National Repository of Grey Literature 78 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Stress responses in Rhodococcus strains
Křenková, Lucie ; Pátek, Miroslav (advisor) ; Cajthaml, Tomáš (referee)
Throughout the evolution, bacteria developed ingenious mechanisms which help them survive and grow in harsh conditions, where extreme temperatures, pH, changing water and osmotic activity occurs. Rhodococcus sp. cope with these conditions so efficiently they are able to grow in the presence of toxic compounds. Large genome of Rhodococcus sp. consists of a great amount of genes involved in a broad spectre of catabolic pathways. To use these skills in biotechnology, it is necessary to know stress response mechanisms well. In response to the changing environment Rhodococcus sp. use transcriptional regulators, two-component system and RNA polymerase sigma factors to tune the expression profiles of the genes. The upregulation of chaperons, chaperonins and proteases is the main pattern followed in most of the stress responses. Vast majority of stress responses is complex and groups of genes to react on them interfere too. Thus, it is very difficult to interpret the data of these studies. However, the great importance of understanding these mechanisms is unquestionable. Key words: stress response, bacteria, Rhodococcus, biotechnology, degradation, toxic compounds, sigma factor
Toxicity of perfluorinated hydrocarbons
Leifertová, Karolína ; Cajthaml, Tomáš (advisor) ; Innemanová, Petra (referee)
Perfluorinated hydrocarbons are manmade chemicals used to make fluoropolymer coatings and products resistant to stains, oil, heat and water. Perfluorinated compounds such as perfluorooctane acid (PFOA) perfluorooctane sulfonate (PFOS) have been recognized as emerging environmental pollutants due to their persistance and ubiquity in the environment, biota and also humans. This paper focuses on toxicity of perfluorinated hydrocarbons, mainly PFOS and PFOA. A special attention is given to mechanism of toxicity of perfluorinated compounds, which have not yet been fully elucidated. Further studies should be performed to reveal the environmental risk assessment and mechanism of toxicity of perfluorinated compounds.
Utilization of tissue cultures for toxicology of the environment.
Polanská, Daniela ; Cajthaml, Tomáš (advisor) ; Klusoň, Petr (referee)
5 Abstract Five substances from the group of so-called personal care products, known for their low degradability and regular environmental detection, were tested for toxicity using two fish tissue lines (RTgill-W1 a RTG-2) isolated from rainbow trout (Oncorhynchus miykiss). The tested substances were hexadecylpyridinium chloride (HDP), chlorhexidine (CHX), octenidine (OCT), thymol (THM) and triclosan (TCS). A cell viability assay was performed with each of these compounds using Alamar Blue ™ (AB), 5-carboxyfluorescein diacetate acetoxymethyl ester (CFDA-AM) and neutral red (NR) protocols. The results were used to construct dose-response curves along with an EC50 value for each of these substances. The EC50 values ranged from 0,51 (HDP) to 33,75 µg.ml-1 (THM) for RTgill-W1 and from 0,31 (HDP) to 33,37 µg.ml-1 (THM) for RTG-2. The theoretical LC50 estimation was calculated according to Tanneberger et al. (2013). For all substances, cytochrome P450 1A activity was monitored using 7-ethoxyresorufin-o-deethylase (EROD), four out of five tested chemicals were statistically positive for EROD, the highest EROD response was observed for the most toxic compound - HDP. Only TCS did not show statistically significant cytochrome P450 1A activity. In addition, oxidative stress was measured with the fluorescent dye...
Composting of materials contaminated by micropollutants
Kočí, Petra ; Cajthaml, Tomáš (advisor) ; Innemanová, Petra (referee)
Micropollutants are compounds of anthropogenic origin, detected at concentrations of ng·g-1 - mg·g-1 in the environment. Micropollutants are synthetic or natural compounds. Micropollutants are released into the environment due to various human activities. Despite low concentrations in the environment, they represent a real threat to organisms, because of their specific biological effects. Sewage sludge is used in agriculture due to its hight nutritious content. Via using sludge in agriculture, contained micropollutants can be released to environment. Composting is a cheap bioremediation method, used from 80's of the last century. This diploma thesis is focused on composting of sewage sludge, contamined with micropollutants. High degradation rate was observed in artificially contaminated sludge, mainly with endocrine disruptors (up to 100 %). Lower degradation rate was observed in sewage sludge from a pharmaceutical plant, some of the compounds were not degraded at all.
