Nature: Plastics can be completely degraded in as little as one day

Nature: Plastics can be completely degraded in as little as one day

“Nature”: Plastics can be completely degraded in the shortest day to meet a major breakthrough in the pollution problem.

Every year, a staggering 300 million tons of plastic are produced globally, but when they end their mission, what to do with these stable polymers becomes a challenge.

All over the world, billions of tons of plastic waste are buried in landfills, polluting local soil and water sources, and can also appear in human blood, feces and even placenta in the form of microplastics…

How to alleviate the increasingly severe plastic crisis has become an extremely urgent challenge.

In this regard, scientists are also looking for innovative countermeasures.

Last year, a Nature paper led to an important breakthrough: a research team at the University of California, Berkeley, invented a biodegradable plastic: under composting conditions of 40°C, the plastic can be degraded in just two days.

A year later, another Nature paper offered a solution from a different angle.

Using machine learning , Professor Hal Alper’s team at the University of Texas at Austin has engineered an enzyme that can reduce the degradation time of plastics measured in centuries to hours to days.

This key issue related to the future of mankind has ushered in the hope of cracking.

Globally, less than 10% of plastic is recycled. In the past ten years, a lot of progress has been made in the research on enzymes that degrade plastics.

But an open question is how to make enzymes that work efficiently at low temperatures, allowing for low-cost large-scale industrial applications.

What this study was trying to degrade was polyethylene terephthalate (PET), which is found in the vast majority of the plastic packaging we use every day.

PET accounts for 12% of the global solid waste.

If it can be quickly degraded by enzymes and then polymerized or converted into other products, it is expected to realize a circular carbon economy and greatly reduce environmental pollution.

In nature, an enzyme called PETase can degrade PET, but it also has obvious drawbacks: it can only work within a specific pH and temperature range, and the reaction speed is limited, and the plastic needs to be pretreated before degradation.

In this study, Professor Alper’s team used machine learning models to transform PETase.

The machine learning model could predict which mutations would allow PETase to rapidly degrade discarded plastic products at low temperatures.

Under the guidance of the model, the research team finally engineered a brand new enzyme: FAST-PETase (Functional, Active, Stable and Tolerant) PETase).

This enzyme can depolymerize and degrade PET into small molecules at temperatures below 50°C under a range of different pH conditions.

Under some conditions, these plastics can be completely degraded to monomers in as little as 24 hours.

To examine the effectiveness of FAST-PETase in degrading different PET plastic products, this study used FAST-PETase to degrade 51 untreated PET plastic products, including various plastic containers, polyester fibers, and fabrics.

As a result, all plastics were completely degraded within a week, and the fastest only took 1-2 days.

The enzyme could help companies recycle and reuse plastics at the molecular level, thereby reducing their adverse impact on the environment. “With this state-of-the-art recycling technology, industries can see endless possibilities,” Professor Alper said.

Next, the research team plans to scale up the production of FAST-PETase to lay the foundation for further industrial applications. The team is looking at several different uses: not just cleaning up plastic from landfills and making industrial production greener, but also using the enzyme for environmental remediation and cleaning up polluted areas.

Because of plastic pollution, the beautiful blue planet is turning a worrying white. Now, the birth of these emerging technologies promises to turn the plastic pollution crisis around. We look forward to the planet returning to its original, most beautiful color.

References:

[1] Lu， H。， Diaz， D.J。， Czarnecki， N.J。 et al。 Machine learning-aided engineering of hydrolases for PET depolymerization。 Nature 604， 662–667 （2022）。 https://doi.org/10.1038/s41586-022-04599-z

[2] Plastic-eating enzyme could eliminate billions of tons of landfill waste。 Retrieved Apr 27th， 2022 from https：//www.eurekalert.org/news-releases/950900

“Nature”: Plastics can be completely degraded in the shortest day to meet a major breakthrough in the pollution problem.