Characterization of a bifunctional xylanase/endoglucanase from yak rumen microorganisms
Characterization of a bifunctional xylanase/endoglucanase from yak rumen microorganisms
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DOI：
10.1007/s00253-011-3182-x
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发表时间：
2011-06-01
影响因子：
5
通讯作者：
Lu, Hong
中科院分区：
文献类型：
--
作者：
Chang, Lei;Ding, Mozhu;Lu, Hong
从牦牛瘤胃微生物宏基因组文库中克隆了一个编码双功能木聚糖酶/内切葡聚糖酶的新基因RuCelA。RuCelA对木聚糖和羧甲基纤维素（CMC）具有抑制活性，表明其具有双功能木聚糖酶/内切葡聚糖酶活性。木聚糖酶和内切葡聚糖酶活性的最佳条件分别为65℃，pH 7.0和50℃，pH 5.0。此外，Co+和Co2+的存在可以大大提高RuCelA的内切葡聚糖酶活性，抑制其木聚糖酶活性。进一步的底物偏好检测表明，对大麦葡聚糖和地衣素的活性高于对木聚糖和CMC的活性。RuCelA以木聚糖和大麦葡聚糖为底物，与-1,4-木糖苷酶和-1,4-葡萄糖苷酶表现出明显的协同作用。木质纤维素生成可溶性低聚糖是生物乙醇生产的关键步骤，值得注意的是，在预处理稻草的连续糖化过程中，RuCelA可以生成低聚木糖和纤维素低聚糖，这些低聚木糖和纤维素低聚糖可以进一步降解为可发酵糖。因此，双功能RuCelA使其成为工业应用的理想候选者。
A new gene, RuCelA, encoding a bifunctional xylanase/endoglucanase, was cloned from a metagenomic library of yak rumen microorganisms. RuCelA showed activity against xylan and carboxymethylcellulose (CMC), suggesting bifunctional xylanase/endoglucanase activity. The optimal conditions for xylanase and endoglucanase activities were 65A degrees C, pH 7.0 and 50A degrees C, pH 5.0, respectively. In addition, the presence of Co+ and Co2+ can greatly improve RuCelA's endoglucanase activity, while inhibits its xylanase activity. Further examination of substrate preference showed a higher activity against barley glucan and lichenin than against xylan and CMC. Using xylan and barley glucan as substrates, RuCelA displayed obvious synergistic effects with beta-1,4-xylosidase and beta-1,4-glucosidase. Generation of soluble oligosaccharides from lignocellulose is the key step in bioethanol production, and it is greatly notable that RuCelA can produce xylo-oligosaccharides and cello-oligosaccharides in the continuous saccharification of pretreated rice straw, which can be further degraded into fermentable sugars. Therefore, the bifunctional RuCelA distinguishes itself as an ideal candidate for industrial applications.