Researchers are currently investigating the potential of using worms to help combat the excessive plastic pollution around the world, thanks to a chance discovery by scientist and amateur beekeeper Federica Bertocchini.
After picking parasitic wax worms off the honeycombs of her beehives, Bertocchini placed them in a plastic bag – and when she returned, she found that the worms had munched holes through the plastic and escaped. Inspired, Bertocchini began collaborating with scientists at England’s University of Cambridge to study the worm’s potential for addressing plastic pollution.
Commercially bred for use as fishing bait, the wax worm has the unique power to biodegrade polyethylene, the plastic used for shopping bags, at an incredible speed. The study proved that these worms can biodegrade plastic at an extremely accelerated rate even when compared to other plastic eaters, like the plastic-eating bacteria discovered in early 2016.
In fact, researchers found that after placing 100 wax worms in a plastic shopping bag, holes began forming after only 40 minutes. And 12 hours later, the amount of plastic was reduced by 92mg. Plastic-eating bacteria consume polyethylene at a rate of 0.13 mg per day, and when plastic is left in a landfill, it can take 100 to 400 years to degrade.
“Wax is a polymer, a sort of natural plastic, and has a chemical structure not dissimilar to polyethylene,” said Bertocchini, from the Spanish National Research Council. “The caterpillars are not just eating the plastic without modifying its chemical make-up. We showed that the polymer chains in polyethylene plastic are actually broken by the wax worms.”
These worms frequently live as parasites in bee colonies, wreaking havoc on the hives by eating through the wax comb. According to researchers, breaking down beeswax would require similar kinds of chemical bonds as would be used to degrade plastic.
An analysis of the biodegradation process showed that the worms can transform the polyethylene into ethylene glycol, which is a chemical that is primarily used in the creation of anti-freeze and polyester. The team also learned that similar degradation results can be achieved by crushing the worms and smearing them into polyethylene.
“The caterpillar produces something that breaks the chemical bond, perhaps in its salivary glands or a symbiotic bacteria in its gut,” said Paola Bombelli with Cambridge University. “If a single enzyme is responsible for this chemical process, its reproduction on a large scale using biotechnological materials should be achievable.”
With people throughout the globe using approximately one trillion plastic bags each year, and an annual global production of more than 45 million tonnes of polyethylene, much of this plastic winds up in landfills – where it biodegrades at an incredibly slow rate. However, with this new discovery, there could be a biotechnical approach to combating plastic pollution in the near future – especially when combined with the power of Styrofoam-eating mealworms.
“The next steps for us will be to try and identify the molecular processes in this reaction and see if we can isolate the enzyme responsible,” Bertocchini said.