| 초록 |
D-Ribose is a five-carbon sugar to be used in commercial syntheses of riboflavin, antiviral agents and flavor enhancers. Bacillus subtilis SPK1, a transketolase-deficient mutant, has an ability to produce D-ribose from D-xylose through the non-oxidative pentose phosphate pathway. Fed-batch fermentations with a mixture of xylose and glucose were performed to optimize the feeding strategies, start point of fed-batch mode and composition of feeding solution. Feeding after 20hrs of the batch-type culture gave the best result of 18.2 of optical density, 43.5g/L of D-ribose and 0.9g/L-hr of D-ribose productivity. To determine the optimal composition of xylose and glucose in the feeding solution, fed-batch cultivations were carried out with various feeding solutions at the ratio of xylose to glucose, 4 to 1, 4 to 2 and 4 to 3. Addition of 200g/L xylose and 50g/L glucose maintained a glucose level below 2g/L in culture broth and resulted in D-ribose concentration of 46.6 g/L and productivity of 1.4g/L-hr, which is a 2.3- and 1.5-fold increase compared with the simple batch fermentation, respectively. |
