一株土曲霉金色变种产生菊糖酶的研究

Studis on Inulinase Production by one terreus var. aureus Strain Fx-2

一株土曲霉金色变种(Aspergillus terreus var.aureus Fx-2),从土壤中分离出该菌株在培养基中添加 1.0％玉米浆,5.0％菊糖、发酵6d,可产生活性达55.3units/ml的菊糖酶(Inulinase)。这种酶能被菊糖(Inulin)所诱导,而不被蔗糖、棉子糖、纤维素、葡萄糖或果糖所诱导。酶对菊糖水解反应的最适pH4.5,最适温度55℃。在pH4.5～5.5内,30℃保持24h;或pH5.0,60℃保持 10 min,酶的活性均能维持稳定。2.0％菊糖溶液,在适宜条件下,7 h内底物几乎100％被酶水解。产物的总糖中,果糖占93.0％、葡萄糖占5.8％。这株土曲霉合成菊糖酶时,最适pH为4.0,生成的酶具有较满意的水解性能和对热稳定性能。

A mold, A. terreus var. aureus Fx-2, isolated from soil, was found to produce a high active inulin-hydrolyzing enzyme. The inulinase activity of this strain was induced by inulin, but not by sucrose, raffinose, celluose, glucose or fructose. The highest inulinase activity{55.3 units/ ml)was obtained under the optimum conditions. The hydrolysis of inulin by A. terreus var. aureus Fx-2 crude enzyme was investigated, and the product of hydrolysis of inulin was analyzed by high performance liquid chromatography. Aninulin suspension of 2.0%, was hydrolyzed completely at pH 5.0, 55℃, in 7 h. In total sugar of the hydrolysis product,93.0% fructose and 5.8% glucose Ware obtained. The optimum PH Was 4.0 for the enzyme production.and the enzyme had heat stability (60℃). The inulinase produced by A.terreus var.aurcus Fx-2 was a potential enzyme for high fructose syrup preparation from inulin containingagricutural crops.