WorldWideScience

Sample records for amyl nitrite

  1. Near-fatal methemoglobinemia after recreational inhalation of amyl nitrite aerosolized with a compressed gas blower.

    Science.gov (United States)

    Lin, Chih-Hao; Fang, Cheng-Chung; Lee, Chien-Chang; Ko, Patrick Chow-In; Chen, Wen-Jone

    2005-11-01

    Adverse effects associated with recreational inhalation of nitrites are usually mild and rarely life-threatening. We report a rare case of near-fatal methemoglobinemia after inhalation of amyl nitrite after aerosolizing the liquid using a compressed gas blower designed to clean photographic equipment that employed hydrofluoroalkane-134a as a propellant. A 31-year-old previously healthy male became dyspneic and fainted soon after the recreational inhalation of amyl nitrite aerosolized using a compressed gas blower. He was brought to the emergency department with severe cyanotic appearance and profound shock. Oxygen saturation was 82%, unresponsive to oxygen supply. His methemoglobin blood level was 52.2%. After 100 mg of methylene blue (2 mg/kg body weight) was administered intravenously, he recovered consciousness, and dyspnea and cyanosis subsided gradually. This case illustrates the extraordinary hazard of the use of a compressed gas blower in the recreational inhalation of nitrites. Prompt recognition and rapid antidotal treatment may adequately correct near-fatal overdose associated with recreational use of amyl nitrite.

  2. Popping and snorting volatile nitrites: a current fad for getting high.

    Science.gov (United States)

    Sigell, L T; Kapp, F T; Fusaro, G A; Nelson, E D; Falck, R S

    1978-10-01

    In certain social circles a variety of volatile nitrites are being used extensively to expand creativity, stimulate music appreciation, promote a sense of abandon in dancing, and intensify sexual experience. Soon after amyl nitrite (the prototype of this group) became a prescription drug, legally produced substitutes appeared and were sold as room odorizers. Analyses of eight of these substitutes showed them to contain isomers of butyl or amyl alcohol and a corresponding nitrite. The authors describe the context of use of these products and their desired and adverse effects.

  3. Mutagenicity of some alkyl nitrites used as recreational drugs

    Energy Technology Data Exchange (ETDEWEB)

    Dunkel, V.C.; Cameron, T.P. (National Institute of Health, Bethesda (USA)); Rogers-Back, A.M.; Lawlor, T.E.; Harbell, J.W. (Microbiological Associates Inc., Rockville, MD (USA))

    1989-01-01

    When the AIDS epidemic was in its earliest stages, and prior to identification of HIV as the etiological factor, the use of volatile nitrites by the male homosexual community to enhance sexual activities appeared to have a significant role in this disease. Preliminary observations indicated that that portion of the male homosexual community which developed Kaposi's sarcoma were also heavy nitrite users. These nitrites had been demonstrated to be mutagenic in bacteria and thus it was postulated that they could be responsible for the appearance of the sarcoma. To evaluate further the genotoxic activity of these chemicals, six nitrites, including those most commonly used by homosexuals for sexual gratification, were selected for testing in the mouse lymphoma TK {plus minus} and Salmonell typhimurium mutagenicity assays. One chemical, n-amyl nitrite, was negative in the mouse lymphoma assay, while the other five chemicals, n-butyl, isobutyl, iso-amyl, sec-butyl, and n-propyl nitrite, were positive. All six compounds were positive in the Salmonella assay. The mutagenic and known toxic effects of these chemicals remain a concern because a large population of teenagers and young adults continue to abuse these substances.

  4. Study on Extraction Performance of Tri-iso-amyl Phosphate

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The distribution performance of HNO3, Pu(Ⅲ ), Pu(Ⅳ) and Np(Ⅳ) in the two phase system of Tri-iso-Amyl Phosphate(TiAP) and aqueous, the influence of the concentration of extractant, nitric acid and Al(NO3)3 on the distribution ratio of Pu(Ⅲ ),

  5. 40 CFR 721.2920 - tert-Amyl peroxy alkylene ester (generic name).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false tert-Amyl peroxy alkylene ester... Specific Chemical Substances § 721.2920 tert-Amyl peroxy alkylene ester (generic name). (a) Chemical... alkylene ester (PMN P-85-1180) is subject to reporting under this section for the significant new...

  6. 21 CFR 181.34 - Sodium nitrite and potassium nitrite.

    Science.gov (United States)

    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... fixatives and preservative agents, with or without sodium or potassium nitrate, in the curing of red...

  7. IRIS Toxicological Review and Summary Documents for Tertiary Amyl Ethyl Ether (Taee)

    Science.gov (United States)

    This is EPA's first assessment of the noncancer health effects and carcinogenic potential of tertiary amyl ethyl ether (TAEE). The IRIS program is preparing an assessment that will incorporate health effects information available for TAEE, and current risk assessment methods. T...

  8. Kinetics Studies on Esterification Reaction of Acetic acid with Iso-amyl Alcohol over Ion Exchange Resin as Catalysts

    Directory of Open Access Journals (Sweden)

    Bhaskar D. Kulkarni

    2014-01-01

    Full Text Available The low molecular weight organic esters have pleasing smell and are found in applications in the food industry for synthetic essence and perfume. Esterification reactions are ubiquitous reactions especially in pharmaceutical, perfumery and polymer industries, wherein; both heterogeneous and homogeneous catalysts have been extensively used. Iso-amyl acetate (or Iso-pentyl acetate is often called as banana oil, since it has the recognizable odor of this fruit. Iso-amyl acetate is synthesized by esterification of acetic acid with iso-amyl alcohol. (Eq.1. Since the equilibrium does not help the formation of the ester, it must be shifted to the right, in favor of the product, by using a surplus of one of the starting materials. Iso-amyl acetate is a kind of flavor reagent with fruit taste. The use of H2SO4 often originates the problems such as corrosion for equipments and pollution for environment.

  9. ADVANCED TECHNOLOGY WASTEWATER TREATMENT OF NITRITE IONS

    Directory of Open Access Journals (Sweden)

    E.G. Morozov

    2012-06-01

    Full Text Available The main reason for high concentration of nitrite ions in water is the existence of sources of industrial and agricultural pollution. Contamination of drinking water, juices, wine and other liquids of nitrite ions as a result of improper use of nitrogen fertilizers has an adverse effect on living organism, because under the influence of enzymes nitrite ions in living organisms form high carcinogenic nitrosamines, and the interaction of nitrite ions from blood hemoglobin causes such toxicity that leads to disease cyanosis [1]. Therefore removal of nitrite ions from water has received increased attention. The paper discusses an innovative wastewater treatment technology from the nitrite ion with hypochlorite produced during electrolysis.

  10. ADVANCED TECHNOLOGY WASTEWATER TREATMENT OF NITRITE IONS

    OpenAIRE

    E. G. Morozov; V.M. Nikol`skii; T.V. Saprunova; A.A. Yakovlev

    2012-01-01

    The main reason for high concentration of nitrite ions in water is the existence of sources of industrial and agricultural pollution. Contamination of drinking water, juices, wine and other liquids of nitrite ions as a result of improper use of nitrogen fertilizers has an adverse effect on living organism, because under the influence of enzymes nitrite ions in living organisms form high carcinogenic nitrosamines, and the interaction of nitrite ions from blood hemoglobin causes such toxicity t...

  11. 21 CFR 172.175 - Sodium nitrite.

    Science.gov (United States)

    2010-04-01

    ... Preservatives § 172.175 Sodium nitrite. The food additive sodium nitrite may be safely used in or on specified... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Sodium nitrite. 172.175 Section 172.175 Food and... preservative and color fixative, with sodium nitrate, in meat-curing preparations for the home curing of...

  12. Drug: D00517 [KEGG MEDICUS

    Lifescience Database Archive (English)

    Full Text Available ism 39 Other agents affecting metabolism 392 Antidotes 3929 Others D00517 Amyl nitrite (JP16/USP) Anatomical...L OTHER THERAPEUTIC PRODUCTS V03AB Antidotes V03AB22 Amyl nitrite D00517 Amyl nit

  13. Isolation and Identification of Nitrite- oxidizing Bacteria

    Institute of Scientific and Technical Information of China (English)

    Yulong; CHEN; Wenyong; TAN; Da; YANG

    2015-01-01

    In order to select the strain that can degrade nitrite,we use the screening plate with nitrite as the sole nitrogen source to select the strain with ability to degrade nitrite,and get a strain with nitrite degrading capacity from the silt of shrimp farming pond in Hepu City,Guangxi Zhuang Autonomous Region. By identifying the strain from colony morphology,physiological and biochemical characteristics and 16 S r RNA sequence,we finally get a bacteria strain that can degrade nitrite,and this strain can grow well on the culture medium with nitrite concentration of 2 g / L. Based on morphology,nitrogen source requirements and evolutionary tree analysis of the above 16 S r RNA sequence,it is found that this strain belongs to Pannonibacter phragmitetus. According to the screening location,it is named HPPP007 strain.

  14. Screening for occupational vitiligo in workers exposed to hydroquinone monomethyl ether and to paratertiary-amyl-phenol

    Energy Technology Data Exchange (ETDEWEB)

    O' Sullivan, J.J.; Stevenson, C.J.

    1981-11-01

    Two men reported previously with vitiligo after occupational exposure to hydroquinone monomethyl ether (HMME) have been reviewed after eight years. Repigmentation of significant degree was found in one man and of limited degree in the other. One hundred and sixty-nine men in the same works have been screened with Wood's light for evidence of vitiligo. No cases were found in the 148 men exposed to HMME (colleagues who screened 100 men exposed to HMME in two other factories also found no case) or in the 129 who had been exposed to paratertiary-amyl-phenol. Loss of light reflection on Wood's light examination was observed in 13 men due to scars or to other skin disorders.

  15. ETBE (ethyl tert butyl ether) and TAME (tert amyl methyl ether) affect microbial community structure and function in soils.

    Science.gov (United States)

    Bartling, Johanna; Esperschütz, Jürgen; Wilke, Berndt-Michael; Schloter, Michael

    2011-03-15

    Ethyl tert butyl ether (ETBE) and tert amyl methyl ether (TAME) are oxygenates used in gasoline in order to reduce emissions from vehicles. The present study investigated their impact on a soil microflora that never was exposed to any contamination before. Therefore, soil was artificially contaminated and incubated over 6 weeks. Substrate induced respiration (SIR) measurements and phospholipid fatty acid (PLFA) analysis indicated shifts in both, microbial function and structure during incubation. The results showed an activation of microbial respiration in the presence of ETBE and TAME, suggesting biodegradation by the microflora. Furthermore, PLFA concentrations decreased in the presence of ETBE and TAME and Gram-positive bacteria became more dominant in the microbial community.

  16. 21 CFR 573.700 - Sodium nitrite.

    Science.gov (United States)

    2010-04-01

    ... Listing § 573.700 Sodium nitrite. Sodium nitrite may be safely used in canned pet food containing meat and fish in accordance with the following prescribed conditions: (a) It is used or intended for use alone as a preservative and color fixative in canned pet food containing fish, meat, and fish and...

  17. Nitrite disrupts multiple physiological functions in aquatic animals

    DEFF Research Database (Denmark)

    Jensen, Frank Bo

    2003-01-01

    nitrite-induced vasodilation (possibly via nitric oxide generated from nitrite) that is countered by increased cardiac pumping to re-establish blood pressure. Nitrite can form and/or mimic nitric oxide and thereby interfere with processes regulated by this local hormone. Steroid hormone synthesis may...... be inhibited, while changes in ammonia and urea levels and excretion rates reflect an influence of nitrite on nitrogen metabolism. Detoxification of nitrite occurs via endogenous oxidation to nitrate, and elimination of nitrite takes place both via gills and urine. The susceptibility to nitrite varies between...

  18. Nitrite complexes of uranium and thorium.

    Science.gov (United States)

    Dulong, Florian; Pouessel, Jacky; Thuéry, Pierre; Berthet, Jean-Claude; Ephritikhine, Michel; Cantat, Thibault

    2013-03-25

    The first examples of inorganic nitrite complexes of the natural actinides are described, including the structures of the homoleptic thorium(IV) [PPh(4)](2)[Th(NO(2))(6)] and the uranyl(VI) [PPh(4)](2)[UO(2)(NO(2))(4)] complexes; the nitrite ligand can adopt two different coordination modes in the coordination sphere of the uranyl ion and is unstable towards reduction.

  19. Sensing nitrite through a pseudoazurin-nitrite reductase electron transfer relay

    NARCIS (Netherlands)

    Astier, Y; Canters, GW; Davis, JJ; Hill, HAO; Verbeet, MP; Wijma, HJ

    2005-01-01

    Nitrite is converted to nitric oxide by haem or copper-containing enzymes in denitrifying bacteria during the process of denitrification. In designing an efficient biosensor, this enzymic turnover must be quantitatively assessed. The enzyme nitrite reductase from Alcaligenes faecalis contains a redo

  20. pH dependence of copper geometry, reduction potential, and nitrite affinity in nitrite reductase.

    NARCIS (Netherlands)

    Jacobson, F.; Pistorius, A.M.A.; Farkas, D.; Grip, W.J. de; Hansson, O.; Sjolin, L.; Neutze, R.

    2007-01-01

    Many properties of copper-containing nitrite reductase are pH-dependent, such as gene expression, enzyme activity, and substrate affinity. Here we use x-ray diffraction to investigate the structural basis for the pH dependence of activity and nitrite affinity by examining the type 2 copper site and

  1. N-butyl-2-cyanoacrylate, iso-amyl-2-cyanoacrylate andhypertonic glucose with 72% chromated glycerin in gastricvarices

    Institute of Scientific and Technical Information of China (English)

    Reda Elwakil; Mohamed Fawzy Montasser; Sara M Abdelhakam; Wesam A Ibrahim

    2015-01-01

    cyanoacrylate and a mixture of 72% chromated glycerinwith hypertonic glucose solution in management ofgastric varices.METHODS: Ninety patients with gastric varicespresented to Endoscopy Unit of Ain Shams UniversityHospital were included. They were randomly allocatedinto three groups; each group included 30 patients treatedwith intravariceal sclerosant injections in biweeklysessions till complete obturation of gastric varices;Group I (n-butyl-2-cyanoacrylate; Histoacryl?), GroupII (iso-amyl-2-cyanoacrylate; Amcrylate?) and GroupIII (mixture of 72% chromated glycerin; Scleremo?with glucose solution 25%). All the procedures wereperformed electively without active bleeding. Recruitedpatients were followed up for 3 mo.RESULTS: 26% of Scleremo group had bleeding duringpuncture vs 3.3% in each of the other two groups withsignificant difference, (P 〈 0.05). None of Scleremogroup had needle obstruction vs 13.3% in each of theother two groups with no significant difference, (P 〉0.05). Rebleeding occurred in 13.3% of Histoacryl andAmcrylate groups vs 0% in Scleremo group with nosignificant difference. The in hospital mortality was 6.6%in both Histoacryl and Amcrylate groups, while it was0% in Scleremo group with no significant difference. Inthe first and second sessions, the amount of Scleremoneeded for obturation was significantly high, while the amount of Histoacryl was significantly low. Scleremo was the less costly of the two treatments. CONCLUSION: All used sclerosant substances showed efficacy and success in management of gastric varices with no significant differences except in total amount,cost and bleeding during puncture.

  2. TAME (tertiary-amyl-methyl ether) gasoline additive production process development; Desenvolvimento do processo de producao de TAME-aditivo para gasolina

    Energy Technology Data Exchange (ETDEWEB)

    Lovisi, Humberto [Petroflex Industria e Comercio S.A., Duqye de Caxias, RJ (Brazil); Piccoli, Ricardo [COPESUL, Companhia Petroquimica do Sul, Triunfo, RS (Brazil)

    1992-12-31

    PETROFLEX and COPESUL jointly developed a TAME production process. Tertiary-amyl-methyl ether (TAME) is obtained by the methoxylation of isoamylenes (2-methyl-1-butene and 2-methyl-2-butene) in a C{sub s} cut over a sulfonic acid resin. Process was developed on the basis of pilot plant and batch experiments. A simplified process flow-sheet and pilot plant data are presented. Isoamylenes conversions higher than 70% were achieved with low by-products formation. (author) 22 refs., 2 figs., 2 tabs.

  3. Hypoxia tolerance, nitric oxide, and nitrite

    DEFF Research Database (Denmark)

    Fago, Angela; Jensen, Frank Bo

    2015-01-01

    Among vertebrates able to tolerate periods of oxygen deprivation, the painted and red-eared slider turtles (Chrysemys picta and Trachemys scripta) and the crucian carp (Carassius carassius) are the most extreme and can survive even months of total lack of oxygen during winter. The key to hypoxia ...... of NO and nitrite signaling in the adaptive response to hypoxia in vertebrate animals....... survival resides in concerted physiological responses, including strong metabolic depression, protection against oxidative damage and – in air breathing animals - redistribution of blood flow. Each of these responses is known to be tightly regulated by nitric oxide (NO) and during hypoxia by its metabolite...... nitrite. The aim of this review is to highlight recent work illustrating the widespread roles of NO and nitrite in the tolerance to extreme oxygen deprivation, in particular in the red-eared slider turtle and crucian carp, but also in diving marine mammals. The emerging picture underscores the importance...

  4. Platelet inhibition by nitrite is dependent on erythrocytes and deoxygenation.

    Directory of Open Access Journals (Sweden)

    Sirada Srihirun

    Full Text Available BACKGROUND: Nitrite is a nitric oxide (NO metabolite in tissues and blood, which can be converted to NO under hypoxia to facilitate tissue perfusion. Although nitrite is known to cause vasodilation following its reduction to NO, the effect of nitrite on platelet activity remains unclear. In this study, the effect of nitrite and nitrite+erythrocytes, with and without deoxygenation, on platelet activity was investigated. METHODOLOGY/FINDING: Platelet aggregation was studied in platelet-rich plasma (PRP and PRP+erythrocytes by turbidimetric and impedance aggregometry, respectively. In PRP, DEANONOate inhibited platelet aggregation induced by ADP while nitrite had no effect on platelets. In PRP+erythrocytes, the inhibitory effect of DEANONOate on platelets decreased whereas nitrite at physiologic concentration (0.1 µM inhibited platelet aggregation and ATP release. The effect of nitrite+erythrocytes on platelets was abrogated by C-PTIO (a membrane-impermeable NO scavenger, suggesting an NO-mediated action. Furthermore, deoxygenation enhanced the effect of nitrite as observed from a decrease of P-selectin expression and increase of the cGMP levels in platelets. The ADP-induced platelet aggregation in whole blood showed inverse correlations with the nitrite levels in whole blood and erythrocytes. CONCLUSION: Nitrite alone at physiological levels has no effect on platelets in plasma. Nitrite in the presence of erythrocytes inhibits platelets through its reduction to NO, which is promoted by deoxygenation. Nitrite may have role in modulating platelet activity in the circulation, especially during hypoxia.

  5. Chemically modified field effect transistors with nitrite or fluoride selectivity

    NARCIS (Netherlands)

    Antonisse, Martijn M.G.; Snellink-Ruël, Bianca H.M.; Engbersen, Johan F.J.; Reinhoudt, David N.

    1998-01-01

    Polysiloxanes with different types of polar substituents are excellent membrane materials for nitrite and fluoride selective chemically modified field effect transistors (CHEMFETs). Nitrite selectivity has been introduced by incorporation of a cobalt porphyrin into the membrane; fluoride selectivity

  6. 硫酸钛催化合成丙酸异戊酯%A Study on Esterification of Propanoic Acid and iso-Amyl Alcohol Catalyzed by titanium sulphate

    Institute of Scientific and Technical Information of China (English)

    廖德仲; 何节玉

    2001-01-01

      采用Ti(SO4)2·4H2O作催化剂,探讨了丙酸和异戊醇反应的酯化条件,最佳条件下丙酸的转化率高达96%。%  Ti(SO4)2·4H2O was used as catalyst in the esterification of propanoic acid and iso-amyl alcohol. The conditions of esterification were discussed. In the optimun condition, the yield of iso-amyl propanoate was above 96%.

  7. Biodegradation of ethyl t-butyl ether (ETBE), methyl t-butyl ether (MTBE) and t-amyl methyl ether (TAME) by Gordonia terrae.

    Science.gov (United States)

    Hernandez-Perez, G; Fayolle, F; Vandecasteele, J P

    2001-01-01

    Gordonia terrae strain IFP 2001 was selected from activated sludge for its capacity to grow on ethyl t-butyl ether (ETBE) as sole carbon and energy source. ETBE was stoichiometrically degraded to t-butyl alcohol (TBA) and the activity was inducible. A constitutive strain, G. terrae IFP 2007, derived from strain IFP 2001, was also selected. Methyl t-butyl ether (MTBE) and t-amyl methyl ether (TAME) were not used as carbon and energy sources by the two strains, but cometabolic degradation of MTBE and TAME was demonstrated, to TBA and t-amyl alcohol (TAA) respectively, in the presence of a carbon source such as ethanol. No two-carbon compound was detected during growth on ETBE, but formate was produced during cometabolic degradation of MTBE or TAME. A monooxygenase was involved in the degradation of ethers, because no degradation of ETBE was observed under anaerobic conditions and the presence of a cytochrome P-450 was demonstrated in G. terrae IFP 2001 after induction by cultivation on ETBE.

  8. Generation of nitric oxide from nitrite by carbonic anhydrase:

    DEFF Research Database (Denmark)

    Aamand, Rasmus; Dalsgaard, Thomas; Jensen, Frank Bo;

    2009-01-01

    bicarbonate and nitrite, we hypothesized that CA uses nitrite as a substrate to produce the potent vasodilator nitric oxide (NO) to increase local blood flow to metabolically active tissues. Here we show that CA readily reacts with nitrite to generate NO, particularly at low pH, and that the NO produced...

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

    DEFF Research Database (Denmark)

    Jensen, Frank Bo; Rohde, Sabina

    2010-01-01

    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 (So2), 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 HNO2...... diffusion and AE1-mediated facilitated NO2- diffusion. Participation of HNO2 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...

  10. Nitric oxide formation from nitrite in zebrafish

    DEFF Research Database (Denmark)

    Jensen, Frank Bo

    2007-01-01

    nitrite levels for variable time periods, and changes in blood nitrosylhemoglobin (HbNO), methemoglobin (metHb), oxygenated hemoglobin (oxyHb) and deoxygenated hemoglobin (deoxyHb) were evaluated by spectral deconvolution. Blood HbNO (a biomarker of internal NO production) was low in controls, increased......, and the possibility that excess NO may inhibit mitochondrial respiration, whole animal routine oxygen consumption was not depressed....

  11. Nitrite in feed: From Animal health to human health

    Energy Technology Data Exchange (ETDEWEB)

    Cockburn, Andrew [Institute for Research on Environment and Sustainability, Devonshire Building, University of Newcastle upon Tyne, Newcastle upon Tyne, NE17RU (United Kingdom); Brambilla, Gianfranco [Istituto Superiore di Sanità, Toxicological chemistry unit, Viale Regina Elena 299, 00161 Rome (Italy); Fernández, Maria-Luisa [Departamento de Medio Ambiente, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Ministerio de Ciencia e Innovación, Carretera de la Coruña, 28040 Madrid (Spain); Arcella, Davide [Unit on Data Collection and Exposure, European Food Safety Authority, Largo N. Palli 5/A43100 Parma (Italy); Bordajandi, Luisa R. [Unit on Contaminants in the Food chain, European Food Safety Authority, Largo N. Palli 5/A, 43100 Parma (Italy); Cottrill, Bruce [Policy Delivery Group, Animal Health and Welfare, ADAS, Wolverhampton (United Kingdom); Peteghem, Carlos van [University of Gent, Harelbekestraat 72, 9000 Gent (Belgium); Dorne, Jean-Lou, E-mail: jean-lou.dorne@efsa.europa.eu [Unit on Contaminants in the Food chain, European Food Safety Authority, Largo N. Palli 5/A, 43100 Parma (Italy)

    2013-08-01

    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 of 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

  12. Nitrite isotopes as tracers of marine N cycle processes

    Science.gov (United States)

    Casciotti, Karen L.

    2016-11-01

    Nitrite (NO2-) is a key intermediate in the marine nitrogen (N) cycle. It is produced and consumed throughout the ocean by the dominant processes driving the distribution, availability and speciation of N. However, the accumulation of nitrite is typically confined to depths near the base of the sunlit euphotic zone and in oxygen-deficient zones. These features are known as the primary and secondary nitrite maximum (PNM and SNM), respectively. The processes controlling nitrite accumulation in these features are not fully understood, but are thought to depend on the microbial community composition and its response to environmental conditions. A variety of approaches have been applied to understanding these features since their discovery, with the stable N and oxygen (O) isotope measurements of nitrite being added to this toolkit most recently. Large variations in nitrite N isotope ratios (15N/14N) and dramatic depletions in 15N contrast with more consistent nitrite O isotope ratios (18O/16O) in the SNM. These signals provide unique information about the mechanisms of nitrite consumption in the SNM. By contrast, nitrite in the PNM shows less variation in 15N/14N, but variations in 18O/16O that provide insight into the mechanisms and rates of N cycling there. This review presents a synthesis of nitrite isotope measurements in the marine environment, highlighting the insights that have been gained from these measurements. This article is part of the themed issue 'Biological and climatic impacts of ocean trace element chemistry'.

  13. 水杨酸正戊酯的催化合成研究%Synthesis of n-Amyl Salicylate Catalyzed by Sodium Hydrogen Sulfate

    Institute of Scientific and Technical Information of China (English)

    杨华; 马荣萱

    2009-01-01

    n-Amyl salicylate was synthesized from salicylic acid and n-pentanol using sodium hydrogen sulfate as catalyst. Factors influencing the ether yield,such as molar ratio of alcohol to acid,catalyst dosage,reaction time,water carrier dosage were discussed. Experimental results showed that sodium hydrogen sulfate was an excellent catalyst. The optimum synthetic conditions were as follows: molar ratio of salicylic acid to n-pentanol was 1∶1.5,catalyst dosage was 4.7% of mass of the reactants,using 10 mL of cyclohexane as water carrier,reaction temperature was 120~140℃ and reaction time was 4.5 h.Under above conditions, the yield of n-amyl salicylate achieved 93.3%.%以水杨酸和正戊醇为原料,用一水合硫酸氢钠催化合成水杨酸正戊酯.研究了酸醇摩尔比、催化剂用量、反应时间及带水剂用量等因素对酯收率的影响.结果表明,一水合硫酸氢钠是合成水杨酸正戊酯的良好催化剂.最佳反应条件如下:酸醇摩尔比为1∶1.5,催化剂用量为反应物总质量的4.7%,带水剂环己烷用量为10 mL,反应时间为4.5 h,反应温度为120~140℃.在此条件下,水杨酸正戊酯的收率可达93.3%.

  14. Biodegradation of the gasoline oxygenates methyl tert-butyl ether, ethyl tert-butyl ether, and tert-amyl methyl ether by propane-oxidizing bacteria.

    Science.gov (United States)

    Steffan, R J; McClay, K; Vainberg, S; Condee, C W; Zhang, D

    1997-11-01

    Several propane-oxidizing bacteria were tested for their ability to degrade gasoline oxygenates, including methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), and tert-amyl methyl ether (TAME). Both a laboratory strain and natural isolates were able to degrade each compound after growth on propane. When propane-grown strain ENV425 was incubated with 20 mg of uniformly labeled [14C]MTBE per liter, the strain converted > 60% of the added MTBE to 14CO2 in production of nearly stoichiometric amounts of tert-butyl alcohol (TBA), while the initial oxidation of TAME resulted in the production of tert-amyl alcohol. The methoxy methyl group of MTBE was oxidized to formaldehyde and ultimately to CO2. TBA was further oxidized to 2-methyl-2-hydroxy-1-propanol and then 2-hydroxy isobutyric acid; however, neither of these degradation products was an effective growth substrate for the propane oxidizers. Analysis of cell extracts of ENV425 and experiments with enzyme inhibitors implicated a soluble P-450 enzyme in the oxidation of both MTBE and TBA. MTBE was oxidized to TBA by camphor-grown Pseudomonas putida CAM, which produces the well-characterized P-450cam, but not by Rhodococcus rhodochrous 116, which produces two P-450 enzymes. Rates of MTBE degradation by propane-oxidizing strains ranged from 3.9 to 9.2 nmol/min/mg of cell protein at 28 degrees C, whereas TBA was oxidized at a rate of only 1.8 to 2.4 nmol/min/mg of cell protein at the same temperature.

  15. Biomass Industrial Effluent Effect on Carbohydrates, Aminoacids, Nitrite and Nitrite Enzyme Activities of Arachis hypogaea L

    Institute of Scientific and Technical Information of China (English)

    PC Nagajyoti; N Dinakarc; S Suresh; Y Udaykiran; C Suresh; T N V K V Prasad; T Damodharam

    2009-01-01

    The objectives of the present investigations are to see the effects of biomass power plant effluent on the carbohydrates, aminoacids, nitrite and nitrite enzyme activitiesand proline of Arachis hypogaea L. vat TCGS 320 under controlled pot culture methods. Plants were cultivated with 25, 50, 75 and 100% of the effluent and a control without the effluent. The treatment of the crop with 25% of the effluent has shown stimulatory effect on all the biochemical parameters studied. Carbohydrates, starch, aminoacids, protein, nitrate and nitrite reductase enzymatic activities have increased in 10, 15, 20 DAS (days after sowing). In 25 and 30 DAS all biochemical parameters have decreased, due to environmental factors (rainfall, temperature, humidity, etc.). The present investigation clearly indicated that the biomass power plant effluent has stimulatory effect on all the biochemical contents at lower concentration, and at higher concentration they have deleterious effects.

  16. Unraveling the origin of the nitrite-mediated hypoxic vasodilation

    DEFF Research Database (Denmark)

    Fago, Angela; Dalsgaard, T.; Simonsen, U.

    2007-01-01

    Circulating nitrite has recently emerged as an important physiological metabolite that contributes to increase vasodilation during tissue hypoxia. Using a wire myograph, we have investigated how the nitrite-dependent vasodilation in rat aortic rings is controlled by oxygen tension, norepinephrine...... are sufficient to induce NO-mediated vasodilation independently of the nitrite reductase activities here investigated. These results further indicate that the vasoactive effect of nitrite is intrinsic to the vessel and may be due to S-nitrosothiols formed within the arterial smooth muscle....

  17. The role of nitrite in nitric oxide homeostasis

    DEFF Research Database (Denmark)

    Jensen, Frank Bo

    2009-01-01

    Nitrite is endogenously produced as an oxidative metabolite of nitric oxide, but it also functions as a NO donor that can be activated by a number of cellular proteins under hypoxic conditions. This article discusses the physiological role of nitrite and nitrite-derived NO in blood flow regulation...... mechanisms. Nitrite reduction to NO provides cytoprotection in tissues during ischemia-reperfusion events by inhibiting mitochondrial respiration and limiting reactive oxygen species. It is argued that the study of hypoxia-tolerant lower vertebrates and diving mammals may help evaluate mechanisms and a full...

  18. A novel nitrite biosensor based on conductometric electrode modified with cytochrome c nitrite reductase composite membrane.

    Science.gov (United States)

    Zhang, Zhiqiang; Xia, Siqing; Leonard, Didier; Jaffrezic-Renault, Nicole; Zhang, Jiao; Bessueille, François; Goepfert, Yves; Wang, Xuejiang; Chen, Ling; Zhu, Zhiliang; Zhao, Jianfu; Almeida, M Gabriela; Silveira, Célia M

    2009-02-15

    A conductometric biosensor for nitrite detection was developed using cytochrome c nitrite reductase (ccNiR) extracted from Desulfovibrio desulfuricans ATCC 27774 cells immobilized on a planar interdigitated electrode by cross-linking with saturated glutaraldehyde (GA) vapour in the presence of bovine serum albumin, methyl viologen (MV), Nafion, and glycerol. The configuration parameters for this biosensor, including the enzyme concentration, ccNiR/BSA ratio, MV concentration, and Nafion concentration, were optimized. Various experimental parameters, such as sodium dithionite added, working buffer solution, and temperature, were investigated with regard to their effect on the conductance response of the biosensor to nitrite. Under the optimum conditions at room temperature (about 25 degrees C), the conductometric biosensor showed a fast response to nitrite (about 10s) with a linear range of 0.2-120 microM, a sensitivity of 0.194 microS/microM [NO(2)(-)], and a detection limit of 0.05 microM. The biosensor also showed satisfactory reproducibility (relative standard deviation of 6%, n=5). The apparent Michaelis-Menten constant (K(M,app)) was 338 microM. When stored in potassium phosphate buffer (100mM, pH 7.6) at 4 degrees C, the biosensor showed good stability over 1 month. No obvious interference from other ionic species familiar in natural waters was detected. The application experiments show that the biosensor is suitable for use in real water samples.

  19. 用于生产TAEE的反应精馏和全蒸发的混合过程%Hybrid Process of Reactive Distillation and Pervaporation for the Production of Tert-amyl Ethyl Ether

    Institute of Scientific and Technical Information of China (English)

    Amornchai Arpornwichanop; Ukrit Sahapatsombud; Yaneeporn Patcharavorachot; Suttichai Assabumrungrat

    2008-01-01

    In this study, a reactive distillation column in which chemical reaction and separation occur simultane-ously is applied for the synthesis of tert-amyl ethyl ether (TAEE) from ethanol (EtOH) and tert-amyl alcohol (TAA).Pervaporation, an efficient membrane separation technique, is integrated with the reactive distillation for enhancing the efficiency of TAEE production. A user-defined Fortran subroutine of a pervaporation unit is developed, allowing the design and simulation of the hybrid process of reactive distillation and pervaporation in Aspen Plus simulator.The performance of such a hybrid process is analyzed and the results indicate that the integration of the reactive distillation with the pervaporation increases the conversion of TAA and the purity of TAEE product, compared with the conventional reactive distiUation.

  20. Nitrate and nitrite in biology, nutrition and therapeutics

    NARCIS (Netherlands)

    Lundberg, J.O.; van Faassen, E.E.H.; Gladwin, M.T.; Ahluwalia, A.; Benjamin, N.

    2009-01-01

    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.

  1. Bidirectional catalysis by copper-containing nitrite reductase

    NARCIS (Netherlands)

    Wijma, HJ; Canters, GW; de Vries, S; Verbeet, MP

    2004-01-01

    The copper-containing nitrite reductase from Alcaligenes faecalis S-6 was found to catalyze the oxidation of nitric oxide to nitrite, the reverse of its physiological reaction. Thermodynamic and kinetic constants with the physiological electron donor pseudoazurin were determined for both directions

  2. The Impact of Nitrite on Aerobic Growth of Paracoccus denitrificans PD1222

    OpenAIRE

    Hartop, Katherine

    2014-01-01

    The effect of nitrite stress induced in Paracoccus denitrificans PD1222 was examined using additions of sodium nitrite to an aerobic bacterial culture. Nitrite generates a strong stress response in P. denitrificans, causing growth inhibition. This is dependent on both the concentration of nitrite present and the pH. The pH dependent effect of nitrite growth inhibition is likely a result of nitrite and free nitrous acid (FNA; pKa = 3.16) and subsequent reactive nitrogen oxides, ...

  3. Determination of NO chemical affinities of benzyl nitrite in acetonitrile

    Institute of Scientific and Technical Information of China (English)

    Xin LI; Xiaoqing ZHU; Jinpei CHENG

    2008-01-01

    There is an increasing interest in the study of NO chemical affinities of organic nitrites, for the bio-logical and physiological effects of organic nitrites seem to be due to their ability to release NO. In this paper, NO chemical affinities of ten substituted benzyl nitrites were determined by titration calorimetry combined with a ther-modynamic cycle in acetonitrile solution. The results show that ΔHhet(O-NO)s of benzyl nitrites are substan-tially larger than the corresponding ΔHhomo(O-NO)s, suggesting that these O-nitroso compounds much more easily release NO radicals by the O-NO bond homolytic cleavage. It is believed that the structural and energetic information disclosed in this work should be useful in understanding chemical and biological functions of organic nitrites.

  4. Spectrophotometric determination of nitrite using salbutamol sulfate as a reagent

    Energy Technology Data Exchange (ETDEWEB)

    Agrawal, Y.K.; Bhatt, P.N.

    1988-01-01

    A simple spectrophotometric method for the trace determination of nitrite (NO/sub 2//sup /minus//) is described. Nitrite is reacted with Salbutamol sulfate in acidic medium which gives a yellow color in alkaline medium (less than or equal to pH 7) and can be determined in the presence of several cations and anions. Beer's law is obeyed in the range of 1.8 to 27.6 ppm of nitrite with the molar absorptivity 1.8 /times/ 10/sup 3/ 1 /times/ mole /sup /minus/1/ /times/ cm/sup /minus/1/ at 410 nm. The proposed method can also be utilized for the determination of nitrate (NO/sub 3//sup /minus//) after its reduction to nitrite. The method has been applied for the determination of various samples containing traces of nitrite.

  5. Purification and characterization of assimilatory nitrite reductase from Candida utilis.

    Science.gov (United States)

    Sengupta, S; Shaila, M S; Rao, G R

    1996-07-01

    Nitrate assimilation in many plants, algae, yeasts and bacteria is mediated by two enzymes, nitrate reductase (EC 1.6.6.2) and nitrite reductase (EC 1.7.7.1). They catalyse the stepwise reduction of nitrate to nitrite and nitrite to ammonia respectively. The nitrite reductase from an industrially important yeast, Candida utilis, has been purified to homogeneity. Purified nitrite reductase is a heterodimer and the molecular masses of the two subunits are 58 and 66 kDa. The native enzyme exhibits a molecular mass of 126 kDa as analysed by gel filtration. The identify of the two subunits of nitrite reductase was confirmed by immunoblotting using antibody for Cucurbita pepo leaf nitrite reductase. The presence of two different sized transcripts coding for the two subunits was confirmed by (a) in vitro translation of mRNA from nitrate-induced C. utilis followed by immunoprecipitation of the in vitro translated products with heterologous nitrite reductase antibody and (b) Northern-blot analysis. The 66 kDa subunit is acidic in nature which is probably due to its phosphorylated status. The enzyme is stable over a range of temperatures. Both subunits can catalyse nitrite reduction, and the reconstituted enzyme, at a higher protein concentration, shows an activity similar to that of the purified enzyme. Each of these subunits has been shown to contain a few unique peptides in addition to a large number of common peptides. Reduced Methyl Viologen has been found to be as effective an electron donor as NADPH in the catalytic process, a phenomenon not commonly seen for nitrite reductases from other systems.

  6. EPR spectroscopy of nitrite complexes of methemoglobin.

    Science.gov (United States)

    Schwab, David E; Stamler, Jonathan S; Singel, David J

    2010-07-19

    The chemical interplay of nitrogen oxides (NO's) with hemoglobin (Hb) has attracted considerable recent attention because of its potential significance in the mechanism of NO-related vasoactivity regulated by Hb. An important theme of this interplay-redox coupling in adducts of heme iron and NO's-has sparked renewed interest in fundamental studies of FeNO(x) coordination complexes. In this Article, we report combined UV-vis and comprehensive electron paramagnetic resonance (EPR) spectroscopic studies that address intriguing questions raised in recent studies of the structure and affinity of the nitrite ligand in complexes with Fe(III) in methemoglobin (metHb). EPR spectra of metHb/NO(2)(-) are found to exhibit a characteristic doubling in their sharper spectral features. Comparative EPR measurements at X- and S-band frequencies, and in D(2)O versus H(2)O, argue against the assignment of this splitting as hyperfine structure. Correlated changes in the EPR spectra with pH enable complete assignment of the spectrum as deriving from the overlap of two low-spin species with g values of 3.018, 2.122, 1.45 and 2.870, 2.304, 1.45 (values for samples at 20 K and pH 7.4 in phosphate-buffered saline). These g values are typical of g values found for other heme proteins with N-coordinated ligands in the binding pocket and are thus suggestive of N-nitro versus O-nitrito coordination. The positions and shapes of the spectral lines vary only slightly with temperature until motional averaging ensues at approximately 150 K. The pattern of motional averaging in the variable-temperature EPR spectra and EPR studies of Fe(III)NO(2)(-)/Fe(II)NO hybrids suggest that one of two species is present in both of the alpha and beta subunits, while the other is exclusive to the beta subunit. Our results also reconfirm that the affinity of nitrite for metHb is of millimolar magnitude, thereby making a direct role for nitrite in physiological hypoxic vasodilation difficult to justify.

  7. Selection and identification of bacterial strains with methyl-tert-butyl ether, ethyl-tert-butyl ether, and tert-amyl methyl ether degrading capacities.

    Science.gov (United States)

    Purswani, Jessica; Pozo, Clementina; Rodríguez-Díaz, Marina; González-López, Jesús

    2008-11-01

    Nine bacterial strains isolated from two hydrocarbon-contaminated soils were selected because of their capacity for growth in culture media amended with 200 mg/L of one of the following gasoline oxygenates: Methyl-tert-butyl ether (MTBE), ethyl-tert-butyl ether (ETBE), and tert-amyl methyl ether (TAME). These strains were identified by amplification of their 16S rRNA gene, using fDl and rD1 primers, and were tested for their capacity to grow and biotransform these oxygenates in both mineral and cometabolic media. The isolates were classified as Bacillus simplex, Bacillus drentensis, Arthrobacter sp., Acinetobacter calcoaceticus, Acinetobacter sp., Gordonia amicalis (two strains), Nocardioides sp., and Rhodococcus ruber. Arthrobacter sp. (strain MG) and A. calcoaceticus (strain M10) consumed 100 (cometabolic medium) and 82 mg/L (mineral medium) of oxygenate TAME in 21 d, respectively, under aerobic conditions. Rhodococcus ruber (strain E10) was observed to use MTBE and ETBE as the sole carbon and energy source, whereas G. amicalis (strain T3) used TAME as the sole carbon and energy source for growth. All the bacterial strains transformed oxygenates better in the presence of an alternative carbon source (ethanol) with the exception of A. calcoaceticus (strain M10). The capacity of the selected strains to remove MTBE, ETBE, and TAME looks promising for application in bioremediation technologies.

  8. Control factors of partial nitritation for landfill leachate treatment

    Institute of Scientific and Technical Information of China (English)

    LIANG Zhu; LIU Jun-xin

    2007-01-01

    Anaerobic ammonium oxidation (ANAMMOX) technology has potential technical superiority and economical efficiency for the nitrogen removal from landfill leachate, which contains high-strength ammonium nitrogen (NH4+-N) and refractory organics. To complete the ANAMMOX process, a preceding partial nitritation step to produce the appropriate ratio of nitrite/ammonium is a key stage. The objective of this study was to determine the optimal conditions to acquire constant partial nitritation for landfill leachate treatment, and a bench scale fixed bed bio-film reactor was used in this study to investigate the effects of the running factors on the partial nitritation. The results showed that both the dissolved oxygen (DO) concentration and the ammonium volumetric loading rate (Nv) had effects on the partial nitritation. In the controlling conditions with a temperature of 30±1℃, Nv of 0.2-1.0 kg NH4+-N/(m3·d), and DO concentration of 0.8-2.3 mg/L, the steady partial nitritation was achieved as follows: more than 94% partial nitritation efficiency (nitrite as the main product), 60%-74% NH4+-N removal efficiency, and NO2--N/NH4+-N ratio (concentration ratio) of 1.0-1.4 in the effluent.The impact of temperature was related to Nv at certain DO concentration, and the temperature range of 25-30℃ was suitable for treating high strength ammonium leachate. Ammonium-oxidizing bacteria (AOB) could be acclimated to higher FA (free ammonium) in the range of 122-224 mg/L. According to the denaturing gradient gel electrophoresis analysis result of the bio-film in the reactor, there were 25 kinds of 16S rRNA gene fragments, which indicated that abundant microbial communities existed in the bio-film, although high concentrations of ammonium and FA may inhibit the growth of the nitrite-oxidizing bacteria (NOB) and other microorganisms in the reactor.

  9. Impact of mitochondria on nitrite metabolism in HL-1 cardiomyocytes

    Directory of Open Access Journals (Sweden)

    Peter eDungel

    2013-05-01

    Full Text Available Apart from ATP synthesis mitochondria have many other functions, one being nitrite reductase activity. NO released from nitrite has been shown to protect the heart from ischemia/reperfusion injury in a cGMP-dependent manner. However, the exact impact of mitochondria on the release of NO from nitrite in cardiomyocytes is not completely understood. Besides mitochondria, a number of non-mitochondrial metalloproteins have been suggested to facilitate this process. The aim of this study was to investigate the impact of mitochondria on the bioactivation of nitrite in HL-1 cardiomyocytes.The levels of nitrosyl complexes of hemoglobin (NO-Hb and cGMP levels were measured by electron spin resonance spectroscopy and enzyme immunoassay. In addition the formation of free NO was determined by confocal microscopy as well as intracellular nitrite and S-nitrosothiols by chemoluminescence analysis. NO was released from nitrite in cell culture in an oxygen dependent manner. Application of specific inhibitors of the respiratory chain, p450, NO synthases and xanthine oxidoreductase showed that all four enzymatic systems are involved in the release of NO, but more than 50% of NO is released via the mitochondrial pathway. Only NO released by mitochondria activated cGMP synthesis. Cardiomyocytes co-cultured with red blood cells (RBC competed with RBC for nitrite, but free NO was detected only in HL-1 cells suggesting that RBC are not a source of NO in this model. Apart from activation of cGMP synthesis, NO formed in HL-1 cells diffused out of the cells and formed NO-Hb complexes. In addition nitrite was converted by HL-1 cells to S-nitrosyl complexes. In HL-1 cardiomyocytes, several enzymatic systems are involved in nitrite reduction to NO but only the mitochondrial pathway of NO release activates cGMP synthesis. Our data suggest that this pathway may be a key regulator of myocardial contractility especially under hypoxic conditions.

  10. Modeling the Impact of Ingoing Sodium Nitrite, Sodium Ascorbate, and Residual Nitrite Concentrations on Growth Parameters of Listeria monocytogenes in Cooked, Cured Pork Sausage.

    Science.gov (United States)

    King, Amanda M; Glass, Kathleen A; Milkowski, Andrew L; Seman, Dennis L; Sindelar, Jeffrey J

    2016-02-01

    Sodium nitrite has been identified as a key antimicrobial ingredient to control pathogens in ready-to-eat (RTE) meat and poultry products, including Listeria monocytogenes. This study was designed to more clearly elucidate the relationship between chemical factors (ingoing nitrite, ascorbate, and residual nitrite) and L. monocytogenes growth in RTE meats. Treatments of cooked, cured pork sausage (65% moisture, 1.8% salt, pH 6.6, and water activity 0.98) were based on response surface methodology with ingoing nitrite and ascorbate concentrations as the two main factors. Concentrations of nitrite and ascorbate, including star points, ranged from 0 to 352 and 0 to 643 ppm, respectively. At one of two time points after manufacturing (days 0 and 28), half of each treatment was surface inoculated to target 3 log CFU/g of a five-strain L. monocytogenes cocktail, vacuum packaged, and stored at 7°C for up to 4 weeks. Growth of L. monocytogenes was measured twice per week, and enumerations were used to estimate lag time and growth rates for each treatment. Residual nitrite concentrations were measured on days 0, 4, 7, 14, 21, and 28, and nitrite depletion rate was estimated by using first-order kinetics. The response surface methodology was used to model L. monocytogenes lag time and growth rate based on ingoing nitrite, ascorbate, and the residual nitrite remaining at the point of inoculation. Modeling results showed that lag time was impacted by residual nitrite concentration remaining at inoculation, as well as the squared term of ingoing nitrite, whereas growth rate was affected by ingoing nitrite concentration but not by the remaining residual nitrite at the point of inoculation. Residual nitrite depletion rate was dependent upon ingoing nitrite concentration and was only slightly affected by ascorbate concentration. This study confirmed that ingoing nitrite concentration influences L. monocytogenes growth in RTE products, yet residual nitrite concentration contributes

  11. Generation of nitric oxide from nitrite by carbonic anhydrase

    DEFF Research Database (Denmark)

    Aamand, Rasmus; Dalsgaard, Thomas; Jensen, Frank B;

    2009-01-01

    In catalyzing the reversible hydration of CO2 to bicarbonate and protons, the ubiquitous enzyme carbonic anhydrase (CA) plays a crucial role in CO2 transport, in acid-base balance, and in linking local acidosis to O2 unloading from hemoglobin. Considering the structural similarity between...... in the reaction induces vasodilation in aortic rings. This reaction occurs under normoxic and hypoxic conditions and in various tissues at physiological levels of CA and nitrite. Furthermore, two specific inhibitors of the CO2 hydration, dorzolamide and acetazolamide, increase the CA-catalyzed production...... of vasoactive NO from nitrite. This enhancing effect may explain the known vasodilating effects of these drugs and indicates that CO2 and nitrite bind differently to the enzyme active site. Kinetic analyses show a higher reaction rate at high pH, suggesting that anionic nitrite participates more effectively...

  12. [Spectrophotofluorimetric determination of trace nitrite with safranine T].

    Science.gov (United States)

    Dong, Cun-zhi; Wu, Wei-dong

    2003-02-01

    A new fluorescence quenching method has been developed to determine nitrite in water samples. The method is based on the diazo-reaction between nitrite ion and safranine T in hydrochloric acid medium. The fluorescence intensity was measured at excitation and emission wavelengths of 525.0 and 556.0 nm, respectively. The optimum experimental conditions have been confirmed and the concentration of hydrochloric acid was 0.096 mol.L-1; the reaction time was 10 min. Under the selected conditions, the relationship was obtained between the fluorescence intensity and nitrite concentration in the range 4-200 x 10(-9) g.mL-1 NO2-. The detection limit was 4 x 10(-9) g.mL-1 NO2-. The method was applied to determine trace nitrite in water samples. The mechanism involved in the reaction was discussed.

  13. A Review of Nitrate and Nitrite Toxicity in Foods

    Directory of Open Access Journals (Sweden)

    Mir-Jamal Hosseini

    2016-03-01

    Full Text Available Agricultural advancement and population growth have prompted increases in food supplies, and higher crop yields have been made possible through the application of fertilizers. Large quantities of livestock and poultry on farms, along with the accumulation of biomass and agricultural residues, can cause contamination of ground water resources and other water sanitation concerns in both developing and developed countries. Nitrate is mainly used as a fertilizer in agriculture, and because of its high solubility in water, it can create biological problems in the environment. High usage of nitrite in the food industry as a preservative, flavor enhancer, antioxidant, and color stabilizing agent can cause human exposure to this toxic compound. Nitrite is 10 times as toxic as nitrate in humans. Nitrate is converted to nitrite and nitrosamine compounds in the human stomach, which can lead to bladder cancer. In this review, sources of nitrate and nitrite exposure were investigated. Furthermore, the review evaluates standard levels of nitrate and nitrite in different foods, and acceptable daily doses of these compounds in various countries. Finally, we discuss valid methods of nitrate and nitrite identification and removal in foods.

  14. Liquid/air partition coefficients of methyl and ethyl T-butyl ethers, T-amyl methyl ether, and T-butyl alcohol.

    Science.gov (United States)

    Nihlen, A; Lof, A; Johanson, G

    1995-01-01

    Partition coefficients are essential to a description of the uptake and distribution of volatile substances in humans and in the development of physiologically based pharmacokinetic models. Liquid/air partition coefficients (lambda) of three ethers, methyl t-butyl ether (MTBE), ethyl t-butyl ether (ETBE), and t-amyl methyl ether (TAME) were determined in vitro by head space-gas chromatography. These ethers, and especially MTBE, are used in unleaded gasoline to enhance the oxygen and octane content, and to reduce the output of carbon monoxide during combustion. Partition coefficients of t-butyl alcohol (TBA), a metabolite of MTBE, were determined also. The liquids tested were fresh human blood, water (physiological saline), and olive oil. The (lambda)blood/air values were: 17.7 (95% confidence interval 17.0-18.4) for MTBE; 11.7 (11.3-12.1) for ETBE; and 17.9 (17.3-18.5) for TAME. Corresponding (lambda)water/air values were 15.2 (14.9-15.5), 8.39 (8.19-8.59), and 11.9 (11.7-12.1). The ethers have a higher affinity for oil, the values for (lambda)oil/air being 120 (114-125), 190 (183-197), and 337 (320-354), respectively. As expected, the (lambda)blood/air and (lambda)water/air for TBA were much higher than for the ethers, 462 (440-484) and 603 (590-617), respectively. The (lambda)oil/air was 168 (161-174) for TBA. The interindividual variability of the (lambda)blood/air (10 subjects) was calculated as the coefficient of variation, and estimated as: 14% for MTBE, 20% for ETBE, 20% for TAME, and 30% for TBA. No significant difference was seen in the (lambda)blood/air between the sexes.

  15. Effect of Dry Red Grape Pomace as a Nitrite Substitute on the Microbiological and Physicochemical Properties and Residual Nitrite of Dry-cured Sausage

    Directory of Open Access Journals (Sweden)

    Fatemeh Riazi

    2016-07-01

    Full Text Available Background and Objectives: Sodium nitrite and potassium nitrite have been traditionally used for inhibition of Clostridium botulinum and also as an agent to stabilize the color of meat products; however, usage of these additives at high levels could lead to toxicity and cancer originating from the formation of nitrosamines. Nowadays, application of natural preservatives in order to reduce the nitrite content in meat products is increasing. Thus, we used dry red grape pomace (DRGP as a natural alternative to sodium nitrite. Materials and Methods: The effect of two levels of DRGP (1 and 2% on the proximate composition, microbial counts, pH values and residual nitrite level of the samples formulated with two levels of sodium nitrite (30 and 60 mg/kg, as well as the comparison of these sausages with the blank (nitrite-free  and control (full nitrite added samples on the 1rst, 10th, 20th and 30th days of storage at 3-5 °C were evaluated. Results: The results showed that all chemical compositions were in the ranges reported by other researchers, and nitrite was very effective in preventing the microbial growth. Also about 50 % of the ingoing nitrite could be analyzed in the samples after processing. Moreover, the residual nitrite level declined both during the storage of sausage and after the addition of DRGP. Conclusions: The use of DRGP in combination with nitrite for sausages was more effective in keeping the quality and safety of the refrigerated consumer products as indicated by the lower nitrite levels, microbial count and similar composition as compared to the samples treated with nitrite and without nitrite. Keywords: Dry red grape pomace (DRGP, Sausage, Nitrite, Microbial count

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

    Science.gov (United States)

    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.

  17. Nitrite reduction mechanism on a Pd surface.

    Science.gov (United States)

    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).

  18. Magnetic resonance study of the transmembrane nitrite diffusion.

    Science.gov (United States)

    Samouilov, A; Woldman, Ya Yu; Zweier, J L; Khramtsov, V V

    2007-05-01

    Nitrite (NO(2)-), being a product of metabolism of both nitric oxide (NO(*)) and nitrate (NO(3)-), can accumulate in tissues and regenerate NO() by several mechanisms. The effect of NO(2)- on ischemia/reperfusion injury was also reported. Nevertheless, the mechanisms of intracellular NO(2)- accumulation are poorly understood. We suggested significant role of nitrite penetration through biological membranes in the form of undissociated nitrous acid (HNO(2)). This hypothesis has been tested using large unilamellar phosphatidylcholine liposomes and several spectroscopic techniques. HNO(2) transport across the phospholipid bilayer of liposomes facilitates proton transfer resulting in intraliposomal acidification, which was measured using pH-sensitive probes. NO(2)(-)-mediated intraliposomal acidification was confirmed by EPR spectroscopy using membrane-impermeable pH-sensitive nitroxide, AMC (2,2,5,5-tetramethyl-1-yloxy-2,5-dihydro-1H-imidazol-3-ium-4-yl)-aminomethanesulfonic acid (pK 5.25), and by (31)P NMR spectroscopy using inorganic phosphate (pK 6.9). Nitrite accumulates inside liposomes in concentration exceeding its concentration in the bulk solution, when initial transmembrane pH gradient (alkaline inside) is applied. Intraliposomal accumulation of NO(2)- was observed by direct measurement using chemiluminescence technique. Perfusion of isolated rat hearts with buffer containing 4 microM NO(2)- was performed. The nitrite concentrations in the effluent and in the tissue, measured after 1 min perfusion, were close, supporting fast penetration of the nitrite through the tissue. Measurements of the nitrite/nitrate showed that total concentration of NO(x) in myocardium increased from initial 7.8 to 24.7 microM after nitrite perfusion. Physiological significance of passive transmembrane transport of NO(2)- and its coupling with intraliposomal acidification are discussed.

  19. Increased Salivary Nitrite and Nitrate Excretion in Rats with Cirrhosis.

    Science.gov (United States)

    Mahmoodi, Somayeh; Rahmatollahi, Mahdieh; Shahsavari, Fatemeh; Shafaroodi, Hamed; Grayesh-Nejad, Siyavash; Dehpour, Ahmad R

    2015-11-01

    Increased nitric oxide (NO) formation is mechanistically linked to pathophysiology of the extrahepatic complications of cirrhosis. NO is formed by either enzymatic or non-enzymatic pathways. Enzymatic production is catalyzed by NO synthase (NOS) while entero-salivary circulation of nitrate and nitrite is linked to non-enzymatic formation of NO under acidic pH in the stomach. There is no data on salivary excretion of nitrate and nitrite in cirrhosis. This study was aimed to investigate salivary levels of nitrate and nitrite in a rat model of biliary cirrhosis. Cirrhosis was induced by bile duct ligation (BDL). Four weeks after the operation, submandibular ducts of anesthetized BDL and control rats were cannulated with polyethylene microtube for saliva collection. Assessment of pH, nitrite and nitrate levels was performed in our research. We also investigated NOS expression by real time RT-PCR to estimate eNOS, nNOS and iNOS mRNA levels in the submandibular glands. Salivary pH was significantly lower in BDL rats in comparison to control animals. We also observed a statistically significant increase in salivary levels of nitrite as well as nitrate in BDL rats while there was no elevation in the mRNA expression of nNOS, eNOS, and iNOS in submandibular glands of cirrhotic groups. This indicates that an increased salivary level of nitrite/nitrate is less likely to be linked to increased enzymatic production of NO in the salivary epithelium. It appears that nitrate/nitrite can be transported from the blood stream by submandibular glands and excreted into saliva as entero-salivary circulation, and this mechanism may have been exaggerated during cirrhosis.

  20. Sodium nitrite: the "cure" for nitric oxide insufficiency.

    Science.gov (United States)

    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.

  1. 过氧化叔戊醇对苯并噻吩类衍生物的氧化%Oxidation of benzothiophenes using tert-amyl hydroperoxide

    Institute of Scientific and Technical Information of China (English)

    周新锐; 盖洪涛; 王静; 张珊珊; 杨锦宗; 张淑芬

    2009-01-01

    Homogeneous oxidation using an oil-soluble oxidant,tert-amyl hydroperoxide(TAHP).for ultra-deep desulfurizmion was performed under mild conditions in the presence of molybdenum oxide catalysts.Dibenzothio phene(DBT),benzothiophcne(BT)and 4,6-dimethyl-dibenzothiophene(DMDBT),which are the refractory sulfur compounds for hydrodesulfurization(HDS),were employed as model substrates for a simulated diesel fuel.Activ ity of molybdenum oxide supported on a macroporous weak acidic resin was investigated.The mass conversion of DBT reached near 100%at 90°C and a TAHP,DBT molar ratio of 3 with 1% of molybdenum oxide supported on Amberlite IRC-748 resin for l h.It was further found that the activities of the model Substrates decreasca rin the order of DMDBT>DBT>B T.In the flow oxidation using TAHP as the oxidant,mass conversion of DBT increased remarkably from 61.3%to 98.5%when dropping the weight hourly space velocity(WHSV)from 40 h1 to 10 h-1.A series of experiments dealt with selectivity of this oxidation using TAHP revealed that the model unsaturated compounds,i.e.4,6,8-trimethyl-2-nonylene,and 2-methylnaphthaIene did not affect the oxidation of DBT.Carbazole had nearly no effect on the conversion of DBT using TAHP.but had some influence on the one using tert-butyl hydroperoxide(TBHP).The mass conversion of DBT decreased remarkably from 75.2%to 3.6%when the content of carbazole increased from 0 to 500 ug.g-1.In the flow oxidation using TAHP as the oxidant.the concentration of.DBT in model fuels was reduced from 500 ug.g-1 to 7.2 ug.g-1 at WHSV of 10 h-1,and then reduced to 3.8 ug.g-1 by adsorption of Al2O3.

  2. Immobilization of nitrite oxidizing bacteria using biopolymeric chitosan media

    Institute of Scientific and Technical Information of China (English)

    Pranee Lertsutthiwong; Duangcheewan Boonpuak; Wiboonluk Pungrasmi; Sorawit Powtongsook

    2013-01-01

    The effects of chitosan characteristics including the degree of deacetylation,molecular weight,particle size,pH pretreatment and immobilization time on the immobilization of nitrite-oxidizing bacteria (NOB) on biopolymeric chitosan were investigated.Nitrite removal efficiency of immobilized NOB depended on the degree of deacetylation,particle size,pH pretreatment on the surface of chitosan and immobilization time.Scanning electron microscope characterization illustrated that the number of NOB cells attached to the surface of chitosan increased with an increment of immobilization time.The optimal condition for NOB immobilization on chitosan was achieved during a 24-hr immobilization period using chitosan with the degree of deacetylation larger than 80% and various particle size ranges between 1-5 mm at pH 6.5.In general,the NOB immobilized on chitosan flakes has a high potential to remove excess nitrite from wastewater and aquaculture systems.

  3. Hydrogen sulfide poisoning: an antidotal role for sodium nitrite?

    Science.gov (United States)

    Hall, A H; Rumack, B H

    1997-06-01

    In 2 separate incidents, 6 patients were poisoned with hydrogen sulfide (H2S) in sewer gas. In the first incident, mixing acid- and sodium hydroxide-based drain cleaners in a confined space resulted in 4 poisonings and 2 deaths. Three would-be rescuers were seriously poisoned and 1 died. Two survivors had neurological sequelae. Sodium nitrite appeared to have some clinical efficacy in 1 case. The second incident involved 2 patients working on a pump in a sewage pond. A patient lying on a raft close to the pond surface was seriously poisoned; sodium nitrite was clinically efficacious and this patient survived without developing neurological sequelae. Sodium nitrite deserves further clinical study as a potential H2S antidote.

  4. Dietary nitrite improves insulin signaling through GLUT4 translocation.

    Science.gov (United States)

    Jiang, Hong; Torregrossa, Ashley C; Potts, Amy; Pierini, Dan; Aranke, Mayank; Garg, Harsha K; Bryan, Nathan S

    2014-02-01

    Diabetes mellitus type 2 is a syndrome of disordered metabolism with inappropriate hyperglycemia owing to a reduction in the biological effectiveness of insulin. Type 2 diabetes is associated with an impaired nitric oxide (NO) pathway that probably serves as the key link between metabolic disorders and cardiovascular disease. Insulin-mediated translocation of GLUT4 involves the PI3K/Akt kinase signal cascade that results in activation of endothelial NO synthase (eNOS). eNOS is dysfunctional during diabetes. We hypothesize that loss of eNOS-derived NO terminates the signaling cascade and therefore cannot activate GLUT4 translocation and that dietary nitrite may repair this pathway. In this study, we administered 50mg/L sodium nitrite to db/db diabetic mice for 4 weeks. After 4 weeks treatment, the db/db mice experienced less weight gain, improved fasting glucose levels, and reduced insulin levels. Cell culture experiments using CHO-HIRc-myc-GLUT4eGFP cell lines stably expressing insulin receptor and myc-GLUT4eGFP protein, as well as L6 skeletal muscle cells stably expressing rat GLUT4 with a Myc epitope (L6-GLUT4myc), showed that NO, nitrite, and GSNO stimulate GLUT4 translocation independent of insulin, which is inhibited by NEM. Collectively our data suggest that nitrite improves insulin signaling through restoration of NO-dependent nitrosation of GLUT4 signaling translocation. These data suggest that NO-mediated nitrosation of GLUT4 by nitrite or other nitrosating agents is necessary and sufficient for GLUT4 translocation in target tissue. Description of this pathway may justify a high-nitrate/nitrite diet along with the glycemic index to provide a safe and nutritional regimen for the management and treatment of diabetes.

  5. Nebulization of the acidified sodium nitrite formulation attenuates acute hypoxic pulmonary vasoconstriction

    Directory of Open Access Journals (Sweden)

    Surber Mark W

    2010-06-01

    Full Text Available Abstract Background Generalized hypoxic pulmonary vasoconstriction (HPV occurring during exposure to hypoxia is a detrimental process resulting in an increase in lung vascular resistance. Nebulization of sodium nitrite has been shown to inhibit HPV. The aim of this project was to investigate and compare the effects of nebulization of nitrite and different formulations of acidified sodium nitrite on acute HPV. Methods Ex vivo isolated rabbit lungs perfused with erythrocytes in Krebs-Henseleit buffer (adjusted to 10% hematocrit and in vivo anesthetized catheterized rabbits were challenged with periods of hypoxic ventilation alternating with periods of normoxic ventilation. After baseline hypoxic challenges, vehicle, sodium nitrite or acidified sodium nitrite was delivered via nebulization. In the ex vivo model, pulmonary arterial pressure and nitric oxide concentrations in exhaled gas were monitored. Nitrite and nitrite/nitrate were measured in samples of perfusion buffer. Pulmonary arterial pressure, systemic arterial pressure, cardiac output and blood gases were monitored in the in vivo model. Results In the ex vivo model, nitrite nebulization attenuated HPV and increased nitric oxide concentrations in exhaled gas and nitrite concentrations in the perfusate. The acidified forms of sodium nitrite induced higher levels of nitric oxide in exhaled gas and had longer vasodilating effects compared to nitrite alone. All nitrite formulations increased concentrations of circulating nitrite to the same degree. In the in vivo model, inhaled nitrite inhibited HPV, while pulmonary arterial pressure, cardiac output and blood gases were not affected. All nitrite formulations had similar potency to inhibit HPV. The tested concentration of appeared tolerable. Conclusion Nitrite alone and in acidified forms effectively and similarly attenuates HPV. However, acidified nitrite formulations induce a more pronounced increase in nitric oxide exhalation.

  6. Physiology and interaction of nitrate and nitrite reduction in Staphylococcus carnosus.

    Science.gov (United States)

    Neubauer, H; Götz, F

    1996-04-01

    Staphylococcus carnosus reduces nitrate to ammonia in two steps. (i) Nitrate was taken up and reduced to nitrite, and nitrite was subsequently excreted. (ii) After depletion of nitrate, the accumulated nitrite was imported and reduced to ammonia, which again accumulated in the medium. The localization, energy gain, and induction of the nitrate and nitrite reductases in S. carnosus were characterized. Nitrate reductase seems to be a membrane-bound enzyme involved in respiratory energy conservation, whereas nitrite reductase seems to be a cytosolic enzyme involved in NADH reoxidation. Syntheses of both enzymes are inhibited by oxygen and induced to greater or lesser degrees by nitrate or nitrite, respectively. In whole cells, nitrite reduction is inhibited by nitrate and also by high concentrations of nitrite (> or = 10 mM). Nitrite did not influence nitrate reduction. Two possible mechanisms for the inhibition of nitrite reduction by nitrate that are not mutually exclusive are discussed. (i) Competition for NADH nitrate reductase is expected to oxidize the bulk of the NADH because of its higher specific activity. (ii) The high rate of nitrate reduction could lead to an internal accumulation of nitrite, possibly the result of a less efficient nitrite reduction or export. So far, we have no evidence for the presence of other dissimilatory or assimilatory nitrate or nitrite reductases in S. carnosus.

  7. [Protonation of nitrite is an obligatory stage in the generation of nitric oxide from nitrite in biological systems].

    Science.gov (United States)

    Mikoian, V D; Kubrina, L N; Khachatrian, G N; Vanin, A F

    2006-01-01

    The yield of nitric oxide from 1 mM sodium nitrite differs 200 times when the process was initiated by 10 mM sodium dithionite in the solution of 5 or 150 mM HEPES-buffer (pH 7.4). Dithionite acted both as a strong reductant and an agent that induced a local acidification of solutions without notable change in pH value. The amount of nitric oxide was estimated by the EPR method by measuring the incorporation of nitric oxide to water-soluble complexes of Fe with N-methyl-D-glucamine dithiocarbamate (MGD), which led to the formation of EPR-detectable mononitrosyl iron complexes with MGD (MNIC-MGD). Ten seconds after dithionite addition, the concentration of MNIC - MGD complexes reached 2 microM in 5 mM HEPES-buffer in contrast to 0.01 microM in 150 mM HEPES-buffer. The difference was suggested to be due to a higher life-time of zones with decreased pH values in a weaker weak buffer solution. The life-time was high enough to ensure the protonation of a part of nitrite. The resulting nitrous acid was decomposed to form nitric oxide. The difference in the formation of nitric oxide from nitrite was also observed in weak and strong buffer solutions in the presence of hemoglobin (0.3 mM) or serum albumin (0.5 mM). However, the ratios of nitric oxide yields in weak and strong buffer did not exceed 3-4 times. The increase in the formation of nitric oxide from nitrite was characteristic for the solutions containing both proteins. Large amounts of nitric oxide formed from nitrite was observed in mouse liver preparation subjected to freezing-thawing procedure followed by incubation in 150 mM HEPES-buffer (pH 7.4) and addition of dithionite. The proposition was made that the presence of zones with low pH value in cells and tissues can ensure the predominant operation of the acid mechanism formation of nitric oxide from nitrite. The contribution of the formation of nitric oxide from nitrite catalyzing with heme-containing proteins nitrite reductases can be minor one under these

  8. Effect of the kinetics of ammonium and nitrite oxidation on nitritation success or failure for different biofilm reactor geometries

    DEFF Research Database (Denmark)

    Lackner, Susanne; Smets, Barth F.

    2012-01-01

    The effect of biokinetics on nitritation was investigated in two biofilm geometries, the Membrane Aerated Biofilm Reactor (MABR) and a conventional biofilm system. A 1D biofilm model was used and evaluated by global sensitivity analysis using the variance based Sobol method. The main focus...... strongly depends on the chosen kinetic parameters of AOB and NOB. The maximum specific growth rates (μmax,AOB and μmax,NOB) had the strongest impact on nitritation efficiency (NE). In comparison, the counter-diffusion geometry yielded more parameter combinations (27.5%) that resulted in high NE than the co...

