Xylitol production in a bubble column bioreactor: Influence of the aeration rate and immobilized system concentration

This work evaluated the xylitol production from sugarcane bagasse hemicellulosic hydrolysate in a bubble column bioreactor using cells of the yeast Candida guilliermondii immobilized in calcium-alginate. The fermentation runs were performed according to a 22 full factorial design with three replicates at the center point in order to determine the effect of the variables: aeration rate (0.66–1.33 vvm) and immobilized system concentration (20–40% v/v), on the efficiency of xylose-to-xylitol conversion and on the xylitol volumetric productivity. The results indicated a significant influence of both variables on xylitol production. The highest conversion efficiency (41%) was attained using 1.33 vvm aeration rate and 40% immobilized system. Under these conditions, the volumetric productivity was 0.21 g l−1 h−1.