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Elektrochemická charakterizace bioelektronických systémů
Runštuková, Nikola ; Salyk, Ota (oponent) ; Ehlich, Jiří (vedoucí práce)
Cílem této práce bylo elektrochemicky charakterizovat platformu 24 palivových článků pro velkoobjemový screening elektrogenních mikroorganismů a porovnat distribuci naměřených hodnot mezi jednotlivými články. V teoretické části se práce zabývá popisem elektrogenních bakterií, které jsou klíčové pro produkci proudu v mikrobiálních palivových článcích, popisem mikrobiálních palivových článků a metodami vhodnými k jejich charakterizaci. V experimentální části je uveden postup sestavení platformy včetně postupů měření. Výsledkem práce je charakterizace platformy před inokulací a po inokulaci pomocí měření napětí naprázdno, kontinuálního měření proudu, cyklické voltametrie, lineární voltametrie a elektrochemické impedanční spektroskopie. Díky těmto metodám byly zjištěny hodnoty napětí naprázdno, maximálního výkonu a vnitřního odporu a následně byly porovnány z hlediska distribuce těchto hodnot v rámci všech palivových článků. Provedenými experimenty tak byla ověřena správná funkce palivových článků.
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Production of Selected Microbial Metabolites and Energy Using Different Waste Materials
Petrik, Siniša ; Rychtera, Mojmír (oponent) ; Němec, Miroslav (oponent) ; Pekař, Miloslav (oponent) ; Márová, Ivana (vedoucí práce)
Wide spectrum of different options available for the treatment and management of waste substrates can be used. Variety of methods and technologies available to carry out material and energy recovery originates a number of “recovery paths”. One of the solutions for recovering some waste materials lies in white (or industrial) biotechnology, which involves metabolic activities of a wide range of different microorganisms and their specific biological conversion. In this work several waste materials (mainly obtained from agro-industry) were used in a comparative screening study to evaluate their potential recovery to a valuable metabolites or energy by various microorganisms applied under specific conditions and circumstances. Presented study was focused on a comparison of growth and production properties of several red yeast strains of the genus Rhodotorula, Sporobolomyces and Cystofilobasidium, when cultivated on glycerol media (technical and waste glycerol), on wheat straw media and residues gained after hydrothermal pretreatment and on media enriched with whey. All tested red yeast strains were able to utilize glycerol as the only carbon source. The biomass production, when cultivated on pure technical glycerol, are less or more equal with control (about 7 - 10 gl-1) while in waste glycerolis even higher (10.9 - 14.5 gl-1).Production of carotenoids and ergosterol was better in glucose medium than in medium with glycerol only. All tested red yeast strains were able to produce also neutral lipids, in range of 11–15 % except C.capitatum, which produced more than 22 % of neutral lipids. Further waste products - both fraction after hydrothermal wheat pretreatment process (filter cake and hydrolysate) and untreated wheat straw were utilized for red yeast cultivation. Wheat straw (as well as pretreated materials) has proved to be promise substrate with a bigger potential for biomass and metabolite production, especially in S. roseus strain. Whey, as a surplus product from dairy, can be effectively utilized by synergic activities of carotenogenic yeasts and lactic acid bacteria. Co-cultivation process could lead to overproduction of pigments and ergosterol and, therefore, obtained biomass (enriched also with L. casei bacteria) will increase overall quality. In this thesis, the operating microbe which shall be involved in the process of energy recovery represents a mixture of bacteria obtained from the waste water plant. Those microbes played main role in Microbial Fuel Cell (MFC), producing electrical energy and cleaning waste water at once. Electricity is being generated in a direct way from organic matter and can be used for operation of the waste treatment plant, or sold to the energy market.
