Purification and characterization of an organic-solvent-tolerant cellulase from a halotolerant isolate, Bacillus sp L1
Purification and characterization of an organic-solvent-tolerant cellulase from a halotolerant isolate, Bacillus sp L1
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DOI：
10.1007/s10295-012-1120-2
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发表时间：
2012-08-01
影响因子：
3.4
通讯作者：
Yu, Hui-Ying
中科院分区：
文献类型：
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作者：
Li, Xin;Yu, Hui-Ying
从运城地区分离到一株产纤维素酶的耐盐芽孢杆菌L1。该酶的产生从细菌生长的指数中期开始，并在稳定期后达到最高水平。纤维素酶纯化至均一，分子量为45 kDa。底物专一性试验表明，该酶是一种可溶性纤维素内切酶。发现最佳酶活性是在60 A ° C、pH 8.0和7.5%NaCl下。此外，它在宽的温度（30-80 A ° C）、pH（7.0-9.0）和NaCl浓度（2.5- 15%）范围内具有高活性和稳定性，因此显示出其优异的热稳定性、碱稳定性和耐盐性。乙二胺四乙酸对纤维素酶活性有明显的抑制作用，表明该酶为金属酶。苯甲基磺酰氟和氧化苯胂的显着抑制作用表明，丝氨酸和半胱氨酸残基是必不可少的酶催化。此外，纤维素酶在表面活性剂的存在下是高度活性的，并且它在水不溶性有机溶剂的存在下显示出高稳定性，log P（ow）至少为0.88。研究结果表明，L1菌株的纤维素酶具有良好的工业应用前景。
A halotolerant isolate Bacillus sp. L1 producing extracellular cellulase was isolated from Yuncheng, China. Production of the enzyme started from mid-exponential phase of bacterial growth and reached a maximum level during the post-stationary phase. The cellulase was purified to homogeneity with molecular mass of 45 kDa. Substrate specificity test indicated that it was an endoglucanase for soluble cellulose. Optimal enzyme activity was found to be at 60 A degrees C, pH 8.0, and 7.5 % NaCl. Furthermore, it was highly active and stable over broad ranges of temperature (30-80 A degrees C), pH (7.0-9.0), and NaCl concentration (2.5-15 %), thus showing its excellent thermostable, alkali-stable, and halotolerant nature. The cellulase activity was greatly inhibited by ethylenediaminetetraacetic acid, indicating that it was a metalloenzyme. Significant inhibition by phenylmethylsulfonyl fluoride and phenylarsine oxide revealed that serine and cysteine residues were essential for the enzyme catalysis. Moreover, the cellulase was highly active in the presence of surfactants, and it showed high stability in the presence of water-insoluble organic solvents with log P (ow)at least 0.88. Results from this study indicate that the purified cellulase from isolate L1 may have considerable potential for industrial application owing to its useful properties.