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Controlled Production and Degradation of Selected Biomaterials
Obruča, Stanislav ; Demnerová, Kateřina (oponent) ; Vávrová, Milada (oponent) ; Němec, Miroslav (oponent) ; Márová, Ivana (vedoucí práce)
Proposed dissertation thesis is aimed at the study of production and degradation of polymeric materials using microorganisms. The main attention is given to polyesters of bacterial origin - polyhydroxyalkanoates. These materials are accumulated by a wide variety of bacterial strains which use polyhydroxyalkanoates as a storage of carbon, energy and reducing power. Thanks to their mechanical properties, that are similar to those of traditional synthetic plastics such as polyethelene or polypropylene, and thanks to their biodegradability, polyhydroxyalkanoates are considered to be environmental-friendly alternative to traditional plastics of petrochemical origin. Thus, polyhydroxyalkanoates have many potential applications in industry, agriculture as well as in medicine. Important part of this thesis is focused on production of polyhydroxyalknotes from waste substrates coming from food industry. Among tested substrates was waste cheese whey or waste plant edible oils of different origin. Utilization of cheap waste substrates for polyhydroxyalkanoates production could facilitate economically feasible process of large scale production of polyhydroxyalkanoates. According to the results presented in this thesis, waste oils are very promising substrates for biotechnological production of polyhydroxyalkanoates. Next part of the thesis deals with involvement of polyhydroxyalkanoates into stress response of bacteria. It was observed, that exposition of bacterial culture to controlled dose of ethanol or hydrogen peroxide resulted in significantly enhanced yields (abut 30 %). After stress factors application, particular metabolic pathways involved in stress response were activated in order to endure stress conditions. Subsequently, NAD(P)H/NAD(P)+ ratio increased and, thus, Krebs cycle was partially inhibited whereas polyhydroxyalkanoates synthetic pathway was activated. Moreover, application of stress factors increased molecular weights of polymers. Therefore, strategy based on application of controlled dose of stress not only enhanced polymer yields, but, moreover, improved properties of materials. The last part of thesis describes the investigation of biodegradation of polyurethane elastomeric films modified by various biopolymers in presence of mixed thermophillic culture as a model of natural bacterial consortium. The presence of materials in cultivation medium resulted in delayed but intensive growth of bacterial culture. The unusually long lag-phase was caused by release of un-reacted polyether polyol and tin catalyst from materials. The main part of material degradation was caused by abiotic degradation of elastomeric films, nevertheless, also bacterial culture slightly contributed to material decomposition. The measure of biotic degradation strongly depended on type of used modification agent. The highest tendency to undergo biotic degradation was observed for elastomeric film modified by acetylated cellulose.
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Influence of bioplastics´ biodegradation on soil quality
Paluchová, Natálie ; Doležalová Weissmannová, Helena (oponent) ; Kučerík, Jiří (vedoucí práce)
Over the past decade, the society has brought attention to microplastics. They are produced by various industries and spread across the environment. For long time, they were considered inert, without further effect on plants and any other living organisms, however as recent studies found out, they might be a serious threat. Therefore, several researchers, including us, begun to focus on their transport and transformation in the environment. Most of the researchers, however, focus only on their presence in the marine and fresh waters and hence their behaviour in air and soil remains rather unclear. Furthermore, bioplastics has been brought to the media spotlight. They are presented as an ecological alternative to solve all the problems mentioned so far (and more). But what is often forgotten, their main advantage might also be their bottleneck. For that reason, this master's thesis focuses on negative effects associated with the presence of microplastics (specifically poly-(R)-3-hydroxybutyrate bioplastic) in soils as their common receptor. We combined respirometry, elemental analysis, thermogravimetry and enzymatic assays to investigate physico-chemical changes in soil induced by the presence of the bioplastic. Our results showed a negative effect on soil organic matter and water retention in the soil. In this sense, priming effect was widely investigated as acceleration and also retardation of soil organic matter decomposition took place. We registered different influence of selected concentrations of biopolymer on the soil and also the influence of soil properties on the course of degradation. Last but not lest, increased enzymatic activities clearly suggested impact of biopolymer presence on the microbial community. Such findings let us conclude, that biopolymer addition leads to long-term impact on a range of soil ecosystem services.
