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Biodegradation of bioplasts in compost environment
Vodička, Juraj ; Kovalčík, Adriána (referee) ; Obruča, Stanislav (advisor)
This master’s thesis focuses on biodegradation of polyhydroxybutyrate (PHB) and polylactic acid (PLA). The theoretical part discusses an origin, properties and applications of investigated biopolyesters, and so the enzymology of their biodegradation. The experimental part deals with biodegradation of these polymers in liquid medium using several pure thermophilic bacteial strains and controlled composting of these bioplastics. Amongst six tested thermophilic bacterial strains only one showed PHB-biodegradation activity – strain Schlegelella thermodepolymerans. No degradation degree of amorphous or semi-crystalline PLA was observed. Mainly disintegration of both forms of PLA articles was observed in compost environment, thus the abiotic mechanism of its decomposition was indicated. After 4 weeks of composting, the relative weight loss of 99 % and 63 % was detected in amorphous and semi-crystalline PLA respectively. On the contrary, the weight loss of PHB after 4 weeks of composting reached 36 %, moreover, a half decrease of molar mass was observed using SEC. The surface erosive mechanism of PHB-biodegradation was stated using SEM. By monitoring of esterase, lipase and protease activities, no influence on the compost by polymer presence was concluded at statistical significance.
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In vitro biodegradation of biopolyesters exposed to synthetic gastric juice
Sobková, Markéta ; Skoumalová, Petra (referee) ; Kovalčík, Adriána (advisor)
This bachelor’s thesis is focused on the study of in vitro biodegradation of biopolyesters exposed synthetic gastric juice and phosphate buffer saline with lipase for 81 days. The theoretical part summarises the necessary information about characteristics of biodegradable biopolyesters, deals with their possible applications in medicine. The experimental part deals with the biodegradation of prepared biopolyesters films. in this work, poly(lactic acid), amorphous poly(hydroxy alkanoates), poly(3-hydroxybutyrate), poly(butylene adipate terephthalate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), filament poly(lactic acid) and filament poly(lactic acid)/poly(hydroxybutyrate) were used for the experiment. The films were prepared by dissolving of the biopolyesters in hot chloroform. The dissolving agent was evaporated, and prepared films were dried. Prepared films had different properties depending on the used biopolyesters. Their appearance was formed transparent to milky cloudy. Also, trey differed in their plasticity. During biodegradation, the morphology changed, and the samples gained higher fragility. The effect of biodegradation was monitored by changes in 1) molecular weights (SEC-MALLS), 2) chemical structure (FTIR) and 3) weight loss changes (gravimetrically). The analysed biopolyesters were demonstrably susceptible to biodegradation in simulated body conditions. The degree of biodegradation depends on the type of biopolyester. The most significant weight loss was recorded for the sample of amorphous polyhydroxyalkanoate (PHA). The PHA´original weight was reduced about 84.28 ± 0.03 % after the 81 days of biodegradation in the phosphate-buffered saline with lipase.
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Study of Whey Biodegradation by thermophilic Bacteria
Fischerová, Lenka ; Vránová, Dana (referee) ; Babák, Libor (advisor)
This thesis deals with the possibilities of biodegradation of whey by the means of a mixed thermophilic aerobic bacterial culture of the Bacillus and Thermus genera. After protein had been removed, the whey was used as a medium for cultivation of the thermophilic microorganisms. The cultivations took their course in a fermentation unit and in the Erlenmayer flasks in a heated shaker in a whey medium. The bioengineering characteristics of the cultivation processes and the degree of biodegradation of the whey were evaluated. Scale of the whey biodegration was judged through the analytical characteristics – concentration of biomass, laktose and a chemical oxygen demand (COD). A decrease of CHSK was detected in all cultivations. Maximal reduction of CHSK was happend always in c. first half of each exponential phase growt, i.e. about 15 ± 3 % after first growth phase and sumarily about 62 ± 4 % after second growth phase.
