N isotope exchange effects upon kinetic N isotope fractionation. Our findings indicate that anammox may be responsible for the unresolved large N isotope offsets between nitrate and nitrite in oceanic oxygen minimum zones. Irrespective of the extent of N isotope exchange between nitrate and nitrite, N removed from the combined nitrite and nitrate (NOx) pool is depleted in 15N relative to NOx. This net N isotope effect by anammox is superimposed on the N isotope fractionation by the co-occurring reduction of nitrate to nitrite in suboxic waters, possibly enhancing the overall N isotope effect for N loss from oxygen minimum zones. PMID:24191043

Nitrosamines in bacon: a case study of balancing risks.

PubMed Central

McCutcheon, J W

1984-01-01

Nitrite has been used for centuries to preserve, color, and flavor meat. Today, about 10 billion pounds of cured meat products are produced annually, accounting for some one-tenth of the American food supply. Regulators became concerned about the safety of using nitrite in the early 1960s when studies showed the presence of carcinogenic nitrosamines in cured meat products. In the early 1970s, a study at the Massachusetts Institute of Technology implicated nitrite itself as a carcinogen. As studies have raised concern over the safety of nitrite, regulators have had to weigh the potential risk from cancer against nitrite's proven role in protecting consumers from deadly food poisoning bacteria. Today there is little scientific support for the theory that nitrite is a direct carcinogen. To deal with the nitrosamine problem, the U.S. Department of Agriculture (USDA) lowered the permissible amount of nitrite in cured meats to that level considered necessary for botulism protection. Regulators, however, found it necessary to take additional steps with bacon because nitrosamines were found consistently in fried bacon samples. In addition to lowering the amount of nitrite that could be added to "pumped bacon" (cured by injecting liquid curing agents in the pork belly), USDA required the addition of nitrosamine inhibitors and began an intensive monitoring program in processing plants to ensure that fried bacon did not contain confirmable nitrosamines. The cooperative effort between Government and industry resulted in the virtual elimination of confirmable nitrosamines in pumped bacon by 1980. USDA is continuing its efforts to reduce nitrite in meats wherever possible. It is involved in active research programs in the Federal Government, academia, and industry. PMID:6431483

Assimilation of Nitrogen from Nitrite and Trinitrotoluene in Pseudomonas putida JLR11

PubMed Central

Caballero, Antonio; Esteve-Núñez, Abraham; Zylstra, Gerben J.; Ramos, Juan L.

2005-01-01

Pseudomonas putida JLR11 releases nitrogen from the 2,4,6-trinitrotoluene (TNT) ring as nitrite or ammonium. These processes can occur simultaneously, as shown by the observation that a nasB mutant impaired in the reduction of nitrite to ammonium grew at a slower rate than the parental strain. Nitrogen from TNT is assimilated via the glutamine syntethase-glutamate synthase (GS-GOGAT) pathway, as evidenced by the inability of GOGAT mutants to use TNT. This pathway is also used to assimilate ammonium from reduced nitrate and nitrite. Three mutants that had insertions in ntrC, nasT, and cnmA, which encode regulatory proteins, failed to grow on nitrite but grew on TNT, although slower than the wild type. PMID:15601726

Design, synthesis and biological assessment of N-adamantyl, substituted adamantyl and noradamantyl phthalimidines for nitrite, TNF-α and angiogenesis inhibitory activities.

PubMed

Luo, Weiming; Tweedie, David; Beedie, Shaunna L; Vargesson, Neil; Figg, William D; Greig, Nigel H; Scerba, Michael T

2018-05-01

A library of 15 novel and heretofore uncharacterized adamantyl and noradamantyl phthalimidines was synthesized and evaluated for neuroprotective and anti-angiogenic properties. Phthalimidine treatment in LPS-challenged cells effected reductions in levels of secreted TNF-α and nitrite relative to basal amounts. The primary SAR suggests nitration of adamantyl phthalimidines has marginal effect on TNF-α activity but promotes anti-nitrite activity; thioamide congeners retain anti-nitrite activity but are less effective reducing TNF-α. Site-specific nitration and thioamidation provided phthalimidine 24, effecting an 88.5% drop in nitrite concurrent with only a 4% drop in TNF-α. Notable anti-angiogenesis activity was observed for 20, 21 and 22. Published by Elsevier Ltd.

Oxidation phenomena and color properties of grape pomace on nitrite-reduced meat emulsion systems.

PubMed

Riazi, Fatemeh; Zeynali, Fariba; Hoseini, Ebrahim; Behmadi, Homa; Savadkoohi, Sobhan

2016-11-01

The present study focuses on the effect of different levels of red grape pomace (1 and 2%, w/w) on the color changes, lipid oxidation (TBARS), antioxidant activity, microbial counts, total phenol content and sensory attributes of the sausages formulated with various levels of sodium nitrite (30, 60 and 120mg/kg). It was found that the addition of grape pomace (1%, w/w) in combination of reduced nitrite levels to the beef sausage samples reduced TBARS content and the degree of lipid oxidation. Antioxidant activity and total phenol contents were further evaluated based on DPPH scavenging activity method. A significant reduction in lightness (L*) and yellowness (b*) of systems containing grape pomace was observed, following by an increase in the oxidative stability and the radical scavenging activity. Acceptability of beef sausages was not significantly (P>0.05) affected by the addition of grape pomace and had relatively greater scores from a sensory point of view. Copyright © 2016 Elsevier Ltd. All rights reserved.

Electrochemical detection of nitrite on poly(pyronin Y)/graphene nanocomposites modified ITO substrate

NASA Astrophysics Data System (ADS)

Şinoforoğlu, Mehmet; Dağcı, Kader; Alanyalıoğlu, Murat; Meral, Kadem

2016-06-01

The present study reports on an easy preparation of poly(pyronin Y)/graphene (poly(PyY)/graphene) nanocomposites thin films on indium tin oxide coated glass substrates (ITO). The thin films of poly(PyY)/graphene nanocomposites are prepared by a novel method consisting of three steps; (i) preparation of graphene oxide (GO) thin films on ITO by spin-coating method, (ii) self-assembly of PyY molecules from aqueous solution onto the GO thin film, (iii) surface-confined electropolymerization (SCEP) of the adsorbed PyY molecules on the GO thin film. The as-prepared poly(PyY)/graphene nanocomposites thin films are characterized by using electroanalytical and spectroscopic techniques. Afterwards, the graphene-based polymeric dye thin film on ITO is used as an electrode in an electrochemical cell. Its performance is tested for electrochemical detection of nitrite. Under optimized conditions, the electrocatalytical effect of the nanocomposites thin film through electrochemical oxidation of nitrite is better than that of GO coated ITO.

Toluene nitration in irradiated nitric acid and nitrite solutions

NASA Astrophysics Data System (ADS)

Elias, Gracy; Mincher, Bruce J.; Mezyk, Stephen P.; Muller, Jim; Martin, Leigh R.

2011-04-01

The kinetics, mechanisms, and stable products produced for the nitration of aryl alkyl mild ortho-para director toluene in irradiated nitric acid and neutral nitrite solutions were investigated using γ and pulse radiolysis. Electron pulse radiolysis was used to determine the bimolecular rate constants for the reaction of toluene with different transient species produced by irradiation. HPLC with UV detection, GC-MS and LC-MS, were used to assess the stable reaction products. Free-radical based nitration reaction products were found in irradiated acidic and neutral media. In 6.0 M HNO3, ring substitution, side chain substitution, and oxidation, produced different nitrated toluene products. For ring substitution, nitrogen oxide radicals were added mainly to cyclohexadienyl radicals, whereas for side chain substitution, these radicals were added to the carbon-centered benzyl radical produced by H-atom abstraction. In neutral nitrite solutions, radiolytically-induced ring nitration products approached a statistically random distribution, suggesting a direct free-radical reaction involving addition of the rad NO2 radical.

Achieving nitritation in a continuous moving bed biofilm reactor at different temperatures through ratio control.

PubMed

Bian, Wei; Zhang, Shuyan; Zhang, Yanzhuo; Li, Wenjing; Kan, Ruizhe; Wang, Wenxiao; Zheng, Zhaoming; Li, Jun

2017-02-01

A ratio control strategy was implemented in a continuous moving bed biofilm reactor (MBBR) to investigate the response to different temperatures. The control strategy was designed to maintain a constant ratio between dissolved oxygen (DO) and total ammonia nitrogen (TAN) concentrations. The results revealed that a stable nitritation in a biofilm reactor could be achieved via ratio control, which compensated the negative influence of low temperatures by stronger oxygen-limiting conditions. Even with a temperature as low as 6°C, stable nitritation could be achieved when the controlling ratio did not exceed 0.17. Oxygen-limiting conditions in the biofilm reactor were determined by the DO/TAN concentrations ratio, instead of the mere DO concentration. This ratio control strategy allowed the achievement of stable nitritation without complete wash-out of NOB from the reactor. Through the ratio control strategy full nitritation of sidestream wastewater was allowed; however, for mainstream wastewater, only partial nitritation was recommended. Copyright © 2016 Elsevier Ltd. All rights reserved.

Use of natural antimicrobials to improve the control of Listeria monocytogenes in a cured cooked meat model system.

PubMed

Xi, Y; Sullivan, G A; Jackson, A L; Zhou, G H; Sebranek, J G

2011-07-01

Concern about nitrite in processed meats has increased consumer demand for natural products manufactured without nitrite or nitrate. Studies on commercial meat products labeled as "Uncured" and "No-Nitrite-or-Nitrate-Added" have shown less control of nitrite in these products and greater potential growth of bacterial pathogens. To improve the safety of the "naturally cured" meats, several natural ingredients were studied in a cured cooked meat model system (80:20 pork, 10% water, 2% salt, and 150 or 50 ppm ingoing sodium nitrite) that closely resembled commercial frankfurters to determine their inhibitory effect on Listeria monocytogenes. Results showed that cranberry powder at 1%, 2% and 3% resulted in 2-4 log cfu/g less growth of L. monocytogenes compared to the control with nitrite alone (P<0.05). Other natural compounds, such as cherry powder, lime powder and grape seed extract, also provided measureable inhibition to L. monocytogenes when combined with cranberry powder (P<0.05). Copyright © 2011 Elsevier Ltd. All rights reserved.

The use of atmospheric pressure plasma as a curing process for canned ground ham.

PubMed

Lee, Juri; Jo, Kyung; Lim, Yubong; Jeon, Hee Joon; Choe, Jun Ho; Jo, Cheorun; Jung, Samooel

2018-02-01

This study investigated the potential use of atmospheric pressure plasma (APP) treatment as a curing process for canned ground ham. APP treatment for 60min while mixing increased the nitrite content in the meat batters from 0.64 to 60.50mgkg -1 while the pH and the total content of aerobic bacteria in the meat batters were unchanged. The canned ground hams cured by the APP treatment for 30min displayed no difference in their physicochemical qualities, such as nitrosyl hemochrome, color, residual nitrite, texture, lipid oxidation, and protein oxidation, compared with those of canned ground hams cured with sodium nitrite or celery powder at 42mgkg -1 of nitrite. The canned ground hams cured by the APP treatment received a higher score in taste and overall acceptability than those cured with sodium nitrite. Canned ground ham can be cured by the APP treatment without nitrite additives. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of processing variables on the outgrowth of Clostridium sporogenes PA 3679 spores in comminuted meat cured with sorbic acid and sodium nitrite.

PubMed Central

Robach, M C

1979-01-01

The effects of the initial pH and a "short pump" on the outgrowth of Clostridium sporogenes PA 3679 spores in comminuted cured pork were studied. Fresh ground pork was cured with salt, sugar, phosphate, ascorbate, and varying amounts of sodium nitrite and sorbic acid. The product was comminuted and inoculated with 1,000 spores of C. sporogenes per g. The meat was stuffed into 1-ounce (ca. 28.4-g) aluminum tubes, cooked to 58.5 degrees C, cooled, and incubated at 27 degrees C to observe for swells. Product cured with 0.2% sorbic acid in combination with 40 ppm sodium nitrite (40 microgram/g) had better clostridium inhibition than did product cured with 120 ppm nitrite within a pH range of 5.0 to 6.7. The sorbic acid-40 ppm nitrite combination also gave better clostridial protection than did the 120 ppm nitrite alone when reduced amounts of curing ingredients were present. PMID:44445

Effect of processing variables on the outgrowth of Clostridium sporogenes PA 3679 spores in comminuted meat cured with sorbic acid and sodium nitrite.

PubMed

Robach, M C

1979-11-01

The effects of the initial pH and a "short pump" on the outgrowth of Clostridium sporogenes PA 3679 spores in comminuted cured pork were studied. Fresh ground pork was cured with salt, sugar, phosphate, ascorbate, and varying amounts of sodium nitrite and sorbic acid. The product was comminuted and inoculated with 1,000 spores of C. sporogenes per g. The meat was stuffed into 1-ounce (ca. 28.4-g) aluminum tubes, cooked to 58.5 degrees C, cooled, and incubated at 27 degrees C to observe for swells. Product cured with 0.2% sorbic acid in combination with 40 ppm sodium nitrite (40 microgram/g) had better clostridium inhibition than did product cured with 120 ppm nitrite within a pH range of 5.0 to 6.7. The sorbic acid-40 ppm nitrite combination also gave better clostridial protection than did the 120 ppm nitrite alone when reduced amounts of curing ingredients were present.

Dietary nitrate and nitrite: Benefits, risks, and evolving perceptions.

PubMed

Bedale, Wendy; Sindelar, Jeffrey J; Milkowski, Andrew L

2016-10-01

Consumers have an illogical relationship with nitrite (and its precursor, nitrate) in food. Despite a long history of use, nitrite was nearly banned from use in foods in the 1970s due to health concerns related to the potential for carcinogenic nitrosamine formation. Changes in meat processing methods reduced those potential risks, and nitrite continued to be used in foods. Since then, two opposing movements continue to shape how consumers view dietary nitrate and nitrite. The discovery of the profound physiological importance of nitric oxide led to the realization that dietary nitrate contributes significantly to the nitrogen reservoir for nitric oxide formation. Numerous clinical studies have also demonstrated beneficial effects from dietary nitrate consumption, especially in vascular and metabolic health. However, the latest wave of consumer sentiment against food additives, the clean-label movement, has renewed consumer fear and avoidance of preservatives, including nitrite. Education is necessary but may not be sufficient to resolve this disconnect in consumer perception. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of sodium ascorbate and sodium nitrite on protein and lipid oxidation in dry fermented sausages.

PubMed

Berardo, A; De Maere, H; Stavropoulou, D A; Rysman, T; Leroy, F; De Smet, S

2016-11-01

The effects of sodium nitrite and ascorbate on lipid and protein oxidation were studied during the ripening process of dry fermented sausages. Samples were taken at day 0, 2, 8, 14, 21 and 28 of ripening to assess lipid (malondialdehyde) and protein (carbonyls and sulfhydryl groups) oxidation. Sodium ascorbate and nitrite were separately able to reduce the formation of malondialdehyde. Their combined addition resulted in higher amounts of carbonyl compounds compared to their separate addition or the treatment without any of both compounds. Moreover, sodium nitrite limited the formation of γ-glutamic semialdehyde whereas sodium ascorbate showed a pro-oxidant effect. A loss of thiol groups was observed during ripening, which was not affected by the use of sodium ascorbate nor sodium nitrite. In conclusion, sodium nitrite and ascorbate affected protein and lipid oxidation in different manners. The possible pro-oxidant effect of their combined addition on carbonyl formation might influence the technological and sensory properties of these products. Copyright © 2016 Elsevier Ltd. All rights reserved.

