Using a marine microalga as a chassis for polyethylene terephthalate (PET) degradation
Using a marine microalga as a chassis for polyethylene terephthalate (PET) degradation
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DOI：
10.1186/s12934-019-1220-z
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发表时间：
2019-10-10
影响因子：
6.4
通讯作者：
Maier, Uwe G.
中科院分区：
文献类型：
--
作者：
Moog, Daniel;Schmitt, Johanna;Maier, Uwe G.
背景资料：塑料的生物降解是一种很有前途的方法，可以对抗人造聚合物对我们星球日益严重的污染，并制定生态友好的回收策略。聚对苯二甲酸乙二醇酯（PET）是一种热塑性塑料，自20世纪40年代以来，工业上从化石原料生产，现在主要用于瓶包装和纺织品。尽管PET回收的工业过程已经建立，但大量的PET仍然最终进入环境-其中很大一部分进入世界海洋。2016年，分离出了一种能够降解PET并将降解产物用作生长唯一碳源的细菌Ideonella sakaiensis。I. sakaiensis表达负责PET分解成单体的关键酶：PET酶。这种水解酶可能具有巨大的潜力，为发展生物PET降解和回收过程以及环境塑料废物的生物修复方法。结果：使用光合作用的microphaeodactylum三角褐指藻作为底盘，我们产生了一个微生物细胞工厂能够生产和分泌到周围的培养基中的工程版本的PETase。在30 ° C下使用培养物上清液的初始降解实验表明，PETase对PET和共聚物聚对苯二甲酸乙二醇酯（PETG）具有活性，与瓶PET相比，低结晶度PETG的转化率高约80倍。此外，我们表明，硅藻产生的PETase对工业粉碎的PET在盐水为基础的环境中，即使在中温温度（21摄氏度）是积极的。从PET基板的降解所产生的产品主要是对苯二甲酸（TPA）和单（2-羟乙基）对苯二甲酸（MHET）估计形成的微摩尔范围内选定的反应conditions.Conclusion：我们提供了一个有前途的和生态友好的解决方案，通过使用真核微生物，而不是一个细菌作为模型系统的生物分解PET废物在盐水为基础的环境。我们的研究结果表明，通过合成生物学的硅藻三角褐指藻确实可以转化为生物PET降解的有价值的底盘。总的来说，这证明了原则的研究表明，硅藻系统的生物PET降解，特别是PET污染的海水的生物修复方法的未来生物技术应用的潜力。
Background: The biological degradation of plastics is a promising method to counter the increasing pollution of our planet with artificial polymers and to develop eco-friendly recycling strategies. Polyethylene terephthalate (PET) is a thermoplast industrially produced from fossil feedstocks since the 1940s, nowadays prevalently used in bottle packaging and textiles. Although established industrial processes for PET recycling exist, large amounts of PET still end up in the environment-a significant portion thereof in the world's oceans. In 2016, Ideonella sakaiensis, a bacterium possessing the ability to degrade PET and use the degradation products as a sole carbon source for growth, was isolated. I. sakaiensis expresses a key enzyme responsible for the breakdown of PET into monomers: PETase. This hydrolase might possess huge potential for the development of biological PET degradation and recycling processes as well as bioremediation approaches of environmental plastic waste.Results: Using the photosynthetic microalga Phaeodactylum tricornutum as a chassis we generated a microbial cell factory capable of producing and secreting an engineered version of PETase into the surrounding culture medium. Initial degradation experiments using culture supernatant at 30 degrees C showed that PETase possessed activity against PET and the copolymer polyethylene terephthalate glycol (PETG) with an approximately 80-fold higher turnover of low crystallinity PETG compared to bottle PET. Moreover, we show that diatom produced PETase was active against industrially shredded PET in a saltwater-based environment even at mesophilic temperatures (21 degrees C). The products resulting from the degradation of the PET substrate were mainly terephthalic acid (TPA) and mono(2-hydroxyethyl) terephthalic acid (MHET) estimated to be formed in the micromolar range under the selected reaction conditions.Conclusion: We provide a promising and eco-friendly solution for biological decomposition of PET waste in a saltwater-based environment by using a eukaryotic microalga instead of a bacterium as a model system. Our results show that via synthetic biology the diatom P. tricornutum indeed could be converted into a valuable chassis for biological PET degradation. Overall, this proof of principle study demonstrates the potential of the diatom system for future biotechnological applications in biological PET degradation especially for bioremediation approaches of PET polluted seawater.