A novel halotolerant xylanase from marine isolate Bacillus subtilis cho40: gene cloning and sequencing
A novel halotolerant xylanase from marine isolate Bacillus subtilis cho40: gene cloning and sequencing
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DOI：
10.1016/j.nbt.2011.08.001
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发表时间：
2011-10-01
影响因子：
5.4
通讯作者：
Deobagkar, Deepti
中科院分区：
文献类型：
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作者：
Khandeparker, Rakhee;Verma, Preeti;Deobagkar, Deepti
尽管已经研究了几种木聚糖酶，但仅报道了少数来自海洋微生物的木聚糖酶。我们在此报告了一种新型耐盐木聚糖酶，该酶来自从印度果阿曼多维河口乔劳岛分离的海洋细菌枯草芽孢杆菌 cho40。胞外木聚糖酶是利用麦麸等农业残留物作为碳源，通过固态发酵（SSF）生产的。据报道，木聚糖酶的最适pH和温度分别为6.0和60℃。 Xyn40 具有高度耐盐性，在 0.5 M NaCl 下表现出最高活性。当与 0.5 M NaCl 预孵育 4 小时时，木聚糖酶活性被大大诱导 (140%)。克隆了来自海洋细菌枯草芽孢杆菌 cho40 的木聚糖酶基因 xyn40，并在大肠杆菌中表达。木聚糖酶基因长645 bp，具有215个氨基酸的ORF蛋白，分子量为22.9 kDa。它具有木聚糖酶的所有特征，并且与枯草芽孢杆菌报道的木聚糖酶具有同源性。它与早期报道的木聚糖酶序列的不同之处在于，与苏氨酸相比，它存在更多的丝氨酸残基，并且极性（亲水性）氨基酸的丰度（61%）高于非极性氨基酸（39%）。本研究报道的新型木聚糖酶是一种来自海洋分离物的耐盐酶，在海洋海藻生产生物乙醇中可以发挥非常重要的作用。
Although several xylanases have been studied, only few xylanases from marine micro-organisms have been reported. We report here a novel halotolerant xylanase from marine bacterium Bacillus subtilis cho40 isolated from Chorao island of mandovi estuary Goa, India. Extracellular xylanase was produced by using agricultural residue such as wheat bran as carbon source under solid-state fermentation (SSF). The optimal pH and temperature of xylanase were reported to be 6.0 and 60 degrees C, respectively. Xyn40 was highly salt-tolerant, and showed highest activity at 0.5 M NaCl. Xylanase activity was greatly induced (140%) when pre-incubated with 0.5 M NaCl for 4 h. The xylanase gene, xyn40, from marine bacterium B. subtilis cho40 was cloned, and expressed in Escherichia coli. The xylanase gene was 645 bp long and had a 215 amino acid ORF protein with a molecular mass of 22.9 kDa. It had all features of xylanase enzyme and showed homology to xylanases reported from B. subtilis. It differs from the earlier reported xylanase sequences by the presence of more serine residues compared to threonine and also by the presence of polar (hydrophilic) amino acids in higher abundance (61%) than non-polar amino acids (39%). The novel xylanase, reported in this study is a halotolerant enzyme from marine isolate and can play a very important role in bioethanol production from marine seaweeds.