Waxworm saliva appears to degrade plastic bags in just hours

The search for new solutions to the growing problem of plastic pollution has led scientists to some interesting places, including the grounds of a Japanese recycling center and the guts of superworms. These efforts have discovered enzymes that can devour plastic materials with high efficiency, and scientists in Spain have just discovered more in the saliva of wax worms, which have the ability to degrade plastic bags in hours at room temperature.

The discovery of these enzymes comes from the work of Federica Bertocchini, a biology researcher and beekeeper in Spain, who stumbled upon a strange ability of wax worms in 2017. These parasites feed on beeswax and, in an attempt to protect her hives since the disaster, Bertocchini placed plastic bags over them as protection.

Within 40 minutes, the bags were full of holes. Plastic bags are made of polyethylene, which accounts for about 29 percent of global plastic consumption and is known to be difficult to break down. That it took the worms about 12 hours to turn the material into a mess presented some interesting possibilities, with the experiments showing that the worms were actually digesting the plastic, rather than just chewing it.

However, questions remained as to exactly how this process took place, with scientists trying to identify the mechanisms behind the worms’ ability to ingest the plastic. That brings us to new research published this week, led by Bertocchini and her team at the Center for Biological Research in Madrid.

The scientists used an electron microscope to analyze the waxworms’ saliva and traced their appetite for plastic to a pair of enzymes. Within hours at room temperature, these enzymes worked together to create visible craters on the surface of the plastic and simultaneously oxidize the material. Working in tandem in this way, the team sees the pair of enzymes as a new weapon against plastic degradation, and one that has clear strengths over other enzymes with similar abilities.

“For plastic to degrade, oxygen must penetrate the polymer (the plastic molecule),” explained Bertocchini. “This is the first step in oxidation, which is usually the result of exposure to sunlight or high temperatures, and represents a bottleneck that slows the degradation of plastics such as polyethylene, one of the most durable polymers. Therefore, under normal environmental conditions, plastic takes months or even years to degrade. These enzymes now discovered are the first and only known enzymes capable of degrading polyethylene plastic by oxidizing and breaking down the polymer very quickly (after only a few hours of exposure) without the need for pretreatment and working at room temperature.”

The scientists hope to carry out further work uncovering the mechanisms behind the enzymes’ ability to degrade plastics. They note that there is much more work to be done, but hope that the technology can one day help tackle the growing problem of plastic pollution.

You can hear Bertocchini (in Spanish) in the video below, while the research was published in the journal Nature communications.

Source: Center for Biological Research in Madrid