Present estimates suggest that of the 359 million tons of plastics produced annually worldwide¹, 150–200 million tons accumulate in landfill or in the natural environment². Poly(ethylene terephthalate) (PET) is the most abundant polyester plastic, with almost 70 million tons manufactured annually worldwide for use in textiles and packaging³. The main recycling process for PET, via thermomechanical means, results in a loss of mechanical properties⁴. Consequently, de novo synthesis is preferred and PET waste continues to accumulate. With a high ratio of aromatic terephthalate units—which reduce chain mobility—PET is a polyester that is extremely difficult to hydrolyse⁵. Several PET hydrolase enzymes have been reported, but show limited productivity^6,7. Here we describe an improved PET hydrolase that ultimately achieves, over 10 hours, a minimum of 90 per cent PET depolymerization into monomers, with a productivity of 16.7 grams of terephthalate per litre per hour (200 grams per kilogram of PET suspension, with an enzyme concentration of 3 milligrams per gram of PET). This highly efficient, optimized enzyme outperforms all PET hydrolases reported so far, including an enzyme^8,9 from the bacterium Ideonella sakaiensis strain 201-F6 (even assisted by a secondary enzyme¹⁰) and related improved variants^11,12,13,14 that have attracted recent interest. We also show that biologically recycled PET exhibiting the same properties as petrochemical PET can be produced from enzymatically depolymerized PET waste, before being processed into bottles, thereby contributing towards the concept of a circular PET economy.

目前的估计表明，在全球每年生产的 3.59 亿吨塑料¹中，有 150-2 亿吨塑料堆积在垃圾填埋场或自然环境中²。聚对苯二甲酸乙二醇酯 (PET) 是最丰富的聚酯塑料，全球每年生产近 7000 万吨用于纺织品和包装³。PET 的主要回收过程，通过热机械方式，导致机械性能的损失⁴。因此，从头合成是首选，PET 废物继续积累。具有高比例的芳族对苯二甲酸酯单元 - 降低了链的流动性 - PET 是一种极难水解的聚酯⁵. 已经报道了几种 PET 水解酶，但显示出有限的生产力^6,7。在这里，我们描述了一种改进的 PET 水解酶，它最终在 10 小时内将至少 90% 的 PET 解聚成单体，生产率为 16.7 克/升/小时（200 克/千克 PET 悬浮液，使用酶浓度为每克 PET 3 毫克）。这种高效、优化的酶优于迄今为止报道的所有 PET 水解酶，包括来自Ideonella sakaiensis菌株 201-F6 的酶^8,9（甚至由辅助酶¹⁰辅助）和相关的改进变体^11,12,13,14最近引起了人们的兴趣。我们还表明，具有与石化 PET 相同特性的生物回收 PET 可以由酶解聚 PET 废料生产，然后再加工成瓶子，从而有助于实现循环 PET 经济的概念。