壳聚糖固定化真菌漆酶及其用于处理酚类污染物的研究

Immobilization of Fungal Laccase on Chitosan and Its Use in Phenolic Effluents Treatment

Trametessp.AH2 8 2在液体培养条件下经邻甲苯胺诱导能有效合成漆酶同工酶A。以壳聚糖为载体 ,戊二醛为交联剂进行了漆酶A的固定化研究 ,确定酶固定化适宜条件为 :0 1g壳聚糖与 1 5mL 5 %戊二醛交联 8h后 ,加入 30 0U酶固定 1 2h。在此条件下获得的固定化漆酶催化能力为 1 76 4U g载体 ,酶活回收率 5 8 5 %。与游离酶相比 ,固定化漆酶与作用底物愈创木酚的亲和力降低 ,但固定化酶的稳定性有明显改善。固定化漆酶的最适温度为5 5℃ ,比游离酶提高 5℃ ;70℃条件下保温 8h ,固定化酶保留酶活 5 6 5 % ,而在相同条件下游离酶酶活明显下降。使用固定化漆酶反应装置进行酚类化合物转化实验 ,连续进行 1 2批次操作 ,固定化酶酶活仍保持 60 %以上 。

Laccase isozyme (Lac A) can be efficiently synthesized by Trametes sp. strain AH28 2 cultivated in liquid medium with the induction of o tolidine. Lac A was immobilized on chitosan by means of covalent coupling to a glutaradehyde pretreated support. The conditions of immobilization of Lac A were optimized, which could be specified as: 0 1 g chitosan and 5% glutaraldehyde 15mL crosslinked for 8 h, then added 30 0 U enzyme to immobilize for 12 h. In this way, 176 4 U/g of catalytic activity of immobilized enzyme was available, and the recovery of enzyme activity was 58 5%. Compared with the free enzyme, the affinity of immobilized enzyme decreased toward substrate guaiacol, but its stability was considerably improved. The optimal temperature for immobilized enzyme was 55℃, 5℃ higher than the free enzyme. 56 5% of initial enzyme activity could remained, if kept at a temperature of 70℃ for 8 h. Free enzyme would be greatly affected under the same conditions. The oxidation of phenolic compounds, carried out in the reaction system of immobilized enzyme, showed the activity of immobilized enzyme still remained over 60% after 12 cycles of operation. Thus the catalytic efficiency of laccase was greatly improved.