Coupling of an electrodialysis unit to a hollow fiber bioreactor for separation of gluconic acid from sorbitol produced by Zymomonas mobilis permeabilized cells

The objective of this study was to evaluate the coupling of an electrodialysis unit to a reactor in which gluconic acid and sorbitol were produced by permeabilized and immobilized Zymomonas mobilis cells. The experimental results have shown that electrodialysis unit coupled to the bioreactor allowed an efficient removal of gluconic acid from the reaction medium, as well as an improvement in the stability of the enzyme. It was not observed any reduction in the reaction rate, even after 60 h of operation. On the other hand, when NaOH was applied to neutralize the gluconic acid produced, it was verified a reduction of 80% in the reaction rate in the same period. These results lead to the hypothesis that the enzyme stability is associated to gluconate accumulation in the reaction medium.