Bioinspired Production of Antibacterial Sucrose Isomerase-Sponge for the Synthesis of Isomaltulose

Isomaltulose is a new functional sweetener that possesses biological characteristics and can be obtained by enzymatic synthesis using sucrose as substrate. In this study, the sucrose isomerase (SIase) was successfully immobilized on the sponge synthesized with ϵ-poly-l-lysine and gelatin. The inhibition zones proved that the sponge possessed a significant bacteriostatic function, which can effectively prevent the collapse of the scaffolds of the immobilized enzymes. The immobilized SIase activity reached up to 71.58 U g⁻¹ (the SIase loading was about 153.43 mg g⁻¹), and the activity recovery was approximately 84.50%. After immobilization, the optimum pH of SIase decreased from 6.0 to 5.5 and the optimum temperature increased from 30 °C to 40 °C. The affinity of SIase to substrate was basically unchanged. Immobilized SIase still exhibited more than 90% sucrose conversion after 13 consecutive cycles, which indicated that it had a good operational stability. Furthermore, the immobilized SIase has the potential for isomaltulose production, with 200 g L⁻¹ sucrose solution as its substrate in the food industry. Isomaltulose was isolated in 83.58% yield and high purity (97.3%). (Figure presented.).