Scientists at the University of Texas at Austin wrote in the latest issue of nature that they have developed a new enzyme variant fast petase, which can decompose plastics that normally take hundreds of years to degrade in a few hours to a few days. It is expected to greatly promote the recycling of plastics and truly open the curtain of plastic circular economy**
Professor Hal Alper, the person in charge of the latest research, said that the new enzyme they developed is mainly aimed at polyethylene terephthalate (PET), which appears in most consumer product packaging, including biscuit boxes, soda bottles, fruit and salad packaging, as well as some fibers and textiles. It accounts for 12% of the total amount of waste in the world, and the amount may be as high as billions of tons.
In the latest research, Alper et al. Developed a new mutation of natural enzyme named petase with the help of machine learning model, predicted which mutations can quickly depolymerize waste plastics at low temperature, and then studied 51 different plastic containers, 5 different polyester fibers and fabrics, as well as all water bottles made of pet, proving the effectiveness of one of the enzymes named fast-petase.
The researchers point out that the new enzyme variant can complete a "circular process", breaking down the plastic into smaller parts (depolymerization) and then reassembling it chemically (repolymerization). In some cases, these plastics can be completely decomposed into monomers within 24 hours.
Recycling is the best way to reduce plastic waste, but globally, less than 10% of plastic is recycled. In addition to throwing plastic off the landfill site, the most common treatment method is to burn it, but this method is costly, energy consuming and will emit harmful gases into the air. Other alternative industrial processes include glycolysis, pyrolysis and / or methanol hydrolysis, but these treatment processes are also very energy consuming.
Biological solutions consume much less energy. In the past 15 years, scientists have been studying the recycling of plastics with enzymes and made some progress. But so far, no one has figured out how to make enzymes that can operate efficiently at low temperatures and can be better used on a large scale. The latest research confirms that fast petase can decompose plastics at temperatures below 50 degrees Celsius.
Next, the team plans to expand the production scale of the enzyme to prepare for industrial and environmental applications. The researchers said that the enzyme is expected to play an important role in waste treatment industries such as landfill cleaning. To this end, they are studying various methods to transport these enzymes to the wild to clean up contaminated sites.