  9. Physiology and interaction of nitrate and nitrite reduction in Staphylococcus carnosus.

    OpenAIRE

    Neubauer, H.; Götz, F

    1996-01-01

    Staphylococcus carnosus reduces nitrate to ammonia in two steps. (i) Nitrate was taken up and reduced to nitrite, and nitrite was subsequently excreted. (ii) After depletion of nitrate, the accumulated nitrite was imported and reduced to ammonia, which again accumulated in the medium. The localization, energy gain, and induction of the nitrate and nitrite reductases in S. carnosus were characterized. Nitrate reductase seems to be a membrane-bound enzyme involved in respiratory energy conserva...

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

    OpenAIRE

    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 ...

  11. Theoretical study on reaction mechanisms of nitrite reduction by copper nitrite complexes: toward understanding and controlling possible mechanisms of copper nitrite reductase.

    Science.gov (United States)

    Maekawa, Shintaro; Matsui, Toru; Hirao, Kimihiko; Shigeta, Yasuteru

    2015-04-30

    Using density functional theory, we studied denitrification reaction mechanisms of copper adducts of tris(pyrazolyl)methane and hydrotris(pyrazolyl)borate models of a copper nitrite reductase (Cu-NiR), and herein propose several possible reaction pathways, including some parts that have never been examined previously. Because electron and proton transfer reactions participate in the enzymatic cycles of Cu-NiR, the Gibbs energy of a proton in solution, G(H(+)), and the redox potential, Eredox, of the model Cu-NiR are also evaluated. Although the pathway where a nitrite is provided as HNO2 is energetically preferable, a well-known reaction pathway passing through the resting state with an active site occupied by a water molecule where nitrite is provided as NO2(-) is the main recognized pathway under normal conditions. These features do not change whether the electron transfer occurs before production of NO or not. However, our results suggest that the pathway involving HNO2 might become dominant under low pH conditions in conjunction with experimental results.

  12. Serum nitrite levels in Sri Lankan patients with leptospirosis

    Institute of Scientific and Technical Information of China (English)

    Rohini I Gunaratna; Shiroma M Handunnetti; MRC Bulathsinghalage; Pranitha Somaratne; Ananda Jayanaga; HJ de Silva; Senaka Rajapakse

    2012-01-01

    Objective:To determine whether blood nitrite levels are elevated in patients with leptospirosis. Methods: Male patients fulfilling clinical and epidemiological criteria for a diagnosis of leptospirosis were recruited. Those with MAT titre of≥400 together with those seroconverting to a titer of≥200 were included in the analysis. Serum nitrite levels were measured in these patients and age, sex matched healthy controls. Results:Patients from 3 hospitals (n=75) were screened during a 3 month period from 28th June to 3rd September 2009, of whom 20 were eligible for the study. Serum nitrite levels were found to be significantly higher in patients with acute leptospirosis [n=20, (0.359±0.229)μM] compared to controls [(n=13,(0.216±0.051)μM] (P=0.014). A significant correlation was also observed between the MAT titre and the day of illness (r = 0.547; P<0.0001). Conclusions: Serum nitrite levels are higher in patients with acute leptospirosis compared to age and sex matched controls. No correlation could be assessed with severity of illness, as sample size was inadequate to determine this.

  13. Evaluation of nitrate and nitrite destruction/separation technologies

    Energy Technology Data Exchange (ETDEWEB)

    Hobbs, D.T.

    1997-08-29

    This report describes and evaluates four types of nitrate and nitrite destruction and separation technologies that could be used to treat the aqueous, alkaline, nitrate-bearing mixed waste that is generated by the In-Tank Precipitation (ITP) process at the Savannah River Site (SRS). The technologies considered in this report include thermal, hydrothermal, chemical, and electrochemical technologies.

  14. The intramolecular electron transfer between copper sites of nitrite reductase

    DEFF Research Database (Denmark)

    Farver, O; Eady, R R; Abraham, Z H

    1998-01-01

    The intramolecular electron transfer (ET) between the type 1 Cu(I) and the type 2 Cu(II) sites of Alcaligenes xylosoxidans dissimilatory nitrite reductase (AxNiR) has been studied in order to compare it with the analogous process taking place in ascorbate oxidase (AO). This internal process...

  15. The redox interplay between nitrite and nitric oxide: From the gut to the brain

    Directory of Open Access Journals (Sweden)

    Cassilda Pereira

    2013-01-01

    We here discuss the implications of the redox conversion of nitrite to ·NO in the gut, how nitrite-derived ·NO may signal from the digestive to the central nervous system, influencing brain function, as well as a putative ascorbate-driven nitrite/NO pathway occurring in the brain.

  16. 21 CFR 172.177 - Sodium nitrite used in processing smoked chub.

    Science.gov (United States)

    2010-04-01

    ... FOOD FOR HUMAN CONSUMPTION Food Preservatives § 172.177 Sodium nitrite used in processing smoked chub. 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....

  17. Neurotoxicity induced by alkyl nitrites: Impairment in learning/memory and motor coordination.

    Science.gov (United States)

    Cha, Hye Jin; Kim, Yun Ji; Jeon, Seo Young; Kim, Young-Hoon; Shin, Jisoon; Yun, Jaesuk; Han, Kyoungmoon; Park, Hye-Kyung; Kim, Hyung Soo

    2016-04-21

    Although alkyl nitrites are used as recreational drugs, there is only little research data regarding their effects on the central nervous system including their neurotoxicity. This study investigated the neurotoxicity of three representative alkyl nitrites (isobutyl nitrite, isoamyl nitrite, and butyl nitrite), and whether it affected learning/memory function and motor coordination in rodents. Morris water maze test was performed in mice after administrating the mice with varying doses of the substances in two different injection schedules of memory acquisition and memory retention. A rota-rod test was then performed in rats. All tested alkyl nitrites lowered the rodents' capacity for learning and memory, as assessed by both the acquisition and retention tests. The results of the rota-rod test showed that isobutyl nitrite in particular impaired motor coordination in chronically treated rats. The mice chronically injected with isoamyl nitrite also showed impaired function, while butyl nitrite had no significant effect. The results of the water maze test suggest that alkyl nitrites may impair learning and memory. Additionally, isoamyl nitrite affected the rodents' motor coordination ability. Collectively, our findings suggest that alkyl nitrites may induce neurotoxicity, especially on the aspect of learning and memory function.

  18. Nitrogen removal via nitrite from municipal landfill leachate

    Institute of Scientific and Technical Information of China (English)

    WU Lina; PENG Chengyao; ZHANG Shujun; PENG Yongzhen

    2009-01-01

    A system consisting of a two-stage up-flow anaerobic sludge blanket (UASB),an anoxic/aerobic (A/O) reactor and a sequencing batch reactor (SBR),was used to treat landfill leachate.During operation,denitrification and methanogenesis took place simultaneously in the first stage UASB (UASB1),and the effluent chemical oxygen demand (COD) was further removed in the second stage UASB (UASB2).Then the denitrification of nitrite and nitrate in the returned sludge by using the residual COD was accomplished in the A/O reactor,and ammonia was removed via nitrite in it.Last but not least,the residual ammonia was removed in SBR as well as nitrite and nitrate which were produced by nitrification.A system consisting of a two-stage UASB and an A/O reactor was used to achieve the stable short-cut nitrification in the first stage (60 d).The effluent of stage one was treated by SBR in the second stage (60 d).The results over 120 d were as follows: when the total nitrogen (TN) concentration of influent leachate was about 2500 mg/L and the ammonia nitrogen concentration was about 2000 mg/L,the short-cut nitrification with 85%-90% nitrite accumulation was achieved stably in the A/O reactor.The TN and ammonia nitrogen removal efficiencies of the system were 98% and 97%,respectively.The residual ammonia,nitrite and nitrate which were produced by nitrification in the A/O reactor could be washed out almost completely in SBR.The TN and ammonia nitrogen concentrations of final effluent were about 39 mg/L and 12 mg/L,respectively.

  19. Effects of seawater salinity on nitrite accumulation in short-range nitrification to nitrite as end product

    Institute of Scientific and Technical Information of China (English)

    YU De-shuang; PENG Yong-zhen; ZHANG Kui

    2004-01-01

    The effect of seawater salinity on nitrite accumulation in short-range nitrification to nitrite as the end productwas studied by using a SBR. Experimental results indicated that the growth of nitrobacteria was inhibited and veryhigh levels of nitrite accumulation at different salinities were achieved under the conditions of 25-28 ℃, pH 7.5-8.0, and the influent ammonia nitrogen of 40-70 mg/L when seawater flow used to flush toilet was less than 35%(salinity 12393 mg/L, Cl- 6778 mg/L) of total domestic wastewater flow, which is mainly ascribed to much highchlorine concentration of seawater. Results showed that high seawater salinity is available for short-range nitrificationto nitrite as the end product. When the seawater flow used to flush toilet accounting for above 70% of the totaldomestic wastewater flow, the removal efficiency of ammonia was still above 80% despite the removal of organicsdeclined obviously(less than 60% ). It was found that the effect of seawater salinity on the removal of organics wasnegative rather than positive one as shown for ammonia removal.

  20. Model-based evaluation on the conversion ratio of ammonium to nitrite in a nitritation process for ammonium-rich wastewater treatment

    Institute of Scientific and Technical Information of China (English)

    LI Xiao-ming; YANG Qi; ZENG Guang-ming; A. Cornelius; K. H. Rosenwinkel; S. Kunst; D. Weichgrebe

    2004-01-01

    Modeling for nitritation process was discussed and analyzed quantlitatively for the factors that influence nitrite accumulation. The results indicated that pH, inorganic carbon source and Hydraulic Retention Time(HRT) as well as biomass concentration are the main factors that influenced the conversion ratio of ammonium to nitrite. A constant high pH can lead to a high nitritation rate and results in high conversion ratio on condition that free ammonia inhibition do not happen. In a CSTR system, without pH control, this conversion ratio can be monitored by pH variation in the reactor. The pH goes down far from the inlet level means a strongly nitrite accumulation. High concentration of alkalinity can promoted the conversion ratio by means of accelerating the nitritation rate through providing sufficient inorganic carbon source(carbon dioxide). When inorganic carbon source was depleted, the nitritation process stopped. HRT adjustment could be an efficient way to make the nitritation system run more flexible, which to some extent can meet the requirements of the fluctuant of inlet parameters such as ammonium concentration, pH, and temperature and so on. Biomass concentration is the key point, especially for a CSTR system in steady state, which was normally circumscribed by the characteristics of bacteria and may also affected by aeration mode and can be increased by prolonging the HRT on the condition of no nitrate accumulation when no recirculation available. The higher the biomass concentration is, the better the nitrite accumulation can be obtained.

  1. Renal carbonic anhydrases are involved in the reabsorption of endogenous nitrite.

    Science.gov (United States)

    Chobanyan-Jürgens, Kristine; Schwarz, Alexandra; Böhmer, Anke; Beckmann, Bibiana; Gutzki, Frank-Mathias; Michaelsen, Jan T; Stichtenoth, Dirk O; Tsikas, Dimitrios

    2012-02-15

    Nitrite (ONO(-)) exerts nitric oxide (NO)-related biological actions and its concentration in the circulation may be of particular importance. Nitrite is excreted in the urine. Hence, the kidney may play an important role in nitrite/NO homeostasis in the vasculature. We investigated a possible involvement of renal carbonic anhydrases (CAs) in endogenous nitrite reabsorption in the proximal tubule. The potent CA inhibitor acetazolamide was administered orally to six healthy volunteers (5 mg/kg) and nitrite was measured in spot urine samples before and after administration. Acetazolamide increased abruptly nitrite excretion in the urine, strongly suggesting that renal CAs are involved in nitrite reabsorption in healthy humans. Additional in vitro experiments support our hypothesis that nitrite reacts with CO(2), analogous to the reaction of peroxynitrite (ONOO(-)) with CO(2), to form acid-labile nitrito carbonate [ONOC(O)O(-)]. We assume that this reaction is catalyzed by CAs and that nitrito carbonate represents the nitrite form that is actively transported into the kidney. The significance of nitrite reabsorption in the kidney and the underlying mechanisms, notably a direct involvement of CAs in the reaction between nitrite and CO(2), remain to be elucidated.

  2. Experimental study of nitrite accumulation in predenitrification biological nitrogen removal process

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The effect of dissolved oxygen (DO) concentration on nitrite accumulation was investigated in a pilot-scale pre-denitrification process at room temperature for 100 days.In the first 10 days,due to the instability of the system,the DO concentration fluctuated between 1.0 and 2.0 mg/L.In the next 14 days,the DO concentration was kept at 0.5 mg/L and nitrite accumulation occurred,with the average nitrite accumulation rate at 91%.From the 25th day,the DO concentration was increased to 2.0 mg/L to destroy the nitrite accumulation,but nitrite accumulation rate was still as high as 90%.From the 38th day the nitrite accumulation rate decreased to 15%-30% linearly.From the 50th day,DO concentration was decreased to 0.5 mg/L to resume nitrite accumulation.Until the 83rd day the nitrite accumulation rate began to increase to 80%.Dissolved oxygen was the main cause of nitrite accumulation,taking into account other factors such as pH,free ammonia concentration,temperature,and sludge retention time.Because of the different affinity for oxygen between nitrite oxidizing bacteria and ammonia oxidizing bacteria when DO concentration was kept at 0.5 rag/L,nitrite accumulation occurred.

  3. PENELITIAN TOKSISITAS AKUT NATRIUM NITRIT PADA HEWAN UJI TIKUS

    Directory of Open Access Journals (Sweden)

    Sri Endreswari

    2012-10-01

    Full Text Available The acute toxicity study of sodium nitrite in the period of observation for 14 days has been carried out on adult male and female rats. The substance was administered orally iu the form of solution in distilled water. Each animal was observed carefully for six hours after administration, continued twice daily for 1.4 days, those including general appearance, body weight changes, signs of toxicity mortality and gross pathology finding. The signs of toxicity were tremor, ataxia and convulsion; mortalities were occurred in about two hours after administration. Some animal recovered after two - four hours. The LD50 in male mice was 121 (86,6-169,4 mg/kg b.w., in female was 116 (86-155.4 mg/kg b.w. Based on the LD50 value, sodium nitrite is classified as moderately toxic substances.

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

    KAUST Repository

    Balk, Melike

    2015-03-02

    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.

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

    Science.gov (United States)

    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.

  6. Simple methods to decrease sodium and nitrite contents in hams

    Directory of Open Access Journals (Sweden)

    Talia Franco-Avila

    2015-07-01

    Full Text Available Introduction: Ham is a product highly consumed by society; however it contains some elements that make it a non-recommended food. Thus, it has been attempted to eliminate or reduce those components.Material and Methods: Content of sodium, nitrites, peroxides and total coliforms were compared after processes of Washing (W and Simple Cooking (SC in turkey and pork ham in a cross-sectional analytical experimental study. Furthermore, sensory acceptance of thesamples through an acceptance test of five points was evaluated. One-way ANOVA with post hoc Bonferroni were used to assess the mean difference between groups. The value of p≤0.05 was considered statistically significant.Results: Both processes reduced the amount of sodium in both types of ham in statistically significant way (p≤0.001. The major percentage of reduction was presented with SC: 73.4% for turkey ham and 63.5% for pork ham. Likewise, the higher percentage of nitrite reduction was 50.6% in pork ham with SC technique (p≤0.05. Peroxide index decreased with both techniques in both hams without statistical significance. Total coliforms count was kept constant in all samples. Higher sensory acceptance of W concerning SC in all sensory characteristics was observed.Conclusions: W and SC techniques reduce sodium, nitrite and peroxide index without affecting the sanitation of hams. Furthermore, W is accepted in all sensory categories. We recommend using W technique before consumption of the product.

  7. The metabolic impact of extracellular nitrite on aerobic metabolism of Paracoccus denitrificans.

    Science.gov (United States)

    Hartop, K R; Sullivan, M J; Giannopoulos, G; Gates, A J; Bond, P L; Yuan, Z; Clarke, T A; Rowley, G; Richardson, D J

    2017-02-07

    Nitrite, in equilibrium with free nitrous acid (FNA), can inhibit both aerobic and anaerobic growth of microbial communities through bactericidal activities that have considerable potential for control of microbial growth in a range of water systems. There has been much focus on the effect of nitrite/FNA on anaerobic metabolism and so, to enhance understanding of the metabolic impact of nitrite/FNA on aerobic metabolism, a study was undertaken with a model denitrifying bacterium Paracoccus denitrificans PD1222. Extracellular nitrite inhibits aerobic growth of P. denitrificans in a pH-dependent manner that is likely to be a result of both nitrite and free nitrous acid (pKa = 3.25) and subsequent reactive nitrogen oxides generated from the intracellular passage of FNA into P. denitrificans. Increased expression of a gene encoding a flavohemoglobin protein (Fhp) (Pden_1689) was observed in response to extracellular nitrite. Construction and analysis of a deletion mutant established Fhp to be involved in endowing nitrite/FNA resistance at high extracellular nitrite concentrations. Global transcriptional analysis confirmed nitrite-dependent expression of fhp and indicated that P. denitrificans expressed a number of stress response systems associated with protein, DNA and lipid repair. It is therefore suggested that nitrite causes a pH-dependent stress response that is due to the production of associated reactive nitrogen species, such as nitric oxide from the internalisation of FNA.

  8. The Hepatoprotective Effect of Sodium Nitrite on Cold Ischemia-Reperfusion Injury

    Directory of Open Access Journals (Sweden)

    Wei Li

    2012-01-01

    Full Text Available Liver ischemia-reperfusion injury is a major cause of primary graft non-function or initial function failure post-transplantation. In this study, we examined the effects of sodium nitrite supplementation on liver IRI in either Lactated Ringer's (LR solution or University of Wisconsin (UW solution. The syngeneic recipients of liver grafts were also treated with or without nitrite by intra-peritoneal injection. Liver AST and LDH release were significantly reduced in both nitrite-supplemented LR and UW preservation solutions compared to their controls. The protective effect of nitrite was more efficacious with longer cold preservation times. Liver histological examination demonstrated better preserved morphology and architecture with nitrite treatment. Hepatocellular apoptosis was significantly reduced in the nitrite-treated livers compared their controls. Moreover, liver grafts with extended cold preservation time of 12 to 24 hours demonstrated improved liver tissue histology and function post-reperfusion with either the nitrite-supplemented preservation solution or in nitrite-treated recipients. Interestingly, combined treatment of both the liver graft and recipient did not confer protection. Thus, nitrite treatment affords significant protection from cold ischemic and reperfusion injury to donor livers and improves liver graft acute function post-transplantation. The results from this study further support the potential for nitrite therapy to mitigate ischemia-reperfusion injury in solid organ transplantation.

  9. The effect of environmental hypercapnia and size on nitrite toxicity in the striped catfish (Pangasianodon hypophthalmus)

    DEFF Research Database (Denmark)

    Hvas, Malthe; Damsgaard, Christian; Gam, Le Thi Hong

    2016-01-01

    Striped catfish (Pangasianodon hypophthalmus) are farmed intensively at high stocking densities in Vietnam where they are likely to encounter environmental hypercapnia as well as occasional high levels of aquatic nitrite. Nitrite competes with Cl- for uptake at the branchial HCO3-/Cl- exchanger...... in the initial phase of acid-base compensation. Overall, longer term environmental hypercapnia does not protect against nitrite uptake in P. hypophthalmus, but instead enhances it. In addition, we observed a significant size effect in nitrite accumulation, where large fish attained plasma [nitrite] above...... the ambient concentration, while small fish did not. Small P. hypophthalmus instead had significantly higher plasma [nitrate], and haemoglobin concentrations, revealing greater capacity for detoxifying nitrite by oxidising it to nitrate....

  10. Measurement of nitrite reductase in leaf tissue of Vigna mungo : A new method.

    Science.gov (United States)

    Srivastava, R C; Bose, B; Mukerji, D; Mathur, S N; Srivastava, H S

    1979-12-01

    The enzyme nitrite reductase (EC 1.6.6.4) is generally assayed in terms of disappearance of nitrite from the assay medium. We describe a technique which allowed estimation of the enzyme level in leaf tissues of Vigna mungo (L). Hepper in terms of the release of the product (NH3) of the enzyme reaction. The technique is offered as an alternative, possibly more convenient method for assay of nitrite reductase in plant tissue in vivo.

  11. Nitrate reduction to nitrite, nitric oxide and ammonia by gut bacteria under physiological conditions.

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

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

    2017-02-17

    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 NaN3 can inhibit nitrite oxidation effectively; meanwhile, the nitrite denitrification with N2O 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 H2O to oxidize nitrite under anaerobic conditions. Proteobacteria might play a major role in the process of denitrification in MFC.

  14. METHOD FOR NITRATE DETERMINATION IN WATER IN THE PRESENCE OF NITRITE

    Directory of Open Access Journals (Sweden)

    Maria Sandu

    2014-12-01

    Full Text Available The study relates to determination of nitrate in presence of nitrite in water and can be used in the quality monitoring of natural water (surface and groundwater, drinking water, water from fish farms and public aquaria where autonomous filters is used. The nature and quantity of reagents used have insignificant impact on natural waters and sewages. According to the investigation, the method includes the removal of nitrite from the solution/water with sulfaminic acid, the nitrate ion reduction to nitrite using a reducing mixture that contains Na2SO4 and zinc dust in ratio of 100:5 and determining the nitrite with the Griess reagent.

  15. Role of Nitrite in Processed Meat Products and its Degradation during their Storage

    Directory of Open Access Journals (Sweden)

    ILIRJANA BOCI

    2014-06-01

    Full Text Available This paper represents the analytical data of nitrite level obtained from the experimental work done on meat processed samples taken from a meat processing plant in Tirana. There has been a long debate and health concern about the nitrite content in meat products. Nitrite is added to e.g. sausages, and hams and other meat products to preserve these products and keep them free from dangerous bacteria. Among the aims are preventing botulism, a dangerous food poison. But also it’s important to use the smallest possible amount of nitrite as a preservative because nitrite in meat can also form nitrosamines, which can damage the health. That’s why the role of nitrite in processed meat and its recommended level conform to new EC Regulations are given in the introduction part of this paper. It is important that the nitrite level be monitored during all the processing steps up to the end consumers. This makes the objective of this paper. It gives the analytical data on nitrite level on meat processed samples taken and tested during their storage and ripening period of time. Different kinds of meat products are taken and tested to evaluate the influence of various parameters (storage time, time until to the end consumers, various kinds of packing in the degradation rate of ingoing nitrite.

  16. Effect of Nitrite Inhibitor on the Macrocell Corrosion Behavior of Reinforcing Steel

    Directory of Open Access Journals (Sweden)

    Zhonglu Cao

    2015-01-01

    Full Text Available The effect of nitrite ions on the macrocell corrosion behavior of reinforcing steel embedded in cement mortar was investigated by comparing and analyzing the macrocell corrosion current, macrocell polarization ratios, and slopes of anodic and cathodic steels. Based on the experimental results, the relationship between macrocell potential difference and macrocell current density was analyzed, and the mechanism of macrocell corrosion affected by nitrite ions was proposed. The results indicated that nitrite ions had significant impact on the macrocell polarization ratios of cathode and anode. The presence of nitrite could reduce the macrocell current by decreasing the macrocell potential difference and increasing the macrocell polarization resistance of the anode.

  17. Nitrite toxicity of Litopenaeus vannamei in water containing low concentrations of sea salt or mixed salts

    Science.gov (United States)

    Sowers, A.; Young, S.P.; Isely, J.J.; Browdy, C.L.; Tomasso, J.R.

    2004-01-01

    The uptake, depuration and toxicity of environmental nitrite was characterized in Litopenaeus vannamei exposed in water containing low concentrations of artificial sea salt or mixed salts. In 2 g/L artificial sea salts, nitrite was concentrated in the hemolymph in a dose-dependent and rapid manner (steady-state in about 2 d). When exposed to nitrite in 2 g/L artificial sea salts for 4 d and then moved to a similar environment without added nitrite, complete depuration occurred within a day. Increasing salinity up to 10 g/L decreased uptake of environmental nitrite. Nitrite uptake in environments containing 2 g/L mixed salts (combination of sodium, potassium, calcium and magnesium chlorides) was similar to or lower than rates in 2 g/L artificial sea salt. Toxicity was inversely related to total dissolved salt and chloride concentrations and was highest in 2 g/L artificial sea salt (96-h medial lethal concentration = 8.4 mg/L nitrite-N). Animals that molted during the experiments did not appear to be more susceptible to nitrite than animals that did not molt. The shallow slope of the curve describing the relationship between toxicity and salinity suggests that management of nitrite toxicity in low-salinity shrimp ponds by addition of more salts may not be practical. ?? Copyright by the World Aquaculture Society 2004.

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

    Science.gov (United States)

    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.

  19. Excessive nitrite affects zebrafish valvulogenesis through yielding too much NO signaling.

    Directory of Open Access Journals (Sweden)

    Junbo Li

    Full Text Available Sodium nitrite, a common food additive, exists widely not only in the environment but also in our body. Excessive nitrite causes toxicological effects on human health; however, whether it affects vertebrate heart valve development remains unknown. In vertebrates, developmental defects of cardiac valves usually lead to congenital heart disease. To understand the toxic effects of nitrite on valvulogenesis, we exposed zebrafish embryos with different concentrations of sodium nitrite. Our results showed that sodium nitrite caused developmental defects of zebrafish heart dose dependently. It affected zebrafish heart development starting from 36 hpf (hour post fertilization when heart initiates looping process. Comprehensive analysis on the embryos at 24 hpf and 48 hpf showed that excessive nitrite did not affect blood circulation, vascular network, myocardium and endocardium development. But development of endocardial cells in atrioventricular canal (AVC of the embryos at 48 hpf was disrupted by too much nitrite, leading to defective formation of primitive valve leaflets at 76 hpf. Consistently, excessive nitrite diminished expressions of valve progenitor markers including bmp4, has2, vcana and notch1b at 48 hpf. Furthermore, 3', 5'-cyclic guanosine monophosphate (cGMP, downstream of nitric oxide (NO signaling, was increased its level significantly in the embryos exposed with excessive nitrite and microinjection of soluble guanylate cyclase inhibitor ODQ (1H-[1], [2], [4]Oxadiazolo[4,3-a] quinoxalin-1-one, an antagonist of NO signaling, into nitrite-exposed embryos could partly rescue the cardiac valve malformation. Taken together, our results show that excessive nitrite affects early valve leaflet formation by producing too much NO signaling.

  20. The effect of environmental hypercapnia and size on nitrite toxicity in the striped catfish (Pangasianodon hypophthalmus).

    Science.gov (United States)

    Hvas, Malthe; Damsgaard, Christian; Gam, Le Thi Hong; Huong, Do Thi Thanh; Jensen, Frank B; Bayley, Mark

    2016-07-01

    Striped catfish (Pangasianodon hypophthalmus) are farmed intensively at high stocking densities in Vietnam where they are likely to encounter environmental hypercapnia as well as occasional high levels of aquatic nitrite. Nitrite competes with Cl(-) for uptake at the branchial HCO3(-)/Cl(-) exchanger, causing a drastic reduction in the blood oxygen carrying capacity through the formation of methaemoglobin and nitrosylhaemoglobin. Environmental hypercapnia induces a respiratory acidosis where the branchial HCO3(-)/Cl(-) exchange activity is reduced in order to retain HCO3(-) for pH recovery, which should lead to a reduced nitrite uptake. To assess the effect of hypercapnia on nitrite uptake, fish were cannulated in the dorsal aorta, allowing repeated blood sampling for measurements of haemoglobin derivatives, plasma ions and acid-base status during exposure to 0.9mM nitrite alone and in combination with acute and 48h acclimated hypercapnia over a period of 72h. Nitrite uptake was initially reduced during the hypercapnia-induced acidosis, but after pH recovery the situation was reversed, resulting in higher plasma nitrite concentrations and lower functional haemoglobin levels that eventually caused mortality. This suggests that branchial HCO3(-)/Cl(-) exchange activity is reduced only during the initial acid-base compensation, but subsequently increases with the greater availability of internal HCO3(-) counter-ions as pH is compensated. The data further suggest that branchial Na(+)/H(+) exchange plays a significant role in the initial phase of acid-base compensation. Overall, longer term environmental hypercapnia does not protect against nitrite uptake in P. hypophthalmus, but instead enhances it. In addition, we observed a significant size effect in nitrite accumulation, where large fish attained plasma [nitrite] above the ambient concentration, while small fish did not. Small P. hypophthalmus instead had significantly higher plasma [nitrate], and haemoglobin

  1. Acrylic microspheres-based optosensor for visual detection of nitrite.

    Science.gov (United States)

    Noor, Nur Syarmim Mohamed; Tan, Ling Ling; Heng, Lee Yook; Chong, Kwok Feng; Tajuddin, Saiful Nizam

    2016-09-15

    A new optosensor for visual quantitation of nitrite (NO2(-)) ion has been fabricated by physically immobilizing Safranine O (SO) reagent onto a self-adhesive poly(n-butyl acrylate) [poly(nBA)] microspheres matrix, which was synthesized via facile microemulsion UV lithography technique. Evaluation and optimization of the optical NO2(-) ion sensor was performed with a fiber optic reflectance spectrophotometer. Scanning electron micrograph showed well-shaped and smooth spherical morphology of the poly(nBA) microspheres with a narrow particles size distribution from 0.6 μm up to 1.8 μm. The uniform size distribution of the acrylic microspheres promoted homogeneity of the immobilized SO reagent molecules on the microspheres' surfaces, thereby enhanced the sensing response reproducibility (<5% RSD) with a linear range obtained from 10 to 100 ppm NO2(-) ion. The micro-sized acrylic immobilization matrix demonstrated no significant barrier for diffusion of reactant and product, and served as a good solid state ion transport medium for reflectometric nitrite determination in food samples.

  2. Sugar-driven prebiotic synthesis of ammonia from nitrite.

    Science.gov (United States)

    Weber, Arthur L

    2010-06-01

    Reaction of 3-5 carbon sugars, glycolaldehyde, and alpha-ketoaldehydes with nitrite under mild anaerobic aqueous conditions yielded ammonia, an essential substrate for the synthesis of nitrogen-containing molecules during abiogenesis. Under the same conditions, ammonia synthesis was not driven by formaldehyde, glyoxylate, 2-deoxyribose, and glucose, a result indicating that the reduction process requires an organic reductant containing either an accessible alpha-hydroxycarbonyl group or an alpha-dicarbonyl group. Small amounts of aqueous Fe(+3) catalyzed the sugar-driven synthesis of ammonia. The glyceraldehyde concentration dependence of ammonia synthesis, and control studies of ammonia's reaction with glyceraldehyde, indicated that ammonia formation is accompanied by incorporation of part of the synthesized ammonia into sugar-derived organic products. The ability of sugars to drive the synthesis of ammonia is considered important to abiogenesis because it provides a way to generate photochemically unstable ammonia at sites of sugar-based origin-of-life processes from nitrite, a plausible prebiotic nitrogen species.

  3. Addition of nitrite enhances the electrochemical defluorination of 2-fluoroaniline.

    Science.gov (United States)

    Feng, Huajun; Liang, Yuxiang; Guo, Kun; Long, Yuyang; Cong, Yanqing; Shen, Dongsheng

    2015-12-30

    This study introduces a novel approach that uses the interaction of pollutants with added nitrite to produce diazonium salts, which cause in situ self-assembly of the pollutants on carbon electrodes, to improve their 2-fluoroaniline (2-FA) defluorination and removal performance. The 2-FA degradation performance, electrode properties, electrochemical properties and degradation pathway were investigated. The reactor containing NO2(-) achieved a 2-FA removal efficiency of 90.1% and a defluorination efficiency of 38% within 48 h, 1.4 and 2.3 times higher than the corresponding results achieved without NO2(-), respectively. The residual NO2(-) was less than 0.5mg/L in the reactor containing added NO2(-), which would not cause serious secondary pollution. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) results proved that the carbon anode surface was successfully modified with benzene polymer, and electrochemical tests confirmed that the electrochemical activity of the modified anode was enhanced significantly. The C-F bond was weakened by the effect of the positive charge of the benzenediazonium groups, and the high electrochemical activity of the carbon anode enhanced the electrochemical performance of the system to accelerate defluorination. Thus, the present electrical method involving nitrite nitrogen is very promising for the treatment of wastewater containing fluoroaniline compounds.

  4. Method 353.4 Determination of Nitrate and Nitrite in Estuarine and Coastal Waters by Gas Segmented Continuous Flow Colorimetric Analysis

    Science.gov (United States)

    This method provides a procedure for determining nitrate and nitrite concentrations in estuarine and coastal waters. Nitrate is reduced to nitrite by cadmium,1-3 and the resulting nitrite determined by formation of an azo dye.4-6

  5. Haematological and ion regulatory effects of nitrite in the air-breathing snakehead fish Channa striata

    DEFF Research Database (Denmark)

    Lefevre, Sjannie; Jensen, Frank Bo; Huong, Do T.T.;

    2012-01-01

    The tolerance and effects of nitrite on ion balance and haematology were investigated in the striped snakehead, Channa striata Bloch 1793, which is an air-breathing fish with reduced gills of importance for aquaculture in South East Asia. C. striata was nitrite tolerant with a 96 h LC50 of 4.7 m...

  6. 77 FR 71006 - Sodium Nitrite Injection and Sodium Thiosulfate Injection Drug Products Labeled for the Treatment...

    Science.gov (United States)

    2012-11-28

    ... HUMAN SERVICES Food and Drug Administration [Docket No. FDA-2012-N-1134 Sodium Nitrite Injection and Sodium Thiosulfate Injection Drug Products Labeled for the Treatment of Cyanide Poisoning; Enforcement... products containing sodium nitrite labeled for the treatment of cyanide poisoning and unapproved...

  7. Red wine-dependent reduction of nitrite to nitric oxide in the stomach.

    Science.gov (United States)

    Gago, Bruno; Lundberg, Jon O; Barbosa, Rui M; Laranjinha, João

    2007-11-01

    Nitrite may be a source for nitric oxide (*NO), particularly in highly acidic environments, such as the stomach. Diet products contribute also with reductants that dramatically increase the production of *NO from nitrite. Red wine has been attributed health promoting properties largely on basis of the reductive antioxidant properties of its polyphenolic fraction. We show in vitro that wine, wine anthocyanin fraction and wine catechol (caffeic acid) dose- and pH-dependently promote the formation of *NO when mixed with nitrite, as measured electrochemically. The production of *NO promoted by wine from nitrite was substantiated in vivo in healthy volunteers by measuring *NO in the air expelled from the stomach, following consumption of wine, as measured by chemiluminescence. Mechanistically, the reaction involves the univalent reduction of nitrite, as suggested by the formation of *NO and by the appearance of EPR spectra assigned to wine phenolic radicals. Ascorbic and caffeic acids cooperate in the reduction of nitrite to *NO. Moreover, reduction of nitrite is critically dependent on the phenolic structure and nitro-derivatives of phenols are also formed, as suggested by caffeic acid UV spectral modifications. The reduction of nitrite may reveal previously unrecognized physiologic effects of red wine in connection with *NO bioactivity.

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

    Science.gov (United States)

    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.

  9. THE DECOMPOSITION OF DIETHYL PEROXIDE IN THE PRESENCE OF NITRIC OXIDE AND ETHYL NITRITE

    Science.gov (United States)

    substantial amounts. Studies were made of the reactions of ethoxyl radicals (produced by the decomposition of diethyl peroxide at 181 deg C) with ethyl nitrite...and NO. The reaction rate between the ethoxyl radicals and NO was much greater than that between the radicals the nitrite.

  10. Protection of Steel Corrosion in Concrete Members by the Combination of Galvanic Anode and Nitrite Penetration

    OpenAIRE

    Minobu Aoyama; Shinichi Miyazato; Mitsunori Kawamura

    2014-01-01

    Chloride induced-corrosion of steel bars in concrete can make cracks and exfoliation in near-surface regions in reinforced concrete structures. In this paper, we described the basic concept and practice of steel bars corrosion protection method by the combination of galvanic anode (zinc wire) and the penetration of nitrite ions from mortar layers containing a large amount of lithium nitrite.

  11. Autotrophic denitrification for nitrate and nitrite removal using sulfur-limestone

    Institute of Scientific and Technical Information of China (English)

    Weili Zhou; Yeiue Sun; Bingtao Wu; Yue Zhang; Min Huang; Toshiaki Miyanaga; Zhenjia Zhang

    2011-01-01

    Sulfur-limestone was used in the autotrophic denitrification process to remove the nitrate and nitrite in a lab scale upflow biofilter.Synthetic water with four levels of nitrate and nitrite concentrations of 10,40,70 and 100 mg N/L was tested.When treating the low concentration of nitrate- or nitrite-contaminated water (10,40 mg N/L),a high removal rate of about 90% was achieved at the hydraulic retention time (HRT) of 3 hr and temperature of 20-25℃.At the same HRT,50% of the nitrate or nitrite could be removed even at the low temperature of 5-10℃.For the higher concentration nitrate and nitrite (70,100 mg N/L),longer HRT was required.The batch test indicated that influent concentration,HRT and temperature are important factors affecting the denitrification efficiency.Molecular analysis implied that nitrate and nitrite were denitrified into nitrogen by the same microorganisms.The sequential two-stepreactions from nitrate to nitrite and from nitrite to the next-step product might have taken place in the same cell during the autotrophic denitrification process.

  12. 78 FR 39316 - Sodium Nitrite From China and Germany; Institution of Five-Year Reviews

    Science.gov (United States)

    2013-07-01

    ... (Review)] Sodium Nitrite From China and Germany; Institution of Five-Year Reviews AGENCY: United States... and the antidumping duty order on sodium nitrite from Germany would be likely to lead to continuation... Management and Budget (OMB) number is not displayed; the OMB number is 3117-0016/USITC No....

  13. Sodium nitrite protects against kidney injury induced by brain death and improves post-transplant function.

    Science.gov (United States)

    Kelpke, Stacey S; Chen, Bo; Bradley, Kelley M; Teng, Xinjun; Chumley, Phillip; Brandon, Angela; Yancey, Brett; Moore, Brandon; Head, Hughston; Viera, Liliana; Thompson, John A; Crossman, David K; Bray, Molly S; Eckhoff, Devin E; Agarwal, Anupam; Patel, Rakesh P

    2012-08-01

    Renal injury induced by brain death is characterized by ischemia and inflammation, and limiting it is a therapeutic goal that could improve outcomes in kidney transplantation. Brain death resulted in decreased circulating nitrite levels and increased infiltrating inflammatory cell infiltration into the kidney. Since nitrite stimulates nitric oxide signaling in ischemic tissues, we tested whether nitrite therapy was beneficial in a rat model of brain death followed by kidney transplantation. Nitrite, administered over 2 h of brain death, blunted the increased inflammation without affecting brain death-induced alterations in hemodynamics. Kidneys were transplanted after 2 h of brain death and renal function followed over 7 days. Allografts collected from nitrite-treated brain-dead rats showed significant improvement in function over the first 2 to 4 days after transplantation compared with untreated brain-dead animals. Gene microarray analysis after 2 h of brain death without or with nitrite therapy showed that the latter significantly altered the expression of about 400 genes. Ingenuity Pathway Analysis indicated that multiple signaling pathways were affected by nitrite, including those related to hypoxia, transcription, and genes related to humoral immune responses. Thus, nitrite therapy attenuates brain death-induced renal injury by regulating responses to ischemia and inflammation, ultimately leading to better post-transplant kidney function.

  14. Nitrite in processed meat products in Khartoum, Sudan and dietary intake

    NARCIS (Netherlands)

    Adam, Aziza Hussein Bakheit; Mustafa, Nazik Eltayeb Musa; Rietjens, Ivonne M.C.M.

    2016-01-01

    Nitrite intake from locally processed meat in Khartoum, Sudan was estimated and compared to established safety levels. For this purpose, 90 locally processed meat samples were collected randomly from retail outlets and analysed for nitrite levels according to the British standard 1992 protocol and 3

  15. Automated simultaneous monitoring of nitrate and nitrite in surface water by sequential injection analysis.

    Science.gov (United States)

    Legnerová, Zlatuse; Solich, Petr; Sklenárová, Hana; Satínský, Dalibor; Karlícek, Rolf

    2002-06-01

    A fully automated procedure based on Sequential Injection Analysis (SIA) methodology for simultaneous monitoring of nitrate and nitrite in surface water samples is described. Nitrite was determined directly using the Griess diazo-coupling reaction and the formed azo dye was measured at 540 nm in the flow cell of the fibre-optic spectrophotometer. Nitrate zone was passed through a reducing mini-column containing copperised-cadmium. After the reduction of nitrate into nitrite the sample was aspirated by flow reversal to the holding coil, treated with the reagent and finally passed through the flow cell. The calibration curve was linear over the range 0.05-1.00 mg N l(-1) of nitrite and 0.50-50.00 mg N l(-1) of nitrate; correlation coefficients were 0.9993 and 0.9988 for nitrite and nitrate, respectively. Detection limits were 0.015 and 0.10 mg N l(-1) for nitrite and nitrate, respectively. The relative standard deviation (RSD) values (n = 3) were 1.10% and 1.32% for nitrite and nitrate, respectively. The total time of one measuring cycle was 250 s, thus the sample throughput was about 14 h(-1). Nitrate and nitrite were determined in the real samples of surface water, and the results have been compared with those obtained by two other flow methods; flow injection analysis based on the same reactions and isotachophoretic determination used in a routine environmental control laboratory.

  16. Measurements of nitrite production and nitrite-producing organisms in and around the primary nitrite maximum in the central California Current

    Directory of Open Access Journals (Sweden)

    A. E. Santoro

    2013-03-01

    Full Text Available Nitrite (NO2– is a substrate for both oxidative and reductive microbial metabolism. NO2– accumulates at the base of the euphotic zone in oxygenated, stratified open ocean water columns, forming a feature known as the primary nitrite maximum (PNM. Potential pathways of NO2– production include the oxidation of ammonia (NH3 by ammonia-oxidizing bacteria or archaea and assimilatory nitrate (NO3– reduction by phytoplankton or heterotrophic bacteria. Measurements of NH3 oxidation and NO3– reduction to NO2– were conducted at two stations in the central California Current in the eastern North Pacific to determine the relative contributions of these processes to NO2– production in the PNM. Sensitive (−1, high-resolution measurements of [NH4+] and [NO2–] indicated a persistent NH4+ maximum overlying the PNM at every station, with concentrations as high as 1.5 μmol L−1. Within and just below the PNM, NH3 oxidation was the dominant NO2– producing process with rates of NH3 oxidation of up to 50 nmol L−1 d−1, coinciding with high abundances of ammonia-oxidizing archaea. Though little NO2– production from NO3– was detected, potentially nitrate-reducing phytoplankton (photosynthetic picoeukaryotes, Synechococcus, and Prochlorococcus were present at the depth of the PNM. Rates of NO2– production from NO3– were highest within the upper mixed layer (4.6 nmol L−1 d−1 but were either below detection limits or 10 times lower than NH3 oxidation rates around the PNM. One-dimensional modeling of water column NO2– profiles supported direct rate measurements of a net biological sink for NO2– just below the PNM. Residence time estimates of NO2– within the PNM were similar at the mesotrophic and oligotrophic stations and ranged from 150–205 d. Our results suggest the PNM is a dynamic, rather than relict, feature with a source term dominated by ammonia oxidation.

  17. Crystal structure of the catalytic domain of PigE: a transaminase involved in the biosynthesis of 2-methyl-3-n-amyl-pyrrole (MAP) from Serratia sp. FS14.

    Science.gov (United States)

    Lou, Xiangdi; Ran, Tingting; Han, Ning; Gao, Yanyan; He, Jianhua; Tang, Lin; Xu, Dongqing; Wang, Weiwu

    2014-04-25

    Prodigiosin, a tripyrrole red pigment synthesized by Serratia and some other microbes through a bifurcated biosynthesis pathway, MBC (4-methoxy-2,2'-bipyrrole-5-carbaldehyde) and MAP (2-methyl-3-n-amyl-pyrrole) are synthesized separately and then condensed by PigC to form prodigiosin. MAP is synthesized sequentially by PigD, PigE and PigB. PigE catalyzes the transamination of an amino group to the aldehyde group of 3-acetyloctanal, resulting in an aminoketone, which spontaneously cyclizes to form H2MAP. Here we report the crystal structure of the catalytic domain of PigE which involved in the biosynthesis of prodigiosin precursor MAP for the first time to a resolution of 2.3Å with a homodimer in the asymmetric unit. The monomer of PigE catalytic domain is composed of three domains with PLP as cofactor: a small N-terminal domain connecting the catalytic domain with the front part of PigE, a large PLP-binding domain and a C-terminal domain. The residues from both monomers build the PLP binding site at the interface of the dimer which resembles the other PLP-dependent enzymes. Structural comparison of PigE with Thermus thermophilus AcOAT showed a higher hydrophobic and smaller active site of PigE, these differences may be the reason for substrate specificity.

  18. Co-extraction and co-stripping of U(VI) and Pu(IV) using tri-iso-amyl phosphate and tri-n-butyl phosphate in n-dodecane from nitric acid media under high loading conditions

    Energy Technology Data Exchange (ETDEWEB)

    Sreenivasulu, Balija; Suresh, Ammath; Sivaraman, Nagarajan; Rao, P.R. Vasudeva [Indira Gandhi Centre for Atomic Research, Kalpakkam (India). Chemistry Group

    2016-08-01

    The extraction of Pu(IV) using 1.1 M solution of tri-iso-amyl phosphate (TiAP)/n-dodecane (DD) from plutonium nitrate solutions in nitric acid media was examined as a function of equilibrium aqueous phase metal ion concentration and equilibrium aqueous phase acidity at 303 K. The nitric acid concentration in the organic phase was measured as a function of equilibrium organic phase plutonium concentration. The co-extraction of U(VI) and Pu(IV) was studied using 1.1 M TiAP/DD system as a function of their equilibrium aqueous phase metal ion concentration and compared with 1.1 M tri-n-butyl phosphate (TBP)/n-DD system under identical conditions. Co-extraction and co-stripping of U(VI) and Pu(IV) were studied using 1.1 M TiAP/DD and 1.1 M TBP/DD systems in cross current mode to evaluate the number of stages required for the extraction and stripping of heavy metal ions (uranium and plutonium). The extraction and stripping efficiencies were calculated for both the systems. The saturation limit of the organic phase was also established in these studies.

  19. Vapor intrusion risk of fuel ether oxygenates methyl tert-butyl ether (MTBE), tert-amyl methyl ether (TAME) and ethyl tert-butyl ether (ETBE): A modeling study.

    Science.gov (United States)

    Ma, Jie; Xiong, Desen; Li, Haiyan; Ding, Yi; Xia, Xiangcheng; Yang, Yongqi

    2017-06-15

    Vapor intrusion of synthetic fuel additives represents a critical yet still neglected problem at sites contaminated by petroleum fuel releases. This study used an advanced numerical model to investigate the vapor intrusion potential of fuel ether oxygenates methyl tert-butyl ether (MTBE), tert-amyl methyl ether (TAME), and ethyl tert-butyl ether (ETBE). Simulated indoor air concentration of these compounds can exceed USEPA indoor air screening level for MTBE (110μg/m(3)). Our results also reveal that MTBE has much higher chance to cause vapor intrusion problems than TAME and ETBE. This study supports the statements made by USEPA in the Petroleum Vapor Intrusion (PVI) Guidance that the vertical screening criteria for petroleum hydrocarbons may not provide sufficient protectiveness for fuel additives, and ether oxygenates in particular. In addition to adverse impacts on human health, ether oxygenate vapor intrusion may also cause aesthetic problems (i.e., odour and flavour). Overall, this study points out that ether oxygenates can cause vapor intrusion problems. We recommend that USEPA consider including the field measurement data of synthetic fuel additives in the existing PVI database and possibly revising the PVI Guidance as necessary.

  20. Determination of low level methyl tert-butyl ether, ethyl tert-butyl ether and methyl tert-amyl ether in human urine by HS-SPME gas chromatography/mass spectrometry.

    Science.gov (United States)

    Scibetta, Licia; Campo, Laura; Mercadante, Rosa; Foà, Vito; Fustinoni, Silvia

    2007-01-02

    Methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE) and tert-amyl methyl ether (TAME) are oxygenated compounds added to gasoline to enhance octane rating and to improve combustion. They may be found as pollutants of living and working environments. In this work a robotized method for the quantification of low level MTBE, ETBE and TAME in human urine was developed and validated. The analytes were sampled in the headspace of urine by SPME in the presence of MTBE-d12 as internal standard. Different fibers were compared for their linearity and extraction efficiency: carboxen/polydimethylsiloxane, polydimethylsiloxane/divinylbenzene, and polydimethylsiloxane. The first, although highly efficient, was discarded due to deviation of linearity for competitive displacement, and the polydimethylsiloxane/divinylbenzene fiber was chosen instead. The analysis was performed by GC/MS operating in the electron impact mode. The method is very specific, with range of linearity 30-4600 ng L(-1), within- and between-run precision, as coefficient of variation, ethers was evaluated analysing the specimens of seven traffic policemen exposed to autovehicular emissions: using the calibration curve and the method of standard additions comparable levels of MTBE (68-528 ng L(-1)), ETBE (<6 ng L(-1)), and TAME (<6 ng L(-1)) were obtained.

  1. Single-walled carbon nanotubes as an effective adsorbent in solid-phase microextraction of low level methyl tert-butyl ether, ethyl tert-butyl ether and methyl tert-amyl ether from human urine.

    Science.gov (United States)

    Rastkari, Noushin; Ahmadkhaniha, Reza; Yunesian, Masud

    2009-05-15

    Carbon nanotubes (CNTs) are a kind of new carbon-based nano-materials which have drawn great attention in many application fields. The potential single-walled carbon nanotubes (SWCNTs) as solid-phase microextraction (SPME) adsorbents for the preconcentration of environmental pollutants have been investigated in recent years. The goal of this work was to investigate the feasibility of SWCNTs used as adsorbents for solid-phase microextraction of methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE) and tert-amyl methyl ether (TAME) in human urine. SWCNTs were attached onto a stainless steel wire through organic binder. Potential factors affecting the extraction efficiency were optimized, including extraction time, extraction temperature, desorption time, desorption temperature, and salinity. The developed method showed good performance according to the ICH performance criteria for bioanalytical methods. The calibration curves of the ethers were linear (r(2)>or=0.992) in the range from 10 to 5000 ng L(-1). The limits of detection at a signal-to-noise (S/N) ratio of 3 were 10 ng L(-1) for all the analytes. In addition, compared with the commercial carboxen/polydimethylsiloxane (CAR/PDMS) fiber, the SWCNT fiber showed better thermal stability (over 350 degrees C) and longer life span (over 150 times). The developed method was applied successfully to determine trace level of the ethers in urine of 10 healthy male volunteers.

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

    Science.gov (United States)

    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 (Psausages 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.

  3. Ammonium and nitrite oxidation at nanomolar oxygen concentrations in oxygen minimum zone waters.

    Science.gov (United States)

    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

    2016-09-20

    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 (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.

  4. Effect of anaerobic digestion on the high rate of nitritation, treating piggery wastewater

    Institute of Scientific and Technical Information of China (English)

    Jiyeol Im; Kyungik Gil

    2011-01-01

    The amount of piggery wastewater as domestic livestock is increasing.The volume of piggery wastewater produced is less than the volume of other wastewaters,but piggery wastewater has a heavy impact on wastewater streams due to an extremely high concentration of nitrogen and COD.In this study,laboratory reactors were operated using piggery wastewater and the effluent of anaerobic digester from piggery wastewater plants.The purpose of this study was to induce the nitritation process,which is an economically advantageous nitrogen removal method that converts ammonium nitrogen into nitrite.The results showed that the effluent of anaerobic digester from piggery wastewater was more efficient than raw piggery wastewater in terms of inducing nitritation.It can be deduced that nitritation is largely affected by an organic fraction of piggery wastewater.It can also be concluded that a small amount of biodegradable organic matter in piggery wastewater is efficient in inducing nitritation.

  5. Effect of sodium ascorbate and sodium nitrite on protein and lipid oxidation in dry fermented sausages.

    Science.gov (United States)

    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.

  6. Antimicrobial effect of acidified nitrate and nitrite on six common oral pathogens in vitro

    Institute of Scientific and Technical Information of China (English)

    XIA Deng-sheng; LIU Yin; ZHANG Chun-mei; YANG Sheng-hui; WANG Song-lin

    2006-01-01

    Background Salivary nitrate is positively correlated with plasma nitrate and its level is 9 times the plasma level after nitrate loading. Nitrate in saliva is known to be reduced to nitrite by oral bacteria. Nitrate and nitrite levels in saliva are 3-5 times those in serum in physiological conditions respectively in our previous study. The biological functions of high salivary nitrate and nitrite are still not well understood. The aim of this in vitro study was to investigate the antimicrobial effects of nitrate and nitrite on main oral pathogens under acidic conditions.Methods Six common oral pathogens including Streptococcus mutans NCTC 10449, Lactobacillus acidophilus ATCC 4646, Porphyromonas gingivalis ATCC 33277, Capnocytophaga gingivalis ATCC 33624, Fusobacterium nucleatum ATCC 10953, and Candida albicans ATCC 10231 were cultured in liquid medium. Sodium nitrate or sodium nitrite was added to the medium to final concentrations of 0, 0.5, 1, 2, and 10 mmol/L. All of the microorganisms were incubated for 24 to 48 hours. The optical densities (OD) of cell suspensions were determined and the cultures were transferred to solid nutrient broth medium to observe the minimum inhibitory concentration and minimum bactericidal/fungicidal concentration for the six tested pathogens.Results Nitrite at concentrations of 0.5 to 10 mmol/L had an inhibitory effect on all tested organisms at low pH values. The antimicrobial effect of nitrite increased with the acidity of the medium. Streptococcus mutans NCTC 10449 was highly sensitive to nitrite at low pH values. Lactobacillus acidophilus ATCC 4646 and Candida albicans ATCC 10231 were relatively resistant to acidified nitrite. Nitrate at the given concentrations and under acidic conditions had no inhibitory effect on the growth of any of the tested pathogens.Conclusion Nitrite, at a concentration equal to that in human saliva, is both cytocidal and cytostatic to six principal oral pathogens in vitro, whereas nitrate at a similar

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

    Directory of Open Access Journals (Sweden)

    Dong-mei Liu

    Full Text Available 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(+.

  8. Crosstalk between nitrite, myoglobin and reactive oxygen species to regulate vasodilation under hypoxia.

    Science.gov (United States)

    Totzeck, Matthias; Hendgen-Cotta, Ulrike B; Kelm, Malte; Rassaf, Tienush

    2014-01-01

    The systemic response to decreasing oxygen levels is hypoxic vasodilation. While this mechanism has been known for more than a century, the underlying cellular events have remained incompletely understood. Nitrite signaling is critically involved in vessel relaxation under hypoxia. This can be attributed to the presence of myoglobin in the vessel wall together with other potential nitrite reductases, which generate nitric oxide, one of the most potent vasodilatory signaling molecules. Questions remain relating to the precise concentration of nitrite and the exact dose-response relations between nitrite and myoglobin under hypoxia. It is furthermore unclear whether regulatory mechanisms exist which balance this interaction. Nitrite tissue levels were similar across all species investigated. We then investigated the exact fractional myoglobin desaturation in an ex vivo approach when gassing with 1% oxygen. Within a short time frame myoglobin desaturated to 58±12%. Given that myoglobin significantly contributes to nitrite reduction under hypoxia, dose-response experiments using physiological to pharmacological nitrite concentrations were conducted. Along all concentrations, abrogation of myoglobin in mice impaired vasodilation. As reactive oxygen species may counteract the vasodilatory response, we used superoxide dismutase and its mimic tempol as well as catalase and ebselen to reduce the levels of reactive oxygen species during hypoxic vasodilation. Incubation of tempol in conjunction with catalase alone and catalase/ebselen increased the vasodilatory response to nitrite. Our study shows that modest hypoxia leads to a significant nitrite-dependent vessel relaxation. This requires the presence of vascular myoglobin for both physiological and pharmacological nitrite levels. Reactive oxygen species, in turn, modulate this vasodilation response.

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

    Science.gov (United States)

    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.

  10. 78 FR 69646 - Sodium Nitrite From the People's Republic of China: Final Results of the Expedited First Sunset...

    Science.gov (United States)

    2013-11-20

    ... International Trade Administration Sodium Nitrite From the People's Republic of China: Final Results of the... countervailing duty (``CVD'') order on sodium nitrite from the People's Republic of China (``PRC'') would be... sodium nitrite from the PRC, pursuant to section 751(c) of the Tariff Act of 1930, as amended (``the...

  11. 78 FR 69368 - Sodium Nitrite From Germany and the People's Republic of China: Final Results of the Expedited...

    Science.gov (United States)

    2013-11-19

    ... International Trade Administration Sodium Nitrite From Germany and the People's Republic of China: Final Results... reviews of the antidumping duty (``AD'') orders on sodium nitrite from Germany and the People's Republic... nitrite from Germany and the PRC.\\1\\ On July 1, 2013, the Department published the notice of initiation...

  12. 78 FR 68474 - Sodium Nitrite From China And Germany; Scheduling of Expedited Five-Year Reviews Concerning the...

    Science.gov (United States)

    2013-11-14

    ... COMMISSION Sodium Nitrite From China And Germany; Scheduling of Expedited Five-Year Reviews Concerning the... on Sodium Nitrite From Germany AGENCY: United States International Trade Commission. ACTION: Notice... duty order on sodium nitrite from Germany would be likely to lead to continuation or recurrence...

  13. Nitrite attenuated hypochlorous acid-mediated heme degradation in hemoglobin.

    Science.gov (United States)

    Lu, Naihao; Li, Jiayu; Ren, Xiaoming; Tian, Rong; Peng, Yi-Yuan

    2015-08-05

    Hypochlorous acid (HOCl) is elevated in many inflammatory diseases and causes the accumulation of free iron. Through the Fenton reaction, free iron has the ability to generate free radicals and subsequently is toxic. Recent studies have demonstrated that HOCl participates in heme destruction of hemoglobin (Hb) and free iron release. In this study, it was showed that nitrite (NO2(-)) could prevent HOCl-mediated Hb heme destruction and free iron release. Also, NO2(-) prevented HOCl-mediated loss of Hb peroxidase activity. After the NO2(-)/HOCl treatment, Tyr 42 in α-chain was found to be nitrated in Hb, attenuating the electron transferring abilities of phenolic compounds. The protective effects of NO2(-) on HOCl-induced heme destruction were attributed to its reduction of ferryl Hb and/or direct scavenging of HOCl. Therefore, NO2(-) could show protective effects in some inflammatory diseases by preventing HOCl-mediated heme destruction of hemoproteins and free iron release.

  14. Coastal water column ammonium and nitrite oxidation are decoupled in summer

    Science.gov (United States)

    Heiss, Elise M.; Fulweiler, Robinson W.

    2016-09-01

    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 and light. In contrast, nitrite oxidation rates throughout the water column were negatively correlated with light and pH. Multivariate regression analysis revealed that while both surface (20 m) ammonium oxidation rates were most strongly predicted by depth and light, surface rates were also regulated by salinity and deep rates by temperature. Surface (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.

  15. Seasonal Cycle Analysis of the Nitrate Nitrogen and Nitrite Nitrogen in the Bohai Sea

    Institute of Scientific and Technical Information of China (English)

    Shi Qiang; Chen Jianglin; Li Chongde

    2002-01-01

    During 1985~1987, the concentration of nitrate nitrogen was higher in the Laizhou Bay and the Bohai Bay while that of nitrite nitrogen was higher in the Liaodong Bay and the Bohai Bay. The concentration of nitrate nitrogen was highest in winter and lowest in summer while that of nitrite nitrogen was highest in autumn and lowest in spring. The seasonal variation of the concentration of nitrate nitrogen was maximum in the Laizhou Bay and the Bohai Bay while that of the concentration of nitrite nitrogen was maximum in the Liaodong Bay. There was a great difference in the concentration of nitrate nitrogen between the surface and the bottom in autumn and in the concentration of nitrite nitrogen between the surface and the bottom in summer. The main reason for the seasonal variations of the concentration of nitrate nitrogen and nitrite nitrogen was the marine biochemical process. The nitrate nitrogen and nitrite nitrogen in the Bohai Sea basically maintained a quasi-equilibrium state seasonal cycle. The quasi-equilibrium state seasonal cycle of nitrate nitrogen and nitrite nitrogen at the bottom was stable while that at the surface was liable to variations caused by other factors.

  16. Thymoquinone ameliorates testicular tissue inflammation induced by chronic administration of oral sodium nitrite.

    Science.gov (United States)

    Alyoussef, A; Al-Gayyar, M M H

    2016-06-01

    Although sodium nitrite has been widely used as food preservative, building bases of scientific evidence about nitrite continues to oppose the general safety in human health. Moreover, thymoquinone (TQ) has therapeutic potential as antioxidant, anti-inflammatory, antibacterial and anticancer. Therefore, we investigated the effects of both sodium nitrite and TQ on testicular tissues of rats. Forty adult male Sprague Dawley rats were used. They received either 80 mg kg(-1) sodium nitrite or 50 mg kg(-1) TQ daily for twelve weeks. Serum testosterone was measured. Testis were weighed and the testicular tissue homogenates were used for measurements of tumour necrosis factor (TNF)-α, interleukin (IL)-1β, IL-4, IL-6, IL10, caspase-3, caspase-8 and caspase-9. Sodium nitrite resulted in significant reduction in serum testosterone concentration and elevation in testis weight and Gonado-Somatic Index. We found significant reduction in testicular tissues levels of IL-4 and IL-10 associated with elevated levels of TNF-α, IL-1β, IL-6, caspase-3, caspase-8 and caspase-9. In conclusion, chronic oral sodium nitrite induced changes in the weight of rat testis accompanied by elevation in the testicular tissue level of oxidative stress markers and inflammatory cytokines. TQ attenuated sodium nitrite-induced testicular tissue damage through blocking oxidative stress, restoration of normal inflammatory cytokines balance and blocking of apoptosis.

  17. Inhibition of nitrite-induced toxicity in channel catfish by calcium chloride and sodium chloride

    Science.gov (United States)

    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).

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

    Science.gov (United States)

    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.

  19. Haematological and ion regulatory effects of nitrite in the air-breathing snakehead fish Channa striata.

    Science.gov (United States)

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

    2012-08-15

    The tolerance and effects of nitrite on ion balance and haematology were investigated in the striped snakehead, Channa striata Bloch 1793, which is an air-breathing fish with reduced gills of importance for aquaculture in South East Asia. C. striata was nitrite tolerant with a 96 h LC50 of 4.7 mM. Effects of sub-lethal exposures to nitrite (0mM, 1.4mM, and 3.0mM) were determined during a 7-day exposure period. Plasma nitrite increased, but the internal concentration remained well below ambient levels. Extracellular nitrate rose by several mM, indicating that a large proportion of the nitrite taken up was converted to nitrate. Nitrite reacted with erythrocyte haemoglobin (Hb) causing methaemoglobin (metHb) to increase to 30% and nitrosylhaemoglobin (HbNO) to increase to 10% of total Hb. Both metHb and HbNO stabilised after 4 days, and functional Hb levels accordingly never fell below 60% of total Hb. Haematocrit and total Hb were unaffected by nitrite. Although the effects of nitrite exposure seemed minor in terms of plasma nitrite and metHb increases, ion balance was strongly affected. In the high exposure group, total osmolality decreased from 320 mOsm to 260 mOsm, and plasma sodium from 150 mM to 120 mM, while plasma chloride fell from 105 mM to 60mM and plasma bicarbonate rose from 12 mM in controls to 20mM in exposed fish. The extreme changes in ion balance in C. striata are different from the response reported in other fish, and further studies are needed to investigate the mechanism behind the observed changes in regulation.

  20. Nitric oxide generation from heme/copper assembly mediated nitrite reductase activity.

    Science.gov (United States)

    Hematian, Shabnam; Siegler, Maxime A; Karlin, Kenneth D

    2014-06-01

    Nitric oxide (NO) as a cellular signaling molecule and vasodilator regulates a range of physiological and pathological processes. Nitrite (NO2 (-)) is recycled in vivo to generate nitric oxide, particularly in physiologic hypoxia and ischemia. The cytochrome c oxidase binuclear heme a 3/CuB active site is one entity known to be responsible for conversion of cellular nitrite to nitric oxide. We recently reported that a partially reduced heme/copper assembly reduces nitrite ion, producing nitric oxide; the heme serves as the reductant and the cupric ion provides a Lewis acid interaction with nitrite, facilitating nitrite (N-O) bond cleavage (Hematian et al., J. Am. Chem. Soc. 134:18912-18915, 2012). To further investigate this nitrite reductase chemistry, copper(II)-nitrito complexes with tridentate and tetradentate ligands were used in this study, where either O,O'-bidentate or O-unidentate modes of nitrite binding to the cupric center are present. To study the role of the reducing ability of the ferrous heme center, two different tetraarylporphyrinate-iron(II) complexes, one with electron-donating para-methoxy peripheral substituents and the other with electron-withdrawing 2,6-difluorophenyl substituents, were used. The results show that differing modes of nitrite coordination to the copper(II) ion lead to differing kinetic behavior. Here, also, the ferrous heme is in all cases the source of the reducing equivalent required to convert nitrite to nitric oxide, but the reduction ability of the heme center does not play a key role in the observed overall reaction rate. On the basis of our observations, reaction mechanisms are proposed and discussed in terms of heme/copper heterobinuclear structures.

  1. Transpulmonary plasma ET-1 and nitrite differences in high altitude pulmonary hypertension.

    Science.gov (United States)

    Berger, Marc M; Dehnert, Christoph; Bailey, Damian M; Luks, Andrew M; Menold, Elmar; Castell, Christian; Schendler, Guido; Faoro, Vitalie; Mairbäurl, Heimo; Bärtsch, Peter; Swenson, Erik R

    2009-01-01

    Berger, Marc M., Christoph Dehnert, Damian M. Bailey, Andrew M. Luks, Elmar Menold, Christian Castell, Guido Schendler, Vitalie Faoro, Heimo Mairbäurl, Peter Bärtsch, and Eric R. Swenson. Transpulmonary plasma ET-1 and nitrite differences in high altitude pulmonary hypertension. High Alt. Med. Biol. 10:17-24, 2009.- Thirty-four mountaineers were studied at low (110 m) and high altitude (4559 m) to evaluate if increased pulmonary artery systolic pressure (PASP) at high altitude is associated with increased pulmonary endothelin-1 (ET-1) availability and alterations in nitrite metabolism across the lung. Blood samples were obtained using central venous and radial artery catheters for plasma ET-1 and nitrite. Pulmonary blood flow was measured by inert gas rebreathing to calculate transpulmonary exchange of plasma ET-1 and nitrite, and PASP was assessed by transthoracic Doppler echocardiography. After ascent to high altitude, PASP increased from 23 +/- 4 to 39 +/- 10 mmHg. Arterial and central venous plasma ET-1 increased, while plasma nitrite did not change significantly. At low altitude there was a transpulmonary loss of plasma ET-1, but a transpulmonary gain at high altitude. In contrast was a transpulmonary gain of plasma nitrite at low altitude and a transpulmonary loss at high altitude. PASP positively correlated with a transpulmonary gain of plasma ET-1 and negatively correlated with a transpulmonary loss of plasma nitrite. These results suggest that a transpulmonary gain of plasma ET- 1 is associated with higher PASP at high altitude. Transpulmonary loss of plasma nitrite indicates either less pulmonary nitric oxide (NO) production, which contributes to higher PASP, or increased NO bioavailability arising from nitrite reduction, which may oppose ET-1-mediated vasoconstriction.

  2. Solubilities of sodium nitrate, sodium nitrite, and sodium aluminate in simulated nuclear waste

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, D.A.; Herting, D.L.

    1984-09-01

    Solubilities were determined for sodium nitrate, sodium nitrite, and sodium aluminate in synthetic nuclear waste liquor. Solubilities were determined as a function of temperature and solution composition (concentrations of sodium hydroxide, sodium nitrate, sodium nitrite, and sodium aluminate). Temperature had the greatest effect on the solubilities of sodium nitrate and sodium nitrite and a somewhat lesser effect on sodium aluminate solubility. Hydroxide had a great effect on the solubilities of all three salts. Other solution components had minor effects. 2 references, 8 figures, 11 tables.

  3. Stress Corrosion Cracking of an Austenitic Stainless Steel in Nitrite-Containing Chloride Solutions

    Directory of Open Access Journals (Sweden)

    R. K. Singh Raman

    2014-12-01

    Full Text Available This article describes the susceptibility of 316L stainless steel to stress corrosion cracking (SCC in a nitrite-containing chloride solution. Slow strain rate testing (SSRT in 30 wt. % MgCl2 solution established SCC susceptibility, as evidenced by post-SSRT fractography. Addition of nitrite to the chloride solution, which is reported to have inhibitive influence on corrosion of stainless steels, was found to increase SCC susceptibility. The susceptibility was also found to increase with nitrite concentration. This behaviour is explained on the basis of the passivation and pitting characteristics of 316L steel in chloride solution.

  4. A carbon nanotube/polyvanillin composite film as an electrocatalyst for the electrochemical oxidation of nitrite and its application as a nitrite sensor

    Energy Technology Data Exchange (ETDEWEB)

    Zheng Dongyun [College of Chemistry and Molecular Science, Wuhan University, Wuhan 430072 (China); State Key Laboratory of Transducer Technology, Chinese Academy of Sciences (China); Hu Chengguo [College of Chemistry and Molecular Science, Wuhan University, Wuhan 430072 (China); State Key Laboratory of Transducer Technology, Chinese Academy of Sciences (China)], E-mail: cghu@whu.edu.cn; Peng Yanfen [College of Chemistry and Molecular Science, Wuhan University, Wuhan 430072 (China); State Key Laboratory of Transducer Technology, Chinese Academy of Sciences (China); Hu Shengshui [College of Chemistry and Molecular Science, Wuhan University, Wuhan 430072 (China); State Key Laboratory of Transducer Technology, Chinese Academy of Sciences (China)], E-mail: sshu@whu.edu.cn

    2009-08-30

    We report a simple method for the stable dispersion of multi-walled carbon nanotubes (MWNTs) in water by vanillin and controllable surface addition onto carbon fiber microelectrodes (CFE) via electropolymerization. We have characterized these polyvanillin-carbon nanotube (PVN-MWNT) composite films with techniques including scanning electron microscopy (SEM), infrared spectroscopy (IR) and voltammetry. These investigations showed that the films have a uniform porous nanostructure with a large surface area. This PVN-MWNT composite-modified CFE (PVN-MWNT/CFE) exhibited a sensitive response to the electrochemical oxidation of nitrite. Under optimal working conditions, the oxidation peak current of nitrite linearly increased with its concentration in the range of 0.2 {mu}M-3.1 mM, with the system exhibiting a lower detection limit of 50 nM (S/N = 3). We successfully applied the PVN-MWNT/CFE system to the determination of nitrite from lake water. The efficient recovery of nitrite indicated that this electrode was able to detect nitrite in real samples.

