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Raman spectroscopy of prokaryotic cells
Večeríková, Paula ; Bernatová,, Silvie (referee) ; Samek, Ota (advisor)
The presented bachelor‘s thesis deals with the Raman spectroscopy of bacterial cells. This method proves to be very suitable for monitoring the culture conditions of these bacterial strains because it is essentially non-destructive and fast compared to gas chromatography. Due to it‘s non-destructive nature, it is possible to further cultivate the measured cells. This analytical method can also be used to sort and select individual cells with increased ability to produce PHB. This would enable the possibility to select the generation of so-called PHB superproducers. Polyhydroxybutyrate (PHB) belongs to the group of polyhydroxyalkanoates (PHA), which serve as a substitute for plastics made in the petrochemical industry, whose consumption is increasing, especially during a pandemic. Current biodegradable substitutes are based on starch, which, in turn, depletes nutritional material for humans and animals. This bachelor thesis can serve as a basis outline for reducing the cost of PHB production, because Raman spectroscopy can be used in cell culture as a sensor of PHB content in response to a bacterial strain. In the experimental part of the work, the Raman spectra of selected bacteria were measured, where the result showed the greatest response to PHB in Chelatococcus shambunathi and the lowest in the thermophilic isolate BZ (Paenibacillus sp.). Quantitative information on the content of PHA in bacteria was obtained by gas chromatography, where the highest content was the bacteria- Chelatococcus shambunathi and the lowest Termobacillus composti. The subject of the second part was the separation of a mixture of PHA-producing and non-PHA-producing bacterial cultures. The result clearly proves that the mixture is separable based on the intensity of the selected sorting parameter.
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Involvement of polyhydroxyalkanoates into stress response of bacteria
Kučera, Dan ; Skoumalová, Petra (referee) ; Obruča, Stanislav (advisor)
The aim of this work was to study the involvement of polyhydroxyalkanoates (PHA) into stress response of bacteria. The theoretical part of the thesis deals with the possibility of establishing the viability of microorganisms using modern techniques, in particular flow cytometry. Furthermore, the research focused on selected stress factors and PHA involvement in stress response was described. In the experimental part of the work the stress response with regard to the ability to accumulate PHA was assessed. Bacteria Cupravidus necator was used for the experiment. Its ability to accumulate PHA at a later stage of growth increased resistance to ethanol, high temperature and freezing. Conversely, the PHA-producing strain showed lower resistance to the action of inorganic acids and bases. This may be caused by different morphology of PHA-producing cells. One of partial objectives was also to study the possibilities of staining of living cells accumulating PHA using Nile red. The research proved that the dye penetrates into living cells at elevated temperature of 40-45°C. This temperature is not lethal to the cells and the intensity of staining is sufficient to distinguish PHA-producing cells using flow cytometry; that can be applied in the selection of industrial PHA producers.
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Utilization of physicochemical and spectroscopic techniques in study of stress-response of cyanobacteria
Skoryk, Maksym ; Šedrlová, Zuzana (referee) ; Sedláček, Petr (advisor)
Tato bakalářská práce je soustředěná na zkoumaní cyanobakterií, vystavených hyper a hyposmotickým stresům. Na základě literární rešerše byly navžené vhodné analytické metody určené ke studiu dvou modelových organismu - Synechocystis sp. PCC 6803 a Synechocystis sp. salina Wislouch CCALA 192. Celkem čtyři metody byly použité k charakterizaci osmoticky zatížených bakterií. Průtoková cytometrie byla použita k vyhodnocení viability. Fluorescenční sonda SYTOX Blue poskytla důvěryhodnou informaci ohledně viability bakterií. Propidium jodid naopak poskytl nezřetelnou informaci. Optické vlastnosti cyanobakterií byly prozkoumané pomoci UV-VIS absorpčních a turbidimetrických měření. Termogravimetrická analýza byla použita pro mapování změn obsahu vody v osmoticky stresovaných buňkách. Tato metoda ukazala. že PHB-positivní Synechocystis sp. PCC 6803 jsou pravděpodobně vice odolné vůči hyperosmotickým stresům než PHB-negativní. Plynová chromatografie byla použita ke kvantifikaci vnitrobuněčného PHB, který činil přibližně 1-2 % suché hmoty PHB-positivních buněk.