Dog rose (Rosa canina L.) as a functional ingredient in porcine frankfurters without added sodium ascorbate and sodium nitrite.

PubMed

Vossen, Els; Utrera, Mariana; De Smet, Stefaan; Morcuende, David; Estévez, Mario

2012-12-01

The effect of dog rose (Rosa canina L.; RC), rich in polyphenols and ascorbic acid, on lipid and protein oxidation, colour stability and texture of frankfurters was investigated. Four treatments were prepared: with 5 or 30 g/kg RC extract and without sodium ascorbate and sodium nitrite (5RC and 30RC, respectively), a positive control (with sodium ascorbate and sodium nitrite; PC) and a negative control (without sodium ascorbate, sodium nitrite or RC extract; NC). Hexanal values were much higher throughout storage in NC compared to RC and PC frankfurters (P<0.001). The RC extracts protected against protein oxidation, but not as efficiently as PC (P<0.05). In the RC treated frankfurters, lower a* values were measured compared to PC due to the lack of sodium nitrite. In conclusion, dog rose can act as a natural antioxidant in frankfurters, but not as full replacer for sodium nitrite. Copyright © 2012 Elsevier Ltd. All rights reserved.

Nitrite Contents in Fresh Vegetables of Different Families and Genus

NASA Astrophysics Data System (ADS)

Cui, Yuqian; Li, Xiao; Xu, Lingyi; Pang, Meixia; Qi, Jinghua; Wang, Fang

2017-12-01

The aim of this study is firstly aimed at investigating the contents of nitrite in common consumed vegetables according to families and genus classification. The vegetables were randomly collected and analyzed in quartile sampling according to GB5009.30-2016. The vegetables were analyzed by the software of Spss20.0 and statistically significant Duncan multiple comparisons. The data indicates that the nitrite contents in different families and different genus vegetables in same family were significant (P<0.01). A relatively high nitrite concentration was observed in Chenopodiaceae which is 0.5920mg/kg dry weight. A relatively low nitrite concentration was observed in Dioscoreaceae that contentration is 0.0032mg/kg dry weight. The nitrite contents of different genus are large, in which the relatively high concentration samples were red beet root (0.886mg/kg dry weight), peanut (0.7485mg/kg dry weight), corn kernels (0.7119mg/kg dry weight), Lotus root (0.592mg/kg dry weight).

Nitrate and nitrite ingestion and risk of ovarian cancer among postmenopausal women in Iowa

PubMed Central

Inoue-Choi, Maki; Jones, Rena R.; Anderson, Kristin E.; Cantor, Kenneth P.; Cerhan, James R.; Krasner, Stuart; Robien, Kim; Weyer, Peter J.; Ward, Mary H.

2014-01-01

Nitrate and nitrite are precursors in the endogenous formation of N-nitroso compounds (NOC), potential human carcinogens. We evaluated the association of nitrate and nitrite ingestion with postmenopausal ovarian cancer risk in the Iowa Women’s Health Study. Among 28,555 postmenopausal women, we identified 315 incident epithelial ovarian cancers from 1986 to 2010. Dietary nitrate and nitrite intakes were assessed at baseline using food frequency questionnaire data. Drinking water source at home was obtained in a 1989 follow-up survey. Nitrate-nitrogen (NO3-N) and total trihalomethane (TTHM) levels for Iowa public water utilities were linked to residences and average levels were computed based on each woman’s duration at the residence. We computed multivariable-adjusted hazard ratios (HR) and 95% confidence intervals (CI) using Cox proportional hazards regression. We tested interactions of nitrate with TTHMs and dietary factors known to influence NOC formation. Ovarian cancer risk was 2.03 times higher (CI=1.22–3.38, ptrend=0.003) in the highest quartile (≥2.98 mg/L) compared with the lowest quartile (≤0.47 mg/L; reference) of NO3-N in public water, regardless of TTHM levels. Risk among private well users was also elevated (HR=1.53, CI=0.93–2.54) compared with the same reference group. Associations were stronger when vitamin C intake was

In Situ Detection of Macronutrients and Chloride in Seawater by Submersible Electrochemical Sensors.

PubMed

Cuartero, Maria; Crespo, Gaston; Cherubini, Thomas; Pankratova, Nadezda; Confalonieri, Fabio; Massa, Francesco; Tercier-Waeber, Mary-Lou; Abdou, Melina; Schäfer, Jörg; Bakker, Eric

2018-04-03

A new submersible probe for the in situ detection of nitrate, nitrite, and chloride in seawater is presented. Inline coupling of a desalination unit, an acidification unit, and a sensing flow cell containing all-solid-state membrane electrodes allows for the potentiometric detection of nitrate and nitrite after removal of the key interfering ions in seawater, chloride and hydroxide. Thus, the electrodes exhibited attractive analytical performances for the potentiometric detection of nitrate and nitrite in desalinated and acidified seawater: fast response time ( t 95 < 12 s), excellent stability (long-term drifts of <0.5 mV h -1 ), good reproducibility (calibration parameter deviation of <3%), and satisfactory accuracy (uncertainties <8%Diff compared to reference technique). The desalination cell, which can be repetitively used for about 30 times, may additionally be used as an exhaustive, and therefore calibration-free, electrochemical sensor for chloride and indirect salinity detection. The detection of these two parameters together with nitrate and nitrite may be useful for the correlation of relative changes in macronutrient levels with salinity cycles, which is of special interest in recessed coastal water bodies. The system is capable of autonomous operation during deployment, with routines for repetitive measurements (every 2 h), data storage and management, and computer visualization of the data in real time. In situ temporal profiles observed in the Arcachon Bay (France) showed valuable environmental information concerning tide-dependent cycles of nitrate and chloride levels in the lagoon, which are here observed for the first time using direct in situ measurements. The submersible probe based on membrane electrodes presented herein may facilitate the study of biogeochemical processes occurring in marine ecosystems by the direct monitoring of nitrate and nitrite levels, which are key chemical targets in coastal waters.

Metabolite toxicity determines the pace of molecular evolution within microbial populations.

PubMed

Lilja, Elin E; Johnson, David R

2017-02-14

The production of toxic metabolites has shaped the spatial and temporal arrangement of metabolic processes within microbial cells. While diverse solutions to mitigate metabolite toxicity have evolved, less is known about how evolution itself is affected by metabolite toxicity. We hypothesized that the pace of molecular evolution should increase as metabolite toxicity increases. At least two mechanisms could cause this. First, metabolite toxicity could increase the mutation rate. Second, metabolite toxicity could increase the number of available mutations with large beneficial effects that selection could act upon (e.g., mutations that provide tolerance to toxicity), which consequently would increase the rate at which those mutations increase in frequency. We tested this hypothesis by experimentally evolving the bacterium Pseudomonas stutzeri under denitrifying conditions. The metabolite nitrite accumulates during denitrification and has pH-dependent toxic effects, which allowed us to evolve P. stutzeri at different magnitudes of nitrite toxicity. We demonstrate that increased nitrite toxicity results in an increased pace of molecular evolution. We further demonstrate that this increase is generally due to an increased number of available mutations with large beneficial effects and not to an increased mutation rate. Our results demonstrate that the production of toxic metabolites can have important impacts on the evolutionary processes of microbial cells. Given the ubiquity of toxic metabolites, they could also have implications for understanding the evolutionary histories of biological organisms.

Nitrite therapy after cardiac arrest reduces ROS generation, improves cardiac and neurological function and enhances survival via reversible inhibition of mitochondrial complex I

PubMed Central

Dezfulian, Cameron; Shiva, Sruti; Alekseyenko, Aleksey; Pendyal, Akshay; Beiser, DG; Munasinghe, Jeeva P.; Anderson, Stasia A.; Chesley, Christopher F.; Hoek, TL Vanden; Gladwin, Mark T.

2009-01-01

Background Three-fourths of cardiac arrest survivors die prior to hospital discharge or suffer significant neurological injury. Excepting therapeutic hypothermia and revascularization, no novel therapies have been developed that improve survival or cardiac and neurological function after resuscitation. Nitrite (NO2−) increases cellular resilience to focal ischemia-reperfusion injury in multiple organs. We hypothesized that nitrite therapy may improve outcomes after the unique global ischemia-reperfusion insult of cardiopulmonary arrest. Methods and Results We developed a mouse model of cardiac arrest characterized by 12-minutes of normothermic asystole and a high cardiopulmonary resuscitation (CPR) rate. In this model, global ischemia and CPR was associated with blood and organ nitrite depletion, reversible myocardial dysfunction, impaired alveolar gas exchange, neurological injury and an approximate 50% mortality. A single low dose of intravenous nitrite (50 nmol=1.85 μmol/kg=0.13 mg/kg) compared to blinded saline placebo given at CPR initiation with epinephrine improved cardiac function, survival and neurological outcomes. From a mechanistic standpoint, nitrite treatment restored intracardiac nitrite and increased S-nitrosothiol levels, decreased pathological cardiac mitochondrial oxygen consumption due to reactive oxygen species formation and prevented oxidative enzymatic injury via reversible specific inhibition of respiratory chain complex I. Conclusion Nitrite therapy after resuscitation from 12-minutes of asystole rapidly and reversibly modulated mitochondrial reactive oxygen species generation during early reperfusion, limiting acute cardiac dysfunction and death, as well as neurological impairment in survivors. PMID:19704094

Nitrite reduction by biogenic hydroxycarbonate green rusts: evidence for hydroxy-nitrite green rust formation as an intermediate reaction product.

PubMed

Guerbois, Delphine; Ona-Nguema, Georges; Morin, Guillaume; Abdelmoula, Mustapha; Laverman, Anniet M; Mouchel, Jean-Marie; Barthelemy, Kevin; Maillot, Fabien; Brest, Jessica

2014-04-15

The present study investigates for the first time the reduction of nitrite by biogenic hydroxycarbonate green rusts, bio-GR(CO3), produced from the bioreduction of ferric oxyhydroxycarbonate (Fohc), a poorly crystalline solid phase, and of lepidocrocite, a well-crystallized Fe(III)-oxyhydroxide mineral. Results show a fast Fe(II) production from Fohc, which leads to the precipitation of bio-GR(CO3) particles that were roughly 2-fold smaller (2.3 ± 0.4 μm) than those obtained from the bioreduction of lepidocrocite (5.0 ± 0.4 μm). The study reveals that both bio-GR(CO3) are capable of reducing nitrite ions into gaseous nitrogen species such as NO, N2O, or N2 without ammonium production at neutral initial pH and that nitrite reduction proceeded to a larger extent with smaller particles than with larger ones. On the basis of the identification of intermediates and end-reaction products using X-ray diffraction and X-ray absorption fine structure (XAFS) spectroscopy at the Fe K-edge, our study shows the formation of hydroxy-nitrite green rust, GR(NO2), a new type of green rust 1, and suggests that the reduction of nitrite by biogenic GR(CO3) involves both external and internal reaction sites and that such a mechanism could explain the higher reactivity of green rust with respect to nitrite, compared to other mineral substrates possessing only external reactive sites.

Nigella sativa oil attenuates chronic nephrotoxicity induced by oral sodium nitrite: Effects on tissue fibrosis and apoptosis.

PubMed

Al-Gayyar, Mohammed M H; Hassan, Hanan M; Alyoussef, Abdullah; Abbas, Ahmed; Darweish, Mohamed M; El-Hawwary, Amany A

2016-03-01

Sodium nitrite, a food preservative, has been reported to increase oxidative stress indicators such as lipid peroxidation, which can affect different organs including the kidney. Here, we investigated the toxic effects of oral sodium nitrite on kidney function in rats and evaluated potential protective effects of Nigella sativa oil (NSO). Seventy adult male Sprague-Dawley rats received 80 mg/kg sodium nitrite orally in the presence or absence of NSO (2.5, 5, and 10 ml/kg) for 12 weeks. Morphological changes were assessed by hematoxylin and eosin, Mallory trichome, and periodic acid-Schiff staining. Renal tissues were used for measurements of oxidative stress markers, C-reactive protein, cytochrome C oxidase, transforming growth factor (TGF)-beta1, monocyte chemotactic protein (MCP)-1, pJNK/JNK, and caspase-3. NSO significantly reduced sodium nitrite-induced elevation in serum urea and creatinine, as well as increasing normal appearance of renal tissue. NSO also prevented reductions in glycogen levels caused by sodium nitrite alone. Moreover, NSO treatment resulted in dose-dependent significant reductions in fibrosis markers after sodium nitrite-induced 3- and 2.7-fold increase in MCP-1 and TGF-beta1, respectively. Finally, NSO partially reduced the elevated caspase-3 and pJNK/JNK. NSO ameliorates sodium nitrite-induced nephrotoxicity through blocking oxidative stress, attenuation of fibrosis/inflammation, restoration of glycogen level, amelioration of cytochrome C oxidase, and inhibition of apoptosis.

In vitro effect of sodium nitrite on platelet aggregation in human platelet rich plasma--preliminary report.

PubMed

Kadan, M; Doğanci, S; Yildirim, V; Özgür, G; Erol, G; Karabacak, K; Avcu, F

2015-10-01

The role of nitrates and nitric oxide on platelet functions has obtained an increasing attention with respect to their potential effects on cardiovascular disorders. In this study we aimed to analyze the effect of sodium nitrite on platelet functions in human platelets. This in vitro study was designed to show the effect of sodium nitrite on platelet functions in seven healthy volunteers. Blood samples were centrifuged to prepare platelet rich plasma and platelet poor plasma. Platelet rich plasma was diluted with the platelet poor plasma to have a final count of 300,000 ± 25,000 platelets. Platelet rich plasma was incubated with six different increasing doses (from 10 μM to 5 mM) of sodium nitrite for 1 hour at 37°C. Then stimulating agents including collagen (3 μg ml-1), adenosine diphosphate (10 μM), and epinephrine (10 μM) were added to the cuvette. Changes in light transmission were observed for 10 minutes. In addition spontaneous aggregation were performed in control group with all aggregating agents separately. Effect of sodium nitrite on agonist-induced platelet aggregation depends on the concentration of sodium nitrite. Compared with control group, agonist-induced platelet aggregations were significantly suppressed by sodium nitrite at the concentration of 5, 1.0 and 0.5 mM. Our results suggested that sodium nitrite has inhibitory effects in vitro on platelet aggregation in a dose-dependent manner.