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Možnosti odbourávání syntetických makromolekulárních látek se zaměřením na biodegradace
Zichová, Miroslava ; Ondruška, Vladimír (oponent) ; Babák, Libor (vedoucí práce)
Tato práce se zabývá možnostmi odbourávání syntetických makromolekulárních látek. Je zde popsána degradace mechanická, chemická a fyzikálně-chemická, práce se však zaměřuje hlavně na biodegradaci. Biodegradace polymeru je jeho rozklad pomocí mikroorganismů. Cílem této práce je poukázat na výhody biodegradace oproti jiným degradačním metodám a dále uspořádat získané poznatky o biodegradaci konkrétních makromolekulárních látek. Jsou zde shrnuty poznatky o degradaci polyuretanů tvořících výjimku mezi syntetickými polymery, které jsou většinou odolné vůči biodegradaci. Pozornost je také věnována plastům se zkrácenou životností.
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Studium biodegradace polyhydroxyalkanoátů.
Wurstová, Agáta ; Přikryl, Radek (oponent) ; Obruča, Stanislav (vedoucí práce)
Diplomová práce je zaměřena na studium biodegradace polyhydroxyalkanoátů, konkrétně polymeru polyhydroxybutyrátu. První část práce se zabývá studiem biodegradace polyhydroxybutyrátu ve formě PHB prášku a PHB fólie pomocí vybraných druhů mikroorganismů z řad bakterií, kvasinek a plísní. Jako zástupce bakterií byl vybrán mikroorganismus Delftia acidovorans, z řad kvasinek Aureobasidium pullulans a ze zástupců plísní Aspergillus fumigatus. Aktivita extracelulární PHB depolymerázy byla analyzována turbidemitrickým měřením suspenze PHB granulí. Zároveň byla stanovena hodnota pH a teplotního optima jednotlivých PHB depolymeráz. Z výsledků vyplývá, že bakterie D. acidovorans dokáže částečně degradovat PHB, naopak kvasinka A. pullulans nedokáže PHB účinně degradovat. Nejvýraznější degradační schopnost vykazovala plíseň A. fumigatus, která PHB kompletně degradovala v rámci daného testu. Extracelulární enzymy exprimované těmito mikroorganismy při kultivaci na PHB jako jediném zdroji uhlíku byly analyzovány pomocí SDS-PAGE. Druhá část práce se zabývá biodegradací PHB ve formě PHB fólie, PHB tvrzené fólie a PHB Nanoul textilie v rámci standardního kompostovacího testu. Polosuchá kultivace podávala pozitivní výsledky, kdy v intervalu od 14. dnů do dvou měsíců byly zcela biodegradovány všechny formy použitých PHB. Co se týče polosuché kultivace, byla touto metodou ještě studována míra biodegradace polyuretanových elastomerů, kde část polyesterového polyolu byla nahrazena PHB (PU-PHB). Testovány byly vzorky obsahující komerční PHB od firmy Sigma a vzorky s PHB připravené na Fakultě chemické VUT v Brně. Jednotlivé vzorky se navíc lišily rozdílnou koncentrací dispergovaného PHB (1 %, 5 % a 10 %) v polyuretanu. Na konci kultivace, která trvala dva měsíce, byly zjišťovány mechanické změny materiálu v tahu, účinnost biodegradace vážkovou analýzou a změna povrchu materiálu analýzou mikroskopickou.
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Kostní implantáty na bázi železa
Hávová, Mariana ; Vondrák, Jiří (oponent) ; Sedlaříková, Marie (vedoucí práce)
Předkládaná diplomová práce se zabývá biodegradabilními materiály na bázi železa a možnostmi jejich využití v medicíně. Konkrétně se soustředí na jejich aplikaci jako dočasných kostních implantátů. Práce dále stručně shrnuje obecné použití biomateriálů v medicíně a více se věnuje problematice biodegradabilních materiálů a rychlosti jejich koroze v organismu. Praktická část předkládá metodiku zvolenou pro přípravu železných porézních materiálů s příměsí křemíku. Struktura připravených vzorků je určena pomocí EDX a XRD analýzy. Vliv příměsi křemíku na korozní chování vzorků je sledován při imerzním testu ve třech roztocích simulujících tělní tekutiny. Dále je korozní odolnost analyzována pomocí elektrochemických zkoušek, z nichž jsou získány potenciodynamické křivky pro určení korozního potenciálu a korozní proudové hustoty.
