Indian Institute of Technology Bombay-Monash Research Academy, Indian Institute of Technology, Bombay, 400076, India; Bio-Processing laboratory, Centre for Technology Alternatives for Rural Areas, Indian Institute of Technology, Bombay, 400076, India; Department of Gastroenterology, Central Clinical School, Monash University, Melbourne, Victoria, 3004, Australia.
Indian Institute of Technology Bombay-Monash Research Academy, Indian Institute of Technology, Bombay, 400076, India; Bio-Processing laboratory, Centre for Technology Alternatives for Rural Areas, Indian Institute of Technology, Bombay, 400076, India.
Enzyme Microb Technol. 2019 Nov;130:109368. doi: 10.1016/j.enzmictec.2019.109368. Epub 2019 Jun 25.
In this work, the effect of particle size on alkali pretreatment of the almond shell was evaluated for recovery of hemicellulose. Further, endoxylanase from Thermomyces lanuginosus was immobilized on Fe-based magnetic nanoparticles to enable reuse of enzyme. Reduction in particle size significantly influences the recovery of hemicellulose as particle size below 120 μm enable recovery of 97% available hemicellulose in 1 h at 121 °C with 2 M alkali. The enzyme could retain 93.3% of enzymatic activity upon immobilization onto magnetic support using glutaraldehyde (25 mM) and was at par with the free enzyme in terms of pH and temperature profile. The measurement of reaction kinetics (Km and Vmax) indicates similar values for free and immobilized enzyme. The structural and morphological analysis indicates presence near spherical magnetic core and successful cross-linking of the enzyme without alteration of the magnetic core. The immobilized enzyme was able to hydrolyze hemicellulose to produce XOS, the yield equivalent to 67.4% of that obtained using free enzyme at 50 °C. The comparison of XOS production ability at 50 and 60 °C, suggests that the immobilized enzyme retains activity as similar yield was obtained at both temperatures, whereas, the yield for free enzyme decreases significantly. The XOS yield on recycling of immobilized enzyme for three successive cycles was found to reduce to 41% of the initial cycle. However, in all cycles of enzymatic hydrolysis, the percentage of xylobiose was found to be above 90%.
在这项工作中，评估了杏仁壳的粒径对碱预处理的影响，以回收半纤维素。此外，来自嗜热丝孢菌的内切木聚糖酶被固定在 Fe 基磁性纳米颗粒上，以实现酶的重复使用。粒径的减小显著影响半纤维素的回收，因为粒径小于 120μm 时，在 121℃下用 2M 碱处理 1h 可回收 97%的有效半纤维素。用戊二醛（25mM）将酶固定在磁性载体上后，酶可保留 93.3%的酶活性，在 pH 和温度谱方面与游离酶相当。反应动力学（Km 和 Vmax）的测量表明，游离酶和固定化酶具有相似的值。结构和形态分析表明存在近球形的磁性核，并且酶的交联成功，而磁性核没有改变。固定化酶能够水解半纤维素生成 XOS，其产率与在 50℃下使用游离酶时相当，达到 67.4%。在 50 和 60℃下比较 XOS 生产能力表明，固定化酶保留活性，因为在这两种温度下都获得了相似的产率，而游离酶的产率则显著下降。固定化酶在连续三个循环中的重复使用中，XOS 的产率降至初始循环的 41%。然而，在所有酶水解循环中，木二糖的百分比都高于 90%。
