Department of Chemical Engineering, Chungbuk National University, Cheongju, Chungbuk 28644, Republic of Korea.
Department of Chemical Engineering, Chungbuk National University, Cheongju, Chungbuk 28644, Republic of Korea.
Int J Biol Macromol. 2020 Jun 15;153:902-911. doi: 10.1016/j.ijbiomac.2020.03.047. Epub 2020 Mar 9.
The present study aims towards the kinetic analysis of bacterial cellulose (BC) production by Gluconobacter xylinus from biodiesel-derived crude glycerol and its application as support for immobilization of lipase. Enhancement in strength of BC membrane and its magnetic functionalization were accomplished by the impregnation of iron oxide nanoparticles into the BC matrix. Fitting of experimental results to various substrate inhibition models revealed a reduction of substrate affinity (K) and reaction rate (V), and increase in substrate inhibition concentration of G. xylinus cells in presence of crude glycerol, in comparison to the pure form of glycerol. Improvement in mechanical properties of pristine BC and magnetic strength of functionalized BC membrane were confirmed by stress-strain curve and vibrating sample magnetometry analysis, respectively. This magnetic BC membrane provided suitable support for the immobilization of Candida rugosa lipase. The immobilized enzymes exhibited better activity at various temperatures, broader pH-flexibility, thermostability (retention of 48% of its activity after 180 min at 50 °C), and reusability (59% of its activity sustained after five consecutive runs). In comparison to free lipase, the immobilized lipase exhibited improved stability and activity, which could be applicable for industrial scale.
本研究旨在分析木葡糖酸醋杆菌从生物柴油衍生的粗甘油中生产细菌纤维素（BC）的动力学，并将其作为固定化脂肪酶的载体。通过将氧化铁纳米颗粒浸渍到 BC 基质中，增强了 BC 膜的强度并实现了其磁性功能化。将实验结果拟合到各种底物抑制模型中表明，与纯甘油相比，在粗甘油存在下，木葡糖酸醋杆菌细胞的底物亲和力（K）和反应速率（V）降低，底物抑制浓度增加。通过应力-应变曲线和振动样品磁强计分析分别证实了原始 BC 的机械性能和功能化 BC 膜的磁性强度的提高。这种磁性 BC 膜为固定化 Candida rugosa 脂肪酶提供了合适的载体。固定化酶在不同温度下表现出更好的活性、更宽的 pH 适应性、热稳定性（在 50°C 下 180 分钟后保留 48%的活性）和可重复使用性（连续五次运行后仍保持 59%的活性）。与游离脂肪酶相比，固定化脂肪酶表现出更好的稳定性和活性，可适用于工业规模。
