Biofuels Institute, School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang 212013, Jiangsu, China.
Biofuels Institute, School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang 212013, Jiangsu, China.
Int J Biol Macromol. 2018 Apr 1;109:872-879. doi: 10.1016/j.ijbiomac.2017.11.072. Epub 2017 Nov 11.
A β-glucosidase gene from Bacillus cellulosilyticus was expressed in Escherichia coli BL21 and characterized. The recombinant enzyme (BcBgl1A) showed the optimal activity at 40°C, and the half-life of BcBgl1A activity at 40°C was 24h. BcBgl1A was sensitive to heat and exhibited obvious cold-adapted activity, retained 27.2% and 46.5% of the optimal activity at 4 and 20°C, respectively. The best activity was observed at pH 7.0 and stable over the range of pH 6.0-8.0. The activity was significantly enhanced by Fe, Fe and Mn, also showed a high level of NaCl tolerance. BcBgl1A exhibited high activity using both pNPG and cellobiose as substrates, the V for pNPG and cellobiose was 66.2 and 151.5U/mg of protein, respectively, and its K values were 2.97 and 10.4mM, respectively. Catalysis efficiency (K/K) of 45.8s (cellobiose) and 70.3s (pNPG). It displayed high tolerance to glucose and ethanol, the K and IC50 value was 200mM and 15% (v/v), respectively. Additionally, the BcBgl1A was found to be highly efficient for conversion of cellobiose (100g/L) to ethanol by simultaneous saccharification and fermentation process, achieved an ethanol content of 47.2g/l corresponding to 87.9% of the theoretical ethanol yield. The results suggest that BcBgl1A has a potential for biotechnological applications in the bioconversion of lignocellulosic materials.
从纤维素分解芽孢杆菌中表达了一种β-葡萄糖苷酶基因，并对其进行了表征。重组酶（BcBgl1A）在 40°C 下表现出最佳活性，在 40°C 下的半衰期为 24 小时。BcBgl1A 对热敏感，表现出明显的冷适应活性，分别在 4°C 和 20°C 下保留了最佳活性的 27.2%和 46.5%。在 pH7.0 下观察到最佳活性，在 pH6.0-8.0 范围内稳定。Fe、Fe 和 Mn 显著增强了酶的活性，也表现出较高的耐盐性。BcBgl1A 以 pNPG 和纤维二糖为底物均表现出较高的活性，pNPG 和纤维二糖的 V 分别为 66.2 和 151.5U/mg 蛋白，其 K 值分别为 2.97 和 10.4mM。对纤维二糖（45.8s）和 pNPG（70.3s）的催化效率（K/K）。它对葡萄糖和乙醇具有较高的耐受性，K 和 IC50 值分别为 200mM 和 15%（v/v）。此外，BcBgl1A 在纤维二糖（100g/L）的同步糖化发酵过程中对乙醇的转化具有很高的效率，达到了 47.2g/l 的乙醇含量，对应于理论乙醇产率的 87.9%。结果表明，BcBgl1A 在木质纤维素材料的生物转化中具有潜在的生物技术应用价值。
