Biochemical conversion of sugarcane straw hemicellulosic hydrolyzate supplemented with co-substrates for xylitol production

Biotechnological production of xylitol is an attractive route to add value to a sugarcane biorefinery, through utilization of the hemicellulosic fraction of sugarcane straw, whose availability is increasing in Brazil. Herein, supplementation of the sugarcane straw hemicellulosic hydrolyzate (xylose 57 g L-1) with maltose, sucrose, cellobiose or glycerol was proposed, and their effect as co-substrates on xylitol production by Candida guilliermondii FTI 20037 was studied. Sucrose (10 g L-1) and glycerol (0.7 g L-1) supplementation led to significant increase of 8.88% and 6.86% on xylose uptake rate (1.11 g L-1 h(-1) and 1.09 g L-1), respectively, but only with sucrose, significant increments of 12.88% and 8.69% on final xylitol concentration (36.11 g L-1) and volumetric productivity (0.75 g L-1 h(-1)), respectively, were achieved. Based on these results, utilization of complex sources of sucrose, derived from agro-industries, as nutritional supplementation for xylitol production can be proposed as a strategy for improving the yeast performance and reducing the cost of this bioprocess by replacing more expensive nutrients. (C) 2015 Elsevier Ltd. All rights reserved.