Recently, nature published a paper by Professor Hal Alper's team at the University of Texas at Austin, which discussed that the transformation of an enzyme with the help of machine learning can shorten the degradation time of plastics in centuries to 24 hours to a few days. This news has aroused concern because this achievement may solve a century old problem: limiting and reducing the harm of plastics to human society, nature and ecology.
The invention of plastics and the iterative renewal of plastic products are an innovation for human beings to use the earth's resources to develop economy and improve life. It is undoubtedly a great invention. However, 100 years after the invention of the plastic bag, the European environmental protection organization rated it as "the worst invention of mankind in the 20th century". The harm of plastic to people, organisms and the environment is becoming more and more serious.
Every year, the global production of plastics reaches a staggering 300 million tons. However, when the mission of plastic products ends, mankind can not effectively deal with them. Burning plastics will cause environmental hazards, such as a large number of dioxins and other pollutants. Once they enter the soil, they will also endanger plants, crops and ecology. At the same time, nearly 80% of the world's plastic products are sent to landfills and garbage dumps after the end of their mission, which not only pollutes local soil and water sources, but also appears in human blood, feces and even placenta in the form of micro plastics through drinking water and food chain.
Various measures have been put forward internationally to limit the harm caused by plastic products. The methods are: limiting the production and use of plastic products, adopting substitutes, recycling plastic products, making plastics enter recyclable mode, etc. China implemented the "plastic restriction order" in 2008, which stipulates that the production, sale and use of plastic shopping bags with a thickness of less than 0.025 mm are prohibited throughout the country. All supermarkets, shopping malls, market fairs and other commodity retail places are not allowed to provide plastic shopping bags free of charge. In 2020, many provinces and cities across the country also issued upgraded local regulations on "plastic limit".
Nevertheless, people still find that plastic products can't help it. While meeting people's needs, it has created many economic and social benefits. The global annual output of plastics can increase from 5 million tons in the 1950s to 300 million tons at present. The reason is that plastics are cheap and good, extremely durable and widely used.
To improve the output and utilization rate of a product, we can think of ways from the source and end. Now it seems that banning the production and use of plastic products seems unrealistic. We should find a way out for it - recycling.
Technology offers a possibility to provide exports for plastics to be degraded and recycled. Previous studies have found that petase enzyme can degrade pet (polyethylene terephthalate), but it also has obvious defects. It can only work in a specific pH and temperature range, and the reaction speed is limited. The plastic needs to be pretreated before degradation. Now, the research team at the University of Texas at Austin has used the machine learning model to transform petase and developed a new enzyme: fast-petase (functional, active, stable and tolerant petase), which can depolymerize and degrade pet into small molecules under a series of different pH conditions below 50 ℃. Under some conditions, these plastics can be completely degraded into monomers in only 24 hours.
Therefore, this also provides several ways for plastics to degrade plastics rapidly. This enzyme can also be used to repair the environment, clean up polluted areas, and help enterprises recycle plastics at the molecular level.
Technology provides new possibilities for the future of plastics. We hope that with the support of science and technology, the earth will return to green again.
