角质酶在生物可降解聚酯聚己二酸/对苯二甲酸丁二醇酯降解中的应用

Application of cutinase in the degradation of biodegradable polyester poly(butylene adipate-co-terephthalate)

摘要:

随着废弃塑料带来的环境污染越来越严重，生物可降解聚酯已成为大众关注的焦点。聚己二酸/对苯二甲酸丁二醇酯[poly(butylene adipate-co-terephthalate), PBAT]是脂肪族和芳香族共聚形成的生物可降解聚酯，兼具两者的优异性能。针对PBAT在自然条件下对降解环境要求严格且降解周期长的不足之处，本研究探究了角质酶在PBAT降解中的应用和对苯二甲酸-丁二醇酯(butylene terephthalate, BT)含量对PBAT生物降解性的影响，以实现对PBAT降解速率的提升。选取5种不同来源的聚酯降解酶对PBAT进行降解应用并比较出降解效果最优的酶，并测定了含有不同BT含量的PBAT聚酯的降解效率。结果表明，角质酶ICCG为降解效果最好的酶，且BT含量越高PBAT的降解率越低。此外，还确定了角质酶ICCG对高BT含量的PBAT(H)降解的最适温度、最适缓冲液类型、最适pH、最适E/S (enzyme to substrate)和最适底物浓度比分别为75 °C、Tris-HCl、9.0、0.4%和1.0%。本研究结果可为角质酶在PBAT降解中的应用提供一定的理论依据和实验参考。

Abstract:

With the environmental pollution caused by waste plastics becoming increasingly serious, biodegradable polyester has become the focus of public attention. Poly(butylene adipate-co-terephthalate) (PBAT) is a biodegradable polyester formed by the copolymerization of aliphatic and aromatic groups, which has excellent performance of both. The degradation of PBAT under natural conditions requires strict environmental conditions and long degradation cycle. To address these shortcomings, this study explored the application of cutinase in PBAT degradation and the impact of butylene terephthalate (BT) content on the biodegradability of PBAT, so as to improve the degradation rate of PBAT. Five Polyester degrading enzymes from different sources were selected to degrade PBAT to pick out the most efficient enzyme. Subsequently, the degradation rate of PBAT materials with different BT content were determined and compared. The results showed that cutinase ICCG was the best enzyme for PBAT biodegradation, and the higher the BT content, the lower the degradation rate of PBAT. Furthermore, the optimum temperature, buffer type, pH, the ratio of enzyme to substrate (E/S) and substrate concentration in the degradation system were determined to be 75 °C, Tris HCl, 9.0, 0.4% and 1.0% respectively. These findings may facilitate the application of cutinase in PBAT degradation.