  5. Effect of Initial nitrite concentration on growth of spirulina platensis; Supirurina no zoshoku ni oyobosu ashosan ion shonodo no eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Ohira, Y.; Obata, E.; Kuga, Y.; Ando, K. [Muroran Inst. of Tech., Hokkaido (Japan). Dept. of Applied Chemistry; Yamada, S.

    2000-09-10

    The effect of the initial nitrite concentration on the growth of S. platensis was experimentally investigated using the medium added to the sodium nitrite of 0.0-1.6 kg{center_dot}m{sup -3}. When the initial nitrite concentration is smaller than 0.8 kg{center_dot}m{sup -3}, the growth rate is greater than that without nitrite. The specific growth rate had the maximum value and is approximately 1.3 times that of a standard medium when the range of the initial nitrite concentration is 0.3-0.4 kg{center_dot}m{sup -3}. When the initial nitrite concentration is greater than 0.8 kg{center_dot}m{sup -3}, the growth rate was smaller than that of a standard medium due to nitrite inhibition. (author)

  6. The Effect of Influent Characteristics and Operational Conditions over the Performance and Microbial Community Structure of Partial Nitritation Reactors

    Directory of Open Access Journals (Sweden)

    Alejandro Rodriguez-Sanchez

    2014-06-01

    Full Text Available Nitrogen is a main contaminant of wastewater worldwide. Novel processes for nitrogen removal have been developed over the last several decades. One of these is the partial nitritation process. This process includes the oxidation of ammonium to nitrite without the generation of nitrate. The partial nitritation process has several advantages over traditional nitrification-denitrification processes for nitrogen removal from wastewaters. In addition, partial nitritation is required for anammox elimination of nitrogen from wastewater. Partial nitritation is affected by operational conditions and substances present in the influent, such as quinolone antibiotics. In this review, the impact that several operational conditions, such as temperature, pH, dissolved oxygen concentration, hydraulic retention time and solids retention time, have over the partial nitritation process is covered. The effect of quinolone antibiotics and other emerging contaminants are discussed. Finally, future perspectives for the partial nitritation process are commented upon.

  7. Determination of low level methyl tert-butyl ether, ethyl tert-butyl ether and methyl tert-amyl ether in human urine by HS-SPME gas chromatography/mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Scibetta, Licia [Department of Occupational and Environmental Medicine, University of Milano and Fondazione IRCCS Ospedale Maggiore Policlinico, Mangiagalli e Regina Elena, Via S. Barnaba, 8-20122 Milan (Italy); Campo, Laura [Department of Occupational and Environmental Medicine, University of Milano and Fondazione IRCCS Ospedale Maggiore Policlinico, Mangiagalli e Regina Elena, Via S. Barnaba, 8-20122 Milan (Italy); Mercadante, Rosa [Department of Occupational and Environmental Medicine, University of Milano and Fondazione IRCCS Ospedale Maggiore Policlinico, Mangiagalli e Regina Elena, Via S. Barnaba, 8-20122 Milan (Italy); Foa, Vito [Department of Occupational and Environmental Medicine, University of Milano and Fondazione IRCCS Ospedale Maggiore Policlinico, Mangiagalli e Regina Elena, Via S. Barnaba, 8-20122 Milan (Italy); Fustinoni, Silvia [Department of Occupational and Environmental Medicine, University of Milano and Fondazione IRCCS Ospedale Maggiore Policlinico, Mangiagalli e Regina Elena, Via S. Barnaba, 8-20122 Milan (Italy)]. E-mail: silvia.fustinoni@unimi.it

    2007-01-02

    Methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE) and tert-amyl methyl ether (TAME) are oxygenated compounds added to gasoline to enhance octane rating and to improve combustion. They may be found as pollutants of living and working environments. In this work a robotized method for the quantification of low level MTBE, ETBE and TAME in human urine was developed and validated. The analytes were sampled in the headspace of urine by SPME in the presence of MTBE-d12 as internal standard. Different fibers were compared for their linearity and extraction efficiency: carboxen/polydimethylsiloxane, polydimethylsiloxane/divinylbenzene, and polydimethylsiloxane. The first, although highly efficient, was discarded due to deviation of linearity for competitive displacement, and the polydimethylsiloxane/divinylbenzene fiber was chosen instead. The analysis was performed by GC/MS operating in the electron impact mode. The method is very specific, with range of linearity 30-4600 ng L{sup -1}, within- and between-run precision, as coefficient of variation, <22 and <16%, accuracy within 20% the theoretical level, and limit of detection of 6 ng L{sup -1} for all the analytes. The influence of the matrix on the quantification of these ethers was evaluated analysing the specimens of seven traffic policemen exposed to autovehicular emissions: using the calibration curve and the method of standard additions comparable levels of MTBE (68-528 ng L{sup -1}), ETBE (<6 ng L{sup -1}), and TAME (<6 ng L{sup -1}) were obtained.

  8. Bacterial degradation of tert-amyl alcohol proceeds via hemiterpene 2-methyl-3-buten-2-ol by employing the tertiary alcohol desaturase function of the Rieske nonheme mononuclear iron oxygenase MdpJ.

    Science.gov (United States)

    Schuster, Judith; Schäfer, Franziska; Hübler, Nora; Brandt, Anne; Rosell, Mònica; Härtig, Claus; Harms, Hauke; Müller, Roland H; Rohwerder, Thore

    2012-03-01

    Tertiary alcohols, such as tert-butyl alcohol (TBA) and tert-amyl alcohol (TAA) and higher homologues, are only slowly degraded microbially. The conversion of TBA seems to proceed via hydroxylation to 2-methylpropan-1,2-diol, which is further oxidized to 2-hydroxyisobutyric acid. By analogy, a branched pathway is expected for the degradation of TAA, as this molecule possesses several potential hydroxylation sites. In Aquincola tertiaricarbonis L108 and Methylibium petroleiphilum PM1, a likely candidate catalyst for hydroxylations is the putative tertiary alcohol monooxygenase MdpJ. However, by comparing metabolite accumulations in wild-type strains of L108 and PM1 and in two mdpJ knockout mutants of strain L108, we could clearly show that MdpJ is not hydroxylating TAA to diols but functions as a desaturase, resulting in the formation of the hemiterpene 2-methyl-3-buten-2-ol. The latter is further processed via the hemiterpenes prenol, prenal, and 3-methylcrotonic acid. Likewise, 3-methyl-3-pentanol is degraded via 3-methyl-1-penten-3-ol. Wild-type strain L108 and mdpJ knockout mutants formed isoamylene and isoprene from TAA and 2-methyl-3-buten-2-ol, respectively. It is likely that this dehydratase activity is catalyzed by a not-yet-characterized enzyme postulated for the isomerization of 2-methyl-3-buten-2-ol and prenol. The vitamin requirements of strain L108 growing on TAA and the occurrence of 3-methylcrotonic acid as a metabolite indicate that TAA and hemiterpene degradation are linked with the catabolic route of the amino acid leucine, including an involvement of the biotin-dependent 3-methylcrotonyl coenzyme A (3-methylcrotonyl-CoA) carboxylase LiuBD. Evolutionary aspects of favored desaturase versus hydroxylation pathways for TAA conversion and the possible role of MdpJ in the degradation of higher tertiary alcohols are discussed.

  9. Nitrite Biosensing via Selective Enzymes—A Long but Promising Route

    Directory of Open Access Journals (Sweden)

    M. Gabriela Almeida

    2010-12-01

    Full Text Available 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.

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

    DEFF Research Database (Denmark)

    Koch, Hanna; Lücker, Sebastian; Albertsen, Mads

    2015-01-01

    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...

  11. Harvesting biohydrogen from cellobiose from sulfide or nitrite-containing wastewaters using Clostridium sp. R1.

    Science.gov (United States)

    Ho, Kuo-Ling; Lee, Duu-Jong

    2011-09-01

    Harvesting biohydrogen from inhibiting wastewaters is of practical interest since the toxicity of compounds in a wastewater stream commonly prevents the bioenergy content being recovered. The isolated Clostridium sp. R1 is utilized to degrade cellobiose in sulfide or nitrite-containing medium for biohydrogen production. The strain can effectively degrade cellobiose free of severe inhibitory effects at up to 200 mgl(-1) sulfide or to 5 mgl(-1) nitrite, yielding hydrogen at >2.0 mol H2 mol(-1) cellobiose. Principal metabolites of cellobiose fermentation are acetate and butyrate, with the concentration of the former increases with increasing sulfide and nitrite concentrations. The isolated strain can yield hydrogen from cellobiose in sulfide-laden wastewaters. However, the present of nitrite significantly limit the efficiency of the biohydrogen harvesting process.

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

    OpenAIRE

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

    2015-01-01

    Nitrification, the sequential aerobic oxidation of ammonia via nitrite to nitrate, is a key process of the biogeochemical nitrogen cycle and catalyzed by two aerobic microbial guilds (nitrifiers): ammonia oxidizers and nitrite-oxidizing bacteria (NOB). NOB are generally considered as metabolically restricted and dependent on ammonia oxidizers. Here, we report that, surprisingly, key NOB of many ecosystems (Nitrospira) convert urea, an important ammonia source in nature, to ammonia and CO2. Th...

  13. Conversion of nitrite to nitric oxide at zinc via S-nitrosothiols.

    Science.gov (United States)

    Cardenas, Allan Jay P; Abelman, Rebecca; Warren, Timothy H

    2014-01-07

    Nitrite is an important reservoir of nitric oxide activity in the plasma and cells. Using a biomimetic model, we demonstrate the conversion of zinc-bound nitrite in the tris(pyrazolyl)borate complex (iPr2)TpZn(NO2) to the corresponding S-nitrosothiol RSNO and zinc thiolate (iPr2)TpZn-SR via reaction with thiols H-SR. Decomposition of the S-nitrosothiol formed releases nitric oxide gas.

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

    Science.gov (United States)

    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.

  15. Analysis of responses to glyceryl trinitrate and sodium nitrite in the intact chest rat.

    Science.gov (United States)

    Nossaman, Bobby D; Pankey, Edward A; Badejo, Adeleke R; Casey, David B; Uppu, Satvika; Murthy, Subramanyam N; Kadowitz, Philip J

    2012-05-15

    Responses to glyceryl trinitrate/nitroglycerin (GTN), S-nitrosoglutathione (GSNO), and sodium nitrite were compared in the intact chest rat. The iv injections of GTN, sodium nitrite, and GSNO produced dose-dependent decreases in pulmonary and systemic arterial pressures. In as much as cardiac output was not reduced, the decreases in pulmonary and systemic arterial pressures indicate that GTN, sodium nitrite, and GSNO have significant vasodilator activity in the pulmonary and systemic vascular beds in the rat. Responses to GTN were attenuated by cyanamide, but not allopurinol, whereas responses to nitrite formed by the metabolism of GTN were attenuated by allopurinol and cyanamide. The results with allopurinol and cyanamide suggest that only mitochondrial aldehyde dehydrogenase is involved in the bioactivation of GTN, sodium nitrite, and GSNO, whereas both pathways are involved in the bioactivation of nitrite anion in the intact rat. The comparison of vasodilator activity indicates that GSNO and GTN are more than 1000-fold more potent than sodium nitrite in decreasing pulmonary and systemic arterial pressures in the rat. Following administration of 1H-[1,2,4]-oxadizaolo[4,3-]quinoxaline-1-one (ODQ), responses to GTN were significantly attenuated, indicating that responses are mediated by the activation of soluble guanylyl cyclase. These data suggest that the reduction of nitrite to nitric oxide formed from the metabolism of GTN, cannot account for the vasodilator activity of GTN in the intact rat and that another mechanism; perhaps the formation of an S-NO, may mediate the vasodilator response to GTN in this species.

  16. Effect of Nitrite/Nitrate concentrations on Corrosivity of Washed Precipitate

    Energy Technology Data Exchange (ETDEWEB)

    Congdon, J.W.

    2001-03-28

    Cyclic polarization scans were performed using A-537 carbon steel in simulated washed precipitate solutions of various nitrite and nitrate concentrations. The results of this study indicate that nitrate is an aggressive anion in washed precipitate. Furthermore, a quantitative linear log-log relationship between the minimum effective nitrite concentration and the nitrate concentration was established for washed precipitate with other ions at their average compositions.

  17. Nitrite attenuated peroxynitrite and hypochlorite generation in activated neutrophils.

    Science.gov (United States)

    Ren, Xiaoming; Ding, Yun; Lu, Naihao

    2016-03-15

    Oxidative stress is usually considered as an important factor to the pathogenesis of various diseases. Peroxynitrite (ONOO(-)) and hypochlorite (OCl(-)) are formed in immune cells as a part of the innate host defense system, but excessive reactive oxygen species generation can cause progressive inflammation and tissue damage. It has been proven that through mediating nitric oxide (NO) homeostasis, inorganic nitrite (NO2(-)) shows organ-protective effects on oxidative stress and inflammation. However, the effects of NO2(-) on the function of immune cells were still not clear. The potential role of NO2(-) in modulating ONOO(-) and OCl(-) generation in neutrophil cells was investigated in this study. As an immune cell activator, lipopolysaccharide (LPS) increased both ONOO(-) and OCl(-) production in neutrophils, which was significantly attenuated by NO2(-). NO2(-) reduced superoxide (O2(·-)) generation via a NO-dependent mechanism and increased NO formation in activated neutrophils, suggesting a crucial role of O2(·-) in NO2(-)-mediated reduction of ONOO(-). Moreover, the reduced effect of NO2(-) on OCl(-) production was attributed to that NO2(-) reduced H2O2 production in activated neutrophils without influencing the release of myeloperoxidase (MPO), thus limiting OCl(-) production by MPO/H2O2 system. Therefore, NO2(-) attenuates ONOO(-) and OCl(-) formation in activated neutrophils, opening a new direction to modulate the inflammatory response.

  18. Performance and microbial ecology of a nitritation sequencing batch reactor treating high-strength ammonia wastewater

    Science.gov (United States)

    Chen, Wenjing; Dai, Xiaohu; Cao, Dawen; Wang, Sha; Hu, Xiaona; Liu, Wenru; Yang, Dianhai

    2016-01-01

    The partial nitrification (PN) performance and the microbial community variations were evaluated in a sequencing batch reactor (SBR) for 172 days, with the stepwise elevation of ammonium concentration. Free ammonia (FA) and low dissolved oxygen inhibition of nitrite-oxidized bacteria (NOB) were used to achieve nitritation in the SBR. During the 172 days operation, the nitrogen loading rate of the SBR was finally raised to 3.6 kg N/m3/d corresponding the influent ammonium of 1500 mg/L, with the ammonium removal efficiency and nitrite accumulation rate were 94.12% and 83.54%, respectively, indicating that the syntrophic inhibition of FA and low dissolved oxygen contributed substantially to the stable nitrite accumulation. The results of the 16S rRNA high-throughput sequencing revealed that Nitrospira, the only nitrite-oxidizing bacteria in the system, were successively inhibited and eliminated, and the SBR reactor was dominated finally by Nitrosomonas, the ammonium-oxidizing bacteria, which had a relative abundance of 83%, indicating that the Nitrosomonas played the primary roles on the establishment and maintaining of nitritation. Followed by Nitrosomonas, Anaerolineae (7.02%) and Saprospira (1.86%) were the other mainly genera in the biomass. PMID:27762325

  19. Energetic Consequences of nitrite stress in Desulfovibrio vulgarisHildenborough, inferred from global transcriptional analysis

    Energy Technology Data Exchange (ETDEWEB)

    He, Qiang; Huang, Katherine H.; He, Zhili; Alm, Eric J.; Fields,Matthew W.; Hazen, Terry C.; Arkin, Adam P.; Wall, Judy D.; Zhou, Jizhong

    2005-11-03

    Many of the proteins that are candidates for bioenergetic pathways involved with sulfate respiration in Desulfovibrio spp. have been studied, but complete pathways and overall cell physiology remain to be resolved for many environmentally relevant conditions. In order to understand the metabolism of these microorganisms under adverse environmental conditions for improved bioremediation efforts, Desulfovibrio vulgaris Hildenborough was used as a model organism to study stress response to nitrite, an important intermediate in the nitrogen cycle. Previous physiological studies demonstrated that growth was inhibited by nitrite and that nitrite reduction was observed to be the primary mechanism of detoxification. Global transcriptional profiling with whole-genome microarrays revealed coordinated cascades of responses to nitrite in pathways of energy metabolism, nitrogen metabolism, oxidative stress response, and iron homeostasis. In agreement with previous observations, nitrite-stressed cells showed a decrease in the expression of genes encoding sulfate reduction functions in addition to respiratory oxidative phosphorylation and ATP synthase activity. Consequently, the stressed cells had decreased expression of the genes encoding ATP-dependent amino acid transporters and proteins involved in translation. Other genes up-regulated in response to nitrite include the genes in the Fur regulon, which is suggested to be involved in iron homeostasis, and genes in the Per regulon, which is predicted to be responsible for oxidative stress response.

  20. Production of cured meat color in nitrite-free Harbin red sausage by Lactobacillus fermentum fermentation.

    Science.gov (United States)

    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.

  1. Optimization of fermentation media for nitrite oxidizing bacteria using sequential statistical design.

    Science.gov (United States)

    Ren, Jie; Lin, Wei-Tie; Shen, Yan-Jing; Wang, Ju-Fang; Luo, Xiao-Chun; Xie, Ming-Quan

    2008-11-01

    The sequential statistical experimental design (Plackett-Burman, factorial, response surface and steepest ascent experiment) was applied to optimize the culture medium of nitrite oxidizing bacteria for improving the nitrite oxidizing rate. Estimated optimum medium composition of the nitrite oxidizing rate was as follows: NaHCO3, 1.86gl(-1); NaNO2, 2.04gl(-1); Na2CO3, 0.2gl(-1); NaCl, 0.2gl(-1); KH2PO4, 0.1gl(-1); MgSO4 x7H2O, 0.1gl(-1); and FeSO4 x 7H2O, 0.01gl(-1). The nitrite oxidizing rate was increased by 48.0% and reached a maximum at 859.5+/-8.4mgNO2-N/gMLSS.d as compared to 580.7+/-25.8mgNO2-N/gMLSS x d. In the field trial, 50L of nitrite oxidizing bacteria concentrate (1.99gVSS/L) with 850mgNO2-N/gMLSS x d were added to 0.6ha of the aquaculture water. Nitrite level in all treated ponds remained very low compared to the steady increase observed in all of the control ponds during 7 days.

  2. Consistent antioxidant and antihypertensive effects of oral sodium nitrite in DOCA-salt hypertension

    Directory of Open Access Journals (Sweden)

    Jefferson H. Amaral

    2015-08-01

    Full Text Available Hypertension is a common disease that includes oxidative stress as a major feature, and oxidative stress impairs physiological nitric oxide (NO activity promoting cardiovascular pathophysiological mechanisms. While inorganic nitrite and nitrate are now recognized as relevant sources of NO after their bioactivation by enzymatic and non-enzymatic pathways, thus lowering blood pressure, mounting evidence suggests that sodium nitrite also exerts antioxidant effects. Here we show for the first time that sodium nitrite exerts consistent systemic and vascular antioxidant and antihypertensive effects in the deoxycorticosterone-salt (DOCA-salt hypertension model. This is particularly important because increased oxidative stress plays a major role in the DOCA-salt hypertension model, which is less dependent on activation of the renin-angiotensin system than other hypertension models. Indeed, antihypertensive effects of oral nitrite were associated with increased plasma nitrite and nitrate concentrations, and completely blunted hypertension-induced increases in plasma 8-isoprostane and lipid peroxide levels, in vascular reactive oxygen species, in vascular NADPH oxidase activity, and in vascular xanthine oxidoreductase activity. Together, these findings provide evidence that the oral administration of sodium nitrite consistently decreases the blood pressure in association with major antioxidant effects in experimental hypertension.

  3. Numerical modeling of nitrogen removal processes in biofilters with simultaneous nitritation and anammox.

    Science.gov (United States)

    Shi, Shun; Tao, Wendong

    2013-01-01

    This study developed a simple numerical model for nitrogen removal in biofilters, which was designed to enhance simultaneous nitritation and anaerobic ammonium oxidation (anammox). It is the first attempt to simulate anammox together with two-step nitrification in natural treatment systems, which may have different kinetic parameters and temperature effects from conventional bioreactors. Prediction accuracy was improved by adjusting kinetic coefficients over the startup period of the biofilters. The maximum rates of nitritation and nitrite oxidation increased linearly over time during the startup period. Simulations confirmed successful enhancement of simultaneous nitritation and anammox (SNA) in the biofilters, with anammox contributing 35% of ammonium removal. Effluent ammonium concentration was affected by influent ammonium concentration and the maximum nitritation rate, and was insensitive to the maximum nitrite oxidation rate and anammox substrate factor. Ammonium removal via SNA was likely limited by biomass of aerobic ammonia oxidizing bacteria in the biofilters. The developed model is a promising tool for studying the dynamics of nitrogen removal processes including SNA in natural treatment systems.

  4. Therapeutic effects of inorganic nitrate and nitrite in cardiovascular and metabolic diseases.

    Science.gov (United States)

    Omar, S A; Webb, A J; Lundberg, J O; Weitzberg, E

    2016-04-01

    Nitric oxide (NO) is generated endogenously by NO synthases to regulate a number of physiological processes including cardiovascular and metabolic functions. A decrease in the production and bioavailability of NO is a hallmark of many major chronic diseases including hypertension, ischaemia-reperfusion injury, atherosclerosis and diabetes. This NO deficiency is mainly caused by dysfunctional NO synthases and increased scavenging of NO by the formation of reactive oxygen species. Inorganic nitrate and nitrite are emerging as substrates for in vivo NO synthase-independent formation of NO bioactivity. These anions are oxidation products of endogenous NO generation and are also present in the diet, with green leafy vegetables having a high nitrate content. The effects of nitrate and nitrite are diverse and include vasodilatation, improved endothelial function, enhanced mitochondrial efficiency and reduced generation of reactive oxygen species. Administration of nitrate or nitrite in animal models of cardiovascular disease shows promising results, and clinical trials are currently ongoing to investigate the therapeutic potential of nitrate and nitrite in hypertension, pulmonary hypertension, peripheral artery disease and myocardial infarction. In addition, the nutritional aspects of the nitrate-nitrite-NO pathway are interesting as diets suggested to protect against cardiovascular disease, such as the Mediterranean diet, are especially high in nitrate. Here, we discuss the potential therapeutic opportunities for nitrate and nitrite in prevention and treatment of cardiovascular and metabolic diseases.

  5. Spectrophotometric determination of nitrite in soil and water using cefixime and central composite design

    Science.gov (United States)

    Shariati-Rad, Masoud; Irandoust, Mohsen; Mohammadi, Shabnam

    2015-10-01

    The present paper seeks to develop a simple method for the spectrophotometric determination of nitrite in soil and water samples and also measure optimum reaction conditions along with other analytical parameters. The method is based on the diazotization-coupling reaction of nitrite with cefixime and 1-naphthylamine in an acidic solution (Griess reaction). The final product that is an azo dye has an orange color with maximum absorption at 360 nm which Beer's Law is obeyed over the concentration range 0.02-15.00 mg L-1 of nitrite. Optimal conditions of the variables affecting the reaction were obtained by central composite design (CCD). A detection limit of 4.3 × 10-3 mg L-1 was obtained for determination of nitrite by the proposed method. The proposed method was successfully applied to determine nitrite in soil and water samples. The molar absorptivity of the product of the reaction and RSD in determination of nitrite in real samples are 4.1 × 103 (L mol-1 cm-1) and lower than 10%, respectively.

  6. A Family Clustered Nitrite Intoxication Investigation in Gaoxin District, Suzhou, China, 2013.

    Directory of Open Access Journals (Sweden)

    Ruiping Wang

    2013-12-01

    Full Text Available In April, 2013, a Suzhou Hospital reported a nitrite intoxication patient in coma as well as 2 family members with the similar symptom 5 days ahead. We investigated the event to identify the cause, source and possible pollution ways of the contamination.We defined case as any person living in YSHY community who has cyanosis and with at least one of the following symptoms: dizziness, headache, fatigue, tachycardia, drowsiness, nausea, vomiting, abdominal pain or diar-rhea during April 15 to April 25, 2013. We searched for case by interviewing community residents and reviewing clinics' medical records; information was then retrospectively collected on the patient's food history, cooking procedures and food sources.We identified 3 nitrite intoxication cases, 1 male and 2 female from a family. The interval time between dinner and onset was < 1 hour. Retrospective survey showed 'sugar stir and mix asparagus' on April 17 and 'scrambled asparagus' on April 21 were suspected foods. Both suspected dishes had 'sugar' added, sourced from a clean-up of a neighboring rental house. Nitrite was detected in a vomitus sample, the 'sugar' and two leftover food samples.This family clustered nitrite intoxication was induced by using unidentified nitrite as sugar to cook dishes. We recommend sodium nitrite should be dyed with bright colors to avoid mistaking it for plain salt or sugar, health departments strengthen food hygiene propaganda to improve people's recognition of food safety, and to alert them the dangerous of eating unidentified or unknown source food.

  7. Effect of lycopene on serum nitrite-nitrate levels in diabetic rats

    Directory of Open Access Journals (Sweden)

    Sevim Ç Yegin

    2015-01-01

    Full Text Available The effect of lycopene on serum nitrate-nitrite levels was investigated in diabetic rats. In this investigation, 28 Wistar rats were divided into 4 groups, each of seven rats. These groups were control group, diabetes group, diabetes-lycopene group and lycopene group. The concentration of nitrite and nitrate was detected at high levels in diabetes group, diabetes-lycopene group and lycopene group as compared with the control group (P<0.05. Especially, the increase in the levels of nitrate in diabetes group and lycopene group was statistically significant when compared with diabetes-lycopene group and control group (P<0.05. In addition, we also determined the proportion of nitrite/nitrate for nitric oxide radical formation. Therefore, it is important to investigate the recovery and stability of nitrite and nitrate in samples. As a result of this study, it was observed that the amounts of nitrate and nitrite increased due to oxidative stress in diabetes and also application of antioxidant lycopene caused an increase in the amounts of nitrate and nitrite levels.

  8. Enhanced activity and selectivity of carbon nanofiber supported Pd catalysts for nitrite reduction.

    Science.gov (United States)

    Shuai, Danmeng; Choe, Jong Kwon; Shapley, John R; Werth, Charles J

    2012-03-06

    Pd-based catalyst treatment represents an emerging technology that shows promise to remove nitrate and nitrite from drinking water. In this work we use vapor-grown carbon nanofiber (CNF) supports in order to explore the effects of Pd nanoparticle size and interior versus exterior loading on nitrite reduction activity and selectivity (i.e., dinitrogen over ammonia production). Results show that nitrite reduction activity increases by 3.1-fold and selectivity decreases by 8.0-fold, with decreasing Pd nanoparticle size from 1.4 to 9.6 nm. Both activity and selectivity are not significantly influenced by Pd interior versus exterior CNF loading. Consequently, turnover frequencies (TOFs) among all CNF catalysts are similar, suggesting nitrite reduction is not sensitive to Pd location on CNFs nor Pd structure. CNF-based catalysts compare favorably to conventional Pd catalysts (i.e., Pd on activated carbon or alumina) with respect to nitrite reduction activity and selectivity, and they maintain activity over multiple reduction cycles. Hence, our results suggest new insights that an optimum Pd nanoparticle size on CNFs balances faster kinetics with lower ammonia production, that catalysts can be tailored at the nanoscale to improve catalytic performance for nitrite, and that CNFs hold promise as highly effective catalyst supports in drinking water treatment.

  9. Enhanced Activity and Selectivity of Carbon Nanofiber Supported Pd Catalysts for Nitrite Reduction

    KAUST Repository

    Shuai, Danmeng

    2012-03-06

    Pd-based catalyst treatment represents an emerging technology that shows promise to remove nitrate and nitrite from drinking water. In this work we use vapor-grown carbon nanofiber (CNF) supports in order to explore the effects of Pd nanoparticle size and interior versus exterior loading on nitrite reduction activity and selectivity (i.e., dinitrogen over ammonia production). Results show that nitrite reduction activity increases by 3.1-fold and selectivity decreases by 8.0-fold, with decreasing Pd nanoparticle size from 1.4 to 9.6 nm. Both activity and selectivity are not significantly influenced by Pd interior versus exterior CNF loading. Consequently, turnover frequencies (TOFs) among all CNF catalysts are similar, suggesting nitrite reduction is not sensitive to Pd location on CNFs nor Pd structure. CNF-based catalysts compare favorably to conventional Pd catalysts (i.e., Pd on activated carbon or alumina) with respect to nitrite reduction activity and selectivity, and they maintain activity over multiple reduction cycles. Hence, our results suggest new insights that an optimum Pd nanoparticle size on CNFs balances faster kinetics with lower ammonia production, that catalysts can be tailored at the nanoscale to improve catalytic performance for nitrite, and that CNFs hold promise as highly effective catalyst supports in drinking water treatment. © 2012 American Chemical Society.

  10. Use of gamma radiation on control of Clostridium botulinum in mortadella formulated with different nitrite levels

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  12. Nitrite consumption and associated isotope changes during a river flood event

    Science.gov (United States)

    Jacob, Juliane; Sanders, Tina; Dähnke, Kirstin

    2016-10-01

    In oceans, estuaries, and rivers, nitrification is an important nitrate source, and stable isotopes of nitrate are often used to investigate recycling processes (e.g. remineralisation, nitrification) in the water column. Nitrification is a two-step process, where ammonia is oxidised via nitrite to nitrate. Nitrite usually does not accumulate in natural environments, which makes it difficult to study the single isotope effect of ammonia oxidation or nitrite oxidation in natural systems. However, during an exceptional flood in the Elbe River in June 2013, we found a unique co-occurrence of ammonium, nitrite, and nitrate in the water column, returning towards normal summer conditions within 1 week. Over the course of the flood, we analysed the evolution of δ15N-NH4+ and δ15N-NO2- in the Elbe River. In concert with changes in suspended particulate matter (SPM) and δ15N SPM, as well as nitrate concentration, δ15N-NO3- and δ18O-NO3-, we calculated apparent isotope effects during net nitrite and nitrate consumption. During the flood event, > 97 % of total reactive nitrogen was nitrate, which was leached from the catchment area and appeared to be subject to assimilation. Ammonium and nitrite concentrations increased to 3.4 and 4.4 µmol L-1, respectively, likely due to remineralisation, nitrification, and denitrification in the water column. δ15N-NH4+ values increased up to 12 ‰, and δ15N-NO2- ranged from -8.0 to -14.2 ‰. Based on this, we calculated an apparent isotope effect 15ɛ of -10.0 ± 0.1 ‰ during net nitrite consumption, as well as an isotope effect 15ɛ of -4.0 ± 0.1 ‰ and 18ɛ of -5.3 ± 0.1 ‰ during net nitrate consumption. On the basis of the observed nitrite isotope changes, we evaluated different nitrite uptake processes in a simple box model. We found that a regime of combined riparian denitrification and 22 to 36 % nitrification fits best with measured data for the nitrite concentration decrease and isotope increase.

  13. Safety and feasibility of long-term intravenous sodium nitrite infusion in healthy volunteers.

    Directory of Open Access Journals (Sweden)

    Ryszard M Pluta

    Full Text Available BACKGROUND: Infusion of sodium nitrite could provide sustained therapeutic concentrations of nitric oxide (NO for the treatment of a variety of vascular disorders. The study was developed to determine the safety and feasibility of prolonged sodium nitrite infusion. METHODOLOGY: Healthy volunteers, aged 21 to 60 years old, were candidates for the study performed at the National Institutes of Health (NIH; protocol 05-N-0075 between July 2007 and August 2008. All subjects provided written consent to participate. Twelve subjects (5 males, 7 females; mean age, 38.8±9.2 years (range, 21-56 years were intravenously infused with increasing doses of sodium nitrite for 48 hours (starting dose at 4.2 µg/kg/hr; maximal dose of 533.8 µg/kg/hr. Clinical, physiologic and laboratory data before, during and after infusion were analyzed. FINDINGS: The maximal tolerated dose for intravenous infusion of sodium nitrite was 267 µg/kg/hr. Dose limiting toxicity occurred at 446 µg/kg/hr. Toxicity included a transient asymptomatic decrease of mean arterial blood pressure (more than 15 mmHg and/or an asymptomatic increase of methemoglobin level above 5%. Nitrite, nitrate, S-nitrosothiols concentrations in plasma and whole blood increased in all subjects and returned to preinfusion baseline values within 12 hours after cessation of the infusion. The mean half-life of nitrite estimated at maximal tolerated dose was 45.3 minutes for plasma and 51.4 minutes for whole blood. CONCLUSION: Sodium nitrite can be safely infused intravenously at defined concentrations for prolonged intervals. These results should be valuable for developing studies to investigate new NO treatment paradigms for a variety of clinical disorders, including cerebral vasospasm after subarachnoid hemorrhage, and ischemia of the heart, liver, kidney and brain, as well as organ transplants, blood-brain barrier modulation and pulmonary hypertension. CLINICAL TRIAL REGISTRATION INFORMATION: http

  14. The capacity of red blood cells to reduce nitrite determines nitric oxide generation under hypoxic conditions.

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    Marcel H Fens

    Full Text Available Nitric oxide (NO is a key regulator of vascular tone. Endothelial nitric oxide synthase (eNOS is responsible for NO generation under normoxic conditions. Under hypoxia however, eNOS is inactive and red blood cells (RBC provide an alternative NO generation pathway from nitrite to regulate hypoxic vasodilation. While nitrite reductase activity of hemoglobin is well acknowledged, little is known about generation of NO by intact RBC with physiological hemoglobin concentrations. We aimed to develop and apply a new approach to provide insights in the ability of RBC to convert nitrite into NO under hypoxic conditions. We established a novel experimental setup to evaluate nitrite uptake and the release of NO from RBC into the gas-phase under different conditions. NO measurements were similar to well-established clinical measurements of exhaled NO. Nitrite uptake was rapid, and after an initial lag phase NO release from RBC was constant in time under hypoxic conditions. The presence of oxygen greatly reduced NO release, whereas inhibition of eNOS and xanthine oxidoreductase (XOR did not affect NO release. A decreased pH increased NO release under hypoxic conditions. Hypothermia lowered NO release, while hyperthermia increased NO release. Whereas fetal hemoglobin did not alter NO release compared to adult hemoglobin, sickle RBC showed an increased ability to release NO. Under all conditions nitrite uptake by RBC was similar. This study shows that nitrite uptake into RBC is rapid and release of NO into the gas-phase continues for prolonged periods of time under hypoxic conditions. Changes in the RBC environment such as pH, temperature or hemoglobin type, affect NO release.

  15. The capacity of red blood cells to reduce nitrite determines nitric oxide generation under hypoxic conditions.

    Science.gov (United States)

    Fens, Marcel H; Larkin, Sandra K; Oronsky, Bryan; Scicinski, Jan; Morris, Claudia R; Kuypers, Frans A

    2014-01-01

    Nitric oxide (NO) is a key regulator of vascular tone. Endothelial nitric oxide synthase (eNOS) is responsible for NO generation under normoxic conditions. Under hypoxia however, eNOS is inactive and red blood cells (RBC) provide an alternative NO generation pathway from nitrite to regulate hypoxic vasodilation. While nitrite reductase activity of hemoglobin is well acknowledged, little is known about generation of NO by intact RBC with physiological hemoglobin concentrations. We aimed to develop and apply a new approach to provide insights in the ability of RBC to convert nitrite into NO under hypoxic conditions. We established a novel experimental setup to evaluate nitrite uptake and the release of NO from RBC into the gas-phase under different conditions. NO measurements were similar to well-established clinical measurements of exhaled NO. Nitrite uptake was rapid, and after an initial lag phase NO release from RBC was constant in time under hypoxic conditions. The presence of oxygen greatly reduced NO release, whereas inhibition of eNOS and xanthine oxidoreductase (XOR) did not affect NO release. A decreased pH increased NO release under hypoxic conditions. Hypothermia lowered NO release, while hyperthermia increased NO release. Whereas fetal hemoglobin did not alter NO release compared to adult hemoglobin, sickle RBC showed an increased ability to release NO. Under all conditions nitrite uptake by RBC was similar. This study shows that nitrite uptake into RBC is rapid and release of NO into the gas-phase continues for prolonged periods of time under hypoxic conditions. Changes in the RBC environment such as pH, temperature or hemoglobin type, affect NO release.

  16. Use of lysozyme from chicken egg white as a nitrite replacer in an Italian-type chicken sausage

    OpenAIRE

    Nalaka Sandun Abeyrathne; Ishani A.H.M.E.Herath; Jayasinghe J. M. Priyanath; Ahn, Dong U.

    2015-01-01

    Background: Sodium or potassium nitrite is widely used as a curing agent in sausages and other cured meat products. Nitrite has strong antimicrobial and antioxidant effects and generates cured meat color. Nitrite, however, can react with secondary or tertiary amines in meat to form carcinogenic, teratogenic and mutagenic N-nitroso compounds. Several findings have been suggested that high consumption of processed meat may increase the risk of cancer, and emphasized that dietary nitrosamines ar...

  17. Normoxic cyclic GMP-independent oxidative signaling by nitrite enhances airway epithelial cell proliferation and wound healing.

    Science.gov (United States)

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

    2012-05-15

    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 (NO(2)·) 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 1 μM). The effect of nitrite was blocked by the NO and NO(2)· 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 (H(2)O(2))/heme-peroxidase/NO(2)· signaling, the effects of nitrite were potentiated by superoxide dismutase (SOD) and low concentration H(2)O(2), 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

  18. Mitochondrial aldehyde dehydrogenase mediates vasodilator responses of glyceryl trinitrate and sodium nitrite in the pulmonary vascular bed of the rat.

    Science.gov (United States)

    Badejo, Adeleke M; Hodnette, Chris; Dhaliwal, Jasdeep S; Casey, David B; Pankey, Edward; Murthy, Subramanyam N; Nossaman, Bobby D; Hyman, Albert L; Kadowitz, Philip J

    2010-09-01

    It has been reported that mitochondrial aldehyde dehydrogenase (ALDH2) catalyzes the formation of glyceryl dinitrate and inorganic nitrite from glyceryl trinitrate (GTN), leading to an increase in cGMP and vasodilation in the coronary and systemic vascular beds. However, the role of nitric oxide (NO) formed from nitrite in mediating the response to GTN in the pulmonary vascular bed is uncertain. The purpose of the present study was to determine if nitrite plays a role in mediating vasodilator responses to GTN. In this study, intravenous injections of GTN and sodium nitrite decreased pulmonary and systemic arterial pressures and increased cardiac output. The decreases in pulmonary arterial pressure under baseline and elevated tone conditions and decreases in systemic arterial pressure in response to GTN and sodium nitrite were attenuated by cyanamide, an ALDH2 inhibitor, whereas responses to the NO donor, sodium nitroprusside (SNP), were not altered. The decreases in pulmonary and systemic arterial pressure in response to GTN and SNP were not altered by allopurinol, an inhibitor of xanthine oxidoreductase, whereas responses to sodium nitrite were attenuated. GTN was approximately 1,000-fold more potent than sodium nitrite in decreasing pulmonary and systemic arterial pressures. These results suggest that ALDH2 plays an important role in the bioactivation of GTN and nitrite in the pulmonary and systemic vascular beds and that the reduction of nitrite to vasoactive NO does not play an important role in mediating vasodilator responses to GTN in the intact chest rat.

  19. Study of Cobalt(III) Corrole as the Neutral Ionophore for Nitrite and Nitrate Detection via Polymeric Membrane Electrodes.

    Science.gov (United States)

    Yang, Si; Meyerhoff, Mark E

    2013-12-01

    Cobalt(III) 5, 10, 15-tris(4-tert-butylphenyl) corrole was synthesized and incorporated into plasticized poly(vinyl chloride) membranes and studied as a neutral carrier ionophore via potentiometry. This cobalt(III) complex has binding affinity to nitrite, and the resulting membrane electrode yields reversible and Nernstian response toward nitrite. Enhanced nitrite selectivity is observed over other anions, including lipophilic anions such as thiocyanate and perchlorate when an appropriate amount of lipophilic cationic sites are added to the membrane phase. Detection limit to nitrite is ca. 5 µM. Using tributylphosphate as the plasticizer with the cobalt(III) corrole species yields electrodes with enhanced nitrate selectivity.

  20. Long-term nitritation performance of ammonium-rich landfill leachate☆

    Institute of Scientific and Technical Information of China (English)

    Hongwei Sun; Xintao L; Yongzhen Peng; Shuying Wang; Juan Ma

    2015-01-01

    This study presents a biological system combined upflow anaerobic sludge bed (UASB) with sequencing batch reactor (SBR) to treat ammonium-rich landfill leachate. The start-up and operation of the nitritation at low temperatures were investigated. The synergetic interaction of free ammonia (FA) inhibition on nitrite-oxidizing bacteria (NOB) and process control was used to achieve nitritation in the SBR. It is demonstrated that nitritation was successful y started up in the SBR at low temperatures (14.0 °C–18.2 °C) by using FA inhibition coupled with process control, and then was maintained for 482 days at normal/low temperature. Although ammonia-oxidizing bacteria (AOB) and NOB co-existed within bacterial clusters in the SBR sludge, AOB were confirmed to be dominant nitrifying population species by scanning electron microscopic (SEM) observation and fluorescence in situ hybridization (FISH) analysis. This confirmation not only emphasized that cultivating the appropriate bacteria is essential for achieving stable nitritation performance, but it also revealed that NOB activity was strongly inhibited by FA rather than being eliminated altogether from the system.

  1. Practical Use of Nitrite and Basis for Dosage in the Manufacture of Meat Products

    DEFF Research Database (Denmark)

    Adler-Nissen, Jens; Ekgreen, Maria Helbo; Risum, Jørgen

    The use of nitrite (NaNO2) in the manufacture of salted (cured) meat products has a long tradition in the industry, dating back to the early twentieth century. Nitrite serves several technological purposes, primarily by the formation of a stable red colour in the meat and the inhibition of the gr......The use of nitrite (NaNO2) in the manufacture of salted (cured) meat products has a long tradition in the industry, dating back to the early twentieth century. Nitrite serves several technological purposes, primarily by the formation of a stable red colour in the meat and the inhibition...... number of experiments were conducted in Denmark in collaboration with the Danish meat manufacturing industry in 1981-1983. Wiltshire bacon and certain canned products largely for export were not investigated in this study, however. The adverse effects of nitrite can mainly be ascribed to the risk...... sausages. Arguments for maintaining this high level are lacking in the available literature, and on the basis of what can be deduced with respect to the manufacturing processes for these products, it is hard to conceive of substantial arguments for the high level of 180 mg/kg. For other heat...

  2. Effects of nitrite on phosphate uptake in anaerobic-oxic process

    Institute of Scientific and Technical Information of China (English)

    LI Jie; XIONG Biyong; ZHANG Shude; YANG Hong; ZHANG Jie

    2007-01-01

    An anaerobic-oxic(A/O)biological phosphorus removal reactor was operated to study the effect of nitrite on phosphate uptake.The phosphorus uptake profile was determined under different operating conditions.The results indicated that in addition to oxygen and nitrate(DPBNa,nitrate denitrifying phosphorus removal),to some extent,nitrite could also serve as an electron acceptor to achieve nitrite denitrifying phosphorus removal(DPBNi).The quantity and rate of phosphorus uptake of DPBNi,however,were evidently lower than that of DPBNa.The experiment results revealed that nitrite would bring toxic action to phosphate accumulating organisms(PAOs)when NO2- -N≥93]7 mg/L.The nitrite existing in the anoxic reactor made no difference to the quantity and rate of denitrifying phosphorus removal,but it could reduce the consumption of nitrate.Moreover,the data showed that the aerobic phosphate uptake of DPBNi was lower than that of anaerobic phosphorus-released sludge in a traditional A/O process.However,there was not much difference between these two kinds of sludge in terms of the total phosphorus uptake quantity and the effluent quality.

  3. Spectrofluorimetric determination of trace nitrite with o-phenylenediamine enhanced by hydroxypropyl-β-cyclodextrin

    Science.gov (United States)

    Guo, Yu-Xian; Zhang, Qing-Feng; Shangguang, Xincheng; Zhen, Guodong

    2013-01-01

    A simple and sensitive spectrofluorimetric method was developed for the determination of nitrite in environmental and food samples. The method was based on the selective reaction of o-phenylenediamine with nitrite in acidic medium to form benzotriazole, which exhibited strong fluorescence at 568 nm with excitation at 420 nm in alkaline medium. The detection limit and sensitivity of the proposed method were improved by hydroxypropyl-β-cyclodextrin through complexation. The linear calibration range for nitrite was 0.04-0.8 μg mL-1 with a detection limit of 13.6 ng mL-1 (S/N = 3.29). The relative standard deviation for ten determinations of 0.1 and 0.4 μg mL-1 nitrite were 1.38% and 2.01%, respectively. Twenty-eight coexistent ions were examined, and no serious interference for most of ions was observed. The proposed method was successfully applied for the determination of nitrite in the water, sausage and soil samples with recoveries of 95.5-108.5%. The results were in good agreement with the recommended AOAC method.

  4. Nitrite accumulation during denitrification depends on the carbon quality and quantity in wastewater treatment with biofilters.

    Science.gov (United States)

    Rocher, Vincent; Laverman, Anniet M; Gasperi, Johnny; Azimi, Sam; Guérin, Sabrina; Mottelet, Stéphane; Villières, Thierry; Pauss, André

    2015-07-01

    This study aims to understand the mechanisms of nitrite appearance during wastewater denitrification by biofilters, focusing on the role of the carbon source. Experiments were carried out at lab-scale (batch tests) and full-scale plant (Parisian plant, capacities of 240,000 m(3) day(-1)). Results showed that the nature of the carbon source affects nitrite accumulation rates. This accumulation is low, 0.05 to 0.10 g N-NO2(-) per g N-NO3(-) eliminated, for alcohols such as methanol, ethanol, or glycerol. The utilization of glycerol leads to fungal development causing clogging of the biofilters. This fungal growth and consequent clogging exclude this carbon source, with little nitrite accumulation, as carbon source for denitrification. Whatever the carbon source, the C/N ratio in the biofilter plays a major role in the appearance of residual nitrite; an optimal C/N ratio from 3.0 to 3.2 allows a complete denitrification without any nitrite accumulation.

  5. Laboratory study on factors influencing nitrogen removal in marble chip biofilters incorporating nitritation and anammox.

    Science.gov (United States)

    Tao, Wendong; Wen, Jianfeng; Norton, Christopher

    2011-01-01

    It remains challenging to integrate nitritation and anammox in ecologically engineered treatment systems such as passive biofilters that are packed with natural materials and have low energy inputs. This study explored the factors influencing nitritation-anammox through parallel operation of two laboratory-scale biofilters packed with large and small marble chips respectively. Clean marble chips (mainly CaCO3) had an alkalinity dissolution rate of 130 mg CaCO3/kg marble d when water pH approached 6.5. Marble chips effectively increased water pH and provided sufficient alkalinity to support nitritation-anammox in the biofilters. Ammonium and total nitrogen removal decreased by 47 and 26%, respectively, when nutrients were not amended to influent. An influent nitrite concentration above 8.9 mg N/L could inhibit anammox in thin biofilms of biofilters. Nitritation-anammox was enhanced with a hydraulic retention time of 2 d relative to 7 d, likely due to enhanced air entrainment. Size of marble chips rarely made a significant difference in nitrogen removal, possibly due to sufficient surface area available for bacterial attachment and alkalinity dissolution.

  6. A novel fiber optic spectrophotometric determination of nitrite using Safranin O and cloud point extraction.

    Science.gov (United States)

    Filik, Hayati; Giray, Derya; Ceylan, Burak; Apak, Reşat

    2011-09-30

    A novel fiber optic spectrophotometric method for nitrite determination in different samples is suggested, based on the reaction of nitrite with Safranin O in acidic medium to form a diazo-safranin, which is subsequently coupled with pyrogallol in alkaline medium to form a highly stable, red azo dye, followed by cloud point extraction (CPE) using a mixed micelle of a nonionic surfactant, Triton X-114, with an anionic surfactant, sodium dodecyl sulphate (SDS). The reaction and extraction conditions (e.g., acidity for diazotization and alkalinity for pyrogallol coupling, and other reagent concentrations, time, and tolerance to other ions) were optimized. Linearity was obeyed in a concentration range up to 230 μg L(-1), and the detection limit of the method is 0.5 μg L(-1) of nitrite ion. The molar absorptivity for nitrite of the Safranin-diazonium salt (ɛ(610 nm) =4 × 10(3) L mol(-1)cm(-1)) existing in literature was greatly enhanced by pyrogallol coupling and CPE enrichment (ɛ(592 nm)=1.39 × 10(5) L mol(-1)cm(-1)). The method was applied to the determination of nitrite in tap water, lake water and milk samples with an optimal preconcentration factor of 20.

  7. Antagonism of Acute Sulfide Poisoning in Mice by Nitrite Anion without Methemoglobinemia.

    Science.gov (United States)

    Cronican, Andrea A; Frawley, Kristin L; Ahmed, Humza; Pearce, Linda L; Peterson, Jim

    2015-07-20

    There are currently no FDA-approved antidotes for H2S/sulfide intoxication. Sodium nitrite, if given prophylactically to Swiss Webster mice, was shown to be highly protective against the acute toxic effects of sodium hydrosulfide (∼LD40 dose) with both agents administered by intraperitoneal injections. However, sodium nitrite administered after the toxicant dose did not detectably ameliorate sulfide toxicity in this fast-delivery, single-shot experimental paradigm. Nitrite anion was shown to rapidly produce NO in the bloodstream, as judged by the appearance of EPR signals attributable to nitrosylhemoglobin and methemoglobin, together amounting to less than 5% of the total hemoglobin present. Sulfide-intoxicated mice were neither helped by the supplemental administration of 100% oxygen nor were there any detrimental effects. Compared to cyanide-intoxicated mice, animals surviving sulfide intoxication exhibited very short knockdown times (if any) and full recovery was extremely fast (∼15 min) irrespective of whether sodium nitrite was administered. Behavioral experiments testing the ability of mice to maintain balance on a rotating cylinder showed no motor impairment up to 24 h post sulfide exposure. It is argued that antagonism of sulfide inhibition of cytochrome c oxidase by NO is the crucial antidotal activity of nitrite rather than formation of methemoglobin.

  8. Properties of aqueous nitrate and nitrite from x-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Jacob W.; Lam, Royce K.; Saykally, Richard J., E-mail: saykally@berkeley.edu [Department of Chemistry, University of California, Berkeley, California 94720 (United States); Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Shih, Orion [National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan (China); Rizzuto, Anthony M. [Department of Chemistry, University of California, Berkeley, California 94720 (United States); Prendergast, David [The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

    2015-08-28

    Nitrate and nitrite ions are of considerable interest, both for their widespread use in commercial and research contexts and because of their central role in the global nitrogen cycle. The chemistry of atmospheric aerosols, wherein nitrate is abundant, has been found to depend on the interfacial behavior of ionic species. The interfacial behavior of ions is determined largely by their hydration properties; consequently, the study of the hydration and interfacial behavior of nitrate and nitrite comprises a significant field of study. In this work, we describe the study of aqueous solutions of sodium nitrate and nitrite via X-ray absorption spectroscopy (XAS), interpreted in light of first-principles density functional theory electronic structure calculations. Experimental and calculated spectra of the nitrogen K-edge XA spectra of bulk solutions exhibit a large 3.7 eV shift between the XA spectra of nitrate and nitrite resulting from greater stabilization of the nitrogen 1s energy level in nitrate. A similar shift is not observed in the oxygen K-edge XA spectra of NO{sub 3}{sup −} and NO{sub 2}{sup −}. The hydration properties of nitrate and nitrite are found to be similar, with both anions exhibiting a similar propensity towards ion pairing.

  9. Microbial mediated iron redox cycling in Fe (hydr)oxides for nitrite removal.

    Science.gov (United States)

    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 NH4(+)-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 NO2(-)-N removal from solution, and reduced most nitrite abiotically to gaseous nitrogen species.

  10. Nitrite is a positive modulator of the Frank-Starling response in the vertebrate heart.

    Science.gov (United States)

    Angelone, Tommaso; Gattuso, Alfonsina; Imbrogno, Sandra; Mazza, Rosa; Tota, Bruno

    2012-06-01

    Evidence from both mammalian and nonmammalian vertebrates indicates that intracardiac nitric oxide (NO) facilitates myocardial relaxation, ventricular diastolic distensibility, and, consequently, the Frank-Starling response, i.e., the preload-induced increase of cardiac output. Since nitrite ion (NO(2)(-)), the major storage pool of bioactive NO, recently emerged as a cardioprotective endogenous modulator, we explored its influence on the Frank-Starling response in eel, frog, and rat hearts, used as paradigms of fish, amphibians, and mammals, respectively. We demonstrated that, like NO, exogenous nitrite improves the Frank-Starling response in all species, as indicated by an increase of stroke volume and stroke work (eel and frog) and of left ventricular (LV) pressure and LVdP/dt max (rat), used as indexes of inotropism. Unlike in frog and rat, in eel, the positive influence of nitrite appeared to be dependent on NO synthase inhibition. In all species, the effect was sensitive to NO scavengers, independent on nitroxyl anion, and mediated by a cGMP/PKG-dependent pathway. Moreover, the nitrite treatment increased S-nitrosylation of lower-molecular-weight proteins in cytosolic and membrane fractions. These results suggest that nitrite acts as a physiological source of NO, modulating through different species-specific mechanisms, the stretch-induced intrinsic regulation of the vertebrate heart.

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

    Science.gov (United States)

    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 (PLactobacillus 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.

  12. Survey the effects of dietary sodium nitrite on the histological changes of the aortic artery in the adult male rats

    Directory of Open Access Journals (Sweden)

    Saeaid Khatamsaz

    2016-05-01

    Full Text Available Background: Because of high consumption of nitrite in processed (fast foods and high level of nitrite in water, soil and ecosystem, nitrite can endanger humans health. In this study the effects of sodium nitrite on aorta was examined in adult male rats. Materials and Methods : In the present study, 30 Wistar adult male rats were randomly divided into three groups of 10, including; control group. First experimental group that received low dose of sodium nitrite (175 mg/kg.bw, second experimental group that received high dose of sodium nitrite (350 mg/kg.bw. They were examined for 60 days. The rats got sodium nitrite through drinking water. At the end of the experiment the rats were taken to the anesthesia jar and based on ether principles, they anesthetized with ether and their blood samples were collected from their hearts. Then their aorta were extracted from their bodies and the tissue sections were prepared for testing tissue changes. Features such as histological features of aorta (morphometric and morphologic features were analyzed. The samples were stained with masson trichrome and Hematoxylin- Eosin methods. The internal media layer was measured with Image tool software. Then the amount of nitrite oxide in their blood were tested. At the end results were analyzed by 17 version of SPSS software and ANOVA test was run. Results: The results of this study showed that thickness of medial layer in two experimental group that received low and high dose of sodium nitrite compared with the control group decreased (p 0.05, and the group that received of high dose of sodium nitrite showed irregular and non- uniform state in aortic media layer. Conclusion: The finding of this study indicated that consumption of sodium nitrite in long term can induce damage in artries tissue.

  13. Photoperiodic stress on nitrite production by splenic macrophages in fresh-water snake Natrix piscator

    Directory of Open Access Journals (Sweden)

    Tripathi Manish Kumar

    2012-05-01

    Full Text Available Changes in day length enhance or suppress component of immune function in individuals of several species. The purpose of the present experiment was to study the role of photoperiodic manipulation on the nitric oxide production by splenic macrophages in the fresh-water snake, Natrix piscator. To study effect of photoperiod, animals were subjected to 24 hour continuous light and continuous dark for 30 days. Animals kept in natural day length served as control. At termination of experiments, animals were sacrificed, and spleen was excised. Macrophages were incubated for 24 hours and nitric oxide production was measured by measuring the nitrite concentration. Nitrite production was significantly decreased to the cultures obtained from the animals kept under continuous light. No change in nitrite concentration was found in animals kept under continuous dark, when compared to the animals kept under natural day length. The possible role of decreased melatonin synthesis in light is suggested to decrease the nitric oxide production.

  14. Role of nitrite in regulation of fetal cephalic circulation in sheep.

    Science.gov (United States)

    Truong, Giang T; Schröder, Hobe J; Liu, Taiming; Zhang, Meijuan; Kanda, Eriko; Bragg, Shannon; Power, Gordon G; Blood, Arlin B

    2014-04-15

    Nitrite has been postulated to provide a reservoir for conversion to nitric oxide (NO), especially in tissues with reduced oxygen levels as in the fetus. Nitrite would thus provide local vasodilatation and restore a balance between oxygen supply and need, a putative mechanism of importance especially in the brain. The current experiments test the hypothesis that exogenous nitrite acts as a vasodilator in the cephalic vasculature of the intact, near term fetal sheep. Fetuses were first instrumented to measure arterial blood pressure and carotid artery blood flow and then studied 4-5 days later while in utero without anaesthesia. Initially l-nitro-arginine (LNNA) was given to block endogenous NO production. Carotid resistance to flow increased 2-fold from 0.54 ± 0.01 (SEM) to 1.20 ± 0.08 mmHg min ml(-1) (in 13 fetuses, P fetal sheep.

  15. Directed Molecular Evolution of Nitrite Oxido-reductase by DNA-shuffling

    Institute of Scientific and Technical Information of China (English)

    JUN-WEN LI; JIN-LAI ZHENG; XIN-WEI WANG; MIN JIN; FU-HUAN CHAO

    2007-01-01

    Objective To develtop directly molecular evolution of nitrite oxido-reductase using DNA-shuffling technique because nitrobacteria grow extremely slow and are unable to nitrify effectively inorganic nitrogen in wastewater treatment. Methods The norB gene coding the nitrite oxido-reductase in nitrobacteria was cloned and sequenced. Then, directed molecular evolution of nitrite oxido-reductase was developed by DNA-shuffling of 15 norB genes from different nitrobacteria. Results After DNA-shuffling with sexual PCR and staggered extension process PCR, the sequence was different from its parental DNA fragments and the homology ranged from 98% to 99%. The maximum nitrification rate of the modified bacterium of X16 by modified bacterium had the same characteristics of its parental bacteria of E. coli and could grow rapidly in normal cultures.Conclusion DNA-shuffling was successfully used to engineer E. coli, which had norB gene and could degrade inorganic nitrogen effectively.

  16. Evaluation of leukocyte esterase and nitrite strip tests to detect spontaneous bacterial peritonitis in cirrhotic patients

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    AIM: To investigate the diagnostic efficacy of leukocyte esterase and nitrite reagent strips for bedside diagnosis of spontaneous bacterial peritonitis (SBP).METHODS: A total of 63 consecutive patients with cirrhotic ascites (38 male, 25 female) tested between April 2005 and July 2006 were included in the study. Bedside reagent strip testing was performed on ascitic fluid and the results compared to manual cell counting and ascitic fluid culture. SBP was defined as having a olymorphonuclear ascites count of ≥ 250/mm3.RESULTS: Fifteen samples showed SBP. The sensitivity,specificity, positive and negative predictive values of the leukocyte esterase reagent strips were; 93%, 100%, 100%, and 98%, respectively. The sensitivity,specificity, positive and negative predictive value of the nitrite reagent strips were 13%, 93%, 40%, and 77%, respectively. The combination of leukocyte esterase and nitrite reagents strips did not yield statistically significant effects on diagnostic accuracy. CONCLUSION: Leukocyte esterase reagent strips may provide a rapid, bedside diagnostic test for SBP.

  17. INCREASED CONCENTRATION OF NITRITE IN SYNOVIAL FLUID AND SERUM SAMPLES IN STEROID INDUCED FEMORAL HEAD NECROSIS

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    To investigate the role of nitric oxide (NO) in steroid-induced femoral head necrosis, NO production was measured indirectly as nitrite in serum and synovial fluid samples from patients with steroid-induced femoral head necrosis together with serum samples from healthy volunteers matched for age and sex. The results showed that:① serum nitrite concentration in patients with femoral head necrosis were significantly lower than that in controls (P<0.001); ② nitrite level of synovial fluid was markedly higher than that of serum. In addition, there was a positive correlation between them (r=0.378,P<0.05). We reach the conclusion:① NO is synthesized by synovium and chondrocytes; ② the decreased NO concentration in serum suggests a protective role in steroid-induced femoral head necrosis.

  18. Effect of wall growth on the kinetic modeling of nitrite oxidation in a CSTR.

    Science.gov (United States)

    Dokianakis, Spiros N; Kornaros, Michael; Lyberatos, Gerasimos

    2006-03-05

    A simple kinetic model was developed for describing nitrite oxidation by autotrophic aerobic nitrifiers in a continuous stirred tank reactor (CSTR), in which mixed (suspended and attached) growth conditions prevail. The CSTR system was operated under conditions of constant nitrite feed concentration and varying volumetric flow rates. Experimental data from steady-state conditions in the CSTR system and from batch experiments were used for the determination of the model's kinetic parameters. Model predictions were verified against experimental data obtained under transient operating conditions, when volumetric flow rate and nitrite feed concentration disturbances were imposed on the CSTR. The presented kinetic modeling procedure is quite simple and general and therefore can also be applied to other mixed growth biological systems.

  19. Electrochemical Determination of Food Preservative Nitrite with Gold Nanoparticles/p-Aminothiophenol-Modified Gold Electrode

    Science.gov (United States)

    Üzer, Ayşem; Sağlam, Şener; Can, Ziya; Erçağ, Erol; Apak, Reşat

    2016-01-01

    Due to the negative impact of nitrate and nitrite on human health, their presence exceeding acceptable levels is not desired in foodstuffs. Thus, nitrite determination at low concentrations is a major challenge in electroanalytical chemistry, which can be achieved by fast, cheap, and safe electrochemical sensors. In this work, the working electrode (Au) was functionalized with p-aminothiophenol (p-ATP) and modified with gold nanoparticles (Au-NPs) to manufacture the final (Au/p-ATP-Aunano) electrode in a two-step procedure. In the first step, p-ATP was electropolymerized on the electrode surface to obtain a polyaminothiophenol (PATP) coating. In the second step, Au/p-ATP-Aunano working electrode was prepared by coating the surface with the use of HAuCl4 solution and cyclic voltammetry. Determination of aqueous nitrite samples was performed with the proposed electrode (Au/p-ATP-Aunano) using square wave voltammetry (SWV) in pH 4 buffer medium. Characteristic peak potential of nitrite samples was 0.76 V, and linear calibration curves of current intensity versus concentration was linear in the range of 0.5–50 mg·L−1 nitrite with a limit of detection (LOD) of 0.12 mg·L−1. Alternatively, nitrite in sausage samples could be colorimetrically determined with high sensitivity by means of p-ATP‒modified gold nanoparticles (AuNPs) and naphthylethylene diamine as coupling agents for azo-dye formation due to enhanced charge-transfer interactions with the AuNPs surface. The slopes of the calibration lines in pure NO2− solution and in sausage sample solution, to which different concentrations of NO2− standards were added, were not significantly different from each other, confirming the robustness and interference tolerance of the method. The proposed voltammetric sensing method was validated against the colorimetric nanosensing method in sausage samples. PMID:27490543

  20. Researches concerning nitrates and nitrites accumulation in carrots, along of the vegetation stages

    Directory of Open Access Journals (Sweden)

    Monica NEGREA

    2008-05-01

    Full Text Available The presented paper deals with the determination of nitrates and nitrites content in carrots, in different vegetation stages of the carrot culture. High nitrates and nitrites concentration in vegetables is mainly due to excessive nitrogen content in the soil system, thus deteriorating the nutritional and hygienic values of products and complicating the processing and storage. The determination was tested on carrot samples assayed from an experimental field set up near Timisoara. In experimental field, to the carrot culture was administrated different doses of fertilizers (NPK and the samples for analysis were assayed in different phases of vegetation. The obtained results indicated that the highest level of nitrate in carrots was found to the variant b3 (N150P90K90 in experimental field, who was above maximum limit allowed (LMA. Maximum limit allowed for nitrates in carrots, in accordance with ORDER No. 293/640/2001-1/2002 regarding security and quality conditions for vegetables and fresh fruits for human consumption is 400 ppm. For all other samples of carrots the nitrates level was below of LMA. The nitrite content grows in case of fertilizer administration during the whole vegetation stages of the plant. In variant N150P90K90 the nitrite content was above (LMA in carrot samples in all stages of vegetation. The nitrite content in carrots should not exceed 1-2 ppm. Nitrate and nitrite content in carrots was done with the help of High Performance Liquid Chromatography (HPLC in the Laboratory for the Measurement of Residues of the Department of Agro-techniques of the U.S.A-V.M.B in Timisoara.

  1. Electrochemical Determination of Food Preservative Nitrite with Gold Nanoparticles/p-Aminothiophenol-Modified Gold Electrode

    Directory of Open Access Journals (Sweden)

    Ayşem Üzer

    2016-08-01

    Full Text Available Due to the negative impact of nitrate and nitrite on human health, their presence exceeding acceptable levels is not desired in foodstuffs. Thus, nitrite determination at low concentrations is a major challenge in electroanalytical chemistry, which can be achieved by fast, cheap, and safe electrochemical sensors. In this work, the working electrode (Au was functionalized with p-aminothiophenol (p-ATP and modified with gold nanoparticles (Au-NPs to manufacture the final (Au/p-ATP-Aunano electrode in a two-step procedure. In the first step, p-ATP was electropolymerized on the electrode surface to obtain a polyaminothiophenol (PATP coating. In the second step, Au/p-ATP-Aunano working electrode was prepared by coating the surface with the use of HAuCl4 solution and cyclic voltammetry. Determination of aqueous nitrite samples was performed with the proposed electrode (Au/p-ATP-Aunano using square wave voltammetry (SWV in pH 4 buffer medium. Characteristic peak potential of nitrite samples was 0.76 V, and linear calibration curves of current intensity versus concentration was linear in the range of 0.5–50 mg·L−1 nitrite with a limit of detection (LOD of 0.12 mg·L−1. Alternatively, nitrite in sausage samples could be colorimetrically determined with high sensitivity by means of p-ATP‒modified gold nanoparticles (AuNPs and naphthylethylene diamine as coupling agents for azo-dye formation due to enhanced charge-transfer interactions with the AuNPs surface. The slopes of the calibration lines in pure NO2− solution and in sausage sample solution, to which different concentrations of NO2− standards were added, were not significantly different from each other, confirming the robustness and interference tolerance of the method. The proposed voltammetric sensing method was validated against the colorimetric nanosensing method in sausage samples.

  2. Electrochemical Determination of Food Preservative Nitrite with Gold Nanoparticles/p-Aminothiophenol-Modified Gold Electrode.

    Science.gov (United States)

    Üzer, Ayşem; Sağlam, Şener; Can, Ziya; Erçağ, Erol; Apak, Reşat

    2016-08-02

    Due to the negative impact of nitrate and nitrite on human health, their presence exceeding acceptable levels is not desired in foodstuffs. Thus, nitrite determination at low concentrations is a major challenge in electroanalytical chemistry, which can be achieved by fast, cheap, and safe electrochemical sensors. In this work, the working electrode (Au) was functionalized with p-aminothiophenol (p-ATP) and modified with gold nanoparticles (Au-NPs) to manufacture the final (Au/p-ATP-Aunano) electrode in a two-step procedure. In the first step, p-ATP was electropolymerized on the electrode surface to obtain a polyaminothiophenol (PATP) coating. In the second step, Au/p-ATP-Aunano working electrode was prepared by coating the surface with the use of HAuCl₄ solution and cyclic voltammetry. Determination of aqueous nitrite samples was performed with the proposed electrode (Au/p-ATP-Aunano) using square wave voltammetry (SWV) in pH 4 buffer medium. Characteristic peak potential of nitrite samples was 0.76 V, and linear calibration curves of current intensity versus concentration was linear in the range of 0.5-50 mg·L(-1) nitrite with a limit of detection (LOD) of 0.12 mg·L(-1). Alternatively, nitrite in sausage samples could be colorimetrically determined with high sensitivity by means of p-ATP‒modified gold nanoparticles (AuNPs) and naphthylethylene diamine as coupling agents for azo-dye formation due to enhanced charge-transfer interactions with the AuNPs surface. The slopes of the calibration lines in pure NO₂(-) solution and in sausage sample solution, to which different concentrations of NO₂(-) standards were added, were not significantly different from each other, confirming the robustness and interference tolerance of the method. The proposed voltammetric sensing method was validated against the colorimetric nanosensing method in sausage samples.

  3. [Presence of nitrates and nitrites in baker's products and in certain other flour products].

    Science.gov (United States)

    Nabrzyski, M; Gajewska, R; Ganowiak, Z

    1990-01-01

    The results of the study demonstrated that the content of nitrates and nitrites in various baker's products varied from 0.96 (in wheat rolls and baguettes) to 44.07 mg KO3/kg in pumpernickel bread. In wholemeal bread, village bread, tourist bread, rye brown bread and Graham bread the content of these compounds was from 1.46 to 27.10 mg KNO3/kg. The mean content of nitrites in these bread sorts was 1.76 mg NaNo2/kg, range 0.10-4.40 mg NaNo2/kg. In white wheat flours (Wrocław flour, cake flour and Poznań flour) the content of nitrates ranged from 1.10 to 19.08 mg KNO3/kg, and in the dishes produced from them in household was from 0.50 to 16.33 mg KNO3/kg. The content of nitrites in these flours was in the range from 0.00 to 4.16 mg NaNo2/kg, and in the products prepared from them it was from 0.00 to 1.60 mg NaNO2/kg. Eleven types were tested also of popular biscuits, wafers, gingerbread and hard cakes in which the content of nitrates was from 3.66 to 17.72 mg/kg, and that of nitrites was from 0.00 to 8.80 mg NaNo2/kg. Considering the average consumption of these products per one person in the seashore region and the mean values of nitrates and nitrites it was calculated that they provided daily about 3.9 mg KNO3 and 0.4 NaNo2, that is about 1.8% of nitrates and 7.7% of nitrites consumed by adults in daily food ration.

