Modelling of oligodextran production via an immobilized enzyme membrane reactor: Bioreaction-separation coupling mechanism

Use of immobilized enzymatic membrane reactors (EMR) is an effective strategy to enhance oligodextran production efficiency. Nevertheless, the reaction-separation coupling mechanism has not been fully understood. In this study, we developed a model to disentangle the mechanism and interaction behind the reaction and separation phenomena in the immobilized EMR to eventually evaluate process performance for optimal oligodextran production. The simulation results show that in the immobilized EMR applying substrate feeding mode and high operating pressure enhances convective and diffusive flows through membrane, leading to a high transport rate of product. The optimal substrate concentration and enzyme loading amount need to match the selectivity and permeability of the membrane, in order to ensure rapid removal of the target oligodextrans. Therefore, the membranes with high permselectivity are required for obtaining desirable production efficiency and product quality. Although immobilized EMR has higher reaction rate at the beginning because of higher local enzyme concentration in the reaction zone, the EMR with free enzymes could outperform the immobilized EMR by using higher enzyme concentration due to its larger reaction area as the reaction continues. Our study provides deep insights into the reaction-separation coupling mechanism and EMR performance enhancement.