Scientists have discovered that a commercially bred caterpillar for fishing bait has the ability to biodegrade polyethylene – one of the most difficult and most widely used plastics in our society. The larvae of the waxworm ( Galleria mellonella ) live in nature as parasites in bee colonies as the moths lay their eggs inside the hives where the worms hatch and grow in the beeswax (hence their name).
The discovery has been entirely accidental. One of the scientists, Federica Bertocchini, an amateur beekeeper, was removing parasitic pests from the combs of her hives. He temporarily placed the worms in a typical plastic bag and it was riddled with holes in a matter of hours.
Bertocchini, from the Institute of Biomedicine and Biotechnology of Cantabria (CSIC), collaborated with experts Paolo Bombelli and Christopher Howe from the Department of Biochemistry at the University of Cambridge (United Kingdom) to carry out a timed experiment. Around 100 waxworms were exposed to a plastic bag from a UK supermarket. Holes then began to appear after just 40 minutes, and after 12 hours the plastic mass had reduced by 92 mg.
Scientists say that the rate of degradation is extremely fast compared to other recent discoveries , so these caterpillars can represent an important advance in the management of plastic waste and in the conservation of the natural environment.
The most surprising thing is that they not only degraded the plastic, but the worms chemically transformed the polyethylene into ethylene glycol, a thick and liquid chemical compound , a function annexed to that carried out in the hives, their natural habitat. “Wax is a polymer, a kind of natural plastic, and it has a chemical structure not very different from polyethylene,” explains Bertocchini.
The conclusion of this work is that once the molecular details of the entire process have been studied, these wax worm larvae could be used to design a biotechnological solution that helps manage the waste generated by plastic.
About polyethylene
Polyethylene is used mainly in packaging (for food products and in bags) and represents 40% of the total demand for plastic products throughout Europe, where up to 38% of plastic ends up in landfills. Around the world we use about a trillion plastic bags each year.
Plastic is very resistant to breakage and the consequences on the environment are significant. However, nature seems to have provided us with an answer.
“The caterpillars are not only eating the plastic without modifying its chemical composition, but the polymer chains in polyethylene plastic are actually broken by the wax worms,” said Paolo Bombelli, co-author of the work.
“The caterpillar produces something that breaks the chemical bond, perhaps in its salivary glands or a symbiotic bacteria in its gut. The next steps for us will be to try to identify the molecular processes in this reaction and see if we can isolate the responsible enzyme.” judgment.
The study has been published in the journal Current Biology.
Credit Image: César Hernández / CSIC
