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Influence of PHA accumulation on resistance of bacteria against selected antibacterial drugs
Hrabalová, Vendula ; Kučera, Dan (referee) ; Obruča, Stanislav (advisor)
The aim of this bachelor thesis was to study the effect of bactericidal drugs on bacteria from the genus C. necator H16 and its mutant genus PHB-4. The genus H16 shows ability to accumulate polyhydroxyalkanoates (PHA) in the form of granules while the genus PHB-4 lacks to show this ability. The theoretical part of the bachelor thesis is focused on the effect of antibiotics on bacteria in general and the determination of susceptibility of bacteria to antimicrobial substances. The effect of three specific antibiotics (nisine, streptomycin and penicillin) on both bacterial strains was tested in the experimental part. The viability of bacteria was determined by the spread plate method and flow cytometry. Agar diffusion test and broth microdilution test were used to test the susceptibility of bacteria. It was concluded that the accumulation of PHA decreases the tolerance of bacteria to antimicrobial substances because the genus C. necator H16 is more susceptible to streptomycin and penicillin then the strain C. necator PHB-4.
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Stress resistance of PHA accumulating bacteria against conditions associated with gastrointestinal tract
Kovářová, Radka ; Nováčková, Ivana (referee) ; Obruča, Stanislav (advisor)
This bachelor thesis is focused on stress resistance of PHA accumulating bacteria against unfavourable conditions associated with gastrointestinal tract. Two bacterial strains were chosen as model microorganisms for this purpose. Cupriavidus necator H16 producing PHA and its mutant strain Cupriavidus necator PHB-4 without the ability of PHA accumulation. Firstly, three gastrointestinal juices of different concentrations were chosen for the experimental part, namely gastric, bile and pancreatic juices. The stressed bacterial strain was then determined using a spread plate method and a flow cytometry. Other methods used include antimicrobial tests. The agar diffusion method was first tested to determine the size of the inhibition zones. The last method that has been performed is the broth dilution method, which serves to compare the absorbance of pure bacterial suspensions and stressed suspensions with the given juice of a certain concentration. The results show that the production of PHA represents a disadvantage in context of conditions associated with gastrointestinal tract of accumulating bacterial strain.
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Antimicrobial properties of photo-polymerized 3D printed nanocomposites
Matonohová, Zuzana ; Sevriugina, Veronika (referee) ; Lepcio, Petr (advisor)
This diploma thesis deals with the preparation and characterization of nanocomposites suitable for 3D printing by masking stereolithography (MSLA) and emphasis on the antimicrobial properties of prepared nanocomposites. The theoretical part of the work is devoted to research on additive production and 3D printing, materials suitable for 3D printing using the MSLA method and nanocomposites. The experimental part of the work then deals with the preparation of individual composites containing nanoparticles (ZnO, AZO, TiO2 and carbon nanotubes) and their subsequent testing. The printability of the material was monitored by Jacobson working curves and differential scanning photocalorimetry (photo-DSC), then the structure of the composite was evaluated by Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA), mechanical properties were monitored by dynamic-mechanical analysis (DMA) and tensile tests. The main point of this work were antimicrobial tests, which were performed on printed composite samples and on the nanoparticles themselves.
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Production and application of antimicrobial substances produced by lactic acid bacteria
Utíkalová, Kristýna ; Dzurická, Lucia (referee) ; Márová, Ivana (advisor)
The bachelor’s thesis deals with the production of antimicrobial substances by selected lactic acid bacteria of the genera Lactobacillus, Pediococcus and Bifidobacterium, in which the production of bacteriocins was assumed based on the conducted research. Bacteriocins are peptide-based antimicrobial substances with the potential to be widely used primarily as biopreservatives in the food industry. The theoretical part of the bachelor’s thesis focuses on antimicrobial substances produced by probiotic bacteria with a further concentration on bacteriocins produced by selected bacterial species and their current research and application in the industry. In the experimental part, the antimicrobial activity of prepared isolates from probiotic bacteria was tested on selected gram-negative and gram-positive bacteria. Specifically, this was done by the agar diffusion method, the broth dilution method and the cell viability test using resazurin. The amount of lactic acid and acetic acid in the individual isolates was determined using high performance reverse-phase liquid chromatography, which made it possible to further discuss their influence on the antimicrobial activity of the isolates. Strong antimicrobial activity against indicator bacteria was found in all isolates. For some isolates, it was higher than the antimicrobial activity of lactic acid itself together with its concentration which is found in the isolate according to the measurements. That is a significant stimulus for further research of these probiotic isolates, especially the L. acidophilus and L. plantarum isolates. For example, it was found that the tested isolate from L. acidophilus showed an inhibitory activity against S. epidermidis of 90,76 % and 81,62 % against E. coli at a concentration of 20,47 mg/ml. The isolate from L. acidophilus was subsequently applied to plant packaging with the potential of usage in the food industry, and the inhibitory activity of this isolate against contaminating microorganisms was observed.
