Researchers have found two enzymes in the saliva of waxworms that naturally break down ordinary plastic within hours at room temperature.
Polyethylene is one of the most widely used plastics in the world, being used in everything from food containers to shopping bags. Unfortunately, its toughness also makes it a persistent pollutant—the polymer must be processed at high temperatures to initiate the degradation process.
Waxworm saliva contains the only enzyme known to act on unprocessed polyethylene, making these naturally occurring proteins potentially very useful for recycling.
Molecular biologist and amateur beekeeper Federica Bertocchini accidentally discovered the ability of wax worms to degrade plastic a few years ago.
“At the end of the season, beekeepers usually deposit a few empty hives to return to the field in the spring,” Bertocchini recently told AFP.
She cleaned the hive and placed all the wax worms in plastic bags. Returning after a while, she found that the bag was “leaky”.
Waxwings (Galleria mellonella) are larvae that turn into short-lived wax moths over time. At the larval stage, the worms settle in the hive, feeding on beeswax and pollen.
Following this happy discovery, Bertocchini and her team at the Center for Biological Research Margherita Salas in Madrid set about analyzing waxworm saliva and published their results in Nature Communications.
The researchers used two methods: gel permeation chromatography, which separates molecules based on their size, and gas chromatography-mass spectrometry, which identifies molecular fragments based on their mass-to-charge ratio.
They confirmed that saliva does break down the long hydrocarbon chains of polyethylene into smaller, oxidized chains.
They then used proteomic analysis to identify a “handful of enzymes” in saliva, two of which have been shown to oxidize polyethylene, the researchers write.
The researchers named the enzymes “Demeter” and “Ceres” after ancient Greek and Roman goddesses of agriculture, respectively.
”To our knowledge, these polyvinylases are the first enzymes capable of performing such modifications to polyethylene films at room temperature in a short period of time,” the researchers write.
They added that because the two enzymes overcome “the first and most difficult step in the degradation process,” the process could represent an “alternative paradigm” for waste management.
Bertocchini told AFP that while the investigation is at an early stage, the enzymes may have been mixed with water and poured onto plastic at recycling facilities. They can be used in remote areas without garbage chutes or even in individual households.
Microbes and bacteria in the ocean and soil are evolving to feed on plastic, according to a 2021 study.
In 2016, researchers reported that a bacterium was found in a landfill in Japan that breaks down polyethylene terephthalate (also known as PET or polyester). This later inspired scientists to create an enzyme that could quickly break down plastic drink bottles.
About 400 million tons of plastic waste is generated annually in the world, about 30% of which is polyethylene. Only 10% of the 7 billion tons of waste generated in the world has been recycled so far, leaving a lot of waste left in the world.
Reducing and reusing materials will no doubt reduce the impact of plastic waste on the environment, but having a clutter cleaning toolkit can help us solve the problem of plastic waste.
Post time: Aug-07-2023
