Cell Factory Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, 34141, Republic of Korea.
Department of Environmental Biotechnology, KRIBB School of Biotechnology, University of Science & Technology (UST), Daejeon, 34113, Republic of Korea.
Microb Cell Fact. 2020 Apr 28;19(1):97. doi: 10.1186/s12934-020-01355-8.
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.
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.
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.
几十年来，由于其便利性和低廉的价格，塑料已成为一种有价值的全球产品。例如，由于其有益的特性，例如抗冲击性、高清晰度和重量轻，聚对苯二甲酸乙二醇酯（PET）是最受欢迎的一次性瓶用材料之一。对塑料的需求不断增加导致消费者随意丢弃，造成塑料废物严重堆积。因此，科学家们一直在努力寻找一种生物处理塑料废物的方法。结果，2016 年在 Ideonella sakaiensis 201-F6 中发现了一种新型的塑料降解酶，即可以水解 PET 的 PETase。
本研究开发了一种能产生 PETase 的绿藻，衣藻。对两种代表性菌株（C. reinhardtii CC-124 和 CC-503）进行了检查，发现 CC-124 能够很好地表达 PETase。为了验证衣藻产生的 PETase 的催化活性，将转化体的细胞裂解物和 PET 样品在 30°C 下共孵育长达 4 周。孵育后，通过高效液相色谱分析检测到完全降解 PET 的产物对苯二甲酸（TPA）。此外，使用扫描电子显微镜观察到 PET 薄膜表面的形貌变化，如出现孔和凹痕。
成功地在衣藻中表达了 PET 水解酶 PETase，并证明了其催化活性。据我们所知，这是 PETase 在绿藻中首次表达的情况。