  4. On the optimum conditions for the reduction of nitrate to nitrite by cadmium.

    Science.gov (United States)

    Nydahl, F

    1976-05-01

    The variables of direct importance in the reduction of nitrate to nitrite by a metallic reductant such as cadmium used in a reductor column are discussed with special reference to the determination of nitrate as nitrite in very dilute solutions, e.g., natural waters. As a result of these considerations the effect of flow-rate (expressed as bed-volumes min ), pH, temperature, chloride concentration and various types of reductor cadmium on the yield of nitrite is investigated. The effect of dissolved oxygen in the sample solution on pH and cadmium concentration in the reduced solution is demonstrated. At constant pH a maximum yield of nitrite is obtained at a certain flow-rate, which is explained as the result of a rapid formation and simultaneously proceeding slow reduction of nitrite. With increasing pH this maximum is shifted to lower flow-rates, and grows broader whilst the yield at maximum approaches 100%; at pH 9.5 a yield of 99.9 +/- 0.1% is obtained. The temperature has little effect on the reduction rate in the interval 20-30 degrees but at 10 degrees the reduction is noticeably slower. Chloride ions have a strongly retarding effect on the reduction rate but the yield at maximum is not affected. Electrolytically precipitated cadmium, filings of pure cadmium or amalgamated pure cadmium all give practically the same yield at maximum though some differences in reduction rate are observed. Impure cadmium or copper-cadmium and silver-cadmium, owing to the formation of galvanic cells with higher reducing power, give a high reduction rate, which also applies to nitrite, causing a poorer yield at maximum. The practical consequences of the results are thoroughly discussed.

  5. Modeling pitting corrosion of iron exposed to alkaline solutions containing nitrate and nitrite

    Science.gov (United States)

    Chen, Lifeng

    2001-07-01

    Pitting corrosion could be extremely serious for dilute high-level radioactive waste stored or processed in carbon steel tanks at the Savannah River Site. In these solutions, nitrate is an aggressive ion with respect to pitting of carbon steel while nitrite can be used as an inhibitor. Excessive additions of nitrite increase the risk of generating unstable nitrogen compounds during waste processing, and insufficient additions of nitrite could increase the risk of corrosion-induced failure. Thus there are strong incentives to obtain a fundamental understanding of the role of nitrite in pitting corrosion prevention with these solution chemistries. In this dissertation, both a 1-D and a 2-D model are used to study the pitting mechanism as a function of nitrite/nitrate ratios. The 1-D model used BAND(J) to test a reaction mechanism for the passivation behavior by comparing the predicted Open Circuit Potential (OCP) with OCP data from experiments at different NO2-/NO3- ratio. The model predictions are compared with Cyclic Potentiodynamic Polarization (CPP) experiments. A 2-D model was developed for the propagation of a pit in iron by writing subroutines for finite element software of GAMBIT and FIDAP. Geometrically distributed anodic and cathodic reactions are assumed. The results show three partial explanations describing the inhibition influence of nitrite to iron corrosion: the competing reduction reaction of nitrate to nitrite, the formation of Fe(OH)+, and the function of the porous film. The current distributions and the effect of porosity of the film on pH are also explained. The calculation results also show that rate of pit growth decreases as the pit diameter increases until it reaches a constant value. The profile of the local current density on the pit wall is parabolic for small pits and it changes to a linear distribution for large pits. The model predicts that addition of nitrite will decrease the production of ferrous ions and those can prevent iron from

  6. Enhancement of Nitrite Reduction Kinetics on Electrospun Pd-Carbon Nanomaterial Catalysts for Water Purification.

    Science.gov (United States)

    Ye, Tao; Durkin, David P; Hu, Maocong; Wang, Xianqin; Banek, Nathan A; Wagner, Michael J; Shuai, Danmeng

    2016-07-20

    We report a facile synthesis method for carbon nanofiber (CNF) supported Pd catalysts via one-pot electrospinning and their application for nitrite hydrogenation. A mixture of Pd acetylacetonate (Pd(acac)2), polyacrylonitrile (PAN), and nonfunctionalized multiwalled carbon nanotubes (MWCNTs) was electrospun and thermally treated to produce Pd/CNF-MWCNT catalysts. The addition of MWCNTs with a mass loading of 1.0-2.5 wt % (to PAN) significantly improved nitrite reduction activity compared to the catalyst without MWCNT addition. The results of CO chemisorption confirmed that the addition of MWCNTs increased Pd exposure on CNFs and hence improved catalytic activity.

  7. Allosteric control of internal electron transfer in cytochrome cd1 nitrite reductase

    DEFF Research Database (Denmark)

    Farver, Ole; Kroneck, Peter M H; Zumft, Walter G

    2003-01-01

    Cytochrome cd1 nitrite reductase is a bifunctional multiheme enzyme catalyzing the one-electron reduction of nitrite to nitric oxide and the four-electron reduction of dioxygen to water. Kinetics and thermodynamics of the internal electron transfer process in the Pseudomonas stutzeri enzyme have...... been studied and found to be dominated by pronounced interactions between the c and the d1 hemes. The interactions are expressed both in dramatic changes in the internal electron-transfer rates between these sites and in marked cooperativity in their electron affinity. The results constitute a prime...... example of intraprotein control of the electron-transfer rates by allosteric interactions....

  8. Reductive cleavage of nitrite to form terminal uranium mono-oxo complexes.

    Science.gov (United States)

    Lewis, Andrew J; Carroll, Patrick J; Schelter, Eric J

    2013-01-09

    Uranium terminal mono-oxo complexes are prepared with a unique activation of nitrite following reductive cleavage of an N-O bond with loss of nitric oxide. The thermodynamic driving force of U═O bond formation differentiates this reactivity from known mechanisms of nitrite reduction, which are typically mediated by proton transfer. Mechanistic details are explored by DFT supporting a simple homolytic cleavage pathway from a κ(1)-ONO bound intermediate. Complexes of the formula U(VI)OX[N(SiMe(3))(2)](3) are formed providing a trigonal bipyramidal framework into which ligands trans to the U═O bond may be installed.

  9. Determination of nitrite ion and sulfanilic and orthanilic acids by differential pulse polarography

    Energy Technology Data Exchange (ETDEWEB)

    Sulaiman, S.T.

    1984-11-01

    The nitrite ion can be determined with a high degree of accuracy and sensitivity by differential pulse polarography utilizing the rapid and quantitative reaction between the nitrite ion and sulfanilic acid or orthanilic acid at pH 1.5. The experimental detection limit is shown to be 8.6 X 10/sup -8/ M (as NO/sub 2//sup -/) in simple aqueous solution. The method is further used to determine concentrations of sulfanilic acid down to 4 X 10/sup -7/ M and orthanilic acid down to 1.6 X 10/sup -6/ M under optimum conditions.

  10. Comparative Behaviour of Nitrite and Nitrate for the Protection of Rebar Corrosion

    Science.gov (United States)

    Ahmad, Altaf; Kumar, Anil

    2016-10-01

    Corrosion of rebar steel due to environmental causes has been studied through various approaches, and among the protection techniques use of inhibitors has gained encouragement. Nitrites and nitrates of sodium have gained sufficient scientific coverage. Recently, nitrites and nitrates of calcium have been verified in some studies, which, however, needs further experimentation through different angles. Simple polarization technique has been utilized in the present study to compare inhibitive efficiency of these salts of sodium and calcium, which indicate that calcium salts are more efficient.

  11. Iron-Doped Titania Nanoparticles for the Photocatalytic Oxidative Degradation of Nitrite

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Iron-doped titania nanoparticles exhibit a higher photocatalytic activity than pure TiO2 for the degradation of nitrite. The optimum Fe-doped content in terms of activity is approximately 0. 5 %. The increase in photoactivity is probably due to the higher adsorption and the inhibition of electron-hole recombination. The photocatalytic oxidation reaction of nitrite over the Fe-doped TiO2 catalyst follows zero-order kinetics, which is different from that over pure TiO2. The reaction rate decreases linearly with the increase of the pH of the solution.

  12. Aldehyde-Selective Wacker-Type Oxidation of Unbiased Alkenes Enabled by a Nitrite Co-Catalyst

    KAUST Repository

    Wickens, Zachary K.

    2013-09-13

    Breaking the rules: Reversal of the high Markovnikov selectivity of Wacker-type oxidations was accomplished using a nitrite co-catalyst. Unbiased aliphatic alkenes can be oxidized with high yield and aldehyde selectivity, and several functional groups are tolerated. 18O-labeling experiments indicate that the aldehydic O atom is derived from the nitrite salt.

  13. Evaluation of the nitrite and leukocyte esterase activity tests for the diagnosis of acute symptomatic urinary tract infection in men.

    NARCIS (Netherlands)

    Koeijers, J.J.; Kessels, A.G.H.; Nys, S.; Bartelds, A.; Donker, G.; Stobberingh, E.; Verbon, A.

    2007-01-01

    For 422 male patients with symptoms indicative of a urinary tract infection, nitrite and leukocyte esterase activity dipstick test results were compared with results of culture of urine samples. The positive predictive value of a positive nitrite test result was 96%. Addition of results of the leuko

  14. Detection of nitrate/nitrite bioavailability in wastewater using a luxCDABE-based Klebsiella oxytoca bioluminescent bioreporter.

    Science.gov (United States)

    Abd-El-Haleem, Desouky; Ripp, Steven; Zaki, Sahar; Sayler, Gary S

    2007-08-01

    In the present study, we have constructed a bioluminescent bioreporter for the assessment of nitrate/nitrite bioavailability in wastewater. Specifically, an approximately 500-bp DNA fragment containing a nitrate/nitrite-activated nasR-like promoter (regulating expression of genes encoding nitrite reductase in the genus Klebsiella) was fused upstream of the Vibrio fischeri luxCDABE gene cassette in a modified mini-Tn5 vector. Characterization of this strain, designated W6-1, yielded dose-dependent increased bioluminescence coincident with increased nitrate, nitrite, and ammonium added to the growth medium from 1 to 11 ppm. Bioluminescence in response to nitrogen species addition was light dependent up to 10, 7, and 8 ppm with nitrate, nitrite, and ammonium, respectively. This response was linear in the range from 1 to 8 ppm for nitrate (R2 = 0.98), 1 to 6 ppm for nitrite (R2 = 0.99), and 1 to 7 ppm for ammonium (R2 = 0.99). A significant bioluminescent response was also recorded when strain W6-1 was incubated with slurries from aged, nitrate/nitrite contaminated wastewater. Thus, bioreporter strain W6-1 can be used to elucidate factors that constrain the use of nitrate/nitrite in wastewaters.

  15. Photolysis of n-butyl nitrite and isoamyl nitrite at 355 nm: A time-resolved Fourier transform infrared emission spectroscopy and ab initio study

    CERN Document Server

    Ji, Min; Zhang, Qun; Chen, Yang

    2009-01-01

    We report on the photodissociation dynamics study of n-butyl nitrite (n-C_4H_9ONO) and isoamyl nitrite ((CH_3)_2C_3H_5ONO) by means of time-resolved Fourier transform infrared (TR-FTIR) emission spectroscopy. The obtained TR-FTIR emission spectra of the nascent NO fragments produced in the 355-nm laser photolysis of the two alkyl nitrite species showed an almost identical rotational temperature and vibrational distributions of NO. In addition, a close resemblance between the two species was also found in the measured temporal profiles of the IR emission of NO and the recorded UV absorption spectra. The experimental results are consistent with our ab initio calculations using the time-dependent density functional theory at the B3LYP/6-311G(d,p) level, which indicate that the substitution of one of the two {gamma}-H atoms in n-C_4H_9ONO with a methyl group to form (CH_3)_2C_3H_5ONO has only a minor effect on the photodissociation dynamics of the two molecules.

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

    Science.gov (United States)

    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

  17. De novo biofilm community assembly from tap water source communities favors Nitrotoga over Nitrospira under elevated nitrite surface loading

    DEFF Research Database (Denmark)

    Kinnunen, Marta; Dechesne, Arnaud; Albrechtsen, Hans-Jørgen;

    -through biofilm system to continuous immigration from a tap water metacommunity while applying different nitrite surface loading rates. After 63 days of operation, we extracted biofilms and analyzed the community composition via Illumina MiSeq targeting the 16S rRNA gene. Previous studies have shown......Four main processes are considered to drive microbial community assembly: selection, drift, dispersal and speciation. These processes occur simultaneously, but the extent to which each process contributes to community assembly is unclear in natural communities. We exposed a high-throughput flow...... that Nitrospira is the dominant nitrite oxidizing genus in low nitrite environments. Hence, we postulated that by elevating the nitrite surface loading we would select for NOB with lower nitrite affinity than Nitrospira. We observed different dominant NOB species under different loading rates. While...

  18. Achieving the nitrite pathway using FA inhibition and process control in UASB-SBR system removing nitrogen from landfill leachate

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    An up-flow sludge blanket(UASB) and sequencing batch reactor(SBR) system was introduced to remove organics and nitrogen from landfill leachate.The synergetic effect of free ammonia(FA) inhibition and process control was used to achieve the nitrite pathway in the SBR.In previous research,inhibition of FA on nitrite oxidizing bacteria(NOB) activity has been revealed and the process control parameters(DO,ORP and pH) exactly indicate the end-point of nitritation.The method was implemented in the SBR achieving stable nitrogen removal via the nitrite pathway from landfill leachate.The degree of nitrite accumulation during the nitritation was monitored along with the simultaneous and advanced removal of organics and nitrogen in the UASB-SBR system.The nitrifying bacteria community was quantitatively analyzed by fluorescence in situ hybridization(FISH) techniques.Batch tests were carried out to investigate the denitritation kinetics of microbial bacteria in the SBR.Experimental results showed that the nitrite pathway could be repeatedly and reliably achieved by synergetic effect of FA inhibition and process control.FISH analysis showed the dominant nitrifying bacteria were ammonia-oxidizing β-Proteobacteria. Relationship between nitrite concentration and nitrite reduction rate followed the Monod-type equation.The maximum specific nitrite utilization rate(k) and half-velocity constant(Ks) were calculated as 0.44 gN gVSS-1d-1and 15.8 mg L-1,respectively.

  19. Comparison of endogenous metabolism during long-term anaerobic starvation of nitrite/nitrate cultivated denitrifying phosphorus removal sludges.

    Science.gov (United States)

    Wang, Yayi; Zhou, Shuai; Wang, Hong; Ye, Liu; Qin, Jian; Lin, Ximao

    2015-01-01

    Denitrifying phosphorus removal (DPR) by denitrifying phosphorus-accumulating organisms (DPAOs) is a promising approach for reducing energy and carbon usage. However, influent fluctuations or interruptions frequently expose the DPAOs biomass to starvation conditions, reducing biomass activity and amount, and ultimately degrading the performance of DPR. Therefore, a better understanding of the endogenous metabolism and recovery ability of DPAOs is urgently required. In the present study, anaerobic starvation (12 days) and recovery were investigated in nitrite- and nitrate-cultivated DPAOs at 20 ± 1 °C. The cell decay rates in nitrite-DPAOs sludges from the end of the anaerobic and aerobic phase were 0.008 day⁻¹ and 0.007 day⁻¹, respectively, being 64% and 68% lower than those of nitrate-DPAOs sludges. Nitrite-DPAOs sludges also recovered more rapidly than nitrate-DPAOs sludge after 12 days of starvation. The maintenance energy of nitrite-DPAOs sludges from the end of the anaerobic and aerobic phase were approximately 31% and 34% lower, respectively, than those of nitrate-DPAOs sludges. Glycogen and polyphosphate (poly-P) sequentially served as the main maintenance energy sources in both nitrite-and nitrate-DPAOs sludges. However, the transformation pathway of the intracellular polymers during starvation differed between them. Nitrate-DPAOs sludge used extracellular polymeric substances (EPS) (mainly polysaccharides) as an additional maintenance energy source during the first 3 days of starvation. During this phase, EPS appeared to contribute to 19-27% of the ATP production in nitrate-DPAOs, but considerably less to the cell maintenance of nitrite-DPAOs. The high resistance of nitrite-DPAOs to starvation might be attributable to frequent short-term starvation and exposure to toxic substances such as nitrite/free nitrous acids in the parent nitrite-fed reactor. The strong resistance of nitrite-DPAOs sludge to anaerobic starvation may be exploited in P removal

  20. Effects of Lactic Acid Bacteria on Residual Nitrite in a Summer Style Sausage.

    Science.gov (United States)

    1984-01-01

    the American Type Culture Collection Culture ATCC Number Lactobacillus acidophilus 4365 0 Lactobacillus casei E393 Lactobacillus leichmannii 4797...200 400 600 800 1000 200 400 600 800 1000 * Control -h Lactobacillus acidophilus ’a Lactobacillus casela Lactobacillus leichmanniia... Lactobacillus leichmannii, Streptococcus faecalis, and several atypical lactobacilli isolated from fresh beef and mutton reduced 200-1000 ppm nitrite

  1. Photolysis of Nitrate and Nitrite in Artificial Snow and Artificial Ice

    Science.gov (United States)

    Shi, W.; Green, S. A.

    2003-12-01

    It is well known that nitrate and nitrite undergo photolysis in aqueous solution. Recent studies show that these reactions are likely to occur in natural snow as well. Therefore it is of interest to measure rates of photolysis of nitrate and nitrite in snow and ice. In this study artificial snow was made by spraying a solution onto the wall of a reservoir containing liquid nitrogen. Artificial snow and ice were irradiated in a sealed quartz tube with a UV lamp and production of hydroxyl radicals was quantified. Hydroxyl radicals produced in these processes react with dimethyl sulfoxide to release methyl radicals, which were trapped by 3-amino-2,2,5,5-tetramethyl-1-pyrrolidinyloxy free radical (3AP). The 3AP-CH3 compound was later derivatized to produce a highly fluorescent adduct, which was measured by HPLC. Snow produced the highest yield of hydroxyl radicals and ice the lowest. Nitrite had higher yield than nitrate. The calculation of photolysis rates for nitrate and nitrite in snow and ice is discussed.

  2. Positive role of nitrite as electron acceptor on anoxic denitrifying phosphorus removal process

    Institute of Scientific and Technical Information of China (English)

    HUANG RongXin; LI Dong; LI XiangKun; BAO LinLin; JIANG AnXi; ZHANG Jie

    2007-01-01

    Literatures revealed that the electron acceptor-nitrite could be inhibitory or toxic in the denitrifying phosphorus removal process.Batch test experiments were used to investigate the inhibitory effect during the anoxic condition.The inoculated activated sludge was taken from a continuous double- sludge denitrifying phosphorus and nitrogen removal system.Nitrite was added at the anoxic stage.One time injection and sequencing batch injection were carried on in the denitrifying dephosphorus procedure.The results indicated that the nitrite concentration higher than 30 mg/L would inhibit the anoxic phosphate uptake severely, and the threshold inhibitory concentration was dependent on the characteristics of the activated sludge and the operating conditions; instead, lower than the inhibitory concentration would not be detrimental to anoxic phosphorus uptake, and it could act as good electron acceptor for the anoxic phosphate accumulated.Positive effects performed during the denitrifying biological dephosphorus all the time.The utility of nitrite as good electron acceptor would provide a new feasible way in the denitrifying phosphorus process.

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

    DEFF Research Database (Denmark)

    Zhang, Yifeng; Angelidaki, Irini

    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...

  4. Tetrazine-based chemistry for nitrite determination in a paper microfluidic device.

    Science.gov (United States)

    Ortiz-Gomez, Inmaculada; Ortega-Muñoz, Mariano; Salinas-Castillo, Alfonso; Álvarez-Bermejo, José Antonio; Ariza-Avidad, Maria; de Orbe-Payá, Ignacio; Santoyo-Gonzalez, Francisco; Capitan-Vallvey, Luis Fermin

    2016-11-01

    We present a new chemistry to determine nitrites implemented in a microfluidic paper-based analytical device (µPAD). The device is fabricated in cellulose paper with a sample reception area and three replicate detection areas with recognition chemistry immobilized by adsorption. The method involves the use of nitrite in an acid medium reaction to generate nitrous acid, which produces the oxidation of s-dihydrotetrazine: 1,2-dihydro-3,6-bis(3,5-dimethyl-1H-pyrazol-1-yl)-1,2,4,5-tetrazine (DHBPTz), which change the detection zone from colorless to pink. We used a digital camera and smartphone for the quantitative analysis of nitrite with the color coordinate S of the HSV color space as the analytical parameter. Parameters such as concentration and volume of s-dihydrotetrazine, pH, sample volume and reaction time were studied. The detection limit for this method is 1.30µM nitrite. To estimate the selectivity of the method an interference study of common ions in water samples was performed. The procedure was applied to natural water and compared with reference procedures.

  5. Colorimetric determination of nitrate plus nitrite in water by enzymatic reduction, automated discrete analyzer methods

    Science.gov (United States)

    Patton, Charles J.; Kryskalla, Jennifer R.

    2011-01-01

    This report documents work at the U.S. Geological Survey (USGS) National Water Quality Laboratory (NWQL) to validate enzymatic reduction, colorimetric determinative methods for nitrate + nitrite in filtered water by automated discrete analysis. In these standard- and low-level methods (USGS I-2547-11 and I-2548-11), nitrate is reduced to nitrite with nontoxic, soluble nitrate reductase rather than toxic, granular, copperized cadmium used in the longstanding USGS automated continuous-flow analyzer methods I-2545-90 (NWQL laboratory code 1975) and I-2546-91 (NWQL laboratory code 1979). Colorimetric reagents used to determine resulting nitrite in aforementioned enzymatic- and cadmium-reduction methods are identical. The enzyme used in these discrete analyzer methods, designated AtNaR2 by its manufacturer, is produced by recombinant expression of the nitrate reductase gene from wall cress (Arabidopsis thaliana) in the yeast Pichia pastoris. Unlike other commercially available nitrate reductases we evaluated, AtNaR2 maintains high activity at 37°C and is not inhibited by high-phenolic-content humic acids at reaction temperatures in the range of 20°C to 37°C. These previously unrecognized AtNaR2 characteristics are essential for successful performance of discrete analyzer nitrate + nitrite assays (henceforth, DA-AtNaR2) described here.

  6. Intake of nitrate and nitrite and the risk of gastric cancer: A prospective cohort study

    NARCIS (Netherlands)

    Loon, A.J.M. van; Botterweck, A.A.M.; Goldbohm, R.A.; Brants, H.A.M.; Klaveren, J.D. van; Brandt, P.A. van den

    1998-01-01

    The association between the intake of nitrate or nitrite and gastric cancer risk was investigated in a prospective cohort study started in 1986 in the Netherlands, of 120,852 men and women aged 55-69 years. At baseline, data on dietary intake, smoking habits and other covariates were collected by me

  7. Nitrite and Nitrate Content in Meat Products and Estimated Intake in Denmark From 1998 to 2006

    DEFF Research Database (Denmark)

    Leth, Torben; Fagt, Sisse; Nielsen, S.

    2008-01-01

    The content of nitrite and nitrate in cured meat products has been monitored in Denmark seven times between 1995 and 2006. The maximum permitted added amounts of sodium nitrite in Denmark (60 mg kg(-1) for most products up to 150 mg kg(-1) for special products) have not been exceeded, except...... for a few samples back in 2002. The intake, mean and intake distribution of sodium nitrite have been calculated from 1998 to 2006 with data from the Danish dietary survey conducted in 2000-02 on Danes from four to 75 years of age. The amounts used by industry have been relatively stable through the whole...... period with levels varying between 6 and 20 mg sodium nitrite kg(-1) with sausages, meat for open sandwiches and salami-type sausages being the greatest contributors. The mean intake of sodium nitrate was around 1 mg day(-1), which is very low compared with the total intake of 61 mg day(-1). The mean...

  8. Nitrate and nitrite in the diet: how to assess their benefit and risk for human health.

    Science.gov (United States)

    Habermeyer, Michael; Roth, Angelika; Guth, Sabine; Diel, Patrick; Engel, Karl-Heinz; Epe, Bernd; Fürst, Peter; Heinz, Volker; Humpf, Hans-Ulrich; Joost, Hans-Georg; Knorr, Dietrich; de Kok, Theo; Kulling, Sabine; Lampen, Alfonso; Marko, Doris; Rechkemmer, Gerhard; Rietjens, Ivonne; Stadler, Richard H; Vieths, Stefan; Vogel, Rudi; Steinberg, Pablo; Eisenbrand, Gerhard

    2015-01-01

    Nitrate is a natural constituent of the human diet and an approved food additive. It can be partially converted to nitrogen monoxide, which induces vasodilation and thereby decreases blood pressure. This effect is associated with a reduced risk regarding cardiovascular disease, myocardial infarction, and stroke. Moreover, dietary nitrate has been associated with beneficial effects in patients with gastric ulcer, renal failure, or metabolic syndrome. Recent studies indicate that such beneficial health effects due to dietary nitrate may be achievable at intake levels resulting from the daily consumption of nitrate-rich vegetables. N-nitroso compounds are endogenously formed in humans. However, their relevance for human health has not been adequately explored up to now. Nitrate and nitrite are per se not carcinogenic, but under conditions that result in endogenous nitrosation, it cannot be excluded that ingested nitrate and nitrite may lead to an increased cancer risk and may probably be carcinogenic to humans. In this review, the known beneficial and detrimental health effects related to dietary nitrate/nitrite intake are described and the identified gaps in knowledge as well as the research needs required to perform a reliable benefit/risk assessment in terms of long-term human health consequences due to dietary nitrate/nitrite intake are presented.

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

    DEFF Research Database (Denmark)

    Zhang, Yifeng; Angelidaki, Irini

    2012-01-01

    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 ...

  10. Unsupported PVA- and PVP-stabilized Pd nanoparticles as catalyst for nitrite hydrogenation in aqueous phase

    NARCIS (Netherlands)

    Zhao, Y.; Baeza, J.A.; Koteswara Rao, N.; Calvo, L.; Gilarranz, M.A.; Li, Y.D.; Lefferts, L.

    2014-01-01

    Pd colloids stabilized with polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP) have been prepared, characterized with TEM, zeta potential measurements, CO chemisorption in aqueous phase, and ATR-IR spectroscopy using CO as a probe molecule, and finally tested for performance in nitrite hydrogena

  11. Electrochemical Single‐Molecule AFM of the Redox Metalloenzyme Copper Nitrite Reductase in Action

    DEFF Research Database (Denmark)

    Hao, Xian; Zhang, Jingdong; Christensen, Hans Erik Mølager;

    2012-01-01

    We studied the electrochemical behavior of the redox metalloenzyme copper nitrite reductase (CNiR, Achromobacter xylosoxidans) immobilized on a Au(111)‐electrode surface modified by a self‐assembled cysteamine molecular monolayer (SAM) using a combination of cyclic voltammetry and electrochemical...

  12. Simultaneous Voltammetric/Amperometric Determination of Sulfide and Nitrite in Water at BDD Electrode

    Directory of Open Access Journals (Sweden)

    Anamaria Baciu

    2015-06-01

    Full Text Available This work reported new voltammetric/amperometric-based protocols using a commercial boron-doped diamond (BDD electrode for simple and fast simultaneous detection of sulfide and nitrite from water. Square-wave voltammetry operated under the optimized working conditions of 0.01 V step potential, 0.5 V modulation amplitude and 10 Hz frequency allowed achieving the best electroanalytical parameters for the simultaneous detection of nitrite and sulfide. For practical in-field detection applications, the multiple-pulsed amperometry technique was operated under optimized conditions, i.e., −0.5 V/SCE for a duration of 0.3 s as conditioning step, +0.85 V/SCE for a duration of 3 s that assure the sulfide oxidation and +1.25 V/SCE for a duration of 0.3 s, where the nitrite oxidation occurred, which allowed the simultaneously detection of sulfide and nitrite without interference between them. Good accuracy was found for this protocol in comparison with standardized methods for each anion. Also, no interference effect was found for the cation and anion species, which are common in the water matrix.

  13. Simultaneous Voltammetric/Amperometric Determination of Sulfide and Nitrite in Water at BDD Electrode

    Science.gov (United States)

    Baciu, Anamaria; Ardelean, Magdalena; Pop, Aniela; Pode, Rodica; Manea, Florica

    2015-01-01

    This work reported new voltammetric/amperometric-based protocols using a commercial boron-doped diamond (BDD) electrode for simple and fast simultaneous detection of sulfide and nitrite from water. Square-wave voltammetry operated under the optimized working conditions of 0.01 V step potential, 0.5 V modulation amplitude and 10 Hz frequency allowed achieving the best electroanalytical parameters for the simultaneous detection of nitrite and sulfide. For practical in-field detection applications, the multiple-pulsed amperometry technique was operated under optimized conditions, i.e., −0.5 V/SCE for a duration of 0.3 s as conditioning step, +0.85 V/SCE for a duration of 3 s that assure the sulfide oxidation and +1.25 V/SCE for a duration of 0.3 s, where the nitrite oxidation occurred, which allowed the simultaneously detection of sulfide and nitrite without interference between them. Good accuracy was found for this protocol in comparison with standardized methods for each anion. Also, no interference effect was found for the cation and anion species, which are common in the water matrix. PMID:26102487

  14. Biosensor for laboratory and lander-based analysis of benthicnitrate plus nitrite distribution in marine environments

    DEFF Research Database (Denmark)

    Revsbech, N. P.; Glud, Ronnie Nøhr

    2009-01-01

    We present a psychotropic bacteria–based biosensor that can be used in low–temperature seawater for the analysis of nitrate + nitrite (NOx –). The sensor can be used to resolve concentrations below 1 µmol L–1 at low temperature (

  15. Nitrite-induced enhancement of toxicity of phenanthrene in fish and its implications for coastal waters

    Digital Repository Service at National Institute of Oceanography (India)

    Shailaja, M.S.; Rodrigues, A.

    , USA) added to the test tanks dissolved in dimethylformamide (0.3ml) to give a final concentration of 4.35lgl C2551 with or without the simul- taneous addition of an aqueous solution of sodium ni- trite (final concentration, 1lM nitrite). Control tanks...

  16. Reduced iron associated with secondary nitrite maxima in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Moffetta, J.W.; Goepferta, T.J.; Naqvi, S.W.A

    Dissolved iron and Fe(II) were measured in the oxygen minimum zone (OMZ) of the Arabian Sea in September 2004. The OMZ is a well-demarcated feature characterized by high rates of denitrification, and a deep nitrite maximum coinciding with oxygen...

  17. Partial nitritation ANAMMOX in submerged attached growth bioreactors with smart aeration at 20 °C.

    Science.gov (United States)

    Shannon, James M; Hauser, Lee W; Liu, Xikun; Parkin, Gene F; Mattes, Timothy E; Just, Craig L

    2015-01-01

    Submerged attached growth bioreactors (SAGBs) were operated at 20 °C for 30 weeks in smart-aerated, partial nitritation ANAMMOX mode and in a timer-controlled, cyclic aeration mode. The smart-aerated SAGBs removed 48-53% of total nitrogen (TN) compared to 45% for SAGBs with timed aeration. Low dissolved oxygen concentrations and cyclic pH patterns in the smart-aerated SAGBs suggested conditions favorable to partial nitritation ANAMMOX and stoichiometrically-derived and numerically modeled estimations attributed 63-68% and 14-44% of TN removal to partial nitritation ANAMMOX in these bioreactors, respectively. Ammonia removals of 36-67% in the smart-aerated SAGBs, with measured oxygen and organic carbon limitations, further suggest partial nitritation ANAMMOX. The smart-aerated SAGBs required substantially less aeration to achieve TN removals similar to SAGBs with timer-controlled aeration. Genomic DNA testing confirmed that the dominant ANAMMOX seed bacteria, received from a treatment plant utilizing the DEMON® sidestream deammonification process, was a Candidatus Brocadia sp. (of the Planctomycetales order). The DNA from these bacteria was also present in the SAGBs at the conclusion of the study providing evidence for attached growth and limited biomass washout.

  18. Nitrite promotes protein carbonylation and Strecker aldehyde formation in experimental fermented sausages: are both events connected?

    Science.gov (United States)

    Villaverde, A; Ventanas, J; Estévez, M

    2014-12-01

    The role played by curing agents (nitrite, ascorbate) on protein oxidation and Strecker aldehyde formation is studied. To fulfill this objective, increasing concentrations of nitrite (0, 75 and 150ppm) and ascorbate (0, 250 and 500ppm) were added to sausages subjected to a 54day drying process. The concurrence of intense proteolysis, protein carbonylation and formation of Strecker aldehydes during processing of sausages suggests that α-aminoadipic semialdehyde (AAS) and γ-glutamic semialdehyde (GGS) may be implicated in the formation of Strecker aldehydes. The fact that nitrite (150ppm, ingoing amount) significantly promoted the formation of protein carbonyls at early stages of processing and the subsequent formation of Strecker aldehydes provides strength to this hypothesis. Ascorbate (125 and 250ppm) controlled the overall extent of protein carbonylation in sausages without declining the formation of Strecker aldehydes. These results may contribute to understanding the chemistry fundamentals of the positive influence of nitrite on the flavor and overall acceptability of cured muscle foods.

  19. [Research on Cultivation and Stability of Nitritation Granular Sludge in Integrated ABR-CSTR Reactor].

    Science.gov (United States)

    Wu, Kai-cheng; Wu, Peng; Shen, Yao-liang; Li, Yue-han; Wang, Han-fang; Xu, Yue-zhong

    2015-11-01

    Abstract: The last two compartments of the Anaerobic Baffled Readtor ( ABR) were altered into aeration tank and sedimentation tank respectively to get an integrated anaerobic-aerobic reactor, using anaerobic granular sludge in anaerobic zone and aerobic granular sludge in aerobic zone as seed sludge. The research explored the condition to cultivate nitritation granular sludge, under the condition of continuous flow. The C/N rate was decreased from 1 to 0.4 and the ammonia nitrogen volumetric loading rate was increased from 0.89 kg x ( m3 x d)(-1) to 2.23 kg x (m3 x d)(-1) while the setting time of 1 h was controlled in the aerobic zone. After the system was operated for 45 days, the mature nitritation granular sludge in aerobic zone showed a compact structure and yellow color while the nitrite accumulation rate was about 80% in the effluent. The associated inhibition of free ammonia (FA) and free nitrous acid (FNA) dominated the nitritation. Part of granules lost stability during the initial period of operation and flocs appeared in the aerobic zone. However, the flocs were transformed into newly generated small particles in the following reactor operation, demonstrating that organic carbon was benefit to granulation and the enrichment of slow-growing nitrifying played an important role in the stability of granules.

  20. Using saliva nitrite and nitrate levels as a biomarker for drug induced gingival overgrowth

    Directory of Open Access Journals (Sweden)

    Erkan eSukuroglu

    2015-12-01

    Full Text Available Aim: Drug-induced gingival overgrowth has a multifactorial nature and the pathogenesis is still uncertain. It has been suggested that Nitric Oxide (NO might play a role in the pathogenesis of drug-induced gingival overgrowth due to the contribution of NO to immune response and matrix degradation. NO levels in biological fluids have been used as a diagnostic biomarker in many diseases. The aim of this study is to determine whether NO levels in plasma, saliva and gingival crevicular fluid (GCF can serve as a potential biomarker for the evaluation of drug-induced gingival overgrowth risk. Material and Methods: A total of 104 patients, receiving cyclosporine A (n=35, phenytoin (n=25, nifedipine (n=26 or diltiazem (n=18 participated in the study. The amount of gingival overgrowth was evaluated with two indices and was given as percentage. Periodontal clinical parameters including plaque index (PI, gingival index (GI, gingival bleeding time index (GBTI and probing depth (PD were also assessed. Saliva, GCF and plasma samples were obtained from each participants. Nitrite and nitrate levels in saliva, GCF and plasma were analyzed by Griess reagent. Results: Salivary nitrite and nitrate levels in responders were significantly higher than those in non-responders in only phenytoin group (p˂0.05. Nitrite and nitrate levels of gingival crevicular fluid and plasma did not significantly differ between responders and non-responders in all study groups (p˃0.05. Salivary nitrite levels exhibited a significant correlation with PD, GBTI, severity of gingival overgrowth (%GO and GCF volume (p˂0.05. Additionally, a strong positive correlation was detected between saliva and plasma nitrate levels (p˂0.005. However, both nitrite and nitrate levels in GCF and plasma demonstrated no significant correlation with clinical parameters, GO severity and GCF volume (p˃0.05.Conclusion: Salivary nitrite and nitrate levels could be used as periodontal disease biomarkers in

  1. Tolerance of ciliated protozoan Paramecium bursaria (Protozoa,Ciliophora) to ammonia and nitrites

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The tolerance to ammonia and nitrites in freshwater ciliate Paramecium bursaria was measured in a conventional open system. The ciliate was exposed to different concentrations of ammonia and nitrites for 2h and 12h in order to determine the lethal concentrations. Linear regression analysis revealed that the 2h-LC50 value for ammonia was 95.94 mg/L and for nitrite 27.35 mg/L using probit scale method (with 95% confidence intervals). There was a linear correlation between the mortality probit scale and logarithmic concentration of ammonia which fit by a regression equation y=7.32x-9.51 (R2=0.98; y, mortality probit scale; x, logarithmic concentration of ammonia), by which 2 h-LC50 value for ammonia was fotnd to be 95.50 mg/L. A linear correlation between mortality probit scales and logarithmic concentration of nitrite is also followed the regression equation y=2.86x+0.89 (R2=0.95; y, mortality probit scale; x, logarithmic concentration of nitrite). The regression analysis of toxicity curves showed that the linear correlation between exposed time of ammonia-N LC50 value and ammonia-N LC50 value followed the regression equation y=2862.85e-0.0ax (R2=0.95; y, duration of exposure to LC50 value; x, LC50 value), and that between exposed time of nitrite-N LC50 value and nitrite-N LC50 value followed the regression equation y = 127.15e-0.13x (R2=0.91; y, exposed time of LC50 value; x, LC50 value). The results demonstrate that the tolerance to ammonia in P. bursaria is considerably higher than that of the larvae or juveniles of some metozoa, e.g. cultured prawns and oysters. In addition, ciliates, as bacterial predators, are likely to play a positive role in maintaining and improving water quality in aquatic environments with high-level ammonium, such as sewage treatment systems.

  2. The genome of Nitrospina gracilis illuminates the metabolism and evolution of the major marine nitrite oxidizer

    Directory of Open Access Journals (Sweden)

    Sebastian eLuecker

    2013-02-01

    Full Text Available In marine systems, nitrate is the major reservoir of inorganic fixed nitrogen. The only known biological nitrate-forming reaction is nitrite oxidation, but despite its importance, our knowledge of the organisms catalyzing this key process in the marine N-cycle is very limited. The most frequently encountered marine NOB are related to Nitrospina gracilis, an aerobic chemolithoautotrophic bacterium isolated from ocean surface waters. To date, limited physiological and genomic data for this organism were available and its phylogenetic affiliation was uncertain. In this study, the draft genome sequence of Nitrospina gracilis strain 3/211 was obtained. Unexpectedly for an aerobic organism, N. gracilis lacks classical reactive oxygen defense mechanisms and uses the reductive tricarboxylic acid cycle for carbon fixation. These features indicate microaerophilic ancestry and are consistent with the presence of Nitrospina in marine oxygen minimum zones. Fixed carbon is stored intracellularly as glycogen, but genes for utilizing external organic carbon sources were not identified. N. gracilis also contains a full gene set for oxidative phosphorylation with oxygen as terminal electron acceptor and for reverse electron transport from nitrite to NADH. A novel variation of complex I may catalyze the required reverse electron flow to low-potential ferredoxin. Interestingly, comparative genomics indicated a strong evolutionary link between Nitrospina, the nitrite-oxidizing genus Nitrospira, and anaerobic ammonium oxidizers, apparently including the horizontal transfer of a periplasmically oriented nitrite oxidoreductase and other key genes for nitrite oxidation at an early evolutionary stage. Further, detailed phylogenetic analyses using concatenated marker genes provided evidence that Nitrospina forms a novel bacterial phylum, for which we propose the name Nitrospinae.

  3. The Genome of Nitrospina gracilis Illuminates the Metabolism and Evolution of the Major Marine Nitrite Oxidizer.

    Science.gov (United States)

    Lücker, Sebastian; Nowka, Boris; Rattei, Thomas; Spieck, Eva; Daims, Holger

    2013-01-01

    In marine systems, nitrate is the major reservoir of inorganic fixed nitrogen. The only known biological nitrate-forming reaction is nitrite oxidation, but despite its importance, our knowledge of the organisms catalyzing this key process in the marine N-cycle is very limited. The most frequently encountered marine NOB are related to Nitrospina gracilis, an aerobic chemolithoautotrophic bacterium isolated from ocean surface waters. To date, limited physiological and genomic data for this organism were available and its phylogenetic affiliation was uncertain. In this study, the draft genome sequence of N. gracilis strain 3/211 was obtained. Unexpectedly for an aerobic organism, N. gracilis lacks classical reactive oxygen defense mechanisms and uses the reductive tricarboxylic acid cycle for carbon fixation. These features indicate microaerophilic ancestry and are consistent with the presence of Nitrospina in marine oxygen minimum zones. Fixed carbon is stored intracellularly as glycogen, but genes for utilizing external organic carbon sources were not identified. N. gracilis also contains a full gene set for oxidative phosphorylation with oxygen as terminal electron acceptor and for reverse electron transport from nitrite to NADH. A novel variation of complex I may catalyze the required reverse electron flow to low-potential ferredoxin. Interestingly, comparative genomics indicated a strong evolutionary link between Nitrospina, the nitrite-oxidizing genus Nitrospira, and anaerobic ammonium oxidizers, apparently including the horizontal transfer of a periplasmically oriented nitrite oxidoreductase and other key genes for nitrite oxidation at an early evolutionary stage. Further, detailed phylogenetic analyses using concatenated marker genes provided evidence that Nitrospina forms a novel bacterial phylum, for which we propose the name Nitrospinae.

  4. Genome sequence of the chemolithoautotrophic nitrite-oxidizing bacterium Nitrobacter winogradskyi Nb-255

    Energy Technology Data Exchange (ETDEWEB)

    Hauser, Loren John [ORNL; Land, Miriam L [ORNL; Larimer, Frank W [ORNL; Arp, D J [Oregon State University; Hickey, W J [University of Wisconsin, Madison

    2006-03-01

    The alphaproteobacterium Nitrobacter winogradskyi (ATCC 25391) is a gram-negative facultative chemolithoautotroph capable of extracting energy from the oxidation of nitrite to nitrate. Sequencing and analysis of its genome revealed a single circular chromosome of 3,402,093 bp encoding 3,143 predicted proteins. There were extensive similarities to genes in two alphaproteobacteria, Bradyrhizobium japonicum USDA110 (1,300 genes) and Rhodopseudomonas palustris CGA009 CG (815 genes). Genes encoding pathways for known modes of chemolithotrophic and chemoorganotrophic growth were identified. Genes encoding multiple enzymes involved in anapleurotic reactions centered on C2 to C4 metabolism, including a glyoxylate bypass, were annotated. The inability of N. winogradskyi to grow on C6 molecules is consistent with the genome sequence, which lacks genes for complete Embden-Meyerhof and Entner-Doudoroff pathways, and active uptake of sugars. Two gene copies of the nitrite oxidoreductase, type I ribulose-1,5-bisphosphate carboxylase/oxygenase, cytochrome c oxidase, and gene homologs encoding an aerobic-type carbon monoxide dehydrogenase were present. Similarity of nitrite oxidoreductases to respiratory nitrate reductases was confirmed. Approximately 10% of the N. winogradskyi genome codes for genes involved in transport and secretion, including the presence of transporters for various organic-nitrogen molecules. The N. winogradskyi genome provides new insight into the phylogenetic identity and physiological capabilities of nitrite-oxidizing bacteria. The genome will serve as a model to study the cellular and molecular processes that control nitrite oxidation and its interaction with other nitrogen-cycling processes.

  5. Electrocatalytic reduction of nitrite on tetraruthenated metalloporphyrins/Nafion glassy carbon modified electrode

    Energy Technology Data Exchange (ETDEWEB)

    Calfuman, Karla [Facultad de Ciencias, Departamento de Quimica, Universidad de Chile, Las Palmeras 3425, Casilla 653, Nunoa, Santiago (Chile); Aguirre, Maria Jesus [Facultad de Quimica y Biologia, Departamento de Quimica de los Materiales, Universidad de Santiago de Chile, Santiago (Chile); Canete-Rosales, Paulina; Bollo, Soledad [Facultad de Ciencias Quimicas y Farmaceuticas, Departamento de Quimica Farmacologica y Toxicologica, Universidad de Chile, Santiago (Chile); Llusar, Rosa [Departamento de Quimica Fisica y Analitica, Universidad de Jaume I, Castellon (Spain); Isaacs, Mauricio, E-mail: misaacs@uchile.cl [Facultad de Ciencias, Departamento de Quimica, Universidad de Chile, Las Palmeras 3425, Casilla 653, Nunoa, Santiago (Chile)

    2011-10-01

    Highlights: > Preparation and characterization of modified electrodes with M(II) Tetraruthenated porphyrins onto a Nafion film. > The electrodes were characterized by SEM, TEM, AFM and SECM techniques. > The modified electrodes are active in the electrochemical reduction of nitrite at -660 mV vs Ag/AgCl. > GC/Nf/CoTRP modified electrode is more electrochemically active than their Ni and Zn analogues. - Abstract: This paper describes the electrochemical reduction of nitrite ion in neutral aqueous solution mediated by tetraruthenated metalloporphyrins (Co(II), Ni(II) and Zn(II)) electrostatically assembled onto a Nafion film previously adsorbed on glassy carbon or ITO electrodes. Scanning electron microscope (SEM-EDX) and transmission electron microscopy (TEM) results have shown that on ITO electrodes the macrocycles forms multiple layers with a disordered stacking orientation over the Nafion film occupying hydrophobic and hydrophilic sites in the polyelectrolyte. Atomic force microscopy (AFM) results demonstrated that the Nafion film is 35 nm thick and tetraruthenated metalloporphyrins layers 190 nm thick presenting a thin but compacted morphology. Scanning electrochemical microscopy (SECM) images shows that the Co(II) tetraruthenated porphyrins/Nf/GC modified electrode is more electrochemically active than their Ni and Zn analogues. These modified electrodes are able to reduce nitrite at -660 mV showing enhanced reduction current and a decrease in the required overpotential compared to bare glassy carbon electrode. Controlled potential electrolysis experiments verify the production of ammonia, hydrazine and hydroxylamine at potentials where reduction of solvent is plausible demonstrating some selectivity toward the nitrite ion. Rotating disc electrode voltammetry shows that the factor that governs the kinetics of nitrite reduction is the charge propagation in the film.

  6. Kinetic Constants for Biological Ammonium and Nitrite Oxidation Processes Under Sulfide Inhibition.

    Science.gov (United States)

    Bejarano-Ortiz, Diego Iván; Huerta-Ochoa, Sergio; Thalasso, Frédéric; Cuervo-López, Flor de María; Texier, Anne-Claire

    2015-12-01

    Inhibition of nitrification by sulfide was assessed using sludge obtained from a steady-state nitrifying reactor. Independent batch activity assays were performed with ammonium and nitrite as substrate, in order to discriminate the effect of sulfide on ammonium and nitrite oxidation. In the absence of sulfide, substrate affinity constants (K S,NH4  = 2.41 ± 0.11 mg N/L; K s, NO2  = 0.74 ± 0.03 mg N/L) and maximum specific rates (q max,NH4  = 0.086 ± 0.008 mg N/mg microbial protein h; q max,NO2  = 0.124 ± 0.001 mg N/mg microbial protein h) were determined. Inhibition of ammonium oxidation was no-competitive (inhibition constant (K i , NH4 ) of 2.54 ± 0.12 mg HS(-)-S/L) while inhibition of nitrite oxidation was mixed (competitive inhibition constant (K' i , NO2 ) of 0.22 ± 0.03 mg HS(-)-S/L and no-competitive inhibition constant (K i , NO2 ) of 1.03 ± 0.06 mg HS(-)-S/L). Sulfide has greater inhibitory effect on nitrite oxidation than ammonium oxidation, and its presence in nitrification systems should be avoided to prevent accumulation of nitrite. By simulating the effect of sulfide addition in a continuous nitrifying reactor under steady-state operation, it was shown that the maximum sulfide concentration that the sludge can tolerate without affecting the ammonium consumption efficiency and nitrate yield is 1 mg HS(-)-S/L.

  7. Combined exposure to ambient UVB radiation and nitrite negatively affects survival of amphibian early life stages

    Energy Technology Data Exchange (ETDEWEB)

    Macias, Guadalupe [Donana Biological Station, CSIC, Spanish Council for Scientific Research. P.O. Box 1056, Sevilla 41013 (Spain); Marco, Adolfo [Donana Biological Station, CSIC, Spanish Council for Scientific Research. P.O. Box 1056, Sevilla 41013 (Spain)], E-mail: amarco@ebd.csic.es; Blaustein, Andrew R. [Department of Zoology, Oregon State University, Corvallis, Oregon, 97331 (United States)

    2007-10-15

    Many aquatic species are sensitive to ambient levels of ultraviolet-B radiation (UVB) and chemical fertilizers. However, recent studies indicate that the interaction among multiple stressors acting simultaneously could be contributing to the population declines of some animal species. Therefore, we tested the potential synergistic effects between ambient levels of UVB and a contaminant, sodium nitrite in the larvae of two amphibian species, the common European toad Bufo bufo and the Iberian green frog Rana perezi. We studied R. perezi from both mountain and coastal populations to examine if populations of the same species varied in their response to stressors in different habitats. Both species were sensitive to the two stressors acting alone, but the interaction between the two stressors caused a multiplicative impact on tadpole survival. For B. bufo, the combination of UVB and nitrite was up to seven times more lethal than mortality for each stressor alone. In a coastal wetland, the combination of UVB and nitrite was four times more toxic for R. perezi than the sum of the effect on mortality for each stressor alone. One mg/L of nitrite killed half the population of R. perezi at Gredos Mountains at day 10 in the absence of UVB. In the presence of UVB, 50% of the tadpoles from the same experiment died at day 7. Similar toxic response were found for R. perezi in two highly contrasted environments suggesting this synergistic interaction can be a widespread phenomenon. The interaction of excess chemical fertilizers and manure with ambient UVB radiation could be contributing to the global decline of some amphibian species. We suggest that potential exposure to UVB radiation be accounted for when assessing water quality criteria regarding nitrite pollution.

  8. Dietary Nitrates, Nitrites, and Nitrosamines Intake and the Risk of Gastric Cancer: A Meta-Analysis

    Directory of Open Access Journals (Sweden)

    Peng Song

    2015-12-01

    Full Text Available The potential associations between dietary consumption of nitrates, nitrites, and nitrosamines and gastric cancer risk have been investigated by several studies, but yielded inconclusive results. We conducted a meta-analysis to provide a quantitative assessment of their relationships. Relevant articles were identified by a systematic literature searching of PubMed and Embase databases prior to August 2015. Random-effects models were employed to pool the relative risks. A total of 22 articles consisting of 49 studies—19 studies for nitrates, 19 studies for nitrites, and 11 studies for N-nitrosodimethylamine (NDMA—were included. The summary relative risk of stomach cancer for the highest categories, compared with the lowest, was 0.80 (95% confidence interval (CI, 0.69–0.93 for dietary nitrates intake, 1.31 (95% CI, 1.13–1.52 for nitrites, and 1.34 (95% CI, 1.02–1.76 for NDMA (p for heterogeneity was 0.015, 0.013 and <0.001, respectively. The study type was found as the main source of heterogeneity for nitrates and nitrites. The heterogeneity for NDMA could not be eliminated completely through stratified analysis. Although significant associations were all observed in case-control studies, the cohort studies still showed a slight trend. The dose-response analysis indicated similar results as well. High nitrates intake was associated with a weak but statistically significant reduced risk of gastric cancer. Whereas increased consumption of nitrites and NDMA seemed to be risk factors for cancer. Due to the lack of uniformity for exposure assessment across studies, further prospective researches are warranted to verify these findings.

  9. Survery of nitrate and nitrite content in distributed red meat in Mazandaran (2008

    Directory of Open Access Journals (Sweden)

    Laleh Karimzadeh

    2009-01-01

    Full Text Available , , , , , 1 2 3 (Received 28 September, 2009 ; Accepted 28 December, 2009AbstractBackground and purpose: Chemical fertilizers which contain nitrite and nitrate ions contaminate water, soil and plants. The livestock are exposed to the ions through grazing in these areas. This study was designed to evaluate the levels of ions in raw sheep and cows meat in Mazandaran and also, to estimate the dietary intake of the ions from fresh meat consumed in a regular diet.Materials and methods: A total of 36 samples of beef and 36 samples of mutton meat were collected from different cities of Mazandaran province (Sari, Babol and Qaemshahr and their nitrite and nitrate contents were measured by colorimetric Griess Ilosvay method. Data were statistically analyzed by using Mann Whitney.Results: The mean of nitrate and nitrite in mutton was 4/9 and 0/36 and beef was 6/3 and 0/38 mg/kg. Nitrite and nitrate content in beef and mutton had no significant difference.Conclusion: Considering the recommended consumption of meat groups and their substitutes in the food pyramid, which is 6.5 ounce/daily for those who use 2,500 Kcal/day, it is estimated that the amount of nitrate and nitrite consumed by an adult in all meat groups from red meat, the nitrate intake is higher than in some countries such as the UK, although lower than CONTAM Panel is recommended. J Mazand Univ Med Sci 2009; 19(72: 35-41 (Persian.

  10. Impact of hemoglobin nitrite to nitric oxide reductase on blood transfusion for resuscitation from hemorrhagic shock

    Directory of Open Access Journals (Sweden)

    Chad Brouse

    2015-01-01

    Full Text Available Background: Transfusion of blood remains the gold standard for fluid resuscitation from hemorrhagic shock. Hemoglobin (Hb within the red blood cell transports oxygen and modulates nitric oxide (NO through NO scavenging and nitrite reductase. Aims: This study was designed to examine the effects of incorporating a novel NO modulator, RRx-001, on systemic and microvascular hemodynamic response after blood transfusion for resuscitation from hemorrhagic shock in a hamster window chamber model. In addition, to RRx-001 the role of low dose of nitrite (1 × 10−9 moles per animal supplementation after resuscitation was studied. Materials and Methods: Severe hemorrhage was induced by arterial controlled bleeding of 50% of the blood volume (BV and the hypovolemic state was maintained for 1 h. The animals received volume resuscitation by an infusion of 25% of BV using fresh blood alone or with added nitrite, or fresh blood treated with RRx-001 (140 mg/kg or RRx-001 (140 mg/kg with added nitrite. Systemic and microvascular hemodynamics were followed at baseline and at different time points during the entire study. Tissue apoptosis and necrosis were measured 8 h after resuscitation to correlate hemodynamic changes with tissue viability. Results: Compared to resuscitation with blood alone, blood treated with RRx-001 decreased vascular resistance, increased blood flow and functional capillary density immediately after resuscitation and preserved tissue viability. Furthermore, in RRx-001 treated animals, both mean arterial pressure (MAP and met Hb were maintained within normal levels after resuscitation (MAP >90 mmHg and metHb <2%. The addition of nitrite to RRx-001 did not significantly improve the effects of RRx-001, as it increased methemoglobinemia and lower MAP. Conclusion: RRx-001 alone enhanced perfusion and reduced tissue damage as compared to blood; it may serve as an adjunct therapy to the current gold standard treatment for resuscitation from

  11. Levels of Nitrates and Nitrites in Chili Pepper and Ventricina Salami

    Science.gov (United States)

    Piccirilli, Michele; Iafigliola, Luigi; Amadoro, Carmela

    2014-01-01

    Ventricina is a traditional sausage made from pork meat produced in the Abruzzi and Molise regions. The aim of this study was to detect the content of nitrates and nitrites in local cultivars of chilli pepper, and their concentration in ventricina samples spiced with the same chilli pepper. Furthermore, it was examined whether, in the samples of ventricina with nitrate addition, the spicing with chilli pepper could exceed the maximum added dose. The concentration of nitrates and nitrites in the organic chilli pepper was 531.0±94.6 mg/kg and less than 5.0 mg, respectively, in the traditional chilli pepper it was 394.0±39.6 and less than 5.0 mg, while in the commercial it was 325.0±115.0 and less than 5.0 mg. The determination of nitrites and nitrates was carried out by high performance ion chromatography. In ventricina samples produced without added sodium nitrate, nitrates and nitrites were below 5.0 mg/kg at the case-filling time (t0) and after 50 days of aging (t50). In the samples of ventricina with added sodium nitrate, nitrate concentration values were 134.0±20.9 mg/kg at t0 and 129.0±15.4 mg/kg at t50, while the nitrites were below 5.0 mg/kg at t0 and 28.8±15.8 mg/kg at t50. Although in ventricina the amount of chilli pepper is quite relevant, it did not lead to a detectable concentration of nitrates. The maximum allowed amount was never exceeded.

  12. PENURUNAN KADAR AMONIA, NITRIT, DAN NITRAT LIMBAH CAIR INDUSTRI TAHU MENGGUNAKAN ARANG AKTIF DARI AMPAS KOPI

    Directory of Open Access Journals (Sweden)

    Irmanto

    2009-11-01

    Full Text Available The tofu industry is one of food industry which the product of organic waste to environment pollution. One of alternative methode which used to overcome tofu industrial waste water pollution is adsorption methode using activated carbon from coffee waste. The aim of this researched is to know about the activated carbon from coffee waste quality which observe of rendemen, water content, ash content, and iodium adsorption, to know optimum contact of time and pH of coffee waste to decrease ammonia, nitrite and nitrate contents in tofu industry waste water and to know decrease percentage of ammonia, nitrite and nitrate contents in tofu industrial waste water using activated carbon from coffee waste. The activated carbon made by soaking of coffee waste in HCl 0.1 M solution for 2 days. The activated carbon coaled in muffle furnace at temperature 350°C. The activated carbon analyzed consist of rendemen, water content, ash content, and iodium adsorption. Optimum contact of time and pH of coffee waste determined in order to get optimum adsorption ammonia, nitrite and nitrate in tofu industrial waste water. Contact time variation are 1, 10, 30, 45, 60, 90, 120 minutes and pH variation are 4, 5, 6, 7, 8, 9, 10. The result showed that the activated carbon from coffee waste fulfill the criteria SNI number 06-3730-1995. The activated carbon from coffee waste could be used to decrease the ammonia, nitrite, and nitrate contents in tofu industrial waste water at the optimum contact of time of 30 minutes and pH 7. Decreasing percentage of ammonia, nitrite and nitrate contents in tofu industrial waste water are 64,69% , 52,35% and 86,40% respectively.

  13. NEW TRENDS IN AMMONIA NITROGEN REMOVAL FROM WASTEWATER: NITRITATION – ANAMMOX AT LOW TEMPERATURE

    Directory of Open Access Journals (Sweden)

    Mariusz Tomaszewski

    2017-04-01

    Full Text Available Partial nitrification (nitritation – anammox (anaerobic ammonia oxidation process is increasingly used to treat wastewater, characterized by a high nitrogen content and high temperature (25 - 40°C. It is connected with the optimal temperature of anammox bacteria, which is at the range between 30 and 40°C. Mainstream application of anammox for the municipal wastewater, characterized by lower temperature seems to be one of the most challenging, but profitable process. Thenceforth, the research performed in the field of the nitritation – anammox at low temperature (10 - 20°C become more and more intense. Compared with the conventional nitrification – denitrification system, nitritation – anammox reduces oxygen demand, eliminates the need for organic carbon source and produces less excess sludge. As a result, it allows to a significant cost reduction. This paper reviews the most important and recent information in the field of nitritation – anammox process at low temperature. Effective nitrogen removal from the municipal wastewater was demonstrated at 15°C in a pilot scale and at 12°C in a laboratory scale reactor. The best performance is achieved in sequencing batch reactors and moving bed reactors with biofilm or granular biomass, as well as combinations of these technologies. Molecular biology studies shows that anammox bacteria of the genus Candidatus Brocadia may have the biggest predispositions to adapt to low temperature. However, temperature about 10°C, time and method of biomass adaptation are still the main challenges for stable and common nitritation – anammox process.

  14. Oxidative stress and nitrite dynamics under maximal load in elite athletes: relation to sport type.

    Science.gov (United States)

    Cubrilo, Dejan; Djordjevic, Dusica; Zivkovic, Vladimir; Djuric, Dragan; Blagojevic, Dusko; Spasic, Mihajlo; Jakovljevic, Vladimir

    2011-09-01

    Maximal workload in elite athletes induces increased generation of reactive oxygen/nitrogen species (RONS) and oxidative stress, but the dynamics of RONS production are not fully explored. The aim of our study was to examine the effects of long-term engagement in sports with different energy requirements (aerobic, anaerobic, and aerobic/anaerobic) on oxidative stress parameters during progressive exercise test. Concentrations of lactates, nitric oxide (NO) measured through stabile end product-nitrites (NO(2) (-)), superoxide anion radical (O(2) (•-)), and thiobarbituric reactive substances (TBARS) as index of lipid peroxidation were determined in rest, after maximal workload, and at 4 and 10th min of recovery in blood plasma of top level competitors in rowing, cycling, and taekwondo. Results showed that sportmen had similar concentrations of lactates and O(2) (•-) in rest. Nitrite concentrations in rest were the lowest in taekwondo fighters, while rowers had the highest levels among examined groups. The order of magnitude for TBARS level in the rest was bicycling > taekwondo > rowing. During exercise at maximal intensity, the concentration of lactate significantly elevated to similar levels in all tested sportsmen and they were persistently elevated during recovery period of 4 and 10 min. There were no significant changes in O(2) (•-), nitrite, and TBARS levels neither at the maximum intensity of exercise nor during the recovery period comparing to the rest period in examined individuals. Our results showed that long term different training strategies establish different basal nitrites and lipid peroxidation levels in sportmen. However, progressive exercise does not influence basal nitrite and oxidative stress parameters level neither at maximal load nor during the first 10 min of recovery in sportmen studied.

  15. Stable Copper-Nitrosyl Formation By Nitrite Reductase in Either Oxidation State

    Energy Technology Data Exchange (ETDEWEB)

    Tocheva, E.I.; Rosell, F.I.; Mauk, A.G.; Murphy, M.E.P.

    2009-06-04

    Nitrite reductase (NiR) is an enzyme that uses type 1 and type 2 copper sites to reduce nitrite to nitric oxide during bacterial denitrification. A copper-nitrosyl intermediate is a proposed, yet poorly characterized feature of the NiR catalytic cycle. This intermediate is formally described as Cu(I)-NO{sup +} and is proposed to be formed at the type 2 copper site after nitrite binding and electron transfer from the type 1 copper site. In this study, copper-nitrosyl complexes were formed by prolonged exposure of exogenous NO to crystals of wild-type and two variant forms of NiR from Alcaligenes faecalis (AfNiR), and the structures were determined to 1.8 {angstrom} or better resolution. Exposing oxidized wild-type crystals to NO results in the reverse reaction and formation of nitrite that remains bound at the active site. In a type 1 copper site mutant (H145A) that is incapable of electron transfer to the type 2 site, the reverse reaction is not observed. Instead, in both oxidized and reduced H145A crystals, NO is observed bound in a side-on manner to the type 2 copper. In AfNiR, Asp98 forms hydrogen bonds to both substrate and product bound to the type 2 Cu. In the D98N variant, NO is bound side-on but is more disordered when observed for the wild-type enzyme. The solution EPR spectra of the crystallographically characterized NiR-NO complexes indicate the presence of an oxidized type 2 copper site and thus are interpreted as resulting from stable copper-nitrosyls and formally assigned as Cu(II)-NO{sup -}. A reaction scheme in which a second NO molecule is oxidized to nitrite can account for the formation of a CuD-NO{sup -} species after exposure of the oxidized H145A variant to NO gas.

  16. Nitrites in induced sputum as a simple and cheap non-invasive marker of airway inflammation for asthmatic schoolchildren.

    Science.gov (United States)

    Recabarren, Arturo; Apaza, Carlos; Castro-Rodríguez, José A

    2008-08-01

    To determine if there are differences in the nitric oxide metabolites (nitrites) in sputum of patients with persistent asthma and healthy schoolchildren, we performed a case-control study in a tertiary care hospital in Arequipa, Perú. Nitrites in induced sputum samples were measured using the Griess assay in 30 persistent asthmatics (mean age of 10.1 yr) and 30 controls (mean age of 11.9 yr). The mean +/- s.d. of nitrites among asthmatics was significantly higher than the controls (16.30 +/- 8.6 vs. 10.25 +/- 4.68 nmol/ml, respectively, p = 0.001). Moreover, the nitrite level in the sputum in children with severe persistent asthma was higher than in the level found in the moderate and mild asthmatics (32.83 +/- 9.48 vs. 18.10 +/- 1.96 vs. 11.84 +/- 4.73 nmol/ml, respectively, p < 0.01 for linear trend). This study showed for the first time in children that asthmatics have significantly higher levels of nitrites in induced sputum than healthy controls and that the level of nitrite correlates with the severity of the asthma. Nitrite levels in sputum, a simple and cheap, non-invasive method, may be a good alternative to measure the severity of inflammation in asthmatic children.

  17. Effect of alkalinity on nitrite accumulation in treatment of coal chemical industry wastewater using moving bed biofilm reactor.

    Science.gov (United States)

    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.

  18. Electron paramagnetic resonance spectroscopic investigation of the inhibition of the phosphoroclastic system of Clostridium sporogenes by nitrite.

    Science.gov (United States)

    Payne, M J; Woods, L F; Gibbs, P; Cammack, R

    1990-10-01

    The proposal that nitrite exerts its inhibitory effect on anaerobic bacteria by direct interaction with the iron-sulphur proteins of the phosphoroclastic system was investigated. The effects of nitrate, nitrite with or without ascorbate, and nitric oxide on the growth of Clostridium sporogenes in liquid cultures at pH 7.4, on the rates of hydrogen production, and on the activities of the enzymes pyruvate-ferredoxin oxidoreductase and hydrogenase, and of ferredoxin were investigated. In agreement with previous studies, nitrate was the least effective inhibitor of cell growth, and nitric oxide the most effective. Nitrite reductase activity was very low in C. sporogenes, indicating that the presence of external reducing agents would be necessary for the reduction of nitrite to nitric oxide. Inhibition by nitrite was enhanced by ascorbate; 0.5 mM-nitrite with 10 mM-ascorbate stopped growth completely. In partially-purified preparations 4.1 mM-NaNO2 and equimolar ascorbate caused complete inactivation of hydrogenase activity but only partial (up to 78%) inactivation of pyruvate-ferredoxin oxidoreductase. This agreed with the loss of hydrogen production observed with nitrite in vivo. Inhibition occurred within 5 min, and was irreversible in each case. Electron paramagnetic resonance (EPR) spectroscopy showed that paramagnetic [Fe(NO)2(SR)2] species were formed during growth in the presence of nitrite, and were associated with cells. However, the intensity of these EPR signals did not correlate with the inhibition of cell growth. The [4Fe-4S] clusters in ferredoxin were shown by EPR spectroscopy to be resistant to treatment with 3.6 mM-NaNO2 and 3.6 mM-ascorbate. It is concluded that the effects of nitrite on pre-formed iron-sulphur proteins are not convincing as a basis for the lethal effects on bacterial cells.

  19. Nitrate-nitrite-nitrosamines exposure and the risk of type 1 diabetes: A review of current data.

    Science.gov (United States)

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

    2016-10-15

    The potential toxic effects of nitrate-nitrite-nitrosamine on pancreatic β cell have remained a controversial issue over the past two decades. In this study, we reviewed epidemiological studies investigated the associations between nitrate-nitrite-nitrosamines exposure, from both diet and drinking water to ascertain whether these compounds may contribute to development of type 1 diabetes. To identify relevant studies, a systematic search strategy of PubMed, Scopus, and Science Direct was conducted using queries including the key words "nitrate", "nitrite", "nitrosamine" with "type 1 diabetes" or "insulin dependent diabetes mellitus". All searches were limited to studies published in English. Ecologic surveys, case-control and cohort studies have indicated conflicting results in relation to nitrate-nitrite exposure from drinking water and the risk of type 1 diabetes. A null, sometimes even negative association has been mainly reported in regions with a mean nitrate levels water, while increased risk of type 1 diabetes was observed in those with a maximum nitrate levels > 40-80 mg/L. Limited data are available regarding the potential diabetogenic effect of nitrite from drinking water, although there is evidence indicating dietary nitrite could be a risk factor for development of type 1 diabetes, an effect however that seems to be significant in a higher range of acceptable limit for nitrate/nitrite. Current data regarding dietary exposure of nitrosamine and development of type 1 diabetes is also inconsistent. Considering to an increasing trend of type 1 diabetes mellitus (T1DM) along with an elevated nitrate-nitrite exposure, additional research is critical to clarify potential harmful effects of nitrate-nitrite-nitrosamine exposure on β-cell autoimmunity and the risk of T1DM.

  20. Nutritional epidemiology in the context of nitric oxide biology: a risk-benefit evaluation for dietary nitrite and nitrate.

    Science.gov (United States)

    Milkowski, Andrew; Garg, Harsha K; Coughlin, James R; Bryan, Nathan S

    2010-02-15

    The discovery of the nitric oxide (NO) pathway in the 1980s represented a critical advance in understanding cardiovascular disease, and today a number of human diseases are characterized by NO insufficiency. In the interim, recent biomedical research has demonstrated that NO can be modulated by the diet independent of its enzymatic synthesis from l-arginine, e.g., the consumption of nitrite- and nitrate-rich foods such as fruits, leafy vegetables, and cured meats along with antioxidants. Regular intake of nitrate-containing food such as green leafy vegetables may ensure that blood and tissue levels of nitrite and NO pools are maintained at a level sufficient to compensate for any disturbances in endogenous NO synthesis. However, some in the public perceive that dietary sources of nitrite and nitrate are harmful, and some epidemiological studies reveal a weak association between foods that contain nitrite and nitrate, namely cured and processed meats, and cancer. This paradigm needs revisiting in the face of undisputed health benefits of nitrite- and nitrate-enriched diets. This review will address and interpret the epidemiological data and discuss the risk-benefit evaluation of dietary nitrite and nitrate in the context of nitric oxide biology. The weak and inconclusive data on the cancer risk of nitrite, nitrate and processed meats are far outweighed by the health benefits of restoring NO homeostasis via dietary nitrite and nitrate. This risk/benefit balance should be a strong consideration before there are any suggestions for new regulatory or public health guidelines for dietary nitrite and nitrate exposures.

