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The utilization of atomic force miscroscopy to study of selected bacterial strain
Nováková, Simona ; Slaninová, Eva (referee) ; Smilek, Jiří (advisor)
The subject of the bachelor’s thesis was the study of selected bacterial strains by a selected method of atomic force microscopy. Thermophilic purple bacteria – Rhodoblastus acidophilus, Rhodobaca barguzinensis – were investigated. The main aim of this theses was focused on optimizing the usage of this microscopic method for imaging in an aqueous environment with the most appropriate fixation of sample. Focusing on bacterial strains demanded to preserve the viability of microorganisms and to observe optimal conditions for maintaining the native state during the measurement process. Furthermore, mechanical properties were evaluated – Young’s modulus and adhesion. The morphology of individual samples was compared for samples of the same species in different pH liquid environments and in environments with different concentrations of dissolved NaCl salt. The ability to produce PHA granules in purple bacteria was also targeted, however, due to the absence of first-class PHA synthase, PHA was not detected. The effects of different cultivation parameters such as different cultivation time or different pH of the environment were compared. Imaging of bacteria was carried out using the SNL-10 tip, which is suitable for bacterial samples in a liquid environment, and the measurement itself was carried out in QITM mode. A glass substance covered with a layer of Poly-L-lysin was used for immobilization. Finally, the mechanical properties were evaluated through Young’s modulus and adhesion for samples with various environmental factors.
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Biotechnological production of polyhydroxyalkanoates employing extremophilic purple bacteria
Rubanová, Blanka ; Samek, Ota (referee) ; Obruča, Stanislav (advisor)
The presented thesis focuses on studying the metabolism of polyhydroxyalkanoates (PHAs) in extremophilic purple bacteria, specifically Rhodoblastus acidophilus and Rhodobaca barguzinensis. The bacteria's ability to synthesize PHAs was examined in various media and using different carbon sources. Initially, optimal conditions including media volume, light presence, cultivation duration, and inoculum size were determined for the most suitable bacterial growth. Subsequently, the PHA content in bacteria cultivated in different media and with various carbon sources was analysed using gas chromatography. For a better characterization of bacterial metabolism and morphology, scanning transmission electron microscopy (STEM) and Fourier-transform infrared spectroscopy (FTIR) were used. The bacteria's ability to synthesize PHA was also examined at the genotype level using polymerase chain reaction (PCR) method. The presence of the phaC gene, encoding PHA synthase class I, was detected in bacterial DNA. Additionally, an experiment was conducted to cultivate bacteria under conditions favourable for the synthesis of microbial pigments (carotenoids and bacteriochlorophyll a). The absorption spectrum of extracted pigments was measured using UV-VIS spectroscopy.
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