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Use of some fractions of technical hemp in cosmetics
Gregarová, Lenka ; Hudečková, Helena (referee) ; Márová, Ivana (advisor)
Cannabis sativa is a versatile herb which is known for several thousand years and contains a variety of active substances. This thesis is focused on the use of some extracts of hem in cosmetics, specifically in hair cosmetics. The first part focuses on the Cannabis sativa, introducing the active contained substances and the overall processing of the plant. In the second part were experimentally determined the active substances in five extracts from different varieties, that were supplied from industry. Extracts were compared based on the extraction yield of antioxidants, chlorophylls, phenolic compounds, flavonoids and cannabinoids. Subsequently, a hair shampoo was prepared with the addition of hemp extracts and hemp hydrolysate. Lastly, the inhibitory effect against microorganisms was monitored for extracts and shampoos finally. Beneficial biologically active substances were detected in hemp extracts, wherein higher levels were measured in ethanol extracts. The extracts were also able to inhibit the growth of certain microorganisms. Satisfactory results on hair were observed with the prepared shampoo.
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Antimicrobial properties of photo-polymerized 3D printed nanocomposites
Matonohová, Zuzana ; Sevriugina, Veronika (referee) ; Lepcio, Petr (advisor)
This diploma thesis deals with the preparation and characterization of nanocomposites suitable for 3D printing by masking stereolithography (MSLA) and emphasis on the antimicrobial properties of prepared nanocomposites. The theoretical part of the work is devoted to research on additive production and 3D printing, materials suitable for 3D printing using the MSLA method and nanocomposites. The experimental part of the work then deals with the preparation of individual composites containing nanoparticles (ZnO, AZO, TiO2 and carbon nanotubes) and their subsequent testing. The printability of the material was monitored by Jacobson working curves and differential scanning photocalorimetry (photo-DSC), then the structure of the composite was evaluated by Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA), mechanical properties were monitored by dynamic-mechanical analysis (DMA) and tensile tests. The main point of this work were antimicrobial tests, which were performed on printed composite samples and on the nanoparticles themselves.
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Stress resistance of PHA accumulating bacteria against conditions associated with gastrointestinal tract
Kovářová, Radka ; Nováčková, Ivana (referee) ; Obruča, Stanislav (advisor)
This bachelor thesis is focused on stress resistance of PHA accumulating bacteria against unfavourable conditions associated with gastrointestinal tract. Two bacterial strains were chosen as model microorganisms for this purpose. Cupriavidus necator H16 producing PHA and its mutant strain Cupriavidus necator PHB-4 without the ability of PHA accumulation. Firstly, three gastrointestinal juices of different concentrations were chosen for the experimental part, namely gastric, bile and pancreatic juices. The stressed bacterial strain was then determined using a spread plate method and a flow cytometry. Other methods used include antimicrobial tests. The agar diffusion method was first tested to determine the size of the inhibition zones. The last method that has been performed is the broth dilution method, which serves to compare the absorbance of pure bacterial suspensions and stressed suspensions with the given juice of a certain concentration. The results show that the production of PHA represents a disadvantage in context of conditions associated with gastrointestinal tract of accumulating bacterial strain.
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Influence of PHA accumulation on resistance of bacteria against selected antibacterial drugs
Hrabalová, Vendula ; Kučera, Dan (referee) ; Obruča, Stanislav (advisor)
The aim of this bachelor thesis was to study the effect of bactericidal drugs on bacteria from the genus C. necator H16 and its mutant genus PHB-4. The genus H16 shows ability to accumulate polyhydroxyalkanoates (PHA) in the form of granules while the genus PHB-4 lacks to show this ability. The theoretical part of the bachelor thesis is focused on the effect of antibiotics on bacteria in general and the determination of susceptibility of bacteria to antimicrobial substances. The effect of three specific antibiotics (nisine, streptomycin and penicillin) on both bacterial strains was tested in the experimental part. The viability of bacteria was determined by the spread plate method and flow cytometry. Agar diffusion test and broth microdilution test were used to test the susceptibility of bacteria. It was concluded that the accumulation of PHA decreases the tolerance of bacteria to antimicrobial substances because the genus C. necator H16 is more susceptible to streptomycin and penicillin then the strain C. necator PHB-4.
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