Bacterial cellulose production from biodiesel-derived crude glycerol, magnetic functionalization, and its application as carrier for lipase immobilization.

The present study aims towards the kinetic analysis of bacterial cellulose (BC) production by Gluconobacter xylinus from biodiesel-derived crude glycerol and its application as support for immobilization of lipase. Enhancement in strength of BC membrane and its magnetic functionalization were accomplished by the impregnation of iron oxide nanoparticles into the BC matrix. Fitting of experimental results to various substrate inhibition models revealed a reduction of substrate affinity (K) and reaction rate (V), and increase in substrate inhibition concentration of G. xylinus cells in presence of crude glycerol, in comparison to the pure form of glycerol. Improvement in mechanical properties of pristine BC and magnetic strength of functionalized BC membrane were confirmed by stress-strain curve and vibrating sample magnetometry analysis, respectively. This magnetic BC membrane provided suitable support for the immobilization of Candida rugosa lipase. The immobilized enzymes exhibited better activity at various temperatures, broader pH-flexibility, thermostability (retention of 48% of its activity after 180 min at 50 °C), and reusability (59% of its activity sustained after five consecutive runs). In comparison to free lipase, the immobilized lipase exhibited improved stability and activity, which could be applicable for industrial scale.