Yes, we all know that plastic is everywhere. One of the most widely used is polyethylene. It turns out to be a very difficult thing to degrade. How to reduce its impact? A small animal could help. The worm that disintegrates plastic. The wax worm.
Their larvae manage to decompose plastic in record time, barely an hour. The secret is in their saliva.
Its ability to break down plastic was discovered in 2017. But then researchers didn’t know how it did it. Federica Bertocchini, from the Center for Biological Research, tried to explain it.
They discovered that enzymes present in the worm’s saliva are capable of degrading it. “The polymer in contact with saliva oxidizes and depolymerizes within a few hours.” The results of the work are in BioRxiv.
“To degrade the plastic it is necessary for oxygen to penetrate the polymer. This first oxidation step usually takes a long time,” explains Bertocchini. “That’s why, under normal conditions, it takes months or years for plastic to degrade.” But the enzymes in the wax worm’s saliva perform this crucial step: they oxidize the plastic. “Therefore, they accelerate its decomposition,” he adds.
In addition, the team has analyzed saliva and observed a high protein content. These are two enzymes, named Demetra and Ceres. They belong to the family of phenol oxidase enzymes. The first “showed a significant effect on polyethylene. It leaves marks visible to the naked eye on its surface. The second also oxidizes the polymer, although without leaving visible marks.
Phenols are molecules that plants use as a defense against potential enemies. For example, insect larvae. In response, insects may produce phenol oxidase enzymes. They thus neutralize the effects and can feed on the plants safely. Phenols are also present in many plastic additives. Therefore, these enzymes can also attack them in that state.
It is not known how the plastic-disintegrating worm acquired the ability. It could be due to an evolutionary process. Whether this is so or not, the finding is remarkable. It would allow numerous applications in the treatment or recycling of plastic waste.