Yeast Cells Immobilized in Ionic Crosslinked Hydrogel Particles Based on Gellan and Gellan/Carboxymethyl Cellulose-Comparative Study

The present work deals with the study of obtaining the spherical particles containing brewer yeast cells immobilized in a hydrogel matrix based on gellan and gellan/carboxymethyl cellulose (sodium salt). The influence of some factors of the process for obtaining the particles, by the ionic gelation with magnesium acetate used as crosslinking agent, by an extrusion process through capillary, on the particles properties such as structural stability, on morphological characteristics and on behavior in aqueous and alcoholic medium of the particles with or without yeast cells immobilized was studied. The particles were obtained from the mixtures of the two polysaccharides and theirs properties were compared to those based only on gellan. One can observe a certain influence of the CMCNa amount on the above mentioned properties essentially determined by their higher crosslinking density of the polymers mixture compared to those prepared only with gellan. Biocatalytic properties of the particles with yeast cells immobilized depends also on the crosslinking density; the bioreactors with a higher concentration of CMCNa present a slightly lower biocatalytic activity. The particles with immobilized yeast cells can be used for a higher number of hydrolitic cycles; the number of cycles decreases when the CMCNa content increases in the particles composition due to the higher crosslinking degree leading to the inhibition of the yeast cells proliferation.