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Biotechnological production of yeast metabolites under combined stress
Baťková, Zuzana ; Byrtusová, Dana (referee) ; Dzurendová, Simona (advisor)
This master's thesis focuses on utilizing waste whey for the biotechnological production of carotenogenic yeast biomass and its valuable metabolites such as carotenoids, ubiquinone, ergosterol, fatty acids, and -glucans. Combined stress conditions were used to evaluate the influence on the yeast biomass metabolites production. These metabolites find applications in various industries, for example pharmaceutical, cosmetic, and food. The thesis is divided into theoretical and experimental parts. The theoretical section describes the composition of whey and its valorization in various industries. Selected carotenogenic yeasts and their metabolites are also presented. Furthermore, the impact of nutritional, oxidative stress, and the influence of metals on the production of yeast biomass and metabolites are described. The experimental part is reporting the whey treatment, yeasts biomass production and methods for the determination of individual metabolites. Five strains of red yeasts were used in this thesis: Cystofilobasidium macerans (CCY 10-1-2), Phaffia rhodozyma (CCY 77-1-1), Sporobolomyces shibatanus (CCY 19-9-6), Rhodotorula kratochvilovae (CCY 20-2-26) and Rhodotorula toruloides (CYY 62-2-4). The strain Cystofilobasidium macerans showed the best results for the utilization of whey substrate under the influence of combined stress, especially in biomass, lipid, and -glucan production. A promising strain in carotenoid production under combined stress was Sporobolomyces shibatanus.
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Physiological mechanisms of abiotic stress tolerance in Sorghum bicolor
Kratochvíl, Jan ; Konrádová, Hana (advisor) ; Lhotáková, Zuzana (referee)
Current agriculture is facing a serious challenge of decreasing precipitation and irregular occurrence of drought periods including their unfavorable distribution during the vegetation season. This leads to growing interest in planting highly drought-resistant crops like sorghum. In comparison with other crops, sorghum excels in low water demand, though exhibits high susceptibility to low temperatures, which hampers its spread to new regions. Surprisingly, there is not enough information about the nature of sorghum's reaction to cold exposure. The aim of this diploma thesis was to describe reactions of young sorghum plants exposed to cold stress, low water availability and their combination and to verify the possibility of plant hardening through previous low-stress load. The special focus was paid to changes in carbohydrate metabolism, which plays generally very important role in plant defense reactions. The other analyzed physiological traits were leaf tissue osmotic potential, proline content and basic morphometric characteristics. Experimental design consisted of pot experiments conducted in growth chambers and the experiments performed under controlled conditions in vitro, using two sorghum genotypes "Ruzrok" and "01Z1800012". Both genotypes exhibited similar response to stress treatment....
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Generating a special loading processes
Balda, Miroslav
New computing methods for assessment of fatigue lives of machine parts exposed to combined stress should be tested. With a view to it, fatigue experiments are pursued with predefined periodic processes compounded of deterministic time functions of normal and shear stresses. A straight application of simple functions leads to improper results due to dynamic properties of the testing machine. The contribution describes a way of generating loading processes of much better properties.
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Problems of a limit fatigue stress under combined loading
Balda, Miroslav ; Svoboda, Jaroslav
The theory of fatigue life of structures under combined synchronized harmonic loading has been extended. Limit stress of combined loadding corresponding the fatigue limits has been assembtet from experimental data. They obey both the law of ellipse for in-phaseloading and a bit modified law for out-of-phase loading. A new formula for its exponent has been built.
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