A wax worm on a piece of plastic with holes César Hernández / CSIC
Plastic pollution may have met its unlikely match: the saliva of wax worms.
In a study published Tuesday in the journal Nature Communications, researchers discovered that enzymes in the saliva of wax worms can readily degrade polyethylene, a common form of plastic used in bags and other packaging materials.
Wax worms, or moth larvae that live in the honeycombs of beehives, have two enzymes in their saliva that break down the plastic at room temperature within just a few hours, according to the study.
The initial discovery came about as an accident in 2017, when Federica Bertocchini, a study author and amateur beekeeper, was tending to her hives.
“My beehives were plagued with wax worms, so I started cleaning them, putting the worms in a plastic bag,” Bertocchini, a molecular biologist at the Center for Biological Research in Spain, tells The Guardian’s Damian Carrington. “After a while, I noticed lots of holes, and we found it wasn’t only chewing—it was [chemical breakdown]. So that was the beginning of the story.”
Building on that realization, the new study pins down what researchers didn’t understand before: how exactly the insects accomplish this feat. The key was in the wax worms’ saliva. Their enzymes, or proteins that speed chemical reactions, allowed the insects to chemically break down the polyethylene.
To the best of the researchers’ knowledge, these are the first known animal enzymes with the ability to degrade plastic, per the paper. This introduces new solutions to the world’s plastic pollution problem through “bio-recycling,” in which organisms break down waste materials and create new products from them.
“Plastics stay in the environment for a long time,” Bertocchini tells Reuters’ Will Dunham. “It eventually breaks down into small particles, therefore becoming the source of micro and nano plastic particles. These plastic particles have been found everywhere, from Antarctica to rain and tap water, which do not only cause obvious environmental issues but are a growing problem for human health.”
Polyethylene makes up 30 percent of all synthetic plastic production, making it a large contributor to plastic waste pollution worldwide, according to the study. Today’s recycling system—which produces low-quality products—has only limited ability to serve as a long-term response to plastic pollution, the authors write.
In the environment, plastic breaks down in a years-long process known as oxidation, when oxygen penetrates the plastic molecules. Scientists have tried to speed this up, but that often “requires an aggressive pre-treatment” of the plastic, such as the application of heat or ultraviolet light, per the study. But the wax worm saliva enzymes were able to oxidize plastic in just a few hours—without any pre-treatment.