|
|
Utilzation of physico-chemical analyses in study on microbial stress-response
Slaninová, Eva ; Pekař, Miloslav (referee) ; Sedláček, Petr (advisor)
This diploma thesis deals with the utilization of physico-chemical analysis in study on microbial stress–response. The main content of this work was to propose and optimize techniques and methods which are generally used in different industries. Two bacterial strains, Cupriavidus necator H16 and its mutant strain Cupriavidus necator PHB-4 producing polyhydroxyalkanoates (PHA) under certain conditions, were used as model microorganisms. Initially, microscopic teques such as transmission electron microscopy (TEM), cryo scanning electron microscopy (cryo SEM) and atomic force microscopy (AFM) were proposed and tested for the characteriozation of morphological differences of bacteria. Furthermore, viscoelastic properties of bacteria were determined and compared by the oscillatory tests of the rheology method considering another type of samples. Thermal analysis methods, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) in particular, focused on water transport and behavior of intracellular water influenced by presence of the granules of PHB in bacteria. The last technique, utilized in the study, was dynamic and electrophoretic light dispersion during pH changes for characterization of the surface properties of bacteria such as size, zeta potential and the isoelectric point.
|
|
|
Preparation and application particles from copolymer of P(3HB-co-4HB)
Ostanina, Kseniia ; Sedláček, Petr (referee) ; Obruča, Stanislav (advisor)
This bachelor thesis deals with preparation of particles from poly(3-hydroxybutyráte-co-4-hydroxybutyráte). Copolymer was dissolved in acetone and then the solution had been dosed into the anti-solvents. Acetone and anti-solvent are perfectly miscible. Theoretical part focuses on the properties of the copolymer, its production and potential use in medical applications. In the experimental part the copolymer was dripped into selected anti-solvents by syringe and pipette above and below the surface of anti-solvent. The following anti-solvent were chosen: water, methanol, dimethylsulfoxid (DMSO), 50 % acetone-water, 75% acetone-water, 50 % methanol-water, 75 % methanol-water mixtures. There were three copolymers used with different compositions of 4HB units (63 %, 87 % a 33 %). Copolymer composition was analyzed by gas chromatography. Copolymers were prepared by bacterial strain Aneurinibacillus sp. H1. Due to the results particles of size approximately 100-500 nm can be prepared by methods described in this work. The produced particles can be successfully used in medical applications.
|
|
|
Modelling of particle movement in liquid and hydrogel media
Orság, Miroslav ; Sedláček, Petr (referee) ; Pekař, Miloslav (advisor)
Main goal of this thesis was to became familiar with general mathematical description of particle motion in fluid and hydrogel media in COMSOL software. Simulate a basic Brownian motion of particles with various diameter in media with different density. According to software options, simulate motion in polymer structure or in viscoelastic media. Consider an options of the model for use in microrheology and suggest next process in this field.
|
|
|
Preparation, characterization and evaluation of application potential of semiIPN hydrogels
Papežíková, Hana ; Pekař, Miloslav (referee) ; Sedláček, Petr (advisor)
Aim of this thesis os to optimize set up of hydrogel based on semi-interpenetrated polymer networks. Polyhydroxyethylmethyl acrylate was chosen as an model example of hydrogel due to its common use in biomedicine. At first, thermoiniciation was used for preparation and changed to photoiniciation afterwards. Following the optimisation of the hydrogel set up with proper qualities, the polyelectrolyte sodium polystyrene sulfonate was implanted. Object of research was its impact on structure, flowing and transport features of hydrogels. All qualities were tested by drying, rheology, and fluorescence correlation spectroscopy. Results clearly validate influence of hydrogel features by polyelectrolytes.
|
|
|
Adaptation to adverse osmotic conditions as a tool for evolutionary enginnering of bacteria
Drotárová, Lenka ; Nováčková, Ivana (referee) ; Sedláček, Petr (advisor)
This bachelor thesis deals with the application of osmotic stress as a tool for evolutionary engineering of PHA producing bacterial strains. The aim of this thesis is to evaluate a bacterial adaptation to hypoosmotic environment, as an engineering tool in order to increase the production of PHA. The theoretical part focuses on the evolutionary engineering principle, methods of the strategy and the effect of physical factors on microorganism. The aim of experimental part was to performed an adaptive evolutionary experiment with the bacterial strain Halomonas halophila CCM 3662. Reduced osmotic pressure was used as a stressing factor during the serial cultivation. In order to generate PHA producing mutant strains, each passage was characterized using spectrophotometric and gravimetric method and by GC-FID. It was found that after the long-term cultivation, the mutant strain HH35, cultivated in 35 g/l NaCl, was associated with the highest biomass and PHB concentration. The 15th and 30th passages, along with the wild type strain H. halophila were subjected to further cell-robustness analysis with the application of hyper- and hypoosmotic shock. The stress response, viability of cells and morphological changes were analyzed using FC and TGA methods. Isolated polymers were characterized using FTIR analysis.
