Optimization of immobilization for selective oxidation of benzyl alcohol by Gluconobacter oxydans using response surface methodology

This study used the Box–Behnken design and response surface methodology to optimize immobilization of Gluconobacter oxydans in Ca-alginate gel for the production of benzaldehyde in a biphasic system. Immobilization parameters, such as Na-alginate concentration, cell load, and bead diameter, were optimized. The mathematical model developed was validated and proven to be statistically adequate and accurate in predicting the response. For both activity and stability responses, the best results were achieved at alginate concentration of 2.55% (w/v), cell load of 49.26 mg/ml, and 2.2 mm bead diameter. Under these conditions, retention activity of 87.6% could be attained for the immobilized cell. In addition, the oxidative activity of immobilized cells was retained at 53.2% compared with that of free cells after 10 repeated batch reactions, while only 15.7% of activity remained in free cells.