The master’s thesis focused on the production of extracellular polysaccharides by selected yeast strains
and their use in the preparation of polysaccharide particles for the encapsulation of model antioxidants.
In the experimental part, the strains Cystofilobasidium macerans, Phaffia rhodozyma, Sporidiobolus
pararoseus, and Rhodotorula mucilaginosa were cultured. The highest production of extracellular
polymers was recorded for the P. rhodozyma strain (4.9±0.2) g/l, and these biopolymers were further
subjected to structural analysis by FTIR-ATR and Alcian blue staining. The results showed that these
are heteropolysaccharides composed of mannan and glucan units with the presence of uronic acids and
mannoprotein complexes. Prebiotic activity was demonstrated in all exopolysaccharides tested. For the
purification of exopolysaccharides, the most effective method of deproteinization using tannic acid was
established.
Stable polysaccharide particles were prepared using the polyelectrolyte complexation method.
A 0.1% chitosan solution was added dropwise to a 0.1% exopolysaccharide solution, and after adjusting
the pH to 4.42, a zeta potential of (–32±5) mV was achieved. For the encapsulation of vitamins C and
E, a 0.3% polymer concentration was used, and the encapsulation efficiency was determined to be
(64.7±0.4) % for vitamin C and (69.8±0.9) % for vitamin E. Cytotoxicity testing on Caco-2 cell lines
demonstrated the biocompatibility of the prepared nanoparticles. Furthermore, the encapsulation
showed the ability to mask the mild cytotoxicity of the P. rhodozyma strain exopolysaccharides
themselves.
The results of this study show that the use of exopolysaccharides as a byproduct of biotechnological
production represents a promising approach for development of carriers for active substances with broad
applications in the food, pharmaceutical, and cosmetic industries.