Scientists have identified a humble caterpillar that could hold the key to tackling global plastic pollution. Every year, we produce nearly 300 million tons of plastic that ends up polluting every part of the world. Plastic does not degrade easily, and it is dangerous for a range of animals, including marine creatures. The newly identified waxworms can break down the chemical bonds in the most commonly used plastic at incredibly high speeds.
The waxworms degrade plastic and beeswax the same way
Researchers in the UK and Spain found that the larvae of the wax moth Galleria mellonella, which live on wax in bee hives, can also degrade polyethylene, the most commonly used plastic. The waxworms break down the chemical bonds of plastic the same way they digest beeswax. Wax moths lay eggs in bee hives, where the worms live as parasites and grow on beeswax.
Scientists led by Federica Bertocchini of the University of Cantabria in Spain found that the waxworms could chew a significant hole in a plastic shopping bag in less than 40 minutes. The accidental discovery occurred when Bertocchini cleaned out the bee hives in her backyard a couple of years ago. She took some waxworms from the hive and placed them in a used plastic bag.
When Federica Bertocchini checked the plastic bag about an hour later, she noticed that it was riddled with holes in part of the bag with larvae. They are called waxworms because they live on wax in bee hives. Wax, just like plastic, contains long strings of carbon atoms. Wax and polyethylene both have a similar carbon structure. Dr. Paolo Bombelli of the University of Cambridge, one of the researchers, said the caterpillar was just the starting point.
Researchers trying to identify the enzyme that degrades plastic
During the study, researchers placed worms on the plastic and calculated the time it took them to chew a hole. Bertocchini found that each worm was able to create 2.2 holes per hour. A group of 100 waxworms degraded 92 milligrams of plastic overnight. At the same speed, it would take the same group about a month to fully degrade an average, 5.5g plastic bag.
To figure out whether it was the munching action that was breaking down the plastic or something else, scientists applied a soupy blend of recently dead waxworms on a piece of plastic. Surprisingly, the liquid worms were also able to create holes in the plastic. It led researchers to conclude that an enzyme produced by the worms or bacteria living in their bodies was degrading the plastic bag.
The unidentified enzyme breaks down polyethylene into ethylene glycol. Scientists plan to conduct further studies to understand the details under which the process takes place, and identify the enzyme. If the enzyme could be produced on a large scale, it would help minimize the problem of plastic waste. Dr Bertocchini said she and her colleagues were working towards saving our environment and oceans from the consequences of plastic accumulation.
Findings of the study were published in the journal Current Biology.
Other potential solutions
The scientific community has been looking for ways to biologically degrade plastic for decades. But most of the methods take way too much time to degrade plastic materials. The newly identified waxworms are among the fastest. Every year, thousands of creatures die because of plastic trash that we dump almost everywhere.
In 2014, scientists at Stanford University discovered a gut bacterium in a different species of wax worm. It was also able to degrade polyethylene, the most commonly used plastic, but it yielded different byproducts, says the National Geographic. Scientists believe that there could be many other worm species capable of breaking down plastic. While scientists are working to find solutions to the plastic pollution, one of the best ways to save the environment is to minimize plastic use and recycle more.