一株产果胶酶芦苇内生真菌的分离、鉴定及酶学性质研究

以果胶为唯一碳源，采用十六烷基三甲基溴化胺（CTAB）沉淀法从芦苇中筛选产果胶酶菌株，根据形态观察和内转录间隔区（ITS）序列分析对其进行鉴定，并对其所产果胶酶的酶学性质进行研究。结果表明，筛选出一株高产果胶酶的内生真菌，编号为z4，菌株z4被鉴定为红绶曲霉（Aspergillus nomius）。菌株z4在28 ℃、180 r/min的条件下培养72 h，所得果胶酶酶活为40.52 U/mL。菌株z4所产果胶酶的酶学特性进行研究，发现该菌株所产果胶酶的最适反应温度为45 ℃，果胶酶在30～40 ℃时稳定性较好；该酶的最适反应pH值为6.0，果胶酶在pH 5.0～6.0时具有较好的稳定性；以果胶为底物时的酶促反应米氏常数（Km）为1.60 mg/mL，其最大反应速率（Vmax）为100 mg/（mL·h）。

Isolation and identification of a pectinase-producing endophytic fungus from Phragmites australis and enzymatic property of pectinase

Using pectin as sole carbon source, the pectinase-producing strain was screened from Phragmites australis by cetyltrimethylamine bromide (CTAB) precipitation method, identified according to morphologic observation and internal transcribed space (ITS) sequence analysis, and the enzymatic characteristic of the pectinase produced by the strain was determined. The results showed that an endophytic fungus with high pectinase production ability was selected, namely z4. The strain z4 was identified as Aspergillus nomius. When the strain was cultured at 28 ℃ and 180 r/min for 72 h, the pectinase activity was 40.52 U/ml. The enzymatic properties of the pectinase produced by the strain z4 were studied. It was found that the optimum reaction temperature was 45 ℃, and the pectinase was stable at 30-40 ℃; the optimum pH value was 6.0, and the pectinase was stable at pH 5.0-6.0; the Michaelis constant (Km) of the enzymatic reaction with pectin as substrate was 1.60 mg/ml, and the maximum reaction rate (Vmax) was 100 mg/(ml·h).