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Influence of some microbiogenic elements on carotenogenic yeasts
Pulkrábek, Josef ; Holub, Jiří (referee) ; Obračaj, Jan (advisor)
Carotenogenic yeasts of the genus Rhodotorula are well known for their production of a variety of economically valuable and otherwise difficult to produce compounds such as fatty acids, carotenoids, ergosterol, and ubiquinone. This study investigates the effect of the addition of select microbiogenic elements (Fe, Se, I) and their combinations into mineral cultivation media on the production of the mentioned valuable metabolic products and the rate of element sorption into the biomass of the strains of Rhodotorula mucilaginosa, Rhodotorula kratochvilovae, and Rhodotorula toruloides. Additionally, the sorption of zinc oxide, ferrous fumarate, and selenomethionine into previously cultivated biomass was measured with sorption times of 2 and 24 hours. Fatty acid content was determined using GC-FID, while carotenoids, ergosterol, and ubiquinone were analyzed using HPLC-DAD, with element content being quantified using ICP-OES and IC. With a few exceptions, the production of metabolic products was decreased with the addition of elements into the media and inversely correlated with their concentration. Higher concentrations generally showed greater absolute amounts of sorbed elements but lower relative amounts, which, combined with reduced production of metabolic products shows that the media are not ideal for the cultivation of the given species. The elemental contents were such that biomass supplemented with individually sorbed elements would vaguely align with ESFA dietary reference values, but cultivation in media with a mixture of added elements could result in the biomass containing either insufficient iron or excessively high levels of selenium. Sorption levels were relatively low (5 to 22 % for iron and 0.5 to 2.5 % for selenium). Indicating that cultivation in media with lower concentrations of elemental additives is a promising area for future research.
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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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