产β-甘露聚糖酶内生菌的筛选及酶学特性分析

Screening of endophyte strain producing β-mannanase and the analysis of its enzymatic properties

摘要:

采用富集培养的方法从黄豆种子中分离出17株内生菌菌株, 利用刚果红染色法筛选出3株产β-甘露聚糖酶的内生菌。摇瓶培养并分别测定其酶活力, 其中一株酶活力较高, 达54.59 U/mL。经生理生化性质测定及16S rDNA序列分析, 鉴定为枯草芽孢杆菌Bacillus subtilis。酶学性质分析发现, 该酶最适作用温度和pH分别为30 °C?50 °C和7.0, 在50 °C保温2 h酶活仍保留68%, pH 5.0?9.0条件下保温1 h酶活仍保留64%以上; Zn2+、Ca2+、Co2+、Ba2+、K+对该酶有激活作用, 其中以Ca2+的激活作用最为明显, 使酶活提高了31%, Mn2+和EDTA对该酶有抑制作用。

Abstract:

Seventeen endophtye strains were isolated from soybean seeds by enrichment culture, and three endophyte strains producing β-mannanase were screened using Congo red dye method. By the shaking-flask culture, a strain of bacterium with the highest enzyme activity of 54.59 U/mL was obtained, and it was identified as Bacillus subtilis by the analysis of morphological, physiological and biochemical characteristics and 16S rDNA sequences. Enzymic properties of the β-mannanase revealed that the optimal temprature and pH were 30 °C?50 °C and 7.0, respectively. The enzyme activity still remained 68% when the enzyme was treated at 50 °C for 2 h; and more than 64% enzyme activity was remained after 1 h treatment at pH 5.0?9.0. In addition, the enzyme can be activated by Zn2+, Co2+, Ba2+, K+, and Ca2+ which has the most significant effect on the enzyme activity to improve 31% of activity. But, Mn2+ and EDTA could inhibite the enzyme activity.