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Processing optimalization of biodegradable starch based packaging and its characterization for adaptation on production technology
Krahulová, Veronika ; Ondreáš, František (referee) ; Lepcio, Petr (advisor)
This diploma thesis focuses on the problematics of preparation of biodegradable starch based packaging. The aim of the thesis is to optimize the preparation and verify the characteristics for further adaptation and production technologies. The films consisted of starch, PVA and glycerol. Four types of starches, three types of PVA and different ratios of glycerol were tested. Films were prepared by casting with glycerol as a plasticizer, instead of distilled water, to reduce the energy cost of the preparation. The mechanical properties of the films were tested as well. The experimentally determined values of elongation at break and tensile strength of the wheat starch films were compared with a semiempirical model. Results revealed that the preparation of thermoplasticization of starch with glycerol leads to a considerable increase in elongation at break but at the same time to a marked decrease in tensile strength compared to the preparation from solution. The rheological properties of the prepared films were also investigated. Infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used to study the structure of the films.
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Application of thermophilic Culture for Organic Compounds Biodegradation
Piechová, Jana ; Burdychová, Radka (referee) ; Babák, Libor (advisor)
The aim of this work is focused on biodegradability study of modified polyurethane materials (foams and foils) in glukose medium and biodegradation of whey. The biodegradability was tested with using mixed thermophilic aerobic bacterial culture of the Bacillus and Thermus genera. The cultivations were practised in the fermentor and in Erlenmayer flasks in a heated shaker. Maximal reduction of COD and culture growth has been achieved by biodegradation of polyuretane in the fermentor. Main effect of degradation was abiotic destruction of PUR materials and consequent utilization of degradation products by bacterial culture. These tests indicated that the best modification agent for biodegradation was 10% carboxymethyl cellulose. The polyurethane foam was more decomposed then the polyurethane foil. Biodegradation of whey without proteins in the fermentor was detected decrease of CHSK and lactose concentration about 50 % in 20th hour. Optimal conditions for whey biodegradation with the thermophilic bacterial culture were pH 6,5 and temperature 60 °C.
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Study on biotechnological potential of thermophilic gram-positive bacterium Brevibacillus sp. Bz
Filimonova, Anastasiia ; Obruča, Stanislav (referee) ; Pernicová, Iva (advisor)
Předmětem předložené diplomové práce je studium biotechnologického potenciálu termofilní grampozitivní bakterie Brevibacillus borstelensis BZ. Teoretická část obsahuje obecnou charakterizaci termofilních organismů a jejich termozymů. Popisuje také adaptivní molekulární mechanismy, které zajišťují termostabilitu těchto proteinů. Závěr teoretické části je věnován biodegradaci odpadních substrátů a polymerů na bázi přírodních a fosilních zdrojů. První část experimentální práce se zabývá produkcí hydrolytických enzymů na různých původních zdrojích a odpadních substrátech. Díky intenzivní enzymatické produkci na původních zdrojích je Brevibacillus borstelensis BZ považován za velmi slibného producenta termostabilních enzymů, konkrétně xylanáz a celuláz. Testovaný bakteriální kmen BZ byl schopen produkce termostabilních enzymů i na odpadních substrátech. Na vybraných substrátech kmen BZ přednostně produkoval xylanázy. Díky tomu byla xylanázám věnována zvláštní pozornost, kdy bylo testováno teplotní a pH optimum. Závěrem experimentální práce byla testována schopnost bakterie Brevibacillus borstelensis BZ degradovat vybrané polymery na bázi přírodních a fosilních zdrojů. Kmen BZ poskytl nový pohled na biologický rozklad polyethylentereftalátu (PET), amorfní frakce kyseliny polymléčné (PLA), semikrystalické PLA a polyhydroxyalkanoátů (PHA). Pozorováním povrchu PET fólie skenovacím elektronovým mikroskopem (SEM) se potvrdilo zdrsnění materiálu, přítomnost rýh a naprosté pronikání bakterie skrz fólii. Pokud jde o polymery na bázi přírodních zdrojů, PHA granule byly zcela degradovány. Studiem morfologie povrchu obou zmíněných PLA bylo prokázáno jasné zhoršení jejich struktury přítomností jam a trhlin na povrchu polymerů.
