PRODUCTION OF XYLITOL FROM D-XYLOSE BY CANDIDA-TROPICALIS - THE EFFECT OF D-GLUCOSE FEEDING

D-Glucose fed-batch cultivation was studied for effective production o f xylitol from D-xylose by Candida tropicalis. When D-xylose was used as a single carbon source, the yeast consumed D-xylose for production of xylitol as well as for growth and cell maintenance resulting in dec reased xylitol yield. To improve the xylitol yield, it is necessary to increase the cell mass using another carbon source. We selected D-glu cose for the purpose and as a result, a 1.1-1.2 times higher yield and a 1.2-1.3 times higher production rate were obtained by supplementati on of D-glucose using column reactors (200 ml scale). In a bench-scale fermenter (3 l scale) experiment, xylitol was produced at up to 104.5 g/l at 32 h cultivation and a yield of 0.82 (g/g D-xylose consumed) a nd production rate of 3.26 g/l . h were obtained. These values are 1.3 times and 1.2 times higher for yield and production rate, respectivel y, than those obtained under optimum cultivation conditions for produc tion rate previously reported.