Fluorinated micropollutants in the environment
Hatasová, Nicolette ; Cajthaml, Tomáš (advisor) ; Klusoň, Petr (referee)
Perfluorinated compounds (PFCs) are considered as persistent organic pollutants. Their extensive use in various products leads to increase of their occurence in surface and ground water, soil, air and, generally, in the global ecosystem. In this diploma thesis, method for detection and quantification of 19 perfluorinated compounds was developed. This method was used for analysis of real drinking water and sewage sludge samples from Czech Republic. It is based on pre-extraction step and consecutive liquid chromatography with mass spectrometry, using negative chemical ionization (LC-MS). We developed a method for analysis of water samples, using solid-phase extraction (SPE). Using this method, concentrations of PFCs in 8 samples of drinking water from Czech Republic were evaluated. Total concentration of analyzed PFCs was 4 - 23 ng/L. Processing of sewage sludge samples using accelerated solvent extraction (ASE) showed matrix effect, which influenced ionization and led to false positive/negative results. For supression of the matrix compounds, we used SPE Envi-Carb columns. Using this optimised method, 23 sewage sludge samples from different locations in Czech Republic were analyzed. The most represented PFC in the environment, perfluoroctane sulfonate (PFOS), was detected in concentrations 5 - 386...
Toxicity and environmental fate of nanoscale zerovalent iron
Semerád, Jaroslav ; Cajthaml, Tomáš (advisor) ; Uhlík, Ondřej (referee) ; Kočí, Vladimír (referee)
Nowadays, nanoscale zerovalent iron (nZVI) is a nanomaterial commonly used in remediation practice. Although worldwide applications of nZVI have shown its effectiveness in degradation and immobilization of a wide range of organic and inorganic pollutants, potential negative effects of nZVI on exposed organisms have not been sufficiently explored. To avoid possible environmental risks, understanding of the mechanism of nZVI toxicity and its overall effects on microbial populations indigenous to remediation sites is needed. The presented thesis summarizes current knowledge of nZVI toxicity, and, moreover, deals with the development and application of a new test for in vitro evaluation of acute toxicity caused by newly developed nZVI-based materials. Additionally, in this thesis, the risk associated with changes in the toxicity of the aforementioned materials during the aging process was examined. In the last part, the effect of several nZVI-based materials on microbial communities of a real contaminated soil was monitored and evaluated using artificial microcosms. In addition, in this part, the potential of nZVI and its derived materials in combination with a biostimulation step during nanobioremediation is outlined.
Separation of microplastics from sewage sludge using heavy liquids
Pospíchalová, Eliška ; Innemanová, Petra (advisor) ; Cajthaml, Tomáš (referee)
This bachelor thesis is focused on microplastics in sewage sludge. Microplastics are currently often discussed topic, but their occurrence in sewage sludge isn't still sufficiently researched. The main source of microplastics in sewage sludge is waste water. Microplastics are accumulating in sewage sludge during wastewater treatment and enter terrestrial ecosystems with multiple times higher concentration in comparison to freshwaters as a result of their use in agriculture or in restoration. In the year of 2017 sewage sludge was in Czech Republic further processed by direct land application within agriculture and restoration of 42 %, compostation of 34 %, other uses of 14 %, landfilling of 7 % and incineration of 3 %. The use of sewage sludge in agriculture demonstrates significance of microplastics issue. The tested samples were sampled from five anonymous wastewater treatment plants in Czech Republic. The samples were investigated for applicability of methodology of separation microplastics with oxidation of natural organic matter by Fe2+ + 30 % H2O2 and flotation in saline solution of 5 M NaCl. Following identification of microplastics was carried out in optical microscope with magnification of 40x. For precise optical detection of microplastics the samples were dyed with rose bengal. The...
