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1
Fu, Ruiling. "Using High-Field NMR to Identify the Bioactive Compounds in Extracts of Black Raspberry." University of Akron / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=akron1185892825.
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Amin, Hiren. "The vascular and anti-inflammatory activity of cyanidin-3-glucoside and its metabolites in human vascular endothelial cells." Thesis, University of East Anglia, 2015. https://ueaeprints.uea.ac.uk/54341/.
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High dietary consumption of anthocyanins has been associated with a reduced risk of cardiovascular disease (CVD), which is supported by evidence from human, animal and in vitro studies. However, owing to anthocyanins’ poor bioavailability and extensive metabolism, it is likely their metabolites are responsible for their reported health effects; yet the bioactivity of anthocyanin metabolites remains largely unknown. This thesis aimed to address this deficiency in current scientific literature by investigating the vascular and anti-inflammatory activity of cyanidin-3-glucoside (C3G), the most abundant anthocyanin in the UK diet, and 11 of its recently identified metabolites (including six synthetic metabolites) at physiological concentrations (0.1 – 10 µM) in a human endothelial cell model. Here protein and mRNA levels were established using ELISA and RT-qPCR, superoxide levels were quantified by spectrophotometric measure of cytochrome creduction and electron paramagnetic resonancespectroscopy, and nuclear factor kappa B (NF-κB) activation was established by flow cytometry. The data indicate that C3G, its A-ring degradant, phloroglucinaldehyde (PGA), and its phase II metabolite vanillic acid (VA) increased the basal expression of endothelial nitric oxide synthase (eNOS) by between 1.5- to-3 fold (p<0.05). In contrast, none of the compounds tested modulated angiotensin II (Ang II)-stimulated superoxide production and basal endothelin-1 expression in endothelial cells. Anti-inflammatory activity of the treatments was characterised by their effects upon oxidised low density lipoprotein (oxLDL) and cluster of differentiation 40 ligand (CD40L) stimulated expression of vascular cell adhesion molecule-1 (VCAM-1) and interleukin-6 (IL-6) in endothelial cells. Here, significant bioactivity of C3G metabolites was observed, as 7 out of 12 of the tested treatments reduced CD40L-induced VCAM-1 expression up to 65% (relative to control, p<0.05), eight compounds reduced CD40L-induced IL-6 production up to 95% (relative to control, p<0.05), and nine compounds reduced oxLDL-induced IL-6 protein secretion up to 99% of control incubations (p<0.05). Protocatechuic acid (PCA) and VA reduced VCAM-1 and IL-6 protein and mRNA levels under both stimulation conditions, and were therefore selected for further targeted investigation of transcription factor activity. Here IL-1β-induced activation of nuclear factor-kappa B (NF-κB) was significantly reduced by both PCA and VA (p<0.05). Therefore, anthocyanin metabolites appear to exert their effects on inflammatory chemokines through attenuation of NF-κB p65 phosphorylation in endothelial cells. In summary, the beneficial effects of anthocyanins in Page 3 vivo may arise, in part, from the anti-inflammatory activity of their metabolites, as the metabolites displayed significant anti-inflammatory activity and are found in the circulation at considerably higher concentrations than their unmetabolised precursor structures, hence likely contributing to the observed vascular activity in humans. These findings provide novel insight to bioactivity of anthocyanins and extend current knowledge in the field of anthocyanin research.
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Diemert, Lindsey. "A Sweet Cherry Feeding Trial in Healthy, Overweight Males: Anthocyanin Bioavailability and Inflammatory Biomarker Response." Thesis, The University of Arizona, 2011. http://hdl.handle.net/10150/203500.
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Background: Low-grade chronic inflammation has been implicated as a risk factor in prostate-related pathologies including benign hyperplasia and cancer. Sweet cherry containing the bioactive anthocyanin (ACN), has demonstrated tumor inhibitory action in model systems, specifically inhibition of inflammatory molecules and prostaglandin biosynthesis. Objective: To assess the urinary and plasma concentrations of ACN from the daily consumption of 3 cups of sweet cherries for 4 weeks and test the relationship of ACN levels and cherry consumption to inflammatory biomarkers in an at risk population. Results: Prostaglandin E2 Metabolite (PGEM) levels were reduced with cherry consumption in men with elevated baseline values. Conclusion: We conclude that 1c (142g) of sweet cherries 3 times daily for 4 weeks significantly reduced the COX-2 metabolite, PGEM, in men with elevated baseline levels. This was the first study to examine the chronic effects of daily sweet cherries on COX-2 inhibition in an at risk population.
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Casanova, Federico. "Colloidal stability of native and cross-linked casein micelles and their potential use as nanocarrier for cyanidin-3-O-glucoside." Universidade Federal de Viçosa, 2017. http://www.locus.ufv.br/handle/123456789/10417.
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Micelas de caseína (MCs) são estruturas supramoleculares naturais presentes no leite. Seu diâmetro hidrodinâmico médio é de 200 nm e apresenta um núcleo hidrofóbico e uma membrana hidrofílica. MCs podem ser usadas como nanocarreadores naturais para liberar várias moléculas de interesse. Apesar das MCs serem bastante estáveis ao calor, sua estrutura é altamente sensível a mudanças iônicas especialmente em pH ácido. Um interessante método para estabilizar a estrutura da caseína consiste na sua reticulação pela união de moléculas de caseínas por meio de ligações covalentes. Neste contexto, o objetivo desse presente trabalho é investigar a estabilidade de MCs reticuladas sob diferentes pHs, agentes dissociadores, temperatura e condições alcóolicas. Assim, verificar o seu potencial como nanocarreador para aprisionar cianidina-3-O- glicosídeo (C3G), um antocianina presente em várias frutas brasileiras que apresenta diversificada propriedade bioativa em condições ácidas. Dois agentes reticuladores foram avaliados: genipina (GP) e transglutaminase (Tgase). Nós apresentamos um estudo comparativo da estabilidade entre MCs nativas e MCs reticuladas com GP ou Tgase em função do pH. A estabilidade em diferentes temperaturas e concentrações de etanol foram investigadas em uma faixa de pH entre 2,0 - 7,0 e os resultados apresentaram que a reação de reticulação estabilizou as MCs sob as condições testadas. No entanto, GP não é reconhecida como GRAS (segura para aplicação em alimentos) a pesquisas adicionais sobre sua toxicidade devem ser requeridas para implementar o seu uso como reticulador em alimentos. Por essa razão, na segunda parte do nosso trabalho, nós restringimos somente nas MCs reticuladas com Tgase com a perspectiva do seu uso em aplicações alimentícias. Primeiramente nós investigamos sobre a possibilidade de interação entre as moléculas de caseína e C3G em condições ácida (pH 2,0) e neutra (pH 7,0). Desta forma, o uso de MCs reticuladas por Tgase como nanocarreadores de C3Ga pH 2,0 e a pH 7,0 foram exploradas. A constante de ligação tão bem quanto as forças dirigentes a diferentes valores de pH foram determinadas por meio de análises termodinâmicas a diferentes temperaturas. A pH 2,0, a associação hidrofóbica dirigiu as interações entre a caseína e C3G, enquanto a pH 7,0, as interações eletrostáticas são as forças dirigentes dominantes. MCs reticulada com Tgase não afeta as interações entre C3G e as caseínas significando que elas podem ser usadas como eficientes nanocarreadores para antocianinas como a C3G em condições ácidas.
Casein micelles (CMs) are natural supramolecular assemblies present in milk. Their average hydrodynamic diameter is about 200nm and they present a hydrophobic core and a hydrophilic shell. CMscan be used as natural nanocarriers to deliver various moleculesof interest. Although CMs are quite stable against heat, their structure is highly sensitive to ionic changes, especially at acid pH. An interesting method to stabilize casein structure consists on itscross-linking, by joining casein molecules through covalent bonds.In this context, the objective of the present work is first to investigate the stability of cross-linked CMs under different pH, dissociating agents, temperature, and ethanol conditions. Then, verify their potential use as nanocarrier for entrapped cyanidine-3-O-glucoside (C3G), an anthocyanin present in several Brazilian’s fruits, that shows diverse bioactive properties in acid conditions. Two cross-linking agents were evaluated: genipin (GP) and transglutaminase (Tgase). We present a comparative study of the stability between native CMs and CMs cross-linked with GP or Tgase as a function of pH. Stabilities at different temperatures and ethanol concentrations were investigated in a pH range between 7.0 – 2.0 and results showed that the cross-linkingreaction stabilized CMs under the conditions tested.However, GP is not recognized as GRAS (safe for food applications) and further researches on toxicity would be required to implement their use as a food-grade cross-linker. For this reason, in the second part of our work, we focalize only on Tgase cross-linked CMswith perspectives of using it for food applications.Firstly we investigated on the possible interaction between casein molecules and C3G under acidic (pH 2.0) and neutral (pH 7.0) conditions. Then, the use of Tgasecross-linked CMs as nanocarrier for C3G at pH 2.0 and at pH 7.0 was explored. Binding constant as well as driving forces at different pH values were determined by thermodynamic analysis at different temperatures. At pH 2.0, hydrophobic association drive the interactions between caseins and C3G, whereas at pH 7.0, electrostatic interactions are the dominant binding forces. CMs Cross-linking by Tgase don’t affect the interactions between C3G and caseins meaning it can be used as efficient nanocarriers for anthocyanins such as C3G under acid conditions.
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Davies, Gillian Mary. "Degradation of cyanide and metal cyanides using fungi." Thesis, University of Oxford, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.393787.
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CARUSO, ENRICO. "STUDY OF OXIDATIVE STRESS AND ANTIOXIDANT RESPONSE IN THE SGCA NULL DYSTROPHIC MOUSE MODEL." Doctoral thesis, Università degli Studi di Milano, 2018. http://hdl.handle.net/2434/570027.
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During my PhD, I mainly focus on the of dietary antioxidant and the role of oxidative stress in the progression of Muscular Dystrophy (MDs). MDs are genetic human diseases which are hallmarked by a progressive muscle wasting of variable severity, in the most severe cases this condition leads patients to wheelchair life and premature death due to respiratory and cardiac failure (Emery 2002). Mutations, in these pathologies, mainly affect the Dystrophin-associated Glycoprotein Complex (DGC); this multiprotein complex is located in the myofiber sarcolemma and links the fibers to the extracellular matrix conferring stability to fiber structure. The absence or the malfunction of the DGC leads to myofibers instability, which leads to fibers death and in time compromise muscle functionality. In the most severe cases MD patients would die of respiratory and cardiac failure.
Nowadays there is no definitive treatment for MDs that can cure the root of the pathology, although among the different approaches, many efforts are directed to slow down the progression of the disease to counteract the progressive degeneration and to improve patients life quality (Cossu & Sampaolesi 2007).
It is now very well established that the DGC not only plays a structural role for the myofiber stability, but also its stretch during contraction is essential for the activation of important signalling pathways. In fact, in literature is known that accumulation of reactive oxygen species (ROS) and oxidative stress contribute strongly to the worsening of MDs, suggesting that muscles affected by these diseases display an impairment in antioxidant signalling (Rando 1998; Rando 2002). In this study, we show that an cyanidin enriched diet is able to delay MD progression in the dystrophic mouse model Sgca null. In particular we display a morphological amelioration of muscle tissue organization, more fiber stability and rescue of muscle performance.
