采用硫酸铵分级沉淀、透析脱盐、DEAE-Cellulose离子交换色谱等分离纯化技术,从Aspergillus ficuum菌株混合酶系中分离得到4种菊粉酶组分,应用薄层层析法分离各组分水解菊粉的产物,发现其中3种组分主要含外切菊粉酶,一种主要含有内切菊粉酶。进一步对所得到的内切菊粉酶组分酶解菊粉制备低聚果糖进行了研究,研究了底物浓度、加酶量、反应温度和反应pH对低聚果糖制备的影响,确定其最适反应条件为:底物浓度50g/L、加酶量10U/g底物,反应温度45℃,反应PH6.0。在此条件下反应72h,菊粉酶解率达74%,低聚果糖得率可达50%以上,酶解产物以DP2~DP4为主。
The crude inulinase from Aspergillus ficuum was purified in a sequence of operations including ammonium sulfate fractionation, ion exchange chromatography on DEAE-Cellulose. Four highly purified enzymes were thus obtained. Three of them were identified as exoinulinase, and the rest one mainly contained endoinulinase. Preparation of inulooligosaccharides using the endoinulinase was studied. The optimal conditions for inulooligosaccharides preparation were established and shown as follows: 50 g/L inulin, enzyme concentraion of 10 U/g substrate, 45℃, and pH 6.0. The inulin-degrading degree was up to 74% and the inulo-oligosaccharides yield was over 50% after 72h of hydrolyzation. The major products were identified as DP2 to DP4.