Effects of agriculture production systems on nitrate and nitrite accumulation on baby-leaf salads

PubMed Central

Aires, Alfredo; Carvalho, Rosa; Rosa, Eduardo A S; Saavedra, Maria J

2013-01-01

Nitrate and nitrite are widespread contaminants of vegetables, fruits, and waters. The levels of these compounds are increased as a result of using organic wastes from chemical industries, domestic wastes, effluents, nitrogenous fertilizers, and herbicides in agriculture. Therefore, determining the nitrate and nitrite levels in biological, food, and environmental samples is important to protect human health and the environment. In this context, we set this study, in which we report the effect of production system (conventional and organic) on the accumulation of nitrates and nitrites in fresh baby-leaf samples. The average levels of the nitrate () and nitrite () contents in six different baby-leaf salads of a single species (green lettuce, red lettuce, watercress, rucola, chard, and corn salad) produced in organic and conventional agriculture system were evaluated. Spectrophotometric analytical method recently published was validated and used. Nitrates and nitrites were detected in all samples. The nitrates levels from organic production varied between 1.45 and 6.40 mg/kg fresh weight (FW), whereas those from conventional production ranged from 10.5 to 45.19 mg/kg FW. The nitrites content was lower than nitrates and ranged from 0.32 to 1.89 mg/kg FW in organic production system and between 0.14 and 1.41 mg/kg FW in conventional production system. Our results showed that the nitrate content was dependent on the agricultural production system, while for nitrites, this dependency was less pronounced. PMID:24804008

Genotoxicity testing of cooked cured meat pigment (CCMP) and meat emulsion coagulates prepared with CCMP.

PubMed

Stevanović, M; Cadez, P; Zlender, B; Filipic, M

2000-07-01

The preformed cooked cured meat pigment (CCMP) synthesized directly from bovine red blood cells or through a hemin intermediate was found to be a viable colorant for application to comminuted pork as a nitrite substitute. However the genotoxicity of CCMP and meat emulsion coagulates prepared with CCMP has not been evaluated. Therefore the objectives of this work were to investigate genotoxicity of CCMP and the influence of CCMP addition on genotoxicity and the content of residual nitrite in model meat emulsion coagulates. Meat emulsions were prepared from white (musculus longissimus dorsi) and red (musculus quadriceps femoris) pork muscles with two different amounts of synthesized pigment CCMP. Comparatively, emulsions with fixed addition of nitrite salt and emulsions without any addition for color development were made. Genotoxicity of CCMP and meat emulsion coagulates was tested with the SOS/umu test and the Ames test. Neither CCMP nor meat emulsion coagulates prepared with CCMP or nitrite salt were genotoxic in the SOS/umu test. In the Ames test using Salmonella Typhimurium strains TA98 and TA100 samples of coagulates prepared with CCMP and with nitrite showed weak mutagenic activity in Salmonella Typhimurium strain TA100 but only in the absence of the metabolic activation, while CCMP was not mutagenic. Coagulates prepared with CCMP contained significantly less residual nitrite than coagulates prepared with nitrite salt. These results indicate that from the human health standpoint the substitution of nitrite salt with CCMP would be highly recommendable.

The Interaction of Nitrites with Food, Drugs, and Contaminants.

ERIC Educational Resources Information Center

Greenland, Sander

1978-01-01

Nitrites commonly occur in food and drinking water as additives, contaminants, or products of biological processes. These highly reactive substances combine with other commonly ingested substances to form potent carcinogens. Controls are needed on levels of nitrites and reactive contaminants in food and drinking water. (RE)

Effects of nitrite stress on mRNA expression of antioxidant enzymes, immune-related genes and apoptosis-related proteins in Marsupenaeus japonicus.

PubMed

Zheng, Jinbin; Mao, Yong; Su, Yongquan; Wang, Jun

2016-11-01

Nitrite accumulation in aquaculture systems is a potential risk factor that may trigger stress responses in aquatic organisms. However, the mechanisms regulating the responses of shrimp to nitrite stress remain unclear. In this study, full-length cDNA sequences of two apoptosis-related genes, caspase-3 and defender against apoptotic death (DAD-1), were cloned from Marsupenaeus japonicus for the first time, and their expression levels and tissue distribution were analyzed by quantitative real-time PCR (qRT-PCR). The full lengths of Mjcaspase-3 and MjDAD-1 were 1203 bp and 640 bp respectively, with deduced amino acid (AA) sequences of 321 and 114 AA. Mjcaspase-3 was predominantly expressed in haemocytes and weakly expressed in the seven other tissues tested. MjDAD-1 was mainly expressed in the defense and digestive tissues, especially in the hepatopancreas and hemocytes. To explore the influence of nitrite stress on the genetic response of antioxidant enzymes, immune-related genes and apoptosis-related proteins, the mRNA expression profiles of MjCAT, MjMnSOD, Mj-ilys, Mj-sty, Mjcaspase-3 and MjDAD-1 in response to nitrite stress were analyzed by qRT-PCR. The mRNA levels of MjCAT, MjMnSOD, Mj-ilys, Mj-sty, Mjcaspase-3 and MjDAD-1 show both time- and dose-dependent changes in response to nitrite stress. The mRNA expression levels of MjCAT and MjSOD peaked at 6 h for all nitrite concentrations tested (p < 0.05) and the up-regulated of MjCAT and MjSOD exhibited a positive correlation with the nitrite concentration. The mRNA expression levels of Mj-ilys and Mj-sty gradually decreased during the experiment period. Mjcaspase-3 mRNA level reached a maximum at 6 h (p < 0.05), and MjDAD-1 reached its peak at 12 h and 48 h in 10 mg/L and 20 mg/L nitrite, respectively. In addition, CAT and SOD activity showed changes in response to nitrite stress that mirrored the induced expression of MjCAT and MjMnSOD, and prolonged nitrite exposure reduced the activity of CAT. This study provided basic data for further elucidating the responses of shrimp to nitrite stress at the molecular level. Copyright © 2016. Published by Elsevier Ltd.

Potential Role of Nitrite for Abiotic Fe(II) Oxidation and Cell Encrustation during Nitrate Reduction by Denitrifying Bacteria

PubMed Central

Klueglein, Nicole; Zeitvogel, Fabian; Stierhof, York-Dieter; Floetenmeyer, Matthias; Konhauser, Kurt O.; Obst, Martin

2014-01-01

Microorganisms have been observed to oxidize Fe(II) at neutral pH under anoxic and microoxic conditions. While most of the mixotrophic nitrate-reducing Fe(II)-oxidizing bacteria become encrusted with Fe(III)-rich minerals, photoautotrophic and microaerophilic Fe(II) oxidizers avoid cell encrustation. The Fe(II) oxidation mechanisms and the reasons for encrustation remain largely unresolved. Here we used cultivation-based methods and electron microscopy to compare two previously described nitrate-reducing Fe(II) oxidizers ( Acidovorax sp. strain BoFeN1 and Pseudogulbenkiania sp. strain 2002) and two heterotrophic nitrate reducers (Paracoccus denitrificans ATCC 19367 and P. denitrificans Pd 1222). All four strains oxidized ∼8 mM Fe(II) within 5 days in the presence of 5 mM acetate and accumulated nitrite (maximum concentrations of 0.8 to 1.0 mM) in the culture media. Iron(III) minerals, mainly goethite, formed and precipitated extracellularly in close proximity to the cell surface. Interestingly, mineral formation was also observed within the periplasm and cytoplasm; intracellular mineralization is expected to be physiologically disadvantageous, yet acetate consumption continued to be observed even at an advanced stage of Fe(II) oxidation. Extracellular polymeric substances (EPS) were detected by lectin staining with fluorescence microscopy, particularly in the presence of Fe(II), suggesting that EPS production is a response to Fe(II) toxicity or a strategy to decrease encrustation. Based on the data presented here, we propose a nitrite-driven, indirect mechanism of cell encrustation whereby nitrite forms during heterotrophic denitrification and abiotically oxidizes Fe(II). This work adds to the known assemblage of Fe(II)-oxidizing bacteria in nature and complicates our ability to delineate microbial Fe(II) oxidation in ancient microbes preserved as fossils in the geological record. PMID:24271182

Nitrates, Nitrites, and Health. Bulletin 750.

ERIC Educational Resources Information Center

Deeb, Barbara S.; Sloan, Kenneth W.

This review is intended to assess available literature in order to define the range of nitrate/nitrite effects on animals. Though the literature deals primarily with livestock and experimental animals, much of the contemporary research is concerned with human nitrite intoxication. Thus, the effects on man are discussed where appropriate. Some of…

REDUCTION OF NITRATE THROUGH THE USE OF NITRATE REDUCTASE FOR THE SMARTCHEM AUTOANALYZER

EPA Science Inventory

The standard method for the determination of nitrate in drinking water, USEPA Method 353.2 “Determination of Nitrate-Nitrite by Automated Colorimetry,” employs cadmium as the reductant for the conversion of nitrate to nitrite. The nitrite is then analyzed colorimetrically by way ...

Carcinogenic N-nitro-dimethylamine from the reaction of the analgesic amidopyrine and nitrite extracted from foodstuffs.

PubMed

LaBar, J; Sander, J

1975-11-25

The reaction of the analgesic amidopyrine (100 mg) with nitrite extracted from cured meats and from spinach in varying degrees of spoilage was studied. Unde physiological conditions the carcinogenic dimethylnitrosamine was formed at milligram levels at nitrite concentrations as low as 4 mg (in 175 ml extracted from 100 g boiled ham). The rate of decrease in concentration in the human stomach after ingestion of amidopyrine and of nitrite contained in boiled ham or in a broth from boiled ham was also measured.

The kinetics for ammonium and nitrite oxidation under the effect of hydroxylamine.

PubMed

Wan, Xinyu; Xiao, Pengying; Zhang, Daijun; Lu, Peili; Yao, Zongbao; He, Qiang

2016-01-01

The kinetics for ammonium (NH4(+)) oxidation and nitrite (NO2(-)) oxidation under the effect of hydroxylamine (NH2OH) were studied by respirometry using the nitrifying sludge from a laboratory-scale sequencing batch reactor. Modified models were used to estimate kinetics parameters of ammonia and nitrite oxidation under the effect of hydroxylamine. An inhibition effect of hydroxylamine on the ammonia oxidation was observed under different hydroxylamine concentration levels. The self-inhibition coefficient of hydroxylamine oxidation and noncompetitive inhibition coefficient of hydroxylamine for nitrite oxidation was estimated by simulating exogenous oxygen-uptake rate profiles, respectively. The inhibitive effect of NH2OH on nitrite-oxidizing bacteria was stronger than on ammonia-oxidizing bacteria. This work could provide fundamental data for the kinetic investigation of the nitrification process.

Nitrite Formation from Hydroxylamine and Oximes by Pseudomonas aeruginosa

PubMed Central

Amarger, Noelle; Alexander, M.

1968-01-01

Nitrite was formed from hydroxylamine and several oximes by intact cells and extracts of Pseudomonas aeruginosa. The activity was induced by the presence of oximes in the culture medium. Nitroalkanes were not intermediates in the conversion of acetaldoxime, acetone oxime, or butanone oxime to nitrite, since nitromethane inhibited the formation of nitrite from the nitro compounds but not from the corresponding oximes. The oxime apparently functions as a constant source of hydroxylamine during growth of the bacterium. Hydroxylamine at low concentration was converted stoichiometrically to nitrite by extracts of the bacterium; high concentrations were inhibitory. Nicotinamide adenine dinucleotide phosphate, oxygen, and other unidentified cofactors were necessary for the reaction. Actively nitrifying extracts possessed no hydroxylamine-cytochrome c reductase activity. Hyponitrite, nitrous oxide, and nitric oxide were not metabolized. PMID:4384968

Major role of nitrite-oxidizing bacteria in dark ocean carbon fixation

NASA Astrophysics Data System (ADS)

Pachiadaki, Maria G.; Sintes, Eva; Bergauer, Kristin; Brown, Julia M.; Record, Nicholas R.; Swan, Brandon K.; Mathyer, Mary Elizabeth; Hallam, Steven J.; Lopez-Garcia, Purificacion; Takaki, Yoshihiro; Nunoura, Takuro; Woyke, Tanja; Herndl, Gerhard J.; Stepanauskas, Ramunas

2017-11-01

Carbon fixation by chemoautotrophic microorganisms in the dark ocean has a major impact on global carbon cycling and ecological relationships in the ocean’s interior, but the relevant taxa and energy sources remain enigmatic. We show evidence that nitrite-oxidizing bacteria affiliated with the Nitrospinae phylum are important in dark ocean chemoautotrophy. Single-cell genomics and community metagenomics revealed that Nitrospinae are the most abundant and globally distributed nitrite-oxidizing bacteria in the ocean. Metaproteomics and metatranscriptomics analyses suggest that nitrite oxidation is the main pathway of energy production in Nitrospinae. Microautoradiography, linked with catalyzed reporter deposition fluorescence in situ hybridization, indicated that Nitrospinae fix 15 to 45% of inorganic carbon in the mesopelagic western North Atlantic. Nitrite oxidation may have a greater impact on the carbon cycle than previously assumed.

[Electrical activity and circulatory effects of nitrite in the rat cerebrum].

PubMed

Shumilova, T E; Smirnov, A G; Shereshkov, V I; Fedorova, M A; Nozdrachev, A D

2015-01-01

An association between the cerebrum electrical activity (CEA) in rats, blood supply of its cortex microregions (linear blood flow), and general cerebrum blood flow under acute nitrite hypoxia was studied. The phase character of the change in hemodynamic indices and the total capacity of electroencephalography (EEG) spectrum for 75 min after sodium nitrite introduction (30 mg/kg of body weight) was detected. The first phase (30 min) was associated with cerebrum adaptation to hypotension caused by nitrite and was completed by EEG normalization. The second phase was characterized by pathological EEG changes (in spite of restoration of hemodynamics in the cerebrum) caused by the growth of oxygen debt in the nervous tissue as a result of a decrease in the blood oxygen capacity by 60-75 min of the effect of nitrite.

The Nitrite-Scavenging Properties of Catechol, Resorcinol, and Hydroquinone: A Comparative Study on Their Nitration and Nitrosation Reactions.

PubMed

Lu, Yunhao; Dong, Yanzuo; Li, Xueli; He, Qiang

2016-10-14

The nitration and nitrosation reactions of catechol, resorcinol, and hydroquinone (0.05 mmol/L) with sodium nitrite (0.05 mmol/L) at pH 3 and 37 °C were studied by using liquid chromatography and mass spectrometry (LC-MS) and atom charge analysis, which was aimed to provide chemical insight into the nitrite-scavenging behavior of polyphenols. The 3 benzenediols showed different mechanisms to scavenge nitrite due to their differences in hydroxyl position. Catechol was nitrated with 1 NO 2 group at the hydroxyl oxygen, and resorcinol was nitrosated with 2 NO groups at the C 2 and C 4 (or C 6 ) positions of the benzene ring. Hydroquinone could scavenge nitrite through both nitration and nitrosation mechanisms. The nitrated hydroquinone had 1 NO 2 group at the hydroxyl oxygen in the molecule, while the nitrosated 1 containing 2 NO groups at the benzene ring might have 3 structure probabilities. The results may provide a structure-activity understanding on the nitrite-scavenging property of polyphenols, so as to promote their application in the food industry for the removal of possibly toxic nitrites found in many vegetables and often in processed meat products. © 2016 Institute of Food Technologists®.