  1. The Research Status of Nitrite Safety%亚硝酸盐安全性研究现状

    Institute of Scientific and Technical Information of China (English)

    姚骏; 陈闯; 佟永薇

    2015-01-01

    This paper focused on the safety of nitrite. The research status of nitrite alternatives and the inhibition of N-nitrosamine were reviewed, which would provide a reference of the nitrite safer using in cured meat.%从亚硝酸盐的安全性入手,对亚硝酸盐替代物研究现状和抑制N-亚硝胺生成研究现状进行综述,为亚硝酸盐在腌肉制品领域更安全使用提供参考。

  2. Interspecific variation and plasticity in hemoglobin nitrite reductase activity and its correlation with oxygen affinity in vertebrates

    DEFF Research Database (Denmark)

    Jensen, Frank B; Kolind, Rasmus A H; Jensen, Natashia S

    2017-01-01

    determines oxygen affinity. In the present study we investigated nitrite reductase activity and O2 affinity in Hbs from ten different vertebrate species under identical conditions to disclose interspecific variations and allow an extended test for a correlation between the rate constant for nitrite reduction......-dependent manner. The initial second order rate constant of the deoxyHb-mediated nitrite reduction showed a strong curvilinear correlation with oxygen affinity among all ectothermic vertebrates, and the relationship also applied to plastic variations of Hb properties via organic phosphates. The relationship...

  3. The Acceptor Side of Photosystem II Is the Initial Target of Nitrite Stress in Synechocystis sp. Strain PCC 6803.

    Science.gov (United States)

    Zhang, Xin; Ma, Fei; Zhu, Xi; Zhu, Junying; Rong, Junfeng; Zhan, Jiao; Chen, Hui; He, Chenliu; Wang, Qiang

    2017-02-01

    Nitrite, a common form of inorganic nitrogen (N), can be used as a nitrogen source through N assimilation. However, high levels of nitrite depress photosynthesis in various organisms. In this study, we investigated which components of the photosynthetic electron transfer chain are targeted by nitrite stress in Synechocystis sp. strain PCC 6803 cells. Measurements of whole-chain and photosystem II (PSII)-mediated electron transport activities revealed that high levels of nitrite primarily impair electron flow in PSII. Changes in PSII activity in response to nitrite stress occurred in two distinct phases. During the first phase, which occurred in the first 3 h of nitrite treatment, electron transfer from the primary quinone acceptor (QA) to the secondary quinone acceptor (QB) was retarded, as indicated by chlorophyll (Chl) a fluorescence induction, S-state distribution, and QA(-) reoxidation tests. In the second phase, which occurred after 6 h of nitrite exposure, the reaction center was inactivated and the donor side of photosystem II was inhibited, as revealed by changes in Chl fluorescence parameters and thermoluminescence and by immunoblot analysis. Our data suggest that nitrite stress is highly damaging to PSII and disrupts PSII activity by a stepwise mechanism in which the acceptor side is the initial target. IMPORTANCE In our previous studies, an alga-based technology was proposed to fix the large amounts of nitrite that are released from NOX-rich flue gases and proved to be a promising industrial strategy for flue gas NOX bioremediation (W. Chen et al., Environ Sci Technol 50:1620-1627, 2016, https://doi.org/10.1021/acs.est.5b04696; X. Zhang et al., Environ Sci Technol 48:10497-10504, 2014, https://doi.org/10.1021/es5013824). However, the toxic effects of high concentrations of nitrite on algal cells remain obscure. The analysis of growth rates, photochemistry, and protein profiles in our study provides important evidence that the inhibition by nitrite occurs

  4. Effect of betaine supplementation on plasma nitrate/nitrite in exercise-trained men

    Directory of Open Access Journals (Sweden)

    McCarthy Cameron G

    2011-03-01

    Full Text Available Abstract Background Betaine, beetroot juice, and supplemental nitrate have recently been reported to improve certain aspects of exercise performance, which may be mechanistically linked to increased nitric oxide. The purpose of the present study was to investigate the effect of betaine supplementation on plasma nitrate/nitrite, a surrogate marker or nitric oxide, in exercise-trained men. Methods We used three different study designs (acute intake of betaine at 1.25 and 5.00 grams, chronic intake of betaine at 2.5 grams per day for 14 days, and chronic [6 grams of betaine per day for 7 days] followed by acute intake [6 grams], all involving exercise-trained men, to investigate the effects of orally ingested betaine on plasma nitrate/nitrite. Blood samples were collected before and at 30, 60, 90, and 120 min after ingestion of 1.25 and 5.00 grams of betaine (Study 1; before and after 14 days of betaine supplementation at a dosage of 2.5 grams (Study 2; and before and after 7 days of betaine supplementation at a dosage of 6 grams, followed by acute ingestion of 6 grams and blood measures at 30 and 60 min post ingestion (Study 3. Results In Study 1, nitrate/nitrite was relatively unaffected and no statistically significant interaction (p = 0.99, dosage (p = 0.69, or time (p = 0.91 effects were noted. Similar findings were noted in Study 2, with no statistically significant interaction (p = 0.57, condition (p = 0.98, or pre/post intervention (p = 0.17 effects noted for nitrate/nitrite. In Study 3, no statistically significant changes were noted in nitrate/nitrite between collection times (p = 0.97. Conclusion Our data indicate that acute or chronic ingestion of betaine by healthy, exercise-trained men does not impact plasma nitrate/nitrite. These findings suggest that other mechanisms aside from increasing circulating nitric oxide are likely responsible for any performance enhancing effect of betaine supplementation.

  5. Preparing electrochemical active hierarchically porous carbons for detecting nitrite in drinkable water

    KAUST Repository

    Ding, Baojun

    2016-01-13

    A class of hierarchically porous carbons were prepared by a facile dual-templating approach. The obtained samples were characterized by scanning electron microscopy, X-ray diffraction, Raman spectroscopy, Brunaner-Emmett-Teller measurement and electrochemical work station, respectively. The porous carbons could possess large specific surface area, interconnected pore structures, high conductivity and graphitizing degree. The resulting materials were used to prepare integrated modified electrodes. Based on the experimental results, the as-prepared hierarchically porous graphite (HPG) modified electrode showed the best electroactive performances toward the detection of nitrite with a detection limit of 8.1 × 10-3 mM. This HPG electrode was also repeatable and stable for 6 weeks. Moreover, this electrode was used for the determination of nitrite in drinkable water, and had acceptable recoveries. © The Royal Society of Chemistry 2016.

  6. Aggregate size and architecture determine biomass activity for one-stage partial nitritation and anammox

    DEFF Research Database (Denmark)

    Vlaeminck, S.; Terada, Akihiko; Smets, Barth F.

    2010-01-01

    In partial nitritation/anammox systems, aerobic and anoxic ammonium-oxidizing bacteria (AerAOB and AnAOB) remove ammonium from wastewater. In this process, large granular microbial aggregates enhance the performance, but little is known about this type of granulation so far. In this study......, aggregates of three reactors (A, B, C) with different inoculation and operation were studied. The test objectives were to quantify the AerAOB and AnAOB abundance and the activity balance for the different aggregate sizes, and to relate aggregate morphology, size distribution, and architecture putatively...... to the inoculation and operation of the reactors. Fluorescent in-situ hybridization (FISH) was applied on aggregate sections to quantify AerAOB and AnAOB, as well as to visualize the aggregate architecture. The activity balance of the aggregates was calculated as the nitrite accumulation rate ratio (NARR), i...

  7. Supporting palladium metal on gold nanoparticles improves its catalysis for nitrite reduction

    Science.gov (United States)

    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

  8. Estimation of nitrite, nitrate, and N-nitrosamines in drinking water and soft drinks

    Energy Technology Data Exchange (ETDEWEB)

    Alwan, S.M.; Jawad, I.M.; Abdul-Rahman, S.K.; Al-Kafaji, S.H.

    1987-09-01

    A survey for the determination of the carcinogenic N-nitrosamines in drinking water and selected soft drinks was achieved, using a GLC method. This shows that these substances occur predominantly in the drinks. The average contents of dimethylnitrosamine and diethylnitrosamine in drinking water were 4.1 ..mu..g/L and 0.2 ..mu..g/L respectively, while they were approximately 3.9 ..mu..g/L and 0.43 ..mu..g/L in soft drinks. Nitrite and nitrate contents in drinking water samples were also estimated, as potential factors for the formation of N-nitrosamines. The mean contents of nitrite and nitrate in drinking water were 65 g/L and 10.8 g/L respectively.

  9. Nitric oxide formation from the reaction of nitrite with carp and rabbit hemoglobin at intermediate oxygen saturations

    DEFF Research Database (Denmark)

    Jensen, Frank Bo

    2008-01-01

    The nitrite reductase activity of deoxyhemoglobin has received much recent interest because the nitric oxide produced in this reaction may participate in blood flow regulation during hypoxia. The present study used spectral deconvolution to characterize the reaction of nitrite with carp and rabbit...... hemoglobin at different constant oxygen tensions that generate the full range of physiological relevant oxygen saturations. Carp is a hypoxia-tolerant species with very high hemoglobin oxygen affinity, and the high R-state character and low redox potential of the hemoglobin is hypothesized to promote...... NO generation from nitrite. The reaction of nitrite with deoxyhemoglobin leads to a 1 : 1 formation of nitrosylhemoglobin and methemoglobin in both species. At intermediate oxygen saturations, the reaction with deoxyhemoglobin is clearly favored over that with oxyhemoglobin, and the oxyhemoglobin reaction...

  10. Nitric oxide availability in deeply hypoxic crucian carp: acute and chronic changes and utilization of ambient nitrite reservoirs.

    Science.gov (United States)

    Hansen, Marie N; Gerber, Lucie; Jensen, Frank B

    2016-03-15

    Recent research suggest that anoxia-tolerant fish transfer extracellular nitrite into the tissues, where it is used for nitric oxide (NO) generation, iron-nitrosylation, and S-nitrosation of proteins, as part of the cytoprotective response toward prolonged hypoxia and subsequent reoxygenation. We hypothesized that crucian carp take up ambient nitrite and use it as a source of cellular NO availability during hypoxia. Fish were exposed for 1 day to normoxia (Po2 > 140 mmHg) and deep hypoxia (1 nitric oxide synthase-2 gene variant. The data support that ambient nitrite is taken up across the gills to be distributed via the blood to the tissues, particularly the heart, where it assists in cytoprotection and other functions. Cardiac nitrite was not elevated in acutely exposed fish, revealing that the response requires time. NO metabolite levels were higher during acute than chronic exposures, possibly caused by increased swimming activity and stress in acutely exposed fish.

  11. Control of hydrogen sulfide production in oil fields by managing microbial communities through nitrate or nitrite addition

    Science.gov (United States)

    Hubert, Casey R. J.

    Nitrate or nitrite injection into oil reservoirs during water flooding has the potential to control biological souring, the production of hydrogen sulfide (H2S) by sulfate-reducing bacteria (SRB). Souring control is essential because sulfide is toxic, sulfide precipitates can plug reservoir formations, souring lowers crude oil value, and SRB induce corrosion. Nitrate and nitrite can stimulate heterotrophic nitrate- or nitrite-reducing bacteria (hNRB) and nitrate- or nitrite-reducing, sulfide oxidizing bacteria (NRSOB). Nitrite also inhibits SRB activity by blocking the sulfate reduction pathway. Continuous up-flow packed-bed bioreactors were inoculated with produced water from the Coleville oil field to establish sulfide-producing biofilms similar to those found in sour reservoirs. Nitrate or nitrite addition to bioreactors indicated that the dose required for hNRB or NR-SOB to control souring depended on the concentration of oil organics. Either mechanism mediates the net removal of oil organics (lactate) with nitrate or nitrite, with lower doses of nitrate required due to its greater oxidative power. Microbial community analysis by reverse sample genome probing (RSGP) revealed that NR-SOB mediated sulfide removal at low nitrate or nitrite concentrations when lactate was still available to SRB and the redox potential was low. At high nitrate doses hNRB oxidized lactate directly, produced nitrite and maintained a high redox potential, thus excluding SRB activity. Facultatively chemolithotrophic Campylobacter sp. strains were isolated from the bioreactors and incorporated into RSGP analyses, revealing their dominance in both NR-SOB- and hNRB-containing communities. The metabolic flexibility of these strains may confer a competitive advantage over obligate chemolithotrophs like Thiomicrospira sp. strain CVO or hNRB that do not have NR-SOB activity like newly isolated Thauera sp. and Rhodobacter sp. strains. A single high dose of nitrite resulted in immediate

  12. Ultraviolet irradiation effects incorporation of nitrate and nitrite nitrogen into aquatic natural organic matter

    Science.gov (United States)

    Thorn, Kevin A.; Cox, Larry G.

    2012-01-01

    One of the concerns regarding the safety and efficacy of ultraviolet radiation for treatment of drinking water and wastewater is the fate of nitrate, particularly its photolysis to nitrite. In this study, 15N NMR was used to establish for the first time that UV irradiation effects the incorporation of nitrate and nitrite nitrogen into aquatic natural organic matter (NOM). Irradiation of 15N-labeled nitrate in aqueous solution with an unfiltered medium pressure mercury lamp resulted in the incorporation of nitrogen into Suwannee River NOM (SRNOM) via nitrosation and other reactions over a range of pH from approximately 3.2 to 8.0, both in the presence and absence of bicarbonate, confirming photonitrosation of the NOM. The major forms of the incorporated label include nitrosophenol, oxime/nitro, pyridine, nitrile, and amide nitrogens. Natural organic matter also catalyzed the reduction of nitrate to ammonia on irradiation. The nitrosophenol and oxime/nitro nitrogens were found to be susceptible to photodegradation on further irradiation when nitrate was removed from the system. At pH 7.5, unfiltered irradiation resulted in the incorporation of 15N-labeled nitrite into SRNOM in the form of amide, nitrile, and pyridine nitrogen. In the presence of bicarbonate at pH 7.4, Pyrex filtered (cutoff below 290–300 nm) irradiation also effected incorporation of nitrite into SRNOM as amide nitrogen. We speculate that nitrosation of NOM from the UV irradiation of nitrate also leads to production of nitrogen gas and nitrous oxide, a process that may be termed photo-chemodenitrification. Irradiation of SRNOM alone resulted in transformation or loss of naturally abundant heterocyclic nitrogens.

  13. The Genome of Nitrospina gracilis Illuminates the Metabolism and Evolution of the Major Marine Nitrite Oxidizer

    OpenAIRE

    2013-01-01

    In marine systems, nitrate is the major reservoir of inorganic fixed nitrogen. The only known biological nitrate-forming reaction is nitrite oxidation, but despite its importance, our knowledge of the organisms catalyzing this key process in the marine N-cycle is very limited. The most frequently encountered marine NOB are related to Nitrospina gracilis, an aerobic chemolithoautotrophic bacterium isolated from ocean surface waters. To date, limited physiological and genomic data for this orga...

  14. The genome of Nitrospina gracilis illuminates the metabolism and evolution of the major marine nitrite oxidizer

    OpenAIRE

    2013-01-01

    In marine systems, nitrate is the major reservoir of inorganic fixed nitrogen. The only known biological nitrate-forming reaction is nitrite oxidation, but despite its importance, our knowledge of the organisms catalyzing this key process in the marine N-cycle is very limited. The most frequently encountered marine NOB are related to Nitrospina gracilis, an aerobic chemolithoautotrophic bacterium isolated from ocean surface waters. To date, limited physiological and genomic data for this orga...

  15. Denitrification of nitrate and nitrite by 'Candidatus Accumulibacter phosphatis' clade IC.

    Science.gov (United States)

    Saad, Sondos A; Welles, Laurens; Abbas, Ben; Lopez-Vazquez, Carlos M; van Loosdrecht, Mark C M; Brdjanovic, Damir

    2016-11-15

    Phosphate accumulating organisms (PAO) are assumed to use nitrate as external electron acceptor, allowing an efficient integration of simultaneous nitrogen and phosphate removal with minimal organic carbon (COD) requirements. However, contradicting findings appear in literature regarding the denitrification capacities of PAO due to the lack of clade specific highly enriched PAO cultures. Whereas some studies suggest that only PAO clade I may be capable of using nitrate as external electron acceptor for anoxic P-uptake, other studies indicate that PAO clade II may be responsible for anoxic P-removal. In the present study, a highly enriched PAO clade IC culture (>99% according to FISH) was cultivated in an SBR operated under Anaerobic/Oxic conditions and subsequently exposed to Anaerobic/Anoxic/Oxic conditions using nitrate as electron acceptor. Before and after acclimatization to the presence of nitrate, the aerobic and anoxic (nitrate and nitrite) activities of the PAO I culture were assessed through the execution of batch tests using either acetate or propionate as electron donor. In the presence of nitrate, significant P-uptake by PAO I was not observed before or after acclimatization. Using nitrite as electron acceptor, limited nitrite removal rates were observed before acclimatization with lower rates in the acetate fed reactor without P-uptake and slightly higher in the propionate fed reactor with a marginal anoxic P-uptake. Only after acclimatization to nitrate, simultaneous P and nitrite removal was observed. This study suggests that PAO clade IC is not capable of using nitrate as external electron acceptor for anoxic P-removal. The elucidation of the metabolic capacities for individual PAO clades helps in better understanding and optimization of the relation between microbial ecology and process performance in enhanced biological phosphate removal processes.

  16. Analysis of digital gene expression profiling in hemocytes of white shrimp Litopenaeus vannamei under nitrite stress.

    Science.gov (United States)

    Guo, Hui; Xian, Jian-An; Wang, An-Li

    2016-09-01

    Accumulation of nitrite in water is highly toxic to aquatic animals. To understand immune responses in shrimp under such environmental stress, a digital gene expression (DGE) technology was applied to detect the gene expression profile of the Litopenaeus vannamei hemocytes in response to nitrite for 48 h. A total of 1922 differently expressed unigenes were generated. Of these transcripts, 1269 and 653 genes were up- or down-regulated respectively. Functional categorization and pathways of the differentially expressed genes revealed that immune defense, xenobiotics biodegradation and metabolism, amino acid and nucleobase metabolic process, apoptosis were the differentially regulated processes occurring during nitrite stress. We selected 19 differential expression transcripts (DETs) to validate the sequencing results by real time quantitative PCR (qPCR). The Pearson's correlation coefficient (R) of the 19 DETs was 0.843, which confirmed the consistency and accuracy between these two approaches. Subsequently, we screened 10 genes to examine the changes in the time course of gene expression in more detail. The results indicated that expressions of ATP-binding cassette transporter (ABC transporter), caspase10, QM protein, C type lectin 4 (CTL4), protein disulfide isomerase (PDI), serine protease inhibitor 8 (SPI8), transglutaminase (TGase), chitinase1, inhibitors of apoptosis proteins (IAP) and cytochrome P450 enzyme (CYP450) were induced to participate in the anti-stress defense against nitrite. These results will provide a reference for follow-up study of molecular toxicology and valuable gene information for better understanding of immune response in L. vannamei under environmental stress.

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

    Science.gov (United States)

    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.

  18. Short-and long-term effects of ammonia and nitrite on the anammox process

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, I.; Campos, J. L.; Mosquera-Corral, A.; Mendez, R.

    2009-07-01

    Auto trophic anaerobic ammonium oxidation (Anammox) process is a feasible alternative to treat industrial wastewater with high ammonia concentration but low content of organic matter. In this process ammonium and nitrite are used by Planctomycete-type bacteria under anoxic conditions to generate nitrogen gas. Both substrates can exert inhibitory effects on the process, causing the decrease of the specific activity of the biomass and the loss of the performance and stability of reactors. (Author)

  19. Electroencephalographic Response to Sodium Nitrite May Predict Delayed Cerebral Ischemia After Severe Subarachnoid Hemorrhage

    Science.gov (United States)

    Rowland, Matthew J.; Ezra, Martyn; Herigstad, Mari; Hayen, Anja; Sleigh, Jamie W.; Westbrook, Jon; Warnaby, Catherine E.; Pattinson, Kyle T. S.

    2016-01-01

    Objectives: Aneurysmal subarachnoid hemorrhage often leads to death and poor clinical outcome. Injury occurring during the first 72 hours is termed “early brain injury,” with disruption of the nitric oxide pathway playing an important pathophysiologic role in its development. Quantitative electroencephalographic variables, such as α/δ frequency ratio, are surrogate markers of cerebral ischemia. This study assessed the quantitative electroencephalographic response to a cerebral nitric oxide donor (intravenous sodium nitrite) to explore whether this correlates with the eventual development of delayed cerebral ischemia. Design: Unblinded pilot study testing response to drug intervention. Setting: Neuroscience ICU, John Radcliffe Hospital, Oxford, United Kingdom. Patients: Fourteen World Federation of Neurosurgeons grades 3, 4, and 5 patients (mean age, 52.8 yr [range, 41–69 yr]; 11 women). Interventions: IV sodium nitrite (10 μg/kg/min) for 1 hour. Measurements and Main Results: Continuous electroencephalographic recording for 2 hours. The alpha/delta frequency ratio was measured before and during IV sodium nitrite infusion. Seven of 14 patients developed delayed cerebral ischemia. There was a +30% to +118% (range) increase in the alpha/delta frequency ratio in patients who did not develop delayed cerebral ischemia (p < 0.0001) but an overall decrease in the alpha/delta frequency ratio in those patients who did develop delayed cerebral ischemia (range, +11% to –31%) (p = 0.006, multivariate analysis accounting for major confounds). Conclusions: Administration of sodium nitrite after severe subarachnoid hemorrhage differentially influences quantitative electroencephalographic variables depending on the patient’s susceptibility to development of delayed cerebral ischemia. With further validation in a larger sample size, this response may be developed as a tool for risk stratification after aneurysmal subarachnoid hemorrhage. PMID:27441898

  20. Formation of genotoxic nitroPAH compounds in fish exposed to ambient nitrite and PAH

    Digital Repository Service at National Institute of Oceanography (India)

    Shailaja, M.S.; Rajamanickam, R.; Wahidullah, S.

    -relevant, sub-lethal concentrations of the two stressors, and characterising the biliary metabolites. Materials and Methods a) Exposure protocol: Juvenile O. mossambicus (9.3 to 11 g, n=24) obtained from a local estuarine fish farm were acclimatized... medium were 1 mg l-1 and 1 ? M, respectively. Control fish (n=6) were exposed to equivalent concentrations of nitrite or phenanthrene only. In another set of experiments, O. mossambicus (n=6) were administered a single intra...

  1. Mechanism of Pitting Corrosion Prevention by Nitrite in Carbon Steel Exposed to Dilute Salt Solutions

    Energy Technology Data Exchange (ETDEWEB)

    Philip E. Zapp; John W. Van Zee

    2002-02-01

    The research has developed a broad fundamental understanding of the inhibition action of nitrite ions in preventing nitrate pitting corrosion of carbon steel tanks containing high-level radioactive waste. This fundamental understanding can be applied to specific situations during waste removal for permanent disposition and waste tank closure to ensure that the tanks are maintained safely. The results of the research provide the insight necessary to develop solutions that prevent further degradation.

  2. Microbiology, ecology, and application of the nitrite-dependent anaerobic methane oxidation process

    OpenAIRE

    Li-Dong eShen; Bao-lan eHu

    2012-01-01

    Nitrite-dependent anaerobic methane oxidation (n-damo), which couples the anaerobic oxidation of methane to denitrification, is a recently discovered process observed in Candidatus Methylomirabilis oxyfera. M. oxyfera is affiliated with the NC10 phylum, a phylum having no members in pure culture. Based on the isotopic labeling experiments, it is hypothesized that M. oxyfera has an unusual intra-aerobic pathway for the production of oxygen via the dismutation of nitric oxide into dinitrogen ga...

  3. Susceptibility of Clostridium difficile to the food preservatives sodium nitrite, sodium nitrate and sodium metabisulphite.

    Science.gov (United States)

    Lim, Su-Chen; Foster, Niki F; Riley, Thomas V

    2016-02-01

    Clostridium difficile is an important enteric pathogen of humans and food animals. Recently it has been isolated from retail foods with prevalences up to 42%, prompting concern that contaminated foods may be one of the reasons for increased community-acquired C. difficile infection (CA-CDI). A number of studies have examined the prevalence of C. difficile in raw meats and fresh vegetables; however, fewer studies have examined the prevalence of C. difficile in ready-to-eat meat. The aim of this study was to investigate the in vitro susceptibility of 11 C. difficile isolates of food animal and retail food origins to food preservatives commonly used in ready-to-eat meats. The broth microdilution method was used to determine the minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) for sodium nitrite, sodium nitrate and sodium metabisulphite against C. difficile. Checkerboard assays were used to investigate the combined effect of sodium nitrite and sodium nitrate, commonly used in combination in meats. Modal MIC values for sodium nitrite, sodium nitrate and sodium metabisulphite were 250 μg/ml, >4000 μg/ml and 1000 μg/ml, respectively. No bactericidal activity was observed for all three food preservatives. The checkerboard assays showed indifferent interaction between sodium nitrite and sodium nitrate. This study demonstrated that C. difficile can survive in the presence of food preservatives at concentrations higher than the current maximum permitted levels allowed in ready-to-eat meats. The possibility of retail ready-to-eat meats contaminated with C. difficile acting as a source of CDI needs to be investigated.

  4. Nitrate-nitrite-nitrosamines exposure and the risk of type 1 diabetes: A review of current data

    Science.gov (United States)

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

    2016-01-01

    The potential toxic effects of nitrate-nitrite-nitrosamine on pancreatic β cell have remained a controversial issue over the past two decades. In this study, we reviewed epidemiological studies investigated the associations between nitrate-nitrite-nitrosamines exposure, from both diet and drinking water to ascertain whether these compounds may contribute to development of type 1 diabetes. To identify relevant studies, a systematic search strategy of PubMed, Scopus, and Science Direct was conducted using queries including the key words “nitrate”, “nitrite”, “nitrosamine” with “type 1 diabetes” or “insulin dependent diabetes mellitus”. All searches were limited to studies published in English. Ecologic surveys, case-control and cohort studies have indicated conflicting results in relation to nitrate-nitrite exposure from drinking water and the risk of type 1 diabetes. A null, sometimes even negative association has been mainly reported in regions with a mean nitrate levels 40-80 mg/L. Limited data are available regarding the potential diabetogenic effect of nitrite from drinking water, although there is evidence indicating dietary nitrite could be a risk factor for development of type 1 diabetes, an effect however that seems to be significant in a higher range of acceptable limit for nitrate/nitrite. Current data regarding dietary exposure of nitrosamine and development of type 1 diabetes is also inconsistent. Considering to an increasing trend of type 1 diabetes mellitus (T1DM) along with an elevated nitrate-nitrite exposure, additional research is critical to clarify potential harmful effects of nitrate-nitrite-nitrosamine exposure on β-cell autoimmunity and the risk of T1DM. PMID:27795817

  5. Fine structure characterization of zero-valent iron nanoparticles for decontamination of nitrites and nitrates in wastewater and groundwater

    Directory of Open Access Journals (Sweden)

    Kuen-Song Lin et al

    2008-01-01

    Full Text Available The main objectives of the present study were to investigate the chemical reduction of nitrate or nitrite species by zero-valent iron nanoparticle (ZVIN in aqueous solution and related reaction kinetics or mechanisms using fine structure characterization. This work also exemplifies the utilization of field emission-scanning electron microscope (FE–SEM, transmission electron microscopy (TEM, and x-ray diffraction (XRD to reveal the speciation and possible reaction pathway in a very complex adsorption and redox reaction process. Experimentally, ZVIN of this study was prepared by sodium borohydride reduction method at room temperature and ambient pressure. The morphology of as-synthesized ZVIN shows that the nearly ball and ultrafine particles ranged of 20–50 nm were observed with FE–SEM or TEM analysis. The kinetic model of nitrites or nitrates reductive reaction by ZVIN is proposed as a pseudo first-order kinetic equation. The nitrite and nitrate removal efficiencies using ZVIN were found 65–83% and 51–68%, respectively, based on three different initial concentrations. Based on the XRD pattern analyses, it is found that the quantitative relationship between nitrite and Fe(III or Fe(II is similar to the one between nitrate and Fe(III in the ZVIN study. The possible reason is due to the faster nitrite reduction by ZVIN. In fact, the occurrence of the relative faster nitrite reductive reaction suggested that the passivation of the ZVIN have a significant contribution to iron corrosion. The extended x-ray absorption fine structure (EXAFS or x-ray absorption near edge structure (XANES spectra show that the nitrites or nitrates reduce to N2 or NH3 while oxidizing the ZVIN to Fe2O3 or Fe3O4 electrochemically. It is also very clear that decontamination of nitrate or nitrite species in groundwater via the in-situ remediation with a ZVIN permeable reactive barrier would be environmentally attractive.

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

    Science.gov (United States)

    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) 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.

  7. Effect of freeze-dried leek powder (FDLP) and nitrite level on processing and quality characteristics of fermented sausages.

    Science.gov (United States)

    Tsoukalas, D S; Katsanidis, E; Marantidou, S; Bloukas, J G

    2011-02-01

    Fermented sausages were produced with 0.84% and 1.68% freeze-dried leek powder (FDLP), providing 75 and 150 mg/kg NaNO(3), respectively, and three levels of added nitrite (0, 75, and 150 mg/kg NaNO(2). A control treatment was also produced with 150 mg/kg NaNO(2). Sausages with FDLP were darker and yellower (psausages (pfermented sausages, as it results in a 50% reduction in added nitrite.

  8. Behavior of Staphylococcus aureus and autochthone microbiota in fresh sausages added of sodium nitrite and stored under refrigeration

    OpenAIRE

    Lucyanne Maria Moraes Correia; Juliano Gonçalves Pereira; José Paes de Almeida Nogueira Pinto; Vinicius Cunha Barcellos; Luciano dos Santos Bersot

    2014-01-01

    Fresh sausages are cured meat products that may be contaminated with Staphylococcus aureus during the manufacturing procedure, which is frequently related with inadequate handling practices. The use of nitrite in meat products has proven efficacy against Clostridium botulinum, and studies indicate that bactericidal action against S. aureus depends on factors that are intrinsic and extrinsic to the product. The objective of the present study was to evaluate the effect of nitrite concentration,...

  9. Yield of Ozone, Nitrite Nitrogen and Hydrogen Peroxide Versus Discharge Parameter Using APPJ Under Water

    Science.gov (United States)

    Chen, Bingyan; Zhu, Changping; Fei, Juntao; He, Xiang; Yin, Cheng; Wang, Yuan; Gao, Ying; Jiang, Yongfeng; Wen, Wen; Chen, Longwei

    2016-03-01

    Discharge plasma in and in contact with water can be accompanied with ultraviolet radiation and electron impact, thus can generate hydroxyl radicals, ozone, nitrite nitrogen and hydrogen peroxide. In this paper, a non-equilibrium plasma processing system was established by means of an atmospheric pressure plasma jet immersed in water. The hydroxyl intensities and discharge energy waveforms were tested. The results show that the positive and negative discharge energy peaks were asymmetric, where the positive discharge energy peak was greater than the negative one. Meanwhile, the yield of ozone and nitrite nitrogen was enhanced with the increase of both the treatment time and the discharge energy. Moreover, the pH value of treated water was reduced rapidly and maintained at a lower level. The residual concentration of hydrogen peroxide in APPJ treated water was kept at a low level. Additionally, both the efficiency energy ratio of the yield of ozone and nitrite nitrogen and that of the removal of p-nitrophenol increased as a function of discharge energy and discharge voltage. The experimental results were fully analyzed and the chemical reaction equations and the physical processes of discharges in water were given. supported by National Natural Science Foundation of China (Nos. 11274092, 11404092, 61401146), the Nantong Science and Technology Project, Nantong, China (No. BK2014024), the Open Project of Jiangsu Province Key Laboratory of Environmental Engineering, Nanjing, China (No. KF2014001), and the Fundamental Research Funds for the Central Universities of China (No. 2014B11414)

  10. Salivary surrogates of plasma nitrite and catecholamines during a 21-week training season in swimmers.

    Directory of Open Access Journals (Sweden)

    Miguel Mauricio Díaz Gómez

    Full Text Available The collection of samples of saliva is noninvasive and straightforward, which turns saliva into an ideal fluid for monitoring the adaptive response to training. Here, we investigated the response of the salivary proteins alpha-amylase (sAA, chromogranin A (sCgA, and the concentration of total protein (sTP as well as salivary nitrite (sNO2 in relation to plasma catecholamines and plasma nitrite (pNO2, respectively. The variation in these markers was compared to the intensity and load of training during a 21-week training season in 12 elite swimmers. Overall, the salivary proteins tracked the concentration of plasma adrenaline and were inversely correlated with the training outcomes. No correlations were observed between sNO2 and pNO2. However, sNO2 correlated positively with the intensity and load of training. We argue that the decrease in sympathetic activity is responsible for the decrease in the concentration of proteins throughout the training season. Furthermore, the increase in nitrite is likely to reflect changes in hemodynamics and regulation of vascular tone. The association of the salivary markers with the training outcomes underlines their potential as noninvasive markers of training status in professional athletes.

  11. Impact of temperature on ammonium and nitrite removal rates in RAS moving bed biofilters

    DEFF Research Database (Denmark)

    Kinyage, John Peter Hewa; Pedersen, Lars-Flemming

    2016-01-01

    at each of the six temperatures (6, 12, 18, 24, 30 and 36 °C) and then spiked with ammonium chloride or sodium nitrite under identical conditions. The average surface specific TAN removal (STR) increased a six-fold from 6 to 30 °C (0.04–0.25 g TAN m−2 day−1) and dropped significantly at 36 °C–0.14 g TAN m......The impact of temperature on bacterial processes is well known; however temperature related data on nitrification rates in aquaculture systems are fragmented and compiled from different studies. We sought to determine ammonium and nitrite removal kinetics over a temperature range from 6 to 36 °C...... by using moving bed bio-elements from a freshwater RAS in steady state operated at 18 °C. The impact of temperature on ammonium and nitrite oxidation rates was evaluated by transferring the colonized bio elements to six liter batch reactors (triplicated setup). Each reactor was acclimatized for 24 h...

  12. Effect of Metal Ions on the Formation of Trichloronitromethane during Chlorination of Catechol and Nitrite.

    Science.gov (United States)

    Gan, Guojuan; Mei, Rongwu; Qiu, Lin; Hong, Huachang; Wang, Qingjun; Mazumder, Asit; Wu, Shikai; Pan, Xiangliang; Liang, Yan

    2016-11-01

    Catechol, nitrite, and dissolved metals are ubiquitous in source drinking water. Catechol and nitrite have been identified as precursors for halonitromethanes (HNMs), but the effect of metal ions on HNM formation during chlorination remains unclear. The main objective of this study was to investigate the effect of metal ions (Fe, Ti, Al) on the formation of trichloronitromethane (TCNM) (the most representative HNM species in disinfected water) on chlorinating catechol and nitrite. Trichloronitromethane was extracted by methyl tert-butyl ether and detected by gas chromatography. The results show that metal ions promoted the formation of TCNM and that the enhancement efficiency followed the order of Fe > Ti > Al. Trichloronitromethane formation increased greatly within 2 h, and a basic condition (pH 8-9) favored TCNM formation more than acidic or neutral conditions. The conjoint effect of the metal-ion mixtures was shown to be similar to that of the single metal ion having the highest promoting effect on TCNM formation. Our results strongly suggest that metal ions play a significant role in enhancing TCNM formation.

  13. Influence of temperature on the partial nitritation of reject water in a granular sequencing batch reactor.

    Science.gov (United States)

    López-Palau, Sílvia; Sancho, Irene; Pinto, Antonio; Dosta, Joan; Mata-Alvarez, Joan

    2013-01-01

    Two Granular Sequencing Batch Reactors were operated to perform partial nitrification of sludge reject water at different temperatures, from 25-41 degrees C. Every temperature was fixed for about a month in order to evaluate the nitritation rate, morphological features of aggregates and bacterial populations. The optimum temperature was found between 33 and 37 degrees C in terms of nitritation rate. Morphological features of granules did not show significant changes with temperature in the range between 28 and 37 degrees C; Feret diameter remained at 5.8 +/- 0.7mm and roundness was 0.76 +/- 0.02. Lower temperatures promoted the appearance of filamentous bacteria, leading to an increase of the sludge volume index (SVI) and a consequent reduction of biomass concentration. When the temperature was increased to 39 degrees C, more than the 80% of aggregates showed a diameter higher than 6mm but density decreased from 28 to 19 g VSS L(-1), resulting in an increase of the SVI from 33 to 80 mL g(-1). The establishment of 41 degrees C caused a rapid destabilization of the system and nitritation activity disappeared. Bacterial populations did not experience significant changes during the experimental period and Nitrosomonas was the dominant species at all the temperatures assayed.

  14. Achieving nitritation and anammox enrichment in a single moving-bed biofilm reactor treating reject water.

    Science.gov (United States)

    Zekker, I; Rikmann, E; Tenno, T; Saluste, A; Tomingas, M; Menert, A; Loorits, L; Lemmiksoo, Vallo; Tenno, T

    2012-01-01

    A biofilm with high nitrifying efficiency was converted into a nitritating and thereafter a nitritating-anammox biofilm in a moving-bed biofilm reactor at 26.5 (+/- 0.5) degrees C by means of a combination of intermittent aeration, low dissolved oxygen concentration, low hydraulic retention time, free ammonia and furthermore, also by elevated HCO3- concentration. Nitrite-oxidizing bacteria (NOB) were more effectively suppressed by an enhanced HCO3- concentration range of 1200-2350 mg/L as opposed to free-ammonia-based process control where NOBs recovered from inhibition; the respective total-nitrogen removal rates were 0.3 kg N/(m3 x d) and 0.2 kg N/(m3 x d). The biofilm modification strategies resulted in a shift in bacterial community as the NOB Nitrobacter spp. were replaced with NOB belonging to the genus Nitrospira spp. and were closely related to Candidatus Nitrospira defluvii. A community of anaerobic ammonium-oxidizing microorganisms -uncultured Planctomycetales bacterium clone P4 (closely related to Candidatus Brocadia fulgida)--was developed.

  15. Effects of hemin and nitrite on intestinal tumorigenesis in the A/J Min/+ mouse model.

    Directory of Open Access Journals (Sweden)

    Marianne Sødring

    Full Text Available Red and processed meats are considered risk factors for colorectal cancer (CRC; however, the underlying mechanisms are still unclear. One cause for the potential link between CRC and meat is the heme iron in red meat. Two pathways by which heme and CRC promotion may be linked have been suggested: fat peroxidation and N-nitrosation. In the present work we have used the novel A/J Min/+ mouse model to test the effects of dietary hemin (a model of red meat, and hemin in combination with nitrite (a model of processed meat on intestinal tumorigenesis. Mice were fed a low Ca2+ and vitamin D semi-synthetic diet with added hemin and/or nitrite for 8 weeks post weaning, before termination followed by excision and examination of the intestinal tract. Our results indicate that dietary hemin decreased the number of colonic lesions in the A/J Min/+ mouse. However, our results also showed that the opposite occurred in the small intestine, where dietary hemin appeared to stimulate tumor growth. Furthermore, we find that nitrite, which did not have an effect in the colon, appeared to have a suppressive effect on tumor growth in the small intestine.

  16. Nitrite Oxidation with Copper-Cobalt Nanoparticles on Carbon Nanotubes Doped Conducting Polymer PEDOT Composite.

    Science.gov (United States)

    Wang, Junjie; Xu, Guiyun; Wang, Wei; Xu, Shenghao; Luo, Xiliang

    2015-09-01

    Copper-cobalt bimetal nanoparticles (Cu-Co) have been electrochemically prepared on glassy carbon electrodes (GCEs), which were electrodeposited with conducting polymer nanocomposites of poly(3,4-ethylenedioxythiophene) (PEDOT) doped with carbon nanotubes (CNTs). Owing to their good conductivity, high mechanical strength, and large surface area, the PEDOT/CNTs composites offered excellent substrates for the electrochemical deposition of Cu-Co nanoparticles. As a result of their nanostructure and the synergic effect between Cu and Co, the Cu-Co/PEDOT/CNTs composites exhibited significantly enhanced catalytic activity towards the electrochemical oxidation of nitrite. Under optimized conditions, the nanocomposite-modified electrodes had a fast response time within 2 s and a linear range from 0.5 to 430 μm for the detection of nitrite, with a detection limit of 60 nm. Moreover, the Cu-Co/PEDOT/CNTs composites were highly stable, and the prepared nitrite sensors could retain more than 96 % of their initial response after 30 days.

  17. Redox-coupled proton transfer mechanism in nitrite reductase revealed by femtosecond crystallography.

    Science.gov (United States)

    Fukuda, Yohta; Tse, Ka Man; Nakane, Takanori; Nakatsu, Toru; Suzuki, Mamoru; Sugahara, Michihiro; Inoue, Shigeyuki; Masuda, Tetsuya; Yumoto, Fumiaki; Matsugaki, Naohiro; Nango, Eriko; Tono, Kensuke; Joti, Yasumasa; Kameshima, Takashi; Song, Changyong; Hatsui, Takaki; Yabashi, Makina; Nureki, Osamu; Murphy, Michael E P; Inoue, Tsuyoshi; Iwata, So; Mizohata, Eiichi

    2016-03-15

    Proton-coupled electron transfer (PCET), a ubiquitous phenomenon in biological systems, plays an essential role in copper nitrite reductase (CuNiR), the key metalloenzyme in microbial denitrification of the global nitrogen cycle. Analyses of the nitrite reduction mechanism in CuNiR with conventional synchrotron radiation crystallography (SRX) have been faced with difficulties, because X-ray photoreduction changes the native structures of metal centers and the enzyme-substrate complex. Using serial femtosecond crystallography (SFX), we determined the intact structures of CuNiR in the resting state and the nitrite complex (NC) state at 2.03- and 1.60-Å resolution, respectively. Furthermore, the SRX NC structure representing a transient state in the catalytic cycle was determined at 1.30-Å resolution. Comparison between SRX and SFX structures revealed that photoreduction changes the coordination manner of the substrate and that catalytically important His255 can switch hydrogen bond partners between the backbone carbonyl oxygen of nearby Glu279 and the side-chain hydroxyl group of Thr280. These findings, which SRX has failed to uncover, propose a redox-coupled proton switch for PCET. This concept can explain how proton transfer to the substrate is involved in intramolecular electron transfer and why substrate binding accelerates PCET. Our study demonstrates the potential of SFX as a powerful tool to study redox processes in metalloenzymes.

  18. Simultaneous removal of ammonia nitrogen and manganese from wastewater using nitrite by electrochemical method.

    Science.gov (United States)

    Shu, Jiancheng; Liu, Renlong; Liu, Zuohua; Qiu, Jiang; Chen, Hongliang; Tao, Changyuan

    2017-02-01

    In this work, nitrite was developed to simultaneously remove manganese and ammonia nitrogen from wastewater by the electrochemical method. The characteristics of electrolytic reaction were observed via cyclic voltammograms. Moreover, the mole ratio of nitrite and ammonia nitrogen, voltage, and initial pH value, which affected the removal efficiency of ammonia nitrogen and manganese, were investigated. The results showed that the concentration of ammonia nitrogen in wastewater could be reduced from 120.2 to 6.0 mg L(-1), and manganese could be simultaneously removed from 302.4 to 1.5 mg L(-1) at initial pH of 8.0, the mole ratios of nitrite and ammonia nitrogen of 1.5:1, and voltage of 20 V direct current electrolysis for 4.0 h. XRD analysis showed that manganese dioxide was deposited on the anode, and manganese was mainly removed in the form of manganese hydroxide precipitation in the cathode chamber.

  19. Diversity and enrichment of nitrite-dependent anaerobic methane oxidizing bacteria from wastewater sludge.

    Science.gov (United States)

    Luesken, Francisca A; van Alen, Theo A; van der Biezen, Erwin; Frijters, Carla; Toonen, Ger; Kampman, Christel; Hendrickx, Tim L G; Zeeman, Grietje; Temmink, Hardy; Strous, Marc; Op den Camp, Huub J M; Jetten, Mike S M

    2011-11-01

    Recently discovered microorganisms affiliated to the bacterial phylum NC10, named "Candidatus Methylomirabilis oxyfera", perform nitrite-dependent anaerobic methane oxidation. These microorganisms could be important players in a novel way of anaerobic wastewater treatment where ammonium and residual dissolved methane might be removed at the expense of nitrate or nitrite. To find suitable inocula for reactor startup, ten selected wastewater treatment plants (WWTPs) located in The Netherlands were screened for the endogenous presence of M. oxyfera using molecular diagnostic methods. We could identify NC10 bacteria with 98% similarity to M. oxyfera in nine out of ten WWTPs tested. Sludge from one selected WWTP was used to start a new enrichment culture of NC10 bacteria. This enrichment was monitored using specific pmoA primers and M. oxyfera cells were visualized with fluorescence oligonucleotide probes. After 112 days, the enrichment consumed up to 0.4 mM NO(2)(-) per day. The results of this study show that appropriate sources of biomass, enrichment strategies, and diagnostic tools existed to start and monitor pilot scale tests for the implementation of nitrite-dependent methane oxidation in wastewater treatment at ambient temperature.

  20. Synthesis of nano-structured polypyrrole/copper electrodes for nitrate and nitrite electroreduction

    Science.gov (United States)

    Phuong Thoa Nguyen, Thi; Thinh Nguyen, Viet; Nguyen Bui, Nhat; Do, Duong Kim Bao; Pham, Anh Minh

    2010-09-01

    Nanostructured polypyrrole film was synthesized onto a copper electrode in solutions of oxalic and salicylic acids and their buffers. The electrooxidation of pyrrole to form polypyrrole film and the electroreduction of nitrate and nitrite ions at synthesized Ppy modified copper electrodes (Ppy/Cu) in potassium chloride aqueous solutions were studied using chronoamperometry. The nanoporous structure of the synthesized Ppy films was characterized by scanning electron microscopy (SEM). Nitrate and nitrite reduction were performed by an electrochemical method under potentiostatic conditions. The Ppy/Cu electrodes prepared in the oxalate buffer and salicylic acid solutions perform more stable catalytic activity for nitrate reduction; their service life is about ten times longer than that for the electrodes prepared in oxalic acid solution. After 20 h of electrolysis, the nitrite was reduced completely with 100% efficiency and the nitrate was reduced with 35% efficiency. Report submitted to the 5th International Workshop on Advanced Materials Science and Nanotechnology IWAMSN, Hanoi, 9-12 November 2010.

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

    Science.gov (United States)

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

    2016-04-25

    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.

  2. Catalysis of nitrite generation from nitroglycerin by glyceraldehyde-3-phosphate dehydrogenase (GAPDH).

    Science.gov (United States)

    Seabra, Amedea B; Ouellet, Marc; Antonic, Marija; Chrétien, Michelle N; English, Ann M

    2013-11-30

    Vascular relaxation to nitroglycerin (glyceryl trinitrate; GTN) requires its bioactivation by mechanisms that remain controversial. We report here that glyceraldehyde-3-phosphate dehydrogenase (GAPDH) catalyzes the release of nitrite from GTN. In assays containing dithiothreitol (DTT) and NAD(+), the GTN reductase activity of purified GAPDH produces nitrite and 1,2-GDN as the major products. A vmax of 2.6nmolmin(-)(1)mg(-)(1) was measured for nitrite production by GAPDH from rabbit muscle and a GTN KM of 1.2mM. Reductive denitration of GTN in the absence of DTT results in dose- and time-dependent inhibition of GAPDH dehydrogenase activity. Disulfiram, a thiol-modifying drug, inhibits both the dehydrogenase and GTN reductase activity of GAPDH, while DTT or tris(2-carboxyethyl)phosphine reverse the GTN-induced inhibition. Incubation of intact human erythrocytes or hemolysates with 2mM GTN for 60min results in 50% inhibition of GAPDH's dehydrogenase activity, indicating that GTN is taken up by these cells and that the dehydrogenase is a target of GTN. Thus, erythrocyte GAPDH may contribute to GTN bioactivation.

  3. Effects of Processing Temperature on Color Properties of Dry-Cured Hams Made without Nitrite

    Directory of Open Access Journals (Sweden)

    Giovanni Parolari

    2016-04-01

    Full Text Available Dry cured hams were investigated for their ability to develop red color even at low temperature (3–4 °C and in the absence of added nitrites; results were compared with those obtained from nitrite-free hams made at conventional warm maturing temperatures. Colorimetric parameters (L*, a*, b*, and hue and concentration of the main pigments Zn protoporphyrin IX (ZnPP and heme were measured at three stages of preparation (six, nine, and 12 months, showing that red color was successfully formed at low temperatures, though at a slower rate and less intensively than under warm conditions. Major differences in the pattern of color development were found with the two processing temperatures. While the typical features of an enzyme-dependent mechanism, with a progressive drop in enzyme activity paralleling the synthesis of Zn protoporphyrin IX, were observed at warm temperatures, the same did not occur in cold-made hams, where the enzyme activity was almost unchanged throughout the process. These results, along with data from a descriptive sensory analysis, are supportive of a non-enzymatic mechanism leading to ZnPP (hence the red color under cold conditions, with an estimated three-month delay compared with nitrite-free hams manufactured in a warm maturing regimen.

  4. Evaluation of Nitrite Radical Scavenging Properties of Selected Zimbabwean Plant Extracts and Their Phytoconstituents

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    Fadzai Boora

    2014-01-01

    Full Text Available Oxidative stress resulting from accumulation of reactive oxygen species has been associated with disease. The search for natural antioxidants of plant origin is necessitated by the side effects associated with synthetic antioxidants currently available. The objective of the study was to determine the antioxidant activity of Combretum zeyheri, Combretum platypetalum, and Parinari curatellifolia extracts by determining nitrite radical scavenging ability. The nitrite radical scavenging assay was used to evaluate the antioxidant potential of the extracts. The total flavonoid content of P. curatellifolia methanol extract was determined by the aluminium calorimetric method. The aqueous and ethanolic leaf extracts of C. zeyheri, C. platypetalum, and P. curatellifolia extracts exhibited nitrite radical scavenging activity. The results show the scavenging activity in the order of potency: P. curatellifolia > C. platypetalum > C. zeyheri with concentration values of 103 µg/mL, 158 µg/mL, and 188 µg/mL for the ethanol extracts and 92.5 µg/mL, 97.5 µg/mL, and 198 µg/mL for the water extracts, respectively. P. curatellifolia ethanol extract was the most potent and the total flavonoid content was estimated to be 0.4 ± 0.05 mg/g quercetin and could account for the activity. Thus, our findings provide evidence that C. zeyheri, C. platypetalum, and P. curatellifolia leaf extracts could be potential sources of natural antioxidants.

  5. Integrating landfill bioreactors, partial nitritation and anammox process for methane recovery and nitrogen removal from leachate

    Science.gov (United States)

    Sun, Faqian; Su, Xiaomei; Kang, Tingting; Wu, Songwei; Yuan, Mengdong; Zhu, Jing; Zhang, Xiayun; Xu, Fang; Wu, Weixiang

    2016-06-01

    A new process consisting of a landfill bioreactor, partial-nitritation (PN) and the anammox process has been developed for landfill leachate treatment. In this study, the landfill bioreactor exhibited excellent performance in methane-rich biogas recovery, with a specific biogas yield of 0.47 L gas g-1 COD and methane percentages of 53-76%. PN was achieved in the aerobic reactor by high free ammonia (101 ± 83 mg NH3 L-1) inhibition for nitrite-oxidizing bacteria, and the desired PN effluent composition (effluent nitrite: ammonium ratio of 1.1 ± 0.3) was controlled by adjusting the alkalinity concentration per unit of ammonium oxidized to approximately 14.3 mg CaCO3 mg-1 N in the influent. The startup of anammox process was successfully achieved with a membrane bioreactor in 160 d, and a maximum nitrogen removal rate of 216 mg N L-1 d-1 was attained for real landfill leachate treatment. The quantitative polymerase chain reaction results confirmed that the cell-specific anammox activity was approximately 68-95 fmol N cell-1 d-1, which finally led to the stable operation of the system.

  6. Gibberellic acid nitrite stimulates germination of two species of light-requiring seeds via the nitric oxide pathway.

    Science.gov (United States)

    Jovanović, Vladan; Giba, Zlatko; Djoković, Dejan; Milosavljević, Slobodan; Grubisić, Dragoljub; Konjević, Radomir

    2005-06-01

    We used two species of light-requiring seeds, Paulownia tomentosa, which have absolute light requirement (no germination in darkness), and Stellaria media seeds, which germinate in darkness to a certain extent because of presence of preformed active phytochrome, to obtain results strongly suggesting that gibberellic acid nitrite stimulates seed germination via its capability as a functional NO donor. Exogenous application of gibberellic acid nitrite stimulates gibberellin-insensitive Stellaria media seed germination in darkness as do a wide variety of NO donors. Pure gibberellic acid could replace the light requirement of P. tomentosa seeds, thus enabling them to germinate in darkness. Gibberellic acid nitrite did not have this effect. A stimulative effect from gibberellic acid nitrite could be detected only after exposure of these seeds to short, 10 min, pulse of red light. Taken together, these results suggest that gibberellic activity of gibberellic acid nitrite is lost after nitrosation but, regarding to the presence of -O-NO moiety in the molecule, gibberellic acid nitrite shares stimulative properties in seed germination with other compounds with NO-releasing properties.

  7. The role of red blood cell S-nitrosation in nitrite bioactivation and its modulation by leucine and glucose

    Directory of Open Access Journals (Sweden)

    Nadeem Wajih

    2016-08-01

    Full Text Available Previous work has shown that red blood cells (RBCs reduce nitrite to NO under conditions of low oxygen. Strong support for the ability of red blood cells to promote nitrite bioactivation comes from using platelet activation as a NO-sensitive process. Whereas addition of nitrite to platelet rich plasma in the absence of RBCs has no effect on inhibition of platelet activation, when RBCs are present platelet activation is inhibited by an NO-dependent mechanism that is potentiated under hypoxia. In this paper, we demonstrate that nitrite bioactivation by RBCs is blunted by physiologically-relevant concentrations of nutrients including glucose and the important signaling amino acid leucine. Our mechanistic investigations demonstrate that RBC mediated nitrite bioactivation is largely dependent on nitrosation of RBC surface proteins. These data suggest a new expanded paradigm where RBC mediated nitrite bioactivation not only directs blood flow to areas of low oxygen but also to areas of low nutrients. Our findings could have profound implications for normal physiology as well as pathophysiology in a variety of diseases including diabetes, sickle cell disease, and arteriosclerosis.

  8. The Nitrite-Scavenging Properties of Catechol, Resorcinol, and Hydroquinone: A Comparative Study on Their Nitration and Nitrosation Reactions.

    Science.gov (United States)

    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 NO2 group at the hydroxyl oxygen, and resorcinol was nitrosated with 2 NO groups at the C2 and C4 (or C6 ) positions of the benzene ring. Hydroquinone could scavenge nitrite through both nitration and nitrosation mechanisms. The nitrated hydroquinone had 1 NO2 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.

  9. Correlation of low levels of nitrite and high levels of fetal hemoglobin in patients with sickle cell disease at baseline

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    Darcielle Bruna Dias Elias

    2012-01-01

    Full Text Available BACKGROUND: Sickle cell disease is a hemoglobinopathy characterized by hemolytic anemia, increased susceptibility to infections and recurrent vaso-occlusive crises that reduces the quality of life of sufferers. OBJECTIVE: To evaluate the correlation of the levels of lactate dehydrogenase, malonaldehyde and nitrite to fetal hemoglobin in patients with sickle cell disease not under treatment with hydroxyurea in outpatients at a university hospital in Fortaleza, Ceará, Brazil. METHODS: Forty-four patients diagnosed with sickle cell disease were enrolled at baseline. Diagnosis was confirmed by evaluating the beta globin gene using polymerase chain reaction-restriction fragment length polymorphism. The concentration of fetal hemoglobin was obtained by high-performance liquid chromatography. Serum levels of nitrite, malonaldehyde and lactate dehydrogenase were measured by biochemical methods. RESULTS: Significantly higher levels of lactate dehydrogenase, nitrite and malonaldehyde were observed in patients with sickle cell disease compared to a control group. The study of the correlation between fetal hemoglobin levels and these variables showed a negative correlation with nitrite levels. No correlation was found between fetal hemoglobin and malonaldehyde or lactate dehydrogenase. When the study population was stratified according to fetal hemoglobin levels, a decrease in the levels of nitrite was observed with higher levels of fetal hemoglobin (p-value = 0.0415. CONCLUSION: The results show that, similar to fetal hemoglobin levels, the concentration of nitrite can predict the clinical course of the disease, but should not be used alone as a modulator of prognosis in patients with sickle cell disease.

  10. Nitrites, nitrates and N-nitrosoamines in Estonian cured meat products: intake by Estonian children and adolescents.

    Science.gov (United States)

    Reinik, M; Tamme, T; Roasto, M; Juhkam, K; Jurtsenko, S; Tenńo, T; Kiis, A

    2005-11-01

    The contents of nitrate, nitrite and N-nitrosoamines in commercial cured meat products on the Estonian market were determined for 2000-01 and 2003-04 as part of the Estonian food safety monitoring programme and the Estonian Science Foundation grant research activities. The maximum permitted levels of residual nitrites and nitrates were not exceeded in the samples analysed. However, a great variation in the content of nitrate, nitrite and N-nitrosoamines was found for all the products. The concentrations of these compounds in domestic cured meat products showed a decrease from year to year. The mean intake of nitrate, nitrite and N-nitrosoamines by Estonian children (n=346) from cured meat products was calculated on the basis of individual intake data. The mean daily intake of nitrates was 1.7 mg, that of nitrites was 0.83 mg and that of N-nitrosoamines was 0.073 microg. In the 2000-01 study, the calculated nitrite intake exceeded the acceptable daily intake by up to 140% for 1-6-year-old children and up to 105% in 2003-04.

  11. Migration of nitrate, nitrite, and ammonia through the municipal solid waste incinerator bottom ash layer in the simulated landfill.

    Science.gov (United States)

    Yao, Jun; Chen, Luxi; Zhu, Huayue; Shen, Dongsheng; Qiu, Zhanhong

    2017-03-09

    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.

  12. An observational prospective study of topical acidified nitrite for killing methicillin-resistant Staphylococcus aureus (MRSA in contaminated wounds

    Directory of Open Access Journals (Sweden)

    Ferguson Gail P

    2011-10-01

    Full Text Available Abstract Background Endogenous nitric oxide (NO kills bacteria and other organisms as part of the innate immune response. When nitrite is exposed to low pH, NO is generated and has been used as an NO delivery system to treat skin infections. We demonstrated eradication of MRSA carriage from wounds using a topical formulation of citric acid (4.5% and sodium nitrite (3% creams co-applied for 5 days to 15 wounds in an observational prospective pilot study of 8 patients. Findings Following treatment with topical citric acid and sodium nitrite, 9 of 15 wounds (60% and 3 of 8 patients (37% were cleared of infection. MRSA isolates from these patients were all sensitive to acidified nitrite in vitro compared to methicillin-sensitive S. aureus and a reference strain of MRSA. Conclusions Nitric oxide and acidified nitrite offer a novel therapy for control of MRSA in wounds. Wounds that were not cleared of infection may have been re-contaminated or the bioavailability of acidified nitrite impaired by local factors in the tissue.

  13. Optimization of Fermentation Media for Enhancing Nitrite-oxidizing Activity by Artificial Neural Network Coupling Genetic Algorithm

    Institute of Scientific and Technical Information of China (English)

    罗剑飞; 林炜铁; 蔡小龙; 李敬源

    2012-01-01

    Two artificial intelligence techniques, artificial neural network and genetic algorithm, were applied to optimize the fermentation medium for improving the nitrite oxidization rate of nitrite oxidizing bacteria. Experiments were conducted with the composition of medium components obtained by genetic algorithm, and the experimental data were used to build a BP (back propagation) neural network model. The concentrations of six medium components were used as input vectors, and the nitrite oxidization rate was used as output vector of the model. The BP neural network model was used as the objective function of genetic algorithm to find the optimum medium composition for the maximum nitrite oxidization rate. The maximum nitrite oxidization rate was 0.952 g 2 NO-2-N·(g MLSS)-1·d-1 , obtained at the genetic algorithm optimized concentration of medium components (g·L-1 ): NaCl 0.58, MgSO 4 ·7H 2 O 0.14, FeSO 4 ·7H 2 O 0.141, KH 2 PO 4 0.8485, NaNO 2 2.52, and NaHCO 3 3.613. Validation experiments suggest that the experimental results are consistent with the best result predicted by the model. A scale-up experiment shows that the nitrite degraded completely after 34 h when cultured in the optimum medium, which is 10 h less than that cultured in the initial medium.

  14. Nitrite inhalant use among young gay and bisexual men in Vancouver during a period of increasing HIV incidence

    Directory of Open Access Journals (Sweden)

    Mattheis Kelly

    2007-03-01

    Full Text Available Abstract Background Nitrite inhalants ("poppers" are peripheral vasodilators which, since the beginning of the epidemic, have been known to increase risk for acquiring HIV infection among men who have sex with men (MSM. However, few studies in recent years have characterized use. From 1999 to 2004, new HIV diagnoses among MSM in British Columbia increased 78%, prompting us to examine the prevalence and correlates of this modifiable HIV risk factor. Methods Self-administered questionnaires were completed between October 2002 and May 2004 as part of an open cohort study of HIV-seronegative young MSM. We measured nitrite inhalant use during the previous year and use during sexual encounters with casual partners specifically. Correlates of use were identified using odds ratios. Results Among 354 MSM surveyed, 31.6% reported any use during the previous year. Nitrite inhalant use during sexual encounters was reported by 22.9% of men and was strongly associated with having casual partners, with greater numbers of casual partners (including those with positive or unknown serostatus and with anal intercourse with casual partners. Nitrite inhalant use was not associated with non-use of condoms with casual sexual partners per se. Conclusion Contemporary use of nitrite inhalants amongst young MSM is common and a strong indicator of anal intercourse with casual sexual partners. Since use appears to increase the probability of infection following exposure to HIV, efforts to reduce the use of nitrite inhalants among MSM should be a very high priority among HIV prevention strategies.

  15. The impact of nitrite and antioxidants on ultraviolet-A-induced cell death of human skin fibroblasts.

    Science.gov (United States)

    Opländer, Christian; Cortese, Miriam M; Korth, Hans-Gert; Kirsch, Michael; Mahotka, Csaba; Wetzel, Wiebke; Pallua, Norbert; Suschek, Christoph V

    2007-09-01

    Nitrite (NO(2)(-)) occurs ubiquitously in biological fluids such as blood and sweat. Ultraviolet A-induced nitric oxide formation via decomposition of cutaneous nitrite, accompanied by the production of reactive oxygen (ROS) or nitrogen species (RNS), represents an important source for NO in human skin physiology. Examining the impact of nitrite and the antioxidants glutathione (GSH), Trolox (TRL), and ascorbic acid (ASC) on UVA-induced toxicity of human skin fibroblasts (FB) we found that NO(2)(-) concentration-dependently enhances the susceptibility of FB to the toxic effects of UVA by a mechanism comprising enhanced induction of lipid peroxidation. While ASC completely protects FB cultures from UVA/NO(2)(-)-induced cell damage, GSH or TRL excessively enhances UVA/NO(2)(-)-induced cell death by a mechanism comprising nitrite concentration-dependent TRL radical formation or GSH-derived oxidative stress. Simultaneously, in the presence of GSH or TRL the mode of UVA/NO(2)(-)-induced cell death changes from apoptosis to necrosis. In summary, during photodecomposition of nitrite, ROS or RNS formation may act as strong toxic insults. Although inhibition of oxidative stress by NO and other antioxidants represents a successful strategy for protection from UVA/NO(2)(-)-induced injuries, GSH and TRL may nitrite-dependently aggravate the injurious impact by TRL or GSH radical formation, respectively.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Lefevre, Sjannie, E-mail: sjannie.lefevre@biology.au.dk [Zoophysiology, Department of Biological Sciences, Aarhus University, Aarhus (Denmark); Jensen, Frank B. [Department of Biology, University of Southern Denmark, Odense (Denmark); Huong, Do.T.T. [College of Aquaculture and Fisheries, Can Tho University, Can Tho City (Viet Nam); Wang, Tobias [Zoophysiology, Department of Biological Sciences, Aarhus University, Aarhus (Denmark); Phuong, Nguyen T. [College of Aquaculture and Fisheries, Can Tho University, Can Tho City (Viet Nam); Bayley, Mark [Zoophysiology, Department of Biological Sciences, Aarhus University, Aarhus (Denmark)

    2011-07-15

    In this study we investigated nitrite (NO{sub 2}{sup -}) 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{sub 2max}) and critical swimming speed (U{sub crit}) were also assessed. Striped catfish was highly tolerant to nitrite exposure, as reflected by a 96 h LC{sub 50} 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{sub 2max} and U{sub 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{sub 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.

  19. Relevance of nitrate and nitrite in dry-cured ham and their effects on aroma development

    Directory of Open Access Journals (Sweden)

    Flores, Mónica

    2009-07-01

    Full Text Available Potassium and sodium salts of nitrite (E 249 and E 250 and nitrate (E 251 and E 252 are authorised for use under certain levels in several foodstuffs such as non-heat-treated, cured and dried meat products, other cured meat products, canned meat products and bacon. The key point in the use of nitrate and nitrite as preservatives is to find a balance between ensuring the microbiological safety of the ham and keeping as low as possible the level of nitrosamines in the final product. Nitrites and nitrates are authorised as additives for dry-cured ham in the Directive 2006/52/EC of 5 July 2006 that modifies previous Council Directive 95/2/EC on food additives other than colours and sweeteners. The effect of nitrate and its reduction to nitrite in controlling the lipid oxidation process during the ham ripening is very important for the development of the characteristic cured flavour. The main benefits and drawbacks of the use of nitrites and nitrates in dry-cured ham and how these levels may affect its flavour are discussed in this manuscript.Las sales sódica y potásica del nitrito (E249 y E250 y del nitrato (E251 y E252 están autorizados para su uso en los productos cárnicos, secos, curados y no tratados por el calor, otros productos cárnicos curados, productos cárnicos enlatados y bacon. El punto esencial en el uso de nitrato y nitrito como conservantes consiste en encontrar un balance entre el aseguramiento de la seguridad microbiológica del jamón y mantener el nivel de nitrosaminas tan bajo como sea posible. Los nitratos y nitritos están autorizados como aditivos en el jamón curado según la Directiva Europea 2006/52/EC de 5 de Julio de 2006 que modificaba la previa Directiva Europea 95/2/EC de aditivos alimentarios distintos a los colorantes y edulcorantes. El efecto del nitrato y su reducción a nitrito para controlar la oxidación de los lípidos durante la maduración del jamón es muy importante para el desarrollo del caracter

  20. Conserved Active Site Residues Limit Inhibition of a Copper-Containing Nitrite By Small Molecules

    Energy Technology Data Exchange (ETDEWEB)

    Tocheva, E.I.; Eltis, L.D.; Murphy, M.E.P.

    2009-05-26

    The interaction of copper-containing dissimilatory nitrite reductase from Alcaligenes faecalis S-6 ( AfNiR) with each of five small molecules was studied using crystallography and steady-state kinetics. Structural studies revealed that each small molecule interacted with the oxidized catalytic type 2 copper of AfNiR. Three small molecules (formate, acetate and nitrate) mimic the substrate by having at least two oxygen atoms for bidentate coordination to the type 2 copper atom. These three anions bound to the copper ion in the same asymmetric, bidentate manner as nitrite. Consistent with their weak inhibition of the enzyme ( K i >50 mM), the Cu-O distances in these AfNiR-inhibitor complexes were approximately 0.15 A longer than that observed in the AfNiR-nitrite complex. The binding mode of each inhibitor is determined in part by steric interactions with the side chain of active site residue Ile257. Moreover, the side chain of Asp98, a conserved residue that hydrogen bonds to type 2 copper-bound nitrite and nitric oxide, was either disordered or pointed away from the inhibitors. Acetate and formate inhibited AfNiR in a mixed fashion, consistent with the occurrence of second acetate binding site in the AfNiR-acetate complex that occludes access to the type 2 copper. A fourth small molecule, nitrous oxide, bound to the oxidized metal in a side-on fashion reminiscent of nitric oxide to the reduced copper. Nevertheless, nitrous oxide bound at a farther distance from the metal. The fifth small molecule, azide, inhibited the reduction of nitrite by AfNiR most strongly ( K ic = 2.0 +/- 0.1 mM). This ligand bound to the type 2 copper center end-on with a Cu-N c distance of approximately 2 A, and was the only inhibitor to form a hydrogen bond with Asp98. Overall, the data substantiate the roles of Asp98 and Ile257 in discriminating substrate from other small anions.