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Identification and isolation of PHA producing bacteria
Pernicová, Iva ; Ondrejovič, Miroslav (referee) ; Rychtera, Mojmír (referee) ; Obruča, Stanislav (advisor)
Polyhydroxyalkanoates (PHA) are microbial storage polyesters that represent a renewable and environmentally friendly alternative to petrochemical plastics. However, their production and use are severely disadvantaged by the high production cost. The use of extremophilic PHA producers is one of the ways to reduce the cost of PHA production. Extremophiles bring numerous advantages resulting from the high robustness of the process against microbial contamination. In this doctoral thesis, attention was focused on the study of PHA production using selected halophilic and thermophilic microorganisms. Representatives of the genus Halomonas were mainly from public collections of microorganisms. Two promising PHA producers on waste frying oil were identified, namely Halomonas hydrothermalis and Halomonas neptunia. Both strains achieved good PHA yields in flask experiments. With the addition of suitable structural precursors, they were also able to produce copolymers with interesting material properties. However, in the proposed thesis, the main emphasis was placed on the study of PHA production using thermophilic microorganisms. As a part of the work, the isolation of thermophilic PHA producers from various thermophilic consortia (active sludge, compost, etc.) was performed. During isolations experiments, an original isolation procedure was designed using changes in osmotic pressure, the so-called osmoselection. Dozens of promising thermophilic PHA producers were obtained thanks to this original approach. They were taxonomically classified using 16S rRNA and tested for production potential. The most promising PHA producer was the isolate which was classified as Aneurinibacillus sp. H1. This bacterium is able to utilize a variety of substrates, including waste glycerol, to produce PHA. Even more important is the capability of synthesizing copolymers with a high content of 4-hydroxybutyrate. The monomer composition of the PHA copolymer and thus the material properties of the prepared copolymer can be controlled by suitable adjustment of the cultivation conditions. The prepared copolymer P(3HB-co-4HB) has unique properties and the great application potential in numerous high-end applications, for example in the field of health care, food industry or cosmetics.
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Study of biological samples using atomic force microscopy
Khýrová, Markéta ; Smilek, Jiří (referee) ; Slaninová, Eva (advisor)
The purpose of this bachelor thesis was to study Gram-negative bacteria with the ability to accumulate polyhydroxyalkanoates using atomic force microscopy. During the experimental part were studied bacterial strains Cupriavidus necator H16 and its mutant strain Cupriavidus necator PHB-4, Rhodospirillum rubrum, and Halomonas halophila. The main aim was to optimise this microscopy method to study either bacteria in the air or bacteria in liquid medium under physiological conditions. The optimisation was done considering the procedure's simplicity, time demands, and reproducibility. 10× diluted bacterial suspense was dried on a glass surface for measurements in the air. Scanning was performed using TESPA-V2 tip with lowered Spring constant in QITM mode. Various procedures for immobilising bacteria on a glass substrate using Poly-L-lysine and Poly(ethyleneimine) were tested for measurements in liquid. The method using Poly-L-lysine was chosen as the most sufficient way of immobilisation. The tips MLCT – A or SNL – B with the spring constant around 0,1 N/m were applied for measurements in liquid using QITM mode. Finally, an attempt was made to obtain information about the adhesion and Young's modulus of dried and live bacteria concerning the high difference of polyhydroxybutyrate content between the bacterial strains Cupriavidus necator H16 and Cupriavidus necator PHB-4.
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Analytical methods for determination of polyhydroxyalcanoates content in bacterial cells
Černayová, Diana ; Enev, Vojtěch (referee) ; Sedláček, Petr (advisor)
This bachelor thesis deals with methods that are used for determination of polyhydroxyalkanoates (PHA) in cells of bacteria Cupriavidus necator H16. To the applied methods belong Fourier transform infrared spectroscopy, Raman spectoscopy, turbidimetry and thermal analysis (thermogravimetric analysis and differential scanning calorimetry). The results of each method were compared to amount of PHA determinated by gas chromatography. Fourier transform infrared spectroscopy and Raman spectroscopy revealed a linear relation between ratio of characteristic peaks and amount of PHA. FTIR enabled to determine not only the quantitative amount of PHA, but the quality of the sample (cristallinity, amorphous state) as well. Another method was turbidimetry, which has shown correlation between dispersion of UV-VIS light to amount of PHA in bacterial cells. Thermogravimetric analysis was the most effective technique for determination of PHA. The dependence of weight loss of PHA on its content (found by gas chromatography) was determined with the highest accuracy to gas chromatography. Tha last method- DSC was not alternative replacement for quantitative PHA determination. However, DSC indicated crystalline and amorphous state of the polymer.