Moreover, the antioxidant diet is able to interfere with the proinflammatory environment, typical of these pathologies. Specifically, cyanidin impairs NF-kB translocation into the myonuclei, and prevent the expression of typical pro-inflammatory genes such as TNF- and iNOS.
Furthermore, we observe an increase of the antioxidant response in dystrophic mice fed with this particular diet. We found that the transcriptional levels of antioxidant genes (i.e. HO-1 and GCLC), in this scenario, are increased through the activity a specific transcription factor known as Nrf-2. We investigate on the signalling pathway that promote Nrf-2 nuclei localization, finding that AMPK activity is the crucial factor.
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Parab, Preeti. "Requirements for Cell-Free Cyanide Oxidation by Pseudomonas Fluorescens NCIMB 11764." Thesis, University of North Texas, 2000. https://digital.library.unt.edu/ark:/67531/metadc2614/.
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The involvement of cyanide oxygenase in the metabolism of pyruvate and a-ketoglutarate-cyanohydrin was investigated and shown to occur indirectly by the consumption of free cyanide arising from the cyanohydrins via chemical dissociation. Thus, free cyanide remains the substrate, for which the enzyme displays a remarkably high affinity (Kmapp,4 mM). A model for cyanide utilization is therefore envisioned in which the substrate is initially detoxified by complexation to an appropriate ligand followed by enzymatic oxidation of cyanide arising at sublethal levels via chemical dissociation. Putative cyanide oxygenase in cell extracts consumed both oxygen and NADH in equimolar proportions during cyanide conversion to CO2 and NH3 and existed separately from an unknown heat-stable species responsible for the nonenzymatic cyanide-catalyzed consumption of oxygen. Evidence of cyanide inhibition and nonlinear kinetics between enzyme activity and protein concentration point to a complex mechanism of enzymatic substrate conversion.
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Leahy, Christopher David. "The oxidation by peroxides of cyanides, cyanide complexes and related species." Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/46407.
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Wang, Chien-Sao. "Cell-Free Recovery and Isotopic Identification of Cyanide Degrading Enzymes from Pseudomonas Fluorescens." Thesis, University of North Texas, 1995. https://digital.library.unt.edu/ark:/67531/metadc278363/.
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Cell-free extracts from Pseudomonas fluorescens NCIMB 11764 catalyzed the degradation of cyanide into products that included C02, formic acid, formamide and ammonia. Cyanide-degrading activity was localized to cytosolic cell fractions and was observed at substrate concentrations as high as 100 mM. Two cyanide degrading activities were identified by: (i) the determination of reaction products stoichiometries, (ii) requirements for NADH and oxygen, and (iii) kinetic analysis. The first activity produced CO2 and NH3 as reaction products, was dependent on oxygen and NADH for activity, and displayed an apparent Km for cyanide of 1.2 mM. The second activity generated formic acid (and NH3) pfus formamide as reaction products, was oxygen independent, and had an apparent Km of 12 mM for cyanide. The first enzymatic activity was identified as cyanide oxygenase whereas the second activity consists of two enzymes, a cyanide nitrilase (dihydratase) and putative cyanide hydratase. In addition to these enzymes, cyanide-grown cells were also induced for formate dehydrogenase (FDH), providing a means of recycling NADH utilized by cyanide oxygenase.
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Fernandez, Ruby. "Cyanide Assimilation in Pseudomonas Fluorescens: Characterization of Cyanide Oxygenase as a Pterin-Dependent Multicomponent Enzyme Complex." Thesis, University of North Texas, 2004. https://digital.library.unt.edu/ark:/67531/metadc5548/.
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Cyanide utilization in Pseudomonas fluorescens NCIMB 11764 occurs via oxidative conversion to carbon dioxide and ammonia, the latter satisfying the nitrogen requirement. Substrate attack is initiated by an enzyme referred to as cyanide oxygenase (CNO), previously shown to require components in both high (H) (>30 kDa) and low (L) (<10 kDa) molecular weight cell fractions. In this study, tetrahydrobiopterin (H4biopterin) was identified as a cofactor in fraction L, thus making CNO appear as a pterin- dependent hydroxylase. CNO was purified 150-fold (specific activity 0.9 U/mg) and quantitatively converted cyanide to formate and ammonia as reaction products. When coupled with formate dehydrogenase, the complete enzymatic system for cyanide oxidation to carbon dioxide and ammonia was reconstituted. CNO was found to be an aggregate of known enzymes that included NADH oxidase (Nox), NADH peroxidase (Npx), cyanide dihydratase (CynD) and carbonic anhydrase (CA). A complex multi-step reaction mechanism is proposed in which Nox generates hydrogen peroxide which in turn is utilized by Npx to catalyze the oxygenation of cyanide to formamide accompanied by the consumption of one and two molar equivalents of oxygen and NADH, respectively. The further hydrolysis of formamide to ammonia and formate is thought to be mediated by CynD. The role of H4biopterin and of the enzyme CA in the proposed process remains unclear, but the involvement of each in reactive oxygen and radical chemistry is consistent with the proposed formation of such species in the catalytic process. H4biopterin may additionally serve as a protein stabilizing agent along with a protein co-purifying with CynD identified as elongation factor Tu, a known chaperone. At least two of the CNO components (Nox and CynD) are complex oligomeric proteins whose apparent association with Npx and CA appears to be favored in bacterial cells induced with cyanide allowing their purification in toto as a multiprotein enzyme complex.
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Chen, Jui-Lin. "Biochemical Identification of Molecular Components Required for Cyanide Assimilation in Pseudomonas fluorescens NCIMB 11764." Thesis, University of North Texas, 1998. https://digital.library.unt.edu/ark:/67531/metadc278624/.
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Utilization of cyanide as a nutritional nitrogen source in P. fluorescens NCIMB 11764 was shown to involve a novel metabolic mechanism involving nonenzymatic neutralization outside of cells prior to further enzymatic oxidation within. Several cyanide degrading enzymes were produced by NCIMB 11764 in response to growth or exposure to cyanide, but only one of these cyanide, oxygenase (CNO), was shown to be physiologically required for assimilation of cyanide as a growth substrate.
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Chou, Chia-Ni. "Purification of Cyanide-Degrading Nitrilase from Pseudomonas Fluorescens NCIMB 11764." Thesis, University of North Texas, 2010. https://digital.library.unt.edu/ark:/67531/metadc33224/.
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Cyanide is a well known toxicant that arises in the environment from both biological and industrial sources. Bacteria have evolved novel coping mechanisms for cyanide and function as principal agents in the biosphere for cyanide recycling. Some bacteria exhibit the unusual ability of growing on cyanide as the sole nitrogen source. One such organism is Pseudomonas fluorescens NCIMB 11764 (Pf11764) which employs a novel oxidative mechanism for detoxifying and assimilating cyanide. A unique complex of enzymes referred to as cyanide oxygenase (CNO) is responsible for this ability converting cyanide to ammonia which is then assimilated. Because one component of the four member CNO complex was previously shown to act on cyanide independent of the other members, its characterization was sought as a means of gaining a better understanding of the overall catalytic mechanism of the complex. Preliminary studies suggested that the enzyme belonged to a subset of nitrilase enzymes known as cyanide dihydratases (CynD), however, a cynD-like gene in Pf11764 could not be detected by PCR. Instead, a separate nitrilase (Nit) linked to cyanide metabolism was detected. The corresponding nit gene was shown to be one of a conserved set of nit genes traced to a unique cluster in bacteria known as Nit1C. To determine whether the previously described CynD enzyme was instead Nit, efforts were undertaken to isolate the enzyme. This was pursued by cloning and expressing the recombinant enzyme and by attempting to isolate the native enzyme. This thesis is concerned with the latter activity and describes the purification of a Nit-like cyanide-degrading nitrilase (NitCC) from Pf11764 to ~95% homogeneity. Purification was greatly facilitated by the discovery that fumaronitrile, as opposed to cyanide, was the preferred substrate for the enzyme (20 versus 1 U/mg protein, respectively). While cyanide was less effective as a substrate, the specificity for cyanide far outweighed that (10,000 fold) of the recombinant enzyme (NitPG) implying that the native NitCC protein purified in this work is different from that of the cloned recombinant. Further evidence of this was provided by molecular studies indicating that the two proteins differ in mass (34.5 and 38 kDa, respectively) and amino acid sequence. In summary, two different Nit enzymes are encoded by Pf11764. While the two share greater than 50% amino acid sequence identity, the results suggest that the native NitCC enzyme purified in this work functions better as a cyanide-degrading nitrilase and is one of four enzyme components comprising CNO required for Pf11764 cyanide assimilation.
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Silva, Avalos Juan G. (Juan Guillermo). "Isolation, Characterization and Physiological Studies of Cyanide-Utilizing Bacteria." Thesis, University of North Texas, 1991. https://digital.library.unt.edu/ark:/67531/metadc278291/.
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Ten bacteria capable of growth on the metal-cyano complex, tetracyanonickelate (II) {K2 [Ni(CN)J } (TCN), supplied as the sole nitrogen source, were isolated. Seven isolates were identified as pseudomonads while the remaining three were classified as Klebsiella species. In addition to TCN, all isolates were able to utilize KCN although it was significantly more toxic. The degradation of TCN was most complete when supplied at growth-limiting concentrations, did not occur when ammonia was present, and resulted in the formation of nickel cyanide [Ni(CN)2] as a degradation product.
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Nagappan, Olagappan. "Mechanisms of Cyanide Assimilation in Pseudomonas fluorescens NCIMB 11764." Thesis, University of North Texas, 1992. https://digital.library.unt.edu/ark:/67531/metadc278533/.
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Pseudomonas fluorescens NCIMB 11764 was capable of utilizing cyanide as a sole nitrogen source for growth. Cyanate (OCN") and S-cyanoalanine could also serve as nitrogenous substrates, but do not appear to play a role as intermediates in cyanide metabolism. Growth of this strain on cyanate as the sole nitrogen source led to the induction of an enzyme characterized as a cyanase (EC 3.5.5.3) based on its stoichiometric conversion of cyanate to ammonia, and dependence on bicarbonate for maximal activity. However, since cyanase activity was not elevated in cyanide-grown cells it was concluded that it serves no role in cyanide metabolism. Related studies aimed at examining a possible role for S-cyanoalanine as a cyanide-assimilation intermediate showed that while this compound also serves as a nitrogen source, it also is not important in cyanide metabolism. Studies focused on the utilization of free cyanide as a growth substrate led to the development of a fed-batch cultivation procedure greatly facilitating further experimentation aimed at the identification of cyanide metabolites. In addition to CO_2 and NH_3 as described earlier, two additional metabolites including formamide and formate were detected by using nC-NMR, HPLC, radioisotrapping methods and other analytical means. The formation of metabolites was shown to be induced after growth on cyanide with the relative product yields dependent on the availability of oxygen. These findings support earlier work in which an oxygen-dependent mechanism was proposed for the formation of C02 and NH3. However, at least two additional oxygen-independent pathways of cyanide conversion can be elaborated by this organism. One of these involves conversion to formate and ammonia while the other leads to the formation of formamide, which is not further degraded. Thus, growth on cyanide appears to occur by several mechanisms of chemical transformation presumably serving both detoxification and nutritional roles. Since two of these mechanisms generate ammonia, which is readily assimilated, growth is presumed to proceed via ammonia as a provisionary nitrogenous substrate.
