D-GLUCOSE DOES NOT CATABOLITE REPRESS A TRANSKETOLASE-DEFICIENT D-RIBOSE-PRODUCING BACILLUS-SUBTILIS MUTANT STRAIN

When Bacillus subtilis strain ATCC 21951, a transketolase-deficient D- ribose-producing mutant, was grown on D-glucose plus a second substrat e which is metabolized via the oxidative pentose phosphate cycle (D-gl uconic acid, D-xylose, L-arabinose or D-xylitol), D-glucose did not ca tabolite repress metabolism of the second carbon source. The D-ribose yield obtained with the simultaneously converted carbon substrates, si gnificantly exceeded that when only D-glucose was used. In addition, t he concentration of glycolytic by-products and the fermentation time s ignificantly decreased. Based on these findings, a fermentation proces s was developed with B. subtilis strain ATCC 21951 in which D-glucose (100 g L(-1)) and D-gluconic acid (50 g L(-1)) were converted into 45 g L(-1) of D-ribose and 7.5 g L(-1) of acetoin. A second process, base d on D-glucose and D-xylose (1.00 g L(-1) each), yielded 60 g L(-1) of D-ribose and 4 g L(-1) of acetoin plus 2,3-butanediol. Both mixed car bon source fermentations provide excellent alternatives to the less ef ficient D-glucose-based processes used so far.