A wax worm is seen eating a plastic bag. Photo by César Hernández/CSIC
April 24 (UPI) -- Scientists have discovered a caterpillar capable of biodegrading polyethylene, one of the toughest and most commonly used plastics.
The wax worm, the larval form of the greater wax moth, is already commercially bred as fishing bait. Now, scientists hope the caterpillar can be used to relieve the pressure on landfills already overflowing with plastic bags.
In the wild, the worm is a parasitic pest. Wax moths deposit their eggs inside bee hives. Once hatched, the worms subsist on beeswax.
Federica Bertocchini, an amateur beekeeper and researcher at the Institute of Biomedicine and Biotechnology of Cantabria, in Spain, noticed the worms had eaten holes in a plastic bag he was using to house the caterpillars after removing the pests from one of his hives.
In followup tests with biochemists from the University of Cambridge, roughly 100 worms consumed 92 milligrams of plastic mass in 12 hours -- a rate several times faster than that of a recently discovered strain of plastic-eating bacteria.
"If a single enzyme is responsible for this chemical process, its reproduction on a large scale using biotechnological methods should be achievable," Cambridge researcher Paolo Bombelli said in a news release. "This discovery could be an important tool for helping to get rid of the polyethylene plastic waste accumulated in landfill sites and oceans."
Though further investigation is required, researchers hypothesize that the caterpillar's wax and plastic biodegration mechanisms are the same -- the same chemical bonds are being severed.
"Wax is a polymer, a sort of 'natural plastic,' and has a chemical structure not dissimilar to polyethylene," Bertocchini said.
Researchers conducted tests to ensure the worms aren't simply breaking the plastics down into tinier pieces, but are transforming the chemical structure. Their analysis showed the caterpillars are turning the polyethylene into ethylene glycol, un-bonded 'monomer' molecules.
"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," said Bombelli.
Bertocchini, Bombelli and their colleagues detailed their work in the journal Current Biology.
The next step in their research is to figure out what kind of enzyme or enzymes the caterpillar is producing to break down the plastic. The answer could offer a solution to world's trash problem.