利用醋酸纤维/聚四氟乙烯复合膜中的微结构固定化脂肪酶

脂肪酶的固定化是降低其使用成本的有效途径之一.提出了利用亲水/疏水复合膜中的微结构固定化脂肪酶的新思路.首先制备由致密的亲水层和多孔的疏水层组成的醋酸纤维素/聚四氟乙烯（CA/PTFE）复合膜，然后利用复合膜的特殊微结构，用超滤的方法实现了脂肪酶的固定化.扫描电镜照片结果表明，大部分被截留的酶位于复合膜的界面处.制备得到的固定化酶膜应用于水解橄榄油的反应，其最高催化活力达到1.24 μmol FFA·min^-1·cm^-2，大大高于文献报道值.同时研究了固定化脂肪酶膜的催化动力学，考察了亲水层厚度和脂肪酶负载量对固定化效果的影响，优化了固定化条件.在经过10次（50 h以上）的重复使用后，固定化酶膜的活力仅降低了20%.

Candida rugosa lipase immobilized by special microstructure in CA/PTFE composite membrane

The immobilization of lipase is helpful to lowering the cost of application of lipase.A special microstructure in the CA/PTFE composite membrane was proposed to immobilize Candida rugosa lipases.Firstly，the composite membrane was prepared through coating hydrophilic CA membrane with nanometer-sized pores on the hydrophobic PTFE membrane with micrometer-sized pores.By ultrafiltration of the enzyme solution，lipase was retained by the CA dense layer and was located on pores of PTFE layers and at the interface of CA and PTFE layers.SEM photos showed that most of immobilized lipase was located on the interface of composite membrane.Then immobilized enzyme membranes were used in biphasic enzyme membrane reactor（BEMR）for hydrolysis of olive oil.The effects of the thickness of CA layer and the lipase loading density on membrane bioreactor performance were investigated.Experimental results showed that the special microstructure in composite membrane could efficiently immobilize the lipase，and the maximum specific activity（1.24 μmol FFA·min^-1·cm^-2）was found to be higher than the value reported in literatures.The immobilized enzyme membrane was used for 10 times（5 h/times）with only 20% activity lost.