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

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。

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 ℃-50 ℃ and 7.0, respectively. The enzyme activity still remained 68% when the enzyme was treated at 50 ℃ 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 Zn^2＋, Co^2＋, Ba^2＋, K^＋, and Ca^2＋ which has the most significant effect on the enzyme activity to improve 31% of activity. But, Mn^2＋ and EDTA could inhibite the enzyme activity.