Using a modified biocharge to capture ammonia from the exhaust air
Kozlíková, Nikola ; Innemanová, Petra (advisor) ; Cajthaml, Tomáš (referee)
In my work I have dealt with the comparison of different types of biochar based solid materials, which could serve as a filling for ammonia capture filters. Three samples of biochar prepared from anaerobically stabilized sewage sludge were used to test the most suitable material at temperatures of 200 ř C, 400 ř C and 600 ř C, 3 samples of biochar prepared from oak wood at temperatures of 260 ř C, 400 ř C and 600 ř C, 2 samples of biochar prepared from a mixture of sewage sludge and wood chips pre-dried in a pilot scale biological drying plant, dried anaerobically stabilized sewage sludge and charcoal. The materials were impregnated with 50% sulfuric acid solution. They were then exposed to ammonia vapors for the time needed to complete the reaction on the surface of the impregnated material. Due to the chemical reaction, ammonium sulfate is produced, which can be used as a fertilizer in agriculture. It is known that the addition of biochar has a positive effect on the soil. In the case of a combination of biochar and ammonium sulphate, this may be an interesting soil additive. It could be an alternative to so-called scrubbers, where ammonia is trapped by bubbling dilute sulfuric acid. Transportation and application of the ammonium sulphate solution thus formed is not economically advantageous. To...
Utilization of phospholipid fatty acids analysis for biodrying study
Stránská, Štěpánka ; Cajthaml, Tomáš (advisor) ; Innemanová, Petra (referee)
The aim of this thesis is the utilization of phospholipid fatty acids (PLFA) analysis to determine groups of microorganisms present during the biodrying of sewage sludge and their description in relation to the temperature regime of the biodrying. Four experimental cycles A, B, C, D were followed. Cycles A, B and C, D differred from each other in the sewage sludge collected from two waste water treatment plants. The cycles A, B, C and D were each performed in two reactors with different aeration regimes to compare the mesophilic (max. temperature ±50 řC) and thermophilic (max. temperature ±70 řC) regimes of biodrying. PLFA analysis was used to determine the microbial groups. Concentrations of individual PLFA were subjected to principal component analysis (PCA). The total PLFA concentration corresponding to total microbial biomass was decreasing during both temperature regimes of cycles B, C, D, while the total PLFA concentration increased towards the end of both temperature regimes of cycle A. The total PLFA concentration reached statistically higher values at the end of the mesophilic regime of cycles B, C and D. The development of fungi to bacteria ratio showed that fungi applied more with the progression of both temperature regimes of cycles A, B and the thermophilic regime of cycle C. Based on...
Endocrine disruptors in consumer goods
Pařízková, Alžběta ; Šuta, Miroslav (advisor) ; Cajthaml, Tomáš (referee)
The Thesis focuses on the group of specific organic compounds with a potential risk of their endocrine disruptive effect, and appearing as UV filters in various cosmetic products. An extended list of such products was created on the basis of search in drugstores, pharmacies and perfume shops. The products were further grouped as cosmetics for adults, children, and those declared as bio products. The source data collection counted 156 individual products, with origin in 40 drugstores, 20 pharmacies, and 10 perfume shops. The data collection sites were distributed in big cities, their suburb parts, shopping parks, and small towns on many places in the Czech Republic. The products were mostly sun protection creams, oils and emulsions, body creams and emulsions, lips balsams, and hair cosmetics. In these items an occurrence of 7 organic compounds (suspected endocrine disruptors) from the SIN List, used as parts of UV filters, was followed. The compounds of interest were: ethylhexyl methoxycinnamate; benzophenone-1, benzophenone-2, benzophenone-3; 4,4-dihydroxyphenone; 4-methylbenzylidene camphor; 3-benzylidene camphor. Alternative names, product brand names, chemical structures, CAS numbers etc. were also collected from various sources. Of this group only ethylhexyl methoxycinnamate and benzophenone-3...

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