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Study of biodegradation of poly(hydroxy alkanoates).
Wurstová, Agáta ; Přikryl, Radek (referee) ; Obruča, Stanislav (advisor)
The master‘s thesis is focused on the study of biodegradation of polyhydroxyalkanoates, namely polymer polyhydroxybutyrate. The first part of the thesis is focused on the study of biodegradation of polyhydroxybutyrate in the form of crystalline granules of PHB and PHB films using selected species of microorganisms from bacteria, yeasts and fungi. As a representative of bacteria was chosen microorganism Delftia acidorovans, as yeast was selected Aureobasidium pullulans and Aspergillus fumigatus as fungi. PHB depolymerase activity was measured employing turbidemtiric method with suspension of PHB granules as substrate. The results showed that D. acidorovans can partially degrade PHB. On the contrary A. pullulans cannot effectively degrade PHB. The most significant degradation ability revealed A. fumigatus, which was able to degrade PHB completely. Extracellular enzymes excreted by these microorganisms when cultivated on PHB materials as sole carbon sources were analyzed by SDS-PAGE. The second part of the thesis deals with the biodegradation of PHB in the form of PHB film, PHB hardened foil and PHB Nanoul fabric using standard composting test. Semi-solid cultivation showed positive results. In the interval from 14 days to two months were all forms of the PHB completely biodegraded. With semi-solid cultivation was also studied biodegradation rate of the polyurethane elastomeric films which were modified by partial replacement of polyester polyol by PHB. The test samples were prepared using PHB from Sigma and the PHB samples prepared at the Faculty of chemistry VUT. Samples with different concentrations of the dispersed PHB (1 %, 5 % and 10 %) in the polyurethane were also object of the study. At the end of the cultivation (after 2 months) were measured mechanical properties in tension of the material, then efficiency of biodegradation by gravimetric analysis and modification of the material surface by microscopic analysis.
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Azole resistance in Aspergillus fumigatus: genetic background and mechanisms of spread in the Czech Republic
Holíková, Kristýna ; Hubka, Vít (advisor) ; Chrenková, Vanda (referee)
Aspergillus fumigatus is a widespread saprophytic fungus. As an opportunistic pathogen it can also cause aspergillosis, which can manifest itself as a life-threatening infection in immunocompromised patients. Azole derivatives constitute first-line therapy of aspergillosis, but the increase worldwide of azole-resistant A. fumigatus strains represents a serious clinical problem. So far most of the molecular mechanisms causing azole resistance are dependent on the cyp51A gene. Studies of the last decade have shown that primarily because of the use of azole fungicides in agriculture, azole-resistant strains of A. fumigatus are selected in the environment. This subsequently complicates the treatment of patients with aspergillosis, and the incidence of infections unresponsive to treatment with azole antifungals increases. Increasing incidence of azole antifungals-resistant infections has become a growing concern: yet the prevalence of azole resistance has not yet been assessed in Czech Republic. Therefore, the first objective of this thesis was to determine Czech Republic's prevalence of azole resistance in clinical strains of A. fumigatus. Those findings permitted the observation of the molecular-genetic mechanisms of this resistance. Second aim was to study environmental prevalence of azole resistance...
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Analysis of pulmonary samples infected with Aspergillus fumigatus and Pseudomonas aeruginosa by scanning electron microscopy
Juříková, Tereza ; Benada, Oldřich (advisor) ; Nebesářová, Jana (referee)
Despite the significant progress in medicine, infectious diseases are life-threatening thanks to an increasing number of multiresistant strains of microorganisms and late detection of pathological agents. An opportunistic fungus Aspergillus fumigatus cause respiratory system diseases called aspergillosis. The invasive pulmonary aspergillosis affects immunocompromised patients after inhalation of ubiquitous conidia of A. fumigatus and results in 450,000 deaths per year. The biofilm formation in the infected tissue protects A. fumigatus against antimicrobial drugs. Late therapy may not be effective. Infection of immunocompromised patients and biofilm formation is characteristic also for gram negative bacteria Pseudomonas aeruginosa, which is due to the production of many factors of virulence and multiresistance a dreaded opportunistic pathogen. Scanning electron microscopy (SEM) provides detail information about morphology of microorganisms with the resolution in range of tens of nanometers that allows to observe microorganisms in the infected tissue and its pathological changes. Mass spectrometry allows to detect infection and its course based on identification of characteristic microbial molecules. The aim of this study was to optimize sample preparation of tissues infected with A. fumigatus or P....
