SPAIN – Researchers at the Center for Biological Research (CIB) in Spain have discovered that the saliva of wax worm species contains enzymes that are able to degrade plastics.

The researchers said two enzymes have been identified in the caterpillar saliva that can rapidly and at room temperature degrade polyethylene.

The study found that the Demetra enzyme had a “significant effect” on PE, leaving marks (small craters) on the surface of the plastic visible to the naked eye. Additionally, degradation products are formed after exposure of the PE to this enzyme.

Meanwhile, the Ceres enzyme oxidizes the polymer too but does not leave visible marks, suggesting that the two enzymes have a different effect on PE.

The researchers explain that PE is one of the toughest and most widely used plastics. Together with PP and polystyrene, it makes up 70% of total plastic production.

Plastic pollution threatens the planet’s health and environment, and biodegradation by microorganisms such as bacteria and fungi is proposed as a possible solution to tackle the plastic waste problem.

“This is changing the paradigm of plastic biodegradation,” said molecular biologist Federica Bertocchini of the Spanish National Research Council (CSIC), who led the study published in the journal Nature Communications.

Plastic is made of polymers designed to be hard to break down and contains additives that increase durability, meaning it can remain intact for years, decades or centuries.

“The very same features that make plastic the unique and useful material it is are creating one of the most critical problems of this century,” Bertocchini said.

“Plastics stay in the environment for a long time. It eventually breaks down into small particles, therefore becoming the source of micro and nano plastic particles.”

The study builds on the researchers’ 2017 findings that wax worms were capable of degrading polyethylene, though at that time it was unclear how these small insects did it.

The answer was enzymes — substances produced by living organisms that trigger biochemical reactions.

When asked how much time is required for the Demetra enzyme to degrade plastic, Bertocchini says that they don’t know that yet, but she highlights that they observe “a strong visual effect with Demetra after a few hours, and we know that increasing exposure increases the effect.”

Mechanisms by which these enzymes are able to degrade plastic are still unknown and more research combining insect biology with biotechnology is required.

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