A team of researchers in the University of Portsmouth have created a new “super enzyme” that can break down plastic up to six times faster than their previous enzyme. According to a press release, the scientists combined a previously re-engineered plastic-eating enzyme named PETase with a second enzyme to speed up the process.
The super enzyme could have major implications for recycling polyethylene terephthalate (PET), which is the most common thermoplastic used in single-use drinks bottles, carpets, and clothing. PET takes hundreds of years to degrade in the environment.
It is therefore remarkable that PETase can break it down into its building blocks in a few days.
This latest development represents a huge step towards using enzymes to recycle plastic and reduce plastic pollution.
“We were actually quite surprised it worked so well,” said John McGeehan, lead co-author and director of the Centre for Enzyme Innovation at the University of Portsmouth, although he underlined that the process is “still way too slow” to be commercially viable.
The researchers have received funding to carry out further experiments, and successful developments could mean existing PET could be recycled instead of using fossil fuels to create new plastic. This could amount to huge energy savings.
How does the Super Enzyme work?
The super enzyme is a combination of the previously engineering PETase and a second enzyme MHETase. This mixture of the 2 enzymes breaks down PET twice as fast as PETase could do on its own. Connecting the 2 eenzymes also increases the speed by a further three times. The team used the Diamond Light Source, a device that uses X-rays 10 billion times brighter than the Sun to be able to see individual atoms, to map the molecular structure of MHETase.
Then, the researchers were able to engineer the new super enzyme by connecting MHETase and PETase by effectively stitching the enzymes DNA together to create one long chain.
This is a technique that is commonly used in the biofuels industry, which uses enzymes to break down cellulases. However, this may be the first time that it is being used to break down plastic. The full study was published in the journal Proceedings of the National Academy of Sciences of the United States of America.
What other alternatives exist?
As the global plastic challenge grows bigger, scientists and researchers are making efforts to find alternatives to plastic and ways of dealing with plastic waste. According to a recent report from The Pew Charitable Trusts, it is projected that the volume of plastic entering the ocean could nearly triple to 29 million metric tons per year by 2040.
It also said that although there is “no single solution,” but “an ambitious recycling strategy” could slash 31-45% of plastic pollution.
French firm Carbios also announced the publication of a study into its own PET-eating enzyme, scheduled to be tested at a demonstration plant near the city of Lyon in 2021, according to a press release from the company.
Other possible solutions include the tiny waxworm, which can chomp through plastic, even polyethylene, a common and non-biodegradable plastic currently clogging up landfills and seas, thanks to its gut bacteria.
Mealworms, the larval stage of the mealworm beetle, could also contribute. Around 3,000-4,000 mealworms can break down one Styrofoam coffee cup in about a week thanks to the bacteria living in their gut.
It’s encouraging to see the efforts and research aimed at tackling the plastic pollution problem starting to yield fruits. With about 300 million tons of plastic produced each year, with most of it dedicated to single use items like plastic bottles, there still remains a lot to be done in order to tackle the plastic problem. Only 9% of all plastic ever created has been recycled with up to 8 million ending up in oceans each year.
While we support such efforts, we can continue to play our part by cutting our plastic use and consumption and choosing alternatives that are better for the earth and the environment. Minimize or eliminate the use of plastic straws, use a reusable carrier bag when you go shopping, pack your meals in reusable containers, invest in a reusable bottle for water and other drinks, and stop chewing gum, it is made of a synthetic rubber which is a type of plastic.
Everyone can make a positive difference!