Candida tropicalis yeast is a microorganism that possesses high tolerance for phenol and strong phenol degrading activity. This yeast is capable of utilizing phenol as the sole source of carbon and energy without formation of any secondary waste product. Catechol-1,2- dioxygenase was isolated from cytosolic fraction of this yeast by the procedure consisting of chromatography on DEAE-Sepharose and gel permeation chromatography on Sephadex G- 100. The catechol-1,2-dioxygenase was purified to homogeneity. The enzyme activity was followed by HPLC (catechol consumption and/or cis,cis-muconic acid formation). The activity profiles at different temperatures showed temperature optimum of 30řC. Kinetic characterizations were studying in different values of pH. The values of Km and Vmax of 0,52 mM and 17,2 nM/min for consumption of catechol, respectively, and 0,34 mM and 12,6 nM/min for formation of cis,cis-muconic acid, respectively, were found at optimum pH of the reaction, pH 7,6.

In the recent years, many research articles focused on endocrine disrupting compounds in the environment. Some of these compounds are listed in a group named brominated flame retardants. However, only few articles investigated endocrine activity of several "new" brominated flame retardants. These chemicals such as 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE) or bis(2-ethylhexyl) tetrabromophthalate (TBPH) are newly used due to ban of some previously most produced brominated flame retardant mixes. In this study, we used two recombinant yeast screens to measure estrogenic, androgenic, antiestrognic and antiandrogenic activities of some alternative brominated flame retardants. We also used ligninolytic fungi to investigate biodegradation of these compounds. Our results suggest, that 2,4,6-tribromophenol (TBP) may be a new environmental endocrine disruptor. This substance showed antiestrogenic and antiandrogenic activity in our tests. 1,2-bis(2,4,6- tribromophenoxy)ethane (BTBPE) had certain antagonistic activity too. In the biodegradation experiment, only three compounds showed significant degradation during the test period. No biodegradation have been observed for other compounds. In this study, we applied gas chromatography with mass spectrometry to analyze these "new" flame retardants. Method for gas...

Sulfonamides are antibiotics that are frequently used both in human and veterinary medicine. The combinations of abundant use of these antibiotics and their natural resistance to decay leads often to long term persistence in the environment. This accumulation, especially in living organisms, may lead to subsequent toxicosis. Also, presence of these antibiotic in nature poses problems with regard to the spread of genes for antibiotic resistance between potential pathogens. These facts led to an increase interest in studying the sulfonamide biodegradation and subsequent sulfonamide removal from the environment. In this work it was possible to isolate and characterize the microorganism Acinetobacter sp. strain 49. This microorganism was able to biodegrade under right conditions sulfamethoxazole with 80 % efficiency. Sulfamethoxazole is one of the most commonly found sulfonamide in the nature.

Antibiotic effectiveness, forests, and climate stability are three of the most endangered public and common goods of the twenty-first century. All three are threatened by individuals ignoring the negative consequences of their actions on society: spreading antibiotic resistance, increasing forest degradation, and accelerating climate change. All these effects are likely to have long-lasting impacts on global health and economic development. This dissertation seeks to understand these human–environment interactions better while evaluating policies promoting sustainable behaviors or improving economic resilience. The first chapter considers the trade-off in prescribing antibiotics: they cure bacterial infections, but they spur antibiotic resistance. I estimate two essential parameters to calibrate any model of antibiotic resistance: the causal impact of prescriptions on antibiotic resistance and the elasticity of demand for an antibiotic. After developing and calibrating a dynamic bio-economic model of the issue, I show that it can be welfare-improving to increase out-of-pocket expenditure on antibiotics used to tackle spreading infections. The second chapter calculates the geographical distribution of people at risk of falling into poverty in the aftermath of droughts and floods in Malawi. Its methods can be expanded to identify the beneficiaries of scalable social safety nets or ex-ante climate insurance. Such programs would increase the resilience of the poor to climate change. The third chapter investigates the potential double dividend of internal migration in terms of poverty alleviation and forest regeneration in Central India. It relies on an innovative index of forest degradation created from high-resolution remote sensing imagery and unique data on internal migration and forest pressure based on a survey of 5,000 households.

The biodegradation process of some types of polymers occurs due to many different factors including their morphology, structure and chemical composition. Although this is a complicated process, most of its important stages like the diffusion of monomers and the hydrolysis reactions have been modeled phenomenologically through reaction-diffusion equations, where the properties of the polymers were encompassed. Using a simplified reaction-diffusion model for the biodegradation of polymers, in this contribution we study the possible effects of the curvature of the system’s geometry in the degradation process, which is characterized by the interaction of the corresponding reaction rate and the diffusion coefficient. To illustrate the problem of diffusion on a curved surface we consider the surface of a cylinder and of the so-called Gaussian bump. We show how the degradation process is affected by the curvature of the system for the simplified model.

