Xylitol production from lactose by biotransformation

Xylitol production from lactose was investigated by a three step biotransformations 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 IAM 12953 in the presence of a high concentration ethanol or by cell free sorbitol dehydrogenase. Overall production rate and overall fractional yield of xylitol from lactose were 1.69 mmol L-1 h-1 and 0.141, respectively, when sorbitol dehydrogenase was utilized in the third reaction. The results of xylitol production from lactose were compared with the processes of xylitol production from D-glucose. Keywords: Xylitol, Lactose, Kluyveromyces lactis, Biotransformation Received: 28 November 2009 / Received in revised form: 3 February 2010, Accepted: 13 February 2010, Published online: 11 March 2010