Preparation and enzymatic activity of penicillin G acylase immobilized on core–shell porous glass beads

In this work, core–shell porous glass beads were used to immobilize the PGA based on the theory that diffusion is the rate-determining step of a reaction with fast kinetics. To improve the loading amount of PGA, chitosan was grafted on the support to increase the interaction between PGA and the support. The effects of flow rate, chitosan concentration and initial concentration of Pen G on immobilized PGA were investigated. The core–shell structure of the support resulted in a higher efficiency of the diffusion of substrate and products, which improved the activity of immobilized PGA. The conversation rate of Pen G (26.9 mmol/L) reached 91.1% when the residential time was about 30 s in the fixed bed reactor. Meanwhile, the conversation rate of 100 mL of Pen G (134.3 mmol/L) reached 89.1% after 8 h in the reactor with recirculation. Moreover, 97.5% activity was retained after seven days of continuous reaction.