Sensitivity to nitrate and nitrite in pond-breeding amphibians from the Pacific Northwest, USA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marco, A.; Quilchano, C.; Blaustein, A.R.

1999-12-01

In static experiments, the authors studied the effects of nitrate and nitrate solutions on newly hatched larvae of five species of amphibians, namely Rana pretiosa, Rana aurora, Bufo boreas, Hyla regilla, and Ambystoma gracile. When nitrate or nitrite ions were added to the water, some larvae of some species reduced feeding activity, swam less vigorously, showed disequilibrium and paralysis, suffered abnormalities and edemas, and eventually died. The observed effects increased with both concentration and time, and there were significant differences in sensitivity among species. Ambrystoma gracile displayed the highest acute effect in water with nitrate and nitrite. The three ranidmore » species had acute effects in water with nitrite. In chronic exposures, R. pretiosa was the most sensitive species to nitrates and nitrites. All species showed 15-d LC50s lower than 2 mg N-NO{sub 2{sup {minus}}}/L. For both N ions, B. boreas was the least sensitive amphibian. All species showed a high morality at the US Environmental Protection Agency-recommended limits of nitrite for warm-water fishes and a significant larval mortality at the recommended limits of nitrite concentration for drinking water. The recommended levels of nitrate for warm-water fishes were highly toxic for R. pretiosa and A. gracile larvae.« less

Inhibition Of Washed Sludge With Sodium Nitrite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Congdon, J. W.; Lozier, J. S.

2012-09-25

This report describes the results of electrochemical tests used to determine the relationship between the concentration of the aggressive anions in washed sludge and the minimum effective inhibitor concentration. Sodium nitrate was added as the inhibitor because of its compatibility with the DWPF process. A minimum of 0.05M nitrite is required to inhibit the washed sludge simulant solution used in this study. When the worst case compositions and safety margins are considered, it is expected that a minimum operating limit of nearly 0.1M nitrite will be specified. The validity of this limit is dependent on the accuracy of the concentrationsmore » and solubility splits previously reported. Sodium nitrite additions to obtain 0.1M nitrite concentrations in washed sludge will necessitate the additional washing of washed precipitate in order to decrease its sodium nitrite inhibitor requirements sufficiently to remain below the sodium limits in the feed to the DWPF. Nitrite will be the controlling anion in "fresh" washed sludge unless the soluble chloride concentration is about ten times higher than predicted by the solubility splits. Inhibition of "aged" washed sludge will not be a problem unless significant chloride dissolution occurs during storage. It will be very important tomonitor the composition of washed sludge during processing and storage.« less

Acute, Sub-lethal Cyanide Poisoning in Mice is Ameliorated by Nitrite Alone: Complications Arising from Concomitant Administration of Nitrite and Thiosulfate as an Antidotal Combination

PubMed Central

Cambal, Leah K.; Swanson, Megan R.; Yuan, Quan; Weitz, Andrew C.; Li, Hui-Hua; Pitt, Bruce R.; Pearce, Linda L.; Peterson, Jim

2011-01-01

Sodium nitrite alone is shown to ameliorate sub-lethal cyanide toxicity in mice when given from ~1 hour before until 20 minutes after the toxic dose as demonstrated by the recovery of righting ability. An optimum dose (12 mg/kg) was determined to significantly relieve cyanide toxicity (5.0 mg/kg) when administered to mice intraperitoneally. Nitrite so administered was shown to rapidly produce NO in the bloodsteam as judged by the dose dependent appearance of EPR signals attributable to nitrosylhemoglobin and methemoglobin. It is argued that antagonism of cyanide inhibition of cytochrome c oxidase by NO is the crucial antidotal activity rather than the methemoglobin-forming action of nitrite. Concomitant addition of sodium thiosulfate to nitrite-treated blood resulted in the detection of sulfidomethemoblobin by EPR spectroscopy. Sulfide is a product of thiosulfate hydrolysis and, like cyanide, is known to be a potent inhibitor of cytochrome c oxidase; the effects of the two inhibitors being essentially additive under standard assay conditions, rather than dominated by either one. The findings afford a plausible explanation for an observed detrimental effect in mice associated with the use of the standard nitrite-thiosulfate combination therapy at sub-lethal levels of cyanide intoxication. PMID:21534623

Effect of nitrite on the formation of halonitromethanes during chlorination of organic matter from different origin

NASA Astrophysics Data System (ADS)

Hong, Huachang; Qian, Lingya; Xiao, Zhuoqun; Zhang, Jianqing; Chen, Jianrong; Lin, Hongjun; Yu, Haiying; Shen, Liguo; Liang, Yan

2015-12-01

Occurrence of halonitromethanes (HNMs) in drinking water has been a public concern due to the potential risks to human health. Though quite a lot of work has been carried out to understand the formation of HNMs, the relationship between HNMs formation and the nitrite remains unclear. In this study, the effects of nitrite on the formation of HNMs during chlorination of organic matter from different origin were assessed. Organic matter (OM) derived from phoenix tree (fallen leaves: FLOM; green leaves: GLOM) and Microcystis aeruginosa (intracellular organic matter: IOM) were used to mimic the allochthonous and autochthonous organic matter in surface water, respectively. Results showed that HNMs yields were significantly enhanced with the addition of nitrite, and the highest enhancement was observed for FLOM, successively followed by GLOM and IOM, suggesting that the contribution of nitrite to HNMs formation was positively related with SUVA (an indicator for aromaticity) of OM. Therefore, the nitrite contamination should be strictly controlled for the source water dominated by allochthonous OM, which may significantly reduce the formation of HNMs during chlorination. Moreover, given a certain nitrite level, the higher pH resulted in higher stimulation of HNM formation, yet the chlorine dose (always added in excess resulting in residual reactive chlorine), reaction time and temperature did not show obvious influence.

Post-anoxic denitrification via nitrite driven by PHB in feast-famine sequencing batch reactor.

PubMed

Chen, Hong-Bo; Yang, Qi; Li, Xiao-Ming; Wang, Yan; Luo, Kun; Zeng, Guang-Ming

2013-08-01

Recently, it was found that excess phosphorus removal could be induced by aerobic/extended-idle regime. In this study, an anoxic period was introduced after the aeration to realize simultaneous nitrogen and phosphorus removal. The results demonstrated that stable partial nitrification could be achieved by controlling the aeration duration at 2.5h because it could not only obtain a desirable ammonia oxidation to nitrite but also avoid the extensive aeration converting nitrite to nitrate, and moreover, the accumulated poly-3-hydroxybutyrate still remain in a relative sufficient concentration (1.5mmolCg(-1) VSS), which could subsequently served as internal carbon source for post-anoxic denitrification. The nitrite accumulation ratio was observed to have relatively high correlation with biological nutrient removal. Over stages with stable high-level nitrite accumulation, the process achieved desirable and stable nitrogen and phosphorus removal efficiencies averaging 95% and 99% respectively. Fluorescence in situ hybridization analysis showed that the faster growth rate of the ammonia oxidizing bacteria than the nitrite oxidizing bacteria was the main reason for achieving nitrite accumulation. In addition, the secondary phosphorus release was negligible and the process maintained excellent nutrient removal under low influent ammonia nitrogen. Copyright © 2013 Elsevier Ltd. All rights reserved.

Low nitrous oxide production through nitrifier-denitrification in intermittent-feed high-rate nitritation reactors.

PubMed

Su, Qingxian; Ma, Chun; Domingo-Félez, Carlos; Kiil, Anne Sofie; Thamdrup, Bo; Jensen, Marlene Mark; Smets, Barth F

2017-10-15

Nitrous oxide (N 2 O) production from autotrophic nitrogen conversion processes, especially nitritation systems, can be significant, requires understanding and calls for mitigation. In this study, the rates and pathways of N 2 O production were quantified in two lab-scale sequencing batch reactors operated with intermittent feeding and demonstrating long-term and high-rate nitritation. The resulting reactor biomass was highly enriched in ammonia-oxidizing bacteria, and converted ∼93 ± 14% of the oxidized ammonium to nitrite. The low DO set-point combined with intermittent feeding was sufficient to maintain high nitritation efficiency and high nitritation rates at 20-26 °C over a period of ∼300 days. Even at the high nitritation efficiencies, net N 2 O production was low (∼2% of the oxidized ammonium). Net N 2 O production rates transiently increased with a rise in pH after each feeding, suggesting a potential effect of pH on N 2 O production. In situ application of 15 N labeled substrates revealed nitrifier denitrification as the dominant pathway of N 2 O production. Our study highlights operational conditions that minimize N 2 O emission from two-stage autotrophic nitrogen removal systems. Copyright © 2017 Elsevier Ltd. All rights reserved.

A comparative study of nitrite reduction by synthetic and biogenic Fe(II-III) hydroxysalts green rusts: Evidence for hydroxyl-nitrite green rust formation as an intermediate reaction product.

NASA Astrophysics Data System (ADS)

Ona-Nguema, G.; Guerbois, D.; Morin, G.; Zhang, Y.; Noel, V.; Brest, J.

2013-12-01

The occurrence of high nitrite concentrations as a result of anthropogenic activities is an important water quality concern as it is highly toxic to human and fauna, and it is used as a nitrogen source for the assimilation process. The toxicity of nitrite is related to its transformation into carcinogenic N-nitroso compounds, which are suspected to be responsible for some gastric cancers, and to its ability to convert the hemoglobin to methaemoglobin what is then unable to fix oxygen and to transport it to the tissues, involving hypoxia and the blue-baby syndrome [1]. To reduce the adverse effect of nitrite on human health and on macroalgal blooms, any process enhancing the transformation of nitrite ions to nitrogen gas is of interest for the remediation of natural environments. To achieve this purpose the use of processes involving Fe(II)-containing minerals could be considered as one of the best options. Green-rusts are mixed Fe(II-III) layered double hydroxides commonly found in anoxic zones of natural environments such as sediments and hydromorphic soils. In such anoxic environments, green rust minerals play an important role in the biogeochemical redox cycling of iron and nitrogen, and can affect the speciation and mobility of many organic and inorganic contaminants. The present study investigates the reduction of nitrite by two synthetic and two biogenic green rusts. On the one hand, Fe(II-III) hydroxychloride and Fe(II-III) hydroxycarbonate green rusts were used as synthetic interlayer forms of GR, which are referred to as ';syn-GR(CO3)' and ';syn-GR(Cl)', respectively. On the other hand, the study was performed with biogenic Fe(II-III) hydroxycarbonate green rusts obtained from the bioreduction of two ferric precursors, either Fe(III)-oxyhydroxycarbonate or lepidocrocite; these biogenic green rusts are referred to as ';bio-GR(CO3)F' and ';bio-GR(CO3)L', respectively. For synthetic green rusts, results showed that the oxidation of both syn-GR(CO3) and syn-GR(Cl) led to the reduction of nitrite ions to ammonium, and that the production of ammonium depended on their Fe(II) content. XRD patterns indicated that both synthetic green rusts were fully oxidized into magnetite during the reaction with nitrite. For biogenic green rusts, the study revealed that both bio-GR(CO3)F and bio-GR(CO3)L were capable of reducing nitrite ions without ammonium production, suggesting the conversion of nitrite ions to nitrogen gas. Moreover, we provided evidence for the first time that the interactions of bio-GR(CO3)F with nitrite led to the formation of an hydroxy-nitrite green rust as a result of the incorporation of nitrite in the interlayer region of bio-GR(CO3)F; such an intercalation of nitrite ions was not observed in experiments with bio-GR(CO3)L. XRD analysis indicated that GR(NO2) was formed as an intermediate reaction product prior to the fully oxidation of GR to ferric oxyhydroxides. [1] Philips S., Laanbroek H. J. and Verstraete W. (2002). Rev. Environ. Sci. Biotechnol. 1, 115-141.

Tidal variability of nutrients in a coastal coral reef system influenced by groundwater

NASA Astrophysics Data System (ADS)

Wang, Guizhi; Wang, Shuling; Wang, Zhangyong; Jing, Wenping; Xu, Yi; Zhang, Zhouling; Tan, Ehui; Dai, Minhan

2018-02-01

To investigate variation in nitrite, nitrate, phosphate, and silicate in a spring-neap tide in a coral reef system influenced by groundwater discharge, we carried out a time-series observation of these nutrients and 228Ra, a tracer of groundwater discharge, in the Luhuitou fringing reef at Sanya Bay in the South China Sea. The maximum 228Ra, 45.3 dpm 100 L-1, appeared at low tide and the minimum, 14.0 dpm 100 L-1, appeared during a flood tide in the spring tide. The activity of 228Ra was significantly correlated with water depth and salinity in the spring-neap tide, reflecting the tidal-pumping feature of groundwater discharge. Concentrations of all nutrients exhibited strong diurnal variation, with a maximum in the amplitude of the diel change for nitrite, nitrate, phosphate, and silicate in the spring tide of 0.46, 1.54, 0.12, and 2.68 µM, respectively. Nitrate and phosphate were negatively correlated with water depth during the spring tide but showed no correlation during the neap tide. Nitrite was positively correlated with water depth in the spring and neap tide due to mixing of nitrite-depleted groundwater and nitrite-rich offshore seawater. They were also significantly correlated with salinity (R2 ≥ 0.9 and P < 0.05) at the ebb flow of the spring tide, negative for nitrate and phosphate and positive for nitrite, indicating the mixing of nitrite-depleted, nitrate- and phosphate-rich less saline groundwater and nitrite-rich, nitrate- and phosphate-depleted saline offshore seawater. We quantified variation in oxidized nitrogen (NOx) and phosphate contributed by biological processes based on deviations from mixing lines of these nutrients. During both the spring and neap tide biologically contributed NOx and phosphate were significantly correlated with regression slopes of 4.60 (R2 = 0.16) in the spring tide and 13.4 (R2 = 0.75) in the neap tide, similar to the composition of these nutrients in the water column, 5.43 (R2 = 0.27) and 14.2 (R2 = 0.76), respectively. This similarity indicates that the composition of nutrients in the water column of the reef system was closely related with biological processes during both tidal periods, but the biological influence appeared to be less dominant, as inferred from the less significant correlations (R2 = 0.16) during the spring tide when groundwater discharge was more prominent. Thus, the variability of nutrients in the coral reef system was regulated mainly by biological uptake and release in a spring-neap tide and impacted by mixing of tidally driven groundwater and offshore seawater during spring tide.

