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Hydrogel carriers of microorganisms for modern environmental aplications.
Súkeník, Martin ; Slaninová, Eva (referee) ; Sedláček, Petr (advisor)
This bachelor thesis deals with the optimization of cultivation and gelation procedures by bacterium Azotobacter vinelandii, which belongs to a PGPR group, capable of synthesis of intracellular polyhydroxyalkanoates and extracellular alginate. The alginate produced by the bacteria is crosslinked with a calcium chloride solution to form a hydrogel carrier containing the described bacterium. This unconventional concept simplifies bacterial encapsulation and production of hydrogel carriers, furthermore expands its usability in modern environmental applications. In the first part of this thesis, three strains (DSM 85, 87, 720) were selected to measure a concentration of produced alginate, its molecular weight was determined by a SEC-MALS technique and M/G ratio was analysed by infrared spectroscopy. The Azotobacter vinelandii strain DSM 87 reached the highest concentration of the alginate (4.9 ± 0.6) g/l by gravimetric determination on the 5th day of cultivation. The concentration of produced PHB ranges from 48 to 6 % of CDW, which was determined by gas chromatography. Nevertheless, the strain DSM 720 showed the best gelation properties and was used in the second part of this thesis for further optimization of the cultivation process, and for the analysis the formation of gelation procedure under different temperatures, gelation time and concentrations of crosslinking solution. The formed gels were compared by rheological measurements of amplitude and frequency tests.
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Preparation and characterization of hydrogel delivery systems from poly-gamma-glutamic acid
Mai, Thuy Ha ; Smilek, Jiří (referee) ; Sedláček, Petr (advisor)
The presented diploma thesis focuses on the development and preparation of model poly--glutamic acid based hydrogel carrier systems. For the hydrogel carrier preparation, methods based on physical interactions between polyelectrolyte and oppositely charged multivalent ion or oppositely charged macromolecule were proposed. Based on the pilot experiments, trivalent iron cation and chitosan were selected as suitable crosslinking agents. By crosslinking -PGA via ferric cations a successful bead formation has been accomplished and attempts have been made for a preparation of beads smaller than 1 000 m by employing microencapsulation techniques. Rapid disintegration of -PGA beads occurred upon immersion of the beads in water making these systems unsuitable for drug carrier applications. Interactions between -PGA and chitosan lead to polyelectrolyte complexes formation and by optimizing concentrations and pH of polyelectrolyte solutions, a formation of homogenous looking hydrogel with high water content (>0,9) has been achieved.
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Self-encapsulation of Plant Growth Promoting Rhizobacteria as a way towards new generation of bioinoculants
Gašparová, Dominika ; Obruča, Stanislav (referee) ; Sedláček, Petr (advisor)
This bachelor thesis focuses on Plant Growth-Promoting Rhizobacteria that can be used as a suitable ecological alternative to conventional fertilizers. However, most of today's approaches to incorporating PGPR into the process of soil fertilization are convoluted and costly. Crosslinking of alginate self-produced by PGPR offers a new possibility of plantgrowth- promoting bacteria encapsulation. The aim of this thesis consists of preparing gel matrices with incorporated bacteria, followed by testing the bacteria's viability and quantity. Firstly, experiments were carried out to determine various properties of gels produced by the chosen representative bacteria Azotobacter vinelandii. These properties include the molecular weight of alginate (with the highest molecular weight of strain CCM 289 (329,78± 6,8) kDa), the alginate's amount in the gel, the content of PHB (34%-44% CDW), and the gel's overall rheological properties. The complex modulus (as a representation of rheological properties) of the firmest gel reached the value of 13,34 kPa. The bacteria content was examined by flow cytometry, the CFU method, and spectrophotometry. The viability of bacteria was determined by analyzing the fluorescence intensity via fluorescent dyes (propidium iodide, fluorescein diacetate, rhodamine 123, calcein AM), then by using the CFU method, and also via the plate method. Furthermore, the effects of various factors such as different pH levels (pH 3, 7, and 10) or adding the specific alginatedegrading enzyme alginase were also examined. Releasing of the bacteria was observed over the course of seven days using flow cytometry and the CFU method. The plate method proved the bacteria's survival after gelation and without any source of carbon. The largest disintegration of gels occurred in acidic pH. Moreover, the effect of alginase on crosslinked bacterial gels and synthetic alginate were very similar. The survival of bacterial cultures in gel and their continuous release are significant findings in the development of novel bioinoculants based on this new concept.
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The stress and modal analysis in parametric adaptive CAD programs
Sedláček, Petr ; Ondrůšek, Čestmír (referee) ; Kuchyňková, Hana (advisor)
This thesis is focusing on the use of the finite element method (FEM) in program environment of Autodesk Inventor Professional (AIP) 2010. For the analysis of the components or assemblies with FEM serves the Strength analysis module of the AIP 2010, whose environment and functions are detailed in this thesis. At the conclusion practical examples of modal and static analysis on the synchronous generator rotor model are demonstrated including a brief evaluation of the results.
