Use of immobilized Candida cells on xylitol production from sugarcane bagasse

In this study we used the yeast Candida guilliermondii FTI 20037 immobilize d by entrapment in Ca-alginate beads (2.5-3 mm diameter) for xylitol produc tion from concentrated sugarcane bagasse hemicellulosic hydrolysate in a re peated batch system. The fermentation runs were carried out in 125- and 250 -ml Erlenmeyer flasks placed in an orbital shaker at 30 degrees C and 200 r pm during 72 h, keeping constant the proportion between work volume and fla sk total volume. According to the results, cell viability was substantially high (98%) in all fermentative cycles. The values of parameters xylitol yi eld and volumetric productivity increased significantly with the reutilizat ion of the immobilized biocatalysts. The highest values of xylitol final co ncentration (11.05 g/l), yield factor (0.47 g/g) and volumetric productivit y (0.22 g/lh) were obtained in 250-ml Erlenmeyer flasks containing 80 mi of medium plus 20 mi of immobilized biocatalysts. The support used in this st udy (Ca-alginate) presented stability in the experimental conditions used. The results show that the use of immobilized cells is a promising approach for increasing the xylitol production rates.