XYLOSE REDUCTASE AND XYLITOL DEHYDROGENASE-ACTIVITIES OF D-XYLOSE-XYLITOL-FERMENTING CANDIDA-GUILLIERMONDII

The effect of the inoculum age and initial xylose concentration on the activities of xylose reductase (XR) and xylitol dehydrogenase (XD) of Candida guilliermondii FTI 20037 were investigated. Under the experim ental conditions used, the XR and XD activities were, respectively, NA DPH and NAD or NADP dependent. The NADP/NADPH ratio for XR was not sub stantially influenced by the age of inoculum or the initial xylose con centration. The K-m of XR (0.18 M) was about 4-folds smaller than the K-m of XD NAD-dependent. A renewable xylose-xylitol conversion was obt ained with 40 h aged inoculum of Candida guilliermondii FTI 20037 grow n in a medium containing an initial xylose concentration of 120 g/l.