Thesis (DTech (Chemistry))--Cape Peninsula University of Technology, 2016. / The use of ozone as an advanced oxidation process is gathering wide spread attention with the major limitation to its application being its cost of operation and design considerations. While the general approach of most researches is to buttress the already known fact of the efficacy of the process, little attention is given to studying the by-products of ozone reactions with organics. The aims of this study were to investigate the efficacy of the ozonation process for removing recalcitrant phenolics: phenol, 2-chlorophenol (2CP), 4-chlorophenol (4CP) and 2,4-dichloropheno (2,4DCP) from aqueous medium with a view of understanding various reaction pathways of the process and identifying possible intermediates and residual compounds using liquid chromatography-mass spectrometry (LC-MS). The choice of the selected chlorophenols would also elucidate the role of the positioning of the chlorine atoms in determining reaction rates, pathways and subsequent mechanisms and by-products. Sequel to this, oxy-hydroxy iron in β-phase (β-FeOOH, akaganite) and various β-FeOOH bonded composites on support metal oxides (Al2O3, NiO and TiO2) were prepared via hetero-junction joining, and explored as a possible promoter to improve the efficiency of the ozonation process. Apparent first order reaction rates constants of tested phenolics was in the order 2,4-DCP > 2-CP > Phenol > 4-CP, irrespective of the tested pH. The individual rates however increased with increasing pH. The position 4 chlorine atom was found to be least susceptible to hydroxylative dechlorination. Catechol intermediate and pathway was identified as the major degradation pathway for phenol and 2-CP, while 4-chlorocatechol pathways were more important for 4-CP and 2,4-DCP. The formation of polymeric dimers and trimers by all compounds was pronounced at alkaline pH. Heterogeneous catalytic ozonation using β-FeOOH reduced ozonation time for 4-CP by 32%. Mechanism for β-FeOOH/ozone catalysis showed that the catalyst suffered reductive dissolution in acidic pH and the kinetics of 4-CP removal using the catalyst was best described using a two stage kinetic model. The first stage was attributed to heterogeneous catalysis of ozone breakdown on β-FeOOH surface generating faster reacting radicals, while the second stage was due to homogeneous catalysis by reduced Fe2+ ions in solution. β-FeOOH stabilized on NiO at a 5% ratio exhibited superior catalytic property compared to the other tested composites. Characterization by high-resolution transmission electron microscopy (HRTEM) affirmed a β-FeOOH-NiO bonded interfaced composite which was stable as a iv catalyst over four (4) recycle runs. The mechanism of operation of the composite was via an increased ozone breakdown to radicals as monitored via photoluminescence experiments. The composite material produced satisfactory results when tested on real wastewater samples. Results from this study contribute to the current understanding on reaction mechanisms for ozone with phenols and chlorophenols, for the first time monitoring time captured intermediates via liquid chromatography-mass spectrometric method, which preserves the integrity of reaction intermediates. Also this study proposes heterogeneous catalysts; β-FeOOH and β-FeOOH bonded composites as possible improvements for simple ozone based water purification systems.

Ces travaux ont consisté à développer un procédé de traitement biologique des eaux contaminées en produits phytosanitaires (PF) issues du lavage des matériels de pulvérisation de PF. Ce procédé s’appuie surl’inoculation d’une culture bactérienne mixte sélectionnée et d’un matériau sorbant constitué de rafles de maïs broyées.Tout d’abord, un mélange modèle de PF,constitué de 6 herbicides, 3 fongicides et 1 insecticide, a été créé. Après avoir mis au point la production de l’inoculum en présence de ce mélange et étudié les propriétés sorbantes des rafles de maïs, les paramètres de traitement ont été définis à petite échelle de laboratoire et validés en réacteur.Finalement, le procédé développé est un traitement en réacteur batch séquentiel de 28 jours qui permet de réduire de plus de 50 % la masse initiale des PF du mélange modèle. Malgré la réduction des teneurs en PF, la phytotoxicité due aux résidus d’herbicides des effluents traités est encore trop élévée et ne permet pas de valider l’épandage sur un lit planté de roseaux comme post-traitement de la fraction liquide. / Aim of this work was to treat effluentsobtained from rinsing pesticide (PF) spraying equipments by developing biological treatment process into bioreactor with selected mixed bacterial culture and adsorption support consisting of crushed corn cobs. First, a model PF mixture was designed to represent agriculturaleffluents at watershed scale. This mixture was composed by 6 herbicides, 3 fungicides and 1 insecticide. Then, inoculum production under PF pressure was developed and sorption properties of corn cobswere investigated. Process parameters were defined at small-scale laboratory and validated into bioreactors. Thus, developed processwas a28 days sequential batch reactortreatment, which reduced more than 50% of molecules weight of model mixture.Despite of this process significantely reduced treated effluents PF contents, remaining phytotoxicity due to herbicide residues failed validation of their post-treatment on a bed planted with reeds.

