Bacillus licheniformis アルカリ性プロテアーゼのキトサンベース生分解性複合材料への固定化による熱安定性の向上

Given that current enzyme immobilization strategies often face challenges related to enzyme leaching and activity loss, optimizing novel carrier materials is essential for meeting specific industrial requirements, such as high-temperature stability. This study explores the immobilization of alkaline protease from Bacillus licheniformis on biocompatible and biodegradable chitosan/hydroxyapatite (CS/HA) composites using genipin as a natural cross-linker. Moreover, the composites were synthesized via an in-situ hybridization method and characterized through FTIR, XRD, TGA/DTG, SEM, BET, and Fluorescence spectrometry analyses. Results demonstrated that 30 % of HA content provided an optimal microenvironment, achieving high activity recovery (93.7 ± 1.6 %) with an enzyme loading capacity of 86.2 ± 2.2 %. The immobilized enzyme (BAP@CS/HA 30 %) maintained high catalytic efficiency and remarkable thermal stability, retaining over 60 % of its activity after 5 min at 110 °C, compared to the free enzyme, which has lost more than 99 % of its activity. Additionally, it exhibited enhanced reusability, maintaining 43.1 % of its activity after ten cycles. The immobilized protease also showed improved storage stability, retaining 66.8 ± 1.6 % of its activity after 20 days at 4 °C. Notably, this work underscores the potential of CS/HA composites as safe, eco-friendly carriers for protease immobilization.