Maternal characteristics associated with the dietary intake of nitrates, nitrites, and nitrosamines in women of child-bearing age: a cross-sectional study

PubMed Central

2010-01-01

Background Multiple N-nitroso compounds have been observed in animal studies to be both mutagenic and teratogenic. Human exposure to N-nitroso compounds and their precursors, nitrates and nitrites, can occur through exogenous sources, such as diet, drinking water, occupation, or environmental exposures, and through endogenous exposures resulting from the formation of N-nitroso compounds in the body. Very little information is available on intake of nitrates, nitrites, and nitrosamines and factors related to increased consumption of these compounds. Methods Using survey and dietary intake information from control women (with deliveries of live births without major congenital malformations during 1997-2004) who participated in the National Birth Defects Prevention Study (NBDPS), we examined the relation between various maternal characteristics and intake of nitrates, nitrites, and nitrosamines from dietary sources. Estimated intake of these compounds was obtained from the Willet Food Frequency Questionnaire as adapted for the NBDPS. Multinomial logistic regression models were used to estimate odds ratios and 95% confidence intervals for the consumption of these compounds by self-reported race/ethnicity and other maternal characteristics. Results Median intake per day for nitrates, nitrites, total nitrites (nitrites + 5% nitrates), and nitrosamines was estimated at 40.48 mg, 1.53 mg, 3.69 mg, and 0.472 μg respectively. With the lowest quartile of intake as the referent category and controlling for daily caloric intake, factors predicting intake of these compounds included maternal race/ethnicity, education, body mass index, household income, area of residence, folate intake, and percent of daily calories from dietary fat. Non-Hispanic White participants were less likely to consume nitrates, nitrites, and total nitrites per day, but more likely to consume dietary nitrosamines than other participants that participated in the NBDPS. Primary food sources of these compounds also varied by maternal race/ethnicity. Conclusions Results of this study indicate that intake of nitrates, nitrites, and nitrosamines vary considerably by race/ethnicity, education, body mass index, and other characteristics. Further research is needed regarding how consumption of foods high in nitrosamines and N-nitroso precursors might relate to risk of adverse pregnancy outcomes and chronic diseases. PMID:20170520

Isolated and combined exposure to ammonia and nitrite in giant freshwater pawn (Macrobrachium rosenbergii): effects on the oxidative stress, antioxidant enzymatic activities and apoptosis in haemocytes.

PubMed

Zhang, Yufan; Ye, Chaoxia; Wang, Anli; Zhu, Xuan; Chen, Changhong; Xian, Jianan; Sun, Zhenzhu

2015-10-01

The residual contaminators such as ammonia and nitrite are widely considered as relevant sources of aquatic environmental pollutants, posing a great threat to shrimp survival. To study the toxicological effects of ammonia and nitrite exposure on the innate immune response in invertebrates, we investigated the oxidative stress and apoptosis in haemocytes of freshwater prawn (Macrobrachium rosenbergii) under isolated and combined exposure to ammonia and nitrite in order to provide useful information about adult prawn immune responses. M. rosenbergii (13.44 ± 2.75 g) were exposed to 0, 5, and 25 mg/L total ammonia-N (TAN) and 0, 5, and 20 mg/L nitrite-N for 24 h. All ammonia concentrations were combined with all nitrite concentrations, making a total of nine treatments studied. Following the exposure treatment, antioxidant enzyme activity, reactive oxygen species (ROS) generation, nitric oxide (NO) generation, and apoptotic cell ratio of haemocytes were measured using flow cytometry. Results indicated that ROS generation was sensitive to the combined effect of ammonia and nitrite, which subsequently affected the Cu-Zn SOD activity. In addition, CAT showed the highest activity at 5 mg/L TAN while GPx decreased at 5 mg/L TAN and returned towards baseline at 25 mg/L. NO generation synchronized with the apoptotic cell ratio in haemocytes, indicating that NO production was closely associated with programmed cell death. Both NO production and apoptotic ratios significantly decreased following 25 mg/L TAN, which may be due to the antagonistic regulation of NO and GPx. We hypothesized that the toxicological effect of nitrite exhibited less change in physiological changes compared to that of ammonia, because of the high tolerance to nitrite exposure in mature M. rosenbergii and/or the competitive effects of chloride ions. Taken together, these results showed that ammonia and nitrite caused a series of combined oxidative stress and apoptosis in M. rosenbergi, but further studies are of great need to explain the mechanisms.

Maternal characteristics associated with the dietary intake of nitrates, nitrites, and nitrosamines in women of child-bearing age: a cross-sectional study.

PubMed

Griesenbeck, John S; Brender, Jean D; Sharkey, Joseph R; Steck, Michelle D; Huber, John C; Rene, Antonio A; McDonald, Thomas J; Romitti, Paul A; Canfield, Mark A; Langlois, Peter H; Suarez, Lucina

2010-02-19

Multiple N-nitroso compounds have been observed in animal studies to be both mutagenic and teratogenic. Human exposure to N-nitroso compounds and their precursors, nitrates and nitrites, can occur through exogenous sources, such as diet, drinking water, occupation, or environmental exposures, and through endogenous exposures resulting from the formation of N-nitroso compounds in the body. Very little information is available on intake of nitrates, nitrites, and nitrosamines and factors related to increased consumption of these compounds. Using survey and dietary intake information from control women (with deliveries of live births without major congenital malformations during 1997-2004) who participated in the National Birth Defects Prevention Study (NBDPS), we examined the relation between various maternal characteristics and intake of nitrates, nitrites, and nitrosamines from dietary sources. Estimated intake of these compounds was obtained from the Willet Food Frequency Questionnaire as adapted for the NBDPS. Multinomial logistic regression models were used to estimate odds ratios and 95% confidence intervals for the consumption of these compounds by self-reported race/ethnicity and other maternal characteristics. Median intake per day for nitrates, nitrites, total nitrites (nitrites + 5% nitrates), and nitrosamines was estimated at 40.48 mg, 1.53 mg, 3.69 mg, and 0.472 microg respectively. With the lowest quartile of intake as the referent category and controlling for daily caloric intake, factors predicting intake of these compounds included maternal race/ethnicity, education, body mass index, household income, area of residence, folate intake, and percent of daily calories from dietary fat. Non-Hispanic White participants were less likely to consume nitrates, nitrites, and total nitrites per day, but more likely to consume dietary nitrosamines than other participants that participated in the NBDPS. Primary food sources of these compounds also varied by maternal race/ethnicity. Results of this study indicate that intake of nitrates, nitrites, and nitrosamines vary considerably by race/ethnicity, education, body mass index, and other characteristics. Further research is needed regarding how consumption of foods high in nitrosamines and N-nitroso precursors might relate to risk of adverse pregnancy outcomes and chronic diseases.

Proton-coupled electron transfer in the catalytic cycle of Alcaligenes xylosoxidans copper-dependent nitrite reductase.

PubMed

Leferink, Nicole G H; Han, Cong; Antonyuk, Svetlana V; Heyes, Derren J; Rigby, Stephen E J; Hough, Michael A; Eady, Robert R; Scrutton, Nigel S; Hasnain, S Samar

2011-05-17

We demonstrated recently that two protons are involved in reduction of nitrite to nitric oxide through a proton-coupled electron transfer (ET) reaction catalyzed by the blue Cu-dependent nitrite reductase (Cu NiR) of Alcaligenes xylosoxidans (AxNiR). Here, the functionality of two putative proton channels, one involving Asn90 and the other His254, is studied using single (N90S, H254F) and double (N90S--H254F) mutants. All mutants studied are active, indicating that protons are still able to reach the active site. The H254F mutation has no effect on the catalytic activity, while the N90S mutation results in ~70% decrease in activity. Laser flash-photolysis experiments show that in H254F and wild-type enzyme electrons enter at the level of the T1Cu and then redistribute between the two Cu sites. Complete ET from T1Cu to T2Cu occurs only when nitrite binds at the T2Cu site. This indicates that substrate binding to T2Cu promotes ET from T1Cu, suggesting that the enzyme operates an ordered mechanism. In fact, in the N90S and N90S--H254F variants, where the T1Cu site redox potential is elevated by ∼60 mV, inter-Cu ET is only observed in the presence of nitrite. From these results it is evident that the Asn90 channel is the main proton channel in AxNiR, though protons can still reach the active site if this channel is disrupted. Crystallographic structures provide a clear structural rationale for these observations, including restoration of the proton delivery via a significant movement of the loop connecting the T1Cu ligands Cys130 and His139 that occurs on binding of nitrite. Notably, a role for this loop in facilitating interaction of cytochrome c(551) with Cu NiR has been suggested previously based on a crystal structure of the binary complex.

21 CFR 172.177 - Sodium nitrite used in processing smoked chub.

Code of Federal Regulations, 2010 CFR

2010-04-01

... SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO.... The food additive sodium nitrite may be safely used in combination with salt (NaCl) to aid in... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Sodium nitrite used in processing smoked chub. 172...

78 FR 69646 - Sodium Nitrite From the People's Republic of China: Final Results of the Expedited First Sunset...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-11-20

... DEPARTMENT OF COMMERCE International Trade Administration [C-570-926] Sodium Nitrite From the... Commerce (``the Department'') finds that revocation of the countervailing duty (``CVD'') order on sodium..., the Department initiated the first sunset review of the CVD order on sodium nitrite from the PRC...

9 CFR 319.2 - Products and nitrates and nitrites.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 9 Animals and Animal Products 2 2010-01-01 2010-01-01 false Products and nitrates and nitrites. 319.2 Section 319.2 Animals and Animal Products FOOD SAFETY AND INSPECTION SERVICE, DEPARTMENT OF... and nitrates and nitrites. Any product, such as frankfurters and corned beef, for which there is a...

9 CFR 319.2 - Products and nitrates and nitrites.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 9 Animals and Animal Products 2 2013-01-01 2013-01-01 false Products and nitrates and nitrites. 319.2 Section 319.2 Animals and Animal Products FOOD SAFETY AND INSPECTION SERVICE, DEPARTMENT OF... and nitrates and nitrites. Any product, such as frankfurters and corned beef, for which there is a...

9 CFR 319.2 - Products and nitrates and nitrites.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 9 Animals and Animal Products 2 2012-01-01 2012-01-01 false Products and nitrates and nitrites. 319.2 Section 319.2 Animals and Animal Products FOOD SAFETY AND INSPECTION SERVICE, DEPARTMENT OF... and nitrates and nitrites. Any product, such as frankfurters and corned beef, for which there is a...

9 CFR 319.2 - Products and nitrates and nitrites.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 9 Animals and Animal Products 2 2011-01-01 2011-01-01 false Products and nitrates and nitrites. 319.2 Section 319.2 Animals and Animal Products FOOD SAFETY AND INSPECTION SERVICE, DEPARTMENT OF... and nitrates and nitrites. Any product, such as frankfurters and corned beef, for which there is a...

9 CFR 319.2 - Products and nitrates and nitrites.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 9 Animals and Animal Products 2 2014-01-01 2014-01-01 false Products and nitrates and nitrites. 319.2 Section 319.2 Animals and Animal Products FOOD SAFETY AND INSPECTION SERVICE, DEPARTMENT OF... and nitrates and nitrites. Any product, such as frankfurters and corned beef, for which there is a...

Biogenic amine formation and nitrite reactions in meat batter as affected by high-pressure processing and chilled storage.

PubMed

Ruiz-Capillas, C; Aller-Guiote, P; Carballo, J; Colmenero, F Jiménez

2006-12-27

Changes in biogenic amine formation and nitrite depletion in meat batters as affected by pressure-temperature combinations (300 MPa/30 min/7, 20, and 40 degrees C), cooking process (70 degrees C/30 min), and storage (54 days/2 degrees C) were studied. Changes in residual nitrite concentration in raw meat batters were conditioned by the temperature and not by the pressure applied. Cooking process decreased (P < 0.05) the residual nitrite concentration in all samples. High-pressure processing and cooking treatment increased (P < 0.05) the nitrate content. Whereas protein-bound nitrite concentration decreased with pressure processing, no effect was observed with the heating process of meat batters. High-pressure processing conditions had no effect on the rate of residual nitrite loss throughout the storage. The application of high pressure decreased (P < 0.05) the concentration of some biogenic amines (tyramine, agmatine, and spermine). Irrespective of the high processing conditions, generally, throughout storage biogenic amine levels did not change or increased, although quantitatively this effect was not very important.

Experimental studies of methemoglobinemia due to percutaneous absorption of sodium nitrite.

PubMed

Saito, T; Takeichi, S; Nakajima, Y; Yukawa, N; Osawa, M

1997-01-01

Methemoglobin formation caused by a liniment solution containing sodium nitrite (30 g/L and 140 g/L) was studied in rats with normal or abraded skin, by measuring the methemoglobin concentration before and after application of liniment solutions with differing nitrite concentration. Each liniment solution (120 microL) was applied. Methemoglobin was measured for 180 minutes using a hemoximeter. Simultaneously, arterial blood pressure and cutaneous blood flow was measured by laser Doppler flowmetry and a pressure transducer. After the application of each liniment solution to normal skin, the methemoglobin concentration was not significantly modified depending on the time after application. Application of liniment solution to abraded skin (140 g/L) resulted in a marked increase in methemoglobin concentration. A remarkable decrease in arterial blood pressure and subcutaneous blood flow were observed after application of liniment solution to abraded skin (140 g/L). Each of these findings are characteristic of nitrite and they imply the percutaneous absorption of nitrite. Regardless of the nitrite concentration, the methemoglobin concentration was consistently higher in abraded skin than in normal skin.

Microbial mediated iron redox cycling in Fe (hydr)oxides for nitrite removal.

PubMed

Lu, Yongsheng; Xu, Lu; Shu, Weikang; Zhou, Jizhi; Chen, Xueping; Xu, Yunfeng; Qian, Guangren

2017-01-01

Nitrite, at an environmentally relevant concentration, was significantly reduced with iron (hydr)oxides mediated by Shewanella oneidensis MR-1. The average nitrite removal rates of 1.28±0.08 and 0.65±0.02(mgL -1 )h -1 were achieved with ferrihydrite and magnetite, respectively. The results showed that nitrite removal was able to undergo multiple redox cycles with iron (hydr)oxides mediated by Shewanella oneidensis MR-1. During the bioreduction of the following cycles, biogenic Fe(II) was subsequently chemically oxidized to Fe(III), which is associated with nitrite reduction. There was 11.18±1.26mgL -1 of NH 4 + -N generated in the process of redox cycling of ferrihydrite. Additionally, results obtained by using X-ray diffraction showed that ferrihydrite and magnetite remained mainly stable in the system. This study indicated that redox cycling of Fe in iron (hydr)oxides was a potential process associated with NO 2 - -N removal from solution, and reduced most nitrite abiotically to gaseous nitrogen species. Copyright © 2016 Elsevier Ltd. All rights reserved.

Sodium nitrite: the "cure" for nitric oxide insufficiency.

PubMed

Parthasarathy, Deepa K; Bryan, Nathan S

2012-11-01

This process of "curing" food is a long practice that dates back thousands of years long before refrigeration or food safety regulations. Today food safety and mass manufacturing are dependent upon safe and effective means to cure and preserve foods including meats. Nitrite remains the most effective curing agent to prevent food spoilage and bacterial contamination. Despite decades of rigorous research on its safety and efficacy as a curing agent, it is still regarded by many as a toxic undesirable food additive. However, research within the biomedical science community has revealed enormous therapeutic benefits of nitrite that is currently being developed as novel therapies for conditions associated with nitric oxide (NO) insufficiency. Much of the same biochemistry that has been understood for decades in the meat industry has been rediscovered in human physiology. This review will highlight the fundamental biochemistry of nitrite in human physiology and highlight the risk benefit evaluation surrounding nitrite in food and meat products. Foods or diets enriched with nitrite can have profound positive health benefits. Copyright © 2012 Elsevier Ltd. All rights reserved.