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Biodegradabilní kostní implantáty na bázi železa
Müller, Petr ; Kazda, Tomáš (oponent) ; Sedlaříková, Marie (vedoucí práce)
Osteosynthesis, temporary bone replacement, biodegradable metals, biodegradation, biocompatibility, powder metallurgy, sintering, iron, ferrous alloys, electrochemical corrosion, corrosion potential, spectroscopy
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Biodegradabilní kostní implantáty na bázi železa
Hrabovský, Jan ; Zatloukal, Miroslav (oponent) ; Sedlaříková, Marie (vedoucí práce)
Tato práce pojednává o aktuálním tématu, kterým jsou biodegradabilní kostní implantáty. Tyto materiály mohou být vhodný kandidát pro dočasné dlahy, přičemž dochází k jejich pozvolnému rozkladu. Důležitým parametrem jsou nejen mechanické vlastnosti, tak aby materiál odolal zatížení, ale především korozní vlastnosti a proces degradace. V této práci je seznámení s fyziologií kosti, stopovými prvky a jsou také popsány aktuální trendy v oblasti implantátů. Poslední část tvoří teoretický úvod do korozních procesů. Praktická část je zaměřená na přípravu vzorků na bázi železa s různými dopanty, jejich žíhání a analýzy.
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Modification of polyurethane by biodegradable poly(hydroxybutyrate)
Kupka, Vojtěch ; Žídek, Jan (oponent) ; Vojtová, Lucy (vedoucí práce)
The aim of the presented bachelor thesis was the synthesis of elastomeric polyurethane filled by biodegradable polyhydroxybutyrate. The morphology of samples was analyzed by scanning electron microscopy and mechanical properties were tested by tensile measurement. Moreover, the work deals with prediction of mechanical properties based on rubber elasticity theory. It was found that prepared specimens have a character of particle – reinforced composite materials. Corresponding to divination, the biodegradable filler content enhancement in polyurethane matrix leaded to an increase of the elastic modulus. Prediction of stress-strain curves, which was done by SEC.exe software, showed for real behavior of stress-strain curve having unreal values of network density of polymer chains. While real values of chains network density were used in simulation, stress-strain data were higher than the measured ones.
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Microbial Degradation of Polycaprolactone-based Materials
Damborský, Pavel ; Stratilová, Eva (oponent) ; Hermanová, Soňa (vedoucí práce)
The thesis deals with the issue of the effect of nutritious factors and aeration on Bacillus subtilis (CCM 1999) lipase production, which was studied from the viewpoint of the crucial action of lipases on polyester chains degradation. The parameters such as bacterial growth, lipolytic activity, pH optimum, temperature optimum, thermal stability, proteolytic activity, the amount of proteins, etc. were determined in three types of media inoculated by Bacillus subtilis. One sample set of media: peptone and yeast extract (NB), medium consisted in peptone and yeast extract with the addition of 2% (w/v) glucose (NBG) and mineral solution with yeast extract (MS-YE) contained poly(-caprolactone), PCL film (Mn = 10 kDa, = 1.4). Experiments were performed for 21 days under shaking at 160 and 200 rpm. The presence of PCL caused in both types of media (NB, NBG) higher values of lipolytic activity of Bacillus subtilis indicating the participation of released low-molecular weight species as the products of PCL biodegradation. In BS-inoculated MS-YE medium low lipolytic activity of Bacillus subtilis as compared with those measured in NB and NBG media was determined even in the presence of PCL. During experiment pH value shifted from neutral (pH 7.0) to alkaline (pH 8.5 – 9.3) region for all types of media with and without PCL specimens. This fact indicates negligible pH changes in microenvironment due to the degradation products and/or metabolites. Lipolytic enzymes determined in supernatants free of bacterial cells have shown two pH optima in the presence of PCL, at pH 7 and 9. Lipase in the absence of polymer displayed optimum pH of 7. Measurement of thermal stability demonstrated that extracellular lipases as relative thermostable enzyme especially in the absence of polymer. The basic proteomic analysis by peptide mass fingerprint (PMF) of lipases produced by Bacillus subtilis at NBG medium after one week of cultivation was performed. The presence of proteins with molecular weight (19.3 kDa) close to that reported for lipases was verified through FPLC. Both SDS-PAGE and IEF-PAGE indicated presence of these proteins in both studied media (NBG vs. NBG/PCL). However, no differences have been found in the presence of PCL and no lipase was truly identified through MALDI-TOF mass spectrometry. The occurrence of degradation process in PCL samples was also documented by their gradual weight loss, which was seen in all media types as the synergic effect of lipase- and base-catalyzed ester bond scission. Model degradation study of PCL and its composite with graphene oxide (2.7 wt% GO) was performed in the presence of Bacillus subtilis in NBG medium at 30 °C and initial pH 7 for three weeks. The weight loss of PCL films gradually increased during whole degradation test up to 12 wt%. Degradation of PCL/GO composite proceeds slower as documented by maximum weight loss of 5.0 wt%. The similar character of elution curves of both PCL and its composite, determined by SEC analysis, indicated shifting to lower molecular region.
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