PLASTIC POLLUTION is a major problem all over the world. But the scourge of plastic pollution may soon be over. Spanish researchers have discovered chemicals in the saliva of wax worms that break down polyethylene (PE), a tough and durable material, in plastic.

The researchers say that one hour’s exposure to the saliva degrades the plastic as much as years of weathering. They’ve discovered two enzymes in the liquid that can degrade polyethylene at room temperatures and believe it’s the first time that such an effective agent has been found in nature.

Polyethylene plastic has a wide variety of uses. While efforts to reduce, recycle and reuse plastic are making progress, there are few options when it comes to the very sturdy polyethylene (PE) material.

It is one of the most widely used forms, comprising around 30% of production and is used for a wide range of materials including hard wearing items like pipes, flooring, and bottles but it’s also used for bags and food containers.

This plastic is dense and is very slow to break down in nature as it is highly resistant to oxygen. Most attempts to degrade it require PE to be pre-treated with heat or UV light to incorporate oxygen into the polymer.

The Spanish team first discovered that wax worms could break down the material in 2017, but in this study they found that the key elements are enzymes in the insect’s saliva. They showed that this key step of getting oxygen into the polymer can be achieved within an hour of the plastic being exposed to the saliva of the larvae.

They also found that the enzymes alone can oxidize plastic, which is the process that takes such a long time in the environment. The researchers are using saliva from the larvae of the greater wax moth, commonly known as wax worms. These insects are a well known pest that attacks and destroys honeybee hives.

The larva’s destructive abilities when it comes to beeswax may provide an explanation of their capacity for PE degradation. The scientists believe that what they’ve discovered so far provides a promising alternative approach to biological degradation and could lead to new solutions.

It is possible to apply this new understanding to large plastic waste management facilities. But it could also have a home-based kit, which could help degrade your own plastic.

There are still many questions to be answered including whether the saliva is working on the polymer or on the additives that are used to strengthen this type of plastic.

An area for exploration is to determine why the wax worm has these amazing enzymes and what’s the use of them in their daily life. They must now develop their work by carrying out bigger experiments. The field of biodegradation is focused on bacteria and fungi, mostly bacteria, and on looking for enzymes. This is certainly a good start with an enzyme that works. By Manny Palomar, PhD (EV Mail November 7-13, 2022)