Moth larvae saliva studied as a response to plastic pollution • The Register

The caterpillar larvae of the wax moth produce saliva containing enzymes that can oxidize and break down polyethylene, offering a potential solution to the plastic pollution problem.

Plastics, made from synthetic molecules derived from fossil fuels, have transformed the industrial world since World War II. However, many plastics do not biodegrade naturally, leading to the accumulation of waste products on land and sea.

Polyethylene, or polyethylene, accounts for about 30 percent of synthetic plastic production. Although some studies show that it can biodegrade, this generally requires aggressive abiotic pre-treatment such as heat or irradiation. Degradation can be achieved by some microorganisms, but this can take months. At the same time, the scientists have not yet succeeded in identifying the responsible enzymes.

A group of scientists led by Federica Bertocchini, a postdoctoral fellow at the Consejo Superior de Investigaciones Cientificas (CSIC), the Spanish Research Council, has now identified the enzymes capable of degrading polyethylene in a few hours at room temperature.

The waxworm, larva of the wax moth, on a beeswax trellis (its main food source)

Waxworms are the caterpillar larvae of wax moths, also known as bee moths. They are nest parasites in bee colonies and eat bee cocoons, pollen and skins and chew through beeswax. But what is bad for bees can be good for humans.

Bertocchini and her colleagues studied the saliva of the waxworm (Galleria mellonella) and showed that it can break down polyethylene and said they identified two enzymes that can reproduce this effect.

In a paper published in Nature Communications, the authors suggest that these enzymes – which they named Demetra and Ceres after the Greek and Roman goddesses of agriculture – could offer new approaches to breaking down plastic waste and upcycling plastic components.

“The waxworm saliva can overcome the bottleneck step in the biodegradation of PE, namely the initial oxidation step. Within the saliva, we identify two enzymes belonging to the phenol oxidase family that can reproduce the same effect. To the best of our knowledge, these enzymes are the first animal enzymes with this ability, paving the way to potential solutions for the disposal of plastic waste through bio-recycling/up-cycling,” the paper reads.

It is estimated that there is about 8.3 billion tons of plastic in the world, of which about 6.3 billion tons is waste. Especially in oceans, plastic pollution endangers wildlife and enters the food chain.

“This study suggests that insect saliva may serve as a repository for degradative enzymes that could revolutionize the field of bioremediation,” the authors said. “Although further studies will be needed to gain a deeper understanding of the stepwise evolution of plastic in contact with salivary enzymes of waxworms, this discovery represents another potential approach to dealing with plastic degradation. This study is in the context of a circular economy opens a potential field in both plastic upcycling and the manufacture of the plastic of the future with ad hoc formulations that tend to facilitate degradation by selected enzymes.” ®