  1. Control of H2S emission from swine manure using Na-nitrite and Na-molybdate.

    Science.gov (United States)

    Predicala, Bernardo; Nemati, Mehdi; Stade, Sarah; Laguë, Claude

    2008-06-15

    Biogenic production of hydrogen sulphide (H2S) in oil reservoirs (souring) has been shown to be controlled effectively using nitrite and molybdate salts. In the present work the effects of addition of nitrite and molybdate on reducing the emission of H2S from swine manure slurry was investigated in the laboratory and semi-pilot scale systems. Addition of 80 mM nitrite or 2 mM molybdate (final concentration in the manure slurry) to fresh manure in the laboratory scale closed systems (125 mL and 4 L) reduced the concentration of H2S in the headspace gas from 1500 microL L(-1) to 10 microL L(-1) which maintained during the remaining period of trials (40-60 days). With aged manure, similar results were achieved with a lower level of nitrite (10 mM). Simultaneous or sequential additions of nitrite and molybdate to fresh manure had similar effects. Contrary to the systems simulating biological conditions in oil reservoirs in which simultaneous addition of nitrite and molybdate has been reported to have a synergistic effect, no synergism was observed when nitrite and molybdate were added to the manure simultaneously. Experiments with fresh manure slurry in the semi-pilot scale systems (200 L) confirmed the effectiveness of this approach in which addition of 80 mM nitrite or 2 mM molybdate or a combination of 80 mM nitrite and 2 mM molybdate decreased the concentration of the H2S in the headspace gas from an initial value of 500 microL L(-1) to a low level in the range 2-25 microL L(-1) and maintained these low levels during the remaining period of trials (16 days). The concentration of ammonia (NH3) in the headspace gas of the treated systems was similar to that observed in the control system (untreated), indicating that the treatment did not have an effect on the level of present NH3. Although the addition of nitrite or molybdate reduced emissions of H2S from swine manure and the associated health and safety concerns, it had little impact on the intensity of odour in the

  2. Research Progress of Meat Product with Low Nitrite%低硝肉制品研究进展

    Institute of Scientific and Technical Information of China (English)

    孙迪; 张志国

    2016-01-01

    Nitrite is a common kind of food additive.In meat production,nitrite is responsible for the development of cured color,flavor and texture of meat products.More importantly,nitrite acts as a strong antimicrobial agent to control Clostridium botulinum outgrowth.But nitrite is responsible for the issues concerning the safety of using nitrite for cured meat,which include chemical toxicity and formation of N-nitrosamines.Therefore,research on the problems of nitrite substitute is urgent. Summarize the important role of nitrite in meat products and safety problems;also introduce the research progress of low-nitrite meat product,especially the research progress of antibacterial activity of nitrite,and the development prospect of low-nitrite meat product.%亚硝酸盐是一种常用的食品添加剂,在肉制品加工中,亚硝酸盐具有发色、呈味及改善肉制品质构的作用,更为重要的是对肉毒梭状芽孢杆菌有抑制作用。但亚硝酸盐性质活泼,添加过量可引起中毒,同时又能与胺类物质生成强致癌物亚硝胺。因此,亚硝酸盐替代物的研究问题亟待解决。文章总结了亚硝酸盐在肉制品中的重要作用及其带来的安全性问题,同时介绍了低硝肉制品的研究进展,尤其是亚硝酸盐抑菌作用的研究进展,还对低硝肉制品的发展前景做了展望。

  3. 芜湖市几种常见蔬菜中亚硝酸盐含量分析%Nitrite content of common vegetables in Wuhu City

    Institute of Scientific and Technical Information of China (English)

    王友保; 黄伟; 刘登义

    2005-01-01

    Laboratory analysis was carried out to study the nitrite content and its affecting factors of 10 common vegetables in terminal markets of Wuhu City. The results showed that the nitrite content of root or stem-and fruit vegetables was lower than the national standard, but that of leaf vegetables exceeded the standard seriously. The nitrite in vegetables increased significantly with storage time. Stored under room temperature, the test vegetables had 1~2 times higher nitrite content at the fourth day than at the first day, but storage under low temperature, i. e., in refrigerator, could hinder the increase of nitrite content in vegetables, and the daily increase was only 1/2 ~ 1/6 times of that under room temperature. Abluent could eliminate nitrite effectively, whose efficiency was 1~5 times higher than that of tap water.

  4. Shifts between Nitrospira- and Nitrobacter-like nitrite oxidizers underlie the response of soil potential nitrite oxidation to changes in tillage practices.

    Science.gov (United States)

    Attard, E; Poly, F; Commeaux, C; Laurent, F; Terada, A; Smets, B F; Recous, S; Roux, X Le

    2010-02-01

    Despite their role in soil functioning, the ecology of nitrite-oxidizing bacteria, NOB, and their response to disturbances such as those generated by agricultural practices are scarcely known. Over the course of 17 months, we surveyed the potential nitrite oxidation, PNO, the abundance of the Nitrobacter- and Nitrospira-like NOB (by quantitative PCR) and the community structure of the Nitrobacter-like NOB (by PCR-DGGE and cloning-sequencing targeting the nxrA gene) in soils for four treatments: after establishment of tillage on a previously no-tillage system, after cessation of tillage on a previously tillage system, and on control tillage and no-tillage systems. Key soil variables (moisture, organic carbon content and gross mineralization--i.e. ammonification--measured by the 15N dilution technique) were also surveyed. PNO was always higher for the no-tillage than tillage treatments. Establishment of tillage led to a strong and rapid decrease in PNO whereas cessation of tillage did not change PNO even after 17 months. PNO was strongly and positively correlated to the abundance of Nitrobacter-like NOB and was also strongly related to gross mineralization, a proxy of N-availability; in contrast, PNO was weakly and negatively correlated to the abundance of Nitrospira-like NOB. Selection of a dominant population was observed under no-tillage, and PNO was loosely correlated to the community structure of Nitrobacter-like NOB. Our results demonstrate that Nitrobacter-like NOB are the key functional players within the NOB community in soils with high N availability and high activity level, and that changes in PNO are due to shifts between Nitrospira-like and Nitrobacter-like NOB and to a weaker extent by shifts of populations within Nitrobacter-like NOB.

  5. Nitrite and Nitrate Levels of Gingival Crevicular Fluid and Saliva in Subjects with Gingivitis and Chronic Periodontitis

    Directory of Open Access Journals (Sweden)

    Ali Orkun Topcu

    2014-07-01

    Full Text Available Objectives: Nitrosative stress plays an essential role in the pathogenesis of periodontal disease. The aim of this study is to analyze the gingival crevicular fluid and saliva nitrite and nitrate levels in periodontally healthy and diseased sites. Material and Methods: A total of 60 individuals including, 20 chronic periodontitis and 20 gingivitis patients and 20 periodontally healthy controls participated in the present study. Probing depth, clinical attachment level, bleeding on probing, gingival index and plaque index were assessed, gingival crevicular fluid (GCF and saliva samples were obtained from the subjects, including 480 GCF samples and 60 unstimulated whole saliva samples. Nitrite and nitrate were analyzed by Griess reagent. Results: Total GCF nitrite levels were higher in gingivitis and periodontitis groups (1.07 [SD 0.62] nmol and 1.08 [SD 0.59] nmol than the control group (0.83 [SD 0.31] nmol (P 0.05. The difference in GCF nitrate level was not significant among the control, gingivitis and periodontitis groups (7.7 [SD 2.71] nmol, 7.51 [SD 4.16] nmol and 7.38 [SD 1.91] nmol. Saliva nitrite and nitrate levels did not differ significantly among three study groups. Saliva nitrate/nitrite ratios were higher in periodontitis and gingivitis groups than the control group. A gradual decrease in nitrate/nitrite ratio in GCF was detected with the presence of inflammation. Conclusions: It may be suggested that nitrite in gingival crevicular fluid is a better periodontal disease marker than nitrate and may be used as an early detection marker of periodontal inflammation, and that local nitrosative stress markers don’t show significant difference between the initial and advanced stages of periodontal disease.

  6. Sarcoplasmic phospholamban protein is involved in the mechanisms of postresuscitation myocardial dysfunction and the cardioprotective effect of nitrite during resuscitation.

    Directory of Open Access Journals (Sweden)

    Yu Huang

    Full Text Available OBJECTIVES: Sarcoplasmic reticulum (SR Ca(2+-handling proteins play an important role in myocardial dysfunction after acute ischemia/reperfusion injury. We hypothesized that nitrite would improve postresuscitation myocardial dysfunction by increasing nitric oxide (NO generation and that the mechanism of this protection is related to the modulation of SR Ca(2+-handling proteins. METHODS: We conducted a randomized prospective animal study using male Sprague-Dawley rats. Cardiac arrest was induced by intravenous bolus of potassium chloride (40 µg/g. Nitrite (1.2 nmol/g or placebo was administered when chest compression was started. No cardiac arrest was induced in the sham group. Hemodynamic parameters were monitored invasively for 90 minutes after the return of spontaneous circulation (ROSC. Echocardiogram was performed to evaluate cardiac function. Myocardial samples were harvested 5 minutes and 1 hour after ROSC. RESULTS: Myocardial function was significantly impaired in the nitrite and placebo groups after resuscitation, whereas cardiac function (i.e., ejection fraction and fractional shortening was significantly greater in the nitrite group than in the placebo group. Nitrite administration increased the level of nitric oxide in the myocardium 5 min after resuscitation compared to the other two groups. The levels of phosphorylated phospholamban (PLB were decreased after resuscitation, and nitrite increased the phosphorylation of phospholamban compared to the placebo. No significant differences were found in the expression of sarcoplasmic reticulum Ca(2+ ATPase (SERCA2a and ryanodine receptors (RyRs. CONCLUSIONS: postresuscitation myocardial dysfunction is associated with the impairment of PLB phosphorylation. Nitrite administered during resuscitation improves postresuscitation myocardial dysfunction by preserving phosphorylated PLB protein during resuscitation.

  7. Effect of sodium nitrite on ischaemia and reperfusion-induced arrhythmias in anaesthetized dogs: is protein S-nitrosylation involved?

    Directory of Open Access Journals (Sweden)

    Mária Kovács

    Full Text Available To provide evidence for the protective role of inorganic nitrite against acute ischaemia and reperfusion-induced ventricular arrhythmias in a large animal model.Dogs, anaesthetized with chloralose and urethane, were administered intravenously with sodium nitrite (0.2 µmol kg(-1 min(-1 in two protocols. In protocol 1 nitrite was infused 10 min prior to and during a 25 min occlusion of the left anterior descending (LAD coronary artery (NaNO2-PO; n = 14, whereas in protocol 2 the infusion was started 10 min prior to reperfusion of the occluded vessel (NaNO2-PR; n = 12. Control dogs (n = 15 were infused with saline and subjected to the same period of ischaemia and reperfusion. Severities of ischaemia and ventricular arrhythmias, as well as changes in plasma nitrate/nitrite (NOx levels in the coronary sinus blood, were assessed throughout the experiment. Myocardial superoxide and nitrotyrosine (NT levels were determined during reperfusion. Changes in protein S-nitrosylation (SNO and S-glutathionylation were also examined.Compared with controls, sodium nitrite administered either pre-occlusion or pre-reperfusion markedly suppressed the number and severity of ventricular arrhythmias during occlusion and increased survival (0% vs. 50 and 92% upon reperfusion. There were also significant decreases in superoxide and NT levels in the nitrite treated dogs. Compared with controls, increased SNO was found only in NaNO2-PR dogs, whereas S-glutathionylation occurred primarily in NaNO2-PO dogs.Intravenous infusion of nitrite profoundly reduced the severity of ventricular arrhythmias resulting from acute ischaemia and reperfusion in anaesthetized dogs. This effect, among several others, may result from an NO-mediated reduction in oxidative stress, perhaps through protein SNO and/or S-glutathionylation.

  8. 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.

    Science.gov (United States)

    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

  9. Urinary nitrite/nitrate ratio measured by isotope-dilution LC-MS/MS as a tool to screen for urinary tract infections.

    Science.gov (United States)

    Chao, Mu-Rong; Shih, Ying-Ming; Hsu, Yu-Wen; Liu, Hung-Hsin; Chang, Yuan-Jhe; Lin, Bo-Huei; Hu, Chiung-Wen

    2016-04-01

    Urinary tract infections (UTIs) are the most common type of nosocomial infection. Traditionally, the presence of white blood cells and microorganisms in the urine provides objective evidence for UTI diagnosis. Here, we describe the use of liquid chromatography-tandem mass spectrometry (LC-MS/MS) to measure the nitrite and nitrate levels in urine and investigate the potential of this method for UTI diagnosis. LC-MS/MS analysis was performed in positive electrospray ionization mode. After adding (15)N-labeled internal standards and derivatizing with 2,3-diaminonaphthalene (DAN), the urinary nitrite content was directly analyzed by LC-MS/MS, whereas the urinary nitrate was first reduced to nitrite before derivatization and LC-MS/MS analysis. The derivatization of nitrite and enzymatic reduction of nitrate were optimized. This method was then applied to 241 healthy subjects and 73 UTI patients. Optimization tests revealed that 1 mL of crude urine required at least 6.25 μmol of DAN to completely derivatize nitrite and 2.5 U of nitrate reductase to completely reduce nitrate to nitrite. Urinary analysis showed that the urinary concentration of nitrite and the nitrite/nitrate ratio were higher in UTI patients than in healthy subjects. Compared with the dipstick-based urinary nitrite test and using LC-MS/MS to determine the nitrite concentration (sensitivity: 23-25%), the nitrite/nitrate ratio was significantly more sensitive (95%) and exhibited a satisfactory specificity (91%) in the screening of UTIs. Taken together, the nitrite/nitrate ratio, which reflects the reducing ability of pathogenic bacteria, could be a better method for the diagnosis of UTIs that is not subject to variations in urine specimen quality.

  10. Serial crystallography captures enzyme catalysis in copper nitrite reductase at atomic resolution from one crystal.

    Science.gov (United States)

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

    2016-07-01

    Relating individual protein crystal structures to an enzyme mechanism remains a major and challenging goal for structural biology. Serial crystallography using multiple crystals has recently been reported in both synchrotron-radiation and X-ray free-electron laser experiments. In this work, serial crystallography was used to obtain multiple structures serially from one crystal (MSOX) to study in crystallo enzyme catalysis. Rapid, shutterless X-ray detector technology on a synchrotron MX beamline was exploited to perform low-dose serial crystallography on a single copper nitrite reductase crystal, which survived long enough for 45 consecutive 100 K X-ray structures to be collected at 1.07-1.62 Å resolution, all sampled from the same crystal volume. This serial crystallography approach revealed the gradual conversion of the substrate bound at the catalytic type 2 Cu centre from nitrite to nitric oxide, following reduction of the type 1 Cu electron-transfer centre by X-ray-generated solvated electrons. Significant, well defined structural rearrangements in the active site are evident in the series as the enzyme moves through its catalytic cycle, namely nitrite reduction, which is a vital step in the global denitrification process. It is proposed that such a serial crystallography approach is widely applicable for studying any redox or electron-driven enzyme reactions from a single protein crystal. It can provide a 'catalytic reaction movie' highlighting the structural changes that occur during enzyme catalysis. The anticipated developments in the automation of data analysis and modelling are likely to allow seamless and near-real-time analysis of such data on-site at some of the powerful synchrotron crystallographic beamlines.

  11. The impact of influent total ammonium nitrogen concentration on nitrite-oxidizing bacteria inhibition in moving bed biofilm reactor.

    Science.gov (United States)

    Kouba, Vojtech; Catrysse, Michael; Stryjova, Hana; Jonatova, Ivana; Volcke, Eveline I P; Svehla, Pavel; Bartacek, Jan

    2014-01-01

    The application of nitrification-denitrification over nitrite (nitritation-denitritation) with municipal (i.e. diluted and cold (or low-temperature)) wastewater can substantially improve the energy balance of municipal wastewater treatment plants. For the accumulation of nitrite, it is crucial to inhibit nitrite-oxidizing bacteria (NOB) with simultaneous proliferation of ammonium-oxidizing bacteria (AOB). The present study describes the effect of the influent total ammonium nitrogen (TAN) concentration on AOB and NOB activity in two moving bed biofilm reactors operated as sequencing batch reactors (SBR) at 15 °C (SBR I) and 21 °C (SBR II). The reactors were fed with diluted reject water containing 600, 300, 150 and 75 mg TAN L(-1). The only factor limiting NOB activity in these reactors was the high concentrations of free ammonia and/or free nitrous acid (FNA) during the SBR cycles. Nitrite accumulation was observed with influents containing 600, 300 and 150 mg TAN L(-1) in SBR I and 600 and 300 in SBR II. Once nitrate production established in the reactors, the increase of influent TAN concentration up to the original 600 mg TAN L(-1) did not limit NOB activity. This was due to the massive development of NOB clusters throughout the biofilm that were able to cope with faster formation of FNA. The results of the fluorescence in situ hybridization analysis preliminarily showed the stratification of bacteria in the biofilm.

  12. Nucleotide/Tb³⁺ coordination polymer nanoparticles as luminescent sensor and scavenger for nitrite ion.

    Science.gov (United States)

    Qi, Zewan; You, Qi; Chen, Yang

    2016-01-01

    Newly emerged metal organic coordination polymers have aroused the great interest in designing tailored functional materials. In this study, multiple functional components, luminescent Tb(3+) ion, nucleobase and antenna molecule, were integrated in a single material and prepared into a responsive nanoparticle for nitrite. The terbium coordination polymer nanoparticles made of this kind of material have the dual functions of recognition and transduction and obey a preset sensing mechanism without a post-functionalization of common materials. As the result of the tailored, the terbium coordination polymer nanoparticles are highly sensitive and selective to nitrite by means of Dexter energy transfer between Tb(3+) ion and nitrite, and can be used for the scavenger for nitrite in aqueous solution. The detection limit, dynamic range and removal capacity of U-Tb-OBBA CPNPs for nitrite are 0.3 µM, 0.3-470 µM and 4.44 mg per gram of particles, respectively. Metal organic coordination polymers show an attractive potential in constructing smart sensing materials.

  13. Globin X is a six-coordinate globin that reduces nitrite to nitric oxide in fish red blood cells

    Science.gov (United States)

    Corti, Paola; Xue, Jianmin; Tejero, Jesús; Wajih, Nadeem; Sun, Ming; Stolz, Donna B.; Tsang, Michael; Kim-Shapiro, Daniel B.; Gladwin, Mark T.

    2016-01-01

    The discovery of novel globins in diverse organisms has stimulated intense interest in their evolved function, beyond oxygen binding. Globin X (GbX) is a protein found in fish, amphibians, and reptiles that diverged from a common ancestor of mammalian hemoglobins and myoglobins. Like mammalian neuroglobin, GbX was first designated as a neuronal globin in fish and exhibits six-coordinate heme geometry, suggesting a role in intracellular electron transfer reactions rather than oxygen binding. Here, we report that GbX to our knowledge is the first six-coordinate globin and the first globin protein apart from hemoglobin, found in vertebrate RBCs. GbX is present in fish erythrocytes and exhibits a nitrite reduction rate up to 200-fold faster than human hemoglobin and up to 50-fold higher than neuroglobin or cytoglobin. Deoxygenated GbX reduces nitrite to form nitric oxide (NO) and potently inhibits platelet activation in vitro, to a greater extent than hemoglobin. Fish RBCs also reduce nitrite to NO and inhibit platelet activation to a greater extent than human RBCs, whereas GbX knockdown inhibits this nitrite-dependent NO signaling. The description of a novel, six-coordinate globin in RBCs with dominant electron transfer and nitrite reduction functionality provides new insights into the evolved signaling properties of ancestral heme-globins. PMID:27407144

  14. Behavior of Staphylococcus aureus and autochthone microbiota in fresh sausages added of sodium nitrite and stored under refrigeration

    Directory of Open Access Journals (Sweden)

    Lucyanne Maria Moraes Correia

    2014-10-01

    Full Text Available Fresh sausages are cured meat products that may be contaminated with Staphylococcus aureus during the manufacturing procedure, which is frequently related with inadequate handling practices. The use of nitrite in meat products has proven efficacy against Clostridium botulinum, and studies indicate that bactericidal action against S. aureus depends on factors that are intrinsic and extrinsic to the product. The objective of the present study was to evaluate the effect of nitrite concentration, and pH on S. aureus and psychrotrophic autochthone microbiota in fresh sausages stored at different times and temperatures. Fresh sausage were produced at nitrite concentrations 50, 150 and 200ppm and contaminated with S. aureus. The sausages were storage at refrigeration (7 and 12°C and the quantification of S. aureus and psychrotrophic microorganisms was carried out on days 0, 2, 4, 7, and 10. Results showed that nitrite concentrations and the temperatures used had minimal effect on the multiplication of S. aureus and psychrotrophic autochthone microbiota. Final counts depended only on the length of storage: at the end of 10 days, counts were statistically similar in the different groups, showing that temperature and nitrite concentrations used did not control microbial growth effectively. It is suggested that the product should be stored below 7°C or at freezing temperatures for greater microbiological stability

  15. Simultaneous nitritation-denitritation for the treatment of high-strength nitrogen in hypersaline wastewater by aerobic granular sludge.

    Science.gov (United States)

    Corsino, Santo Fabio; Capodici, Marco; Morici, Claudia; Torregrossa, Michele; Viviani, Gaspare

    2016-01-01

    Fish processing industries produce wastewater containing high amounts of salt, organic matter and nitrogen. Biological treatment of such wastewaters could be problematic due to inhibitory effects exerted by high salinity levels. In detail, high salt concentrations lead to the accumulation of nitrite due to the inhibition of nitrite-oxidizing bacteria. The feasibility of performing simultaneous nitritation and denitritation in the treatment of fish canning wastewater by aerobic granular sludge was evaluated, and simultaneous nitritation-denitritation was successfully sustained at salinities up to 50 gNaCl L(-1), with a yield of over 90%. The total nitrogen concentration in the effluent was less than 10 mg L(-1) at salinities up to 50 gNaCl L(-1). Nitritation collapsed above 50 gNaCl L(-1), and then, the only nitrogen removal mechanism was represented by heterotrophic synthesis. In contrast, organic matter removal was not affected by salinity but was instead affected by the organic loading rate (OLR). Both COD and BOD removal efficiencies were over 90%. The COD fractionation analysis indicated that aerobic granules were able to remove more than 95% of the particulate organic matter. Finally, results obtained in this work noted that aerobic granular sludge had an excellent ability to adapt under adverse environmental conditions.

  16. Formation and mitigation of N-nitrosamines in nitrite preserved cooked sausages

    DEFF Research Database (Denmark)

    Herrmann, Susan Strange; Granby, Kit; Duedahl-Olesen, Lene

    2015-01-01

    ) and N-nitrosopyrrolidine (NPYR) remained at or below limit of quantification. Erythorbic acid inhibited the formation of NHPRO, NPRO, NPIP and NTCA. This inhibition was for NTCA and NMTCA counteracted by addition of free iron. Ascorbyl palmitate had less inhibitory effect than erythorbic acid......-nitrosohydroxyproline (NHPRO), N-nitrosoproline (NPRO), N-nitrosothiazolidine-4-carboxylic acid (NTCA) and N-nitroso-2-methyl-thiazolidine-4-carboxylic acid (NMTCA) and the amount of nitrite added to cooked pork sausages. The levels studied were 0, 60, 100, 150, 250 and 350 mg kg-1. The levels of N-nitrosodimethylamine (NDMA...

  17. Nitrite reduction by a pyridinediimine complex with a proton-responsive secondary coordination sphere.

    Science.gov (United States)

    Kwon, Yubin M; Delgado, Mayra; Zakharov, Lev N; Seda, Takele; Gilbertson, John D

    2016-09-21

    The proton-responsive pyridinediimine ligand, (DEA)PDI (where (DEA)PDI = [(2,6-(i)PrC6H3)(N[double bond, length as m-dash]CMe)(N(Et)2C2H4)(N[double bond, length as m-dash]CMe)C5H3N]) was utilized for the reduction of NO2(-) to NO. Nitrite reduction is facilitated by the protonated secondary coordination sphere coupled with the ligand-based redox-active sites of [Fe(H(DEA)PDI)(CO)2](+) and results in the formation of the {Fe(NO)2}(9) DNIC, [Fe((DEA)PDI)(NO)2](+).

  18. Metal-mediated Multiporphyrin Arrays at Interfaces:Preparation, Electrochemistry, Catalytic Oxidation of Nitrite and NO

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    1 Results Manganese porphyrins have attracted growing interest because of their unique physical and chemical properties,such as mimicking the role of Mn complex in photosystem Ⅱ and acting as electrocatalysts towards the oxidation of nitric oxide and nitrite.As one of the bottom-up techniques,we are currently investigating the design,preparation and opto-electrochemical properties of metal-mediated multiporphyrin arrays on the solid surfaces.Because the porphyrins are connected by metal ions via coordin...

  19. Nitrite residue and malonaldehyde reduction in dendeng--Indonesian dried meat--influenced by spices, curing methods and precooking preparation.

    Science.gov (United States)

    Suryati, T; Astawan, M; Lioe, H N; Wresdiyati, T; Usmiati, S

    2014-03-01

    This research was conducted to reduce nitrite residue and malonaldehyde (MDA) content of dendeng through modifying the formulation of spices, curing technique and precooking preparation. The result showed that spiced fried dendeng was likely to contain high total phenolics and antioxidant activity. Wet cured dendeng combined with spices containing 2.0% coriander and 10.0% garlic and preparation by soaking before frying was effective to produce dendeng that had no detected nitrite residue and low MDA. In conclusion, the spice formulas used in this study could reduce nitrite residue and MDA level of dendeng, and the treatment prior to frying, by soaking the dendeng briefly in water, lowered MDA of non-spiced dendeng, but no effect of soaking was observed in spiced samples due to the very low MDA found in the samples.

  20. Biogenic amine formation and nitrite reactions in meat batter as affected by high-pressure processing and chilled storage.

    Science.gov (United States)

    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 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.

  1. New Mechanism on Synergistic Effect of Nitrite and Triethanolamine Addition on the Corrosion of Ductile Cast Iron

    Directory of Open Access Journals (Sweden)

    K. T. Kim

    2016-01-01

    Full Text Available In general, we compared the different inhibition mechanisms of organic inhibitor with that of anodic inhibitor. When triethanolamine or nitrite was added separately to tap water for inhibiting the corrosion of ductile cast iron, large amounts of inhibitor were needed. This is because the corrosion inhibitors had to overcome the galvanic corrosion that occurs between graphite and matrix. In this work, we investigated the corrosion of ductile cast iron in tap water with/without inhibitors. The corrosion rate was measured using chemical immersion test and electrochemical methods, including anodic polarization test. The inhibited surface was analyzed using EPMA and XPS. Test solutions were analyzed by performing FT-IR measurement. When triethanolamine and nitrite coexisted in tap water, synergistic effect built up, and the inhibition effect was ca. 30 times more effective than witnessed with single addition. This work focused on the synergistic effect brought about by nitrite and triethanolamine and its novel mechanism was also proposed.

  2. Different responses to nitrate and nitrite by the model organism Escherichia coli and the human pathogen Neisseria gonorrhoeae.

    Science.gov (United States)

    Whitehead, R N; Cole, J A

    2006-02-01

    The ability of Escherichia coli to use both nitrate and nitrite as terminal electron acceptors during anaerobic growth is mediated by the dual-acting two-component regulatory systems NarX-NarL and NarQ-NarP. In contrast, Neisseria gonorrhoeae responds only to nitrite: it expresses only NarQ-NarP. We have shown that although N. gonorrhoeae NarQ can phosphorylate E. coli NarL and NarP, the N. gonorrhoeae NarP is unable to regulate gene expression in E. coli. Mutagenesis experiments have revealed residues in E. coli NarQ that are essential for nitrate and nitrite sensing. Chimaeric proteins revealed domains of NarQ that are important for ligand sensing.

  3. Cultivation of a chemoautotroph from the SUP05 clade of marine bacteria that produces nitrite and consumes ammonium

    Science.gov (United States)

    Shah, Vega; Chang, Bonnie X; Morris, Robert M

    2017-01-01

    Marine oxygen minimum zones (OMZs) are expanding regions of intense nitrogen cycling. Up to half of the nitrogen available for marine organisms is removed from the ocean in these regions. Metagenomic studies have identified an abundant group of sulfur-oxidizing bacteria (SUP05) with the genetic potential for nitrogen cycling and loss in OMZs. However, SUP05 have defied cultivation and their physiology remains untested. We cultured, sequenced and tested the physiology of an isolate from the SUP05 clade. We describe a facultatively anaerobic sulfur-oxidizing chemolithoautotroph that produces nitrite and consumes ammonium under anaerobic conditions. Genetic evidence that closely related strains are abundant at nitrite maxima in OMZs suggests that sulfur-oxidizing chemoautotrophs from the SUP05 clade are a potential source of nitrite, fueling competing nitrogen removal processes in the ocean. PMID:27434424

  4. Prebiotic Nitrogen Fixation by FeS Reduction of Nitrite Under Acidic Conditions

    Science.gov (United States)

    Summers, David P.; Mead, Susan C. (Technical Monitor)

    1999-01-01

    Theories for the origin of life require the availability of reduced nitrogen for the formation of such species as amino acid and nucleic acids. In a strongly reducing atmosphere, compounds essential to the chemical evolution of life, such as amino acids, can form by reactions between HCN, NH3, and carbonyl compounds produced in spark discharges. However, under non-reducing atmospheres, electric discharges produced NO rather than HCN or NH3. This raises the questions of; how ammonia can be formed under a neutral atmosphere, and what conditions are needed such formation to occur? On possibility is the conversion of NO into nitric and nitrous acids (through HNO) and rained into the oceans. The reduction of nitrite by aqueous Fe(II) (6 Fe(+2) + 7 H(+) + NO2(-) yields 6 Fe(III) + 2 H2O + NH3) such as was present on the early Earth could then have produced ammonia. However, this reaction does not proceed at pHs less than 7.3. An alternative is reduction by other forms of Fe(II), such as FeS. We will present results that show that FeS can reduce nitrite to ammonia at pHs as low as pH 5 under a variety of conditions.

  5. Hemorheological changes and hematometric erythrocyte characteristics in rats after sodium nitrite intoxication

    Science.gov (United States)

    Ivanov, Ivan; Gluhcheva, Yordanka; Petrova, Emilia; Antonova, Nadia

    2014-05-01

    Sodium nitrite (NaNO2) is a precursor to a variety of organic compounds (pharmaceuticals, dyes and pesticides), but it is best known as a food additive. The aim of the study is to investigate the influence of acute (i.p.) treatment of Wistar rats with NaNO2 (at the dose of 50 mg/kg b.w.) on the blood rheological properties and erythrocyte hematometric indices (Hb, HCT, RBC, MCV, RDW, MCH, MCHC). The significant differences were not found in the whole blood viscosity (WBV) values of the control and NaNO2-treated groups. The changes in the erythrocyte hematometric indices were statistically significant for RDW, MCHC and MCH at the 1st hour, five- and ten days after NaNO2 administration. Interestingly, at the day 5th of the NaNO2 treatment we obtained statistically significant lower values for the RBC count, Hb, HCT, RDW, as well as elevated indices MCV (no statistically significant), MCH, MCHC. The results obtained indicate that hemorheological and hematometric parameters examined should be monitored in cases of acute exposure to nitrites — for the purposes of clinical toxicology. The quantitative values of hematometric indices reported in our experimental model could be suitable for predicting NaNO2 intoxication and methemoglobinemia in animals and humans.

  6. Electrochemical detection of nitrite on poly(pyronin Y)/graphene nanocomposites modified ITO substrate

    Science.gov (United States)

    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.

  7. Influence of ultrasonic waves in the reduction of nitrate to nitrite by hydrazine-Cu(II).

    Science.gov (United States)

    Silva, Luciana A; Korn, Mauro; de Andrade, Jailson B

    2007-02-01

    Colorimetric methods are still important for determining nitrate and nitrite. A critical step in the use of these methods to determine nitrate in low concentrations is the reaction time required to totally reduce nitrate to nitrite, i.e., 24h in the dark. This work involved a study of the influence of ultrasonic irradiation on the nitrate reduction reaction by hydrazine. Our findings indicated that ultrasonic irradiation, associated with copper(II) ion as a catalyst, increased the redox reaction rate, decreasing the reaction time to about 10min when the power of the ultrasonic irradiation was set in 14.0357W. The strong influence of the ultrasonic irradiation in the reduction reaction rates can be sustained by an excellent linear correlation (R(2)=0.9993) between the kinetic constants and ultrasonic powers. Nitrate conversion also increased from 68% to 98% at the latter conditions. It thus become clear that high intensity ultrasound is very beneficial for this reduction reaction to proceed in good yield and in short reaction time in comparison to its silent reaction.

  8. Formation of naturally occurring pigments during the production of nitrite-free dry fermented sausages.

    Science.gov (United States)

    De Maere, Hannelore; Fraeye, Ilse; De Mey, Eveline; Dewulf, Lore; Michiels, Chris; Paelinck, Hubert; Chollet, Sylvie

    2016-04-01

    This study investigates the potential of producing red coloured dry fermented sausages without the addition of nitrite and/or nitrate. Therefore, the formation of zinc protoporphyrin IX (Zn(II)PPIX) as naturally occurring pigment, and the interrelated protoporphyrin IX (PPIX) and heme content were evaluated during nitrite-free dry fermented sausage production at different pH conditions. Zn(II)PPIX was only able to form in dry fermented sausages at pH conditions higher than approximately 4.9. Additionally, the presence of Zn(II)PPIX increased drastically at the later phase of the production process (up to day 177), confirming that in addition to pH, time is also a crucial factor for its formation. Similarly, PPIX also accumulated in the meat products at increased pH conditions and production times. In contrast, a breakdown of heme was observed. This breakdown was more gradual and independent of pH and showed no clear relationship with the formed amounts of Zn(II)PPIX and PPIX. A statistically significant relationship between Zn(II)PPIX formation and product redness was established.

  9. [Amount of nitrate and nitrite in daily menus containing more than 350 g of vegetables].

    Science.gov (United States)

    Murata, Mihoko; Sugiyama, Sumi; Ueda, Aiko; Ishinaga, Masataka

    2010-01-01

    The contents of nitrate and nitrite in menus containing more than 350 g of vegetables per day were investigated. The amounts of vegetables in menu A developed by female students and menu B taken from a recipe book were 350+/-2 g and 457+/-77 g, respectively. The average content of the nitrate was 321.0+/-139.3 mg (104.2-636.9 mg) in menu A, and 245.7+/-90.7 mg (140.1-507.3 mg) in menu B. Sixteen and thirteen samples exceeded the ADI in menus A and B, respectively. This may be because menu A contained more raw vegetables than menu B (menu A; 120+/-58 g, menu B; 72+/-71 g). The contents of nitrite in menu A and B were 1.2+/-0.3 mg (0.7-1.8 mg) and 2.8+/-0.9 mg (1.3-4.6 mg), respectively, and 6 samples in menu B exceeded the ADI. Intake of 350 g of vegetables or more in a day may require careful consideration of selection, frequency of use and cooking method, especially for vegetables with high nitrate content. A questionnaire to female students showed that 80% or more of students recognized that vegetables containing high contents of nitrate, such as spinach and komatsuna, should be boiled before eating them.

  10. Nitrosylation of c heme in cd(1)-nitrite reductase is enhanced during catalysis.

    Science.gov (United States)

    Rinaldo, Serena; Giardina, Giorgio; Cutruzzolà, Francesca

    2014-08-29

    The reduction of nitrite into nitric oxide (NO) in denitrifying bacteria is catalyzed by nitrite reductase. In several species, this enzyme is a heme-containing protein with one c heme and one d1 heme per monomer (cd1NiR), encoded by the nirS gene. For many years, the evidence of a link between NO and this hemeprotein represented a paradox, given that NO was known to tightly bind and, possibly, inhibit hemeproteins, including cd1NiRs. It is now established that, during catalysis, cd1NiRs diverge from "canonical" hemeproteins, since the product NO rapidly dissociates from the ferrous d1 heme, which, in turn, displays a peculiar "low" affinity for NO (KD=0.11 μM at pH 7.0). It has been also previously shown that the c heme reacts with NO at acidic pH but c heme nitrosylation was not extensively investigated, given that in cd1NiR it was considered a side reaction, rather than a genuine process controlling catalysis. The spectroscopic study of the reaction of cd1NiR and its semi-apo derivative (containing the sole c heme) with NO reported here shows that c heme nitrosylation is enhanced during catalysis; this evidence has been discussed in order to assess the potential of c heme nitrosylation as a regulatory process, as observed for cytochrome c nitrosylation in mammalian mitochondria.

  11. Nitrite addition to acidified sludge significantly improves digestibility, toxic metal removal, dewaterability and pathogen reduction

    Science.gov (United States)

    Du, Fangzhou; Keller, Jürg; Yuan, Zhiguo; Batstone, Damien J.; Freguia, Stefano; Pikaar, Ilje

    2016-12-01

    Sludge management is a major issue for water utilities globally. Poor digestibility and dewaterability are the main factors determining the cost for sludge management, whereas pathogen and toxic metal concentrations limit beneficial reuse. In this study, the effects of low level nitrite addition to acidified sludge to simultaneously enhance digestibility, toxic metal removal, dewaterability and pathogen reduction were investigated. Waste activated sludge (WAS) from a full-scale waste water treatment plant was treated at pH 2 with 10 mg NO2‑-N/L for 5 h. Biochemical methane potential tests showed an increase in the methane production of 28%, corresponding to an improvement from 247 ± 8 L CH4/kg VS to 317 ± 1 L CH4/kg VS. The enhanced removal of toxic metals further increased the methane production by another 18% to 360 ± 6 L CH4/kg VS (a total increase of 46%). The solids content of dewatered sludge increased from 14.6 ± 1.4% in the control to 18.2 ± 0.8%. A 4-log reduction for both total coliforms and E. coli was achieved. Overall, this study highlights the potential of acidification with low level nitrite addition as an effective and simple method achieving multiple improvements in terms of sludge management.

  12. Cultivation of nitrite-dependent anaerobic methane-oxidizing bacteria: impact of reactor configuration.

    Science.gov (United States)

    Hu, Baolan; He, Zhanfei; Geng, Sha; Cai, Chen; Lou, Liping; Zheng, Ping; Xu, Xinhua

    2014-09-01

    Nitrite-dependent anaerobic methane oxidation (n-damo) is mediated by bacteria that anaerobically oxidize methane coupled with nitrite reduction and is a potential bioprocess for wastewater treatment. In this work, the effect of reactor configuration on n-damo bacterial cultivation was investigated. A magnetically stirred gas lift reactor (MSGLR), a sequencing batch reactor (SBR), and a continuously stirred tank reactor (CSTR) were selected to cultivate the bacteria. Microbial community was monitored by using quantitative PCR, 16S rRNA gene sequencing, pmoA gene sequencing, and fluorescence in situ hybridization (FISH). The effects of substrate inhibition, methane mass transfer, and biomass washout in the three reactors were focused on. The results indicated that the MSGLR had the best performance among the three reactor systems, with the highest total and specific n-damo activities. Its maximum volumetric nitrogen removal rate was up to 76.9 mg N L(-1) day(-1), which was higher than previously reported values (5.1-37.8 mg N L(-1) d(-1)).

  13. Antioxidant and Nitrite-Scavenging Capacities of Phenolic Compounds from Sugarcane (Saccharum officinarum L. Tops

    Directory of Open Access Journals (Sweden)

    Jian Sun

    2014-08-01

    Full Text Available Sugarcane tops were extracted with 50% ethanol and fractionated by petroleum ether, ethyl acetate (EtOAc, and n-butyl alcohol successively. Eight phenolic compounds in EtOAc extracts were purified through silica gel and Sephadex LH-20 column chromatographies, and then identified by nuclear magnetic resonance and electrospray ionization mass spectra. The results showed that eight phenolic compounds from EtOAc extracts were identified as caffeic acid, cis-p-hydroxycinnamic acid, quercetin, apigenin, albanin A, australone A, moracin M, and 5'-geranyl-5,7,2',4'-tetrahydroxyflavone. The antioxidant and nitrite-scavenging capacities of different solvent extracts correlated positively with their total phenolic (TP contents. Amongst various extracts, EtOAc extracts possessed the highest TP content and presented the strongest oxygen radical absorbance capacity (ORAC, 1,1'-diphenyl-2-picrylhydrazyl (DPPH radical-scavenging capacity, 2,2'-azobis-3-ethylbenthiaazoline-6-sulfonic acid (ABTS radical-scavenging capacity, ferric reducing antioxidant power (FRAP and nitrite-scavenging capacity. Thus, sugarcane tops could be promoted as a source of natural antioxidant.

  14. Nitrite reductase activity of sulphate-reducing bacteria prevents their inhibition by nitrate-reducing, sulphide-oxidizing bacteria.

    Science.gov (United States)

    Greene, E A; Hubert, C; Nemati, M; Jenneman, G E; Voordouw, G

    2003-07-01

    Sulphate-reducing bacteria (SRB) can be inhibited by nitrate-reducing, sulphide-oxidizing bacteria (NR-SOB), despite the fact that these two groups are interdependent in many anaerobic environments. Practical applications of this inhibition include the reduction of sulphide concentrations in oil fields by nitrate injection. The NR-SOB Thiomicrospira sp. strain CVO was found to oxidize up to 15 mM sulphide, considerably more than three other NR-SOB strains that were tested. Sulphide oxidation increased the environmental redox potential (Eh) from -400 to +100 mV and gave 0.6 nitrite per nitrate reduced. Within the genus Desulfovibrio, strains Lac3 and Lac6 were inhibited by strain CVO and nitrate for the duration of the experiment, whereas inhibition of strains Lac15 and D. vulgaris Hildenborough was transient. The latter had very high nitrite reductase (Nrf) activity. Southern blotting with D. vulgaris nrf genes as a probe indicated the absence of homologous nrf genes from strains Lac3 and Lac6 and their presence in strain Lac15. With respect to SRB from other genera, inhibition of the known nitrite reducer Desulfobulbus propionicus by strain CVO and nitrate was transient, whereas inhibition of Desulfobacterium autotrophicum and Desulfobacter postgatei was long-lasting. The results indicate that inhibition of SRB by NR-SOB is caused by nitrite production. Nrf-containing SRB can overcome this inhibition by further reducing nitrite to ammonia, preventing a stalling of the favourable metabolic interactions between these two bacterial groups. Nrf, which is widely distributed in SRB, can thus be regarded as a resistance factor that prevents the inhibition of dissimilatory sulphate reduction by nitrite.

  15. Partial nitritation of stored source-separated urine by granular activated sludge in a sequencing batch reactor.

    Science.gov (United States)

    Chen, Liping; Yang, Xiaoxiao; Tian, Xiujun; Yao, Song; Li, Jiuyi; Wang, Aimin; Yao, Qian; Peng, Dangcong

    2017-12-01

    The combination of partial nitritation (PN) and anaerobic ammonium oxidation (anammox) has been proposed as an ideal process for nitrogen removal from source-separated urine, while the high organic matters in urine cause instability of single-stage PN-anammox process. This study aims to remove the organic matters and partially nitrify the nitrogen in urine, producing an ammonium/nitrite solution suitable for anammox. The organic matters in stored urine were used as the electron donors to achieve 40% total nitrogen removal in nitritation-denitrification process in a sequencing batch reactor (SBR). Granular aggregates were observed and high mixed liquor suspended solids (9.5 g/L) were maintained in the SBR. Around 70-75% ammonium was oxidized to nitrite under the volumetric loading rates of 3.23 kg chemical oxygen demand (COD)/(m(3) d) and 1.86 kg N/(m(3) d), respectively. The SBR produced an ammonium/nitrite solution free of biodegradable organic matters, with a NO2(-)-N:NH4(+)-N of 1.24 ± 0.13. Fluorescence in situ hybridization images showed that Nitrosomonas-like ammonium-oxidizing bacteria, accounting for 7.2% of total bacteria, located in the outer layer (25 μm), while heterotrophs distributed homogeneously throughout the granular aggregates. High concentrations of free ammonia and nitrous acids in the reactor severely inhibited the growth of nitrite-oxidizing bacteria, resulting in their absence in the granular sludge. The microbial diversity analysis indicated Proteobacteria was the predominant phylum, in which Pseudomonas was the most abundant genus.

  16. A study on the toxigenesis by Clostridium botulinum in nitrate and nitrite-reduced dry fermented sausages.

    Science.gov (United States)

    Hospital, Xavier F; Hierro, Eva; Stringer, Sandra; Fernández, Manuela

    2016-02-02

    Nitrite has been traditionally used to control Clostridium botulinum in cured meat products. However, in the case of dry fermented sausages, environmental factors such as pH, aw and the competitive microbiota may exert a more relevant role than nitrite in the inhibition of the growth and toxin production by C. botulinum. In this challenge test study, two varieties of Mediterranean dry sausages (salchichón and fuet) were inoculated with spores of C. botulinum Group I (proteolytic) and C. botulinum Group II (nonproteolytic). Sausages were prepared with 150 mg/kg of NaNO3 and 150 mg/kg of NaNO2 (maximum ingoing amounts allowed by the European Union regulation), with a 25% and 50% reduction, and without nitrate/nitrite. The initial pH in both products was 5.6, and decreased to values below 5.0 in salchichón and to 5.2 in fuet. Lactic acid bacteria counts reached 8-9 log cfu/g after fermentation. The aw decreased from initial values of 0.96 to about 0.88-0.90 at the end of ripening. Botulinum neurotoxin was not detected in any of the sausages, including those manufactured without nitrate and nitrite. Despite the environmental conditions were within the range for germination and growth of C. botulinum Group I during the first 8 days of the ripening process in fuet and 10-12 days in salchichón, acidity, aw and incubation temperature combined to inhibit the production of toxin, independently of the concentration of curing agents. Although decreasing or even removing nitrate/nitrite from the formula did not compromise safety regarding C. botulinum in the conditions tested in this study, their antimicrobial role should not be underestimated in the case that other hurdles could fail or other ripening conditions were used, and also considering the effect of nitrite on other pathogens.

  17. Hemi-ordered nanoporous carbon electrode material for highly selective determination of nitrite in physiological and environmental systems

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Shenghai; Wu, Hongmin; Wu, Ying; Shi, Hongyan; Feng, Xun; Jiang, Shang; Chen, Jian; Song, Wenbo, E-mail: wbsong@jlu.edu.cn

    2014-08-01

    Hemi-ordered nanoporous carbon (HONC) was obtained from a mesoporous silica template through a nano-replication method using furfuryl alcohol as the carbon source. The structure and morphology of HONC were characterized and analyzed in detail by X-ray diffraction, N{sub 2}-sorption, Raman spectroscopy and transmission electron microscopy. HONC was then demonstrated as active electrode material for selective determination of nitrite in either physiological or environmental system. Well separated oxidation peaks of ascorbic acid, dopamine, uric acid and nitrite were observed in physiological system, and simultaneous discrimination of catechol, hydroquinone, resorcinol and nitrite in environmental system was also accomplished. Distinctly improved performances for selective determination of nitrite (such as significantly fast and sensitive current response with especially high selectivity) coexisted with ascorbic acid, dopamine and uric acid in the physiological system, as well as with catechol, hydroquinone and resorcinol in the environmental system were achieved at HONC electrode material. The excellent discriminating ability and high selectivity for NO{sub 2}{sup −} determination were ascribed to the good electronic conductivity, unique hemi-ordered porous structure, large surface area and large number of edge plane defect sites contained on the surface of nanopore walls of HONC. Results in this work demonstrated that HONC is one of the promising catalytic electrode materials for nitrite sensor fabrication. - Highlights: • Hemi-ordered nanoporous carbon as an active electrode material • Good discriminating ability towards NO{sub 2}{sup −} from physiological or environmental system • Highly selective determination of nitrite with fast and sensitive current response.

  18. The Kinetic Aspects of the Interaction of Nitrite Ions with Sulfanilic Acid and 1-Naphthylamine in Aqueous and Micellar Media

    Science.gov (United States)

    Korneeva, O. I.; Chernova, R. K.; Doronin, S. Yu.

    2008-04-01

    The kinetics of the reaction of nitrite ions with sulfanilic acid and 1-naphthylamine in aqueous and micellar (sodium dodecyl sulfate) media was studied step-by-step. The diazotization of sulfanilic acid with the nitrite ion was found to occur virtually instantaneously. Anionic surfactant micelles did not influence the rate of this reaction. The calculated effective rate constants and activation energies of the azo coupling reaction between synthesized sulfophenyldiazonium and 1-naphthylamine showed that the passage from water into the micellar medium decelerated the reaction. It was found that sodium dodecyl sulfate micelles played the role of a reagent separator.

  19. Diversity of nitrite reductase genes (nirS) in the denitrifying water column of the coastal Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Jayakumar, D.A.; Francis, C.A.; Naqvi, S.W.A.; Ward, B.B.

    sequence. Most (58%) of the sequences fell into 3 distinct clus- ters (Clusters II, III and VIII) (Fig. 3). Clusters II, III, IV, V, XI and XII contained representatives from both Stns G8 and V4, but only from depths where nitrite was present. Cluster VII... (Braker et al. 2000), as well as mRNA clones from River Colne estuary sedi- ments (Nogales et al. 2002). Cluster XII, also supported by high bootstrap values, contained clones from Sam- ples G840, G857 and V483, all of which had high nitrite concentrations...

  20. Nitrolancea hollandica gen. nov., sp. nov., a chemolithoautotrophic nitrite-oxidizing bacterium isolated from a bioreactor belonging to the phylum Chloroflexi

    NARCIS (Netherlands)

    Sorokin, D.Y.; Vejmelkova, D.; Lücker, S.; Streshinskaya, G.M.; Rijpstra, W.I.C.; Sinninghe Damste, J.S.; Kleerbezem, R.; van Loosdrecht, M.; Muyzer, G.; Daims, H.

    2014-01-01

    A novel nitrite-oxidizing bacterium (NOB), strain LbT, was isolated from a nitrifying bioreactor with a high loading of ammonium bicarbonate in a mineral medium with nitrite as the energy source. The cells were oval (lancet-shaped) rods with pointed edges, non-motile, Gram-positive (by staining and

  1. The effect of G1c6P uptake and its subsequent oxidation within pea root plastids on nitrite reduction and glutamate synthesis

    NARCIS (Netherlands)

    Bowsher, Caroline G.; Lacey, Anne E.; Hanke, Guy T.; Clarkson, David T.; Saker, Les R.; Stulen, Ineke; Emes, Michael J.

    2007-01-01

    In roots, nitrate assimilation is dependent upon a supply of reductant that is initially generated by oxidative metabolism including the pentose phosphate pathway (OPPP). The uptake of nitrite into the plastids and its subsequent reduction by nitrite reductase (NiR) and glutamate synthase (GOGAT) ar

  2. The distal pocket histidine residue in horse heart myoglobin directs the O-binding mode of nitrite to the heme iron.

    Science.gov (United States)

    Yi, Jun; Heinecke, Julie; Tan, Hui; Ford, Peter C; Richter-Addo, George B

    2009-12-23

    It is now well-established that mammalian heme proteins are reactive with various nitrogen oxide species and that these reactions may play significant roles in mammalian physiology. For example, the ferrous heme protein myoglobin (Mb) has been shown to reduce nitrite (NO(2)(-)) to nitric oxide (NO) under hypoxic conditions. We demonstrate here that the distal pocket histidine residue (His64) of horse heart metMb(III) (i.e., ferric Mb(III)) has marked effects on the mode of nitrite ion coordination to the iron center. X-ray crystal structures were determined for the mutant proteins metMb(III) H64V (2.0 A resolution) and its nitrite ion adduct metMb(III) H64V-nitrite (1.95 A resolution), and metMb(III) H64V/V67R (1.9 A resolution) and its nitrite ion adduct metMb(III) H64V/V67R-nitrite (2.0 A resolution). These are compared to the known structures of wild-type (wt) hh metMb(III) and its nitrite ion adduct hh metMb(III)-nitrite, which binds NO(2)(-) via an O-atom in a trans-FeONO configuration. Unlike wt metMb(III), no axial H(2)O is evident in either of the metMb(III) mutant structures. In the ferric H64V-nitrite structure, replacement of the distal His residue with Val alters the binding mode of nitrite from the nitrito (O-binding) form in the wild-type protein to a weakly bound nitro (N-binding) form. Reintroducing a H-bonding residue in the H64V/V67R double mutant restores the O-binding mode of nitrite. We have also examined the effects of these mutations on reactivities of the metMb(III)s with cysteine as a reducing agent and of the (ferrous) Mb(II)s with nitrite ion under anaerobic conditions. The Mb(II)s were generated by reduction of the Mb(III) precursors in a second-order reaction with cysteine, the rate constants for this step following the order H64V/V67R > H64V > wt. The rate constants for the oxidation of the Mb(II)s by nitrite (giving NO as the other product) follow the order wt > H64V/V67R > H64V and suggest a significant role of the distal pocket H

  3. 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.

    Science.gov (United States)

    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.

  4. Nitric oxide, nitrite, and Fnr regulation of hmp (flavohemoglobin) gene expression in Escherichia coli K-12.

    Science.gov (United States)

    Poole, R K; Anjum, M F; Membrillo-Hernández, J; Kim, S O; Hughes, M N; Stewart, V

    1996-01-01

    Escherichia coli possesses a soluble flavohemoglobin, with an unknown function, encoded by the hmp gene. A monolysogen containing an hmp-lacZ operon fusion was constructed to determine how the hmp promoter is regulated in response to heme ligands (O2, NO) or the presence of anaerobically utilized electron acceptors (nitrate, nitrite). Expression of the phi (hmp-lacZ)1 fusion was similar during aerobic growth in minimal medium containing glucose, glycerol, maltose, or sorbitol as a carbon source. Mutations in cya (encoding adenylate cyclase) or changes in medium pH between 5 and 9 were without effect on aerobic expression. Levels of aerobic and anaerobic expression in glucose-containing minimal media were similar; both were unaffected by an arcA mutation. Anaerobic, but not aerobic, expression of phi (hmp-lacZ)1 was stimulated three- to four-fold by an fnr mutation; an apparent Fnr-binding site is present in the hmp promoter. Iron depletion of rich broth medium by the chelator 2'2'-dipyridyl (0.1 mM) enhanced hmp expression 40-fold under anaerobic conditions, tentatively attributed to effects on Fnr. At a higher chelator concentration (0.4 mM), hmp expression was also stimulated aerobically. Anaerobic expression was stimulated 6-fold by the presence of nitrate and 25-fold by the presence of nitrite. Induction by nitrate or nitrite was unaffected by narL and/or narP mutations, demonstrating regulation of hmp by these ions via mechanisms alternative to those implicated in the regulation of other respiratory genes. Nitric oxide (10 to 20 microM) stimulated aerobic phi (hmp-lacZ)1 activity by up to 19-fold; soxS and soxR mutations only slightly reduced the NO effect. We conclude that hmp expression is negatively regulated by Fnr under anaerobic conditions and that additional regulatory mechanisms are involved in the responses to oxygen, nitrogen compounds, and iron availability. Hmp is implicated in reactions with small nitrogen compounds. PMID:8808940

  5. Antioxidant and antimicrobial effects of condiments paste used as nitrite replacer in chicken mince

    Directory of Open Access Journals (Sweden)

    Meena Goswami

    2014-06-01

    Full Text Available Aim: The present study was conducted to evaluate the antioxidant and antimicrobial effects of 4% Ginger + 4% Garlic + Turmeric 1000ppm (GGT, nitrite 200ppm (N and the control (C on minced chicken stored at 4±10C. Materials and Methods: Physico-chemical properties (pH, Thio Barbituric acid value (TBA, Peroxide value (PV and Free Fatty acid (FFA were evaluated on 0, 3, 6 and 9th day of the storage. The antimicrobial studies viz. Total viable count (TVC, Escherichia coli count, Clostridium sporogenes count and Clostridium perfringens count were carried out on 1, 4, 7 and 10th day of storage. Results: Highly significant difference (P<0.01 was noticed between the treatments and between the storage periods in pH (5.951±0.02-GGT as compared to C-5.898±0.05and N-5.899±0.02, TBA(0.566±0.09-GGT as compared to C-1.569±0.04m and N-0.614±0.11, PV(1.679±0.18-GGT as compared to C-2.595±0.41and N-2.03±0.21, FFA(1.199±0.21-GGT as compared to C-2.284±0.40 and N-1.446±0.24 and N-7.194±0.68, TVC (log CFU/g (7.528±0.70-GGT as compared to C-8.583±0.49 and N-6.446±0.53, Escherichia coli (log CFU/g (6.476±0.54-GGT as compared to C-7.658±0.71 and N-6.609±0.61, Clostridium sporogenes count (log CFU/g (7.746±0.69-GGT as compared to C-8.681±0.74 and N- and Clostridium perfringens count (log CFU/g (6.864±0.76-GGT as compared to C-8.790±0.53 and N-6.864±0.58. Conclusion: The Ginger garlic turmeric paste has an excellent potential to replace the nitrite as a natural antioxidant with other advantages. It is highly effective against Escherichia coli. It is also significantly effective against Clostridium perfringens, Clostridium sporogenes and TVC as compared to C but lesser than N. We recommend further research by replacing the nitrite with various combinations of the spices and the condiments.

  6. Synthesis and Characterization of Coordination Compounds of Silver(I Nitrite with Ligands Ethylenethiourea and N,N'-diethylthiourea

    Directory of Open Access Journals (Sweden)

    Fariati

    2016-09-01

    Full Text Available Silver(I nitrate and ethylenethiourea (etu in 1 : 4 stochiometry have been reported [1]. Coordination compounds of A and B as silver(I nitrite with etu and silver(I nitrite with N,N’-diethylthiourea (detu respectively, have never been done. The purposes of this study are to synthesize and characterize coordination compounds of A and B. Synthesis coordination compound of A with 1 : 4, while B with 1 : 2 stoichiometry. Both of coordination compounds are conducted directly in acetonitrile. Compounds obtained are characterized by melting point, electrical conductivity measurement, SEM-EDX, qualitative nitrite test, free energy calculation and structures prediction using Spartan’14 v1.1.0. Coordination compounds of A and B are colourless needle and prism crystals; have melting point of 189°C and 103-105°C; free energy of -289,2567 and -1182.8101 kJ/mol respectively. Electrical conductivity measurement and qualitative nitrite test show that the obtained compound of A is an ionic and B is a molecular one. EDX analysis gives empirical formula prediction of two coordination compound A is C12H24AgN9O2S4 and B is C15H36AgN7O2S3.

  7. Ion chromatographic method for the simultaneous determination of nitrite and nitrate by post-column indirect fluorescence detection.

    Science.gov (United States)

    Stalikas, Constantine D; Konidari, Constantina N; Nanos, Christos G

    2003-06-20

    This short paper highlights the suitability of ion chromatography with post-column indirect fluorescence detection to determine simultaneously nitrite and nitrate based on the quenching of tryptophan native fluorescence. The method uses an enhanced fluorescence mobile phase containing tryptophan and detects the suppression of fluorescence of the mobile phase due to the elution of the target ions. The phenomenon of fluorescence quenching of tryptophan is highly induced by the presence of phosphate ions. The quenched fluorescence intensity exhibits concentration dependence in the range 1-25 mg/l and 3-65 mg/l for nitrite and nitrate, respectively. The relative standard deviation for five replicates of a standard solution containing a mixture of 5 mg/l of nitrite and 10 mg/l of nitrate lies around 2.8%. This simple coupling technique results in a relatively sensitive, fast, and accurate method, allowing for both qualitative and quantitative analysis of nitrite and nitrate. The method can easily be implemented to real samples such as foodstuffs, fertilizers and soils and is proven to be precise and accurate when compared with reference methods.

  8. Catalytic monolayer voltammetry and in situ scanning tunneling microscopy of copper nitrite reductase on cysteamine-modified Au(111) electrodes

    DEFF Research Database (Denmark)

    Zhang, Jingdong; Welinder, A.C.; Hansen, Allan Glargaard;

    2003-01-01

    on this surface could be detected. A strong cathodic catalytic wave appears in the presence of nitrite. The catalytic current follows a Michaelis-Menten pattern with a Michaelis constant of K-m approximate to 44 muM, which is close to the value for AxCuNiR in homogeneous solution. The apparent catalytic rate...

  9. Dose Response of Sodium Nitrite on Vasoactivity Associated with HBOC-201 in a Swine Model of Controlled Hemorrhage

    Science.gov (United States)

    2011-01-01

    physiology: Pig weights (25.7 :± 3.1 kg) were similar for all groups (ANOV A). Survival to 2 h was not different among groups (Fisher’s exact). Survival...29. Walker R. 1996. The metabolism of dietary nitrites and nitrates. Biochem Soc Trans. 24(3), 780-785. 30. Yu B, Volpato GP, Chang K, Bloch KD

  10. Nitrite/nitrate detection in serum based on dual-plate generator-collector currents in a microtrench.

    Science.gov (United States)

    Gross, Andrew J; Holmes, Stephanie; Dale, Sara E C; Smallwood, Miranda J; Green, Stephen J; Winlove, C Peter; Benjamin, Nigel; Winyard, Paul G; Marken, Frank

    2015-01-01

    A dual-electrode sensor is developed for rapid detection of nitrite/nitrate at micromolar levels in phosphate buffer media and in dilute horse serum without additional sample pre-treatment. A generator-collector configuration is employed so that on one electrode nitrate is reduced to nitrite and on the second electrode nitrite is oxidised back to nitrate. The resulting redox cycle gives rise to a specific and enhanced current signal which is exploited for sensitive and reliable measurement of nitrite/nitrate in the presence of oxygen. The electrode design is based on a dual-plate microtrench (approximately 15 µm inter-electrode gap) fabricated from gold-coated glass and with a nano-silver catalyst for the reduction of nitrate. Fine tuning of the phosphate buffer pH is crucial for maximising collector current signals whilst minimising unwanted gold surface oxidation. A limit of detection of 24 μM nitrate and a linear concentration range of 200-1400 μM is reported for the microtrench sensor in phosphate buffer and dilute horse serum. Relative standard deviations for repeat measurements were in the range 1.8-6.9% (n=3) indicating good repeatability in both aqueous and biological media. Preliminary method validation against the standard chemiluminescence method used in medical laboratories is reported for nitrate analysis in serum.

  11. Simultaneous determination of nitrite and nitrate in potato and water samples using negative electrospray ionization ion mobility spectrometry.

    Science.gov (United States)

    Jafari, M T; Torki, F; Saraji, M

    2012-01-01

    Nowadays, nitrite and nitrate ions are analyzed in biological samples using laborious and expensive methods; such as HPLC, CE, MS-MS. In this work, the simultaneous analysis of nitrite and nitrate ions was conducted by electrospray ionization-ion mobility spectrometry (ESI-IMS), without using any complicated or laborious derivitization step. Ion mobility spectrometry with low cost, inexpensive maintenance and very fast analysis makes an attractive technique for the simultaneous determination of these ions in foodstuff and drinking water samples. The analyte interference was systematically investigated for binary mixture analysis. The obtained results provided detection limits of 3.8 and 4.7 µg/L for nitrite and nitrate, respectively. A linear dynamic range of about 2 orders of magnitude, and relative standard deviations below 5% were obtained by the proposed method for the analysis of both ions. Also, the proposed method was used to analyze various real samples of potato and drinking water samples, and the obtained results confirmed the capability of negative ESI-IMS for the simultaneous detection of nitrite and nitrate.

  12. Fluidic automation of nitrate and nitrite bioassays in whole blood by dissolvable-film based centrifugo-pneumatic actuation

    DEFF Research Database (Denmark)

    Nwankire, Charles E.; Chan, Di-Sien S.; Gaughran, Jennifer

    2013-01-01

    This paper demonstrates the full centrifugal microfluidic integration and automation of all liquid handling steps of a 7-step fluorescence-linked immunosorbent assay (FLISA) for quantifying nitrate and nitrite levels in whole blood within about 15 min. The assay protocol encompasses the extraction...

  13. Transcriptomic analysis of Staphylococcus xylosus in the presence of nitrate and nitrite in meat reveals its response to nitrosative stress

    Directory of Open Access Journals (Sweden)

    Aurore eVermassen

    2014-12-01

    Full Text Available Staphylococcus xylosus is one of the major starter cultures used for meat fermentation because of its crucial role in the reduction of nitrate to nitrite which contributes to colour and flavour development. Despite longstanding use of these additives, their impact on the physiology of S. xylosus has not yet been explored. We present the first in situ global gene expression profile of S. xylosus in meat supplemented with nitrate and nitrite at the levels used in the meat industry. More than 600 genes of S. xylosus were differentially expressed at 24 or 72 hours of incubation. They represent more than 20% of the total genes and let us to suppose that addition of nitrate and nitrite to meat leads to a global change in gene expression. This profile revealed that S. xylosus is subject to nitrosative stress caused by reactive nitrogen species generated from nitrate and nitrite. To overcome this stress, S. xylosus has developed several oxidative stress resistance mechanisms, such as modulation of the expression of several genes involved in iron homeostasis and in antioxidant defence. Most of which belong to the Fur and PerR regulons, respectively. S. xylosus has also counteracted this stress by developing DNA and protein repair. Furthermore, it has adapted its metabolic response—carbon and nitrogen metabolism, energy production and cell wall biogenesis—to the alterations produced by nitrosative stress.

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

    Science.gov (United States)

    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.

  15. Met144Ala mutation of the copper-containing nitrite reductase from Alcaligenes xylosoxidans reverses the intramolecular electron transfer

    DEFF Research Database (Denmark)

    Farver, Ole; Eady, Robert R; Sawers, Gary

    2004-01-01

    Pulse radiolysis has been employed to investigate the intramolecular electron transfer (ET) between the type 1 (T1) and type 2 (T2) copper sites in the Met144Ala Alcaligenes xylosoxidans nitrite reductase (AxCuNiR) mutant. This mutation increases the reduction potential of the T1 copper center...

  16. Acid-induced structural modifications of unsaturated Fatty acids and phenolic olive oil constituents by nitrite ions: a chemical assessment.

    Science.gov (United States)

    Napolitano, Alessandra; Panzella, Lucia; Savarese, Maria; Sacchi, Raffaele; Giudicianni, Italo; Paolillo, Livio; d'Ischia, Marco

    2004-10-01

    The structural modifications of the unsaturated fatty acid components of triglycerides in extra virgin olive oil (EVOO) following exposure to nitrite ions in acidic media were determined by two-dimensional (2D) NMR spectroscopy, aided by (15)N labeling and GC analysis, allowing investigation of the matrix without fractionation steps. In the presence of excess nitrite ions in a 1% sulfuric acid/oil biphasic system, extensive double bond isomerization of the oleic/linoleic acid components of triglycerides was observed associated with nitration/oxidation processes. Structurally modified species were identified as E/Z-nitroalkene, 1,2-nitrohydroxy, and 3-nitro-1-alkene(1,5-diene) derivatives based on (1)H, (13)C, and (15)N 2D NMR analysis in comparison with model compounds. Minor constituents of EVOO, including phenolic compounds and tocopherols, were also substantially modified by nitrite-derived nitrating species, even under milder reaction conditions relevant to those occurring in the gastric compartments. Novel nitrated derivatives of tyrosol, hydroxytyrosol, and oleuropein (6-8) were identified by LC/MS analysis of the polar fraction of EVOO and by comparison with synthetic samples. Overall, these results provide the first systematic description at the chemical level of the consequences of exposing EVOO to nitrite ions at acidic pH and offer an improved basis for further investigations in the field of toxic nitrosation/nitration reactions and dietary antinitrosating agents.

  17. The role of nitrite and nitrate ions as photosensitizers in the phototransformation of phenolic compounds in seawater

    Energy Technology Data Exchange (ETDEWEB)

    Calza, P., E-mail: paola.calza@unito.it [Universita degli Studi di Torino, Dipartimento di Chimica, Via P. Giuria 5, 10125 Torino (Italy); Vione, D. [Universita degli Studi di Torino, Dipartimento di Chimica, Via P. Giuria 5, 10125 Torino (Italy); Universita degli Studi di Torino, Centro Interdipartimentale NatRisk, Via Leonardo da Vinci 44, 10095 Grugliasco (Italy); Novelli, A. [Max Planck Institute for Chemistry, 55128 Mainz (Germany); Pelizzetti, E.; Minero, C. [Universita degli Studi di Torino, Dipartimento di Chimica, Via P. Giuria 5, 10125 Torino (Italy)

    2012-11-15

    Nitrite and nitrate are known to be involved in photochemical processes occurring in natural waters. In this study we have investigated the role played by these photosensitizers towards the transformation of xenobiotic organic matter in marine water, with the goal of assessing the typical transformation routes induced in seawater by irradiated nitrite/nitrate. For this purpose, phenol was chosen as model molecule. Phenol transformation was investigated under simulated solar radiation in the presence of nitrite (in the range of 1 Multiplication-Sign 10{sup -5}-1 Multiplication-Sign 10{sup -2} M) or nitrate ions, in pure water at pH 8, in artificial seawater (containing same dissolved salts as seawater but no organic matter), and in natural seawater. In all experiments, phenol degradation rate and formation of intermediates were assessed. As expected, phenol disappearance rate decreased with decreasing nitrite concentration and was slightly reduced by the presence of chloride. Other salts present in artificial seawater (e.g. HCO{sub 3}{sup -}, CO{sub 3}{sup 2-} and Br{sup -}) had a more marked effect on phenol transformation. Analysis of intermediates formed in the different matrices under study showed generation of hydroxyl-, nitro- and chloroderivatives of phenol, to a different extent depending on experimental conditions. 1,4-Benzoquinone prevailed in all cases, nitroderivatives were only formed with nitrite but were not detected in nitrate-spiked solutions. Competition was observed between halogenation and nitration of phenol, with variable outcome depending on nitrite concentration. The most likely reason is competition between nitrating and halogenating species for reaction with the phenoxyl radical. A kinetic model able to justify the occurrence of different intermediates under the adopted conditions is presented and discussed. -- Highlights: Black-Right-Pointing-Pointer Nitrite and nitrate-mediated solar-driven transformations of pollutant in seawater were

  18. Stability of the Caustic-Side Solvent Extraction (CSSX) Process Solvent: Effect of High Nitrite on Solvent Nitration

    Energy Technology Data Exchange (ETDEWEB)

    Bonnesen, P.V.

    2002-06-26

    The purpose of this investigation was to determine whether nitrated organic compounds could be formed during operation of the Caustic-Side Solvent Extraction (CSSX) process, and whether such compounds would present a safety concern. The CSSX process was developed to remove cesium from alkaline high-level salt waste stored at the US Department of Energy Savannah River Site (SRS). The solvent is composed of the cesium extractant calix[4]arene-bis-(4-tert-octylbenzo-crown-6) (BOBCalixC6), a fluorinated alcohol phase modifier, tri-n-octylamine (TOA), and an isoparaffinic diluent (Iospar{reg_sign}). During the CSSX process, the solvent is expected to be exposed to high concentrations of nitrate and nitrite dissolved in the alkaline waste feed. The solvent will also be exposed to dilute (50 mM) nitric acid solutions containing low concentrations of nitrite during scrubbing, followed by stripping with 1 mM nitric acid. The solvent is expected to last for one year of plant operation, and the temperatures the solvent may experience during the process could range from as low as 15 C to as high as 35 C. Excursions from standard process conditions could result in the solvent experiencing higher temperatures, as well as concentrations of nitrate, nitrite, and most importantly nitric acid, that exceed normal operating conditions. Accordingly, conditions may exist where nitration reactions involving the solvent components, possibly leading to other chemical reactions stemming from nitration reactions, could occur. To model such nitration reactions, the solvent was exposed to the types of nitrate- and nitrite-containing solutions that might be expected to be encountered during the process (even under off-normal conditions), as a function of time, temperature, and concentration of nitrate, nitrite, and nitric acid. The experiments conducted as part of this report were designed to examine the more specific effect that high nitrite concentrations could have on forming nitrated

  19. Biodegradation of tetramethylammonium hydroxide (TMAH) in completely autotrophic nitrogen removal over nitrite (CANON) process.

