渗透性K.lactis细胞内乳糖酶水解牛乳中乳糖的研究

Continuous Lactose Hydrolysis in Milk with Osmotic K.lactis Cells

应用填充床细胞反应器,以渗透性K．lactis细胞内乳糖酶连续催化牛乳中乳糖的水解。渗透性K．lactis细胞内乳糖酶的热失活遵循一级反应动力学,40℃时酶的半衰期为9．5h,表观米氏常数为0．39mmol/ml,最大反应速率V_(max)为0．188mmol/min。在2．6cm×50cm填充床生物反应器上,渗透性K．lactis细胞内乳糖酶催化牛乳中乳糖水解的适宜体积流速为1．0ml/min,酶反应的适宜温度40℃,反应速率达到动态平衡后生成的葡萄糖的质量浓度为45．2mg/ml,牛乳中乳糖的水解率为91．3%。

Osmotic K.lactis cells were packed into packed bed reactor to hydrolyze lactose in milk. The thermal inactivation of lactase entrapped in K.lactis cells followed the first-order kinetics, and its half-life was 9.5h at 40℃. Appearent Km constant and maximum reaction rate for the enzyme were 0.39 mmol/ml and 0.188 retool/rain, respectively. The optimal reaction parameters for hydrolysis of lactose in milk with osmotic K. lactis cells packed in 2,6 cmX 50 cm column are： flow rate 1.0 ml/min at 40 ℃. Under these conditions, hydrolyzed glucose concentration reaches 45.2 mg/ml.