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Dolghih, Elena. "Bacterial Cyanide Assimilation: Pterin Cofactor and Enzymatic Requirements for Substrate Oxidation." Thesis, University of North Texas, 2004. https://digital.library.unt.edu/ark:/67531/metadc4525/.
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Utilization of cyanide as the sole nitrogen source by Pseudomonas fluorescens NCIMB 11764 (Pf11764) occurs via oxidative conversion to carbon dioxide and ammonia, the latter satisfying the nitrogen requirement. Substrate attack is initiated oxygenolytically by an enzyme referred to as cyanide oxygenase (CNO), which exhibits properties of a pterin-dependent hydroxylase. The pterin requirement for Pf11764 CNO was satisfied by supplying either the fully (tetrahydro) or partially (dihydro) reduced forms of various pterin compounds at catalytic concentrations (0.5 µM). These compounds included, for example, biopterin, monapterin and neopterin, all of which were also identified in cell extracts. A related CNO-mediated mechanism of cyanide utilization was identified in cyanide-degrading P. putida BCN3. This conclusion was based on (i) the recovery of CO2 and NH3 as enzymatic reaction products, (ii) the dependency of substrate conversion on both O2 and NADH, and (iiii) utilization of cyanide, O2 and NADH in a 1:1:1 reaction stoichiometry. In contrast to findings reported for Pf11764, it was not possible to demonstrate a need for exogenously added pterin as a cofactor for the PpBCN3 enzyme system. However, results which showed that cells of PpBCN3 contained approximately seven times the amount of pterin as Pf11764 (of which a significant portion was protein-bound) were interpreted as indicating that sufficient bound CNO-cofactor exists, thus eliminating any need for a supplemental source.
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Pan, Guangliang. "Role of α-Keto Acids In Cyanide Detoxification and Assimilation by Pseudomonas Bacteria." Thesis, University of North Texas, 1998. https://digital.library.unt.edu/ark:/67531/metadc500761/.
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Cyanide was rapidly removed when added to culture supernatants of seven different Pseudomonas. The ability to remove cyanide was correlated with the accumulation of α-keto acids (pyruvate and α-ketoglutarate). These compounds react with cyanide forming less toxic cyanohydrins, thus conferring a mechanism for bacterial cyanide tolerance. When added to growth media the α-keto acids were shown also to serve as effective cyanide antagonists. While all bacteria tested accumulated α-keto acids, only those capable of utilizing cyanide as a nutritional nitrogen source were able to metabolize cyanohydrins. In P. fluorescens NCIMB 11764, the same enzyme (cyanide oxygenase) shown previously to be involved in cyanide metabolism appears responsible for cyanohydrin transformation. Keto acid excretion is believed to represent a new mechanism of bacterial cyanide detoxification with further enzymatic metabolism of the cyanohydrins helping to explain how cyanide can satisfy the nitrogen requirement in cyanide-utilizing bacteria.
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Ghosh, Pallab. "Linkage of a nitrilase-containing Nit1C gene cluster to cyanide utilization in Pseudomonas fluorescens NCIMB 11764." Thesis, University of North Texas, 2009. https://digital.library.unt.edu/ark:/67531/metadc10993/.
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Pseudomonas fluorescens NCIMB 11764 (Pf11764) is uniquely able to grow on the poison cyanide as its sole nitrogen source. It does so by converting cyanide oxidatively to carbon dioxide and ammonia, the latter being assimilated into cellular molecules. This requires a complex enzymatic machinery that includes nitrilase and oxygenase enzymes the nature of which are not well understood. In the course of a proteomics analysis aimed at achieving a better understanding of the proteins that may be required for cyanide degradation by Pf11764, an unknown protein of 17.8 kDa was detected in cells exposed to cyanide. Analysis of this protein by ESI-coupled mass spectrometry and bioinformatics searches gave evidence of strong homology with a protein (Hyp1) of unknown function (hypothetical) present in the bacterium Photorhabdus luminescens subsp. laumondii TTO1 (locus plu_1232). A search of available microbial genomes revealed a number of Hyp1 orthologs the genes of which are found in a conserved gene cluster known as Nit1C. Independent studies revealed that in addition to Hyp1, Pf11764 possesses a gene (nit) specifying a nitrilase enzyme whose closest homologue is a nitrilase found in Nit1C gene clusters (77% amino acid identity). DNA sequence analysis has further revealed that indeed, hyp1Pf11764 and nitPf11764 are contained in a cluster that includes also a gene specifying an oxygenase. Given the possible connection of Nit1C-endoded nitrilase and oxygenase enzymes to enzymatic cyanide degradation, there is strong reason for thinking that the genes specifying these enzymes contribute to bacterial growth on cyanide in those bacteria containing the Nit1C cluster. Because the biological function of the Hyp1 protein is currently unknown, it was cloned and the protein expressed in E. coli so that its properties could further be explored. Unfortunately, the expression of the protein in an insoluble form complicated these analyses. However, at least two lines of evidence suggest a possible role as a regulator of gene expression. First, over-expression of the protein was accompanied by the parallel elevation of the putative vector-encoded b-lactamase, implying that Hyp1Pf11764 can affect the expression of other genes. Second, a comparison of the amino acid sequence of select peptide fragments of Hyp1Pf11764, by conducting searches for homology with proteins in the existing nonredundant protein database, consistently revealed motifs in common with those present in bacterial response regulators that are part of two-component signal transduction systems widely distributed in bacteria.
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Akinpelu, Enoch Akinbiyi. "Thermodynamic study of the biodegradation of cyanide in wastewater." Thesis, Cape Peninsula University of Technology, 2017. http://hdl.handle.net/20.500.11838/2554.
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Thesis (DTech (Chemical Engineering))--Cape Peninsula University of Technology, 2017.The high rate of industrialisation in most developing countries has brought about challenges of wastewater management especially in the mineral processing industry. Cyanide has been used in base metal extraction processes due to its lixiviant properties thus, its presence in wastewater generated is inevitable. Furthermore, partial and/or the use of unsuitable treatment methods for such wastewater is a potential hazard to both human and the environment. There are several reports on biotechnological treatments of cyanide containing wastewater but few mineral processing industries have adopted this approach. Hence, the thermodynamic study of biodegradation of cyanide containing wastewater was undertaken. The primary aim of this study was to explore the application of bioenergetic models and biological stoichiometry to determine the functionality and thermodynamic requirements for cyanide degrading isolate (Fusarium oxysporum EKT01/02), grown exclusively on Beta vulgaris, for a system designed for the bioremediation of cyanidation wastewater. Chapter 2 reviews some of the applicable thermodynamic parameters such as enthalpy, entropy, heat of combustion, heat capacity, Gibbs energy, including stoichiometry models in relation to their applicability for microbial proliferation in cyanidation wastewater. The chapter places emphasis on the application of agro-industrial waste as a suitable replacement for refined carbon sources for microbial proliferation in bioremediation systems because such systems are environmentally benign. The choice of using agro-industrial waste is due to organic waste properties, i.e. agro-industrial waste is rich in nutrients and is generated in large quantities. Chapter 3 presents the materials and various standardised methods used to address the research gaps identified in chapter 2. For an organism to degrade free cyanide in wastewater, it must be able to survive and perform its primary function in the presence of such a toxicant. Chapter 4 exemplifies both molecular and biochemical characteristics of Fusarium oxysporum EKT01/02 isolated from the rhizosphere of Zea mays contaminated with a cyanide based pesticide. The molecular analyses confirmed the fungal isolate to be Fusarium oxysporum EKT01/02 and the nucleotide sequence of the isolates were deposited with National Centre for Biotechnology Information (NCBI) with accession numbers KU985430 and KU985431. The biochemical analyses revealed a wide substrate utilisation mechanism of the isolate dominated by aminopeptidase including nitrate assimilation capabilities. A preliminary investigation showed free cyanide degradation efficiency of 77.6% (100 mg CN-/L) after 5 days by the isolate. The excess production of extracellular polymeric substance (EPS) was attributed to the isolates’ strive to protect itself from cyanide toxicity.
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Jones, Lauren Brittany. "Defining Components Linked to Bacterial Nutritional Utilization of Cyanide as a Sole Nitrogen Source." Thesis, University of North Texas, 2019. https://digital.library.unt.edu/ark:/67531/metadc1505253/.
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One of the challenges in biology is placing a function on the myriad of gene sequences having become available from rapid advances in genome sequencing. One such example is a gene cluster (Nit1C) found in bacteria that is tied to the unusual ability of certain bacteria to grow when supplied cyanide as the sole nitrogen source. The term cyanotrophs has been applied to such bacteria, for which a genetic linkage between cyanotrophy and Nit1C was demonstrated for 10 separate bacteria. In addition to growth, cyanide induced the expression of Nit1C genes in all organisms tested, and in one case, deletion of one of the Nit1C genes (nitC) caused a loss of growth. Of the ten bacteria able to grow cyanotrophically, all gave evidence of harboring Nit1C on their genome except for two (Pseudomonas fluorescens Pf11764 and P. monteilii BCN3), which were sequenced and the presence of Nit1C was also confirmed. A broader search of bacteria identified 270 separate strains with the cluster, all limited to bacteria spanning the phyla Firmicutes, Actinobacteria, Proteobacteria and Cyanobacteria. Remarkably, many examples of a single representative of a given taxon contained Nit1C, most poignantly displayed by Pf11764 and PmBCN3; the interpretation being the cluster was likely acquired by horizontal gene transfer in response to cyanide as an environmental cue. Consistent with its absence in Archaea is the time line for the emergence of cyanide producing organisms (cyanogens) on earth dating back only 400-500 million years.
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Soares, Denise Josino. "Efeitos antioxidante e antiinflamatÃrio da polpa de pitanga roxa (Eugenia uniflora L.) sobre cÃlulas bucais humanas, aplicando experimentos in vitro e ex vivo." Universidade Federal do CearÃ, 2014. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=11608.
