Scientists have discovered that a caterpillar species that is bred for fishing bait has the ability to biodegrade polyethylene, meaning the critter can eat and process plastic shopping bags.
In the wild the species, called wax worms, live as parasites in bee colonies. A scientist and amateur beekeeper, Federica Bertocchini, was removing the worms from her hives and put them in plastic shopping bags. She then found the bags were riddled with holes.
That led to colleagues at the University of Cambridge's Department of Biochemistry to conduct a timed experiment. About 100 wax worms were exposed to a plastic bag from a U.K. supermarket. After just 40 minutes, holes appeared in the bag. After 12 hours the plastic mass of the bag had reduced by 92mg.
"This discovery could be an important tool for helping to get rid of the polyethylene plastic waste accumulated in landfill sites and oceans."
Polyethylene is largely used in packaging, and accounts for 40% of total demand for plastic products across Europe - where up to 38% of plastic is discarded in landfills. People around the world use around a trillion plastic bags every single year.
Generally speaking, plastic is highly resistant to breaking down, and even when it does the smaller pieces choke up ecosystems without degrading. The environmental toll is a heavy one.
Yet nature may provide an answer. The beeswax on which wax worms grow is composed of a highly diverse mixture of lipid compounds: building block molecules of living cells, including fats, oils and some hormones.
While the molecular detail of wax biodegradation requires further investigation, the researchers say it is likely that digesting beeswax and polyethylene involves breaking similar types of chemical bonds.
"Wax is a polymer, a sort of 'natural plastic,' and has a chemical structure not dissimilar to polyethylene," said CSIC's Bertocchini, the study's lead author.
The researchers conducted spectroscopic analysis to show the chemical bonds in the plastic were breaking. The analysis showed the worms transformed the polyethylene into ethylene glycol, representing un-bonded 'monomer' molecules.