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Study on resistance of bacteria to selected stress factors
Miléřová, Miluše ; Samek,, Ota (referee) ; Obruča, Stanislav (advisor)
The aim of the master thesis was to study the effect of the accumulation of polyhydroxyalkanoates (PHA) for bacterial resistance to selected stress factors. In the theoretical part the selected stress factors, polyhydroxyalkanoates and the involvement of polyhydroxyalkanoates into stress response of bacteria were reviewed. In the experimental part we used bacteria Cupriavidus necator H16 and its mutant strain Cupriavidus necator H16/PHB-4 unable of polyhydroxybutyrate (PHB) accumulation. The resistance of above-mentioned bacterial strains against thermal and osmotic stress was tested. According to the results of the experiment, when the bacteria were exposed to three different concentrations of NaCl (50, 100 and 200 g/l) PHB accumulating strain showed a higer resistance to hyperosmotic stress than the strain unable of PHB accumulation. There was demonstrated with Raman spectroscopy that in the hyperosmotic environment induced crystallization of the intracellular PHB granules. Transmission electron microscopy indicated that strain Cupriavidus necator H16/PHB-4 is subject to plasmolysis during hyperosmotic stress. As a consequence the hyperosmomotic stress occurs to the aggregation intracellular PHB granules in strain Cupriavidus necator H16 but there is no plasmolysis or is much less intensive.
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Study on resistance of bacteria to selected stress factors
Miléřová, Miluše ; Samek,, Ota (referee) ; Obruča, Stanislav (advisor)
The aim of the master thesis was to study the effect of the accumulation of polyhydroxyalkanoates (PHA) for bacterial resistance to selected stress factors. In the theoretical part the selected stress factors, polyhydroxyalkanoates and the involvement of polyhydroxyalkanoates into stress response of bacteria were reviewed. In the experimental part we used bacteria Cupriavidus necator H16 and its mutant strain Cupriavidus necator H16/PHB-4 unable of polyhydroxybutyrate (PHB) accumulation. The resistance of above-mentioned bacterial strains against thermal and osmotic stress was tested. According to the results of the experiment, when the bacteria were exposed to three different concentrations of NaCl (50, 100 and 200 g/l) PHB accumulating strain showed a higer resistance to hyperosmotic stress than the strain unable of PHB accumulation. There was demonstrated with Raman spectroscopy that in the hyperosmotic environment induced crystallization of the intracellular PHB granules. Transmission electron microscopy indicated that strain Cupriavidus necator H16/PHB-4 is subject to plasmolysis during hyperosmotic stress. As a consequence the hyperosmomotic stress occurs to the aggregation intracellular PHB granules in strain Cupriavidus necator H16 but there is no plasmolysis or is much less intensive.
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Study of bioremediation of some organic polutants by Cupravidus necator
Miléřová, Miluše ; Hurtová, Jana (referee) ; Obruča, Stanislav (advisor)
The aim of this work is the study of bioremediation of p-nitrophenol using bacteria Cupriavidus necator. The theoretical part contains a summary of organic pollutants and the bioremediation aproaches used to remove them from the environment. In the experimental part of this work we used bacteria Cupriavidus necator H16 and its mutant strain Cupriavidus necator H16/PHB-4 unable of PHB accumulation. The experiments were performed with different concetrations of p-nitrophenol and also under none-optimal conditions. Apart from concentration of p-nitrophenol, viability of the bacterial cultures was determined by flow cytometry. During cultivation in progress for sub-optimal conditions with a concentration of 50 mg•l-1 p-nitrophenol at 4°C using a flow cytometer seemed more resistant bacteria Cupriavidus necator H16. On the contrary strain Cupriavidus necator H16/PHB-4 was more resistant at 37 °C. The biodegradation assay was also performed in fermentor, during 51 hours lasting cultivation, bacterial culture degraded 65 % of p-nitrophenol and moreover decreased wavelenght of maximum in absorption spectra from 401 m to 384 nm was observed. The quantity of PHB was analyzed by gas chromatography with FID detector along with the p-nitrophenol determined by spectrophotometry, whose maximum content of PHB was achieved in 20 hour of cultivation
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