Národní úložiště šedé literatury Nalezeno 1 záznamů.  Hledání trvalo 0.01 vteřin. 
Controlled production of lipids and lipidic substances by selected yeasts and microalgae
Szotkowski, Martin ; Kráčmar, Stanislav (oponent) ; Huelva, Ines Garbayo Nores, University (oponent) ; Márová, Ivana (vedoucí práce)
Carotenoids are natural pigments found in microorganisms such as algae, yeast and cyanobacteria. They represent the most widespread group of antioxidants with a significant biological effect. Currently, there is a growing interest in carotenoids due to their beneficial effects on human health. Chlorophylls are green photosynthetic pigments that are used in the food industry as intensive green dyes. Coenzyme Q is known for its positive effect on the proper functioning of a number of organs in the human body. Ergosterol is an integral part of the membranes of yeasts and fungi. It is a provitamin D2, which is an important part of the immune system. Microbial lipids, or ‚Single cell oils’, are characterised by a high content of healthy unsaturated fatty acids that can be used in pharmacy or cosmetics. Microbial lipids are further studied as an alternative for the production of biofuels. The dissertation focused on the study and possibilities of optimising the production of lipids and lipid substances by selected strains of carotenogenic yeasts, microalgae and cyanobacteria. The tested yeasts of the genera Rhodotorula, Rhodosporidium, Cystofilobasidium and Sporidiobolus were cultivated on a series of different media with different C/N ratios in the range of 13 to 100, containing processed waste substrates of the food industry. Selected strains were then cultivated in bioreactors with medium containing a combination of waste substrates. Cultures of microalgae of the genera Desmodesmus, Scenedesmus, Chlorella, Coccomyxa, Chlamydomonas, Botryococcus dealt with the optimisation of individual components of the medium and the application of various stresses in order to increase the production of the studied metabolites. Pilot large-volume cultures in open tanks were performed as part of experiments with the extremophilic microalgae Cocomyxa. In the final part, pilot screenings and large-volume bioreactor experiments focused on the possibilities of co-cultivation of carotenogenic yeasts and microalgae were performed. The tested yeast strains were able to utilise media containing hydrolysed waste substrates with varying success. The best strain was Sporidiobolus pararoseus, which achieved the highest biomass production and studied metabolites in the media. The tested waste substrates were a combination of waste frying oil and coffee grounds hydrolysate. Successful optimisation of the composition of the mineral medium's main components led to increased production of the studied metabolites. The most important effect exhibited particular P/N ratio and the application of oxidative stress. Desmodesmus and Scenedesmus microalgae achieved the best results. Large-scale cultures of Coccomyxa onubensis confirmed the resistance of the culture to contamination by external influences and the ability to grow at high temperatures and light intensities. Co-cultivation experiments confirmed the ability of symbiotic growth of yeasts and microalgae. The best results were obtained in all tested yeasts co-cultivated with microalgae of the genus Desmodesmus and Scenedesmus and, to a lesser extent, with the genus Coccomyxa.

Chcete být upozorněni, pokud se objeví nové záznamy odpovídající tomuto dotazu?
Přihlásit se k odběru RSS.