Biological nitrification/denitrification of high sodium nitrite (navy shipyard) wastewater.

PubMed

Kamath, S; Sabatini, D A; Canter, L W

1991-01-01

In the hydroblasting of ships' boiler tubes, a wastewater high in nitrite (as high as 1200 mg litre(-1)) is produced by the US Navy. This research has evaluated the use of a suspended-growth biological system to treat this wastewater by denitrification. Two biological treatment configurations were evaluated (direct denitrification versus nitrification/denitrification) with nitrification/denitrification producing better nitrite removal efficiencies (54 to 62% versus 40%, respectively). The introduction of metals (cadmium, chromium, lead, copper and iron) in concentrations typical for this wastewater did not inhibit the nitrite removal efficiencies. The influent metal concentrations ranged from 0.02 mg litre(-1) for cadmium to 22 mg litre(-1) for iron and the metal removal efficiencies ranged from 4.8% for cadmium to 50% for copper. Increasing sludge age resulted in improved nitrite removal efficiencies (52%, 57% and 74% for sludge ages of 4, 6 and 8 days, respectively). The resulting biokinetic constants were similar to those reported by others for lower influent concentrations of nitrite or nitrate (Ygs=0.02 mg/mg; Ygn=0.16 mg/mg; Yb=0.8 mg/mg; and b=0.006 h(-1)).

Increase in nitrite content and functionality of ethanolic extracts of Perilla frutescens following treatment with atmospheric pressure plasma.

PubMed

Jung, Samooel; Lee, Chul Woo; Lee, Juri; Yong, Hae In; Yum, Su Jin; Jeong, Hee Gon; Jo, Cheorun

2017-12-15

This study investigated the effect of atmospheric pressure plasma (APP) treatment on nitrite content and functionality of plant extracts. Ethanolic extracts of Perilla frutescens (EEP) were prepared and treated with APP for 60min. Nitrite content increased from 0 to 45.8mg/l in EEP after APP treatment for 60min. Antimicrobial activity of EEP against Clostridium perfringens and Salmonella Typhimurium was increased by APP with no influence on antioxidative activity (p<0.05). Lyophilized EEP (LEEP) treated with APP for 60min contained 3.74mg/g nitrite. The control (LEEP without APP) contained no nitrite. The minimum inhibitory concentration (MIC) of LEEP for C. perfringens was 200µg/ml. The control did not inhibit C. perfringens growth between 25 and 1000µg/ml. MICs of LEEP and the control against S. Typhimurium were 25 and 50µg/ml, respectively. New nitrite sources with increased antimicrobial activity can be produced from natural plants by APP treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

A genetic screen reveals a periplasmic copper chaperone required for nitrite reductase activity in pathogenic Neisseria.

PubMed

Jen, Freda E-C; Djoko, Karrera Y; Bent, Stephen J; Day, Christopher J; McEwan, Alastair G; Jennings, Michael P

2015-09-01

Under conditions of low oxygen availability, Neisseria meningitidis and Neisseria gonorrhoeae are able to respire via a partial denitrification pathway in which nitrite is converted to nitrous oxide. In this process, nitrite reductase (AniA), a copper (Cu)-containing protein converts nitrite to NO, and this product is converted to nitrous oxide by nitric oxide reductase (NorB). NorB also confers protection against toxic NO, and so we devised a conditional lethal screen, using a norB mutant, to identify mutants that were resistant to nitrite-dependent killing. After random-deletion mutagenesis of N. meningitidis, this genetic screen identified a gene encoding a Cu chaperone that is essential for AniA function, AccA. Purified AccA binds one Cu (I) ion and also possesses a second binding site for Cu (II). This novel periplasmic Cu chaperone (AccA) appears to be essential for provision of Cu ions to AniA of pathogenic Neisseria to generate an active nitrite reductase. Apart from the Neisseria genus, AccA is distributed across a wide range of environmental Proteobacteria species. © FASEB.

Short communication: Use of a mixture of sodium nitrite, sodium benzoate, and potassium sorbate in aerobically challenged silages.

PubMed

Knicky, Martin; Spörndly, Rolf

2015-08-01

Aerobic instability is still a common problem with many types of silages, particularly well-fermented silages. This study evaluated the effect of adding an additive mixture based on sodium nitrite, sodium benzoate, and potassium sorbate to a variety of crop materials on fermentation quality and aerobic stability of silages. Ensiling conditions were challenged by using a low packing density (104±4.3kg of dry matter/m(3)) of forage and allowing air ingression into silos (at 14 and 7 d before the end of the storage, for 8 h per event). Additive-treated silages were found to have significantly lower pH and reduced formation of ammonia-N, 2.3-butanediol, and ethanol compared with untreated control silages. Yeast growth was significantly reduced by additive treatment in comparison with untreated control silage. Consequently, additive-treated silages were considerably more aerobically stable (6.7 d) than untreated control silages (0.5 d). Overall, adding 5mL/kg of fresh crop of the additive based on sodium nitrite, sodium benzoate, and potassium sorbate reduced undesirable microorganisms in silages and thereby provided suitable ensiling conditions and prolonged aerobic stability, even under air-challenged laboratory ensiling conditions. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Development of a new fluorescent probe: 1,3,5,7-tetramethyl-8-(4'-aminophenyl)-4,4-difluoro-4-bora-3a,4a-diaza- s-indacence for the determination of trace nitrite

NASA Astrophysics Data System (ADS)

Li, Mengling; Wang, Hong; Zhang, Xian; Zhang, Hua-shan

2004-03-01

A new fluorescent probe, 1,3,5,7-tetramethyl-8-(4'-aminophenyl)-4,4-difluoro-4-bora-3a,4a-diaza- s-indacence (TMABODIPY) has been developed for the determination of trace nitrite in terms of the reaction of nitrite with TMABODIPY first in acidic solution and then in alkaline solution to form diazotate, a stable and highly fluorescent reagent. The method offered the advantage of specificity, sensitivity and simplicity. The linear calibration range for nitrite was 8-300 nmol l -1 s with a 3 σ detection limit of 0.65 nmol l -1. The proposed method has been applied to monitor the trace nitrite in drinking water and vegetable without extraction.

Ammonia from iron(II) reduction of nitrite and the Strecker synthesis: do iron(II) and cyanide interfere with each other?

NASA Technical Reports Server (NTRS)

Summers, D. P.; Lerner, N.

1998-01-01

The question of whether the production of ammonia, from the reduction of nitrite by iron(II), is compatible with its use in the Strecker synthesis of amino acids, or whether the iron and the cyanide needed for the Strecker synthesis interfere with each other, is addressed. Results show that the presence of iron(II) appears to have little, or no, effect on the Strecker synthesis. The presence of cyanide does interfere with reduction of nitrite, but the reduction proceeds at cyanide/iron ratios of less than 4:1. At ratios of about 2:1 and less there is only a small effect. The reduction of nitrite and the Strecker can be combined to proceed in each other's presence, to yield glycine from a mixture of nitrite, Fe+2, formaldehyde, and cyanide.

Growth from spores of Clostridium perfringens in the presence of sodium nitrite.

PubMed

Labbe, R G; Duncan, C L

1970-02-01

The method by which sodium nitrite may act to prevent germination or outgrowth, or both, of heat-injured spores in canned cured meats was investigated by using Clostridium perfringens spores. Four possible mechanisms were tested: (i) prevention of germination of the heat-injured spores, (ii) prior combination with a component in a complex medium to prevent germination of heat-injured spores, (iii) inhibition of outgrowth of heat-injured spores, and (iv) induction of germination (which would render the spore susceptible to thermal inactivation). Only the third mechanism was effective with the entire spore population when levels of sodium nitrite commercially acceptable in canned cured meats were used. Concentrations of 0.02 and 0.01% prevented outgrowth of heat-sensitive and heat-resistant spores, respectively. Nitrite-induced germination occurred with higher sodium nitrite concentrations.

Major role of nitrite-oxidizing bacteria in dark ocean carbon fixation.

PubMed

Pachiadaki, Maria G; Sintes, Eva; Bergauer, Kristin; Brown, Julia M; Record, Nicholas R; Swan, Brandon K; Mathyer, Mary Elizabeth; Hallam, Steven J; Lopez-Garcia, Purificacion; Takaki, Yoshihiro; Nunoura, Takuro; Woyke, Tanja; Herndl, Gerhard J; Stepanauskas, Ramunas

2017-11-24

Carbon fixation by chemoautotrophic microorganisms in the dark ocean has a major impact on global carbon cycling and ecological relationships in the ocean's interior, but the relevant taxa and energy sources remain enigmatic. We show evidence that nitrite-oxidizing bacteria affiliated with the Nitrospinae phylum are important in dark ocean chemoautotrophy. Single-cell genomics and community metagenomics revealed that Nitrospinae are the most abundant and globally distributed nitrite-oxidizing bacteria in the ocean. Metaproteomics and metatranscriptomics analyses suggest that nitrite oxidation is the main pathway of energy production in Nitrospinae. Microautoradiography, linked with catalyzed reporter deposition fluorescence in situ hybridization, indicated that Nitrospinae fix 15 to 45% of inorganic carbon in the mesopelagic western North Atlantic. Nitrite oxidation may have a greater impact on the carbon cycle than previously assumed. Copyright © 2017, American Association for the Advancement of Science.

Dietary Plant Sterols Supplementation Increases In Vivo Nitrite and Nitrate Production in Healthy Adults: A Randomized, Controlled Study.

PubMed

Ho, Xing Lin; Loke, Wai Mun

2017-07-01

A randomized, double-blinded, placebo-controlled and crossover study was conducted to simultaneously measure the effects, 3 h after consumption and after 4-wk daily exposure to plant sterols-enriched food product, on in vivo nitrite and nitrate production in healthy adults. Eighteen healthy participants (67% female, 35.3 [mean] ± 9.5 [SD] years, mean body mass index 22.8 kg/m 2 ) received 2 soy milk (20 g) treatments daily: placebo and one containing 2.0 g free plant sterols equivalent of their palmityl esters (β-sitosterol, 55%; campesterol, 29%; and stigmasterol, 23%). Nitrite and nitrate concentrations were measured in the blood plasma and urine, using stable isotope-labeled gas chromatography-mass spectrometry. L-arginine and asymmetric dimethylarginine concentrations in blood serum were measured using commercially available enzyme immunoassays. Nitrite and nitrate concentrations in blood plasma (nitrite 5.83 ± 0.50 vs. 4.52 ± 0.27; nitrate 15.78 ± 0.96 vs. 13.43 ± 0.81 μmol/L) and urine (nitrite 1.12 ± 0.22 vs. 0.92 ± 0.36, nitrate 12.23 ± 1.15 vs. 9.71 ± 2.04 μmol/L) were significantly elevated after 4-wk plant sterols supplementation Placebo and 3-h treatments did not affect the blood plasma and urinary concentrations of nitrite and nitrate. Circulating levels of L-arginine and asymmetric dimethylarginine were unchanged in the placebo and treatment arms. Total plant sterols, β-Sitosterol, campesterol, and stigmasterol concentrations were significantly elevated after 4-wk treatments compared to the placebo and 3-h treatments. Blood plasma nitrite and nitrate concentrations correlated significantly with the plasma total and specific plant sterol concentrations. Our results suggest that dietary plant sterols, in the combination used, can upregulate nitrite, and nitrate production in vivo. © 2017 Institute of Food Technologists®.

Nitrite oxidation kinetics of two Nitrospira strains: The quest for competition and ecological niche differentiation.

PubMed

Ushiki, Norisuke; Jinno, Masaru; Fujitani, Hirotsugu; Suenaga, Toshikazu; Terada, Akihiko; Tsuneda, Satoshi

2017-05-01

Nitrite oxidation is an aerobic process of the nitrogen cycle in natural ecosystems, and is performed by nitrite-oxidizing bacteria (NOB). Also, nitrite oxidation is a rate-limiting step of nitrogen removal in wastewater treatment plants (WWTPs). Although Nitrospira is known as dominant NOB in WWTPs, information on their physiological properties and kinetic parameters is limited. Here, we report the kinetic parameters and inhibition of nitrite oxidation by free ammonia in pure cultures of Nitrospira sp. strain ND1 and Nitrospira japonica strain NJ1, which were previously isolated from activated sludge in a WWTP. The maximum nitrite uptake rate ( [Formula: see text] ) and the half-saturation constant for nitrite uptake ( [Formula: see text] ) of strains ND1 and NJ1 were 45 ± 7 and 31 ± 5 (μmol NO 2 - /mg protein/h), and 6 ± 1 and 10 ± 2 (μM NO 2 - ), respectively. The [Formula: see text] and [Formula: see text] of two strains indicated that they adapt to low-nitrite-concentration environments like activated sludge. The half-saturation constants for oxygen uptake ( [Formula: see text] ) of the two strains were 4.0±2.5 and 2.6±1.1 (μM O 2 ), respectively. The [Formula: see text] values of the two strains were lower than those of other NOB, suggesting that Nitrospira in activated sludge could oxidize nitrite in the hypoxic environments often found in the interiors of biofilms and flocs. The inhibition thresholds of the two strains by free ammonia were 0.85 and 4.3 (mg-NH 3 l -1 ), respectively. Comparing the physiological properties of the two strains, we suggest that tolerance for free ammonia determines competition and partitioning into ecological niches among Nitrospira populations. Copyright © 2017 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Changes in nitrate and nitrite content of four vegetables during storage at refrigerated and ambient temperatures.

PubMed

Chung, J-C; Chou, S-S; Hwang, D-F

2004-04-01

The nitrate and nitrite contents of four kinds of vegetables (spinach, crown daisy, organic Chinese spinach and organic non-heading Chinese cabbage) in Taiwan were determined during storage at both refrigerated (5 +/- 1 degrees C) and ambient temperatures (22 +/- 1 degrees C) for 7 days. During storage at ambient temperature, nitrate levels in the vegetables dropped significantly from the third day while nitrite levels increased dramatically from the fourth day of storage. However, refrigerated storage did not lead to changes in nitrate and nitrite levels in the vegetables over 7 days.

Effects of waterborne nitrite on hematological parameters and stress indicators in olive flounders, Paralichthys olivaceus, raised in bio-floc and seawater.

PubMed

Kim, Jun-Hwan; Kim, Jin-Young; Lim, Lok-Ji; Kim, Su Kyoung; Choi, Hye Sung; Hur, Young Baek

2018-06-11

Juvenile olive flounders, Paralichthys olivaceus (mean weight 2.69 ± 0.31 g), were raised in bio-floc and seawater for six months, these P. olivaceus (mean weight 280.1 ± 10.5 g, mean length 28.37 ± 2.3 cm) were exposed to different concentrations of waterborne nitrite (0, 25, 50, 100, and 200 mg NO 2 - /L) for 7 days. None of the P. olivaceus individuals exposed to bio-floc and seawater containing waterborne nitrite concentrations of 200 mg/L for 7 days survived. Hematological parameters (hemoglobin and hematocrit) were significantly reduced by nitrite exposure. Regarding plasma components, the concentrations of glucose, glutamic oxalate transaminase (GOT), and glutamic pyruvate transaminase (GPT) increased significantly in response to nitrite exposure, whereas cholesterol concentrations significantly decreased. Stress indicators, including concentrations of plasma glucose, cortisol, and liver and gill concentrations of heat shock protein 70 (HSP70) were significantly increased by nitrite exposure. The results of the study indicate that nitrite exposure affected the hematological parameters and stress indicators of P. olivaceus raised in bio-floc and seawater, and these changes were more prominent in the P. olivaceus raised in seawater than those raised in bio-floc. Copyright © 2018 Elsevier Ltd. All rights reserved.

