National Repository of Grey Literature 151 records found  beginprevious94 - 103nextend  jump to record: Search took 0.01 seconds. 
Determination of acrylamide content in coffee
Janíčková, Vlasta ; Obruča, Stanislav (referee) ; Svoboda, Zdeněk (advisor)
The aim of this bachelor thesis was determination of the acrylamide levels in selected types of roasted ground coffee. The particular samples of coffee differed in brand and composition. In practical part the determination of acrylamide levels in coffee extracts was analyzed by using gas chromatography in combination with mass spectrometry.
Impact of nitrogen fertilization and drought on gliadins content in winter wheat
Odstrčilová, Eva ; Obruča, Stanislav (referee) ; Hrstka, Miroslav (advisor)
In this diploma thesis the impacts of both nitrogen fertilization and drought on the content of proteins of the gliadin fraction in case of a winter wheat variety Tiguan were observed. Selected samples were cultivated at two locations in a total duration of two years. Two different conditions were selected: one without the nitrogen fertilization (0 kg N/ ha) and the other with the nitrogen fertilization in 140 kg N/ ha concentration. Second observed factor was the drought which was ensured by roofs above the crops and their cultivation in common climatic environment. Gliadin fraction was separated by the A-PAGE method and the protein quantification carried out by a computer densitometry. Such nitrogen fertilization caused a significant increase of gliadins, especially -1,2 and -5 fractions. Stress induced by the drought caused an increase of gliadin content compared to the control sample, particularly in case of - and - fractions. The most important factor influencing the gliadin content in grains was therefore the nitrogen fertilization in a dry environment. The observed increase of gliadin content was lower in case of the sample which was fertilized in a humid environment than in case of the sample which was fertilized in the dry one.
Identification of PHA producing bacteria employing molecular techniques
Gajdová, Barbora ; Obručová,, Hana (referee) ; Obruča, Stanislav (advisor)
This diploma thesis deals with identification of bacteria which are capable of producing polyhydroxyalkanoates (PHAs). Work included testing variety of genera including Pseudomonas, Lactobacillus, Bifidobacterium, thermophilic cultures and samples gathered from natural sources. Bacteria were investigated by molecular technique polymerase chain reaction – PCR. An amplification of the PHA synthase gene (phaC) was analyzed. In the first reaction phaC and 16S rRNA genes were tested at the same time. 16S rRNA gene is used as control for bacterial DNA and as an identification tool for natural source samples. This multiplex PCR used multiple primers in PCR mix. Second reaction search for amplicon specific for catalysing biosynthesis mcl-PHA (phaC1). The presence of the PHA synthase gene was verified in 11 samples which were Bifidobacterium breve CCM 7825T, Lactobacillus rhamnosus CCM 1825T, Lactobacillus zeae CCM 7069T, Lactobacillus delbrueckii subsp. bulgaricus CCM 7190T, Lactobacillus plantarum CCM 7039T, Pseudomonas gessardii, Pseudomonas fulva, Arthrobacter protophormiae, Curtobacterium flaccumfaciens, Mycobacterium neoaurum and Staphylococcus lentus.
Detoxification of lignocellulose hydrolyzates
Vašíčková, Monika ; Pořízka, Jaromír (referee) ; Obruča, Stanislav (advisor)
The aim of this work was study of the detoxification of lignocellulose material hydrolysates and to investigate sawdust suitability as a substrate for microbial production of PHA by bacteria Burkholderia cepacia and Burkholderia sacchari. In the experimental part of the work the most suitable way of detoxification of model and real hydrolysate was studied. After that, detoxification methods used were evaluated. Criteria for evaluation were concentration of polyphenols as the most important microbial inhibitors and reduction saccharides as the main carbon substrate. Furthermore, fermentability of the hydrolysates was also tested by cultivation of two bacteria capable of PHA accumulation. Burkholderia sacchari demonstrated higher ability to accumulate PHA then Burkholderia cepacia. Then in the summary – most effective way for detoxification was ‚overliming‘. Major increase of PHB in biomass was obtained when Burkholderia sacchari was cultivated on media gained by application of overliming of real lignocellulose hydrolysate. However, total gains of PHB were more likely low and then sawdust can not be considered as a substrate for PHB production at industrial scale.
Utilization of PHA producing bacteria in bioremediation technologies
Šuráňová, Zuzana ; Sedláček, Petr (referee) ; Obruča, Stanislav (advisor)
The aim of this work is study of utilization of PHA producing bacteria in bioremediation technologies. For this study were used bacteria Pseudomonas putida KT2440 and two isolates from soil contaminated by petroleum - Pseudomonas gessardii (D2) a Pseudomonas fulva (D3). The experimental part describes especially study of feather biodegradation using selected microbial strains. All the tested bacterial strains were capable of feather degradation and utilization as the sole carbon source. During biodegradation experiment, we monitored weight loss of feather, protease and keratinase activity, concentration of bacterial biomass and PHA content as well as pH. The highest biodegradation ability and keratinase activity was observed in Pseudomonas putida. None of tested bacteria accumulated detectable amount of PHA during growth on waste feather, nevertheless, bacterial biomass grown during feather degradation can be used as an inoculum for PHA production on waste frying oil and octanoic acid. Using this experimental setup, high PHA content (54% of cell dry weight) was achiaved in Pseudomonas putida. Another part of the thesis deals with biodegradation of petroleum oil. The highest capability of growth on this carbon source were determined in Pseudomonas fulva.