|
|
|
Structure and properties of bacterial biofilms
Mrázová, Kateřina ; Sedláček, Petr (referee) ; Obruča, Stanislav (advisor)
This thesis deals with the study of basic properties of cells of bacterial biofilm produced by PHA producing bacteria, specifically Burkholderia cepacia and Burkholderia sacchari. Two cultivation approaches were used to compare different types of cells: at first, the cells were cultivated in bioreactor providing both planktonic and biofilm attached cells, secondly, cells grown on Petri dishes were also included in the study. In experimental part the affinity of each type of cells to hydrophobic phase was studied using BATH method. It was found that sessile cells, either biofilm associated cells as well as cells taken from Petri dishes, prefer hydrophobic phases more than planktonic cells. Also size and Zeta potential were measured using Dynamic Light Scattering (DLS). It was found for studied samples that, cells in these samples tend to aggregate and the difference of size between both types of cells occurs only for biofilm of the strain Burkholderia cepacia. Finally the impact of presence various bacterial cells types on surface tension of water as well as amount of PHA cumulated in different types of cells were observed.
|
|
|
Utilization of physico-chemical analysis in study on cellular water
Matejčíková, Eva ; Obruča, Stanislav (referee) ; Sedláček, Petr (advisor)
The bachelor´s thesis deals with the study of methods, available at the Faculty of Chemistry at Brno University of Technology, that can be used to determine physical and chemical properties of cell water. The main task of this work was to specify which of these methods are suitable to determine physical and chemical properties of water in the cell and the properties of water occuring close to the cell surface. Based on the background research the series of experiments were proposed and implemented. Subsequently, this work deals with the optimisation of methods that were defined as the applicable techniques to determine the properties of cell water.
|
|
|
Optimalization of techniques of microrheology for characterization of biopolymer hydrogels
Dušenková, Alica ; Smilek, Jiří (referee) ; Sedláček, Petr (advisor)
The main aim of the bachelor thesis is optimalization of microrheological techniques for characterization of biopolymer hydrogels. Hydrogels, based on thermoreversible biopolymer agarose, were selected for these experiments. The influence of incorporated poly(sodium 4-styrenesulfonate) on structure and viscoelastic properties of agarose hydrogels was investigated through diffusion coefficient and MSD curves. Microrheological properties were studied by fluorescence correlation spectroscopy, by using fluorescent beads, which were embedded in hydrogel systems.
|
|
|
Preparation of humic hydrogels for appliaction in cosmetics
Pavlicová, Renata ; Mravec, Filip (referee) ; Sedláček, Petr (advisor)
This bachelor´s thesis is focused on the preparation and characterization of hydrogels containing humic substances and assessment of their potential usefulness in cosmetic practice. Main objective of the work was to develop a literature review focusing on the potential use of humic substances in the cosmetics and pharmaceutical industries. Furthermore, the aim was to prepare model hydrogels addition of soluble humic substances in traditional cosmetic compositions and their characterization by basic methods of analysis parameters. The main investigated parameters were consistency resulting gels (assessed subjectively and subsequently by rheology), their internal pH and dry matter. The experimental results showed that incorporation of humic substances into hydrogels resulting gels acceptable characteristics for further use in cosmetic applications.
|
|
|
Swelling behavior and bioactivity of humic acids hydrogels
Kozelková, Aneta ; Hynšt, Jaroslav (referee) ; Sedláček, Petr (advisor)
This thesis deals with the study of the biological activity of humic substances. Based on the literature review preparation procedures were optimized in order to develop new hydrogel forms containing humic substances and biopolymers with high swelling capacity. Besides methodology for the rapid assessment of the biological activity obtained in laboratory conditions were designed and tested. The experimental part focused on characterization of hydrogel samples by means of routine physico-chemical methods, the main attention was paid to sorption of water and release of humic substances into solution. Then the prepared hydrogel materials were tested focusing on the growth effects on the maize. The absorption of mineral nutrients by the roots of plants were studied as well. The motivation of this work comes from the potential of agricultural and environmental applications of such hydrogel materials resulting in a renewal of previously exhausted organic content of soils and consequent interruption of substantial soil degradation.
|
guest ::
