Environmental pollution caused by plastic waste has become global problem that needs to be considered urgently. In the pursuit of a circular plastic economy, biodegradation provides an attractive strategy for managing plastic wastes, whereas effective plastic-degrading microbes and enzymes are required. In this study, we report that sp. G-9 isolated from discarded plastic in landfills is capable of depolymerizing polyurethanes (PU) and poly (butylene adipate-co-terephthalate) (PBAT). Strain G-9 degrades up to 60% of PU foam after 21 days of incubation at 28 ℃ by breaking down carbonyl groups via secretory hydrolase as confirmed by structural characterization of plastics and degradation products identification. Within the supernatant of strain G-9, we identify a novel cutinase BaCut1, belonging to the esterase family, that can reproduce the same effect. BaCut1 demonstrates efficient degradation toward commercial polyester plastics PU foam (0.5 mg enzyme/25 mg plastic) and agricultural film PBAT (0.5 mg enzyme/10 mg plastic) with 50% and 18% weight loss at 37 ℃ for 48 h, respectively. BaCut1 hydrolyzes PU into adipic acid as a major end-product with 42.9% recovery via ester bond cleavage, and visible biodegradation is also identified from PBAT, which is a beneficial feature for future recycling economy. Molecular docking, along with products distribution, elucidates a special substrate-binding modes of BaCut1 with plastic substrate analogue. BaCut1-mediated polyester plastic degradation offers an alternative approach for managing PU plastic wastes through possible bio-recycling.

中文翻译：

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来自 Blastobotrys sp. 的新型聚氨酯降解角质酶 BaCut1。 G-9 在塑料生物回收中具有潜在作用


塑料垃圾造成的环境污染已成为迫切需要考虑的全球性问题。在追求循环塑料经济的过程中，生物降解为管理塑料废物提供了一种有吸引力的策略，同时需要有效的塑料降解微生物和酶。在这项研究中，我们报告了 sp。从垃圾填埋场的废弃塑料中分离出的 G-9 能够解聚聚氨酯 (PU) 和聚己二酸-对苯二甲酸丁二醇酯 (PBAT)。塑料结构表征和降解产物鉴定证实，在 28℃ 下孵育 21 天后，菌株 G-9 通过分泌水解酶分解羰基，降解高达 60% 的 PU 泡沫。在菌株 G-9 的上清液中，我们鉴定出一种新型角质酶 BaCut1，属于酯酶家族，可以重现相同的效果。 BaCut1 表现出对商用聚酯塑料 PU 泡沫（0.5 毫克酶/25 毫克塑料）和农用薄膜 PBAT（0.5 毫克酶/10 毫克塑料）的有效降解，在 37℃ 下 48 小时分别失重 50% 和 18%。 BaCut1 将 PU 水解为己二酸作为主要最终产品，通过酯键断裂回收率达 42.9%，并且 PBAT 也具有明显的生物降解性，这对于未来的循环经济是一个有利的特征。分子对接以及产物分布阐明了 BaCut1 与塑料底物类似物的特殊底物结合模式。 BaCut1 介导的聚酯塑料降解提供了一种通过可能的生物回收来管理 PU 塑料废物的替代方法。