Study on pretreatment and hydrolysis of selected lignocellulose materials
Kovářová, Markéta ; Dvořák, Miloš (referee) ; Obruča, Stanislav (advisor)
This diploma thesis is focused on study of chemical and enzymatical hydrolysis of raw wood material. The aim of this work was to find the suitable method for pretreatment of selected lignocellulose materials. The theoretical part deals with characterization of lignocellulosic material and its components. There are also subscribed various pretreatment methods and their effect on hydrolysis of sawdust. In experimental part of the work the most appropriate approach of pretreatment and hydrolysis of sawdust was studied. Criteria for the selection of suitable method was concentration of saccharides as desired product of hydrolysis and also concentration of the most important microbial inhibitors - polyphenols. Application of 96% ethanol or 5% H2O2 were identified as the most promising pretreatment methods which enhanced yields of fermentable sugars about 30 %. Further, we also performed cultivation of bacteria Burkholderia cepacia and bacteria Burkholderia sacchari using solution obtained by hydrolysis of lignocellulose material.
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.
Optimisation of Isolation Procedure and Characterization of Amorphous PHB granules
Kratochvíl, Zdeněk ; Obruča, Stanislav (referee) ; Kalina, Michal (advisor)
First artificial PHB granules were prepared under the terms of this thesis. The effect of used PHB solvent, ultrasonic bath temperature and time, solvent evaporation temperature and stabilizing agent nature was investigated using dynamic and electrophoretic light scattering. The most proper parameters were demonstrated at samples which were prepared by dissolving of PHB in chloroform, stabilizing with CTAB or lecithin, ultrasonifying at 35 °C followed by chloroform evaporating at 60 °C. Based on ATR-FTIR and Raman spectroscopy results, it was found out that PHB within the artificial granules were in crystalline form. The native PHB granules were isolated from Cupriavidus necator using either lysosyme, deoxyribonuclease and cell disruption by ultrasonification or digestion with alcalase, SDS and EDTA. Granules obtained by both isolation procedures were characterized by ATR-FTIR, Raman spectroscopy, light scattering techniques and DSC. According to the analyses results, the second mentioned procedure turned out to be more effective for obtaining the polymer in amorphous state. Furthermore, the polymer within granules recovered by using this procedure was thermally more stable. Last but not least, the native PHB granules samples were exposed to effect of acetone, lipase and sodium hypochlorite, assuming that polymer crystallinity should be increased by these chemicals in varying degrees. The highest degree of crystallinity was achieved after their treatment with lipase.
Polyhydroxyalkanoates and their role in bacterial biofilms
Rucká, Markéta ; Samek,, Ota (referee) ; Obruča, Stanislav (advisor)
This master thesis deals with polyhydroxyalkanoates (PHA) and their role in bacterial biofilms. In the theoretical part the polyhydroxyalkanoates, bacterial biofilm and the relationship between them were reviewed. The experimental part focused on differences in PHA production by planktonic and biofilm cells. In order to study selected topic, bacterial strains of Burkholderia cepacia and Burkholderia sacchari were cultivated using a CDC biofilm reactor. The attention was paid to quantity and especially to the form in which PHA occurs in planktonic and biofilm cells. Results of Raman spectroscopy have shown that PHA exists exclusively in native amorphous form in planktonic bacterial cells. On the other hand, in biofilm PHA occurs also in a partially crystalline form. In addition, the resistance of planktonic and biofilm cells against various stress factors and the effect of osmotic stress on PHA production was tested too. According to the results of the experiment, when the bacteria were exposed to different stress factors (high temperature, low temperature, presence of detergent and so forth) biofilm cells showed a higher stress resistance than planktonic cells. Apart from slowing cell growth and reproduction, increased osmotic pressure in the culture medium also caused decrease of PHA production. In addition, planktonic cells responded to external stimuli more sensitively than biofilm ones.
Anisotropy techniques in study of cytoplasm
Sýkorová, Kateřina ; Obruča, Stanislav (referee) ; Mravec, Filip (advisor)
The main goal of this thesis was to compare experiments using time-resolved anisotropy and steady-state anisotropy for measuring in bacteria strain Cupriavidus necator. Fluorescent probe for anisotropy imaging was chosen BCECF_AM, which is derivate of fluorescein. Using experiment in system glycerol/water with fluorescein, anisotropy has been verified and calculated molecular hydrodynamic volume of a single fluorescein molecule, which approximately corresponded with real value. By using fluorescence imaging anisotropy microscopy, images and values of average anisotropy in cells were taken. Images of living cells (bacteria) of CN H16 and mutant CN PHB-4 showed differences, mainly in the uniformity of the inside environment.

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