Migration of nitrate, nitrite, and ammonia through the municipal solid waste incinerator bottom ash layer in the simulated landfill.

PubMed

Yao, Jun; Chen, Luxi; Zhu, Huayue; Shen, Dongsheng; Qiu, Zhanhong

2017-04-01

Simulated landfill was operated for 508 days to investigate the effect of municipal solid waste incinerator (MSWI) bottom ash layer on the migration of nitrate, nitrite, and ammonia when it was used as the intermediate layer in the landfill. The result suggested that the MSWI bottom ash layer could capture the nitrate, nitrite, and ammonia from the leachate. The adsorption of the nitrate, nitrite, and ammonia on the MSWI bottom ash layer was saturated at the days 396, 34, and 97, respectively. Afterwards, the nitrogen species were desorbed from the MSWI bottom ash layer. Finally, the adsorption and desorption could reach the equilibrium. The amounts of adsorbed nitrate and nitrite on the MSWI bottom ash layer were 1685.09 and 7.48 mg, respectively, and the amount of the adsorbed and transformed ammonia was 13,773.19 mg, which was much higher than the desorbed. The water leaching test and synthetic precipitation leaching procedure (SPLP) results showed that the leachable nitrate, nitrite, and ammonia in the MSWI bottom ash were greatly increased after the landfill operation, suggesting that the adsorbed nitrogen could be finally leached out. Besides, the results also showed that MSWI bottom ash layer could affect the release of nitrate and ammonia at the initial stage of the landfill. However, it had little effect on the release of nitrite.

NITRITE REDUCTASE ACTIVITY OF NON-SYMBIOTIC HEMOGLOBINS FROM ARABIDOPSIS THALIANA†

PubMed Central

Tiso, Mauro; Tejero, Jesús; Kenney, Claire; Frizzell, Sheila; Gladwin, Mark T.

2013-01-01

Plant non-symbiotic hemoglobins possess hexa-coordinate heme geometry similar to the heme protein neuroglobin. We recently discovered that deoxygenated neuroglobin converts nitrite to nitric oxide (NO), an important signaling molecule involved in many processes in plants. We sought to determine whether Arabidopsis thaliana non-symbiotic hemoglobins class 1 and 2 (AHb1 and AHb2) might function as nitrite reductases. We found that the reaction of nitrite with deoxygenated AHb1 and AHb2 generates NO gas and iron-nitrosyl-hemoglobin species. The bimolecular rate constants for nitrite reduction to NO are 19.8 ± 3.2 and 4.9 ± 0.2 M−1s−1, at pH = 7.4 and 25°C, respectively. We determined the pH dependence of these bimolecular rate constants and found a linear correlation with the concentration of protons, indicating the requirement for one proton in the reaction. Release of free NO gas during reaction in anoxic and hypoxic (2% oxygen) conditions was confirmed by chemiluminescence detection. These results demonstrate that deoxygenated AHb1 and AHb2 reduce nitrite to form NO via a mechanism analogous to that observed for hemoglobin, myoglobin and neuroglobin. Our findings suggest that during severe hypoxia and in the anaerobic plant roots, especially in water submerged species, non-symbiotic hemoglobins provide a viable pathway for NO generation via nitrite reduction. PMID:22620259

Can the Griess Nitrite Test and a Urinary Pus Cell Count of ≥5 Cells Per Micro Litre of Urine in Pregnant Women be Used for the Screening or the Early Detection of Urinary Tract Infections in Rural India?

PubMed Central

Thakre, Sushama S.; Dhakne, Supriya S.; Thakre, Subhash B.; Thakre, Amol D.; Ughade, Suresh M.; Kale, Priya

2012-01-01

Objectives Urinary Tract Infection (UTI) is a common problem in pregnancy due to the morphological and the physiological changes that take place in the genitourinary tract during pregnancy. Screening methods may be useful, because a full bacteriological analysis could be reserved for those patients who are symptomatic or those who have positive screening test results. The exact prevalence of UTI in rural, pregnant women is unknown. The present study was undertaken to estimate the prevalence of UTI in pregnant women and for ascertaining the utility of the Griess Nitrite test and the Urinary Pus Cell Count of ≥5 cells per micro litre test for the screening or the early detection of UTI in them at primary health care clinics. Occurrence of urinary complaints was compared in UTI and non UTI women. Method We conducted a study on 300 randomly selected, pregnant women from rural areas. Urine cultures, pus-cell counts and the Griess nitrite test were used for diagnosis of UTI. The screening tests for UTI were evaluated in terms of their sensitivity, specificity, Positive Predictive Value (PPV), Negative Predictive Value (NPV) and the percentage of correctly classified. Results In the present study, the prevalence of UTI was found to be 29/300 (9.6%, 95% confidence interval 9.57-9.63). The specificities of the two screening tests were comparable (97.05% and 94.47%). Also, the negative predictive values of the two tests were almost similar (97.77% and 96.96%). The percentage of correctly classified by the Griess nitrite test and the urine pus cell count were found to be 95.33% and 92.33% respectively. The proportion of the women with various urinary complaints was significantly higher (P<0.00) in the UTI subjects as compared to that in the non-UTI subjects. Conclusion Urine culture remains the gold standard for the detection of asymptomatic bacteriuria. The Nitrite test of uncentrifuged urine was observed to be the best among the screening tests which were evaluated in terms of their efficiency and validity. PMID:23285444

HONO (nitrous acid) emissions from acidic northern soils

NASA Astrophysics Data System (ADS)

Maljanen, Marja; Yli-Pirilä, Pasi; Joutsensaari, Jorma; Sulassaari, Sirkka; Martikainen, Pertti J.

2014-05-01

The photolysis of HONO (nitrous acid) is an important source of OH radical, the key oxidizing agent in the atmosphere, contributing also to removal of atmospheric methane (CH4), the second most important greenhouse gas after carbon dioxide (CO2). There are missing sources of HONO when considering the chemical reactions in the atmosphere. Soil could be such a missing source. Emissions of HONO from soils studied in laboratory incubations have been recently reported. The soil-derived HONO has been connected to soil nitrite (NO2-) and a study with an ammonium oxidizing bacterium has shown that HONO could be produced in ammonium oxidation. Our hypothesis was that boreal acidic soils with high nitrification activity could be important sources of HONO. We selected a range of dominant northern acidic soils and showed in microcosm experiments that soils which have the highest nitrous oxide (N2O) and nitric oxide (NO) emissions (drained peatlands) also have the highest HONO production rates. The emissions of HONO are thus linked to nitrogen cycle processes. In contrast to drained peatlands, natural peatlands with high water table and boreal coniferous forests on mineral soils with low nitrification capacity had low HONO emissions. It is known that in natural peatlands with high water table and in boreal coniferous forest soils, low nitrification activity (microbial production of nitrite and nitrate) limits their N2O production. Low nitrification rate and low availability of nitrite in these soils are the likely reasons for their low HONO production rates. We studied the origin of HONO in one drained peat soil by inhibiting nitrification with acetylene. Acetylene blocked NO emissions but did not affect HONO or N2O emissions, thus ammonium oxidation is not the direct mechanism for the HONO emission in this soil. It is still an open question if HONO originates directly from some microbial process like ammonium oxidation or chemically from nitrite produced in microbial processes.

78 FR 69368 - Sodium Nitrite From Germany and the People's Republic of China: Final Results of the Expedited...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-11-19

... DEPARTMENT OF COMMERCE International Trade Administration [A-570-925; A-428-841] Sodium Nitrite... (``the Department'') initiated the first sunset reviews of the antidumping duty (``AD'') orders on sodium... Department published the AD orders on sodium nitrite from Germany and the PRC.\\1\\ On July 1, 2013, the...

Pseudomonas stutzeri Nitrite Reductase Gene Abundance in Environmental Samples Measured by Real-Time PCR

PubMed Central

Grüntzig, Verónica; Nold, Stephen C.; Zhou, Jizhong; Tiedje, James M.

2001-01-01

We used real-time PCR to quantify the denitrifying nitrite reductase gene (nirS), a functional gene of biogeochemical significance. The assay was tested in vitro and applied to environmental samples. The primer-probe set selected was specific for nirS sequences that corresponded approximately to the Pseudomonas stutzeri species. The assay was linear from 1 to 106 gene copies (r2 = 0.999). Variability at low gene concentrations did not allow detection of twofold differences in gene copy number at less than 100 copies. DNA spiking and cell-addition experiments gave predicted results, suggesting that this assay provides an accurate measure of P. stutzeri nirS abundance in environmental samples. Although P. stutzeri abundance was high in lake sediment and groundwater samples, we detected low or no abundance of this species in marine sediment samples from Puget Sound (Wash.) and from the Washington ocean margin. These results suggest that P. stutzeri may not be a dominant marine denitrifier. PMID:11157241

High temperature two component explosive

DOEpatents

Mars, James E.; Poole, Donald R.; Schmidt, Eckart W.; Wang, Charles

1981-01-01

A two component, high temperature, thermally stable explosive composition comprises a liquid or low melting oxidizer and a liquid or low melting organic fuel. The oxidizer and fuel in admixture are incapable of substantial spontaneous exothermic reaction at temperatures on the order of 475.degree. K. At temperatures on the order of 475.degree. K., the oxidizer and fuel in admixture have an activation energy of at least about 40 kcal/mol. As a result of the high activation energy, the preferred explosive compositions are nondetonable as solids at ambient temperature, and become detonable only when heated beyond the melting point. Preferable oxidizers are selected from alkali or alkaline earth metal nitrates, nitrites, perchlorates, and/or mixtures thereof. Preferred fuels are organic compounds having polar hydrophilic groups. The most preferred fuels are guanidinium nitrate, acetamide and mixtures of the two. Most preferred oxidizers are eutectic mixtures of lithium nitrate, potassium nitrate and sodium nitrate, of sodium nitrite, sodium nitrate and potassium nitrate, and of potassium nitrate, calcium nitrate and sodium nitrate.

Oral Microbiome and Nitric Oxide: the Missing Link in the Management of Blood Pressure.

PubMed

Bryan, Nathan S; Tribble, Gena; Angelov, Nikola

2017-04-01

Having high blood pressure puts you at risk for heart disease and stroke, which are leading causes of death in the USA and worldwide. One out of every three Americans has hypertension, and it is estimated that despite aggressive treatment with medications, only about half of those medicated have managed blood pressure. Recent discoveries of the oral microbiome that reduces inorganic nitrate to nitrite and nitric oxide provide a new therapeutic target for the management of hypertension. The presence or absence of select and specific bacteria may determine steady-state blood pressure levels. Eradication of oral bacteria through antiseptic mouthwash or overuse of antibiotics causes blood pressure to increase. Allowing recolonization of nitrate- and nitrite-reducing bacteria can normalize blood pressure. This review will provide evidence of the link between oral microbiota and the production of nitric oxide and regulation of systemic blood pressure. Management of systemic hypertension through maintenance of the oral microbiome is a completely new paradigm in cardiovascular medicine.

Portable paper-based device for quantitative colorimetric assays relying on light reflectance principle.

PubMed

Li, Bowei; Fu, Longwen; Zhang, Wei; Feng, Weiwei; Chen, Lingxin

2014-04-01

This paper presents a novel paper-based analytical device based on the colorimetric paper assays through its light reflectance. The device is portable, low cost (<20 dollars), and lightweight (only 176 g) that is available to assess the cost-effectiveness and appropriateness of the original health care or on-site detection information. Based on the light reflectance principle, the signal can be obtained directly, stably and user-friendly in our device. We demonstrated the utility and broad applicability of this technique with measurements of different biological and pollution target samples (BSA, glucose, Fe, and nitrite). Moreover, the real samples of Fe (II) and nitrite in the local tap water were successfully analyzed, and compared with the standard UV absorption method, the quantitative results showed good performance, reproducibility, and reliability. This device could provide quantitative information very conveniently and show great potential to broad fields of resource-limited analysis, medical diagnostics, and on-site environmental detection. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Plasma nitrate and nitrite are increased by a high nitrate supplement, but not by high nitrate foods in older adults

PubMed Central

Miller, Gary D.; Marsh, Anthony P.; Dove, Robin W.; Beavers, Daniel; Presley, Tennille; Helms, Christine; Bechtold, Erika; King, S. Bruce; Kim-Shapiro, Daniel

2012-01-01

Little is known about the effect of dietary nitrate on the nitrate/nitrite/NO (nitric oxide) cycle in older adults. We examined the effect of a 3-day control diet vs. high nitrate diet, with and without a high nitrate supplement (beetroot juice), on plasma nitrate and nitrite kinetics, and blood pressure using a randomized four period cross-over controlled design. We hypothesized that the high nitrate diet would show higher levels of plasma nitrate/nitrite and blood pressure compared to the control diet, which would be potentiated by the supplement. Participants were eight normotensive older men and women (5 female, 3 male, 72.5±4.7 yrs) with no overt disease or medications that affect NO metabolism. Plasma nitrate and nitrite levels and blood pressure were measured prior to and hourly for 3 hours after each meal. The mean daily changes in plasma nitrate and nitrite were significantly different from baseline for both control diet+supplement (p<0.001 and =0.017 for nitrate and nitrite, respectively) and high nitrate diet+supplement (p=0.001 and 0.002), but not for control diet (p=0.713 and 0.741) or high nitrate diet (p=0.852 and 0.500). Blood pressure decreased from the morning baseline measure to the three 2 hr post-meal follow-up time-points for all treatments, but there was no main effect for treatment. In healthy older adults, a high nitrate supplement consumed at breakfast elevated plasma nitrate and nitrite levels throughout the day. This observation may have practical utility for the timing of intake of a nitrate supplement with physical activity for older adults with vascular dysfunction. PMID:22464802

NADPH-cytochrome P450 reductase-mediated denitration reaction of 2,4,6-trinitrotoluene to yield nitrite in mammals.