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Novel Devices and Materials for Bioelectronics
Ehlich, Jiří ; Achilleas Savva, Ph.D (oponent) ; Cifra,, Michal (oponent) ; Salyk, Ota (vedoucí práce)
This dissertation represents a synthesis of projects I have been working on in the course of my Ph.D. studies. The projects evolve around a wide range of topics, which is the reason for the broad and general title. Projects described it the thesis involve the development of electronic tools which can be applied to several areas of bioelectronics: The first part of the thesis concerns platforms for the study of unique microorganisms capable of direct electron exchange with electronic devices. This involved design, fabrication, and application of such platforms. The second part of the thesis deals with electrical stimulation; its application to stem cells towards their directed differentiation, and fundamental studies of possibly harmful irreversible faradaic reactions happening in the course of broadly used electrical stimulation protocols applied in clinical practice. All the projects share core, common, theoretical, and practical foundation originating in chemical engineering, electrochemistry, and materials science. A unifying feature playing a major factor and appearing throughout all the projects would be a family of oxygen reduction reactions. Oxygen reduction is a necessary half-cell reaction taking place in the developed device studying electroactive microorganisms. Oxygen reduction and subsequent generation of reactive oxygen species might arguably play a significant role in the direct electrical stimulation of stem cells towards their differentiation. Lastly, oxygen reduction reactions were the main irreversible faradaic reactions we have been observing during standard electrical stimulation protocols. The thesis presents summarized theoretical background necessary to understand presented projects. Goals are defined. Results are introduced as a commented list of published scientific publications. Achieved outcomes are summarized and discussed. Also, a perspective into the future is given. Main results can be summarized as follows. First goal was to develop a platform for electrochemical characterization of electroactive microorganisms. The platform was based on 24 or 96-well Microbial Fuel Cell array. After two design iterations a prototype fulfilling all the intended requirements was developed, tested, and proven to be reliably working. Next, a multi-well platform of interdigitated electrodes was fabricated and used for electrical stimulation of stem cells. Unfortunately, the platform turned out to be unreliable and not working properly which resulted in the failed attempt to differentiate stem cells into a specific type of cells. Lastly, we have examined oxygen reduction reactions (ORRs) on electrodes made of typical materials used for neural stimulation electrodes. Oxygen can be reduced either to water or hydrogen peroxide. Both reactions can significantly reduce the quantity of dissolved oxygen near the electrode, creating hypoxic conditions harmful to neurons. Peroxide, meanwhile, can induce toxic reactions or act as a signaling molecule. We have examined the amount of reduced oxygen and produced peroxide by various stimulation protocols using amperometric sensors and compared electro-catalytic activities of studied materials. Main finding is that typical protocols lead to irreversible ORRs. Some electrode materials induce highly hypoxic conditions, others additionally produce hydrogen peroxide into the mM range.
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Elektrochemická charakterizace bioelektronických systémů
Runštuková, Nikola ; Salyk, Ota (oponent) ; Ehlich, Jiří (vedoucí práce)
Cílem této práce bylo elektrochemicky charakterizovat platformu 24 palivových článků pro velkoobjemový screening elektrogenních mikroorganismů a porovnat distribuci naměřených hodnot mezi jednotlivými články. V teoretické části se práce zabývá popisem elektrogenních bakterií, které jsou klíčové pro produkci proudu v mikrobiálních palivových článcích, popisem mikrobiálních palivových článků a metodami vhodnými k jejich charakterizaci. V experimentální části je uveden postup sestavení platformy včetně postupů měření. Výsledkem práce je charakterizace platformy před inokulací a po inokulaci pomocí měření napětí naprázdno, kontinuálního měření proudu, cyklické voltametrie, lineární voltametrie a elektrochemické impedanční spektroskopie. Díky těmto metodám byly zjištěny hodnoty napětí naprázdno, maximálního výkonu a vnitřního odporu a následně byly porovnány z hlediska distribuce těchto hodnot v rámci všech palivových článků. Provedenými experimenty tak byla ověřena správná funkce palivových článků.
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Production of Selected Microbial Metabolites and Energy Using Different Waste Materials
Petrik, Siniša ; Rychtera, Mojmír (oponent) ; Němec, Miroslav (oponent) ; Pekař, Miloslav (oponent) ; Márová, Ivana (vedoucí práce)
Wide spectrum of different options available for the treatment and management of waste substrates can be used. Variety of methods and technologies available to carry out material and energy recovery originates a number of “recovery paths”. One of the solutions for recovering some waste materials lies in white (or industrial) biotechnology, which involves metabolic activities of a wide range of different microorganisms and their specific biological conversion. In this work several waste materials (mainly obtained from agro-industry) were used in a comparative screening study to evaluate their potential recovery to a valuable metabolites or energy by various microorganisms applied under specific conditions and circumstances. Presented study was focused on a comparison of growth and production properties of several red yeast strains of the genus Rhodotorula, Sporobolomyces and Cystofilobasidium, when cultivated on glycerol media (technical and waste glycerol), on wheat straw media and residues gained after hydrothermal pretreatment and on media enriched with whey. All tested red yeast strains were able to utilize glycerol as the only carbon source. The biomass production, when cultivated on pure technical glycerol, are less or more equal with control (about 7 - 10 gl-1) while in waste glycerolis even higher (10.9 - 14.5 gl-1).Production of carotenoids and ergosterol was better in glucose medium than in medium with glycerol only. All tested red yeast strains were able to produce also neutral lipids, in range of 11–15 % except C.capitatum, which produced more than 22 % of neutral lipids. Further waste products - both fraction after hydrothermal wheat pretreatment process (filter cake and hydrolysate) and untreated wheat straw were utilized for red yeast cultivation. Wheat straw (as well as pretreated materials) has proved to be promise substrate with a bigger potential for biomass and metabolite production, especially in S. roseus strain. Whey, as a surplus product from dairy, can be effectively utilized by synergic activities of carotenogenic yeasts and lactic acid bacteria. Co-cultivation process could lead to overproduction of pigments and ergosterol and, therefore, obtained biomass (enriched also with L. casei bacteria) will increase overall quality. In this thesis, the operating microbe which shall be involved in the process of energy recovery represents a mixture of bacteria obtained from the waste water plant. Those microbes played main role in Microbial Fuel Cell (MFC), producing electrical energy and cleaning waste water at once. Electricity is being generated in a direct way from organic matter and can be used for operation of the waste treatment plant, or sold to the energy market.
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