Research of the immobilization of microbial cells in sodium alginate for D-Psicose conversion

D-Psicose 3-epimerase( DPEase) is an enzyme that catalyzes the reversible isomerization between D-fructose and D-psicose.In this study,the calcium alginate gels was used as carrier to immobilize the microbial cells with DPEase.The enzymatic properties of the immobilized and free DPEase were studied to get the optimal parameters. The results showed that the optimum operation conditions were: 3.0% sodium alginate,60 g/L of embedded cell,2% Ca Cl2,solidifying time 4h,0.01% flutaraldehyde,crosslinking time 4h.Under the optimum condition,the recovery rate reached 76%.After eight times repeated operations,the recovery rate reached more than 61%,showing good operational stability. Compared with the free microbial cells with DPEase,the optimum temperature of immobilized DPEase raises 5 degrees,the p H value wasn't changed.Besides,the p H and thermal stabilities of immobilized DPEase were better than the free microbial cells.