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Complementary analysis of procaryotic cells by electron microscopy and Raman spectroscopy
Ikrényiová, Terézia ; Sedláček, Petr (referee) ; Hrubanová, Kamila (advisor)
This master thesis deals with conventional methods of bacterial cell analysis, polyhydroxyalkanoates, Raman spectroscopy and electron microscopy in the theoretical part. The production of polyhydroxybutyrate by selected thermophilic bacteria and their analysis by gas chromatography, cryogenic scanning electron microscopy and Raman spectroscopy is described in the experimental part. The chosen sample was analyzed by a transmission electron microscope. Comparing the results from previous mentioned methods it was found that the bacteria Schlegelella thermodepolymerans accumulated the highest amount of PHB. The lowest amount of PHB was obtained by bacteria Rubrobacter xylanophilus. The assumption that the PHB granules formed so-called needle-like plastic deformations during freeze-fracturing was affirmed by cryo-SEM photos analysis. Moreover, it was found that the bacterial cell characterization deduced from microscopic observation of samples corresponded to the description in the literature. TEM provided better resolution photos and in consequence the cells and PHB are more visible. The thesis is also focused on chemical fingerprint analysis of cells by Raman spectroscopy. Several biomolecules were identified by measured Raman spectra for the particular samples.
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Crystallization of microbial polyesters - methods and biological consequences
Liczka, Jan ; Kalina, Michal (referee) ; Sedláček, Petr (advisor)
The aim of this bachelor thesis was to test suitable methods for preparation of amorphous form of microbial polyesters and to perform model experiment to study a kinetics of crystallization of prepared polyesters. The theoretical part deals with PHA characteristics and various methods of isolating PHB granules from bacterial cells. In the experimental part, measuring techniques such as analytical centrifugation, dynamic light scattering (DLS) and Fourier transform infrared spectroscopy (FTIR) were tested to characterize the properties of PHB granules. Furthermore, an experiment was performed to isolate native PHB granules from Cupriavidus necator using lysozyme, deoxyribonuclease and cell disruption by ultrasonification. The results of the analyzes showed that the granules were either isolated amorphous only in the wet and crystallized upon drying, or that the granules were completely amorphous but not isolated from the bacterial cell.
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Stress resistance of bacterial pure cultures and mixed cultures
Chorvátová, Michaela ; Slaninová, Eva (referee) ; Obruča, Stanislav (advisor)
The purpose of this bachelor thesis was to investigate a stress resistance of bacterial monocultures and defined mixed culture. The theoretical part contains a literary review, which deals with the general stress resistance of bacteria and the dynamics of their growth. Furthermore, polyhydroxyalkanoates are introduced, as well as their involvement into stress response of bacteria. In this review was also elaborated the flow cytometry, significant modern method, which was important part of the experiment. In the experimental part, the resistance to osmotic and temperature stress was studied. For this purpose, monocultures of the PHA accumulating strain Cupriavidus necator H16 and the mutant strain Cupriavidus necator H16/PHB-4 unable to accumulate PHA were used. The defined mixed culture was prepared by cocultivating these two strains. Overall, the accumulation and utilization of PHA, namely poly (3-hydroxybutyrate), increased the resistance of bacteria. The most notable was the increase in the case of osmotic stress, when salt concentrations did not significantly reduce the viability of Cupriavidus necator H16 against a mutant strain which viability decreased with growing intensity of stress. On the other hand, experimental temperatures did not have a significant effect on cell viability. The highest growth of bacteria was recorded, in most cases, at their temperature´s optimum of 30 °C.
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Analysis of bacrerial cells employing flow cytometry and flurescence microscopy
Müllerová, Lucie ; Mravec, Filip (referee) ; Obruča, Stanislav (advisor)
This thesis focuses on fluorescent analysis of viability and PHA content in bacterial cultures, the main methods of investigation were flow cytometry and fluorescent microscopy. In order to determine viability of C. necator H16, several viability probes were tested, nevertheless, only BacLightTM kit and propidium iodide can be used to estimate portion of viable and live bacterial cell in samples. Further, Acridine orange was used to monitor physiological state of bacterial culture and two hydrophobic probes, Nile Red and BODIPY 493/503, were used to investigate PHA content in bacterial cells. Application of BODIPY 493/503 seems to be promising since this probe does not require permeabilization of bacteria cells and it can be used along with propidium iodide. Furthermore, several fluorophores were tested in the microscopic part. In was found that concentrations used in cytometric analyses were too high for microscopic use. Emission from the SYTO9 fluorophore is seen mainly in the green channel but because of the high concentration some emission was visible in the red channel. Cells stained with BODIPY 493/503 had very high fluorescence intensities when the stain concentration was 10 . At the same time, negative amplitudes of fluorescence were measured in both strains of C. necator, but in case of C. necator H16 that amplitude was much more pronounced. In this strain surprising high concentration of BODIPY stain was observed on the surface of PHB granules. Anisotropy of the fluorophore was nearing 0 which is very surprising.
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