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Genetic background and spread of azole resistance in Aspergillus fumigatus
Holíková, Kristýna ; Hubka, Vít (advisor) ; Lysková, Pavlína (referee)
Aspergillus is a globally widespread saprophytic filamentous genus of fungi, including opportunistic pathogenic species that cause a disease called aspergillosis. Azole derivatives have an irreplaceable role in the treatment of aspergillosis. These drugs inhibit the biosynthetic pathway of ergosterol. That leads to disruption of the fungal plasma membrane. However, nowadays, the rate of occurrence of azole-resistant fungi is rapidly increasing, which also increases the mortality of the patients. The aim of this bachelor thesis is to summarize the current knowledge associated with azole resistance with focus on its genetic background and global distribution. The main emphasis is given on the species Aspergillus fumigatus which is the most common agent of aspergillosis. Resistance to azole derivatives arises from prolonged fungi exposure to azole drugs or fungicides. The most common origin of azole resistance relates to the use of azole fungicides in agriculture. There are several ways how the resistance works. Most of them, however, relate to changes in the cyp51A gene, which is affected by azoles, and its promoter, with the most frequent mutation being TR34/L98H. The most common mechanism of the resistance that is not associated with changes in the cyp51A gene is increased expression of efflux...
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Analysis of pulmonary samples infected with Aspergillus fumigatus and Pseudomonas aeruginosa by scanning electron microscopy
Juříková, Tereza ; Benada, Oldřich (advisor) ; Nebesářová, Jana (referee)
Despite the significant progress in medicine, infectious diseases are life-threatening thanks to an increasing number of multiresistant strains of microorganisms and late detection of pathological agents. An opportunistic fungus Aspergillus fumigatus cause respiratory system diseases called aspergillosis. The invasive pulmonary aspergillosis affects immunocompromised patients after inhalation of ubiquitous conidia of A. fumigatus and results in 450,000 deaths per year. The biofilm formation in the infected tissue protects A. fumigatus against antimicrobial drugs. Late therapy may not be effective. Infection of immunocompromised patients and biofilm formation is characteristic also for gram negative bacteria Pseudomonas aeruginosa, which is due to the production of many factors of virulence and multiresistance a dreaded opportunistic pathogen. Scanning electron microscopy (SEM) provides detail information about morphology of microorganisms with the resolution in range of tens of nanometers that allows to observe microorganisms in the infected tissue and its pathological changes. Mass spectrometry allows to detect infection and its course based on identification of characteristic microbial molecules. The aim of this study was to optimize sample preparation of tissues infected with A. fumigatus or P....
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Study of biodegradation of poly(hydroxy alkanoates).
Wurstová, Agáta ; Přikryl, Radek (referee) ; Obruča, Stanislav (advisor)
The master‘s thesis is focused on the study of biodegradation of polyhydroxyalkanoates, namely polymer polyhydroxybutyrate. The first part of the thesis is focused on the study of biodegradation of polyhydroxybutyrate in the form of crystalline granules of PHB and PHB films using selected species of microorganisms from bacteria, yeasts and fungi. As a representative of bacteria was chosen microorganism Delftia acidorovans, as yeast was selected Aureobasidium pullulans and Aspergillus fumigatus as fungi. PHB depolymerase activity was measured employing turbidemtiric method with suspension of PHB granules as substrate. The results showed that D. acidorovans can partially degrade PHB. On the contrary A. pullulans cannot effectively degrade PHB. The most significant degradation ability revealed A. fumigatus, which was able to degrade PHB completely. Extracellular enzymes excreted by these microorganisms when cultivated on PHB materials as sole carbon sources were analyzed by SDS-PAGE. The second part of the thesis deals with the biodegradation of PHB in the form of PHB film, PHB hardened foil and PHB Nanoul fabric using standard composting test. Semi-solid cultivation showed positive results. In the interval from 14 days to two months were all forms of the PHB completely biodegraded. With semi-solid cultivation was also studied biodegradation rate of the polyurethane elastomeric films which were modified by partial replacement of polyester polyol by PHB. The test samples were prepared using PHB from Sigma and the PHB samples prepared at the Faculty of chemistry VUT. Samples with different concentrations of the dispersed PHB (1 %, 5 % and 10 %) in the polyurethane were also object of the study. At the end of the cultivation (after 2 months) were measured mechanical properties in tension of the material, then efficiency of biodegradation by gravimetric analysis and modification of the material surface by microscopic analysis.
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