Wax Worm Saliva May Break Down Synthetic Material Helping With Plastic Waste Treatment, Recycling

A team of researchers at CSIC recently found that wax worm saliva degrades, a finding with several applications for recycling or treating plastic waste.

In 2017, the team found that this worm species, the lepidopteran Galleria Mellonella, can break down plastics also known as polyethylene, and now the same team has discovered just how it's doing this, a EurekAlert! report specified.

Specifically, the worm's saliva has enzymes referring to the phenoloxidase family that can quickly set off polyethylene degradation at room temperature.

According to CSIS researcher Federica Bertocchini from the CIB-CSIC, Center for Biological research who led the study, these enzymes are the first and only identified enzymes that are capable of degrading polyethylene plastic minus requiring pretreatment.

Wax Worm Saliva Oxidizes Plastics

Bertocchini explained that for plastic to degrade, there is a need for oxygen to penetrate the polymer, the plastic molecule.

This is the initial step in oxidation, which is typically an outcome of exposure to sunlight or high temperatures and depicts a bottleneck that's slowing down the degradation of plastics such as polyethylene, one of the most resistant polymers.

That is the reason, under normal environmental circumstances, plastic is taking months, or even years to degrade.

Now, the researcher also said, they have discovered that enzymes in the saliva of the wax worm are performing this important step, which is oxidizing the plastic.

Meaning, that they can overpower the bottleneck in the process of plastic degradation and rev its decomposition.

Degrading Polyethylene and Polystyrene

A couple of years back, a similar AMU Biochemical Society report said, a new field of study opened up with the finding that some insect species of the Lepidoptera and Coleoptera orders could degrade polyethylene and polystyrene.

Bertocchini explained that in their lab, they found the insect that appears to be the fastest of all, is the larvae of the lepidopteran Galleria mellonella, commonly called the wax worm.

The researcher added, that such larvae are able to oxidize and break down the polymers in the plastic absolutely fast, after only an hour of exposure.

In recent years, she added, initiatives have been made to determine how the said insects manage to do this. Several studies have focused on the microorganisms inhabiting the digestive system of the said worms, based on the assumption that they can use plastic as food and that their degradation would be the outcome of their metabolic activity, as well as their digestive processes.

This assumption though, continued Bertochhini, s highly questionable, and thus from the start, their study has focused on the oral activity of the worm species.

Wax Worm Behavior Observed

In their study, the study investigators scrutinized the behavior of the wax worm in terms of contact with polyethylene.

As a result, according to a related Eurasia Review report, they discovered that the enzymes present in the saliva of the worm, the liquid inside its mouth, can degrade polyethylene.

Essentially, she explained, on coming into contact with saliva, the polymer is oxidizing and depolymerizes within a few hours. The team has identified degraded residues that form in the presence of the wax worm saliva.

Moreover, the study authors have examined the saliva using electron microscopy. They were also able to observe a high-protein content.

To achieve such an observation, the team has isolated two enzymes from the saliva that can yield the oxidation produced by the saliva as a whole. The said two proteins known as Demetra and Ceres, belong o the family of enzymes called "phenoloxidase."

Related information about wax worms is shown on DW Planet A's YouTube video below:

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