Key Laboratory for Waste Plastics Biocatalytic Degradation and Recycling, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, China.
Institute of Veterinary Immunology & Engineering, Jiangsu Academy of Agricultural Sciences, Nanjing, China.
Appl Environ Microbiol. 2024 Apr 17;90(4):e0147723. doi: 10.1128/aem.01477-23. Epub 2024 Mar 6.
Plastic degradation by biological systems emerges as a prospective avenue for addressing the pressing global concern of plastic waste accumulation. The intricate chemical compositions and diverse structural facets inherent to polyurethanes (PU) substantially increase the complexity associated with PU waste management. Despite the extensive research endeavors spanning over decades, most known enzymes exhibit a propensity for hydrolyzing waterborne PU dispersion (i.e., the commercial Impranil DLN-SD), with only a limited capacity for the degradation of bulky PU materials. Here, we report a novel cutinase (CpCut1) derived from sp. P7, which demonstrates remarkable efficiency in the degrading of various polyester-PU materials. After 12-h incubation at 55°C, CpCut1 was capable of degrading 40.5% and 20.6% of thermoplastic PU film and post-consumer foam, respectively, while achieving complete depolymerization of Impranil DLN-SD. Further analysis of the degradation intermediates suggested that the activity of CpCut1 primarily targeted the ester bonds within the PU soft segments. The versatile performance of CpCut1 against a spectrum of polyester-PU materials positions it as a promising candidate for the bio-recycling of waste plastics.IMPORTANCEPolyurethane (PU) has a complex chemical composition that frequently incorporates a variety of additives, which poses significant obstacles to biodegradability and recyclability. Recent advances have unveiled microbial degradation and enzymatic depolymerization as promising waste PU disposal strategies. In this study, we identified a gene encoding a cutinase from the PU-degrading fungus sp. P7, which allowed the expression, purification, and characterization of the recombinant enzyme CpCut1. Furthermore, this study identified the products derived from the CpCut1 catalyzed PU degradation and proposed its underlying mechanism. These findings highlight the potential of this newly discovered fungal cutinase as a remarkably efficient tool in the degradation of PU materials.
生物系统对塑料的降解为解决塑料废物积累这一紧迫的全球问题提供了有前景的途径。聚氨酯（PU）复杂的化学成分和多样的结构特征极大地增加了其废物管理的复杂性。尽管数十年来进行了广泛的研究，但大多数已知的酶都倾向于水解水性 PU 分散体（即商业 Impranil DLN-SD），而对大块 PU 材料的降解能力有限。在这里，我们报告了一种来自 sp. P7 的新型角质酶（CpCut1），它在降解各种聚酯-PU 材料方面表现出了显著的效率。在 55°C 下孵育 12 小时后，CpCut1 分别能够降解热塑性 PU 薄膜和消费后泡沫的 40.5%和 20.6%，同时完全解聚 Impranil DLN-SD。对降解中间体的进一步分析表明，CpCut1 的活性主要针对 PU 软段中的酯键。CpCut1 对各种聚酯-PU 材料的多功能性能使其成为废塑料生物回收的有前途的候选物。
重要性：聚氨酯（PU）的化学成分复杂，通常包含各种添加剂，这对其生物降解性和可回收性构成了重大障碍。最近的进展揭示了微生物降解和酶促解聚是有前途的废 PU 处理策略。在这项研究中，我们从 PU 降解真菌 sp. P7 中鉴定出一个编码角质酶的基因，该基因允许表达、纯化和表征重组酶 CpCut1。此外，本研究还确定了 CpCut1 催化 PU 降解产生的产物，并提出了其潜在的机制。这些发现突出了这种新发现的真菌角质酶作为一种高效工具在降解 PU 材料方面的潜力。
