SIMULTANEOUS ISOMERIZATION AND FERMENTATION OF XYLOSE AS A STRATEGY FOR HEMICELLULOSE VALORIZATION: INTRAPARTICLE DIFFUSIVE EFFECT OF IMMOBILIZED XYLOSE ISOMERASE
Keywords:
2G Ethanol, Biorefinery, Simultaneous Isomerization and Fermentation, Heterogeneous Catalysts, Enzyme ImmobilizationAbstract
Considering the context of biorefineries, the hemicellulosic fraction of biomass is still underutilized. However, for the production of 2G ethanol from biomass to be viable, it is necessary to establish a way to utilize this fraction. Saccharomyces cerevisiae yeast does not consume xylose, but it does consume its isomer, xylulose. In this context, the use of xylose from hemicellulose can be made feasible through Simultaneous Isomerization and Fermentation (SIF), using the enzyme xylose isomerase. To enable continuous or repeated batches operation, the enzyme can be co-immobilized with the yeast, providing a protective microenvironment against process conditions. However, since diffusive effects from the presence of immobilization supports can render the process unfeasible, characterization of this property is necessary. Thus, the present work evaluated the intraparticle diffusive effects of the xylose isomerase derivative immobilized on chitosan at different diameters, aiming to prove its viability in the SIF process. The IXI-Ch derivative obtained by immobilization in chitosan gel was found to be free of intraparticle effects, presenting kinetic parameters similar to those of the soluble enzyme. The use of this derivative co-immobilized with yeast in calcium alginate beads for the continuous production of 2G ethanol proved to be viable, since under the process conditions it showed an internal effectiveness of 94.5%.
