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PRODUCTION OF BETA-GLUCANS AND OTHER POLYSACCHARIDES BY YEAST AND MICROALGAE
Byrtusová, Dana ; Kráčmar, Stanislav (oponent) ; Kovalčík, Adriána (oponent) ; Márová, Ivana (vedoucí práce)
Beta ()–glucans are polysaccharides composed of D-glucose monomers. Nowadays, -glucans are gaining attention due to their attractive immunomodulatory biological activities, which can be utilized in pharmaceutical or food supplementation industries. Nowadays, the only biotechnological yeast source is Saccharomyces cerevisiae. However, some carotenogenic Basidiomycetes yeasts, previously explored for lipid and carotenoids co-production, could potentially co-produce a significant amount of –glucan. In the present Doctoral Thesis, the culture conditions were optimized for the production of -glucans and other microbial polysaccharides at carotenogenic yeast and microalgae. The genera of Rhodotorula, Sporobolomyces, Cystofilobasidium, and Dioshegia were tested. From non-carotenogenic yeast, the Metschnikowia genera and some ascomycetes yeast were selected together with some green and red algal strains. The experimental part is focused also on the possibility of co-production of other metabolites, like lipids, pigments, and extracellular polymers. In the first part of the experiment, the effect of four C/N ratios (10:1, 40:1, 70:1 and 100:1) on the production of biomass, -glucans, carotenoids, and lipids was evaluated et yeast strains. From all strains, the S. cerevisiae CCY 21-4-102, C. infirmominiatum CCY 17-18-4, P. rhodozyma CCY 77-1-1 and R. kratochvilovae CCY 20-2-26 exhibited the highest -glucans production and were chosen for next analysis, mainly salt stress, temperature, and nitrogen sources in the culture medium. Additionally, R. kratochvilovae CCY 20-2-26 produces extracellular glycolipids and S. pararoseus CCY 19-9-6 extracellular polysaccharides. Next, the diversity of -glucan content among the other twelve Saccharomyces strains and polysaccharides production at microalgae was assessed.
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