PubMed

Shinkai, Yasuhiro; Nishihara, Yuya; Amamiya, Masahiro; Wakayama, Toshihiko; Li, Song; Kikuchi, Tomohiro; Nakai, Yumi; Shimojo, Nobuhiro; Kumagai, Yoshito

2016-02-01

While the biodegradation of 2,4,6-trinitrotoluene (TNT) via the release of nitrite is well established, mechanistic details of the reaction in mammals are unknown. To address this issue, we attempted to identify the enzyme from rat liver responsible for the production of nitrite from TNT. A NADPH-cytochrome P450 reductase (P450R) was isolated and identified from rat liver microsomes as the enzyme responsible for not only the release of nitrite from TNT but also formation of superoxide and 4-hydroxyamino-2,6-dinitrotoluene (4-HADNT) under aerobic conditions. In this context, reactive oxygen species generated during P450R-catalyzed TNT reduction were found to be, at least in part, a mediator for the production of 4-HADNT from TNT via formation of 4-nitroso-2,6-dinitrotoluene. P450R did not catalyze the formation of the hydride-Meisenheimer complex (H(-)-TNT) that is thought to be an intermediate for nitrite release from TNT. Furthermore, in a time-course experiment, 4-HADNT formation reached a plateau level and then declined during the reaction between TNT and P450R with NADPH, while the release of nitrite was subjected to a lag period. Notably, the produced 4-HADNT can react with the parent compound TNT to produce nitrite and dimerized products via formation of a Janovsky complex. Our results demonstrate for the first time that P450R-mediated release of nitrite from TNT results from the process of chemical interaction of TNT and its 4-electron reduction metabolite 4-HADNT. Copyright © 2015 Elsevier Inc. All rights reserved.

Intracellular pH homeostasis plays a role in the tolerance of Debaryomyces hansenii and Candida zeylanoides to acidified nitrite.

PubMed

Mortensen, Henrik Dam; Jacobsen, Tomas; Koch, Anette Granly; Arneborg, Nils

2008-08-01

The effects of acidified-nitrite stress on the growth initiation and intracellular pH (pH(i)) of individual cells of Debaryomyces hansenii and Candida zeylanoides were investigated. Our results show that 200 microg/ml of nitrite caused pronounced growth inhibition and intracellular acidification of D. hansenii at an external pH (pH(ex)) value of 4.5 but did not at pH(ex) 5.5. These results indicate that nitrous acid as such plays an important role in the antifungal effect of acidified nitrite. Furthermore, both yeast species experienced severe growth inhibition and a pH(i) decrease at pH(ex) 4.5, suggesting that at least some of the antifungal effects of acidified nitrite may be due to intracellular acidification. For C. zeylanoides, this phenomenon could be explained in part by the uncoupling effect of energy generation from growth. Debaryomyces hansenii was more tolerant to acidified nitrite at pH(ex) 5.5 than C. zeylanoides, as determined by the rate of growth initiation. In combination with the fact that D. hansenii was able to maintain pH(i) homeostasis at pH(ex) 5.5 but C. zeylanoides was not, our results suggest that the ability to maintain pH(i) homeostasis plays a role in the acidified-nitrite tolerance of D. hansenii and C. zeylanoides. Possible mechanisms underlying the different abilities of the two yeast species to maintain their pH(i) homeostasis during acidified-nitrite stress, comprising the intracellular buffer capacity and the plasma membrane ATPase activity, were investigated, but none of these mechanisms could explain the difference.

Thyroid cancer risk and dietary nitrate and nitrite intake in the Shanghai women's health study.

PubMed

Aschebrook-Kilfoy, Briseis; Shu, Xiao-Ou; Gao, Yu-Tang; Ji, Bu-Tian; Yang, Gong; Li, Hong Lan; Rothman, Nathaniel; Chow, Wong-Ho; Zheng, Wei; Ward, Mary H

2013-02-15

Nitrate and nitrite are precursors in the endogenous formation of N-nitroso compounds and nitrate can disrupt thyroid homeostasis by inhibiting iodide uptake. We evaluated nitrate and nitrite intake and risk of thyroid cancer in the Shanghai Women's Health Study that included 73,317 women, aged 40-70 years enrolled in 1996-2000. Dietary intake was assessed at baseline using a food frequency questionnaire. During approximately 11 years of follow-up, 164 incident thyroid cancer cases with complete dietary information were identified. We used Cox proportional hazards regression to estimate relative risks (RRs). We determined the nitrate and nitrite contents of foods using values from the published literature and focusing on regional values for Chinese foods. Nitrate intake was not associated with thyroid cancer risk [RR(Q4) = 0.93; 95% confidence interval (CI): 0.42-2.07; p for trend = 0.40]. Compared to the lowest quartile, women with the highest dietary nitrite intake had about a twofold risk of thyroid cancer (RR(Q4) = 2.05; 95%CI: 1.20-3.51), but there was not a monotonic trend with increasing intake (p for trend = 0.36). The trend with increasing nitrite intake from animal sources was significant (p for trend = 0.02) and was stronger for nitrite from processed meats (RR(Q4) = 1.96; 95%CI: 1.28-2.99; p for trend < 0.01). Although we did not observe an association for nitrate as hypothesized, our results suggest that women consuming higher levels of nitrite from animal sources, particularly from processed meat, may have an increased risk of thyroid cancer. Copyright © 2012 UICC.

Chemical reactivity of nitrates and nitrites towards TBP and potassium nickel ferrocyanide between 30 and 300 deg

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lambertin, D.; Chartier, D.; Joussot-Dubien, C.

2007-07-01

Since the late sixties, bitumen has been widely used by the nuclear industry as a matrix for the immobilization of low- and intermediate level radioactive waste originating mainly from the nuclear activities: precipitation or evaporator concentrates, ion exchange resins, incinerator ashes, and filter materials. Depending on bitumen and operating conditions, bituminization of radioactive waste can be operated between 130 and 180 deg. C, so chemical reaction can be induced with nitrate or nitrite towards elements contained in waste (TPB, potassium nickel ferrocyanide and cobalt compound) and bitumen. These reactions are mainly exothermic this is the reason why the enthalpy reactionmore » and their temperature of initiation have to be determined independently of their concentration in waste. In this work, we have studied by Calvet Calorimetry at 0.1 deg. C/min heating rates, the behaviour of chemical elements especially oxido-reduction couples that can react at a temperature range 100- 300 deg. C (Nitrate/PPFeNi, Nitrite/PPFeNi, Nitrate/TBP, Nitrite/TBP, Nitrate/bitumen and Nitrite/bitumen). The initial temperature reaction of nitrates or nitrites towards potassium nickel ferrocyanide (PPFeNi) has been studied and is equal respectively to 225 deg. C and 175 deg. C. Because of the large scale temperature reaction of nitrate and PPFeNi, enthalpy reaction can not be calculated, although enthalpy reaction of nitrite and PPFeNi is equal to 270 kJ/mol of nitrite. Sodium Nitrate and TBP behaviour has been investigated, and an exothermic reaction at 135 deg. C until 250 deg. C is evidenced. The exothermic energy reaction is a function of TBP concentration and the enthalpy reaction has been determined. (authors)« less

Effect of temperature and dissolved oxygen on biological nitrification at high ammonia concentrations.

PubMed

Weon, S Y; Lee, S I; Koopman, B

2004-11-01

Effect of temperature and dissolved oxygen concentration on nitrification rate were investigated with enrichment cultures of nitrifying bacteria. Values of specific nitrite oxidation rate in the absence of ammonia were 2.9-12 times higher than maximum specific ammonia oxidation rates at the same temperatures. The presence of high ammonia levels reversed this relationship, causing maximum specific nitrite oxidation rates to fall to 19 to 45% as high as maximum specific ammonia oxidation rates. This result suggests that nitrification at high ammonia levels will invariably result in nitrite accumulation. The K(O2) for nitrite oxidation in the presence of high ammonia levels was higher than the K(O2) for ammonia oxidation when temperature exceeded 18 degrees C, whereas the opposite was true at lower temperatures. These results indicate that low oxygen tensions will exacerbate nitrite accumulation when water temperature is high.

Very early reaction intermediates detected by microsecond time scale kinetics of cytochrome cd1-catalyzed reduction of nitrite.

PubMed

Sam, Katharine A; Strampraad, Marc J F; de Vries, Simon; Ferguson, Stuart J

2008-10-10

Paracoccus pantotrophus cytochrome cd(1) is a nitrite reductase found in the periplasm of many denitrifying bacteria. It catalyzes the reduction of nitrite to nitric oxide during the denitrification part of the biological nitrogen cycle. Previous studies of early millisecond intermediates in the nitrite reduction reaction have shown, by comparison with pH 7.0, that at the optimum pH, approximately pH 6, the earliest intermediates were lost in the dead time of the instrument. Access to early time points (approximately 100 micros) through use of an ultra-rapid mixing device has identified a spectroscopically novel intermediate, assigned as the Michaelis complex, formed from reaction of fully reduced enzyme with nitrite. Spectroscopic observation of the subsequent transformation of this species has provided data that demand reappraisal of the general belief that the two subunits of the enzyme function independently.

Changes of sodium nitrate, nitrite, and N-nitrosodiethylamine during in vitro human digestion.

PubMed

Kim, Hyeong Sang; Hur, Sun Jin

2017-06-15

This study aimed to determine the changes in sodium nitrate, sodium nitrite, and N-nitrosodiethylamine (NDEA) during in vitro human digestion, and the effect of enterobacteria on the changes in these compounds. The concentrations of nitrate, nitrite, and NDEA were significantly reduced from 150, 150, and 1ppm to 42.8, 63.2, and 0.85ppm, respectively, during in vitro human digestion (p<0.05). The enterobacteria Escherichia coli and Lactobacillus casei reduced the amount of these compounds present during in vitro human digestion. This study is the first to report that E. coli can dramatically reduce the amount of nitrite during in vitro human digestion and this may be due to the effect of nitrite reductase present in E. coli. We therefore conclude that the amounts of potentially harmful substances and their toxicity can be decreased during human digestion. Copyright © 2017 Elsevier Ltd. All rights reserved.

Combined effects of gamma radiation doses and sodium nitrite content on the lipid oxidation and color of mortadella.

PubMed

Dutra, Monalisa Pereira; Cardoso, Giselle Pereira; Fontes, Paulo Rogério; Silva, Douglas Roberto Guimarães; Pereira, Marcio Tadeu; Ramos, Alcinéia de Lemos Souza; Ramos, Eduardo Mendes

2017-12-15

The effects of different doses of gamma radiation (0-20kGy) on the color and lipid oxidation of mortadella prepared with increasing nitrite levels (0-300ppm) were evaluated using a central composite rotatable design. Higher radiation doses increased the redox potential, promoted the lipid oxidation and elevating the hue color of the mortadellas. Nevertheless, higher addition of sodium nitrite elevated the residual nitrite content, reduced the lipid oxidation and promoted the increase of redness and the reduce of hue color of the mortadellas, regardless of the radiation dose applied. Nitrite addition had a greater effect than irradiation on the quality parameters evaluated, and even at low levels (∼75ppm), its use decreased the deleterious effects of irradiation at doses as high as 20kGy. Copyright © 2017 Elsevier Ltd. All rights reserved.

An indigenously developed nitrite kit to aid in the diagnosis of urinary tract infection.

PubMed

Sood, S; Upadhyaya, P; Kapil, A; Lodha, R; Jain, Y; Bagga, A

1999-09-01

To evaluate the utility of an indigenously developed nitrite kit for the rapid diagnosis of urinary tract infection (UTI) METHODS: 1018 urine specimens were collected from all cases where there was clinical suspicion of UTI. Samples were cultured as per standard microbiological protocol. Presence of nitrites was indicated by the development of purple color on addition of color developing solution and compared with the set of graded positive and negative controls also provided in the Kit. The results of the nitrite kit were compared with the semi-quantitative urine culture as the gold standard. The sensitivity, specificity, positive predictive and negative predictive values were 47%, 87%, 31% and 93%, respectively. Nitrite kit as a screening test can decrease the work load in the clinical bacteriology laboratory. More importantly in a field set up that is devoid of culture facilities, it can be used to correctly predict the absence of UTI.

Dissimilatory reduction of nitrate and nitrite in the bovine rumen: nitrous oxide production and effect of acetylene.

PubMed

Kaspar, H F; Tiedje, J M

1981-03-01

15N tracer methods and gas chromatography coupled to an electron capture detector were used to investigate dissimilatory reduction of nitrate and nitrite by the rumen microbiota of a fistulated cow. Ammonium was the only 15N-labeled end product of quantitative significance. Only traces of nitrous oxide were detected as a product of nitrate reduction; but in experiments with nitrite, up to 0.3% of the added nitrogen accumulated as nitrous oxide, but it was not further reduced. Furthermore, when 13NO3- was incubated with rumen microbiota virtually no [13N]N2 was produced. Acetylene partially inhibited the reduction of nitrite to ammonium as well as the formation of nitrous oxide. It is suggested that in the rumen ecosystem nitrous oxide is a byproduct of dissimilatory nitrite reduction to ammonium rather than a product of denitrification and that the latter process is absent from the rumen habitat.

Molecular identification of potential denitrifying bacteria and use of D-optimal mixture experimental design for the optimization of denitrification process.

PubMed

Ben Taheur, Fadia; Fdhila, Kais; Elabed, Hamouda; Bouguerra, Amel; Kouidhi, Bochra; Bakhrouf, Amina; Chaieb, Kamel

2016-04-01

Three bacterial strains (TE1, TD3 and FB2) were isolated from date palm (degla), pistachio and barley. The presence of nitrate reductase (narG) and nitrite reductase (nirS and nirK) genes in the selected strains was detected by PCR technique. Molecular identification based on 16S rDNA sequencing method was applied to identify positive strains. In addition, the D-optimal mixture experimental design was used to optimize the optimal formulation of probiotic bacteria for denitrification process. Strains harboring denitrification genes were identified as: TE1, Agrococcus sp LN828197; TD3, Cronobacter sakazakii LN828198 and FB2, Pedicoccus pentosaceus LN828199. PCR results revealed that all strains carried the nirS gene. However only C. sakazakii LN828198 and Agrococcus sp LN828197 harbored the nirK and the narG genes respectively. Moreover, the studied bacteria were able to form biofilm on abiotic surfaces with different degree. Process optimization showed that the most significant reduction of nitrate was 100% with 14.98% of COD consumption and 5.57 mg/l nitrite accumulation. Meanwhile, the response values were optimized and showed that the most optimal combination was 78.79% of C. sakazakii LN828198 (curve value), 21.21% of P. pentosaceus LN828199 (curve value) and absence (0%) of Agrococcus sp LN828197 (curve value). Copyright © 2016 Elsevier Ltd. All rights reserved.

A Simple Automated Method for the Determination of Nitrate and Nitrite in Infant Formula and Milk Powder Using Sequential Injection Analysis

PubMed Central

Pistón, Mariela; Mollo, Alicia; Knochen, Moisés

2011-01-01

A fast and efficient automated method using a sequential injection analysis (SIA) system, based on the Griess, reaction was developed for the determination of nitrate and nitrite in infant formulas and milk powder. The system enables to mix a measured amount of sample (previously constituted in the liquid form and deproteinized) with the chromogenic reagent to produce a colored substance whose absorbance was recorded. For nitrate determination, an on-line prereduction step was added by passing the sample through a Cd minicolumn. The system was controlled from a PC by means of a user-friendly program. Figures of merit include linearity (r2 > 0.999 for both analytes), limits of detection (0.32 mg kg−1 NO3-N, and 0.05 mg kg−1 NO2-N), and precision (sr%) 0.8–3.0. Results were statistically in good agreement with those obtained with the reference ISO-IDF method. The sampling frequency was 30 hour−1 (nitrate) and 80 hour−1 (nitrite) when performed separately. PMID:21960750