RESUMEN
ß-Alanine is mainly produced by chemical methods in current industrial processes. Here, panD from Corynebacterium glutamicum encoding L-aspartate-α-decarboxylase (ADC) was cloned and expressed in Escherichia coli BL21(DE3). ADC C.g catalyzes the α-decarboxylation of L-aspartate to ß-alanine. The purified ADC C.g was optimal at 55 °C and pH 6 with excellent stability at 16-37 °C and pH 4-7. A pH-stat directed, fed-batch feeding strategy was developed for enzymatic synthesis of ß-alanine to keep the pH value within 6-7.2 and thus attenuate substrate inhibition. A maximum conversion of 97.2 % was obtained with an initial 5 g L-aspartate/l and another three feedings of 0.5 % (w/v) L-aspartate at 8 h intervals. The final ß-alanine concentration was 12.85 g/l after 36 h. This is the first study concerning the enzymatic production of ß-alanine by using ADC.