The present study reports the partial purification and characterisation of a novel xylanase from Bacillus subtilis subsp. subtilis JJBS250 followed by its applicability in the saccharification of rice straw. Bacterial xylanase was partially purified by gel filtration chromatography using Sephadax G-50 matrix that displayed optimal activity at 60 °C and pH 7.0 with half-life values of 1420 and 718 min at 60 °C and 80 °C, respectively. Bacterial xylanase showed high tolerance to ethanol with K_m and V_max values of 1.62 mg/ml and 23.92 U/ml, respectively, for beechwood xylan. Maximum amount of reducing sugars was obtained from sodium carbonate pretreated rice straw (151.65 mg/g substrate) as compared to untreated biomass (90.49 mg/g substrate) using 20 U/g enzyme dose at 60 °C and pH 7.0 after 48 h. Furthermore, the saccharification of pretreated rice straw was improved by synergistic action of bacterial and fungal xylanases. Analysis of rice straw using scanning electron microscopy (SEM), x-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy clearly showed the morphological changes and delignification in rice straw after pretreatment. Bacterial xylanase exhibiting novel properties including ethanol tolerance and high thermostability is highly suitable for the production of second generation biofuels in simultaneous saccharification and fermentation process using lignocellulosic substrates.

本研究报告了枯草芽孢杆菌亚种中一种新型木聚糖酶的部分纯化和表征。枯草芽孢杆菌JJBS250随后在稻草糖化中的应用。通过使用Sephadax G-50基质的凝胶过滤色谱法部分纯化细菌木聚糖酶，该基质在60°C和pH 7.0下显示最佳活性，在60°C和80°C下的半衰期分别为1420和718 min。细菌木聚糖酶对乙醇具有很高的耐受性，K _m和V _max对于山毛榉木聚糖，其分别的值为1.62mg / ml和23.92U / ml。与碳酸钠预处理的稻草（151.65 mg / g底物）相比，未经还原的生物质（90.49 mg / g底物）在60°C和20 h下使用20 U / g酶剂量处理48小时后可获得最大量的还原糖。此外，通过细菌和真菌木聚糖酶的协同作用改善了预处理稻草的糖化作用。使用扫描电子显微镜（SEM），X射线衍射（XRD）和傅里叶变换红外（FTIR）光谱对稻草进行分析，可以清楚地显示预处理后稻草的形态变化和脱木质素作用。