Xylitol production from lactose by biotransformation

Xylitol production from lactose was investigated by a three stepbiotransformations series that were: (1) breakdown of lactose to Darabitol by Kluyveromyces lactis NBRC 1903, (2) oxidation of Darabitol to D-xylulose by Gluconobacter oxydans NBRC 3172, and(3) reduction of D-xylulose to xylitol by Candida shehatae IAM12953 in the presence of a high concentration ethanol or by cell freesorbitol dehydrogenase. Overall production rate and overallfractional yield of xylitol from lactose were 1.69 mmol L-1 h-1 and0.141, respectively, when sorbitol dehydrogenase was utilized in thethird reaction. The results of xylitol production from lactose werecompared with the processes of xylitol production from D-glucose.