摘要本实验对来源于葎草的一株内生菌株 G8 所产纤维素酶的特性进行研究，以 DNS 方法检测反应前后的葡萄糖含量变化进行酶活力比较。结果表明菌株所产纤维素酶的 不同组分具有不同的适宜反应温度，其中滤纸酶在 70℃时酶活力最好， 羧甲基纤维 素酶和 β-葡萄糖苷酶则在 30℃时具有较好的酶活性，适宜温度下的酶活力分别为 3。562U，11。400U 和 4。923U。底物溶液 pH 对纤维素酶各组分酶活力有明显的影响， 滤纸酶在 pH 为 4。5 时酶活力最大，为 1。943U。而羧甲基纤维素酶和 β-葡萄糖甘酶 的适宜 pH 值都为 3。5，酶活力分别为 0。855U 和 1。270U。羧甲基纤维素酶在不同 pH 条件下处理一段时间后，酶活力稳定性会发生一定变化。在 pH 3。5 和 5。5 的缓冲液 处理酶液时，酶活力保持相对稳定性。pH 4。5 条件下处理 8h 时，羧甲基纤维素酶活 力可达到 12。436U，24h 后，酶活力则下降 64。6%。酶促反应体系中加入 Cu2+、Zn2+和 Fe2+对纤维素酶具有激活作用，可分别使纤维素酶活力增强 27。144%、17。856%和 10%， 而 Mn2+和 Mg2+则对纤维素酶酶活性具有抑制作用，可使纤维素酶活力分别下降 89。29% 和 38。574%。采用 70%饱和度的硫酸铵溶液可将发酵液中蛋白质浓缩 15 倍，但浓缩后 酶液中三种纤维素酶酶活力均远小于浓缩前的粗酶液活力，表明 70%饱和度下的硫酸 铵溶液并不适用于 G8 菌株中纤维素酶的浓缩。82335

毕业论文关键词：内生菌；纤维素酶；羧甲基纤维素酶；金属离子；浓缩

Abstract In this study, the characteristics of the cellulase enzyme of G8 isolated from Humulus Scandens were investigated。 The amount of reducing sugars in the supernatant after enzymatic hydrolysis was measured with the dinitrosalicyclic acid (DNS) method。  Results

showed   that   the   appropriate reaction temperature of   different   components  of

cellulase produced by the strain were different。 The FPAase activity was best in 70℃, and CMCase and β-glycosidase were performed with better enzyme activity in 30℃, the enzyme activities under the appropriate enzymatic reaction temperature were 3。562 U ,

11。400 U and 4。923 U, respectively。 Experimental results indicated that the substrates solution pH had distinct effect on the enzymatic activity of cellulase。 The highest FPAase activity was 1。934U in pH 4。5, and CMCase and β-glycosidase both showed better enzyme activity in pH 3。5( 0。855 U and 0。855 U, respectively )。 The stability of CMCase enzyme activity varied after incubated a period of time in different pH conditions。 The crude enzyme broth was  stable during 24h  when  treated with pH  3。5 and  5。5  buffer   solution。

After incubated with pH 4。5 buffer solution for 8h, the CMCase activity was 12。436 U, and then dropped by 64。6% 24 h later。 Adding Cu2+, Zn2+ and Fe2+ to the enzymatic reaction system would activate the function of cellulase enzyme, which could increase enzyme activity by 27。144%, 17。856% and 10%, respectively。 While the Mn2+ and Mg2+ had inhibitory effect on cellulase enzyme activity, and decreased the cellulase activity by 89。29% and 38。574%, respectively。 The content of protein in crude enzyme broth can concentrate 15 times with 70% saturation of ammonium sulfate solution。 But  the enzymatic activities of three kinds of cellulase in enzyme fluid were much less than that of before concentrated。 It showed that 70% saturation of ammonium sulfate solution did not apply to the concentration of cellulase produced by the G8 strain。

Key Words: Endophytic fungus; Cellulase; CMCase; Metal ions;

目 录

第一章