Covalent immobilization of lipase on moderately hydrophilic gigaporous polystyrene microspheres for efficient biosynthesis of benzyl cinnamate

Macroporous polystyrene microspheres have been extensively used as an efficient carrier for lipase immobilization owing to the hydrophobic surface , excellent mechanical strength and chemical stability, easy to recycle and low cost. However, conventional polystyrene microspheres usually have a pore size of less than 100 nm and an extremely hydrophobic surface lacking functional groups, which bring a series of problems such as low enzyme loading, activity recovery, reusability, serious leakage, and high substrate diffusion limitation. In this work, a novel generation of gigaporous polystyrene microspheres with moderately hydrophilic surfaces was specifically designed as an enzymatic carrier. The microspheres were featured with micropores (∼ 9 nm), mesopores (∼ 54 nm), and gigapores (∼ 948 nm), ensuring native enzyme structure preservation and high loading capacity. After epoxy activation, the lipase PS from Burkholderia cepacia (PPL) was site-specifically immobilized onto the microspheres. The resultant immobilized PPL exhibited 95 % activity recovery at a maximum loading of 115.3 mg/g. Also, the immobilized PPL surpassed free PPL in pH and temperature tolerances, temperature and storage stabilities, and achieved a 91.6 % yield in benzyl cinnamate biosynthesis. Besides, excellent reusability of the immobilized PPL was demonstrated with an 80.1 % yield after 10 cycles. Overall, these gigaporous microspheres show great potential for the highly efficient immobilization of lipase and enhanced benzyl cinnamate production.