| 摘要: |
| 【目的】对本课题组分离的一株纤维素降解菌进行鉴定，优化其产酶条件并检测其对饲料粗纤维的降解效果,以期为该菌在饲料粗纤维降解中的应用提供理论依据。【方法】通过菌株形态特征和16S rDNA 序列分析鉴定了实验室分离保存的一株纤维降解菌；研究该菌所产纤维素酶的部分酶学性质和酶谱,并优化其产纤维素酶的条件；利用体外发酵和尼龙袋法测定菌株N3所产粗酶液对3种饲料（麸皮、麦草、燕麦）粗纤维的降解率；利用RB亮蓝脱色试验检测该菌的木质素降解能力。【结果】经鉴定，该菌株为枯草芽孢杆菌，命名为Bacillus subtilis N3；N3菌株不产生漆酶，主要向胞外分泌分子质量70 ku以上的纤维素酶组分；N3菌株所产纤维素酶的最适反应温度和pH分别为60 ℃和5.5；N3菌株以体积比1∶50接种至最适发酵培养基（碳源为麸皮、氮源为蛋白胨，初始pH为5），37 ℃培养24 h时，所产纤维素酶活性最高，可达3.50 U/mL；菌株N3所产粗酶液对麸皮的粗纤维降解率最高，对麦草秸秆的粗纤维降解率最低。【结论】分离到的纤维降解菌Bacillus subtilis N3主要分泌分子质量70 ku 以上、耐热的纤维素酶，对饲料粗纤维具有较强的降解能力。 |
| 关键词: 枯草芽孢杆菌 纤维素酶 酶学性质 纤维素降解 酶谱分析 |
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| 基金项目:国家自然科学基金项目(31072060；31372343)；国家绒毛用羊产业技术体系项目(CARS-40-13)；国家公益性行业（农业）专项(20130305905) |
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| Identification of a cellulose-decomposing strain and its application for degrading different cellulosic materials |
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WANG Yaoyue,CAO Pinghua,CHEN Yulin,et al
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| Abstract: |
| 【Objective】A cellulose-decomposing strain was identified,its optimal cultivating conditions for cellulase production were determined and the crude fiber utilization rate was tested to provide basis for its application.【Method】A cellulosic decomposing bacterium was identified by morphology and 16S rDNA gene sequences.Then,the enzymatic properties of Bacillus subtilis N3 were studied and cultivation conditions for cellulase production were optimized.Degradation of three feedstuffs (wheat bran,wheat straw,oat straw) by cellulose from the strain N3 was conducted.The lignin decomposing capacity of the strain was also tested using brilliant blue RB method.【Result】The strain was identified and named Bacillus subtilis N3.The optimal temperature and pH for the CMCase activity of the crude enzyme were 60 ℃ and 5.5,respectively.Zymogram analysis showed that one CMCase with molecular weight of 70 ku was primary secreted by Bacillus subtilis N3.The optimal conditions of producing cellulase were 24 h,37 ℃,wheat bran,peptone,initial pH 5.0 and 1∶50 for initial inoculums.The average activity of CMCase activity reached 3.5 U/mL.The highest degradation rate of crude fiber was observed for wheat bran,while the lowest degradation rate was for wheat straw.In addition,Bacillus subtilis N3 failed to produce laccase and could not degrade lignin.【Conclusion】Cellulose-decomposing strain Bacillus subtilis N3 mainly secreted a cellulase with molecular weight of 70 ku and its degradability of crude fiber was strong. |
| Key words: Bacillus subtilis cellulase enzymatic property cellulose degradation zymographic analysis |