Full textAbstract:
CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel SuperiorA pitanga (Eugenia uniflora L.) à uma fruta tropical encontrada na regiÃo que compreende a parte central do Brasil e o Nordeste da Argentina. Este fruto possui baixo conteÃdo de lipÃdios, sendo rico em vitaminas e compostos bioativos, como os polifenÃis e carotenÃides. Devido ao uso da pitangueira na medicina popular e escassez de trabalhos cientÃficos sobre as propriedades antioxidantes e antiinflamatÃrias da pitanga roxa, o presente trabalho teve como objetivo investigar essas caracterÃsticas na polpa e no suco tropical de pitanga roxa adoÃado, usando experimentos in vitro e ex vivo. No presente estudo, a polpa de roxa foi separada em duas fraÃÃes (volÃtil e nÃo volÃtil), sendo o composto majoritÃrio de cada fraÃÃo identificado e quantificado. CÃlulas da gengiva humana (provenientes de seis voluntÃrios) foram expostas ao suco tropical de pitanga e ao composto majoritÃrio de cada fraÃÃo e analisadas quanto a atividade da catalase, o dano do DNA e a liberaÃÃo da interleucina 8 (IL-8). O experimento tambÃm foi realizado em cÃlulas dos fibroblastos gengivais humanos (HGF-1), cujas cÃlulas foram expostas aos compostos majoritÃrios das duas fraÃÃes da polpa de pitanga roxa e a liberaÃÃo da IL-8 foi analisada. A polpa de pitanga roxa apresentou valores mÃdios de sÃlidos solÃveis (8,33  0,06 ÂBrix), pH (3,12  0,01), acidez titulÃvel (1,76  0,20 g Ãcido cÃtrico/100 mL) e aÃÃcares totais (9,28  0,60 g glicose/100 mL) dentro dos padrÃes exigidos pela legislaÃÃo brasileira vigente. A referida polpa apresentou, ainda, nÃveis considerÃveis dos compostos bioativos: antocianinas (24,82  0,46 mg/100 mL), flavonÃides amarelos (11,33  0,66 mg/100 mL) e polifenÃis extraÃveis totais (26,85  0,30 mg GAE/100 mL), fazendo deste fruto uma boa fonte de antioxidantes naturais. Como composto majoritÃrio das fraÃÃes volÃtil e nÃo volÃtil da polpa de pitanga observa-se a oxidoselina-1,3,7(11)-trien-8-ona (85  4,01 Âg/mL) e a cianidina-3-glicosÃdeo (340  4,19 Âg/mL), respectivamente. O baixo pH do suco tropical de pitanga roxa adoÃado provocou uma reduÃÃo da atividade da catalase, enquanto a oxidoselina-1,3,7(11)-trien-8-ona e a cianidina-3-glicosÃdeo nÃo interferiram e nÃo foram capazes de inibir a atividade desta enzima. O suco tropical de pitanga roxa adoÃado preveniu o dano do DNA em cÃlulas da gengiva humana. Devido ao baixo nÃmero de voluntÃrios no experimento com o suco tropical de pitanga roxa adoÃado e os compostos majoritÃrios das fraÃÃes volÃtil e nÃo volÃtil da polpa de pitanga roxa, os resultados referentes à liberaÃÃo da IL-8 sÃo inconclusivos. Cianidina-3-glicosÃdeo e oxidoselina-1,3,7(11)-trien-8-ona apresentaram efeito antiinflamatÃrio em cÃlulas HGF-1.
Pitanga (Eugenia uniflora L.) is a tropical fruit found in the region that covers the central part of Brazil to Northern Argentina. This fruit has low lipid content, and is rich in bioactive compounds, such as polyphenols and carotenoids. In view of the use of pitanga tree in folk medicine and the shortage of scientific works about the antioxidative and anti-inflammatory effect of the purple pitanga, the present work aimed to investigate these characteristics in the pulp and in the sweetened tropical juice of purple pitanga, using in vitro and ex vivo experiments. In the present study, purple pitanga pulp was divided into two fractions (volatile and non-volatile), and the main compound of each fraction was identified and quantified. Human gingival cells (from six volunteers) were exposed to purple pitanga sweetened tropical juice and its main volatile and non-volatile compounds and analyzed by the catalase activity, DNA damage and interleukin 8 (IL-8) releases. The experiment was also performed with human gingival fibroblast (HGF-1), where cells were exposed to the individual main compounds from purple pitanga pulp and the IL-8 release was analyzed. Purple pitanga pulp presented mean values of soluble solids (8.33 Â 0.06 ÂBrix), pH (3.12 Â 0.01), titratable acidity (1.76 Â 0.20 g citric acid/100 mL) and total sugars (9.28 Â 0.60 g glucose/100 mL) within the standards required by current Brazilian law. This pulp also showed significant levels of the bioactive compounds: anthocyanins (24.82 Â 0.46 mg/100 mL), yellow flavonoids (11.33 Â 0.66 mg/100 mL) and total extractable polyphenols (26.85 Â 0.30 mg GAE/100 mL), making this product a good source of natural antioxidants. With regard to the main compound from volatile and non-volatile fractions of purple pitanga pulp, oxidoselina-1,3,7(11)-trien-8-one (85 Â 4.01 Âg/mL) was observed in the volatile fraction and cyanidin-3-glucoside (340 Â 4.19 Âg/mL )was observed in the non-volatile fraction. The low pH of the purple pitanga sweetened tropical juice decreases catalase activity, while oxidoselina-1,3,7(11)-trien-8-one and cyanidin-3-glucoside did not interfere and were not able to inhibit the activity of this enzyme. Purple pitanga sweetened tropical juice prevented DNA damage in human gingival cells. Due to the low number of volunteers in the experiment with purple pitanga sweetened tropical juice and the main compounds from volatile and non-volatile fractions of purple pitanga pulp, the results regarding the IL-8 release are inconclusive. Cyanidin-3-glucoside and oxidoselina-1,3,7(11)-trien-8-one presented anti-inflammatory effects in HGF-1 cells.
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Soares, Denise Josino. "Efeitos antioxidante e antiinflamatório da polpa de pitanga roxa (Eugenia uniflora L.) sobre células bucais humanas, aplicando experimentos in vitro e ex vivo." reponame:Repositório Institucional da UFC, 2014. http://www.repositorio.ufc.br/handle/riufc/14958.
Full textAbstract:
SOARES, D. J. Efeitos antioxidante e antiinflamatório da polpa de pitanga roxa (Eugenia uniflora L.) sobre células bucais humanas, aplicando experimentos in vitro e ex vivo. 2014. 98 f. Tese (Doutorado em Ciência e Tecnologia de Alimentos) - Centro de Ciências Agrárias, Universidade Federal do Ceará, Fortaleza, 2014.Submitted by Daniel Eduardo Alencar da Silva (dealencar.silva@gmail.com) on 2015-01-26T17:59:57Z No. of bitstreams: 1 2014_tese_djsoares.pdf: 2572830 bytes, checksum: 5fcdb95b76b4c0c19e882eb36d8865b7 (MD5)
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Pitanga (Eugenia uniflora L.) is a tropical fruit found in the region that covers the central part of Brazil to Northern Argentina. This fruit has low lipid content, and is rich in bioactive compounds, such as polyphenols and carotenoids. In view of the use of pitanga tree in folk medicine and the shortage of scientific works about the antioxidative and anti-inflammatory effect of the purple pitanga, the present work aimed to investigate these characteristics in the pulp and in the sweetened tropical juice of purple pitanga, using in vitro and ex vivo experiments. In the present study, purple pitanga pulp was divided into two fractions (volatile and non-volatile), and the main compound of each fraction was identified and quantified. Human gingival cells (from six volunteers) were exposed to purple pitanga sweetened tropical juice and its main volatile and non-volatile compounds and analyzed by the catalase activity, DNA damage and interleukin 8 (IL-8) releases. The experiment was also performed with human gingival fibroblast (HGF-1), where cells were exposed to the individual main compounds from purple pitanga pulp and the IL-8 release was analyzed. Purple pitanga pulp presented mean values of soluble solids (8.33 ± 0.06 °Brix), pH (3.12 ± 0.01), titratable acidity (1.76 ± 0.20 g citric acid/100 mL) and total sugars (9.28 ± 0.60 g glucose/100 mL) within the standards required by current Brazilian law. This pulp also showed significant levels of the bioactive compounds: anthocyanins (24.82 ± 0.46 mg/100 mL), yellow flavonoids (11.33 ± 0.66 mg/100 mL) and total extractable polyphenols (26.85 ± 0.30 mg GAE/100 mL), making this product a good source of natural antioxidants. With regard to the main compound from volatile and non-volatile fractions of purple pitanga pulp, oxidoselina-1,3,7(11)-trien-8-one (85 ± 4.01 µg/mL) was observed in the volatile fraction and cyanidin-3-glucoside (340 ± 4.19 µg/mL )was observed in the non-volatile fraction. The low pH of the purple pitanga sweetened tropical juice decreases catalase activity, while oxidoselina-1,3,7(11)-trien-8-one and cyanidin-3-glucoside did not interfere and were not able to inhibit the activity of this enzyme. Purple pitanga sweetened tropical juice prevented DNA damage in human gingival cells. Due to the low number of volunteers in the experiment with purple pitanga sweetened tropical juice and the main compounds from volatile and non-volatile fractions of purple pitanga pulp, the results regarding the IL-8 release are inconclusive. Cyanidin-3-glucoside and oxidoselina-1,3,7(11)-trien-8-one presented anti-inflammatory effects in HGF-1 cells.
A pitanga (Eugenia uniflora L.) é uma fruta tropical encontrada na região que compreende a parte central do Brasil e o Nordeste da Argentina. Este fruto possui baixo conteúdo de lipídios, sendo rico em vitaminas e compostos bioativos, como os polifenóis e carotenóides. Devido ao uso da pitangueira na medicina popular e escassez de trabalhos científicos sobre as propriedades antioxidantes e antiinflamatórias da pitanga roxa, o presente trabalho teve como objetivo investigar essas características na polpa e no suco tropical de pitanga roxa adoçado, usando experimentos in vitro e ex vivo. No presente estudo, a polpa de roxa foi separada em duas frações (volátil e não volátil), sendo o composto majoritário de cada fração identificado e quantificado. Células da gengiva humana (provenientes de seis voluntários) foram expostas ao suco tropical de pitanga e ao composto majoritário de cada fração e analisadas quanto a atividade da catalase, o dano do DNA e a liberação da interleucina 8 (IL-8). O experimento também foi realizado em células dos fibroblastos gengivais humanos (HGF-1), cujas células foram expostas aos compostos majoritários das duas frações da polpa de pitanga roxa e a liberação da IL-8 foi analisada. A polpa de pitanga roxa apresentou valores médios de sólidos solúveis (8,33 ± 0,06 °Brix), pH (3,12 ± 0,01), acidez titulável (1,76 ± 0,20 g ácido cítrico/100 mL) e açúcares totais (9,28 ± 0,60 g glicose/100 mL) dentro dos padrões exigidos pela legislação brasileira vigente. A referida polpa apresentou, ainda, níveis consideráveis dos compostos bioativos: antocianinas (24,82 ± 0,46 mg/100 mL), flavonóides amarelos (11,33 ± 0,66 mg/100 mL) e polifenóis extraíveis totais (26,85 ± 0,30 mg GAE/100 mL), fazendo deste fruto uma boa fonte de antioxidantes naturais. Como composto majoritário das frações volátil e não volátil da polpa de pitanga observa-se a oxidoselina-1,3,7(11)-trien-8-ona (85 ± 4,01 µg/mL) e a cianidina-3-glicosídeo (340 ± 4,19 µg/mL), respectivamente. O baixo pH do suco tropical de pitanga roxa adoçado provocou uma redução da atividade da catalase, enquanto a oxidoselina-1,3,7(11)-trien-8-ona e a cianidina-3-glicosídeo não interferiram e não foram capazes de inibir a atividade desta enzima. O suco tropical de pitanga roxa adoçado preveniu o dano do DNA em células da gengiva humana. Devido ao baixo número de voluntários no experimento com o suco tropical de pitanga roxa adoçado e os compostos majoritários das frações volátil e não volátil da polpa de pitanga roxa, os resultados referentes à liberação da IL-8 são inconclusivos. Cianidina-3-glicosídeo e oxidoselina-1,3,7(11)-trien-8-ona apresentaram efeito antiinflamatório em células HGF-1.
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Ellison, P. A., A. M. Jedele, T. E. Barnhart, R. J. Nickles, D. Murali, and O. T. DeJesus. "Production of [11C]cyanide for the synthesis of indole-3-[1-11C]acetic acid and PET imaging of auxin transport in living plants." Helmholtz-Zentrum Dresden - Rossendorf, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-166188.