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Influence of biodegradation of polyhydroxyalkanoates on soil properties and composition
Denková, Pavla ; Doležalová Weissmannová, Helena (referee) ; Kučerík, Jiří (advisor)
Biodegradable plastics are presented as a promising replacement for synthetic polymers. In soil, they are expected to be fully degraded by micro-organisms within a short time and to be inherently harmless to the environment. However, this assumption needs to be verified, and it is important to pay attention to the impact on soil´s biota as well as the effect of the biodegradation process could have on soil properties, composition and structure. In this work was studied the effect of biodegradation of poly(R-3-hydroxybutyrate), (P3HB), belonging to the group of polyhydroxyalkanoates, on the structure and physicochemical properties of soil. P3HB particles were mixed in different concentrations with soil in which biodegradation experiments were carried out under different conditions - i.e. with and without growing plant, with and without nitrogen fertilization. After 90 days, were soil analyzed. Thermogravimetry was used to determine the amount of residual non-degraded micro-bioplastics and to determine the effect of biodegradation on the properties of soil organic matter. Differential scanning calorimetry provided information on the effect of biodegradation on the evaporation enthalpy of adsorbed water from the soil, while the amount of water in the soil was also determined. Furthermore, the effect on field water holding capacity was determined and sieve analysis of individual samples was performed to characterize the effect of biodegradation on soil particle size distribution. Biodegradation conditions were shown to affect not only the rate of biodegradation but also some soil parameters. As expected, biodegradation of P3HB was proved to be faster in a nutrient-rich environment. In contrast, lack of nitrogen in soil with growing plant caused a decrease in the evaporation enthalpy of water and a reduction in the amount of water in soil, which can lead to easier soil drying and cause stress conditions for plant growth. Increased soil particle aggregation was observed in all sample series with P3HB compared to soils without P3HB addition.
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Kompostování bioplastů
Kořínková, Aneta
The final work deals with research on the behaviour of various bioplastic materials placed in composting base under laboratory conditions and subsequent assessment of the phytotoxic effects of individual composts. Composting was carried out on the basis of modified standard ČSN EN 14045 and knowledge from standard ČSN EN 14046. The determination of chronic phytotoxic effects followed the modified standard ČSN EN 13432 and acute phytotoxicity was assessed using the Phytotoxkit test. Following completion of the composting process, decomposition was observed for the certified vegetable starch-based sample, two other samples without certification, but marked as 100% degradable, showed no evidence of decomposition. Various indicator organism growth inhibition values were observed, with chronic toxicity testing in the range of 3.4-20.9%, and phytotoxkit testing two of the samples showed a stimulating effect. Different bioplastic materials have achieved different results and represent a different level of potential environmental burden.
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Biodegradace azobarviv působením hub bílé hniloby
Bírošíková, Paulína
White rot fungi, belonging to wood decay fungi have the ability to degra-de complex aromatic structures such as lignin or pollutants with an aromatic structure (tetracyclines, endocrine disruptors) via extracellular ligninolytic enzymes. Azo dyes are synthetic dyes containing aromatic rings with bonded substituents lin-ked by an azo group. Fungi are able to degrade these structures, whereas decrease of dye is observed, called decolorization. The aim of this bachelor's thesis is to de-termine the degradation ability of three types of azo dyes (methylene red, tartrazine and azorubin) using ten types of white rot fungi. Cultivation of individual fungi with the dyes was carried out for twenty-four days, during which the absorbance was monitored using a UV/VIS spectrophotometer at intervals of every other working day. The colour loss was calculated from the measured values and the decoloriza-tion values were expressed graphically as a percentages. The selected fungi showed the greatest decolorization of tartrazine on the second day of the experiment, an average of 89%, except for the fungus Fomes fomentarius, for which dye decoloriza-tion was not observed. In contrast, the least degraded dye was azorubin, an average of 37% at the end of the experiment for most fungi species. Methylene red showed the most stable decolorization trend, with an average of 77% at the end of the me-asurement. The effect of decolorization was influenced by the structure of the azo dyes and the efficiency of specific fungal species.
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