    Science.gov (United States)

    Chen, Shen-Yi; Lu, Li-An; Lin, Jih-Gaw

    2016-06-01

    This study conducted a completely autotrophic nitrogen removal over nitrite (CANON) process in a continuous anoxic upflow bioreactor to treat synthetic wastewater with TMAH (tetramethylammonium hydroxide) ranging from 200 to 1000mg/L. The intermediates were analyzed for understanding the metabolic pathway of TMAH biodegradation in CANON process. In addition, (15)N-labeled TMAH was used as the substrate in a batch anoxic bioreactor to confirm that TMAH was converted to nitrogen gas in CANON process. The results indicated that TMAH was almost completely biodegraded in CANON system at different influent TMAH concentrations of 200, 500, and 1000mg/L. The average removal efficiencies of total nitrogen were higher than 90% during the experiments. Trimethylamine (TMA) and methylamine (MA) were found to be the main biodegradation intermediates of TMAH in CANON process. The production of nitrogen gas with (15)N-labeled during the batch anaerobic bioreactor indicated that CANON process successfully converted TMAH into nitrogen gas.

  20. Hubungan antara Indeks Massa Tubuh dengan Kadar Nitrit Oksid pada Masyarakat Etnik Minangkabau di Kota Padang

    Directory of Open Access Journals (Sweden)

    Nidia Purwadianti

    2015-05-01

    Full Text Available AbstrakObesitas merupakan masalah kesehatan yang kompleks dengan penyebab multifaktorial. Obesitas berkaitan erat dengan peningkatan risiko sejumlah komplikasi seperti hipertensi. Salah satu mekanisme yang menghubungkan obesitas dengan hipertensi adalah disfungsi endotel sebagai akibat penurunan kadar nitrit oksid (NO. Pengukuran Indeks Massa Tubuh (IMT merupakan salah satu indikator untuk menentukan obesitas. .Tujuan penelitian ini ialah menentukan hubungan IMT dengan kadar nitrit oksid pada masyarakat etnik Minangkabau. Desain penelitian adalah studi potong lintang dengan populasi masyarakat etnik Minangkabau usia 30 – 65 tahun di 4 kecamatan terpilih di Kota Padang. Jumlah subjek sebanyak 130 orang. Data responden merupakan data sekunder yang dianalisis menggunakan uji korelasi Pearson dan uji beda rerata dengan metode independent sample t-test. Hasil penelitian pada kelompok obesitas diperoleh p-value = 0,982 dengan r = -0,003. Pada kelompok tidak obesitas didapatkan p-value = 0,924 dan r = -0,013. Berdasarkan hasil tersebut dapat disimpulkan bahwa tidak terdapat hubungan yang bermakna antara IMT dengan kadar NO. Kadar nitrit oksid rerata pada responden obesitas adalah 28,37±17,45 μmol/L dan tidak obesitas adalah 23,91±11,55 μmol/L dengan p-value=0,084. Terdapat perbedaan rerata kadar NO kelompok obesitas dan tidak obesitas pada masyarakat etnik Minangkabau di Kota Padang namun tidak bermakna secara statistik. Diharapkan penelitian lebih lanjut dengan mempertimbangkan faktor lain yang mempengaruhi kadar NO selain IMT.Kata kunci: indeks massa tubuh, kadar nitrit oksid, obesitas AbstractObesity is a complex health problem with multifactorial causes. Obesity is strongly related to risk increase of many complications such as hypertension. One of the mechanisms that links obesity and hypertension is endhotelial disfunction due to nitric oxide (NO level decrease. Body Mass Index (BMI measurement is one of the indicators to determine obesity

  1. Rapid Microwave-Assisted Copper-Catalyzed Nitration of Aromatic Halides with Nitrite Salts

    Energy Technology Data Exchange (ETDEWEB)

    Paik, Seung Uk; Jung, Myoung Geun [Keimyung University, Daegu (Korea, Republic of)

    2012-02-15

    A rapid and efficient copper-catalyzed nitration of aryl halides has been established under microwave irradiation. The catalytic systems were found to be the most effective with 4-substituted aryl iodides leading to nearly complete conversions. Nitration of aromatic compounds is one of the important industrial processes as underlying intermediates in the manufacture of a wide range of chemicals such as dyes, pharmaceuticals, agrochemicals and explosives. General methods for the nitration of aromatic compounds utilize strongly acidic conditions employing nitric acid or a mixture of nitric and sulfuric acids, sometimes leading to problems with poor regioselectivity, overnitration, oxidized byproducts and excess acid waste in many cases of functionalized aromatic compounds. Several other nitrating agents or methods avoiding harsh reaction conditions have been explored using metal nitrates, nitrite salts, and ionic liquid-mediated or microwave-assisted nitrations. Recently, copper or palladium compounds have been successfully used as efficient catalysts for the arylation of amines with aryl halides under mild conditions.

  2. Nitrification-denitrification via nitrite pathway in biological treatment of hypersaline wastewater

    Institute of Scientific and Technical Information of China (English)

    ZHU Gui-Bing; PENG Yong-Zhen; MENG Xiang-Sheng; YU De-shuang

    2008-01-01

    Pilot-scale studies on biological treatment of hypersaline wastewater at low temperature were conduc-ted and results showed that seawater salinity had a strong negative effect on notronomonas and nitrobacter growth, but much more on the nitrobacter. The nitrification action was mainly accomplished by nitrosomonas. Bench-scale experiments using two SBRs were carried out for further investigation under different conditions of salinities, ammonia loadings and temperatures. Biological nitrogen removal via nitrite pathway from wastewater containing 30 percent seawater was achieved, but the ammonia removal efficiency was strongly related not only to the influent ammonia loading at different salinities but also to temperatures. When the ratio of seawater to wastewater was 30 percent, and the ammonia loading was below the critical value of 0. 15 kgNH4+-N/( kgMLSS and 20℃ when the influent ammonia concentration was 60-80 mg/L and pH was 7.5-8.0.

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

    DEFF Research Database (Denmark)

    Vlaeminck, S.E.; Terada, Akihiko; Smets, Barth F.

    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......AOB-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....

  4. Determination of hydroxyl radicals with salicylic acid in aqueous nitrate and nitrite solutions

    Institute of Scientific and Technical Information of China (English)

    YANG Xi; ZHAN Man-jun; KONG Ling-ren; WANG Lian-sheng

    2004-01-01

    The qualitative and quantitative analyses of reactive oxygen species are essential to determine their steady-state concentration and related reaction mechanisms in environmental aquatic systems. In this study, salicylic acid was employed as an innovative molecular probe of hydroxyl radical(OH) generated in aqueous nitrate and nitrite solutions through photochemical reactions. Kinetic studies showed that the steady-state concentrations of OH in aqueous NO3-(10 mmol/L, pH = 5) and NO2- (10 mmol/L, pH = 5) solutions under ultraviolet irradiation were at a same magnitude, 10-15 mol/L. Apparent quantum yields of OH at 313 nm were measured as 0.011 and 0.07 for NO3- and NO2- respectively, all comparable to the results of previous studies.

  5. Manganese dioxide graphite composite electrodes: application to the electroanalysis of hydrogen peroxide, ascorbic acid and nitrite.

    Science.gov (United States)

    Langley, Cathryn E; Sljukić, Biljana; Banks, Craig E; Compton, Richard G

    2007-02-01

    The modification of carbon powder with manganese dioxide using a wet impregnation procedure with electrochemical characterisation of the modified powder is described. The process involves saturation of the carbon powder with manganese(II) nitrate followed by thermal treatment at ca. 773 K leading to formation of manganese(IV) oxide on the surface of the carbon powder. The construction of composite electrodes based on manganese dioxide modified carbon powder and epoxy resin is also described, including optimisation of the percentage of the modified carbon powder. Composite electrodes showed attractive performances for electroanalytical applications, proving to be suitable for the electrochemical detection of hydrogen peroxide, ascorbic acid and nitrite ions with limits of detection comparable to the detection limits achieved by other analytical techniques. The results obtained for detection of these analytes, together with composite electrodes flexible design and low cost offers potential application of composite electrodes in biosensors.

  6. Sensitivity analysis of a biofilm model describing mixed growth of nitrite oxidisers in a CSTR.

    Science.gov (United States)

    Kornaros, M; Dokianakis, S N; Lyberatos, G

    2006-01-01

    A simple kinetic model has been developed for describing nitrite oxidation by autotrophic aerobic nitrifiers in a CSTR reactor, in which mixed (suspended and attached) growth conditions are prevailing. In this work, a critical dimensionless parameter is identified containing both biofilm characteristics and microbial kinetic parameters, as well as the specific (per volume) surface of the reactor configuration used. Evaluation of this dimensionless parameter can easily provide information on whether or not wall attachment is critical, and should be taken into account either in kinetic studies or in reactor design, when specific pollutants are to be removed from the waste influent stream. The effect of bulk dissolved oxygen (DO) concentration on the validity of this model is addressed and minimum non-limiting DO concentrations are proposed depending on the reactor configuration.

  7. Effect of Nitrite Ions on Steel Corrosion Induced by Chloride or Sulfate Ions

    Directory of Open Access Journals (Sweden)

    Zhonglu Cao

    2013-01-01

    Full Text Available The influence of nitrite concentration on the corrosion of steel immersed in three simulated pH environments containing chloride ions or sulfate ions has been investigated by comparing and analyzing the change of half-cell potential, the change of threshold level of Cl- or SO42-, the change of threshold level of NO2-/Cl- or NO2-/SO42- mole ratio, and the changes of anodic/cathodic polarization curves and Stern-Geary constant B. The corrosivity of chloride ions against sulfate ions also has been discussed in pH 12.6, pH 10.3, and pH 8.1 environments containing 0, 0.053, and 0.2 mol/L NO2, respectively.

  8. Use of lysozyme from chicken egg white as a nitrite replacer in an Italian-type chicken sausage

    Directory of Open Access Journals (Sweden)

    Nalaka Sandun Abeyrathne

    2015-09-01

    Full Text Available Background: Sodium or potassium nitrite is widely used as a curing agent in sausages and other cured meat products. Nitrite has strong antimicrobial and antioxidant effects and generates cured meat color. Nitrite, however, can react with secondary or tertiary amines in meat to form carcinogenic, teratogenic and mutagenic N-nitroso compounds. Several findings have been suggested that high consumption of processed meat may increase the risk of cancer, and emphasized that dietary nitrosamines are positively associated with cancer. Lysozyme is one of the major egg proteins that have antimicrobial and antioxidant characteristics. Therefore, lysozyme can be used in meat processing to prevent microbial growth and oxidative degradation in meat products during storage. This study is focused on evaluating the antimicrobial and antioxidant effects of lysozyme extracted from egg white as a replacer of nitrite in a cooked Italian-type chicken sausage. Methods: Four curing treatments including 100% nitrite (control, 100% lysozyme (treatment 1, 25% nitrite + 75% lysozyme (treatment 2 and 50% nitrite + 50% lysozyme (treatment 3 were used to prepare Italian-type chicken sausage samples. Recipe was developed with 64% (w/w meat, 17% (w/w binder (bread crumble, 12% (w/w ice, 4% (w/w vegetable oil, 2% (w/w salt, 1% (w/w spices (chili, black pepper, cardamom. Prepared samples were cooked in an 80 °C smoke house to a core temperature of 65 °C and cooled in cold water to 20-25 °C subsequently packed in polyethylene and stored in a freezer (-18 °C. The antimicrobial effect lysozyme was tested using Escherichia coli and Salmonella. The growth of these pathogens at 0, 3 and 5 days of storage of spore inoculation was determined. The antioxidant activity of lysozyme was determined using the TBARS value during the 25 d storage period. The redness (a*, lightness (L*, and yellowness (b* of sausages were analyzed using a Minolta color meter (CR 410, Konica Minolta Inc

  9. Use of acid whey and mustard seed to replace nitrites during cooked sausage production.

    Science.gov (United States)

    Wójciak, Karolina M; Karwowska, Małgorzata; Dolatowski, Zbigniew J

    2014-02-01

    The aim was to determine the effects of sea salt, acid whey, native and autoclaved mustard seed on the physico-chemical properties, especially colour formation, microbial stability and sensory evaluation of non-nitrite cooked sausage during chilling storage. The cooked pork sausages were divided into 4 groups (group I--control sausages with curing salt (2.8%) and water (5%) added; group II--sausages with sea salt (2.8%) and acid whey (5%) added; group III--sausages with sea salt (2.8%), acid whey (5%) and mustard seed (1%) added; group IV--sausages with sea salt (2.8%), acid whey (5%) and autoclaved mustard seed (1%) added). Instrumental colour (L*, a*, b*), oxygenation index (ΔR), 650/570 nm ratio, heme iron, pH value and water activity (aw) were determined 1 day after production and after 10, 20 and 30 days of refrigerated storage (4 °C). Sensory analysis was conducted immediately after production (day 1). Microbial analysis (lactic acid bacteria, total viable count, Clostridium spp.) was determinated at the end of storage (30 days). The autoclaved mustard with acid whey can be used at 1.0% (w/w) of model cooked sausages with beneficial effect on physico-chemical and sensory qualities of no-nitrite sausage. This product can be stored at refrigeration temperature for up to 30 days, in vacuum, with good acceptability. The colour, visual appearance and overall quality of samples with autoclaved mustard seed and acid whey were similar to the control with curing agent.

  10. Facile synthesis of flower like copper oxide and their application to hydrogen peroxide and nitrite sensing

    Directory of Open Access Journals (Sweden)

    Zhang Li

    2011-12-01

    Full Text Available Abstract Background The detection of hydrogen peroxide (H2O2 and nitrite ion (NO2- is of great important in various fields including clinic, food, pharmaceutical and environmental analyses. Compared with many methods that have been developed for the determination of them, the electrochemical detection method has attracted much attention. In recent years, with the development of nanotechnology, many kinds of micro/nano-scale materials have been used in the construction of electrochemical biosensors because of their unique and particular properties. Among these catalysts, copper oxide (CuO, as a well known p-type semiconductor, has gained increasing attention not only for its unique properties but also for its applications in many fields such as gas sensors, photocatalyst and electrochemistry sensors. Continuing our previous investigations on transition-metal oxide including cuprous oxide and α-Fe2O3 modified electrode, in the present paper we examine the electrochemical and electrocatalytical behavior of flower like copper oxide modified glass carbon electrodes (CuO/GCE. Results Flower like copper oxide (CuO composed of many nanoflake was synthesized by a simple hydrothermal reaction and characterized using field-emission scanning electron microscopy (FE-SEM and X-ray diffraction (XRD. CuO modified glass carbon electrode (CuO/GCE was fabricated and characterized electrochemically. A highly sensitive method for the rapid amperometric detection of hydrogen peroxide (H2O2 and nitrite (NO2- was reported. Conclusions Due to the large specific surface area and inner characteristic of the flower like CuO, the resulting electrode show excellent electrocatalytic reduction for H2O2 and oxidation of NO2-. Its sensitivity, low detection limit, fast response time and simplicity are satisfactory. Furthermore, this synthetic approach can also be applied for the synthesis of other inorganic oxides with improved performances and they can also be extended to

  11. Anticoagulants and other preanalytical factors interfere in plasma nitrate/nitrite quantification by the Griess method.

    Science.gov (United States)

    Ricart-Jané, D; Llobera, M; López-Tejero, M D

    2002-03-01

    Nitric oxide (NO) is a signal molecule with functions such as neurotransmission, local vascular relaxation, and anti-inflammation in many physiological and pathological processes. Various factors regulate its intracellular lifetime. Due to its high reactivity in biological systems, it is transformed in the bloodstream into nitrates (NO(-)(3)) by oxyhemoglobin. The Griess reaction is a technically simple method (spectrophotometric, 540 nm) for the analysis of nitrites (NO(-)(2)) in aqueous solutions. We studied the interference of common anticoagulants in the quantification of nitrate and nitrite in plasma samples by the Griess method. We obtained rat plasma using heparin or sodium EDTA as anticoagulants, then added, or otherwise, known NO(-)(3) amounts in order to calculate their recovery. We also studied the effect of ultra-filtration performed before Griess reaction on plasma and aqueous solutions of various anticoagulants (heparin, EDTA, and also sodium citrate) to compare the recoveries of added NO(-)(3) or NO(-)(2). We used standards of NO(-)(3) or NO(-)(2) for quantification. We conclude that: (i) The bacterial nitrate reductase used to reduce NO(-)(3) to NO(-)(2) is unstable in certain storage conditions and interferes with different volumes of plasma used. (ii) The ultrafiltration (which is sometimes performed before the Griess reaction) of plasma obtained with EDTA or citrate is not recommended because it leads to overestimation of NO(minus sign)(3). In contrast, ultrafiltration is necessary when heparin is used. (iii) The absorbance at 540 nm attributed to plasma itself (basal value or background) interferes in final quantification, especially when ultrafiltration is not performed. For the quantification of plasma NO(-)(3) we recommend: sodium EDTA as anticoagulant, no ultrafiltration of plasma, and measurement of the absorbance background of each sample.

  12. [Performance and substrate inhibition kinetics model of nitritation process in inverse turbulent bed reactor].

    Science.gov (United States)

    Jin, Ren-Cun; Yang, Guang-Feng; Ma, Chun; Zheng, Ping

    2011-01-01

    The performance of a nitritation inverse turbulent bed (ITB) reactor was tested and the substrate inhibition kinetics characteristics of the reactor were analyzed. The results showed that a rapid reactor startup could be realized within 20 d with a strategy that combined the biofilm attachment method named "precoating carrier treatment" and "rapid suspending sludge discharge", with the feeding strategy named "low strength, high load". When operated at a hydraulic retention time of 3 h and influent NH4(+) -N of 700 mg x L(-1), corresponding to a nitrogen loading rate of 5.60 kg x (m3 x d)(-1), a maximum NH4(+) -N removal rate of 4.25 kg x (m3 x d)(-1) was observed. The maximum NO2(-) -N production rate was as high as 3.70 kg x (m3 x d)(-1). Four inhibition kinetic models (Haldane, Edwards, Aiba and Luong) were analyzed through non-linear regression to represent the inhibitions caused by substrate of nitritation process and the parameters of models were gained, which were r(max) of 1.84 kg x (m3 x d)(-1), K(IH) of 97.4 mg x L(-1) and K(m) of 0.188 mg x L(-1) for Haldane model, and r(max) of 1.83 kg x (m3 x d)(-1) and K(IA) of 114 mg x L(-1) for Aiba model. It was proposed that Haldane and Aiba models well fitted the process data harvested in the ITB reactor.

  13. Toxicity detection of sodium nitrite, borax and aluminum potassium sulfate using electrochemical method

    Institute of Scientific and Technical Information of China (English)

    Dengbin Yu; Daming Yong; Shaojun Dong

    2013-01-01

    Based on the inhibition effect on the respiratory chain activity of microorganisms by toxicants,an electrochemical method has been developed to measure the current variation of a mediator in the presence of microorganisms contacted with a toxicant.Microelectrode arrays were adopted in this study,which can accelerate the mass transfer rate of an analyte to the electrode and also increase the total current signal,resulting in an improvement in detection sensitivity.We selected Escherichia coli as the testee and the standard glucoseglutamic acid as an exogenous material.Under oxygen restriction,the experiments in the presence of toxicant were performed at optimum conditions (solution pH 7.0,37℃ and reaction for 3 hr).The resulting solution was then separated from the suspended microorganisms and was measured by an electrochemical method,using ferricyanide as a mediator.The current signal obtained represents the re oxidation of ferrocyanide,which was transformed to inhibiting efficiency,IC50,as a quantitative measure of toxicity.The IC50 values measured were 410,570 and 830 mg/L for sodium nitrite,borax and aluminum potassium sulfate,respectively.The results show that the toxicity sequence for these three food additives is consistent with the value reported by other methods.Furthermore,the order of damage degree to the microorganism was also observed to be:sodium nitrite > borax > aluminum potassium sulfate >blank,according to the atomic force microscopy images of E.coli after being incubated for 3 hr with the toxic compound in buffer solutions.The electrochemical method is expected to be a sensitive and simple alternative to toxicity screening for chemical food additives.

  14. Hydrogenase activity in Azospirillum brasilense is inhibited by nitrite, nitric oxide, carbon monoxide, and acetylene

    Energy Technology Data Exchange (ETDEWEB)

    Tibelius, K.H.; Knowles, R.

    1984-10-01

    Nitrite, NO, CO, and C/sub 2/H/sub 2/ inhibited O/sub 2/-dependent H/sub 2/ uptake (H/sup 3/H oxidation) in denitrifying Azospirillum brasilense Sp7 grown anaerobically on N/sub 2/O or NO/sub 3//sup -/. The apparent K/sub i/ values for inhibition of O/sub 2/-dependent H/sub 2/ uptake were 20 ..mu..M for NO/sub 2//sup -/, 0.4 ..mu..M for NO, 28 ..mu..M for CO, and 88 ..mu..M for C/sub 2/H/sub 2/. These inhibitors also affected methylene blue-dependent H/sub 2/ uptake, presumably by acting directly on the hydrogenase. Nitrite and NO inhibited H/sub 2/ uptake irreversibly, whereas inhibition due to CO was easily reversed by repeatedly evacuating and backfilling with N/sub 2/. The C/sub 2/H/sub 2/ inhibition was not readily reversed, partly due to difficulty in removing the last traces of this gas from solution. The NO/sub 2//sup -/ inhibition of malate-dependent respiration was readily reversed by repeatedly washing the cells, in contrast to the effect of NO/sub 2//sup -/ on H/sub 2/-dependent respiration. These results suggest that the low hydrogenase activities observed in NO/sub 3//sup -/-grown cultures of A. brasilense may be due to the irreversible inhibition of hydrogenase by NO/sub 2//sup -/ and NO produced by NO/sub 3//sup -/ reduction.

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

    Science.gov (United States)

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

    2017-04-15

    Nitrite (NO2(-)) 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 NO2(-) 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 NO2(-) 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.

  16. A fast and sensitive method for the determination of nitrite in human plasma by capillary electrophoresis with fluorescence detection.

    Science.gov (United States)

    Wang, Xu; Adams, Erwin; Van Schepdael, Ann

    2012-08-15

    Analysis of nitrite, the indicator of nitric oxide (NO) generation in vivo, provides a useful tool to study NO synthesis in vivo. A fast and sensitive fluorometric CE method was developed for determination of nitrite in human plasma through its derivatization with 2,3-diaminonaphthalene (DAN). Nitrite in human plasma was easily reacted with DAN under acid conditions to yield the highly fluorescent 2,3-naphthotriazole (NAT). Fluorescence detection was optimized to achieve subnanomolar detection which allows a direct analysis of plasma samples unlike most CE-UV methods using sample stacking. Acetonitrile was used to remove the protein. Short-end injection and a high voltage (-30 kV) were used to shorten the analysis time. The good separation was achieved with 20 mM borate buffer at pH 9.23. The separation of NAT was obtained within 1.4 min. The deproteinized plasma sample was injected hydrodynamically for 5s at -50 mbar into a 60 cm × 75 μm internal diameter uncoated fused-silica capillary. Excitation wavelength was selected with a broad-band filter (240-400 nm), and the emitted light was measured at 418 nm by the use of a cutoff filter. A good linearity (R(2)=0.9975) was obtained in the range from 2 to 500 nM. The detection limit of nitrite was 0.6 nM in original plasma samples, which is 750 times lower than our previous CE-UV method. The developed fluorometric CE method offers the advantages of more simple system and lower cost compared with the current fluorometric HPLC methods without losing sensitivity. The detected mean nitrite concentration in human plasma by this method was consistent with the most frequently reported values.

  17. Achieving complete nitrogen removal by coupling nitritation-anammox and methane-dependent denitrification: A model-based study.

    Science.gov (United States)

    Chen, Xueming; Guo, Jianhua; Xie, Guo-Jun; Yuan, Zhiguo; Ni, Bing-Jie

    2016-05-01

    The discovery of denitrifying anaerobic methane oxidation (DAMO) processes enables the complete nitrogen removal from wastewater by utilizing the methane produced on site from anaerobic digesters. This model-based study investigated the mechanisms and operational window for efficient nitrogen removal by coupling nitritation-anaerobic ammonium oxidation (Anammox) and methane-dependent denitrification in membrane biofilm reactors (MBfRs). A mathematical model was applied to describe the microbial interactions among Anammox bacteria, DAMO archaea, and DAMO bacteria. The model sufficiently described the batch experimental data from an MBfR containing an Anammox-DAMO biofilm with different feeding nitrogen compositions, which confirmed the validity of the model. The effects of process parameters on the system performance and microbial community structure could therefore be reliably evaluated. The impacts of nitritation produced NO2(-)/NH4(+) ratio, methane supply, biofilm thickness and total nitrogen (TN) surface loading were comprehensively investigated with the model. Results showed that the optimum NO2(-)/NH4(+) ratio produced from nitritation for the Anammox-DAMO biofilm system was around 1.0 in order to achieve the maximum TN removal (over 99.0%), independent on TN surface loading. The corresponding optimal methane supply increased while the associated methane utilization efficiency decreased with the increase of TN surface loading. The cooperation between DAMO organisms and Anammox bacteria played the key role in the TN removal. Based on these results, the proof-of-concept feasibility of a single-stage MBfR coupling nitritation-Anammox-DAMO for complete nitrogen removal was also tested through integrating the model with ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) processes whilst controlling the dissolved oxygen (DO) concentration in the simulated system. The maximum TN removal was found to be achieved at the bulk DO concentration of

  18. Structures, internal rotor potentials, and thermochemical properties for a series of nitrocarbonyls, nitroolefins, corresponding nitrites, and their carbon centered radicals.

    Science.gov (United States)

    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).

  19. Acute hemodynamic effects of inhaled sodium nitrite in pulmonary hypertension associated with heart failure with preserved ejection fraction

    Science.gov (United States)

    Simon, Marc A.; Vanderpool, Rebecca R.; Nouraie, Mehdi; Bachman, Timothy N.; White, Pamela M.; Sugahara, Masataka; Gorcsan, John; Parsley, Ed L.; Gladwin, Mark T.

    2016-01-01

    BACKGROUND. Pulmonary hypertension (PH) is associated with poor outcomes, yet specific treatments only exist for a small subset of patients. The most common form of PH is that associated with left heart disease (Group 2), for which there is no approved therapy. Nitrite has shown efficacy in preclinical animal models of Group 1 and 2 PH, as well as in patients with left heart failure with preserved ejection fraction (HFpEF). We evaluated the safety and efficacy of a potentially novel inhaled formulation of nitrite in PH-HFpEF patients as compared with Group 1 and 3 PH. METHODS. Cardiopulmonary hemodynamics were recorded after acute administration of inhaled nitrite at 2 doses, 45 and 90 mg. Safety endpoints included change in systemic blood pressure and methemoglobin levels. Responses were also compared with those administered inhaled nitric oxide. RESULTS. Thirty-six patients were enrolled (10 PH-HFpEF, 20 Group 1 pulmonary arterial hypertension patients on background PH-specific therapy, and 6 Group 3 PH). Drug administration was well tolerated. Nitrite inhalation significantly lowered pulmonary, right atrial, and pulmonary capillary wedge pressures, most pronounced in patients with PH-HFpEF. There was a modest decrease in cardiac output and systemic blood pressure. Pulmonary vascular resistance decreased only in Group 3 PH patients. There was substantial increase in pulmonary artery compliance, most pronounced in patients with PH-HFpEF. CONCLUSIONS. Inhaled nitrite is safe in PH patients and may be efficacious in PH-HFpEF and Group 3 PH primarily via improvements in left and right ventricular filling pressures and pulmonary artery compliance. The lack of change in pulmonary vascular resistance likely may limit efficacy for Group 1 patients. TRIAL REGISTRATION. ClinicalTrials.gov NCT01431313 FUNDING. This work was supported in part by the NIH grants P01HL103455 (to MAS and MTG), R01HL098032 (to MTG), and R01HL096973 (to MTG), and Mast Therapeutics, Inc. PMID

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

    Institute of Scientific and Technical Information of China (English)

    ZHANG Dan; ZHANG De-min; LIU Yao-ping; CAO Wen-wei; CHEN Guan-xiong

    2004-01-01

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

  1. Use of Griess reagent containing vanadium(III) for post-column derivatization and simultaneous determination of nitrite and nitrate in baby food.

    Science.gov (United States)

    Casanova, John A; Gross, Lois K; McMullen, Sarah E; Schenck, Frank J

    2006-01-01

    An ion chromatographic method with post-column derivatization and spectrophotometric detection is presented for the determination of nitrate and nitrite (NOx) in baby food. NOx residues found naturally or added as preservatives were extracted from baby foods and determined by using ion chromatography with post-column derivatization and spectrophotometric detection. Nitrate was reduced to nitrite online by post-column reduction using vanadium(lll) chloride and heat. Nitrite reacted with Griess reagent to produce a dye that was detected at 525 nm. The use of V(III) and heat to promote the reduction of nitrate to nitrite online is a novel feature of this detection system. The determination of incurred NOx residues in samples by using AOAC Method 993.03 yielded results comparable to those obtained by ion chromatography with spectrophotometric detection. The toxic and carcinogenic metal cadmium used in the AOAC Method to reduce the nitrate to nitrite was avoided. The proposed method provides simultaneous determination of nitrate and nitrite. Average recoveries of nitrate and nitrite residues ranged from 82 to 107% for fortification levels of 25-400 ppm.

  2. 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.

    Science.gov (United States)

    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

  3. Eliminació biològica de nitrogen via nitrit d'un corrent amb alta càrrega d'amoni Nitrite pathway biological nitrogen removal of a high strength ammonium wastewater /

    OpenAIRE

    Torà Suárez, Josep A.

    2012-01-01

    Descripció del recurs: el 01 setembre 2012 En aquesta tesi s'ha estudiat l'eliminació biològica de nitrogen en aigües residuals amb alta càrrega d'amoni. Aplicant certes condicions d'operació en un sistema de llots actius es pot aconseguir la nitrificació parcial o nitritació, que és l'oxidació de l'amoni a nitrit, evitant la conseqüent oxidació d'aquest nitrit a nitrat. Aquesta reducció en el procés de nitrificació aporta un seguit d'avantatges en front de la nitrificació convencional, ta...

  4. Mainstream partial nitritation and anammox: long-term process stability and effluent quality at low temperatures.

    Science.gov (United States)

    Laureni, Michele; Falås, Per; Robin, Orlane; Wick, Arne; Weissbrodt, David G; Nielsen, Jeppe Lund; Ternes, Thomas A; Morgenroth, Eberhard; Joss, Adriano

    2016-09-15

    The implementation of autotrophic anaerobic ammonium oxidation processes for the removal of nitrogen from municipal wastewater (known as "mainstream anammox") bears the potential to bring wastewater treatment plants close to energy autarky. The aim of the present work was to assess the long-term stability of partial nitritation/anammox (PN/A) processes operating at low temperatures and their reliability in meeting nitrogen concentrations in the range of typical discharge limits below 2  [Formula: see text] and 10 mgNtot·L(-1). Two main 12-L sequencing batch reactors were operated in parallel for PN/A on aerobically pre-treated municipal wastewater (21 ± 5 [Formula: see text] and residual 69 ± 19 mgCODtot·L(-1)) for more than one year, including over 5 months at 15 °C. The two systems consisted of a moving bed biofilm reactor (MBBR) and a hybrid MBBR (H-MBBR) with flocculent biomass. Operation at limiting oxygen concentrations (0.15-0.18 [Formula: see text] ) allowed stable suppression of the activity of nitrite-oxidizing bacteria at 15 °C with a production of nitrate over ammonium consumed as low as 16% in the MBBR. Promising nitrogen removal rates of 20-40 mgN·L(-1)·d(-1) were maintained at hydraulic retention times of 14 h. Stable ammonium and total nitrogen removal efficiencies over 90% and 70% respectively were achieved. Both reactors reached average concentrations of total nitrogen below 10 mgN·L(-1) in their effluents, even down to 6 mgN·L(-1) for the MBBR, with an ammonium concentration of 2 mgN·L(-1) (set as operational threshold to stop aeration). Furthermore, the two PN/A systems performed almost identically with respect to the biological removal of organic micropollutants and, importantly, to a similar extent as conventional treatments. A sudden temperature drop to 11 °C resulted in significant suppression of anammox activity, although this was rapidly recovered after the temperature was increased back to 15 °C. Analyses of 16S

  5. [Modifying effect of nitrites on pulmonary blastogenesis and viral leukogenesis in mice: role of nitric oxide and dioxide].

    Science.gov (United States)

    Il'nitskiĭ, A P; Reutov, V P; Ryzhova, N I; Kolpakova, A S; Deriagina, V P; Nekrasova, E A; Savluchinskaia, L A; Travkin, A G

    2000-01-01

    The long-term effects of sodium nitrite (NaNO2) on carcinogenesis induced by urethane (total dose 1.0 mg/g body weight) in low-grade cancer F1 (C57BLxCBA) and high-grade A/Snell mice and on viral (Rausher leukemia virus) leukomogenesis in Balb/c mice. The murine intake of NaNO2 with water (50 mg/l) causes a statistically significant increase in the number of adenomas in the lung. Examining the mechanism of conversion of NO2- to NO led to the assumption that the free radical compounds NO and NO2 are involved in the potentiating action of NO2 on blastomogenesis. The use of the oxidant emoxypine (3-hydroxypyridine) confirmed the above. The role of NO and NO2 in the intracellular processes under the modifying effects of nitrites and nitrates on blastomogenesis is analyzed.

  6. Simultaneous GC-ECNICI-MS measurement of nitrite, nitrate and creatinine in human urine and plasma in clinical settings.

    Science.gov (United States)

    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 (ONO2(-)) 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 (UNOxR) 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(-), ONO2(-), O(15)NO2(-), creatinine (do-Crea) and [methylo-(2)H3]creatinine (d3-Crea) in acetonic dilutions of native human urine and plasma samples (4:1, v/v) and their simultaneous quantification by GC-MS as PFBNO2, PFB(15)NO2, PFBONO2, PFBO(15)NO2, do-Crea-PFB and d3-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 (ONO2(-)), m/z 63 (O(15)NO2(-)), m/z 112 (do-Crea), and m/z 115 (d3-Crea). Retention times were 2.97min for PFB-ONO2/PFB-O(15)NO2, 3.1min for PFB-NO2/PFB-(15)NO2, and 6.7min for do-Crea-PFB/d3-Crea-PFB. We used this method to investigate the effects of long-term oral NaNO3 or NaCl (serving as placebo) supplementation (each 0.1mmol/kg body weight per day for 3 weeks) on creatinine excretion and UNOxR in 17 healthy young men

  7. Simultaneous determination of nitrite and nitrate ions by air-segmented amplitude-modulated multiplexed flow analysis.

    Science.gov (United States)

    Yoshida, Haruka; Inui, Koji; Takeuchi, Masaki; Tanaka, Hideji

    2012-01-01

    The concept of amplitude-modulated multiplexed flow analysis has been extended to the simultaneous determination of multiple analytes in a sample. A sample solution containing nitrite and nitrate ions is delivered from two channels, but the flow rates are varied at different frequencies. One of the channels has a reduction column for converting nitrate ions to nitrite ions. Downstream, the absorbance of the diazo-coupling product is monitored after the merging of both solutions with a Griess reagent. The signal is analyzed by a fast Fourier transform (FFT) in real time. From the thus-obtained amplitude, a µmol dm(-3) level of the ions can be determined. The introduction of air bubbles is effective to reduce any axial dispersion, and hence to improve the sensitivity.

  8. Estimation and correlative study of salivary nitrate and nitrite in tobacco related oral squamous carcinoma and submucous fibrosis

    Directory of Open Access Journals (Sweden)

    Vaishali Shende

    2013-01-01

    Oral submucous fibrosis (OSMF is a disease of the Indian subcontinent, which through immigration has a worldwide distribution. Betel nut chewing plays significant role in etiology of OSMF. The nut alkaloids have been shown experimentally to result in stimulation of collagen synthesis by fibroblasts in vitro, which can induce precancerous conditions. Materials and Methods: The present study was undertaken to detect nitrate and nitrite factor in saliva of cases with oral carcinoma, OSMF and normal individuals without any habits and to determine whether increased salivary nitrate and nitrite level is significant in oral carcinoma and submucous fibrosis using biochemical parameters. Conclusion: We conclude that the major inducer of oral squamous cell carcinoma (OSCC is exposure to tobacco. Recent studies have demonstrated that oxidative and nitrosative stress contributes to the development of oral carcinogenesis through deoxyribonucleic acid (DNA damage. Salivary composition of OSCC patients is substantially altered with respect to free radical-involved mechanisms.

  9. Combined Effect of Monoxide Hemoglobin and Sodium Nitrite on Physicochemical, Microbiological and Sensory Properties of Pork Sausage

    Directory of Open Access Journals (Sweden)

    Shengjiang Tan

    2014-03-01

    Full Text Available Sodium nitrite (NaNO2 faces a challenge in the meat industry because of its carcinogenicity. The studies about nitrite substitutes have attracted a considerable interest for many years. This study aims at the combined effects of monoxide hemoglobin (COHb and NaNO2 on physicochemical, microbiological and sensory properties of pork sausages. The addition of COHb led to the reductions in L*, b*, TBA, VBN and aerobic plate count as well as the increase in a* (p<0.05. The samples with 0.005% NaNO2 and 0.2% COHb addition had equal even better sensory color, flavor, mouthfeel and slice traits than those with 0.015% NaNO2 addition during storage. Moreover, such sample had less than 30 cfu/100 g Escherichia coli and no detectable Staphylococcus aureus during 29 days storage. Therefore, COHb showed a potential in the manufacture of sausages

  10. Investigating Sodium Nitrite Effect on Blood Nitric Oxide and Histopathologic Changes on Pulmonary Artery in Adult Male Rats

    Directory of Open Access Journals (Sweden)

    F Joibar

    2013-12-01

    Results: The outcome of nitric oxide plasmatic density measurement showed that nitric oxide level in animal ’s blood in 175 mg/kg/day dose recipient group and 350 mg/kg/day dose recipient group increased significantly compared with the control group at the level of P ≤ 0.05. Also thickness of media layer decreased in maximum dose group (350 mg/kg/day dose compared to the control group. Conclusion: Based on the results of different doses of sodium nitrite, the nitric oxide levels in the blood were increased, and the thickness of middle layer of the lung arteries at dose 350 mg of sodium nitrite was reduced.

  11. Defense Waste Processing Facility: Report of task force on options to mitigate the effect of nitrite on DWPF operations

    Energy Technology Data Exchange (ETDEWEB)

    Randall, D. (ed.); Marek, J.C.

    1992-03-01

    The possibility of accumulating ammonium nitrate (an explosive) as well as organic compounds in the DWPF Chemical Processing Cell Vent System was recently discovered. A task force was therefore organized to examine ways to avoid this potential hazard. Of thirty-two processing/engineering options screened, the task force recommended five options, deemed to have the highest technical certainty, for detailed development and evaluation: Radiolysis of nitrite in the tetraphenylborate precipitate slurry feed in a new corrosion-resistant facility. Construction of a Late Washing Facility for precipitate washing before transfer to the DWPF; Just-in-Time'' precipitation; Startup Workaround by radiolysis of nitrite in the existing corrosion-resistant Pump Pit tanks; Ammonia venting and organics separation in the DWPF; and, Estimated costs and schedules are included in this report.

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

    DEFF Research Database (Denmark)

    Gøtterup, Jacob; Olsen, Karsten; Knøchel, Susanne

    2008-01-01

    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...... 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 MbFeIINO in the different sausages and the colour stability during storage. Autofluorescence data correlated well...

  13. Formation of nitric oxide, ethyl nitrite and an oxathiolone derivative of caffeic acid in a mixture of saliva and white wine.

    Science.gov (United States)

    Takahama, Umeo; Tanaka, Mariko; Hirota, Sachiko

    2010-03-01

    Reactions of salivary nitrite with components of wine were studied using an acidic mixture of saliva and wine. The formation of nitric oxide (NO) in the stomach after drinking wine was observed. The formation of NO was also observed in the mixture (pH 3.6) of saliva and wine, which was prepared by washing the oral cavity with wine. A part of the NO formation in the stomach and the oral cavity was due to the reduction of salivary nitrite by caffeic and ferulic acids present in wine. Ethyl nitrite produced by the reaction of salivary nitrite and ethyl alcohol in wine also contributed to the formation of NO. In addition to the above reactions, caffeic acid in wine could be transformed to the oxathiolone derivative, which might have pharmacological functions. The results obtained in this study may help in understanding the effects of drinking wine on human health.

  14. Ammonia from iron(II) reduction of nitrite and the Strecker synthesis: do iron(II) and cyanide interfere with each other?

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  16. Sodium nitrite enhances generation of reactive oxygen species that decrease antioxidant power and inhibit plasma membrane redox system of human erythrocytes.

    Science.gov (United States)

    Ansari, Fariheen Aisha; Mahmood, Riaz

    2016-08-01

    Nitrite/nitrate salts are used in fertilizers and as food preservatives. Human exposure to high levels of nitrite results in its uptake and subsequent entry into blood where it can interact with erythrocytes. We show that treatment of human erythrocytes with sodium nitrite (NaNO2 ) results in a dose-dependent increase in the production of reactive oxygen species. This was accompanied by a decrease in the antioxidant power which lowered the free radical quenching and metal-reducing ability. NaNO2 treatment also inhibited plasma membrane redox system (PMRS) of erythrocytes. These changes increase the susceptibility of erythrocytes to oxidative damage, decrease the antioxidant power of whole blood, and can be a major cause of nitrite-induced cellular toxicity.

  17. Progress report on the evaluation of porous cathode for the electrochemical reduction of nitrates and nitrites in liquid wastes

    Energy Technology Data Exchange (ETDEWEB)

    Hobbs, D.T. [Westinghouse Savannah River Co., Aiken, SC (United States); Jha, K.; Weidner, J.W.; White, R.E. [South Carolina Univ., Columbia, SC (United States). Dept. of Chemical Engineering

    1995-12-27

    This report describes the experimental and modeling work performed to evaluate porous cathodes for the electrochemical reduction of nitrites in liquid wastes. The experiments were done using the MP{dagger} cell with two different porous cathodes: nickel foam and TySAR{trademark}SB{double_dagger}. The experimental results are compared with each other and to those obtained with a planar nickel cathode. The results show that the ammonia production reaction is the dominant cathodic reaction ({approximately}80% efficiency) for all three electrodes. The temperature range used in this study was 29-37 {circ}C while the catholyte feed was either 0.6M NaNO{sub 2} or 1.9M NaNO{sub 3}, both supported by a 1.33 M NaOH solution. All experiments used a constant current density of 0.25 A/cm{sup 2}. The experimental results suggest that the porous nickel electrode at lower temperatures ({approximately}31{circ}C) is the most efficient of the three electrodes for the reduction of nitrates and nitrites. The porous nickel electrode exhibited the highest conversion of nitrates and nitrites, and the lowest overpotential for a given current density. The partial current fractions at known catholyte concentrations were used to extract the exchange-current densities for the five cathodic reactions. Using these kinetic parameters, dynamic simulations of the four hour experiments were performed. Agreement was found between the model and experimental results for changes in the moles of the nitrate and nitrite and the cell overpotential with time. Future work will determine the effects of temperature and current densities on the exchange-current densities and reaction product distributions. The performance of other porous cathode materials (TySAR{trademark}EP{section}, TySAR{trademark}IM) will also be evaluated.

  18. Influence of Polysaccharide Krestin from Coriolus versicolor Extract on Nitrite and Malondialdehyde Concencentrations of Mus musculus Serum Exposed by Mycobacterium tuberculosis

    Directory of Open Access Journals (Sweden)

    Sri Puji Astuti Wahyuningsih

    2016-03-01

    Full Text Available Mycobacterium tuberculosis is a major infection agent of tuberculosis that is controlled by the response of cell-mediated immunity. It is macrophages and cytolytic T lymphocytes. Activated macrophages will produce free radicals. Excessive free radicals cause tissue damage. Polysaccharide krestin contains β-glucan. It is a scavenger of free radicals. This research aimed to identify the influence of polysaccharide krestin from C. versicolor on nitrite and malondialdehyde concentrations of mice serum exposed by M. tuberculosis. Nitrite concentration was determined by nitrite assay. Malondialdehyde concentration was determined by TBARS assay. The result showed that adding polysaccharide krestin before exposure (P1 and adding polysaccharide krestin before-after exposure (P3 had the best potential to decrease nitrite concentration. Nitrite concentrations of P1 and P3 were 1.364 ± 0.523 M and 1.456 ± 0.712 M respectively. Meanwhile, P1 group and adding polysaccharide krestin after exposure (P2 had the best potential to decrease malondialdehyde concentration. Malondialdehyde concentrations of P1 and P2 were 1125.86 ± 97.96 µM and 953.86 ± 328.16 µM respectively. Their nitrite and malondialdehyde concentrations decreased, compared to K and K- groups. The research conclusion was that adding polysaccharide krestin before exposure could decrease both nitrite and malondialdehyde concentrations.How to CiteWahyuningsih, S., Pramudya, M., & Sugiharto, S. (2016. Influence of Polysaccharide Krestin from Coriolus versicolor Extract on Nitrite and Malondialdehyde Concencentrations of Mus musculus Serum Exposed by Mycobacterium tuberculosis. Biosaintifika: Journal of Biology & Biology Education, 8(1, 12-17.

  19. Maternal characteristics associated with the dietary intake of nitrates, nitrites, and nitrosamines in women of child-bearing age: a cross-sectional study

    OpenAIRE

    Canfield Mark A; Romitti Paul A; McDonald Thomas J; Rene Antonio A; Huber John C; Steck Michelle D; Sharkey Joseph R; Brender Jean D; Griesenbeck John S; Langlois Peter H; Suarez Lucina

    2010-01-01

    Abstract 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 nitrosamine...

  20. Nitrite-Oxidizing Bacterium Nitrobacter winogradskyi Produces N-Acyl-Homoserine Lactone Autoinducers.

    Science.gov (United States)

    Mellbye, Brett L; Bottomley, Peter J; Sayavedra-Soto, Luis A

    2015-09-01

    Nitrobacter winogradskyi is a chemolithotrophic bacterium that plays a role in the nitrogen cycle by oxidizing nitrite to nitrate. Here, we demonstrate a functional N-acyl-homoserine lactone (acyl-HSL) synthase in this bacterium. The N. winogradskyi genome contains genes encoding a putative acyl-HSL autoinducer synthase (nwi0626, nwiI) and a putative acyl-HSL autoinducer receptor (nwi0627, nwiR) with amino acid sequences 38 to 78% identical to those in Rhodopseudomonas palustris and other Rhizobiales. Expression of nwiI and nwiR correlated with acyl-HSL production during culture. N. winogradskyi produces two distinct acyl-HSLs, N-decanoyl-l-homoserine lactone (C10-HSL) and a monounsaturated acyl-HSL (C10:1-HSL), in a cell-density- and growth phase-dependent manner, during batch and chemostat culture. The acyl-HSLs were detected by bioassay and identified by ultraperformance liquid chromatography with information-dependent acquisition mass spectrometry (UPLC-IDA-MS). The C=C bond in C10:1-HSL was confirmed by conversion into bromohydrin and detection by UPLC-IDA-MS.

  1. Characteristic of nitrous oxide production in partial denitrification process with high nitrite accumulation.

    Science.gov (United States)

    Du, Rui; Peng, Yongzhen; Cao, Shenbin; Wang, Shuying; Niu, Meng

    2016-03-01

    Nitrous oxide (N2O) production during the partial denitrification process with nitrate (NO3(-)-N) to nitrite (NO2(-)-N) transformation ratio of 80% was investigated in this study. Results showed that N2O was seldom observed before complete depletion of NO3(-)-N, but it was closely related to the reduction of NO2(-)-N rather than NO3(-)-N. High COD/NO3(-)-N was in favor of N2O production in partial denitrification with high NO2(-)-N accumulation. It was seriously enhanced at constant acidic pH due to the free nitrous acid (FNA) inhibition. However, the N2O production was much lower at initial pH of 5.5 and 6.5 due to the pH increase during denitrification process. Significantly, the pH turning point could be chosen as a controlled parameter to denote the end of NO3(-)-N reduction, which could not only achieve high NO2(-)-N accumulation but also decrease the N2O production significantly for practical application.

  2. EXHALED AND PLASMA NITRITE: a comparative study among healthy, cirrhotic and liver transplant patients

    Directory of Open Access Journals (Sweden)

    Viviane S AUGUSTO

    2014-03-01

    Full Text Available Context There is a relative lack of studies about exhaled nitrite (NO2- concentrations in cirrhotic and transplanted patients. Objective Verify possible differences and correlations between the levels of NO2-, measured in plasma and exhaled breath condensate collected from patients with cirrhosis and liver transplant. Method Sixty adult male patients, aged between 27 and 67 years, were subdivided into three groups: a control group comprised of 15 healthy volunteers, a cirrhosis group composed of 15 volunteers, and a transplant group comprised of 30 volunteers. The NO2- concentrations were measured by chemiluminescence. Results 1 The analysis of plasma NO2- held among the three groups showed no statistical significance. 2 The comparison between cirrhotic and control groups, control and transplanted and cirrhotic and transplanted was not statistically significant. 3 The measurements performed on of NO2- exhaled breath condensate among the three groups showed no statistical difference. 4 When comparing the control group samples and cirrhotic, control and transplanted and cirrhotic and transplanted, there was no significant changes in the concentrations of NO2-. Conclusion No correlations were found between plasma and exhaled NO2-, suggesting that the exhaled NO2- is more reflective of local respiratory NO release than the systemic circulation.

  3. The Corrosion Inhibition Characteristics of Sodium Nitrite Using an On-line Corrosion Rate Measurement System

    Energy Technology Data Exchange (ETDEWEB)

    Park, Mal-Yong; Kang, Dae-Jin [Korea Polytechnic University, Shiheung (Korea, Republic of); Moon, Jeon-Soo [Future Technology Research Laboratory, KEPCO Research Institute, Daejeon (Korea, Republic of)

    2015-04-15

    An on-line corrosion rate measurement system was developed using a personal computer, a data acquisition board and program, and a 2-electrode corrosion probe. Reliability of the developed system was confirmed with through comparison test. With this system, the effect of sodium nitrite (NaNO{sub 2}) as a corrosion inhibitor were studied on iron and aluminum brass that were immersed in sodium chloride (NaCl) solution. Corrosion rate was measured based on the linear polarization resistance method. The corrosion rates of aluminum brass and iron in 1% NaCl solutions were measured to be 0.290 mm per year (mmpy) and 0.2134 mmpy, respectively. With the addition of 200 ppm of NO{sub 2}{sup -}, the corrosion rates decreased to 0.0470 mmpy and 0.0254 mmpy. The addition of NO{sub 2}{sup -} caused a decrease in corrosion rates of both aluminum brass and iron, yet the NO{sub 2}{sup -} acted as a more effective corrosion inhibitor for iron. than aluminum brass.

  4. Ammonium removal by partial nitritation and Anammox processes from wastewater with increased salinity.

    Science.gov (United States)

    Malovanyy, Andriy; Plaza, Elzbieta; Trela, Jozef; Malovanyy, Myroslav

    2015-01-01

    This work is dedicated to the biological treatment of wastewater with increased salinity using a combination of partial nitritation and Anammox processes. Two one-stage deammonification moving bed biofilm reactors were operated with the increase in NaCl concentration every two weeks by 5 and 2.5 g/L. The strategy with a step of 5 g/L of salinity increase led to complete inhibition of the process at the salinity level of 15 g/L. The strategy with a step of 2.5 g/L gave possibility to adapt bacteria to the elevated salinity. After reaching the salinity level of 10 g NaCl/L, the reactor was operated during 92 days with a nitrogen removal rate of 0.39±0.19 g N/(m2·day) (0.078±0.038 kg N/m3·day) and an average nitrogen removal efficiency of 59%. It was shown that conductivity cannot be used for monitoring the process when a reactor is treating wastewater with increased salinity, whereas pH can be correlated to effluent ammonium concentration regardless of wastewater salinity.

  5. Aeration Strategies To Mitigate Nitrous Oxide Emissions from Single-Stage Nitritation/Anammox Reactors

    DEFF Research Database (Denmark)

    Domingo Felez, Carlos; Mutlu, A. Gizem; Jensen, Marlene Mark;

    2014-01-01

    -stage nitritation/anammox were operated under different aeration strategies, gradually adjusted over six months. At constant but limiting oxygen loading, synthetic reject water was fed (0.75g-N/L.d) and high nitrogen removal efficiencies (83 +/- 5 and 88 +/- 2%) obtained. Dynamics of liquid phase nitrous (N2O......) and nitric oxide (NO) concentrations were monitored and N2O emissions calculated. Significant decreases in N2O emissions were obtained when the frequency of aeration was increased while maintaining a constant air flow rate (from >6 to 1.7% Delta N2O/Delta TN). However, no significant effect on the emissions...... was noted when the duration of aeration was increased while decreasing air flow rate (10.9 +/- 3.2% Delta N2O/Delta TN). The extant ammonium oxidation activity (mgNH(4)(+)-N/gVSS.min) positively correlated with the specific N2O production rate (mgN(2)O-N/gVSS.min) of the systems. Operating under conditions...

  6. Performance of completely autotrophic nitrogen removal over nitrite process under different aeration modes and dissolved oxygen

    Institute of Scientific and Technical Information of China (English)

    Jinsong GUO; Guohong YANG; Fang FANG; Yu QIN

    2008-01-01

    In this study, three sequential batch biofilm reactors (SBBRs) were operated for 155 days to evaluate the performance of completely autotrophic nitrogen removal over nitrite (CANON) process under different aeration modes and dissolved oxygen (DO). Synthetic wastewater with 160-mg NH4+-N/L was fed into the reac-tors. In the continuously-aerated reactor, the efficiency of the ammonium nitrogen conversion and total nitrogen (TN) removal reached 80% and 70%, respectively, with DO between 0.8-1.0 mg/L. Whereas in the intermit-tently-aerated reactor, at the aeration/non-aeration ratio of 1.0, ammonium was always under the detection limit and 86% of TN was removed with DO between 2.0 2.5 mg/L during the aeration time. Results show that CANON could be achieved in both continuous and inter-mittent aeration pattern. However, to achieve the same nitrogen removal efficiency, the DO needed in the inter-mittently-aerated sequential batch biofilm reactor (SBBR) during the aeration period was higher than that in the continuously-aerated SBBR. In addition, the DO in the CANON system should be adjusted to the aeration mode, and low DO was not a prerequisite to CANON process.

  7. Novel pyridine containing ligands as models for the copper centres in nitrite reductase

    CERN Document Server

    Arnold, P J

    2001-01-01

    This thesis is concerned with the synthesis of a series of novel pyridine containing ligands and their copper co-ordination chemistry. The aim was to design ligands which would produce copper complexes which model the active sites within certain copper-containing Nitrite Reductase enzymes. The first chapter reviews previous work in this area and details the promising nature of pyridine-containing ligands. The remainder of this thesis is concerned with the synthesis and characterisation of some novel pyridine-containing ligands and their copper chemistry. The synthetic routes developed during this work enabled tris(pyrid-2-yl)methylamine ligands to be produced and studied which were tripodal in form but which had a primary amine group at the cap which could be further elaborated. Additional substituents were also placed on the pyridine rings to investigate their impact on the chemistry of their copper complexes. These ligands showed a variety, counter ion dependent chemistry. The structures of number of the co...

  8. Microbiology, ecology and application of the nitrite-dependent anaerobic methane oxidation process

    Directory of Open Access Journals (Sweden)

    Li-Dong eShen

    2012-07-01

    Full Text Available Nitrite-dependent anaerobic methane oxidation (n-damo, which couples the anaerobic oxidation of methane to denitrification, is a recently discovered process observed in Candidatus Methylomirabilis oxyfera. M. oxyfera is affiliated with the NC10 phylum, a phylum having no members in pure culture. Based on the isotopic labeling experiments, it is hypothesized that M. oxyfera has an unusual intra-aerobic pathway for the production of oxygen via the dismutation of nitric oxide into dinitrogen gas and oxygen. In addition, the bacterial species has a unique ultrastructure that is distinct from that of other previously described bacterial shapes. M. oxyfera-like sequences have been recovered from different natural habitats, suggesting that the n-damo process potentially contributes to global carbon and nitrogen cycles. The n-damo process is an ecological process that can reduce the greenhouse effect, as methane is more effective in heat-trapping than carbon dioxide. The n-damo process, which uses methane instead of organic matter to drive denitrification, is also an economical nitrogen removal process because methane is a relatively inexpensive electron donor. This mini-review summarizes the peculiar microbiology of M. oxyfera and discusses the potential ecological importance and engineering application of the n-damo process.

  9. Microbiology, ecology, and application of the nitrite-dependent anaerobic methane oxidation process.

    Science.gov (United States)

    Shen, Li-Dong; He, Zhan-Fei; Zhu, Qun; Chen, Dong-Qing; Lou, Li-Ping; Xu, Xiang-Yang; Zheng, Ping; Hu, Bao-Lan

    2012-01-01

    Nitrite-dependent anaerobic methane oxidation (n-damo), which couples the anaerobic oxidation of methane to denitrification, is a recently discovered process mediated by "Candidatus Methylomirabilis oxyfera." M. oxyfera is affiliated with the "NC10" phylum, a phylum having no members in pure culture. Based on the isotopic labeling experiments, it is hypothesized that M. oxyfera has an unusual intra-aerobic pathway for the production of oxygen via the dismutation of nitric oxide into dinitrogen gas and oxygen. In addition, the bacterial species has a unique ultrastructure that is distinct from that of other previously described microorganisms. M. oxyfera-like sequences have been recovered from different natural habitats, suggesting that the n-damo process potentially contributes to global carbon and nitrogen cycles. The n-damo process is a process that can reduce the greenhouse effect, as methane is more effective in heat-trapping than carbon dioxide. The n-damo process, which uses methane instead of organic matter to drive denitrification, is also an economical nitrogen removal process because methane is a relatively inexpensive electron donor. This mini-review summarizes the peculiar microbiology of M. oxyfera and discusses the potential ecological importance and engineering application of the n-damo process.

  10. Identifying N2O formation and emissions from a full-scale partial nitritation reactor.

    Science.gov (United States)

    Mampaey, Kris E; De Kreuk, Merle K; van Dongen, Udo G J M; van Loosdrecht, Mark C M; Volcke, Eveline I P

    2016-01-01

    In this study, N2O formation and emissions from a full-scale partial nitritation (SHARON) reactor were identified through a three-weeks monitoring campaign during which the off-gas was analysed for N2O, O2, CO2 and NO. The overall N2O emission was 3.7% of the incoming ammonium load. By fitting the N2O emission to a theoretical gas stripping profile, the N2O emissions could be assigned to aerobically formed N2O and N2O formed under anoxic conditions. This was further substantiated by liquid N2O measurements. Under standard operation, 70% of the N2O emission was attributed to anoxic N2O formation. Dedicated experiments revealed that low dissolved oxygen concentrations (<1.0 gO2·m(-3)) and longer anoxic periods resulted in an increased N2O emission. Minimising or avoiding anoxic conditions has the highest effect in lowering the N2O emissions. As an additional result, the use of the off-gas N2O concentration measurements to monitor the gas-liquid mass transfer rate coefficient (kLa) during dynamic reactor operation was demonstrated.

  11. Effect of Dry Goji Berry and Pumpkin Powder on Quality of Cooked and Smoked Beef with Reduced Nitrite Content

    Directory of Open Access Journals (Sweden)

    Mira S. Serikkaisai

    2014-07-01

    Full Text Available The colorant and antioxidant activity of dried fruits of Goji Berry (GB (Lycium chinense and/or butternut Pumpkin Powder (PP (Cucurbita moschata can be used for reduction of part of nitrites in cooked and smoked meat products. Since many of these natural biological active substances are consumed together and probably have the potential for synergistic interactions. The objective of this study was to establishe the potential of to concentrations 0.5 and 1.0% of GB and/or PP separately or in combinations, as additives for processing of cooked and smoked beef striploin with 1/2 reduced nitrite content. The separate use of GB or PP leads to certain abnormalities in sensory quality and technological properties but the addition to the pikle a combination containing 1.0% of GB and 0.5% PP guarantee good quality, nise sensory properties and colour characteristics and inhibite the oxidative changes in cooked and smoked beef striploin with a half reduced amounts of nitrites.

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

    Science.gov (United States)

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

    2016-11-25

    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.

  13. Garlic oil as a modulating agent for oxidative stress and neurotoxicity induced by sodium nitrite in male albino rats.

    Science.gov (United States)

    Hassan, Hanaa A; Hafez, Hani S; Zeghebar, Fawzia E

    2010-07-01

    In the present study, we investigated the neurobiochemical alterations and oxidative stress induced by food preservative; sodium nitrite (NaNO2) as well as the role of the garlic oil in amelioration of the neurotoxicity in male albino rats. Serum and brain homogenates of the rats received NaNO2 (80 mg/kg body weight) for 3 months exhibited significant decrease in acetylcholine esterase (AChE) activity as well as the levels of phospholipids, total protein and the endogenous antioxidant system (glutathione; GSH and superoxide dismutase; SOD). In contrast, lactic dehydrogenase (LDH) activity, brain thiobarbituric acid reactive substances (TBARS) and nitric oxide (NO) levels were significantly increased. On the other hand, the oral administration of garlic oil (5 ml/kg body weight) daily for 3 months significantly improved the neurobiochemical disorders and inhibited the oxidative stress induced by NaNO2 ingestion. So, this study reveals the neural toxic effects of NaNO2 by exerting oxidative stress and retrograde the endogenous antioxidant system. However, garlic oil has a promising role in attenuating the obtained hazard effects of sodium nitrite by its high antioxidant properties which may eventually be related with the preservation of SOD activity and primary mitochondrial role against nitrite-induced neurotoxicity in rats.

  14. Influence of seasonal temperature fluctuations on two different partial nitritation-anammox reactors treating mainstream municipal wastewater.

    Science.gov (United States)

    Lackner, Susanne; Welker, Samuel; Gilbert, Eva M; Horn, Harald

    2015-01-01

    Partial nitritation-anammox (PN-A) has gained increasing interest for municipal wastewater treatment in recent years due to its high energy-saving potential. Moving the PN-A technology from side- to mainstream exhibited a set of challenges. Conditions are quite different, with much lower ammonium concentrations and temperatures. Biomass retention becomes highly important due to the even lower growth rates. This study compared two laboratory-scale reactors, a sequencing batch reactor (SBR) and a moving bed biofilm reactor (MBBR), employing realistic seasonal temperature variations over a 1-year period. The results revealed that both systems had to face decreasing ammonium conversion rates and nitrite accumulation at temperatures lower than 12°C. The SBR did not recover from the loss in anammox activity even when the temperature increased again. The MBBR only showed a short nitrite peak and recovered its initial ammonium turnover when the temperature rose back to >15°C. The SBR had higher biomass specific rates, indicating that suspended sludge is less diffusion-limited but also more susceptible to biomass wash-out. However, the MBBR showed the more stable performance also at low temperatures and managed to recover. Ex situ batch activity tests supported reactor operation data by providing additional insight with respect to specific biomass activities.

  15. Analysis of gene expression changes, caused by exposure to nitrite, in metabolic and antioxidant enzymes in the red claw crayfish, Cherax quadricarinatus.

    Science.gov (United States)

    Jiang, Qichen; Zhang, Wenyi; Tan, Hongyue; Pan, Dongmei; Yang, Yuanhao; Ren, Qian; Yang, Jiaxin

    2014-06-01

    We evaluated the effect of acute exposure to nitrite on expression of antioxidant and metabolic enzyme genes in gill tissue of advanced juvenile Cherax quadricarinatus. A 48h nitrite exposure was conducted, using four test concentrations (NO2-N=0.5, 1, 1.5 and 2mg L(-1)) plus a control group. The relative mRNA expression of mitochondrial manganese superoxide dismutase (mMnSOD), cytosolic MnSOD (cMnSOD), extracellular copper/zinc SOD (exCu/ZnSOD), catalase (CAT), glutathione S-transferase (GST), arginine kinase (AK), glutamate dehydrogenase (GDH), mitochondrial malate dehydrogenase (mMDH), Na(+)/K(+)-ATPase α-subunit and phosphoenolpyruvate carboxykinase (PEPCK) in gill tissue was measured. Significantly increased mRNA expression was observed for all the antioxidant enzymes after 12 and 24h. After 48h, they all decreased at high nitrite concentrations. The gene expression levels of AK, GDH, mMDH and Na(+)/K(+)-ATPase α-subunit showed similar trends as the antioxidant enzymes. Significant depression of gene expression levels of PEPCK occurred throughout the experimental time at high nitrite concentrations. The results indicated that nitrite could induce oxidative and metabolic stress in C. quadricarinatus, in a time dependent manner, which suggests they could be helpful in predicting sublethal nitrite toxicity and useful in environmental monitoring studies.

  16. Polymeric optical sensors for selective and sensitive nitrite detection using cobalt(III) corrole and rhodium(III) porphyrin as ionophores

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Si; Wo, Yaqi; Meyerhoff, Mark E., E-mail: mmeyerho@umich.edu

    2014-09-16

    Highlights: • We examine cobalt(III) corroles and rhodium(III) porphyrins as ionophores in polymeric films for optical sensors to detect nitrite. • Different types of proton chromoionophores are evaluated to optimize nitrite response. • Selectivity over lipophilic anions such as perchlorate and thiocyanate is observed. • Both ionophores yield optical sensors that are fully reversible. • The cobalt(III) corrole based sensor is employed to determine nitric oxide emission rates from NO donor doped polymers with good accuracy. - Abstract: Cobalt(III) 5,10,15-tris(4-tert-butylphenyl) corrole with a triphenylphosphine axial ligand and rhodium(III) 5,10,15,20-tetra(p-tert-butylphenyl) porphyrin are incorporated into plasticized poly(vinyl chloride) films to fabricate nitrite-selective bulk optodes via absorbance measurements. The resulting films yield sensitive, fast and fully reversible response toward nitrite with significantly enhanced nitrite selectivity over other anions including lipophilic anions such as thiocyanate and perchlorate. The selectivity patterns differ greatly from the Hofmeister series based on anion lipophilicity and are consistent with selectivity obtained with potentiometric sensors based on the same ionophores. The optical nitrite sensors are shown to be useful for detecting rates of emission of nitric oxide (NO) from NO releasing polymers containing S-nitroso-N-acetyl-DL-penicillamine.

  17. Effect of high oral doses of nitrate on salivary recirculation of nitrates and nitrites and on bacterial diversity in the saliva of young pigs.

    Science.gov (United States)

    Trevisi, P; Casini, L; Nisi, I; Messori, S; Bosi, P

    2011-04-01

    Ingested nitrate is absorbed in the small intestine, recirculated into the saliva and reduced to nitrite by oral bacteria. In pigs receiving a moderate dietary addition of nitrate, the recirculation into the saliva is modest, so we aimed to assess the effect of higher nitrate doses to find out how the animal reacts to this new situation and to evaluate if a higher nitrate level could enhance the nitrate reduction process, improving the nitrite production Trial 1. Six piglets received 100 g of a commercial diet with 2.45% KNO(3) . In relation to baseline values, nitrate in blood serum and saliva increased 15 times, and declined after 6 h vs. 2 h. Salivary nitrite increased seven times after the addition and declined after 6 h vs. 2 h. Trial 2. Six piglets were fed a diet with or without 1.22% KNO(3) for 2 weeks. Salivary nitrate and nitrite increased with the addition of KNO3: nitrate increased from d0 to the end of the trial, nitrite increased 15 times after 1 week, but decreased after 2 weeks to 4.5-fold the control. After 2 weeks, nitrate reduced Shan diversity index of salivary microbiota. The present results indicate that the long exposure to high quantities of nitrates impairs the oral reduction of nitrate to nitrite and engenders a reduction of the mouth's microbiota diversity.

  18. The Determination of Nitrate and Nitrite in Human Urine and Blood by High-Performance Liquid Chromatography and Cloud-Point Extraction.

    Science.gov (United States)

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

    2015-08-01

    A simple efficient and practical separation/preconcentration coupled with HPLC method for the determination nitrate and low concentrations of nitrite in human urine and blood was investigated. The method is based on precolumn derivatization using the Griess reaction and cloud-point extraction (CPE) of nitrite anion and direct determination of nitrate using its UV absorbance by ion-pair HPLC. The chromatographic process with detection at two wavelengths (510 and 220 nm) allows the determination of nitrite and nitrate. Decolorization and protein precipitation of urine and blood was applied to overcome the interference of matrix and enhance the sensitivity. The method was validated for linearity, accuracy and precision. Under the optimum conditions, the linear range of nitrite from 10 to 1,000 ng/mL and nitrate from 0.1 to 10 µg/mL. Product recoveries ranged from 92.4 to 99.9%. The limits of detection were 1 ng/mL and 0.1 µg/mL for nitrite and nitrate, respectively. Therefore, the technique was simple and reliable, with potential application in biological sample analysis of nitrate and nitrite.

  19. Nitrite to nitrate molar ratio is inversely proportional to oxidative cell damages and granulocytic apoptosis at the wound site following cutaneous injury in rats.

    Science.gov (United States)

    Zunić, Gordana; Colić, Miodrag; Vuceljić, Marina

    2009-06-01

    Nitric oxide (NO) metabolism in response to the inflammatory cell infiltration and their apoptosis at the wound site, using a model of subcutaneously implanted sponges in Albino Oxford rats, were examined. The injured animals were sacrificed at days 1, 2 and 3 after the injury. Nitrites, nitrates (final products of NO metabolism), malondialdehyde (an indicator of oxidative cell damages), urea (product of arginase activity) and other parameters were measured both in plasma and wound fluid samples. Nitrite to nitrate molar ratio and sum of nitrites and nitrates (NO(x)) were calculated. The total cell numbers were at similar level throughout the examined period, but a gradual decrease of viable granulocytes, mainly due to the increased apoptosis, and the increase of monocyte-macrophage number occurred after the second day. A gradual increase of wound fluid nitrates, NO(x) and malondialdehyde suggested the increases of both NO and free oxygen radicals production. Interestingly, wound fluid nitrites peaked at the first day decreasing to the corresponding plasma levels thereafter. Wound fluid nitrite to nitrate molar ratio gradually decreased and negatively correlated both with the number of apoptotic cells (r= -0.752, poxidative cell damages and cell apoptosis at the wound site early after the cutaneous wound. Moreover, the obtained findings suggest that measurement of both nitrites and nitrates contribute to better insight into overall wound NO metabolism.