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Introduction
Since its development by Al Wolf and colleagues in the 1970s1, [11C]cyanide has been a useful synthon for a wide variety of reactions, most notably those producing [1-11C]-labeled amino acids2. However, despite its position as rote gas-phase product, the catalytic synthesis is difficult to optimize and often only perfunctorily dis-cussed in the radiochemical literature. Recently, [11C]CN– has been used in the synthesis of indole-3-[1-11C]acetic acid ([11C]IAA), the principal phytohormone responsible for a wide variety of growth and development functions in plants3. The University of Wisconsin has expertise in cyclotron production and radiochemistry of 11C and previous experience in the PET imaging of plants4,5. In this abstract, we present work on optimizing [11C]CN– production for the synthesis of [11C]IAA and the PET imaging of auxin transport in living plants.
Material and Methods
[11C]CH4 was produced by irradiating 270 psi of 90% N2, 10% H2 with 30 µA of 16.1 MeV protons from a GE PETtrace cyclotron. After irradiation, the [11C]CH4 was converted to [11C]CN– by passing through a quartz tube containing 3.0 g of Pt wire and powder between quartz wool frits inside a 800–1000 ˚C Carbolite tube furnace. The constituents and flow rate of the [11C]CH4 carrier gas were varied in an effort to optimize the oven\'s catalytic production of [11C]CN– from CH4 and NH3. The following conditions were investigated:
i. Directly flowing irradiated target gas versus trapping, purging and releasing [11C]CH4 from a −178 ˚C HayeSep D column in He through the Pt furnace.
ii. Varying the amount of anhydrous NH3 (99.995%) mixed with the [11C]CH4 carrier gas prior to the Pt furnace. Amounts varied from zero to 35 % of gas flow.
iii. Varying the purity of the added NH3 gas with the addition of a hydride gas purifier (Entegris model 35KF), reducing O2 and H2O impurities to < 12 ppb.
iv. Varying the flow rate of He gas carrying trapped, purged and released [11C]CH4.
After flowing through the Pt furnace, the gas stream was bubbled through 300 µL of DMSO containing IAA precursor gramine (1 mg), then passed through a 60×5 cm column containing ascarite to absorb [11C]CO2, followed by a −178˚C Porapak Q column to trap [11C]CH4 and [11C]CO.
After bubbling, the DMSO/gramine vial was heated to 140 ˚C to react the gramine with [11C]CN–, forming the intermediate indole-3-[1-11C]acetonitrile ([11C]IAN), which was subsequently purified by solid phase extraction (SPE). The reaction mixture was diluted into 20 mL water and loaded onto a Waters Sep-Pak light C18 cartridge, followed by rinsing with 5 mL of 0.1% HCl : acetonitrile (99 : 1) and 10 mL of the same mixture in ratio 95 : 5, and finally eluted with 0.5 mL of diethyl ether. The ether was subsequently evaporated under argon flow, followed by the hydrolysis of [11C]IAN to [11C]IAA with the addition of 300 µL 1 M NaOH and heating to 140 ˚C for 5 minutes. After hydrolysis, the solution was neutralized with 300 µL 1 M HCl and purified using preparative high-performance liquid chromatography (HPLC) using a Phenomenex Luna C18 (10μ, 250×10mm) column with a mobile phase acetonitrile : 0.1% formic acid in H2O (35 : 65) at flow rate of 3 mL/min. The [11C]IAA peak, eluting at 12 minutes, was collected and rotary evaporated to dryness, then again after the addition of 5 mL acetonitrile, followed by its reconstitution in 50 µL of water. Analytical HPLC was performed on the [11C]IAA before and after this evaporation procedure using a Phenomenex Kinetex C18 (2.6μ, 75× 4.6 mm) column with a linear gradient elution over 20 minutes of 10 : 90–30 : 70 (acetonitrile : 0.1% formic acid) at a 1 mL/min flow rate, eluting at 7.6 minutes.
The transport of [11C]IAA was monitored following administration through the severed petiole of rapid cycling Brassica oleracea (rcBo) using a Siemens microPET P4 scanner. Transport was compared following administration to the first true leaf versus the final fully formed leaf in plants with and without exposure to the polar auxin transport inhibitor naphthylphthalamic acid (NPA).
Results and Conclusion
Optimization of the [11C]CN– gas phase chemistry was performed using two key metrics for measuring conversion yield. First is the fraction of total produced radioactivity that trapped in the DMSO/gramine solution (denoted %DMSO), and second, the fraction of DMSO/gramine-trapped activity that was able to react with gramine to form [11C]IAN (denoted %CN–). Under certain conditions, the former of these metrics experienced significant losses due to unconverted [11C]CH4 or through combustion, forming [11C]CO2 or [11C]CO. The latter metric experienced losses due to production of incomplete oxidation products of the CH4-NH3 reaction, such as methylamine. Total [11C]CH4 to [11C]CN– con-version yields is reported by the product of the two metrics. It was initially hypothesized that the irradiation of a 90% N2, 10% H2 target gas would produce sufficient in-target-hot-atom-produced NH3 to convert [11C]CH4 to [11C]CN– in the Pt furnace. However, conversion yields were found to be low and highly variable, with 13 ± 8 % trapping in DMSO/gramine, 9 ± 9 % of which reacted as CN– (n = 15). While in disagreement with previous reports1, this is likely as a result the batch irradiation conditions resulting ammonia losses in the target chamber and along the tubing walls. Yields and reproducibility were improved when combining the target gas with a stream of anhydrous NH3 gas flow with conversion yields reported in TABLE 1. However, these yields remained undesirably low, potentially as a result of the 10% H2 carrier gas having an adverse effect on the oxidative conversion of [11C]CH4 to [11C]CN–. To remedy this, the irradiated target gas was trapped, purged, released in He and combined with NH3 gas before flowing through the Pt furnace. Initial experiments using 99.995% anhydrous NH3 gas resulted in very poor (< 0.1%) [11C]CN– yields as a result of nearly quantitative combustion forming [11C]CO2. Installation of a hydride gas purifier to reduce O2 and H2O impurities in NH3 improved yields for CH4 in He, but did not significantly affect those from [11C]CH4 in N2/H2 target gas. In disagreement with previous reports2, conversion yields were found to be highly sensitive to overall carrier gas flow rate, with lower flow rates giving the best yields, as shown in TABLE 1. Optimization experiments are continuing.
The total decay-corrected yield for the 1 hour synthesis of [11C]IAA in 50 µL of water is 2.3 ± 0.7 %, based on the total produced [11C]CH4 with a specific activity ranging from 1–100 GBq/µmol. The principal radiochemical impurity was determined to be indole-3-carboxylic acid. The SPE procedure isolating the [11C]IAN intermediate product was optimized to minimize this impurity in the final sample.
After a rapid distribution of the administered [11C]IAA through the cut petiole and throughout the rcBO plant, upward vascular transport of auxin and downward polar auxin transport was visualized through time-activity curves (TACs) of regions of interest along the shoot. Comparison of these TACS with and without exposure to NPA yields insight into the fundamental physiological process of polar auxin transport in plants.
In conclusion, the Pt-catalyzed oxidative conversion of [11C]CH4 and NH3 to [11C]CN– is a challenging process to optimize and highly sensitive to carrier gas composition and flow rate. Optimization for our experimental conditions yielded several results which disagreed with previous reports. [11C]IAA produced using [11C]CN– is well suited for PET imaging of polar auxin transport in living plants.
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Zlosnik, James Edward Arthur. "Cyanide and the cyanide insensitive oxidase in Pseudomonas aeruginosa." Thesis, Imperial College London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.421885.
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Marshall, Laura J. "Novel methodology for the synthesis of ¹³C-Labelled phenols and its application to the total synthesis of polyphenols." Thesis, University of St Andrews, 2010. http://hdl.handle.net/10023/875.
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The base-catalysed reaction of 4H-pyran-4-one with a range of nucleophiles, namely diethyl malonate, ethyl acetoacetate, nitromethane, acetylacetone and ethyl cyanoacetate, was developed as a reliable, high yielding method for the preparation of para-substituted phenols. The methodology was extended to include the use of the substituted pyranones, maltol, 2,6-dimethyl-4H-pyran-4-one and diethyl chelidonate. Reactions were studied using conventional heating methods and microwave irradiation. Microwave irradiation had definite beneficial effects, with improved yields, reduced reaction times and cleaner reaction profiles. The potential of this methodology was examined for the regioselective placement of ¹³C-atoms into benzene rings using ¹³C-labelled nucleophiles or ¹³C-labelled 4H-pyran-4-ones. [3,5-13C₂]4H-Pyran-4-one and [2,6-13C₂]4H-pyran-4-one were prepared from various ¹³C-labelled versions of triethyl orthoformate and acetone. This methodology was applied to the synthesis of [1,3,5-¹³C₃]gallic acid, via the base-catalysed reaction of [3,5-¹³C₂]4H-pyran-4-one with diethyl [2-¹³C]malonate, followed by subsequent transformations to yield [1,3,5-¹³C₃]gallic acid. The preparation of [2-¹³C]phloroglucinol was carried out via [2-¹³C]resorcinol, with regioselective placement of a single ¹³C-atom into the aromatic ring. This was accomplished from non-aromatic precursors, with the source of the ¹³C-atom being [¹³C]methyl iodide. The key step in this synthesis was the introduction of the third hydroxyl group, which was achieved using a modified iridium-catalysed C-H activation/borylation/oxidation procedure. The scope of an existing C-H activation/borylation reaction was modified and expanded to include a range of protected resorcinol derivatives. A catalyst system was developed which allowed high conversion to the intermediate arylboronic acids, followed by oxidation using aqueous Oxone® to yield the corresponding phenols. Finally, to demonstrate the potential of these new methods for application in the synthesis of isotopically labelled natural products and polyphenols, the syntheses of ¹³C-labelled anthocyanins were studied. A route was developed that could be applied to the synthesis of either cyanidin-3-glucoside or delphinidin-3-glucoside. Only the final coupling/cyclisation step to yield the desired anthocyanin targets remains to be carried out.
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Xie, Feng. "Solvent extraction of copper and cyanide from waste cyanide solution." Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/25746.
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The potential use of two commercial extractants, LIX 7950, a guanidine derivative, and LIX 7820, a solvent mixture of quaternary amine and nonylphenol, for recovery of copper and cyanide from waste cyanide solution has been investigated. Low equilibrium pH favors copper extraction while a high molar ratio of cyanide to copper depresses the copper loading. It is confirmed that Cu(CN)²⁻₃ is preferentially extracted over Cu(CN) ³⁻₄ and CN- by the extractants.
Solvent extraction of the mixture of metal cyano complexes shows a selectivity order as follows: Zn > Ni > Cu > Fe. The presence of SO²⁻₄ or S₂O²⁻₃ shows an insignificant effect on copper extraction while SCN- ions may potentially compete for the available extractant with copper cyanide species and thus depress copper extraction significantly. Both extractants exhibit an affinity sequence as SCN- > CNO- > CN-> S₂O²⁻₃. The selectivity order of different anions with the extractants can be explained by the interrelated factors including anion hydration, charge density, compatibility of the formed complex with the organic phase and the geometry effect.
The extraction of Cu(CN)²⁻₃ with LIX 7950 is exothermic with an enthalpy change (ΔH°) of -191 kJ/mol. The copper extraction with LIX 7820 has little change when the temperature is varied from 25 °C to 45 °C. For both extractants, the loaded copper and cyanide can be stripped efficiently by a moderately strong NaOH solution. Further increase in NaOH concentration results in the formation of a third phase. The presence of NaCN can facilitate stripping of the loaded copper and cyanide by favoring the formation of Cu(CN)³⁻₄ in the stripping solution.
