透性化嗜酸乳杆菌细胞转化亚油酸为共轭亚油酸的反应动力学

Kinetics of bioconversion of linoleic acid to conjugated linoleic acid by permeabilized Lactobacillus acidophilus cells

摘要:

本实验旨在研究透性化嗜酸乳杆菌细胞生物转化共轭亚油酸的反应动力学。探讨了细胞浓度、底物浓度、反应体系pH值和温度等因素对生物转化共轭亚油酸反应速度的影响；建立了透性化嗜酸乳杆菌细胞生物转化共轭亚油酸的动力学模型。结果表明，透性化嗜酸乳杆菌细胞有利于共轭亚油酸的生物转化，最适细胞浓度、pH值和反应温度分别为10×1010 ufc/mL、4.5和45℃；生物转化共轭亚油酸存在底物抑制现象，当亚油酸的浓度为0.6 mg/mL时，反应速度达到最大值17.8 μg/(mL?min)。在低亚油酸浓度下，反应初始阶段的反应规律与经典米氏方程相符，而在高亚油酸浓度下，存在底物抑制现象。在最适反应条件下建立了动力学模型，模型基本反映了共轭亚油酸的生物转化特性。

Abstract:

In this study, we analyzed the kinetics of bioconversion of conjugated linoleic acid (CLA) by permeabilized Lactobacillus acidophilus cells. The effects of cell mass, linoleic acid (LA) concentration, reaction pH and temperature on the bioconversion of CLA by permeabilized cells were investigated and the model system of bioconversion of CLA was established. The results showed that the production of CLA was increased by permeabilized cells. The optimal cell mass, pH and temperature of bioconversion of CLA were 10×1010 ufc/mL, 4.5 and 45°C, respectively. A marked LA inhibition phenomenon existed, and the early reaction rate of producing CLA reached the maximum (17.8 μg/mL?min) when LA concentration was 0.6 mg/mL. Michaelis constant was obtained by double-reciprocal plot and Hanes-Woolf plot. The reaction rate equation followed the classic Michaelis-Mentent equation at the low LA concentration, while there was a marked LA inhibition phenomenon at the high LA concentration. With the evaluated model parameters, the model system appeared to provide a description for the bioconversion of CLA by permeabilized Lactobacillus acidophilus cells.