Nature Chemical Biology：活塑料——通过合成生物学降解塑料的新解决方案-动脉网

Nature Chemical Biology：Living plastics——a new solution for plastic degradation through synthetic biology

D-Pharm 等信源发布 2024-09-02 13:10

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Dr. DAI Zhuojun's research group at the Shenzhen Institute of Advanced Technology (SIAT), Chinese Academy of Sciences (CAS), published a study titled 'Degradable Living plastics Programmed by Engineered Spores' in Nature Chemical Biology. The study leverages the natural resilience of spores, which can endure extreme environmental conditions, by programming them to secrete plastic-degrading enzymes under specific circumstances.

中国科学院深圳先进技术研究所（SIAT）戴卓军博士的研究小组在《自然化学生物学》上发表了一项题为“工程孢子编程的可降解生物塑料”的研究。这项研究利用孢子的天然弹性，孢子可以承受极端的环境条件，通过编程在特定情况下分泌塑料降解酶。

These spores are embedded into plastic matrices through standard plastic processing methods, such as high temperature, high pressure, or the use of organic solvents. In normal conditions, the spores remain dormant, ensuring the plastic's stable performance. However, when exposed to specific triggers like surface erosion or composting, the spores activate and initiate the degradation process, leading to the plastic's complete breakdown.

这些孢子通过标准的塑料加工方法嵌入塑料基质中，例如高温，高压或使用有机溶剂。在正常情况下，孢子保持休眠状态，确保塑料的稳定性能。然而，当暴露于表面侵蚀或堆肥等特定触发因素时，孢子会激活并启动降解过程，导致塑料完全分解。

Plastics are widely used but difficult to degrade, posing an ecological challenge. A team from SIAT developed degradable 'living plastics' using synthetic biology and polymer engineering. They engineered Bacillus subtilis spores to produce Burkholderia cepacia lipase (BC-lipase), an enzyme that breaks down plastic.

塑料被广泛使用，但很难降解，这对生态构成了挑战。。

These spores were mixed with poly(caprolactone) (PCL) to create the plastics, maintaining the material's physical properties. When the plastic surface is eroded, the spores release the enzyme, leading to nearly complete breakdown of the plastic..

将这些孢子与聚己内酯（PCL）混合以产生塑料，保持材料的物理性质。当塑料表面被侵蚀时，孢子释放出酶，导致塑料几乎完全分解。。

DAI Zhuojun

戴卓军

Research Background

研究背景

The invention of plastics has improved our daily lives, but the massive production and improper disposal of plastic waste have made plastic pollution a major environmental issue. In 2016, Yoshida et al. discovered a bacterium, Ideonella sakaiensis, in poly (ethylene terephthalate) (PET)-contaminated soil near a recycling facility in Japan.

塑料的发明改善了我们的日常生活，但塑料废物的大量生产和不当处理使塑料污染成为一个主要的环境问题。。

This bacterium can grow using PET as its main carbon source by producing two key enzymes: PETase and MHETase. Since then, numerous synthetic biology research has been focusing on discovering, designing and evolving the relevant plastic-degrading enzymes, there has been little exploration of innovative methods for creating degradable plastics.

这种细菌可以使用PET作为主要碳源，通过产生两种关键酶：PETase和MHETase来生长。从那时起，许多合成生物学研究一直专注于发现，设计和进化相关的塑料降解酶，很少探索创造可降解塑料的创新方法。

Dormant Spores and Living Plastics

休眠孢子和活塑料

Microorganisms have developed intrinsic mechanism to defend harsh conditions over billions of years. One classical example is the formation of spores that are resilient to dryness, high temperatures and high pressure (similar conditions in plastics processing). Using synthetic biology, the research team engineered Bacillus subtilis with a genetic circuit to control the secretion of a plastic-degrading enzyme (lipase BC from Burkholderia cepacia).

数十亿年来，微生物已经发展出防御恶劣条件的内在机制。一个典型的例子是孢子的形成，孢子对干燥，高温和高压（塑料加工中的类似条件）具有弹性。利用合成生物学，该研究小组设计了具有遗传回路的枯草芽孢杆菌，以控制塑料降解酶（洋葱伯克霍尔德氏菌脂肪酶BC）的分泌。

Under stress from heavy metal ions, Bacillus subtilis forms spores. The team mixed these engineered spores with poly (caprolactone) (PCL) plastic granules and produced spore-containing plastics through high-temperature extrusion or solvent dissolution. Tests showed that these 'living plastics' had similar physical properties to regular PCL plastics.

在重金属离子的胁迫下，枯草芽孢杆菌形成孢子。该团队将这些工程孢子与聚己内酯（PCL）塑料颗粒混合，通过高温挤出或溶剂溶解产生含孢子的塑料。测试表明，这些“活性塑料”具有与常规PCL塑料相似的物理性能。

During daily use, the spores remain dormant, ensuring the plastic's stable performance. .

