Niu Qiuhong, Zhang Guo, Zhang Lin, Ma Yali, Shi Qian, Fu Weiwei
School of Life Science and Technology, Nanyang Normal University, Nanyang, 473000, PR China.
School of Life Science and Technology, Nanyang Normal University, Nanyang, 473000, PR China.
J Biosci Bioeng. 2016 May;121(5):503-8. doi: 10.1016/j.jbiosc.2015.10.007. Epub 2015 Nov 14.
An extracellular 1,3-1,4-β-glucanase-producing strain S2 was isolated from booklice and identified as Bacillus methylotrophicus. Furthermore, a homogeneous extracellular 1,3-1,4-β-glucanase GCS2 was purified by ammonium sulfate precipitation and cation-exchange chromatography. The gene for the 1,3-1,4-β-glucanase was cloned, and the nucleotide sequence was determined. Characterization of the purified enzyme revealed the molecular mass of 26 kDa and the optimum activity at pH 7.5, 55°C. The purified enzyme can highly hydrolyze carboxymethylcellulose including oat gum, barley β-glucan, CMC and lichenan, while low activity on avicel, cellobiose, filter paper, p-nitrophenyl β-d-cellobioside, and p-nitrophenyl β-d-glucoside, but no activity against microcrystalline cellulose or salicin. The enzyme was stable at wide range of pHs 5-10 and still maintained above 60% activity at 70°C. The enzyme activity was stimulated by Trixon X-100. The property of the enzyme GCS2 makes this enzyme a broad prospect in brewing and commercial detergent industry. To our knowledge, this is the first report of a 1,3-1,4-β-glucanase from microbes associated with booklice.
从书虱中分离出一株产胞外1,3 - 1,4-β-葡聚糖酶的菌株S2，并鉴定为甲基营养芽孢杆菌。此外，通过硫酸铵沉淀和阳离子交换色谱法纯化得到了一种均一的胞外1,3 - 1,4-β-葡聚糖酶GCS2。克隆了1,3 - 1,4-β-葡聚糖酶的基因，并测定了其核苷酸序列。对纯化酶的特性分析表明，其分子量为26 kDa，在pH 7.5、55°C时具有最佳活性。该纯化酶能高效水解包括燕麦胶、大麦β-葡聚糖、羧甲基纤维素和地衣多糖在内的羧甲基纤维素，而对微晶纤维素、纤维二糖、滤纸、对硝基苯基β-D-纤维二糖苷和对硝基苯基β-D-葡萄糖苷的活性较低，但对微晶纤维素或水杨苷无活性。该酶在pH 5 - 10的宽范围内稳定，在70°C时仍保持60%以上的活性。吐温X - 100能刺激该酶的活性。酶GCS2的特性使其在酿造和商业洗涤剂行业具有广阔的应用前景。据我们所知，这是首次报道从与书虱相关的微生物中获得1,3 - 1,4-β-葡聚糖酶。