The important findings suggest a possible solution to the separation of metal cyanide species and free cyanide in the cyanide effluent. Both extractants can be used in a SX circuit for pre-concentrating copper into a small volume of strip solution which can be further treated by
electrowinning, AVR, SART or similar processes to recover copper products and cyanide. The free cyanide will remain in the raffinate solution from solvent extraction circuit which allows for the potential recycling of the barren solution to the gold cyanidation process.
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Johansson, Annelie. "Guldbrytningens miljö- och hälsoeffekter : En jämförande studie mellan tre exempel på guldgruvor i Kongo, Peru och Sverige." Thesis, Linnéuniversitetet, Institutionen för biologi och miljö (BOM), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-36079.
Full textAbstract:
Guld är ett grundämne och den bästa elektriska ledaren i tekniska apparater. Denna studie utvärderar vilka effekter guldbrytningen har på människors hälsa och miljö. Studien behandlar tre länder och hur de har påverkats av guldföretagen som opererar i respektive land. Det har framkommit att cyanid och kvicksilver har förödande effekter för människors hälsa i både Peru och Kongo. Problemet är att arbetsnormer och säkerhetsrutiner inte efterlevs. Sjukdomar som drabbat folk i Peru är bl.a. förlamning, leukemi, huvudvärk, utslag med mera. Dessa sjukdomar orsakades av en kvicksilverolycka. I Kongo utsätts arbetarna dagligen för kontakt med kvicksilver. Mark, vattendrag och grundvatten har blivit påverkade cyanid och kvicksilver. Gruvan i Sverige använder sig istället av kemikalien danafloat507 som är biologiskt nedbrytbar. Den kalkrika avfallsprodukten har haft positiv effekt på fisk och växter i det omgivande vattendrag.Gold is a chemical element and the best electrical conductor in technological devices. This study shows the impact that gold mining has on health and the environment. The study addresses three countries and how they have been affected by gold companies operating in each country. It has turned out that cyanide and mercury have devastating effects on the health of humans in both Peru and Congo. The problem is that labor standards and safety procedures are not adhered to. Diseases affecting people in Peru are paralysis, leukemia, headaches, rashes etc. This was due to a mercury accident. In Congo workers are daily exposed to mercury. Soil, rivers and groundwater has been affected by cyanide and mercury. A goldmine in Sweden is instead using danafloat507 a chemical that is biodegradable. The water from the mine is hence rich in lime and it has a positive effect on fish and plants.
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Mekuto, Lukhanyo. "Biodegradation of cyanide and subsequent nitrification-aerobic denitrification in cyanide containing watewater." Thesis, Cape Peninsula University of Technology, 2014. http://hdl.handle.net/20.500.11838/868.
Full textAbstract:
Thesis submitted in fulfilment of the requirements for the degree
Master of Technology: Chemical Engineering
in the Faculty of
Engineering
at the
Cape Peninsula University of Technology
2014Environmental legislation focusing on wastewater disposal in industries that utilise cyanide and/or cyanide-related compounds has become increasingly stringent worldwide, with many companies that utilise cyanide products required to abide by the Cyanide International Code associated with the approval of process certifications and management of industries which utilise cyanide. This code enforces the treatment or recycling of cyanide-contaminated wastewater. Industries such as those involved in mineral processing, photo finishing, metal plating, coal processing, synthetic fibre production, and extraction of precious metals, that is, gold and silver, contribute significantly to cyanide contamination in the environment through wastewater. As fresh water reserves throughout the world are low, cyanide contamination in water reserves threatens not only the economy, but also endangers the lives of living organisms that feed from these sources, including humans. In the mining industry, dilute cyanide solutions are utilised for the recovery of base (e.g. Cu, Zn, Ni, etc.) and precious metals (e.g. Au, Ag, etc.). However, for technical reasons, the water utilised for these processes cannot be recycled upstream of the mineral bioleaching circuit as the microorganisms employed in mineral bioleaching are sensitive to cyanide and its complexes, and thus the presence of such compounds would inhibit microbial activity, resulting in poor mineral oxidation. The inability to recycle the water has negative implications for water conservation and re-use, especially in arid regions. A number of treatment methods have been developed to remediate cyanide containing wastewaters. However, these chemical and physical methods are capital intensive and produce excess sludge which requires additional treatment. Furthermore, the by-products that are produced through these methods are hazardous. Therefore, there is a need for the development of alternative methods that are robust and economically viable for the bioremediation of cyanide-contaminated wastewater. Biological treatment of free cyanide in industrial wastewaters has been proved a viable and robust method for treatment of wastewaters containing cyanide. Several bacterial species, including Bacillus sp., can degrade cyanide to less toxic products, as these microorganisms are able to use the cyanide as a nitrogen source, producing ammonia and carbon dioxide. These bacterial species secrete enzymes that catalyse the degradation of cyanide into several end-products. The end-products of biodegradation can then be utilised by the microorganisms as nutrient sources. This study focused on the isolation and identification of bacterial species in wastewater containing elevated concentrations of cyanide, and the assessment of the cyanide biodegradation ability of the isolates. Thirteen bacterial isolates were isolated from electroplating wastewater by suppressing the growth of fungal organisms and these species were identified as species belonging to the Bacillus genus using the 16S rDNA gene. A mixed culture of the isolates was cultured in nutrient broth for 48 hours at 37°C, to which FCN as KCN was added to evaluate the species‟ ability to tolerate and biodegrade cyanide in batch bioreactors. Subsequently, cultures were supplemented solely with agro-waste extracts, that is, Ananas comosus extract (1% v/v), Beta vulgaris extract (1% v/v), Ipomea batatas extract (1% v/v), spent brewer‟s yeast (1% v/v) and whey (0.5% w/v), as the primary carbon sources. Owing to the formation of high ammonium concentration from the cyanide biodegradation process, the nitrification and aerobic denitrification ability of the isolates, classified as cyanide-degrading bacteria (CDB) was evaluated in a batch and pneumatic bioreactor in comparison with ammonia-oxidising bacteria (AOB). Furthermore, the effects of F-CN on the nitrification and aerobic denitrification was evaluated assess the impact of F-CN presence on nitrification. Additionally, optimisation of culture conditions with reference to temperature, pH and substrate concentration was evaluated using response surface methodology. Using the optimised data, a continuous biodegradation process was carried out in a dual-stage packed- bed reactor combined with a pneumatic bioreactor for the biodegradation of F-CN and subsequent nitrification and aerobic denitrification of the formed ammonium and nitrates. The isolated bacterial species were found to be gram positive and were able to produce endospores that were centrally located; using the 16S rDNA gene, the species were found to belong to the Bacillus genus. The species were able to degrade high cyanide concentration in nutrient broth with degradation efficiencies of 87.6%, 65.4%, 57.0% and 43.6% from 100 mg F-CN/L, 200 mg F-CN/L, 300 mg F-CN/L, 400 mg F-CN/L and 500 mg F-CN/L respectively over a period of 8 days. Additionally, the isolates were able to degrade cyanide in an agro-waste supported medium, especially in a medium that was supplemented with whey which achieved a degradation efficiency of 90% and 60% from 200 mg F-CN/L and 400 mg F-CN/L, respectively over a period of 5 days. The nitrification ability of the isolates was evaluated and the removal of NH4 +/NO3 - by the CDB and AOB in both shake flasks and pneumatic bioreactor was determined to be pH dependent. The maximum NH4 +/NO3 - removal evaluated over a period of 8 days for CDB and 15 days for AOB, observed at pH 7.7 in shake flasks, was 75% and 88%, respectively, in the absence of F-CN. Similarly, the removal of NH4 +/NO3 - in a pneumatic bioreactor was found to be 97.31% for CDB and 92% for AOB, thus demonstrating the importance of aeration in the designed process. The nitrification by CDB was not inhibited by cyanide loading up to a concentration of 8 mg FCN/ L, while the AOB were inhibited at cyanide loading concentration of 1 mg F-CN/L. The CDB removed the NH4 +/NO3 - in PBSs operated in a fed-batch mode, obtaining efficiencies >99% (NH4 +) and 76 to 98% (NO3 -) in repeated cycles (n = 3) under F-CN (≤8 mg F-CN/L). The input variables, that is, pH, temperature and whey-waste concentration, were optimised using a numerical optimisation technique where the optimum conditions were found to be: pH 9.88, temperature 33.60 °C and whey-waste concentration 14.27 g/L, under which 206.53 mg CN-/L in 96 h can be biodegraded by the microbial species from an initial cyanide concentration of 500 mg F-CN/L. Furthermore, using the optimised data, cyanide biodegradation in a continuous mode was evaluated in a dual-stage packed-bed bioreactor connected in series to a pneumatic bioreactor system used for simultaneous nitrification including aerobic denitrification. The whey-supported Bacillus sp. culture was not inhibited by the free cyanide concentration of up to 500 mg F-CN/L, with an overall degradation efficiency of ≥99% with subsequent nitrification and aerobic denitrification of the formed ammoniu and nitrates over a period of 80 days.
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Larsen, Morten. "Plant uptake of cyanide." Kgs. Lyngby : Institute of Environment & Resources, Technical University of Denmark, 2005. http://www.er.dtu.dk/publications/fulltext/2005/MR2005-044.pdf.
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Solis, Jose S. "Thermodynamics of cyanide complexes." Thesis, Solis, Jose S. (1995) Thermodynamics of cyanide complexes. PhD thesis, Murdoch University, 1995. https://researchrepository.murdoch.edu.au/id/eprint/52731/.
Full textAbstract:
The work described in this thesis was to study the thermodynamics of the binding of cyanide to metal ions of relevance to the hydrometallurgical processing of gold. In particular, to produce reliable and accurate thermodynamic data needed to develop reliable chemical speciation models for the gold-refining industry, especially with regard to the high saline conditions of many Australian operations.
The stability constants of binary and ternary Cu(I) systems were studied using potentiometric glass electrode titration and evaluation of results by the ESTA suite of computer programs. In particular, the study of the Cu(I)-CN- system produced four major binary species in the conditions studied. The stability constants for the three species, Cu(CN)2-, Cu(CN)32-, and Cu(CN)43- are reported. The Cu(I)-NH3 system was attempted but oxidation of Cu(I) in the presence of ammonia was observed to be fast even in the absence of air. The presence of a high Cl" concentration stabilizes Cu(I) and since it also complexes with the metal the ternary system of Cu(I)-NH3-Cl- was considered. This study has established the existence of three ternary species, Cu(NH3)Cl°, CuNH3Cl2- and Cu(NH3)2Cl° together with the binary Cu(NH3)+ in the conditions of the present study. The other ternary system, Cu(I)-NH3-CN-, was studied but no analysis could be made with the present evaluation method. Failure of these experiments may be due to the closeness of the protonation constants of cyanide and ammonia in this medium, thus making it difficult to detect the minor effects in the experimental data which may arise from the ternary complex formation. Also, the experiment is restricted from the variation of the free cyanide and ammonia concentration because of the oxidation of Cu(I), volatility of NH3 at high p[H] and the volatility of HCN at low p[H].