在日常使用中，孢子保持休眠状态，确保塑料的稳定性能。

Spore Release and Degradation Initiation

孢子释放和降解起始

The first key step in plastic degradation is to release the spores embedded in the living plastic for cell reviving. Researchers have first demonstrated two methods of spore release. One method uses an enzyme (lipase CA) to erode the plastic surface. These released spores then germinated and expressed the lipase BC, which bound to the ends of PCL polymer chains and near-completely degraded the PCL molecules (final molecular weight <500 g/mol).

塑料降解的第一个关键步骤是释放嵌入活塑料中的孢子以使细胞复活。研究人员首先展示了两种孢子释放方法。一种方法是使用酶（脂肪酶CA）腐蚀塑料表面。然后，这些释放的孢子发芽并表达脂肪酶BC，脂肪酶BC与PCL聚合物链的末端结合并几乎完全降解PCL分子（最终分子量<500 g/mol）。

The results showed that living plastic could degrade efficiently within 6-7 days, while ordinary PCL plastic subjected only to surface damage (lipase CA) still had a large amount of plastic debris after 21 days. .

结果表明，活性塑料在6-7天内可以有效降解，而仅受到表面损伤的普通PCL塑料（脂肪酶CA）在21天后仍有大量塑料碎片。

Another method for spores releasing is composting. In the absence of any additional exogenous agents, living plastics in soil could completely degrade within 25-30 days, while traditional PCL plastic took about 55 days to degrade to a level that was invisible to the naked eye.

另一种释放孢子的方法是堆肥。在没有任何额外外源剂的情况下，土壤中的活塑料可以在25-30天内完全降解，而传统的PCL塑料需要大约55天才能降解到肉眼看不见的水平。

Beyond PCL Plastics

超越PCL塑料

As mentioned earlier, PCL's processing conditions are relatively 'mild' among plastics. To verify the system's general applicability, the team continued to testing other commercial plastic systems. They mixed spores carrying GFP expression plasmids with PBS (polybutylene succinate), PBAT (polybutylene adipate-co-terephthalate), PLA (polylactic acid), PHA (polyhydroxyalkanoates), and even PET (poly (ethylene terephthalate)) and processed the mixture at temperatures as high as 300oC.

如前所述，PCL的加工条件在塑料中相对“温和”。为了验证该系统的普遍适用性，该团队继续测试其他商业塑料系统。他们将携带GFP表达质粒的孢子与PBS（聚丁二酸丁二醇酯），PBAT（聚己二酸丁二醇酯-共-对苯二甲酸酯），PLA（聚乳酸），PHA（聚羟基链烷酸酯），甚至PET（聚对苯二甲酸乙二醇酯））混合，并在高达300℃的温度下处理混合物。

By releasing the spores through physical grinding, they surprisingly found that the spores could still revive and expressed the GFP. These results have laid a solid foundation for extending the method with other types of plastics. .

通过物理研磨释放孢子，他们惊讶地发现孢子仍然可以复活并表达GFP。这些结果为将该方法扩展到其他类型的塑料奠定了坚实的基础。

To validate the potential for scaling up the system, the research team also conducted a small-scale industrial test on PCL system using a single-screw extruder. The generated living PCL still exhibited rapid and efficient degradation property (degrade within 7 days). In the absence of external factors, the living PCL maintained a stable shape, demonstrating its robustness during the service (stable in Sprite for two months).

为了验证扩大系统规模的潜力，研究团队还使用单螺杆挤出机对PCL系统进行了小型工业测试。产生的活PCL仍然表现出快速有效的降解特性（在7天内降解）。在没有外部因素的情况下，活体PCL保持了稳定的形状，证明了其在服务期间的稳健性（在雪碧中稳定了两个月）。

This study provides a novel method for fabricating green plastics that can function steadily when the spores are latent and decay when the spores are aroused and sheds light on the development of materials for sustainability. .

这项研究为制造绿色塑料提供了一种新方法，当孢子潜伏时，绿色塑料可以稳定工作，当孢子被激发时，绿色塑料可以腐烂，并为可持续性材料的开发提供了启示。

Original publication

原始出版物

Chenwang Tang, Lin Wang, Jing Sun, Guangda Chen, Junfeng Shen, Liang Wang, Ying Han, Jiren Luo, Zhiying Li, Pei Zhang, Simin Zeng, Dianpeng Qi, Jin Geng, Ji Liu, Zhuojun Dai; 'Degradable living plastics programmed by engineered spores'; Nature Chemical Biology, 2024-8-21

唐晨旺、王林、孙静、陈光大、沈俊峰、王亮、韩英、罗继仁、李志英、张培、曾思敏、齐殿鹏、金庚、刘吉、戴卓军；'由工程孢子编程的可降解生物塑料；自然化学生物学，2024-8-21

https://www.bionity.com/en/news/1184323/living-plastics-a-new-solution-for-plastic-degradation-through-synthetic-biology.html

Plastic-eating enzyme could eliminate billions of tons of landfill waste

“This work really demonstrates the power of bringing together different disciplines, from synthetic biology to chemical engineering to artificial intelligence”

“这项工作真正证明了将不同学科结合在一起的力量，从合成生物学到化学工程再到人工智能”

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