Bioethanol Production from Xylose-Rich Hydrolysate by Immobilized Recombinant Saccharomyces cerevisiae in Fixed-Bed Reactor

Abstract

Currently, xylose from biomass hemicellulose is still underused, and the fermentation of crude hemicellulose hydrolysates is a challenge due to the presence of inhibitors. Cell immobilization coupled with fixed-bed reactor could create process conditions for high productivity and yields. Thus, in this work, ethanol production in a fixed-bed reactor loaded with Ca-alginate immobilized recombinant Saccharomyces cerevisiae using undetoxified sugarcane bagasse hemicellulose hydrolysate as substrate was studied. Fermentation was carried out in fixed-bed reactor with 100 mL of reaction volume containing 25g of beads (50 g/L of dry cells) at 35°C, pH 5.2. After 4 h, all fermentable sugars were consumed, with low xylitol formation, leading to ethanol yield of 0.39 g/g and productivity of 4.4 g/L.h. This is a promising strategy with potential to implement process operation under repeated batch or continuous mode and therefore increase the chances of achieving economic viability for 2G ethanol production.