Measurements of heat of reactions of common metal-cyanide systems were calorimetrically determined by the isoperibol continuous titration calorimeter. Enthalpies of metal-cyanide complexation were determined from these calorimetric measurements. Included in this study was the measurement of the heat of ionization of water and HCN as they were relevant to the metal-cyanide heats of reaction studies. These two systems were studied at variable ionic strength.
The solubility of AgCN and CuCN in HCN aqueous solution was studied. Another method of deriving equilibrium constants is from solubility measurements. The apparent solubility product constant of both AgCN and CuCN were sucessfully measured using the pH variation method.
Heat capacity measurements were conducted with cyanide solution using the Picker-flow calorimeter. Measurement of the volumetric heat capacities required densities which were measured accurately using a Vibrating Tube densimeter, thus the apparent molar volumes were also reported for these cyanide solutions. From these heat capacity measurements and other relevant literature data the change in heat capacity in association to the ionization of HCN was derived. For the first time, such data were determined calorimetrically and reported. The present values were obtained from NaCN and KCN respectively, and are, -228.5 and -222.8 J K-1mo-1. The results are in very good agreement and provides a most reliable estimate of ∆Cp° for the ionization of HCN.
By establishing reliable equilibrium constants in this way, a better and accurate description of the chemistry of a given aqueous cyanide solution is achieved. These thermodynamic information obtained at high saline medium serve to develop more realistic models of such hydrometallurgical solutions in local processing industries.
30
Guilfoyle, Laurence Michael. "Quartz crystal microbalance analysis for cyanide and cyanide-degrading bacteria in gold process solutions." Thesis, Guilfoyle, Laurence Michael (1998) Quartz crystal microbalance analysis for cyanide and cyanide-degrading bacteria in gold process solutions. PhD thesis, Murdoch University, 1998. https://researchrepository.murdoch.edu.au/id/eprint/52707/.
Full textAbstract:
Cyanide is used by the gold mining industry to extract gold from ore. The accurate measurement of cyanide in process solutions and the removal of cyanide from wastes are two areas of significant concern for the gold mining industry.
Biological cyanide destruction has been used successfully to remove cyanide from process solutions and leachate from heap leach pads. The aim of this work was to investigate cyanide degrading bacteria from gold mines in Western Australia.
In order to measure the activity of cyanide degrading bacteria, a method was developed to determine cyanide in small sample sizes. An apparatus and method for measuring cyanide ion in gold process solutions is described. The potential of a solution to leach gold was measured by quartz crystal microbalance, flow injection analysis. Cyanide levels from 0.5 to 500 mg L-1 were determined every two minutes on sample sizes from 0.1 to 2.5 mL. Also described is an apparatus and method for rapid measurement of weak acid dissociable (WAD) cyanide. A gas permeable membrane cell was combined with quartz crystal microbalance, flow injection analysis to measure WAD cyanide. WAD cyanide levels from 0.5 to 500 mg L-1 were determined every two minutes on sample sizes from 1.0 to 2.5 mL.
These methods were developed to measure the activity of cyanide degrading bacteria in gold process solutions. A sub species of the bacterium, Bacillus pumilus, was isolated from a gold mine in Western Australia. It degraded cyanide to ammonia and formate. The bacterium was found to exhibit high levels of cyanide degrading activity (800 units L*1) which was maintained after storage at 4°C as the bacteria did not sporulate under these conditions. This bacterium could not degrade WAD cyanide and could not grow in the presence of cyanide above 10 mg L-1.
A mixed culture of bacteria was isolated from a second gold mine that could grow in the presence of cyanide and could degrade 150 mg L-1 of WAD cyanide to below 0.5 mg L-1 in leachate from dump leached ore. Column tests showed that the addition of nutrients alone could stimulate bacteria already present in the ore to degrade cyanide. The rate of cyanide destruction in the nutrient only column was approximately half the rate of the column to which bacteria had been added. The nutrient only treatment method could reduce treatment costs for the decommissioning of heap leach pads as no bioreactor would be required.
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Basile, Lacy Jamel. "Cyanide-degrading enzymes for bioremediation." Texas A&M University, 2008. http://hdl.handle.net/1969.1/86035.
Full textAbstract:
Cyanide-containing waste is an increasingly prevalent problem in today's
society. There are many applications that utilize cyanide, such as gold mining and
electroplating, and these processes produce cyanide waste with varying conditions.
Remediation of this waste is necessary to prevent contamination of soils and water.
While there are a variety of processes being used, bioremediation is potentially a more
cost effective alternative.
A variety of fungal species are known to degrade cyanide through the action of
cyanide hydratases, a specialized subset of nitrilases which hydrolyze cyanide to
formamide. Here I report on previously unknown and uncharacterized nitrilases from
Neurospora crassa, Gibberella zeae, and Aspergillus nidulans. Recombinant forms of
four cyanide hydratases from N. crassa, A. nidulans, G. zeae, and Gloeocercospora
sorghi were prepared after their genes were cloned with N-terminal hexahistidine
purification tags, expressed in Escherichia coli and purified using immobilized metal
affinity chromatography. These enzymes were compared according to their relative
specific activity, pH activity profiles, thermal stability, and ability to degrade cyanide in
the presence of high concentrations of copper and silver. Although all four were relatively similar, the N. crassa cyanide hydratase (CHT)
has the greatest thermal stability and widest pH range where activity remained above
50%. N. crassa also demonstrated the highest rate of cyanide degradation in the
presence of both metals tested. The CHT of A. nidulans and N. crassa have the highest
reaction rate of the four fungal nitrilases evaluated in this work.
These data help determine optimization conditions for the possible use of these
enzymes in the bioremediation of cyanide-containing waste. Similar to known plant
pathogenic fungi, in vivo expression of CHT in both N. crassa and A. nidulans were
induced by growth in the presence of KCN (potassium cyanide).
32
Ezzi, Mufaddal I. "Cyanide detoxification by soil microorganisms." Thesis, University of Surrey, 2001. http://epubs.surrey.ac.uk/842816/.
Full textAbstract:
Cyanides enter the environment through both natural and man-made sources. Natural sources include cyanogenesis by bacteria, fungi and plants. A number of cyanide catabolising microorganisms have also been reported in literature. This is the first reported instance of cyanide catabolism in Trichoderma harzianum. Four strains of T. harzianum, one of T. pseudokoningii were evaluated. An investigation was made into the occurrence and distribution of the cyanide catabolising enzymes. Three enzymes, cyanide hydratase, beta-cyanoalanine synthase and rhodanese, were studied. All the strains showed a high capacity to degrade cyanide via both the cyanide hydratase and rhodanese pathways, beta-cyanoalanine synthase activity, however, was not detected in any of the selected strains. In the studies on the kinetic characterization of the rhodanese enzyme, a broad pH optimum of 8.5 - 10.5 was obtained for all the strains and a broad temperature optimum of 35 - 55 °C was also observed. The KmCN and Vmax values ranged from 7-16 mM and from 0.069 - 0.093 betamoles. Min-1. mg protein-1, respectively, between the selected strains of Trichoderma. Strong evidence of cyanide biodegradation and co-metabolism emerged from studies with flask cultures where glucose was provided as a co-substrate. The rate of degradation of 2000 ppm CIST was enhanced almost three times in the presence of glucose. Plant microcosm studies carried out using pea and wheat seeds too gave further corroboration of the cyanide degrading and plant growth promotion capabilities of Trichoderma. Microcosms set-up with cyanide at 50 or 100 ppm CN, in the presence of Trichoderma, showed germination of both pea and wheat seeds. There was no seed germination in any of the controls in the absence of Trichoderma inoculation.
33
Lu, Jianming. "Copper electrowinning from cyanide solutions." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0015/NQ48655.pdf.
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Convine, Nicola Jane. "Stereoselective conjugate addition of cyanide." Thesis, Imperial College London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.424510.
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Molojwane, Emang Tsametse Emi. "Engineering cyanide-tolerant Arabidopsis thaliana." Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/19996.
Full textAbstract:
Cyanide is highly toxic as it inhibits respiration in aerobic organisms by binding to cytochrome c oxidase in the mitochondrial electron transport chain. Plants naturally produce cyanide from the hydrolysis of cyanogenic glycosides and as a by-product of ethylene biosynthesis. β-Cyanoalanine synthase prevents self-poisoning by combining endogenous cyanide with cysteine in the mitochondria to form β-cyanoalanine, which is further hydrolysed to asparagine, or aspartate and ammonia, by plant nitrilase 4 enzymes. β-Cyanoalanine synthase activity enables plants to detoxify limited concentrations of exogenous cyanide. However, phytotoxicity and death occur from exposure to relatively low concentrations of exogenous cyanide. In contrast, some microorganisms have a high capacity for cyanide detoxification due to a number of metabolic pathways including the degradation of cyanide to formate and ammonia; or formamide, by bacterial cyanidase (CynD) and fungal cyanide hydratase (CHT), respectively. Environmental contamination caused by failure to contain cyanide from anthropogenic sources is an important global problem. Hydrometallurgical gold mining utilises cyanide as a lixiviant due to the high affinity of cyanide for gold and the stability of the resulting cyanometallic complexes in aqueous solution, and thus is a significant source of cyanide contamination of soil and water. Biological treatment methods for cyanide, such as phytoremediation, could provide alternatives to the currently used chemical destruction techniques with their associated disadvantages. The use of phytoremediation would require plants to tolerate high concentrations of cyanide in soil. Two attempts have previously been made, with some success, to increase cyanide tolerance in Arabidopsis by genetic engineering: the first, by augmenting the β-cyanoalanine synthase pathway using a microbial nitrilase; and, the second, by introducing a microbial detoxification pathway targeted to the chloroplasts while overexpressing the endogenous enzyme which metabolises the product of the cyanide detoxification reaction. The aim of the current study was to determine whether Arabidopsis thaliana could co-opt the CynD and CHT genes from the cyanide-degrading Bacillus pumilus and Neurospora crassa to detoxify higher levels of cyanide using the encoded enzymes, and whether targeting CynD and CHT to the mitochondria would confer a greater enhancement of cyanide tolerance on plants compared to targeting to the cytoplasm.
36
Rehbein, Marcus. "Polymere Metallcyanide als Vorstufen für intermetallische Phasen und Mischoxide." [S.l.] : [s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=96310487X.
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Sidibe, Aissatou. "EFFECT OF ABIOTIC STRESSES AND CYANIDE TREATMENT ON THE CYANIDE ASSIMILATORY PATHWAY IN ARABIDOPSIS THALIANA." Available to subscribers only, 2008. http://proquest.umi.com/pqdweb?did=1674095021&sid=1&Fmt=2&clientId=1509&RQT=309&VName=PQD.
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Kunze, Nils. "Vorkommen, Speziesverteilung und Transportverhalten von Cyaniden im Grundwasser des Testfeldes Süd." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=970402481.
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Wei, YiQiu. "The chemistry of 2,3-unsaturated glycosyl cyanides." Scholarly Commons, 1991. https://scholarlycommons.pacific.edu/uop_etds/2225.
Full textAbstract:
Carbohydrate research remains one of the most exciting endeavors in the field of organic chemistry. The importance of carbohydrates needs little elaboration. Quite literally, without glucose, cellulose, and starch, the necessities of life such as food, clothing, and shelter would be missing. In our laboratory, we have for some time been interested in one particular class of carbohydrate derivatives - the aldohexopyranosyl cyanides.
