BACKGROUND For decades, plastic has been a valuable global product due to its convenience and low price. For example, polyethylene terephthalate (PET) was one of the most popular materials for disposable bottles due to its beneficial properties, namely impact resistance, high clarity, and light weight. Increasing demand of plastic resulted in indiscriminate disposal by consumers, causing severe accumulation of plastic wastes. Because of this, scientists have made great efforts to find a way to biologically treat plastic wastes. As a result, a novel plastic degradation enzyme, PETase, which can hydrolyze PET, was discovered in Ideonella sakaiensis 201-F6 in 2016. RESULTS A green algae, Chlamydomonas reinhardtii, which produces PETase, was developed for this study. Two representative strains (C. reinhardtii CC-124 and CC-503) were examined, and we found that CC-124 could express PETase well. To verify the catalytic activity of PETase produced by C. reinhardtii, cell lysate of the transformant and PET samples were co-incubated at 30 °C for up to 4 weeks. After incubation, terephthalic acid (TPA), i.e. the fully-degraded form of PET, was detected by high performance liquid chromatography analysis. Additionally, morphological changes, such as holes and dents on the surface of PET film, were observed using scanning electron microscopy. CONCLUSIONS A PET hydrolyzing enzyme, PETase, was successfully expressed in C. reinhardtii, and its catalytic activity was demonstrated. To the best of our knowledge, this is the first case of PETase expression in green algae.

中文翻译：

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聚对苯二甲酸乙二醇酯降解酶（PETase）在绿色微藻中的功能表达。

背景技术数十年来，由于塑料的方便性和低廉的价格，其已成为有价值的全球产品。例如，聚对苯二甲酸乙二酯（PET）由于其有益的特性，即抗冲击性，高透明度和轻质性，成为一次性瓶最流行的材料之一。对塑料的需求不断增加，导致消费者随意处置，导致塑料废物严重堆积。因此，科学家们做出了巨大的努力，以寻找一种生物处理塑料废料的方法。结果，2016年在海德岛伊德氏菌201-F6中发现了一种新型的可降解PET的塑料降解酶PETase。结果本研究开发了一种绿藻，即产生PETase的莱茵衣藻。检查了两个代表性菌株（莱茵衣藻CC-124和CC-503），我们发现CC-124可以很好地表达PETase。为了验证莱茵衣藻产生的PET酶的催化活性，将转化子的细胞裂解物和PET样品在30℃下共孵育长达4周。孵育后，通过高效液相色谱分析检测对苯二甲酸（TPA），即PET的完全降解形式。另外，使用扫描电子显微镜观察形态变化，例如PET膜表面上的孔和凹痕。结论成功地在莱茵衣藻中表达了一种PET水解酶PETase，并证明了其催化活性。据我们所知，这是PETase在绿藻中表达的首例。将转化子的细胞裂解液和PET样品在30°C共同孵育4周。孵育后，通过高效液相色谱分析检测对苯二甲酸（TPA），即PET的完全降解形式。另外，使用扫描电子显微镜观察形态变化，例如PET膜表面上的孔和凹痕。结论成功地在莱茵衣藻中表达了一种PET水解酶PETase，并证明了其催化活性。据我们所知，这是PETase在绿藻中表达的首例。将转化子的细胞裂解液和PET样品在30°C共同孵育4周。孵育后，通过高效液相色谱分析检测对苯二甲酸（TPA），即PET的完全降解形式。另外，使用扫描电子显微镜观察形态变化，例如PET膜表面上的孔和凹痕。结论成功地在莱茵衣藻中表达了一种PET水解酶PETase，并证明了其催化活性。据我们所知，这是PETase在绿藻中表达的首例。使用扫描电子显微镜观察形态变化，例如PET膜表面的孔和凹痕。结论成功地在莱茵衣藻中表达了一种PET水解酶PETase，并证明了其催化活性。据我们所知，这是PETase在绿藻中表达的首例。使用扫描电子显微镜观察形态变化，例如PET膜表面的孔和凹痕。结论成功地在莱茵衣藻中表达了一种PET水解酶PETase，并证明了其催化活性。据我们所知，这是PETase在绿藻中表达的首例。