Selvarajan E, Mohanasrinivasan V, Subathra Devi C, George Priya Doss C
School of BioSciences and Technology, VIT University, Vellore, Tamil Nadu, India.
Bioprocess Biosyst Eng. 2015 Sep;38(9):1655-69. doi: 10.1007/s00449-015-1407-6. Epub 2015 Apr 30.
β-Galactosidase from Lactobacillus plantarum HF571129 was immobilized on zinc oxide nanoparticles (ZnO NPs) using adsorption and cross-linking technique. Immobilized β-galactosidase showed broad-spectrum pH optima at pH 5-7.5 and temperature 50-60 °C. Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FESEM) showed that β-galactosidase successfully immobilized onto supports. Due to the limited diffusion of high molecular weight substrate, K m of immobilized enzyme slightly increased from 6.64 to 10.22 mM, while V max increased from 147.5 to 192.4 µmol min(-1) mg(-1) as compared to the soluble enzyme. The cross-linked adsorbed enzyme retained 90 % activity after 1-month storage, while the native enzyme showed only 74 % activity under similar incubation conditions. The cross-linked β-galactosidase showed activity until the seventh cycle and maintained 88.02 % activity even after the third cycle. The activation energy of thermal deactivation from immobilized biocatalyst was 24.33 kcal/mol with a half-life of 130.78 min at 35 °C. The rate of lactose hydrolysis for batch and packed bed was found to be 0.023 and 0.04 min(-1).
采用吸附和交联技术将植物乳杆菌HF571129的β-半乳糖苷酶固定在氧化锌纳米颗粒（ZnO NPs）上。固定化β-半乳糖苷酶在pH 5 - 7.5和温度50 - 60°C时表现出广谱的pH最适值。傅里叶变换红外光谱（FTIR）和场发射扫描电子显微镜（FESEM）表明β-半乳糖苷酶成功固定在载体上。由于高分子量底物的扩散受限，固定化酶的K m值从6.64 mM略有增加至10.22 mM，而与可溶性酶相比，V max从147.5 μmol min(-1) mg(-1)增加至192.4 μmol min(-1) mg(-1)。交联吸附的酶在储存1个月后保留了90%的活性，而天然酶在类似的孵育条件下仅表现出74%的活性。交联的β-半乳糖苷酶在第七个循环前仍有活性，甚至在第三个循环后仍保持88.02%的活性。固定化生物催化剂热失活的活化能为24.33 kcal/mol，在35°C下的半衰期为130.78分钟。分批和填充床中乳糖水解的速率分别为0.023和0.04 min(-1)。
