Wax Worm Saliva Is the Unlikely Hero of Fighting Plastic Waste

Their enzymes can break down plastic in a matter of hours

hand holds plastic with holes and wax worm
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.

Because plastic is made to be durable, it’s notorious for remaining intact, polluting ecosystems, seafood, water and even humans’ bloodstreams.

“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.

Andy Pickford, the director of the Centre for Enzyme Innovation at the United Kingdom’s University of Portsmouth who was not involved in the study, tells the Guardian that the new finding is thrilling. Because wax worms degrade plastic so quickly and without the need for extreme temperature conditions, “enzymatic breakdown may be a route to making use of polyethylene waste,” he tells the publication.

The finding could also be applied to large plastic waste management plants as well as contribute to the development of at-home kits that allow people to recycle their own plastic waste, Bertocchini tells BBC News Matt McGrath.

Still, using wax worms to recycle plastic at scale has some drawbacks. For one, billions of plastic-metabolizing insects would release carbon dioxide, per Reuters.

Study co-author Clemente Fernandez Arias, an ecologist and mathematician at the Spanish National Research Council, tells the Guardian that more research needs to be done to develop the discovery into a tangible way to combat plastic pollution.

But in the future, the research “suggests alternative scenarios to deal with plastic waste in which plastics can be degraded in controlled conditions, limiting or eventually eliminating altogether the release of microplastics,” Fernandez Arias tells Reuters.

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