40
Llamas-Rey, Estefania. "Redox-active cyanide-bridged dimanganese complexes." Thesis, University of Bristol, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390645.
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Onganusorn, Sriwipha. "Cyanide complexes as redox-active ligands." Thesis, University of Bristol, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.425135.
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Perera, Weeratunge Nimal. "Hydrolysis and cyanide speciation of some heavy metals relevant to the fate of cyanide in the environment." Thesis, Perera, Weeratunge Nimal (2001) Hydrolysis and cyanide speciation of some heavy metals relevant to the fate of cyanide in the environment. PhD thesis, Murdoch University, 2001. https://researchrepository.murdoch.edu.au/id/eprint/5300/.
Full textAbstract:
Quantitative understanding of the fate of cyanide in the environment and its role in industrial processes requires quantitative characterisation of metal ion–cyanide complex formation and also the corresponding metal ion hydrolysis reactions that frequently compete with them. This thesis presents quantitative data for complex formation constants obtained using a range of techniques for a number of metal ion–hydroxide and metal ion–cyanide systems of environmental and hydrometallurgical importance that have been found difficult to study in the past. A specially–constructed combined spectrophotometric /potentiometric cell has enabled a variety of systems to be studied by UV–Visible spectroscopy at very low metal ion concentrations. This has circumvented problems associated with precipitation and/or polynuclear metal complex formation, which frequently predominate in these systems at higher concentrations.
Using this approach it has been possible to determine the formation constants and spectra of the mononuclear hydroxide complexes of Pb(II), Cu(II), Fe(III), Ag(I) and for the cyanide complexes of Pb(II), Ag(I), Ni(II) and Fe(III). It has also been possible to estimate the solubility products of Pb(CN)2(s), AgOH(s), AgCN(s) and NaFeFe(CN)6(s). For some of these species (namely, Pb(OH)42–, the higher order hydroxo–complexes of Cu(II) and Fe(III), Pb(CN)+, and the lower cyano–complexes of Fe(III)), the present results are the first quantitative estimates of their formation constants. These complexes have long been assumed to exist on theoretical grounds but have proven difficult to quantify experimentally. The main reasons for this difficulty are the sparing solubility of the neutral hydroxides and /or cyanides and the tendency of CN– to form either very weak or extremely strong complexes.
Where possible, attempts were made to confirm the spectrophotometric results using other techniques such as polarography, NMR spectroscopy (for Pb(II)), Raman spectroscopy and, for Cu(II), ESR spectroscopy. However, although these techniques were sometimes able to provide useful insights into the nature of the species formed, in general they were not sufficiently sensitive, or suffered from other constraints that meant that they yielded little quantitative information.
The formation constants measured in this work were combined with literature data to model the chemical behaviour of hypothetical cyanide–infiltrated soil. This modelling indicates that under typical contaminated soil conditions (i.e. soil containing Fe(OH)3(s) and [CN–] = 0.1mM), cyanide will be present mainly as the various forms of Prussian blue. However, strong competition between cyanide and hydroxide ions for Fe(III), points to possible conditions for the chemical degradation of the Prussian blue.
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Mpongwana, Ncumisa. "Nitrification and aerobic denitrification in cyanide-containing wastewater." Thesis, Cape Peninsula University of Technology, 2016. http://hdl.handle.net/20.500.11838/2371.
Full textAbstract:
Thesis (MTech (Chemical Engineering))--Cape Peninsula University of Technology, 2016.Anthropogenic activities that utilise cyanide in various chemical forms have resulted in the disposal of cyanide-contaminated effluents into drainage systems that ultimately reach wastewater treatment plants (WWTP), without prior treatment. Cyanides (CN) and soluble salts could potentially inhibit biological processes in WWTP, which are responsible for the removal of contaminants from incoming wastewaters. The removal of nitrogenous compounds from such waters in processes such as nitrification and denitrification is among the core biological processes used to treat wastewaters in WWTP. Electroplating and mining industries are among the perpetrators of cyanide contamination of WWTP. The presence of these hazardous contaminants results in the alteration of metabolic functions of the microbial populations that are utilised in WWTP, thus rendering the wastewater treatment process ineffective. In this study, bacterial isolates that were able to carry out nitrification and aerobic denitrification under high salinity cyanogenic conditions were isolated from poultry slaughterhouse effluent. These strains were referred to as I, H and G. The isolated bacterial species were found to be able to oxidise ammonium nitrogen (NH4-N) in the presence of free cyanide (CN-) under halophilic conditions. Isolates I, H and G were identified using the 16S rDNA gene and were identified to be Enterobacter sp., Yersinia sp. and Serratia sp., respectively. Furthermore, Response Surface Methodology was used to optimise the physicochemical conditions suitable for the proliferation of the isolates for free-cyanide degradation, nitrification and aerobic denitrification.
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Choo, Bee Khim. "Mechanisms of cyanogen reduction during fermentation of cassava." Thesis, University of Nottingham, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298989.
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Wood, Andrew John. "Mixed-metal complexes incorporating redox-active cyanomanganese ligands." Thesis, University of Bristol, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311404.
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Hamberg, Roger. "Characterization and solidification of arsenic-rich cyanided tailings." Licentiate thesis, Luleå tekniska universitet, Geovetenskap och miljöteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-17804.
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Information on the occurrence of As species and iron sulphide minerals in tailings is essential for predicting therelease of As over extended period of time. Tailings originating from a goldmine in northern Sweden with low content of trace elements except for As were used for this purpose. The dominating sulphides were pyrrhotite and arsenopyrite. The samples used in the study were post-cyanided, tailings slurries treated with Fe2(SO4)3 and H2O2 to form arsenates and Fe-hydrates for effective As-immobilization. Speciation of the As in ore and tailings samples revealed that mining processes have dissolved the majority of the arsenopyrite in the ore, causing secondary As phases to co-precipitate with newly formed Fe-hydrates. A minor part of the As retained in the tailings was assumed to be As (III)-species. Weathering cell tests (WCT) involving 32 weekly cycles of wetting and air exposure were conducted to assess the effect of weathering on the stability of As in the tailings. As-bearing Fe-hydrates remained intact during the early stages of the WCT; the low release of As during this period was probably due to the dissolution of solubleAs(III)-phases. During the later stages of the WCT, the release of As, Fe and S increased due to pyrrhotite oxidation and the destabilization of As-bearing Fe-hydrates. The majority of the originally present As was still associated with the tailings by the end of the test, but additional pyrrhotite oxidation with the pH falling to >3 could further destabilize these As-bearing Fe-hydrates. In the second part of the study,cyanided tailings were converted into a monolith by using a method called cemented paste backfill (CPB). Two mixtures of CPB were tested; CE with 1 wt. % of cement and CE-FA consisting 2 weight (wt.) % of cement together with 1 wt. % of biofuel fly ash. The stability of As in CPB-masses andun-amended tailings were evaluated using tank leaching tests (TLT) and WCT: s. TheTLT results showed that the CPB mixtures were not suitable for use inunderground backfilling because the As content of the CPB leachates increasedcontinuously over the course of the tests. The proportion of binders inCPB-materials is usually 3-7% because such loadings are required to create amonolithic mass that physically and chemically stabilizes arsenic species intailings. The addition of small quantities of binders in CE and CE-FA maytherefore have been insufficient to ensure that the monoliths were highly saturated, which is required to prevent the transport of oxygen and water through the CPB material. In the WCT, crushed CPB materials were used and the addition of binders caused only a minor increase in the leaching of As relative to that seen with unmodified tailings. The addition of binders has re-located a minor proportion of As in As-bearing Fe-hydrates into less acid-tolerant species. During the later stages of the WCTs, the CPB mixtures were treated with acid in order to consume the buffering minerals and simulate the formation of acid mine drainage (AMD). When acid was added to crushed CPB-materials, As-release increased due to the dissolution of Fe-hydrates. The addition of binders into tailings could pose more resistance to sulphide oxidation, which in turn means that the stability of As-bearing Fe-hydrates could be prolonged on long term. Results from the WCT suggested that the addition of low proportions of binders could have a positive effect on As-leaching in a long term perspective. A relatively new method called “Surfacepaste disposal” (SPD), where mixtures of low proportions of binders and tailings is placed as a cover on the un-amended tailings has shown promising results in terms of decreasing As-leaching and the generation of AMD. Future research will, therefore, focus on the stability of As in SPD-applications.Godkänd; 2014; 20141015 (rogham); Nedanstående person kommer att hålla licentiatseminarium för avläggande av teknologie licentiatexamen. Namn: Roger Hamberg Ämne: Tillämpad geologi/Applied Geology Uppsats: Characterization and Solidification of Arsenic-rich Cyanided Tailings Examinator: Biträdande professor Lena Alakangas, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet Diskutant: Fil. lic / Enhetschef Bergteknik Lena Sultan, Ramboll Sverige AB Tid: Torsdag den 4 december 2014 kl 13.00 Plats: E246, Luleå tekniska universitet
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Marelli, Elena. "New chemistry and physics from transition-metal cyanides." Thesis, University of Reading, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.627647.
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Sevim, Ilhan. "Reactions Of Diethylaluminum Cyanide With Acyl Phosphonates." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/3/12611557/index.pdf.
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This thesis includes reaction of diethylaluminum cyanide with acyl phosphonates. Cyanohidrin O-phosphates are synthesized from easily available acyl phosphonates and diethylaluminum cyanide. Synthesis of cross-benzoin product of acyl phosphonate, α
-hydroxy phosphonate and tertiary carbinol are synthesized from the reaction of diethylaluminum cyanide with acyl phosphonates, representatively. Asymmetric syntheses of cyanohydrin and benzoin type reaction of acyl phoshonate are also investigated representatively.
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Onabolu, Adeyinka. "Cassava processing, consumption and dietary cyanide exposure /." Stockholm, 2001. http://diss.kib.ki.se/2001/91-628-4894-1/.
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Rozario, Hoimonti Immaculata. "Spectroscopic study of acetylene and hydrogen cyanide." Thesis, Lethbridge, Alta. : University of Lethbridge, Dept. of Physics and Astronomy, c2012, 2012. http://hdl.handle.net/10133/3415.
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High-resolution molecular spectroscopy has been used to study acetylene line parameters and emission spectra of hydrogen cyanide. All acetylene spectra were recorded in our laboratory at the University of Lethbridge using a 3-channel tuneable diode laser spectrometer. N2-broadened line widths and N2-pressure induced line shifts have been measured for transitions in the v1+v3 band of acetylene at seven temperatures in the range 213–333K to obtain the temperature dependences of broadening and shift coefficients. The Voigt and hard-collision line profile models were used to retrieve the line parameters.
The line-broadening and line-shift coefficients as well as their temperature-dependent parameters have been also evaluated theoretically, in the frame work of a semi-classical approach based on an exponential representation of the scattering operator, an intermolecular potential composed of electrostatic quadrupole–quadrupole and pairwise atom–atom interactions as well as on exact trajectories driven by an effective isotropic potential. The experimental results for both N2-broadening and shifting show good agreement with the theoretical results.
We have studied the line intensities of the 1νl20←0νl20 band system from the HCN emission spectrum. The infrared emission spectrum of H12C14N was measured at the Justus-Liebig University, Giessen, Germany. The emission spectrum was analyzed with the spectrum analysis software Symath running using Mathematica as a platform. This approach allowed us to retrieve information on band intensity parameters.viii, 112 leaves : ill. ; 29 cm