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Biotechnological production of sophorolipids
Šimšová, Veronika ; Sedláček, Petr (referee) ; Obruča, Stanislav (advisor)
This diploma thesis deals with the microbial production of sophorolipids by the Starmerella genus yeasts. The theoretical part of the thesis includes general characteristics of biosurfactants with the focus on sophorolipids. There are described the options of biotechnological production of sophorolipids and fields of their possible applications. Furthermore, the theoretical part deals with the describtion of Starmerella bombicola yeast, which is often used for biotechnological production of sophorolipids. Six strains of the Starmerella genus were cultured in the basic medium suitable for sophorolipid produsction. The amount of produced sophorolipids was tested by the emulsification capacity assay, solubilization of crystalline anthracene assay, measuring the surface tension by the Du-Noüy-Ring method and determination of the sophorolipid concentration by extraction with ethyl acetate. The purity of the extracted sophorolipids was inspected by the Fourier Transform infrared spectrosopy (FT-IR) Based on the results, the Starmerella bombicola CBS 6009 and the Starmerella anomalae CBS 14178 strains were studied in greater detail. They were cultured in several production media of different composition and the effect of the individual components on the ability of the sophorolipid production was monitored. Based on the results, it was evaluated that the composition of the medium has a great influence on the production ability of the strains. The highest production rate of sophorolipids was achieved in the basic production medium and so was in the medium containing molasses and Indian waste oil. The cultivation mode has great effect on the sophotolipid production rate. It has been found that when cultured in a bioreactor, the strains produced sophorolipids in a larger amount and of a different quality than in the shaker flasks.
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Microrheology in systems of polymeric colloids
Bjalončíková, Petra ; Sedláček, Petr (referee) ; Venerová, Tereza (advisor)
My bachelor’s thesis was aimed to deal with evaluation of microrheology method in the research of polymer colloids. Used polymers were poly(sodium 4-styrenesulfonate) and sodium carboxymethyl celullose. For measuring of microrheology were used particles with different radius (1 m and 4 m). The results obtained with passive microrheology were compared with results obtained with clasical rheology. It was found, that both substances have viscous charakter. The values of polymer viscosity were similar for dilute solutions in both methods, but for concentrated solutions deviations were found. The reason are polymer nets, which do not allow sufficient movement of particles in concentrated solutions.
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Dry gel forms - aerogels, xerogels - preparation, properties and potential use.
Sedlář, Marian ; Smilek, Jiří (referee) ; Sedláček, Petr (advisor)
The content of this bachelor thesis was to find out what influence has the drying of hydrogel on its internal structure on an appropriate model hydrogel system. In the theoretical part of this thesis selected methods of structural analysis that are commonly used for characterization on gels in their original hydrated state and in dry state were described. In the practical part, agarose based hydrogels with different concentrations and with various additions of polyelectrolytes were chosen as the model hydrogel system. Cryo-scanning electron microscopy and turbidimetry were used for the structural analysis of hydrogels. For the dry gels, scanning microscopy and mercury porosimetry were used. The obtained data and results for our model system can be use in analyse of other hydrogel systems and their dry forms.
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Application of thermal analysis in physiological characterization of microorganisms
Kočiová, Silvia ; Obruča, Stanislav (referee) ; Sedláček, Petr (advisor)
This diploma thesis deals with the applicability of thermal analysis in the influence of stress factors on microorganisms. The main aim of the presented work was to design and implement a series of experiments to thest the usability of advanced methods of thermal analysis in the characterization of microorganisms. Two bacterial strains were used as model organisms: Cupriavidus necator H16 and its mutant strain Cupriavidus necator PHB-4, which differs in the ability to produce polyhydroxyalkanoates. The basic technique used thermogravimetric analysis (TGA), which was optimized and applied in the study of water transport, behavior and determination of intracellular water content with respect to the influence of the presence of intracellular PHB granules. The results of this method were subsequently supported by TEM photos.
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Experimental and computer modeling diffusion of low-molecular solutes in gel – based carriers
Masár, Lukáš ; Gregorová, Eva (referee) ; Sedláček, Petr (advisor)
This diploma thesis is focused on combination of experimental study and computer modelling of diffusion processes in gel phases. The aim of experimental part of the diploma thesis was to test and optimize the setting of the diffusion coefficient in gel medium by using the method of horizontal diffusion cells, commonly used for study of diffusion processes through membranes. Specific description of experiments was to determinate the impact of presence of reactive component in inert hydro-gel carrier on final value of diffusion coefficient of low-molecular model diffusion probe. The defined dependencies were subsequently combined with computer simulation of diffusion process in a properly designed model in order to determinate the experimentally unavailable system parameters. The stated combination of both approaches was proved to be an appropriate instrument for studying of hydro-gels with a wide potential especially in the field of preparation of hydro-gel carriers with controlled release of active substances.
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Adhesion Properties of Semi-IPN Hydrogels
Candráková, Simona ; Sedláček, Petr (referee) ; Kalina, Michal (advisor)
This Diploma thesis deals with optimization of the hydrogel preparation with various additions of substances affecting adhesion, studying the adhesion of prepared hydrogel systems and modifying their adhesion properties. Prepared hydrogels were agarose, alginate and gellan polymer systems with additions of acrylic acid, acrylamide, calcium chloride and Tween 20. The experimental part of the diploma thesis focuses first on optimizing the preparation of individual hydrogels, from which, according to certain criteria, suitable representatives were selected to study adhesion and its controlled modification. Agarose and gellan hydrogels were selected as suitable representatives, which were then used in rheological measurements. Based on these measurements, the effect of the adhesive force and the adhesive work of individual materials was evaluated. It was found that the best adhesion properties of the materials used are unadjusted hydrogels, in the case of hydrogels with the addition of another substance, a negative effect on adhesion was observed, when the adhesion force was reduced and also the adhesion work was reduced.
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