A wax worm, a moth larva that eats wax made by bees to build honeycombs, is seen in a laboratory in this undated photo obtained by Reuters on October 1. 4. New research shows that two enzymes in the saliva of these worms easily break down polyethylene. (Simona Gaddi, via Reuters)
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WASHINGTON – Two substances in the saliva of waxworms, moth larvae that eat wax made by bees to build honeycombs, easily break down a common type of plastic, researchers said Tuesday, in a potential breakthrough in the global fight against coronavirus. plastic pollution.
The researchers said the two enzymes identified in the caterpillar’s saliva were found to rapidly and at room temperature degrade polyethylene, the world’s most widely used plastic and a major contributor to an environmental crisis stretching from ocean trenches to the tops of the mountains.
The study builds on the researchers’ 2017 findings that waxworms were capable of degrading polyethylene, though at the time it was unclear how these little bugs did it. The answer was enzymes, substances produced by living organisms that trigger biochemical reactions.
For plastic to degrade, oxygen must penetrate the polymer, or plastic molecule, in an important initial step called oxidation. The researchers found that the enzymes performed this step in a matter of hours without the need for prior treatment, such as the application of heat or radiation.
This is “changing the paradigm of plastic biodegradation,” said molecular biologist Federica Bertocchini of Spain’s Higher Council for Scientific Research, who led the study published in the journal Nature Communications.
Plastic is made from polymers designed to be difficult to break down and contains additives that increase durability, meaning it can remain intact for years, decades, or centuries.
“The very characteristics that make plastic unique and useful are creating one of the most critical problems of this century,” Bertocchini said.
“Plastics remain in the environment for a long time. Over time, they break down into small particles and thus become the source of plastic micro- and nanoparticles. These plastic particles have been found everywhere, from Antarctica to rain and tap water, which not only cause obvious environmental problems, but are a growing problem for human health,” added Bertocchini.
First created in 1933, polyethylene is inexpensive, durable, and does not interact with food, making it useful for food packaging and grocery bags, among other applications.
Wax worms are the larvae of wax moths, a species called Galleria mellonella. Considered pests by beekeepers, the caterpillars feed on beeswax, pollen, and honey, and occasionally eat bee larvae as well.
The idea would be to synthetically produce the enzymes from the worms’ saliva, which the researchers did, to break down plastic debris. Bertocchini said that using billions of waxworms to do the job has drawbacks, including the generation of carbon dioxide as they metabolize polyethylene.
The very characteristics that make plastic unique and useful are creating one of the most critical problems of this century.
–Federica Bertocchini, molecular biologist
“In our case, the enzymes oxidize the plastics, breaking them down into small molecules. This suggests alternative scenarios for dealing with plastic waste in which the plastics can degrade under controlled conditions, limiting or eventually completely eliminating the release of microplastics,” he said. the co-author of the study. author Clemente Fernández Arias, ecologist and mathematician from the CSIC.
A foundation related to the German engineering plastics company Röchling helped finance the research. Bertocchini is one of two leaders of a Madrid-based company called Plasticentropy that is working to commercialize the use of enzymes to break down plastic waste.
The search for the degradation of plastic by biological means, or biodegradation, previously focused mainly on microorganisms. A handful of microorganisms have been found to break down plastic, but they only slow it down and require pre-treatment, complicating the practicality of taking advantage of it.
Plastic consumption has skyrocketed around the world over the last three decades, with hundreds of millions of tons annually ending up as waste and less than 10% of that being recycled.
The United Nations in March approved a landmark deal to create the world’s first global treaty on plastic pollution after talks in Nairobi, with the goal of finalizing a legally binding deal by 2024.
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