Sorbitol and gluconic acid production using permeabilized Zymomonas mobilis cells confined by hollow-fiber membranes

Immobilization of Zymomonas mobilis by different methods was investigated. Experiments were performed in order to choose the most appropriate support for the immobilization of the cells. The most advantageous option was to us e permeabilized cells in the bore of microporous hollow fibers. Whereas the reaction rate was about 33 g of gluconate /(g of protein.h) using hollow f ibers, which is comparable to that observed by using free cells, the calciu m alginate immobilized cells presented a reaction rate of 4 g of gluconate/ (g of protein.h). These results can be explained by the mass transfer resis tance effect, which, indeed, was much lower in the case of hollow-fiber mem branes than in the alginate gel beads. A loss of enzymatic activity during the reaction was observed in all experiments, which was attributed to the l actone produced as an intermediate of the reaction.