The overall goal of this work was to investigate microbial activity leading to the anaerobic degradation of polycyclic aromatic hydrocarbons and an organophilic clay sediment cap used at a creosote-contaminated Superfund site. To determine whether or not PAHs were being degraded under anaerobic conditions in situ, groundwater and sediment porewater samples were analyzed for metabolic biomarkers, or metabolites, formed in the anaerobic degradation of naphthalene (a low-molecular weight PAH). In addition, a groundwater push-pull method was developed to evaluate whether the transformation of deuterated naphthalene to a deuterated metabolite could be monitored in situ and if conservative rates of transformation can be defined using this method. Metabolites of anaerobic naphthalene degradation were detected in all samples that also contained significant levels of naphthalene. Anaerobic degradation of naphthalene appears to be widespread in the upland contaminated aquifer, as well as within the adjacent river sediments. A zero-order rate of transformation of naphthalene-D₈ to naphthoic acid-D₇was calculated as 31 nM·d-¹. This study is the first reported use of deuterated naphthalene to provide both conclusive evidence of the in situ production of breakdown metabolites and an in situ rate of transformation. Methane ebullition was observed in areas of the sediment cap footprint associated with organophilic clay that was used a reactive capping material to sequester mobile non-aqueous phase liquid (NAPL) at the site. Anaerobic slurry incubations were constructed using sediment core samples to quantify the contribution of the native sediment and the different layers of capping material (sand and organophilic clay) to the overall methane production. Substrate addition experiments using fresh, unused organophilic clay, as well as measured changes in total carbon in organophilic clay over time supported the hypothesis that microbes can use organophilic clay as a carbon source. Quantitative PCR (qPCR) directed at the mcrA gene enumerated methanogens in field samples and incubations of native sediment and capping materials. Denaturing gradient gel electrophoresis (DGGE) was also performed on DNA extracted from these samples to identify some of the predominant microorganisms within the sediment cap footprint. The organophilic clay incubations produced up to 1500 times more methane than the native sediment and sand cap incubations. The organophilic clay field sample contained the greatest number of methanogens and the native sediment contained the least. However, the native sediment incubations had greater numbers of methanogens compared to their respective field sample and comparable numbers to the organophilic clay incubation. An increase in methane production was observed with the addition of fresh, unused organophilic clay to the already active organophilic clay incubations indicating that organophilic clay stimulates methanogenesis. In addition, organophilic clay retrieved from the field lost about 10% of its total carbon over a 300-day incubation period suggesting that some component of organophilic clay may be converted to methane. DGGE results revealed that some of the predominant groups within the native sediment and sediment cap were Bacteriodetes, Firmicutes, Chloroflexi, and Deltaproteobacteria. An organism 98% similar to Syntrophus sp. was identified in the organophilic clay suggesting this organism may be working in concert with methanogens to convert the organic component of organophilic clay ultimately to methane. The capacity of organophilic clay to sequester organic contaminants will likely change over time as the organic component is removed from the clay. This, in turn, affects the use of this material as a long-term remedial strategy in reduced, contaminated environments.

Cysteamine (CA), which is an aminothiol drug medically known as Cystagon® was studied in this thesis. Cysteamine was reacted with a binary toxin called peroxynitrite (PN) which is assembled spontaneously whenever nitric oxide and superoxide are produced together and the decomposition of peroxyinitrite was monitored. PN was able to nitrosate CA in highly acidic medium and excess CA to form S-nitrosocysteamine (CANO) in a 1:1 with the formation of one mole of CANO from one mole of ONOOH. In excess oxidant (PN) the following 1:2 stoichiometric ratio was obtained; ONOO- + 2CA → CA-CA + NO2- + H2O . In alkali medium the oxidation of CA went through a series of stages from sulfenic acid, sulfinic acid and then sulfonic acid which was followed by the cleavage of the C-S bond to form a reducing sulfur leaving group, which is easily oxidized to sulfate. The nitrosation reaction was first order in peroxynitrite, thus implicating it as a nitrosating agent in highly acidic pH conditions. Acid catalyzes nitrosation reaction, whitst nitrate catalyzed and increased the amount of CANO product, This means that the nitrosonium cation, NO+ which is produced from the protonation of nitrous acid(in situ) as also contributing to the nitrosation of CA species in highly acidic environments. The acid catalysis at constant peroxynitrite concentrations suggests that the protonated peroxynitrous acid nitrosates at a much higher rate than the peroxynitrite and peroxynitrous acid. Bimolecular rate constants for the nitrosation of CA, was deduced to be 10.23 M-1 s-1. A linear correlation was obtained between the initial rate constants and the pH. The oxidation of CA was modeled by a simple reaction scheme containing 12 reactions.

京都大学 / 0048 / 新制・課程博士 / 博士(地球環境学) / 甲第17802号 / 地環博第109号 / 新制||地環||22(附属図書館) / 30609 / 京都大学大学院地球環境学舎地球環境学専攻 / (主査)教授 勝見 武, 教授 三村 衛, 准教授 乾 徹 / 学位規則第4条第1項該当 / Doctor of Global Environmental Studies / Kyoto University / DFAM