  20. Oxidation of Fe(II)-EDTA by nitrite and by two nitrate-reducing Fe(II)-oxidizing Acidovorax strains.

    Science.gov (United States)

    Klueglein, N; Picardal, F; Zedda, M; Zwiener, C; Kappler, A

    2015-03-01

    The enzymatic oxidation of Fe(II) by nitrate-reducing bacteria was first suggested about two decades ago. It has since been found that most strains are mixotrophic and need an additional organic co-substrate for complete and prolonged Fe(II) oxidation. Research during the last few years has tried to determine to what extent the observed Fe(II) oxidation is driven enzymatically, or abiotically by nitrite produced during heterotrophic denitrification. A recent study reported that nitrite was not able to oxidize Fe(II)-EDTA abiotically, but the addition of the mixotrophic nitrate-reducing Fe(II)-oxidizer, Acidovorax sp. strain 2AN, led to Fe(II) oxidation (Chakraborty & Picardal, 2013). This, along with other results of that study, was used to argue that Fe(II) oxidation in strain 2AN was enzymatically catalyzed. However, the absence of abiotic Fe(II)-EDTA oxidation by nitrite reported in that study contrasts with previously published data. We have repeated the abiotic and biotic experiments and observed rapid abiotic oxidation of Fe(II)-EDTA by nitrite, resulting in the formation of Fe(III)-EDTA and the green Fe(II)-EDTA-NO complex. Additionally, we found that cultivating the Acidovorax strains BoFeN1 and 2AN with 10 mM nitrate, 5 mm acetate, and approximately 10 mM Fe(II)-EDTA resulted only in incomplete Fe(II)-EDTA oxidation of 47-71%. Cultures of strain BoFeN1 turned green (due to the presence of Fe(II)-EDTA-NO) and the green color persisted over the course of the experiments, whereas strain 2AN was able to further oxidize the Fe(II)-EDTA-NO complex. Our work shows that the two used Acidovorax strains behave very differently in their ability to deal with toxic effects of Fe-EDTA species and the further reduction of the Fe(II)-EDTA-NO nitrosyl complex. Although the enzymatic oxidation of Fe(II) cannot be ruled out, this study underlines the importance of nitrite in nitrate-reducing Fe(II)- and Fe(II)-EDTA-oxidizing cultures and demonstrates that Fe(II)-EDTA cannot

  1. A facile fabrication of copper particle-decorated novel graphene flower composites for enhanced detecting of nitrite.

    Science.gov (United States)

    Wang, Huiwen; Wang, Caiqin; Yang, Beibei; Zhai, Chunyang; Bin, Duan; Zhang, Ke; Yang, Ping; Du, Yukou

    2015-02-21

    We describe a simple electrochemical preparation method of a novel three dimensional (3D) graphene material, porous flower-like reduced graphene oxide (f-RGO) nanosheets, which was explored as the support for Cu particles on a glassy carbon electrode (Cu/f-RGO/GCE) for detecting nitrite. In morphology studies, scanning electron microscopy (SEM) demonstrates the 3D porous structure of f-RGO enlarges the surface area of the electrode and promotes more Cu particles depositing on the surface of f-RGO with homogeneous dispersion. In cyclic voltammetry (CV), a well-defined voltammetric peak along with the remarkable reduction current indicates excellent electrocatalytic activity of the Cu/f-RGO/GCE for NaNO2 reduction compared with other corresponding electrodes. The effects of pH value and detection potential on the current responses of Cu/f-RGO/GCE towards nitrite were optimized to obtain the maximal sensitivity. In the optimal experimental conditions, Cu/f-RGO/GCE displays the wide detection range from 0.15 μM to 10,500 μM and the low limit of detection of 0.06 μM (S/N = 3) with fast response time 2 s for detecting NaNO2 through an amperometric method. Furthermore, the presence of K(+), Na(+), Cl(-), NH4(+), NO3(-), SO4(2-) and ascorbic acid show a negligible effect on the current response of nitrite determination suggesting Cu/f-RGO/GCE have the high selectivity for detecting nitrite even in the presence of high concentration of interferents. Moreover, the real sample determination experiment indicated practical feasibility of the obtained sensor. The prepared sensor for determination of NaNO2 exhibited wide liner range, low detection limit, good reproducibility, nice stability and remarkable anti-interference ability. In this paper, not only did the Cu/f-RGO/GCE show high performance for determination of nitrite, but also it was simple to prepare, user-friendly and cost-effective.

  2. Survival of Listeria innocua in dry fermented sausages and changes in the typical microbiota and volatile profile as affected by the concentration of nitrate and nitrite.

    Science.gov (United States)

    Hospital, Xavier F; Hierro, Eva; Fernández, Manuela

    2012-02-15

    The involvement of nitrate and nitrite in the formation of N-nitrosamines in foods is a matter of great concern. This situation has led to revise the real amount of nitrate and nitrite needed in meat products to exert proper technological and safety activities, and also to extensive research to find alternatives to their use. The present study addresses the possibility of reducing the ingoing amounts of these additives below the legal limits established by the current European regulations. Different concentrations of nitrate and nitrite were tested on Spanish salchichón-type dry fermented sausages concerning their role in the microbiota and volatile profile. Sausages were manufactured with the maximum ingoing amounts established by the EU regulations (150 ppm NaNO(3) and 150 ppm NaNO(2)), a 25% reduction and a 50% reduction; control sausages with no nitrate/nitrite addition were also prepared. The mixtures were inoculated with 5 log cfu/g of Listeria innocua as a surrogate for Listeria monocytogenes. L. innocua numbers in the final product were approximately 1.5 log cfu/g lower in the batch with the maximum nitrate/nitrite concentration when compared to 25 and 50% reduced batches, and about 2 log cfu/g in comparison to the control sausages. The final numbers of catalase-positive cocci were 1 log cfu/g higher in the 50% nitrate/nitrite reduced batch and 2 log cfu/g higher in the control sausages, compared to products manufactured with the maximum nitrate/nitrite concentration. This increase was related to a higher amount of volatile compounds derived from carbohydrate fermentation and amino acid degradation. Sausages with no addition of nitrate/nitrite showed higher amount of volatiles from lipid oxidation. Enterobacteriaceae counts reached detectable values (1-2 log cfu/g) in both nitrate/nitrite reduced sausages and in the control batch, while these organisms were not detected in the batch with the maximum ingoing amount. Nitrate and nitrite exerted a significant

  3. Glycine propionyl-L-carnitine increases plasma nitrate/nitrite in resistance trained men

    Directory of Open Access Journals (Sweden)

    Smith Webb A

    2007-12-01

    Full Text Available Abstract We have recently demonstrated that oral intake of glycine propionyl-L-carnitine (GPLC increases plasma nitrate/nitrite (NOx, a surrogate measure of nitric oxide production. However, these findings were observed at rest, and in previously sedentary subjects. Purpose In the present study, we sought to determine the impact of oral GPLC on plasma NOx at rest and in response to a period of reactive hyperemia in resistance trained men. Methods Using a double blind, crossover design, 15 healthy men (24 ± 4 years were assigned to GPLC (3 g/d PLC + 1044 mg glycine and a placebo in random order, for a four-week period, with a two-week washout between condition assignment. Blood samples were taken from subjects at rest and at 0, 3, and 10 minutes following an ischemia-reperfusion protocol (six minutes of upper arm cuff occlusion at 200 mmHg followed by rapid reperfusion with cuff removal. Blood samples were taken from a forearm vein from the same arm used for the protocol and analyzed for total nitrate/nitrite. Data are presented as mean ± SEM. Results A condition main effect (p = 0.0008 was noted for NOx, with higher values in subjects when using GPLC (45.6 ± 2.8 μmol·L-1 compared to placebo (34.9 ± 1.2 μmol·L-1. No time main effect was noted (p = 0.7099, although values increased approximately 12% from rest (37.7 ± 2.7 μmol·L-1 to a peak at 10 minutes post protocol (42.3 ± 3.3 μmol·L-1. The interaction effect was not significant (p = 0.8809, although paired time contrasts revealed higher values for GPLC compared to placebo at 3 (48.2 ± 6.7 vs. 34.9 ± 2.4 μmol·L-1; p = 0.033 and 10 (48.8 ± 5.9 vs. 35.7 ± 2.1 μmol·L-1; p = 0.036 minutes post protocol, with non-statistically significant differences noted at rest (41.8 ± 4.5 vs. 33.6 ± 2.5 μmol·L-1; p = 0.189 and at 0 minutes (43.6 ± 5.1 vs. 35.4 ± 2.7 μmol·L-1; p = 0.187 post protocol. An analysis by subject (collapsed across time indicated that 11 of the 15 subjects

  4. Origin and fate of the secondary nitrite maximum in the Arabian Sea

    Directory of Open Access Journals (Sweden)

    P. Lam

    2011-03-01

    Full Text Available The Arabian Sea harbours one of the three major oxygen minimum zones (OMZs in the world's oceans, and it alone is estimated to account for ~10–20% of global oceanic nitrogen (N loss. While actual rate measurements have been few, the consistently high accumulation of nitrite (NO2 coinciding with suboxic conditions in the central-northeastern part of the Arabian Sea has led to the general belief that this is the region where active N-loss takes place. Most subsequent field studies on N-loss have thus been drawn almost exclusively to the central-NE. However, a recent study measured only low to undetectable N-loss activities in this region, compared to orders of magnitude higher rates measured towards the Omani shelf where little NO2 accumulated (Jensen et al., 2011. In this paper, we further explore this discrepancy by comparing the NO2 producing and consuming processes, and examining the relationship between the overall NO2 balance and active N-loss in the Arabian Sea. Based on a combination of 15N-incubation experiments, functional gene expression analyses, nutrient profiling and flux modeling, our results showed that NO2 accumulated in the Central-NE Arabian Sea due to a net production via primarily active nitrate (NO3 reduction and to a certain extent ammonia oxidation. Meanwhile, NO2 consumption via anammox, denitrification and dissimilatory nitrate/nitrite reduction to ammonium (NH4+ were hardly detectable in this region, though some loss to NO2 oxidation was predicted from modeled NO3 changes. No significant correlation was found between NO2 and N-loss rates (p>0.05. This discrepancy between NO2 accumulation and lack of active N

  5. Origin and fate of the secondary nitrite maximum in the Arabian Sea

    Directory of Open Access Journals (Sweden)

    P. Lam

    2011-06-01

    Full Text Available The Arabian Sea harbours one of the three major oxygen minimum zones (OMZs in the world's oceans, and it alone is estimated to account for ~10–20 % of global oceanic nitrogen (N loss. While actual rate measurements have been few, the consistently high accumulation of nitrite (NO2 coinciding with suboxic conditions in the central-northeastern part of the Arabian Sea has led to the general belief that this is the region where active N-loss takes place. Most subsequent field studies on N-loss have thus been drawn almost exclusively to the central-NE. However, a recent study measured only low to undetectable N-loss activities in this region, compared to orders of magnitude higher rates measured towards the Omani Shelf where little NO2 accumulated (Jensen et al., 2011. In this paper, we further explore this discrepancy by comparing the NO2-producing and consuming processes, and examining the relationship between the overall NO2 balance and active N-loss in the Arabian Sea. Based on a combination of 15N-incubation experiments, functional gene expression analyses, nutrient profiling and flux modeling, our results showed that NO2 accumulated in the central-NE Arabian Sea due to a net production via primarily active nitrate (NO3 reduction and to a certain extent ammonia oxidation. Meanwhile, NO2 consumption via anammox, denitrification and dissimilatory nitrate/nitrite reduction to ammonium (NH4+ were hardly detectable in this region, though some loss to NO2 oxidation was predicted from modeled NO3 changes. No significant correlation was found between NO2 and N-loss rates (p>0.05. This discrepancy between NO2 accumulation and lack of active N

  6. Nitrate and nitrite inhibition of methanogenesis during denitrification in granular biofilms and digested domestic sludges.

    Science.gov (United States)

    Banihani, Qais; Sierra-Alvarez, Reyes; Field, James A

    2009-11-01

    Anaerobic bioreactors that can support simultaneous microbial processes of denitrification and methanogenesis are of interest to nutrient nitrogen removal. However, an important concern is the potential toxicity of nitrate (NO(3) (-)) and nitrite (NO(2) (-)) to methanogenesis. The methanogenic toxicity of the NO (x) (-) compounds to anaerobic granular biofilms and municipal anaerobic digested sludge with two types of substrates, acetate and hydrogen, was studied. The inhibition was the severest when the NO (x) (-) compounds were still present in the media (exposure period). During this period, 95% or greater inhibition of methanogenesis was evident at the lowest concentrations of added NO(2) (-) tested (7.6-10.2 mg NO(2) (-)-N l(-1)) or 8.3-121 mg NO(3) (-)-N l(-1) of added NO(3) (-), depending on substrate and inoculum source. The inhibition imparted by NO(3) (-) was not due directly to NO(3) (-) itself, but instead due to reduced intermediates (e.g., NO(2) (-)) formed during the denitrification process. The toxicity of NO (x) (-) was found to be reversible after the exposure period. The recovery of activity was nearly complete at low added NO (x) (-) concentrations; whereas the recovery was only partial at high added NO (x) (-) concentrations. The recovery is attributed to the metabolism of the NO (x) (-) compounds. The assay substrate had a large impact on the rate of NO(2) (-) metabolism. Hydrogen reduced NO(2) (-) slowly such that NO(2) (-) accumulated more and as a result, the toxicity was greater compared to acetate as a substrate. The final methane yield was inversely proportional to the amount of NO (x) (-) compounds added indicating that they were the preferred electron acceptors compared to methanogenesis.

  7. Potentially fatal new trend in performance enhancement: a cautionary note on nitrite

    Directory of Open Access Journals (Sweden)

    Naughton Declan P

    2010-06-01

    Full Text Available Abstract Background Considerable interest has been shown by athletes and scientists in the potential for nitric oxide and associated vasodilators to enhance performance. This study aims to explore potential misuse of vasodilators by the athletes, and to highlight the growing concern over these agents. Methods Retrospective analyses of anonymous inquiries recorded in the Drug Information Database™ (DID™ between January 2006 and June 2008 (inclusive. In this 30-month period, the DID™ recorded 198,023 inquiries, of which 118,724 were UK Licensed Pharmaceutical products with a further 79,299 inquiries made for substance not found in the database. Results Phosphodiesterase type 5 (PDE-5 inhibitors, dominated by Viagra®, ranked 16th among the substance groups. The proportion of the inquiries made regarding PDE-5 inhibitors, especially in comparison to antibiotics, painkillers or alcohol, appears to be above the level that would normally be expected from medical need. No significant change in the months leading up to the Beijing Olympics was observed. On the contrary, the Nitric/Nitrate group showed a notable increase between 2006-2007 and 2008, suggesting a potential increase in interest in using nitric oxide among athletes. Conclusions With patents recently filed for the use of agents containing sodium nitrite/nitrate to enhance blood flow for performance enhancement in sport, coupled with anecdotal evidence from internet athlete forums and media, there is a concern that athletes may endanger their health by using vasodilators to enhance athletic performance. PDE-5 inhibitors or chemicals in the nitrate/nitrate group are currently not prohibited or tested for by the doping control agencies but some are highly dangerous to health and can lead to cardiovascular collapse, coma and death. Its promotion among athletes as a performance enhancing supplement is ethically and medically questionable.

  8. Anaerobic methane oxidation coupled to nitrite reduction can be a potential methane sink in coastal environments.

    Science.gov (United States)

    Shen, Li-Dong; Hu, Bao-Lan; Liu, Shuai; Chai, Xiao-Ping; He, Zhan-Fei; Ren, Hong-Xing; Liu, Yan; Geng, Sha; Wang, Wei; Tang, Jing-Liang; Wang, Yi-Ming; Lou, Li-Ping; Xu, Xiang-Yang; Zheng, Ping

    2016-08-01

    In the current study, we investigated nitrite-dependent anaerobic methane oxidation (N-DAMO) as a potential methane sink in the Hangzhou Bay and the adjacent Zhoushan sea area. The potential activity of the N-DAMO process was primarily observed in Hangzhou Bay by means of (13)C-labeling experiments, whereas very low or no potential N-DAMO activity could be detected in the Zhoushan sea area. The measured potential N-DAMO rates ranged from 0.2 to 1.3 nmol (13)CO2 g(-1) (dry sediment) day(-1), and the N-DAMO potentially contributed 2.0-9.4 % to the total microbial methane oxidation in the examined sediments. This indicated that the N-DAMO process may be an alternative pathway in the coastal methane cycle. Phylogenetic analyses confirmed the presence of Candidatus Methylomirabilis oxyfera-like bacteria in all the examined sediments, while the group A members (the dominant bacteria responsible for N-DAMO) were found mainly in Hangzhou Bay. Quantitative PCR showed that the 16S rRNA gene abundance of Candidatus M. oxyfera-like bacteria varied from 5.4 × 10(6) to 5.0 × 10(7) copies g(-1) (dry sediment), with a higher abundance observed in Hangzhou Bay. In addition, the overlying water NO3 (-) concentration and salinity were identified as the most important factors influencing the abundance and potential activity of Candidatus M. oxyfera-like bacteria in the examined sediments. This study showed the evidence of N-DAMO in coastal environments and indicated the importance of N-DAMO as a potential methane sink in coastal environments.

  9. 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.

    Science.gov (United States)

    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.

  10. Plasma nitrate and nitrite are increased by a high-nitrate supplement but not by high-nitrate foods in older adults.

    Science.gov (United States)

    Miller, Gary D; Marsh, Anthony P; Dove, Robin W; Beavers, Daniel; Presley, Tennille; Helms, Christine; Bechtold, Erika; King, S Bruce; Kim-Shapiro, Daniel

    2012-03-01

    Little is known about the effect of dietary nitrate on the nitrate/nitrite/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 4-period crossover controlled design. We hypothesized that the high-nitrate diet would show higher levels of plasma nitrate/nitrite and lower blood pressure compared with the control diet, which would be potentiated by the supplement. Participants were 8 normotensive older men and women (5 female, 3 male, 72.5 ± 4.7 years old) with no overt disease or medications that affect nitric oxide metabolism. Plasma nitrate and nitrite levels and blood pressure were measured before 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 < .001 and P = .017 for nitrate and nitrite, respectively) and high-nitrate diet + supplement (P = .001 and P = .002), but not for control diet (P = .713 and P = .741) or high-nitrate diet (P = .852 and P = .500). Blood pressure decreased from the morning baseline measure to the three 2-hour postmeal 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.

  11. Identification of nitrite-reducing bacteria using sequential mRNA fluorescence in situ hybridization and fluorescence-assisted cell sorting.

    Science.gov (United States)

    Mota, Cesar R; So, Mark Jason; de los Reyes, Francis L

    2012-07-01

    Sequential mRNA fluorescence in situ hybridization (mRNA FISH) and fluorescence-assisted cell sorting (SmRFF) was used for the identification of nitrite-reducing bacteria in mixed microbial communities. An oligonucleotide probe labeled with horseradish peroxidase (HRP) was used to target mRNA of nirS, the gene that encodes nitrite reductase, the enzyme responsible for the dissimilatory reduction of nitrite to nitric oxide. Clones for nirS expression were constructed and used to provide proof of concept for the SmRFF method. In addition, cells from pure cultures of Pseudomonas stutzeri and denitrifying activated sludge were hybridized with the HRP probe, and tyramide signal amplification was performed, conferring a strongly fluorescent signal to cells containing nirS mRNA. Flow cytometry-assisted cell sorting was used to detect and physically separate two subgroups from a mixed microbial community: non-fluorescent cells and an enrichment of fluorescent, nitrite-reducing cells. Denaturing gradient gel electrophoresis (DGGE) and subsequent sequencing of 16S ribosomal RNA (rRNA) genes were used to compare the fragments amplified from the two sorted subgroups. Sequences from bands isolated from DGGE profiles suggested that the dominant, active nitrite reducers were closely related to Acidovorax BSB421. Furthermore, following mRNA FISH detection of nitrite-reducing bacteria, 16S rRNA FISH was used to detect ammonia-oxidizing and nitrite-oxidizing bacteria on the same activated sludge sample. We believe that the molecular approach described can be useful as a tool to help address the longstanding challenge of linking function to identity in natural and engineered habitats.

  12. Enzyme-level interconversion of nitrate and nitrite in the fall mixed layer of the Antarctic Ocean

    Science.gov (United States)

    Kemeny, P. C.; Weigand, M. A.; Zhang, R.; Carter, B. R.; Karsh, K. L.; Fawcett, S. E.; Sigman, D. M.

    2016-07-01

    In the Southern Ocean, the nitrogen (N) isotopes of organic matter and the N and oxygen (O) isotopes of nitrate (NO3-) have been used to investigate NO3- assimilation and N cycling in the summertime period of phytoplankton growth, both today and in the past. However, recent studies indicate the significance of processes in other seasons for producing the annual cycle of N isotope changes. This study explores the impact of fall conditions on the 15N/14N (δ15N) and 18O/16O (δ18O) of NO3- and nitrite (NO2-) in the Pacific Antarctic Zone using depth profiles from late summer/fall of 2014. In the mixed layer, the δ15N and δ18O of NO3- + NO2- increase roughly equally, as expected for NO3- assimilation; however, the δ15N of NO3--only (measured after NO2- removal) increases more than does NO3--only δ18O. Differencing indicates that NO2- has an extremely low δ15N, often < -70‰ versus air. These observations are consistent with the expression of an equilibrium N isotope effect between NO3- and NO2-, likely due to enzymatic NO3--NO2- interconversion. Specifically, we propose reversibility of the nitrite oxidoreductase (NXR) enzyme of nitrite oxidizers that, having been entrained from the subsurface during late summer mixed layer deepening, are inhibited by light. Our interpretation suggests a role for NO3--NO2- interconversion where nitrifiers are transported into environments that discourage NO2- oxidation. This may apply to surface regions with upwelling, such as the summertime Antarctic. It may also apply to oxygen-deficient zones, where NXR-catalyzed interconversion may explain previously reported evidence of NO2- oxidation.

  13. Coupling Between and Among Ammonia Oxidizers and Nitrite Oxidizers in Grassland Mesocosms Submitted to Elevated CO2 and Nitrogen Supply.

    Science.gov (United States)

    Simonin, Marie; Le Roux, Xavier; Poly, Franck; Lerondelle, Catherine; Hungate, Bruce A; Nunan, Naoise; Niboyet, Audrey

    2015-10-01

    Many studies have assessed the responses of soil microbial functional groups to increases in atmospheric CO2 or N deposition alone and more rarely in combination. However, the effects of elevated CO2 and N on the (de)coupling between different microbial functional groups (e.g., different groups of nitrifiers) have been barely studied, despite potential consequences for ecosystem functioning. Here, we investigated the short-term combined effects of elevated CO2 and N supply on the abundances of the four main microbial groups involved in soil nitrification: ammonia-oxidizing archaea (AOA), ammonia-oxidizing bacteria (AOB), and nitrite-oxidizing bacteria (belonging to the genera Nitrobacter and Nitrospira) in grassland mesocosms. AOB and AOA abundances responded differently to the treatments: N addition increased AOB abundance, but did not alter AOA abundance. Nitrobacter and Nitrospira abundances also showed contrasted responses to the treatments: N addition increased Nitrobacter abundance, but decreased Nitrospira abundance. Our results support the idea of a niche differentiation between AOB and AOA, and between Nitrobacter and Nitrospira. AOB and Nitrobacter were both promoted at high N and C conditions (and low soil water content for Nitrobacter), while AOA and Nitrospira were favored at low N and C conditions (and high soil water content for Nitrospira). In addition, Nitrobacter abundance was positively correlated to AOB abundance and Nitrospira abundance to AOA abundance. Our results suggest that the couplings between ammonia and nitrite oxidizers are influenced by soil N availability. Multiple environmental changes may thus elicit rapid and contrasted responses between and among the soil ammonia and nitrite oxidizers due to their different ecological requirements.

  14. Evaluation of the laminin α5 expression in mice testicular parenchyma following an exposure to water contaminated with sodium nitrite

    Directory of Open Access Journals (Sweden)

    Sarah Amini

    2016-09-01

    Full Text Available Introduction: A reason causing male infertility is environmental pollutant. Nitrite is a common pollutant in rivers and water resources and also a concern because it can lead to the formation of N-nitrous compounds (NOC. Laminin is a glycoprotein which is as a major component of the extracellular matrix of testis. Some studies have demonstrated that chemicals and pollutants, including nicotine, can alter laminin expression. This study was designed to demonstrate the immunohistochemical changes in laminin expression in the testes of mice as a consequence of sodium nitrite administration. Material and Method: Twenty adult male mice weighing 25–30 g were classified into four groups: group I (control, group II (3 mg/l NaNO2, group III(10 mg/l NaNO2 and group IV received 50 mg/l NaNO2 in distilled water and control group only receiveddistilled water for 60 days. Immunohistochemical examinations of testicular specimens for laminin and quantitative eRT-PCR were performed. Results: The results of this study revealed alterations in group 4 compared with group I with increased laminin expression in elongated spermatids proved by increased staining reaction (p ≤ 0.038.The results were congruent with quantitative RT-PCR results by increase of 1.3 fold laminin mRNA in group IV in comparison with control group(p<0.05. Conclusion: It could be concluded that that increasing concentrations of sodium nitrite in drinking water can disturb the balance between the antioxidant and ROS in the microenvironment. Hence, oxidative stress induces the synthesis of laminin in the testes by reducing excess NO as well as increasing the NOXproduction.

  15. EFFECT OF NITRITE AND CITRIC ACID ON THE CHEMICAL COMPOSITION AND pH OF THE CANNED BEEF SAUSAGES

    Directory of Open Access Journals (Sweden)

    M.M.A. MAHA

    2015-01-01

    Full Text Available The effects of nitrite and citric acid as preservatives on the chemical composition and pH of the canned beef sausage were investigated after three months storage at room temperature (35±5ºc. Two experiments were conducted in this study, the first, was undertaken to determine the effect of nitrite as a preservative on the chemical composition and pH of the canned beef sausages retorted at 107.2°C (225ºF for 80 minutes, and at 115.5°C (240ºF for 40 minutes. The second experiment, which was based on the results of the first one, was conducted to determine the effects of the absence of nitrite on the canned beef sausage processed with meat treated by immersion in 1% citric acid before processing at (80 and 30ºc for one minute and drained, then the product retorted at 107.2°C for 80 minutes. The evaluation of percentages of the dry matter, ash, crude protein, fat and also pH were done monthly. The results in experiment 1 indicated that, percentages of the dry matter, ash and crude protein before and after canning of sausages were not significantly different (P>0.05. The fat (% was significantly different among treatments (P0.05 for the raw, cooked and canned sausages. Generally it was observed a decrease in moisture content (increases in dry matter content, ash%, crude protein fat (% and pH value with increasing of storage period. Citric acid had no clear effect on chemical properties and pH value.

  16. GIS-based methodologies for assessing nitrate, nitrite and ammonium distributions across a major UK basin, the Humber

    Directory of Open Access Journals (Sweden)

    H. Davies

    2004-01-01

    Full Text Available The distributions of nitrate, nitrite and ammonium at various monitoring sites across the Humber basin (area 24 000 km2 were examined within a Geographical Information System (GIS framework. This basin contains diverse characteristics, from areas of high population and industry to rural and arable regions. The Humber River is a major provider of and nutrient fluxes to the North Sea from the UK. Within the GIS analysis, the distributions of mean and mean flow weighted concentrations, flux and flux per unit area, were investigated. Empirical relationships between land characteristics and water quality for the whole catchment draining to each water quality monitoring site were established. Thirty-eight catchments were chosen for this analysis, with areas ranging from 46 km2 to 8225 km2. These catchments are distributed across the Humber, encompassing the different conditions across the basin, thus allowing relationships between water quality and catchment characteristics to be used to estimate the nitrogen concentrations and flux throughout the basin river network. The main water quality data source was the Land Ocean Interaction Study (LOIS dataset. The Environment Agency of England and Wales water quality datasets were used to infill areas of sparse LOIS monitoring network density within the Humber. The work shows the feasibility of estimating nitrate and, to a lesser extent, nitrite and ammonium concentrations and fluxes across the river network based on land characteristics, using a GIS methodology. The estimations work particularly well for the main river channels. However, there are local anomalies which are more difficult to predict. Maps showing concentration variations at 500 m intervals along the Humber basin river networks are presented; these are of particular value for environmental managers and socio-economists. Keywords: GIS, nitrate, nitrite, ammonium, catchment characteristics

  17. Spatial interaction of archaeal ammonia-oxidizers and nitrite-oxidizing bacteria in an unfertilized grassland soil

    Directory of Open Access Journals (Sweden)

    Barbara eStempfhuber

    2016-01-01

    Full Text Available Interrelated successive transformation steps of nitrification are performed by distinct microbial groups – the ammonia-oxidizers, comprising ammonia-oxidizing archaea (AOA and bacteria (AOB, and nitrite-oxidizers such as Nitrobacter and Nitrospira, which are the dominant genera in the investigated soils. Hence, not only their presence and activity in the investigated habitat is required for nitrification, but also their temporal and spatial interactions. To demonstrate the interdependence of both groups and to address factors promoting putative niche differentiation within each group, temporal and spatial changes in nitrifying organisms were monitored in an unfertilized grassland site over an entire vegetation period at the plot scale of 10 m². Nitrifying organisms were assessed by measuring the abundance of marker genes (amoA for AOA and AOB, nxrA for Nitrobacter, 16S rRNA gene for Nitrospira selected for the respective sub-processes. A positive correlation between numerically dominant AOA and Nitrospira, and their co-occurrence at the same spatial scale in August and October, suggests that the nitrification process is predominantly performed by these groups and is restricted to a limited timeframe. Amongst nitrite-oxidizers, niche differentiation was evident in observed seasonally varying patterns of co-occurrence and spatial separation. While their distributions were most likely driven by substrate concentrations, oxygen availability may also have played a role under substrate-limited conditions. Phylogenetic analysis revealed temporal shifts in Nitrospira community composition with an increasing relative abundance of OTU03 assigned to sublineage V from August onwards, indicating its important role in nitrite oxidation.

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

    Science.gov (United States)

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

    2015-02-01

    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%.

  19. A novel control method for nitritation: The domination of ammonia-oxidizing bacteria by high concentrations of inorganic carbon in an airlift-fluidized bed reactor.

    Science.gov (United States)

    Tokutomi, Takaaki; Shibayama, Chizu; Soda, Satoshi; Ike, Michihiko

    2010-07-01

    A novel nitritation method based on the addition of inorganic carbon (IC) was verified using an airlift-fluidized bed reactor packed with sponge cubes. A continuous-treatment experiment demonstrated that the type of nitrification-nitrite or nitrate accumulation-could be controlled by the addition of different alkalinity sources (NaHCO(3) or NaOH, respectively). The maximum rate of ammonia oxidation at 30 degrees C was 2.47kg-N/(m(3) d), with nitrate formation of less than 0.5% of the converted ammonia. Nitrite accumulation of over 90% was maintained stably over 250 days at 30 degrees C and was achieved even at 19 degrees C. Qualitative and quantitative shifts of nitrifying bacteria in the biofilm were monitored by real-time PCR and T-RFLP analysis. Ammonia-oxidizing bacteria (AOB) were dominant but nitrite-oxidizing bacteria (NOB) were eliminated in the reactor when NaHCO(3) was used as the alkalinity source. From the kinetic data, we inferred that high IC concentrations drive stable nitritation by promoting a higher growth rate for AOB than for NOB.

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

    Science.gov (United States)

    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

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

    Directory of Open Access Journals (Sweden)

    Alexandre Lamas

    2016-10-01

    Full Text Available 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.

  2. Novel oxidative coupling reactions of cisapride or metaclopramide with phenoxazines and their applications in the determination of nitrite at trace level in environmental samples

    Science.gov (United States)

    AL-Okab, Riyad Ahmed; Syed, Akheel Ahmed

    2007-11-01

    Phenoxazine (PNZ), 2-chlorophenoxazine (CPN) and 2-trifluoromethylphenoxazine (TPN) were used as new class of spectrophotometric reagents for the determination of nanoamounts of nitrite in presence of cisapride (CSP) and metaclopramide (MCP) as new electrophilic coupling reagents. The methods were based on the oxidation of CSP or MCP by nitrite in hydrochloric acid medium and coupling with PNZ, CPN or TPN to yield red color derivatives which were stable for about 3 h and having an absorbance maximum in the range 520-530 nm. Beer's law is obeyed for nitrite in the concentration range 0.08-0.80 and 0.13-1.60 μg ml -1 for phenoxazine-cisapride and phenoxazine-metaclopramide, respectively. The optimum reaction conditions and other important analytical parameters were established to enhance the sensitivity of these methods. Interference due to various non-target ions was also investigated. The methods were applied to the analysis of nitrite in environmental samples. The performance of proposed methods were evaluated by Student's t-test and variance ratio F-test indicated the significance of proposed methods over the reference spectrophotometric method (Association of Official Analytical Communities (AOAC) method for the determination of nitrite in water samples).

  3. Short-term hypoxic vasodilation in vivo is mediated by bioactive nitric oxide metabolites, rather than free nitric oxide derived from haemoglobin-mediated nitrite reduction.

    Science.gov (United States)

    Umbrello, Michele; Dyson, Alex; Pinto, Bernardo Bollen; Fernandez, Bernadette O; Simon, Verena; Feelisch, Martin; Singer, Mervyn

    2014-03-01

    Local increases in blood flow--'hypoxic vasodilation'--confer cellular protection in the face of reduced oxygen delivery. The physiological relevance of this response is well established, yet ongoing controversy surrounds its underlying mechanisms. We sought to confirm that early hypoxic vasodilation is a nitric oxide (NO)-mediated phenomenon and to study putative pathways for increased levels of NO, namely production from NO synthases, intravascular nitrite reduction, release from preformed stores and reduced deactivation by cytochrome c oxidase. Experiments were performed on spontaneously breathing, anaesthetized, male Wistar rats undergoing short-term systemic hypoxaemia, who received pharmacological inhibitors and activators of the various NO pathways. Arterial blood pressure, cardiac output, tissue oxygen tension and the circulating pool of NO metabolites (oxidation, nitrosation and nitrosylation products) were measured in plasma and erythrocytes. Hypoxaemia caused a rapid and sustained vasodilation, which was only partially reversed by non-selective NO synthase inhibition. This was associated with significantly lower plasma nitrite, and marginally elevated nitrate levels, suggestive of nitrite bioinactivation. Administration of sodium nitrite had little effect in normoxia, but produced significant vasodilation and increased nitrosylation during hypoxaemia that could not be reversed by NO scavenging. Methodological issues prevented assessment of the contribution, if any, of reduced deactivation of NO by cytochrome c oxidase. In conclusion, acute hypoxic vasodilation is an adaptive NO-mediated response conferred through bioactive metabolites rather than free NO from haemoglobin-mediated reduction of nitrite.

  4. Stability of α-tocotrienol and α-tocopherol in salami-type sausages and curing brine depending on nitrite and pH.

    Science.gov (United States)

    Gerling, Eva-Maria; Ternes, Waldemar

    2014-12-01

    We studied the stability of the valuable vitamer nutrients α-tocotrienol and α-tocopherol and options for their protection in salami-type sausages (blended with α-tocotrienol-rich barley oil) and curing brine. Four different sausage formulations were produced containing nitrite curing salt; nitrite curing salt and ascorbic acid (300mg/kg); nitrite curing salt and carnosic acid (45mg/kg); or sodium chloride. Initial vitamer contents (100mg/kg) did not decrease significantly during ripening and decreased only slightly during storage. Ascorbic acid and carnosic acid were found to be effective in preserving the vitamers in fresh sausages. Freeze-drying of sausages resulted in a significant loss of vitamers (97%), particularly after 14-day storage at room temperature, even in the presence of shielding gases. The vitamer content in the curing brine decreased with decreasing pH in the presence of nitrite. A nitrite concentration of 136mg/L at pH4 resulted in significant loss (90%) of the vitamers. Sufficient stability of the vitamers in salami-type sausage and curing brine can be achieved by processing, formulation, and storage conditions.

  5. Achieving nitrogen removal via nitrite pathway from urban landfill leachate using the synergetic inhibition of free ammonia and free nitrous acid on nitrifying bacteria activity.

    Science.gov (United States)

    Sun, H W; Bai, Y; Peng, Y Z; Xie, H G; Shi, X N

    2013-01-01

    In this study, a biological system consisting of an up-flow anaerobic sludge blanket (UASB) and anoxic-oxic (A/O) reactor was established for the advanced treatment of high ammonium urban landfill leachate. The inhibitory effect of free ammonia (FA) and free nitrous acid (FNA) on the nitrifying bacterial activity was used to achieve stable nitritation in the A/O reactor. The results demonstrated that the biological system achieved chemical oxygen demand (COD), total nitrogen (TN) and NH(4)(+)-N removal efficiencies of 95.3, 84.6 and 99.2%, respectively at a low carbon-to-nitrogen ratio of 3:1. Simultaneous denitritation and methanogenesis in the UASB could improve the removal of COD and TN. Nitritation with above 90% nitrite accumulation was successfully achieved in the A/O reactor by synergetic inhibition of FA and FNA on the activity of nitrite oxidizing bacteria (NOB). Fluorescence in situ hybridization (FISH) analysis showed that ammonia oxidizing bacteria (AOB) was dominant and was considered to be responsible for the satisfactory nitritation performance.

  6. The effects of endothelial nitric oxide synthase tagSNPs on nitrite levels and risk of hypertension and obesity in children and adolescents.

    Science.gov (United States)

    de Miranda, J A; Lacchini, R; Belo, V A; Lanna, C M M; Sertorio, J T; Luizon, M R; Tanus-Santos, J E

    2015-02-01

    Obesity and the nitric oxide synthase 3 (NOS3) gene polymorphisms are associated with nitrite levels and hypertension. However, no study has tested the hypothesis that NOS3 tagSNPs rs3918226, rs3918188, rs743506 and rs7830 affect nitrite levels and are associated with hypertension in childhood obesity. We investigated the association of these NOS3 tagSNPs and the haplotypes formed by them with hypertension and with nitrite levels in children and adolescents with obesity and with obesity plus hypertension. We studied 355 subjects: 174 healthy (controls), 109 normotensive obese, and 72 obese children and adolescents with obesity plus hypertension. Genotypes were determined by Taqman allele discrimination assay and real-time PCR. We compared the distribution of NOS3 tagSNP genotypes, alleles and haplotypes in the three groups of subjects. Nitrite levels were determined by ozone-based chemiluminescence. Nitrite levels were affected by the rs3918226 polymorphism (Phypertension in children and adolescents. Our findings show that the NOS3 tagSNP rs3918226 is associated with NO production in children and adolescents, and suggest that this polymorphism may have an impact on cardiovascular health. Further studies are needed to better clarify the effects of this polymorphism on cardiovascular risk.

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

    Science.gov (United States)

    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%.

  8. Acute effect of nitric oxide supplement on blood nitrate/nitrite and hemodynamic variables in resistance trained men.

    Science.gov (United States)

    Bloomer, Richard J; Williams, Sara A; Canale, Robert E; Farney, Tyler M; Kabir, Mohammad M

    2010-10-01

    Nitric oxide dietary supplements are extremely popular within the sport and bodybuilding community. Most products contain l-arginine, for which there is no direct evidence that oral L-arginine increases circulating nitric oxide or blood flow. A new molecule (2-[nitrooxy]thyl 2-amino-3-methylbutanoate) is being marketed as a sport supplement for purposes of delivering "real nitric oxide" to the circulation. In the present study, we measured the acute effects of this supplement on blood nitrate/nitrite and hemodynamic variables. Ten resistance trained men (26 ± 4 years old; 8 ± 6 years of resistance exercise training) reported to the laboratory in random order after a 10-hour overnight fast on 2 occasions separated by 1 week and were provided the supplement (2-[nitrooxy]ethyl 2-amino-3-methylbutanoate) or placebo. Heart rate and blood pressure were recorded, and venous blood samples were collected before and at 5, 15, 30, and 60 minutes after complete breakdown of the supplement (5 minutes post intake) or placebo. Blood samples were assayed for plasma nitrate/nitrite. No interaction (p = 0.99), condition (p = 0.18), or time (p = 0.98) effects were noted for plasma nitrate/nitrite, with values remaining nearly identical across time for placebo (∼27 μmol·L(-1)) and increasing a maximum of ∼6.7% (from 32.9 to 35.1 μmol·L(-1)) at the 15-minute collection period for the supplement. In regards to hemodynamic variables, no interaction, condition, or time effects were noted for heart rate, systolic, or diastolic blood pressure (p > 0.05), with values near identical between conditions and virtually unchanged across time. These findings indicate that 2-(nitrooxy)ethyl 2-amino-3-methylbutanoate has a small effect on increasing circulating nitrate/nitrite and does not cause any change in hemodynamic variables within the 1 hour postingestion period in a sample of resistance trained men.

  9. Production and mitigation of N2O in sequentially membrane-aerated redox-stratified nitritation/anammox biofilms

    DEFF Research Database (Denmark)

    Smets, Barth F.; Pellicer i Nàcher, Carles; Thamdrup, Bo;

    Combining partial nitritation with anaerobic ammonium oxidation maybe a cost- and energy-efficient alternative to remove reduced nitrogen from nitrogen rich waste streams. However, increased N2O emissions (upto several % of the incoming N flux) have been observed for reactors performing partial......) conditions. Although anaerobic ammonium oxidizing bacteria are not known to metabolize N2O, we speculate that the existence of oxygen free zone would permit complete expression ofa denitrification pathway by heterotrophic bacteria- and hence remove any N2O which is transiently produced in the inner (aerobic...

  10. Thermal fluids for CSP systems: Alkaline nitrates/nitrites thermodynamics modelling method

    Science.gov (United States)

    Tizzoni, A. C.; Sau, S.; Corsaro, N.; Giaconia, A.; D'Ottavi, C.; Licoccia, S.

    2016-05-01

    Molten salt (MS) mixtures are used for the transport (HTF-heat transfer fluid) and storage of heat (HSM-heat storage material) in Concentration Solar Plants (CSP). In general, alkaline and earth-alkaline nitrate/nitrite mixtures are employed. Along with its upper stability temperature, the melting point (liquidus point) of a MS mixture is one of the main parameters which defines its usefulness as a HTF and HSM medium. As a result, we would like to develop a predictive model which will allow us to forecast freezing points for different MS mixture compositions; thus circumventing the need to determine experimentally the phase diagram for each MS mixture. To model ternary/quaternary phase diagram, parameters for the binary subsystems are to be determined, which is the purpose of the concerned work. In a binary system with components A and B, in phase equilibrium conditions (e.g. liquid and solid) the chemical potentials (partial molar Gibbs energy) for each component in each phase are equal. For an ideal solution it is possible to calculate the mixing (A+B) Gibbs energy:ΔG = ΔH - TΔS = RT(xAlnxA + xBlnxB) In case of non-ideal solid/liquid mixtures, such as the nitrates/nitrites compositions investigated in this work, the actual value will differ from the ideal one by an amount defined as the "mixing" (mix) Gibbs free energy. If the resulting mixtures is assumed, as indicated in the previous literature, to follow a "regular solution" model, where all the non-ideality is considered included in the enthalpy of mixing value and considering, for instance, the A component:Δ G ≡0 =(Δ HA-T Δ SA)+(ΔH¯ m i x AL-T ΔS¯ m i x AL)-(ΔH¯ m i x AS-T ΔS¯ m i x AS)where the molar partial amounts can be calculated from the total value by the Gibbs Duhem equation: (ΔH¯m i x AL=ΔHm i x-XB Ld/Δ Hm i x d XB L ) L;(ΔH¯m i x AS=ΔHm i x-XB Sd/Δ Hm i x d XB S ) S and, in general, it is possible to express the mixing enthalpy for solids and liquids as a function of the mol

  11. SNOW2002: NOx Production From Nitrate-In-Ice Photolysis at Two pHs and Comparison with NOx Levels From Nitrite-In-Ice Photolysis

    Science.gov (United States)

    Peterson, M.; Dibb, J.

    2002-12-01

    We conducted experiments using artificial snow, synthetic air, and sunlight during January, 2002 (the SNOW2002 study) in order to test the influence of neutral and basic pH on the amount of NO, NO2, and NOx emitted from artificial snow during nitrate photolysis. We also conducted the first tests demonstrating that illumination of consolidated, sub-millimeter diameter ice particles (e.g., artificial snow) doped with nitrite produces NOx, confirming that nitrite photolysis occurs in ice and snow. Innovations in NOx instrument design were also implemented in order to estimate gaseous HONO levels using UV lamp photolysis. Nitrate was introduced into solution as sodium nitrate, pH was controlled using sodium hydroxide. Artificial snow particles were formed by spraying tiny water droplets down into a tall (3 meter) column chilled by a pool of liquid nitrogen at the column base. Although this method of creating artificial snow results in snow that is certainly different than natural snow, the tiny ice particles formed are powdery and sinter quickly. This artificial snow is relatively easy to make and is well suited for determining whether photolysis of nitrate or nitrite is occurring, and whether changes occur at various pH levels. The amounts of NO and NO2 produced by nitrate ion photolysis in aqueous solution depends on pH such that NO production is greatly enhanced in basic solutions. Our preliminary results indicate that the pH of the solutions used to make artificial snow does not effect the levels or partitioning of NOx produced from nitrate-in-ice photolysis. This result suggests that aqueous photochemical analogs of nitrate photolysis may not apply to nitrate-in-ice photochemistry and that more experiments are needed in order to understand nitrate-in-ice photochemistry. Experiments exploring nitrite-in-ice photolysis demonstrate that there is one to two orders of magnitude more NOx produced by nitrite photolysis than by nitrate photolysis at equivalent conditions

  12. Nitrite detection in meat products samples by square-wave voltammetry at a new single walled carbon naonotubes--myoglobin modified electrode.

    Science.gov (United States)

    Turdean, Graziella L; Szabo, Gabriella

    2015-07-15

    A new modified electrode was realized in a simple way, consisting by the immobilization of a myoglobin (My) - single walled carbon nanotubes (SWCNT) mixture on the surface of a graphite electrode with a Nafion film. The cyclic voltammetry investigations realized with the obtained electrode (G/My-SWCNT/Nafion) showed a voltammetric signal due to a one-step redox reaction of the surface-confined myoglobin, in a deaerated 0.1 M phosphate buffer, pH 7. Also, the G/My-SWCNT/Nafion modified electrode demonstrated a great potential for the analytical determination of nitrite ions by square-wave voltammetry and an alternative for the already existing methods. The use of the sensor for the detection of nitrite ions in samples of meat products leads to comparable results with those obtained with the standard Griess spectrophotometric assay (ISO 2918/1975), proving the suitability of using immobilized myoglobin as electrocatalyst in the nitrite reduction process.

  13. A novel and simple electrochemical sensor for electrocatalytic reduction of nitrite and oxidation of phenylhydrazine based on poly (o-anisidine) film using ionic liquid carbon paste electrode

    Energy Technology Data Exchange (ETDEWEB)

    Ojani, Reza, E-mail: fer-o@umz.ac.ir [Electroanalytical Chemistry Research Laboratory, Faculty of Chemistry, University of Mazandaran, Babolsar (Iran, Islamic Republic of); Raoof, Jahan-Bakhsh; Zamani, Saeed [Electroanalytical Chemistry Research Laboratory, Faculty of Chemistry, University of Mazandaran, Babolsar (Iran, Islamic Republic of)

    2013-04-15

    In this study, nitrite electroreduction and phenylhydrazine electrooxidation were investigated on poly(o-anisidine) formed by cyclic voltammetry at the surface of ionic liquid carbon paste electrode. The films were characterized by cyclic voltammetry and scanning electron microscopy (SEM) and were contrasted with poly(o-anisidine) prepared under identical conditions in the absence of ionic liquid in carbon paste electrode. This carbon paste modified electrode exhibits a good electrocatalytic capability (via an EC’ mechanism) for both electrooxidation and electroreduction of some important molecules. The obtained results showed that the catalytic oxidation peak currents of phenylhydrazine and catalytic reduction peak currents of nitrite at the surface of this simple (unfunctionalized) polymeric electrode were linearly dependent on their concentrations. Electrode was successfully applied for determination of nitrite and phenylhydrazine in real samples.

  14. The Impact of Environmental Factors on the Amount of Nitrates and Nitrites in Different Types of Soils and Ways of Their Utilization

    Science.gov (United States)

    Bachvarova, Darina; Rafi, Renay; Doichinov, Aleksandar

    2017-03-01

    Despite the last decade considerable advances in the study of nitrate and nitrite pollution of soil, there are still some gaps in research related to neglecting or ignoring the role of soil in the food chain and its effects on upper trophic units. The article presents the results of a study on the impact of air and soil humidity and temperature, as well as soil type and utilization on the amount of nitrates and nitrites in the soil solution at the end of vegetation period. It was proved that statistically significant impact on the amounts of residual nitrate and nitrite ions was caused by the temperature and moisture of soil, its type, and the specific properties of the crops grown.

  15. Characterization of a new marine nitrite oxidizing bacterium, Nitrospina watsonii sp. nov., a member of the newly proposed phylum "Nitrospinae".

    Science.gov (United States)

    Spieck, Eva; Keuter, Sabine; Wenzel, Thilo; Bock, Eberhard; Ludwig, Wolfgang

    2014-05-01

    Nitrite oxidizing bacteria are an integral part of the nitrogen cycle in marine waters, but the knowledge about their diversity is limited. Recently, a high abundance of Nitrospina-like 16S rRNA gene sequences has been detected in oceanic habitats with low oxygen content by molecular methods. Here, we describe a new strain of Nitrospina, which was sampled in 100m depth from the Black Sea. It coexisted with a not-yet cultivated chemoorganotrophic gammaproteobacterium and could be purified by classical isolation methods including Percoll density gradient centrifugation. The new Nitrospina-like bacterium grew lithoautotrophically at 28°C in diluted seawater supplemented with inorganic salts and nitrite. Gram-negative rods were characterized morphologically, physiologically and partly biochemically. The 16S rRNA gene of the new strain of Nitrospina is 97.9% similar to the described species N. gracilis and DNA/DNA hybridization experiments revealed a relatedness of 30.0%. The data from both Nitrospina species and environmental clones were used for an extensive 16S rRNA based phylogenetic study applying high quality filtering. Treeing analyses confirm the newly defined phylum status for "Nitrospinae" [18]. The results of phylogenetic and genotypic analyses support the proposal of a novel species Nitrospina watsonii sp. nov. (type strain 347(T), LMG 27401(T), NCIMB 14887(T)).

  16. Antilisterial effects of antibacterial formulations containing essential oils, nisin, nitrite and organic acid salts in a sausage model.

    Science.gov (United States)

    Ghabraie, Mina; Vu, Khanh Dang; Huq, Tanzina; Khan, Avik; Lacroix, Monique

    2016-06-01

    This study was conducted to evaluate the effects of sixteen antibacterial formulations against Listeria monocytogenes in a sausage model using a standard experimental design with 4 independent factors at 2 levels (2(4)). Four independent factors consisted of nisin (12.5-25 ppm), nitrite (100-200 ppm) and organic acid salts (1.55-3.1 %) and the mixture of Chinese cinnamon and Cinnamon bark Essential Oils (EOs) (0.025-0.05 %). Based on the analysis, utilization of low (0.025 %) or high concentration (0.05 %) of EOs in combination with low concentration of nitrite (100 ppm), organic acid salts (1.55 %), and nisin (12.5 ppm) could reduce respectively 1.5 or 2.6 log CFU/g of L. monocytogenes in sausage at day 7 of storage as compared to the control. A predictive equation was created to predict the growth of L. monocytogenes in sausage. The sensory evaluation was then performed on selected optimized formulations in cooked meat (both pork and beef sausages) with a trained jury consisting of 35 individuals, demonstrated the selected antimicrobial formulations were organoleptically acceptable. The results revealed an important role of hurdle technology to control L. monocytogenes in meat product.

  17. Preliminary safe-handling experiments on a mixture of cesium nickel ferrocyanide and equimolar sodium nitrate/nitrite

    Energy Technology Data Exchange (ETDEWEB)

    Scheele, R.D. (Pacific Northwest Lab., Richland, WA (United States)); Cady, H.H. (Los Alamos National Lab., NM (United States))

    1992-01-01

    As part of the Hanford Site's evaluation of the potential hazards associated with the storage of ferrocyanide wastes generated when ferrocyanide was used to scavenge radiocesium from waste supernates in the 1950s, the Pacific Northwest Laboratory (PNL) subcontracted with Los Alamos National Laboratory (LANL) to perform a series of sensitivity tests. These test supplement PNL's thermal sensitivity testing results on the reactivity of cesium nickel ferrocyanide (Cs{sub 2}NiFe(CN){sub 6}) and nitrates and nitrites (Burger and Schelle 1991). LANL used a selected set of their standard tests to determine the sensitivity of a mixture of Cs{sub 2}NiFe(CN){sub 6} (FECN-1) and equimolar sodium nitrate and nitrite oxidant to nonthermal and thermal stimuli. The stoichiometric ratio of oxidant to Cs{sub 2}NiFe(CN){sub 6} in the tested mixture FECN-1 was 1.1:1. The appendix presents the results of the LANL testing of the sensitivity of FECN-1 to initiation by mechanical impact, spark, friction, and various thermal conditions. In addition to the sensitivity testing, LANL used an Accelerating Rate Calorimeter (ARC) to estimate the behavior of large batches of the mixture.

  18. Preliminary safe-handling experiments on a mixture of cesium nickel ferrocyanide and equimolar sodium nitrate/nitrite

    Energy Technology Data Exchange (ETDEWEB)

    Scheele, R.D. [Pacific Northwest Lab., Richland, WA (United States); Cady, H.H. [Los Alamos National Lab., NM (United States)

    1992-01-01

    As part of the Hanford Site`s evaluation of the potential hazards associated with the storage of ferrocyanide wastes generated when ferrocyanide was used to scavenge radiocesium from waste supernates in the 1950s, the Pacific Northwest Laboratory (PNL) subcontracted with Los Alamos National Laboratory (LANL) to perform a series of sensitivity tests. These test supplement PNL`s thermal sensitivity testing results on the reactivity of cesium nickel ferrocyanide (Cs{sub 2}NiFe(CN){sub 6}) and nitrates and nitrites (Burger and Schelle 1991). LANL used a selected set of their standard tests to determine the sensitivity of a mixture of Cs{sub 2}NiFe(CN){sub 6} (FECN-1) and equimolar sodium nitrate and nitrite oxidant to nonthermal and thermal stimuli. The stoichiometric ratio of oxidant to Cs{sub 2}NiFe(CN){sub 6} in the tested mixture FECN-1 was 1.1:1. The appendix presents the results of the LANL testing of the sensitivity of FECN-1 to initiation by mechanical impact, spark, friction, and various thermal conditions. In addition to the sensitivity testing, LANL used an Accelerating Rate Calorimeter (ARC) to estimate the behavior of large batches of the mixture.

  19. Structure and composition of biofilm communities in a moving bed biofilm reactor for nitritation-anammox at low temperatures.

    Science.gov (United States)

    Persson, Frank; Sultana, Razia; Suarez, Marco; Hermansson, Malte; Plaza, Elzbieta; Wilén, Britt-Marie

    2014-02-01

    It is a challenge to apply anaerobic ammonium oxidation (anammox) for nitrogen removal from wastewater at low temperatures. Maintenance of anammox- and aerobic ammonia oxidizing bacteria (AOB) and suppression of nitrite oxidizing bacteria (NOB) are key issues. In this work, a nitritation-anammox moving bed biofilm pilot reactor was operated at 19-10°C for 300 d. Nitrogen removal was decreasing, but stable, at 19-13°C. At 10°C removal became unstable. Quantitative PCR, fluorescence in situ hybridization and gene sequencing showed that no major microbial community changes were observed with decreased temperature. Anammox bacteria dominated the biofilm (0.9-1.2 × 10(14) 16S rRNA copies m(-2)). Most anammox bacteria were similar to Brocadia sp. 40, but another smaller Brocadia population was present near the biofilm-water interface, where also the AOB community (Nitrosomonas) was concentrated in thin layers (1.8-5.3 × 10(12) amoA copies m(-2)). NOB (Nitrobacter, Nitrospira) were always present at low concentrations (<1.3 × 10(11) 16S rRNA copies m(-2)).

  20. Direct electrochemistry of cytochrome c immobilized on titanium nitride/multi-walled carbon nanotube composite for amperometric nitrite biosensor.

    Science.gov (United States)

    Haldorai, Yuvaraj; Hwang, Seung-Kyu; Gopalan, Anantha-Iyengar; Huh, Yun Suk; Han, Young-Kyu; Voit, Walter; Sai-Anand, Gopalan; Lee, Kwang-Pill

    2016-05-15

    In this report, titanium nitride (TiN) nanoparticles decorated multi-walled carbon nanotube (MWCNTs) nanocomposite is fabricated via a two-step process. These two steps involve the decoration of titanium dioxide nanoparticles onto the MWCNTs surface and a subsequent thermal nitridation. Transmission electron microscopy shows that TiN nanoparticles with a mean diameter of ≤ 20 nm are homogeneously dispersed onto the MWCNTs surface. Direct electrochemistry and electrocatalysis of cytochrome c immobilized on the MWCNTs-TiN composite modified on a glassy carbon electrode for nitrite sensing are investigated. Under optimum conditions, the current response is linear to its concentration from 1 µM to 2000 µM with a sensitivity of 121.5 µA µM(-1)cm(-2) and a low detection limit of 0.0014 µM. The proposed electrode shows good reproducibility and long-term stability. The applicability of the as-prepared biosensor is validated by the successful detection of nitrite in tap and sea water samples.

  1. Short communication: Use of a mixture of sodium nitrite, sodium benzoate, and potassium sorbate in aerobically challenged silages.

    Science.gov (United States)

    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.

  2. Magnetic hydroxyapatite nanoparticles: an efficient adsorbent for the separation and removal of nitrate and nitrite ions from environmental samples.

    Science.gov (United States)

    Ghasemi, Ensieh; Sillanpää, Mika

    2015-01-01

    A novel type of magnetic nanosorbent, hydroxyapatite-coated Fe2O3 nanoparticles was synthesized and used for the adsorption and removal of nitrite and nitrate ions from environmental samples. The properties of synthesized magnetic nanoparticles were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray powder diffraction. After the adsorption process, the separation of γ-Fe2O3@hydroxyapatite nanoparticles from the aqueous solution was simply achieved by applying an external magnetic field. The effects of different variables on the adsorption efficiency were studied simultaneously using an experimental design. The variables of interest were amount of magnetic hydroxyapatite nanoparticles, sample volume, pH, stirring rate, adsorption time, and temperature. The experimental parameters were optimized using a Box-Behnken design and response surface methodology after a Plackett-Burman screening design. Under the optimum conditions, the adsorption efficiencies of magnetic hydroxyapatite nanoparticles adsorbents toward NO3(-) and NO2(-) ions (100 mg/L) were in the range of 93-101%. The results revealed that the magnetic hydroxyapatite nanoparticles adsorbent could be used as a simple, efficient, and cost-effective material for the removal of nitrate and nitrite ions from environmental water and soil samples.

  3. Nitrite to nitric oxide interconversion by heme FeII complex assisted by [CuI(tmpa)]+

    KAUST Repository

    Turias, Francesc

    2015-09-09

    The present computational study complements the recent experimental efforts by Karlin and coworkers to describe the interconversion of nitrite to nitric oxide by means of an iron porphyrin complex together with a Cu chemical system, i.e., the iron(II) complex (F8TPP)FeII [F8TPP = tetrakis(2,6-difluorophenyl)porphyrinate(2−)] and a preformed copper(II)–nitrito complex [(tmpa)CuII(NO2)][B(C6F5)4] [tmpa = tris(2-pyridylmethyl)amine], being the latter an oxidized species of [(tmpa)CuI(MeCN)]+. By DFT calculations, we unravel how the reduction of nitrite to nitric oxide takes place through a μ-oxo heme-FeIII–O–CuII complex, following a mimetic path as in the cytochrome c oxidase. Mayer bond order (MBO) and energy decomposition analyses are used to analyze the bonding strength of such nitro derivatives to either copper or iron. © 2015 Springer Science+Business Media New York

  4. Corrosion Inhibiting Mechanism of Nitrite Ion on the Passivation of Carbon Steel and Ductile Cast Iron for Nuclear Power Plants

    Directory of Open Access Journals (Sweden)

    K. T. Kim

    2015-01-01

    Full Text Available While NaNO2 addition can greatly inhibit the corrosion of carbon steel and ductile cast iron, in order to improve the similar corrosion resistance, ca. 100 times more NaNO2 addition is needed for ductile cast iron compared to carbon steel. A corrosion and inhibition mechanism is proposed whereby NO2- ion is added to oxidize. The NO2- ion can be reduced to nitrogen compounds and these compounds may be absorbed on the surface of graphite. Therefore, since nitrite ion needs to oxidize the surface of matrix and needs to passivate the galvanic corroded area and since it is absorbed on the surface of graphite, a greater amount of corrosion inhibitor needs to be added to ductile cast iron compared to carbon steel. The passive film of carbon steel and ductile cast iron, formed by NaNO2 addition showed N-type semiconductive properties and its resistance, is increased; the passive current density is thus decreased and the corrosion rate is then lowered. In addition, the film is mainly composed of iron oxide due to the oxidation by NO2- ion; however, regardless of the alloys, nitrogen compounds (not nitrite were detected at the outermost surface but were not incorporated in the inner oxide.

  5. A sub-minute CZE method to determine nitrate and nitrite in meat products: An alternative for routine analysis.

    Science.gov (United States)

    Della Betta, Fabiana; Pereira, Lais Morilla; Siqueira, Mariana Araújo; Valese, Andressa Camargo; Daguer, Heitor; Fett, Roseane; Vitali, Luciano; Costa, Ana Carolina Oliveira

    2016-09-01

    A sub-minute capillary zone electrophoresis (CZE) method was optimized and a simple sample preparation procedure based on the extraction of the analytes with water and sodium tetraborate was developed for the simultaneous determination of nitrate and nitrite levels in meat products. The background electrolyte (BGE) was composed of 20mmolL(-1) perchloric acid and 65mmolL(-1) β-alanine at pH3.83. Thiocyanate was used as the internal standard. The proposed method was validated and the uncertainty estimated according to Eurachem guidelines. The run time was only 30s, allowing analyzing more than 25samples/h, the good analytical performance confirms the suitability of the method for the analysis of meat products. One sample presented residual nitrite levels above the limit established by MERCOSUL legislation (150mgkg(-1)). The use of a fast method in association with a simple sample preparation step means that this procedure represents a possible alternative to fulfill the demand for high throughput in routine laboratory analysis.

  6. Sodium nitrite induces acute central nervous system toxicity in guinea pigs exposed to systemic cell-free hemoglobin.

    Science.gov (United States)

    Buehler, Paul W; Butt, Omer I; D'Agnillo, Felice

    2011-06-10

    Systemic cell-free hemoglobin (Hb) released via hemolysis disrupts vascular homeostasis, in part, through the scavenging of nitric oxide (NO). Sodium nitrite (NaNO(2)) therapy can attenuate the hypertensive effects of Hb. However, the chemical reactivity of NaNO(2) with Hb may enhance heme- or iron-mediated toxicities. Here, we investigate the effect of NaNO(2) on the central nervous system (CNS) in guinea pigs exposed to systemic cell-free Hb. Intravascular infusion of NaNO(2), at doses sufficient to alleviate Hb-mediated blood pressure changes, reduced the expression of occludin, but not zona occludens-1 (ZO-1) or claudin-5, in cerebral tight junctions 4h after Hb infusion. This was accompanied by increased perivascular heme oxygenase-1 expression, neuronal iron deposition, increased astrocyte and microglial activation, and reduced expression of neuron-specific nuclear protein (NeuN). These CNS changes were not observed in animals treated with Hb or NaNO(2) alone. Taken together, these findings suggest that the use of nitrite salts to treat systemic Hb exposure may promote acute CNS toxicity.

  7. The role of inoculum and reactor configuration for microbial community composition and dynamics in mainstream partial nitritation anammox reactors.

    Science.gov (United States)

    Agrawal, Shelesh; Karst, Søren M; Gilbert, Eva M; Horn, Harald; Nielsen, Per H; Lackner, Susanne

    2017-03-10

    Implementation of partial nitritation anammox (PNA) in the mainstream (municipal wastewater treatment) is still under investigation. Microbial community structure and reactor type can influence the performance of PNA reactor; yet, little is known about the role of the community composition of the inoculum and the reactor configuration under mainstream conditions. Therefore, this study investigated the community structure of inocula of different origin and their consecutive community dynamics in four different lab-scale PNA reactors with 16S rRNA gene amplicon sequencing. These reactors were operated for almost 1 year and subjected to realistic seasonal temperature fluctuations as in moderate climate regions, that is, from 20°C in summer to 10°C in winter. The sequencing analysis revealed that the bacterial community in the reactors comprised: (1) a nitrifying community (consisting of anaerobic ammonium-oxidizing bacteria (AnAOB), ammonia-oxidizing bacteria (AOB), and nitrite-oxidizing bacteria (NOB)); (2) different heterotrophic denitrifying bacteria and other putative heterotrophic bacteria (HB). The nitrifying community was the same in all four reactors at the genus level, although the biomasses were of different origin. Community dynamics revealed a stable community in the moving bed biofilm reactors (MBBR) in contrast to the sequencing batch reactors (SBR) at the genus level. Moreover, the reactor design seemed to influence the community dynamics, and reactor operation significantly influenced the overall community composition. The MBBR seems to be the reactor type of choice for mainstream wastewater treatment.

  8. Three-dimensional stratification of bacterial biofilm populations in a moving bed biofilm reactor for nitritation-anammox.

    Science.gov (United States)

    Almstrand, Robert; Persson, Frank; Daims, Holger; Ekenberg, Maria; Christensson, Magnus; Wilén, Britt-Marie; Sörensson, Fred; Hermansson, Malte

    2014-01-29

    Moving bed biofilm reactors (MBBRs) are increasingly used for nitrogen removal with nitritation-anaerobic ammonium oxidation (anammox) processes in wastewater treatment. Carriers provide protected surfaces where ammonia oxidizing bacteria (AOB) and anammox bacteria form complex biofilms. However, the knowledge about the organization of microbial communities in MBBR biofilms is sparse. We used new cryosectioning and imaging methods for fluorescence in situ hybridization (FISH) to study the structure of biofilms retrieved from carriers in a nitritation-anammox MBBR. The dimensions of the carrier compartments and the biofilm cryosections after FISH showed good correlation, indicating little disturbance of biofilm samples by the treatment. FISH showed that Nitrosomonas europaea/eutropha-related cells dominated the AOB and Candidatus Brocadia fulgida-related cells dominated the anammox guild. New carriers were initially colonized by AOB, followed by anammox bacteria proliferating in the deeper biofilm layers, probably in anaerobic microhabitats created by AOB activity. Mature biofilms showed a pronounced three-dimensional stratification where AOB dominated closer to the biofilm-water interface, whereas anammox were dominant deeper into the carrier space and towards the walls. Our results suggest that current mathematical models may be oversimplifying these three-dimensional systems and unless the multidimensionality of these systems is considered, models may result in suboptimal design of MBBR carriers.

  9. Three-Dimensional Stratification of Bacterial Biofilm Populations in a Moving Bed Biofilm Reactor for Nitritation-Anammox

    Directory of Open Access Journals (Sweden)

    Robert Almstrand

    2014-01-01

    Full Text Available Moving bed biofilm reactors (MBBRs are increasingly used for nitrogen removal with nitritation-anaerobic ammonium oxidation (anammox processes in wastewater treatment. Carriers provide protected surfaces where ammonia oxidizing bacteria (AOB and anammox bacteria form complex biofilms. However, the knowledge about the organization of microbial communities in MBBR biofilms is sparse. We used new cryosectioning and imaging methods for fluorescence in situ hybridization (FISH to study the structure of biofilms retrieved from carriers in a nitritation-anammox MBBR. The dimensions of the carrier compartments and the biofilm cryosections after FISH showed good correlation, indicating little disturbance of biofilm samples by the treatment. FISH showed that Nitrosomonas europaea/eutropha-related cells dominated the AOB and Candidatus Brocadia fulgida-related cells dominated the anammox guild. New carriers were initially colonized by AOB, followed by anammox bacteria proliferating in the deeper biofilm layers, probably in anaerobic microhabitats created by AOB activity. Mature biofilms showed a pronounced three-dimensional stratification where AOB dominated closer to the biofilm-water interface, whereas anammox were dominant deeper into the carrier space and towards the walls. Our results suggest that current mathematical models may be oversimplifying these three-dimensional systems and unless the multidimensionality of these systems is considered, models may result in suboptimal design of MBBR carriers.

  10. Kinetics of nitrite reduction by zinc metal: influence of metal shape on the determination of kinetic parameters.

    Science.gov (United States)

    Limousy, L; Dutournie, P; Hadjiev, D

    2010-07-01

    Heterogeneous chemical reactions are complicated, especially in the case of competitive reactions. The aim of this study was to investigate the elimination of nitrite (NO2(-)) by applying a metallic reduction using zero-valent zinc (Zn0). The effect of pH, stirring, and metal shape (powder and chips) on the rate and products of nitrite reduction were studied in a batch-stirred reactor. The obtained data have been used to optimize the conditions for metallic reduction of NO2(-) and for kinetic parameters identification. It was found that the dissolution of zinc involves a pseudo-first-order reaction independent of the shape of the metal. Further, the influence of operating conditions on nitrogen (N2) and ammonium (NH4(+)) formation has been determined. It was found that a decrease in pH and in the Zn0 content enhances NH4(+) production. If kinetic parameters can be approximated easily for constant surface area, it was demonstrated that surface evolution had to be integrated for metal powder. Finally, a numerical simulation has been used to determine the kinetic parameters for NO2(-) reduction with zinc powder.

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

    Science.gov (United States)

    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 ind