Abstract
Effect of arabinose on xylitol production from xylose by Candida parapsilosis KFCC 10875 was investigated at the different concentrations of arabinose. When the arabinose was added in xylose medium, the cell growth increased and the final cell concentration was maximum at 10 g/l arabinose. The consumption rate of arabinose was greatly lower than those of xylose and arabinose. Above 10 g/l arabinose, it was not completely consumed and then remained in the medium during xylitol fermentation. Estimated cell mass obtained from arabinose increased with increasing consumed arabinose. As arabinose concentration was increased, xylitol production decreased but ethanol production increased. The inhibitory effect of ethanol, a major by-product, on xylitol production was also studied. As the ethanol concentration added increased, xylitol production decreased. When cells were inoculated in a xylose medium after removing ethanol, xylitol production was not inhibited. This results suggested that the inhibition of xylitol production resulted from ethanol which was formed by adding arabinose. It was also interesting that total products(xylitol and ethanol) yield was constant regardless of the arabinose concentration. This result suggested that the total amount of products such as xylitol and ethanol from xylose was constant regardless of the arabinose concentration and arabinose shifted the carbon flow from xylitol to ethanol.
