一株阿里地区产纤维素酶菌株的筛选与鉴定

从西藏阿里地区冈仁波齐山脉附近筛选得到了一株产纤维素酶的细菌G1，经形态观察与16S rDNA的序列分析鉴定其为地衣芽孢杆菌（Bacillus licheniformis）。该菌株在30 ℃、pH 7的初始条件下培养76 h后产酶量达到最高，酶活力为0.3 U/mL。酶学性质研究表明，B. licheniformis G1所产纤维素酶的分子质量约为65 ku，其最适反应温度为55 ℃，在30～60 ℃范围内保持50%以上的活力；其最适反应pH为6.0，在pH 5.0～6.0范围内保持95%左右的酶活力；此外，Mn2+对其纤维素酶活力有明显的促进作用，而Cu2+、Mg2+、乙二胺四乙酸（EDTA）对该酶活有较强的抑制作用。

Screening and identification of a cellulase-producing strain from Ngari prefecture

A cellulase-producing bacterium, named as G1, was isolated from the soil of the Kangrinboqe Mountains in Ngari prefecture of Tibet. The strain was identified as Bacillus licheniformis according to the morphological identification and 16S rDNA sequence analysis. The optimized enzyme production could be obtained when the strain was cultivated for 76 h at 30 ℃ with initial pH 7, and the maximum cellulase activity was 0.3 U/ml. The property analysis demonstrated that the molecular weight of the cellulase produced by B. licheniformis G1 was 65 ku, and its optimum reaction condition was temperature 55 ℃, pH 6.0. Moreover, the enzyme maintained more than 50% of its activity in the range of 30-60 ℃, and 95% of CMCase activity was obtained at the pH range of 5.0-6.0. Furthermore, Mn2+ had obvious promoting effect on cellulase activity, while Cu2+, Mg2+, EDTA had strong inhibitory effect on the enzyme activity.