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Researchers discover ‘superworms’ capable of munching through plastic waste

The U.S. generates more than 45 million tons of plastic waste every year, and recycles less than 9% of that. A new discovery suggests these worms could help.

(CN) — What if the key to solving one of our thorniest environmental dilemmas was right under the ground we walk on?

In a startling discovery that could have major implications for landfills all over the world, researchers at the University of Queensland in Australia have found that a species of worm — the Zophobas morio — can, and indeed may even enjoy eating polystyrene, one of the most widely used form of plastics.

"Plastic waste is probably one of the biggest problems of our time," said Chris Rinke, a professor at the university's School of Chemistry and Molecular Biosciences, who led the team of researchers, in an email. "We are producing more plastic every year, but only a small fraction is recycled in most countries."

“Superworms," he aded, "are like mini recycling plants, shredding the polystyrene with their mouths and then feeding it to the bacteria in their gut.”

Rinke's team fed Zophobas, commonly known as "superworms," different diets over a three-week period. Some were given polystyrene foam, some were given bran, and some were given nothing. The ones eating plastics not only survived but thrived, gaining a marginal amount of weight, suggesting that microbes in the worms' guts help break down the polystyrene and turn it into energy.

Originally from central and South America, superworms, so named for their large size and high protein content, are common all over the world and are often used for reptile pet food (you can even buy oven-roasted chocolate-covered superworms for human consumption). While other research has suggested that superworms, as well as smaller worms, can eat and digest plastic, Rinke and his team's paper, published in Microbial Genomics, identifies for the first time several encoded enzymes within the superworm with the ability to degrade polystyrene and styrene. Rinke speculates that superworms may be able to digest other types of plastics.

"Other insect larvae have been shown to attack polyethylene plastic bags, so superworms might be able to do it as well," said Rinke in an email. "One of our next experiments will be to rear superworms on different types of plastic to answer this question."

Rather than unleash hordes of these super worms into the world, the scientists hope to grow the worms' gut bacteria in a lab, and further test its ability to degrade plastics.  

“We can then look into how we can upscale this process to a level required for an entire recycling plant,” said the paper's co-author, Jiarui Sun, a PhD candidate, in a written statement.

Plastic is among the most difficult material to recycle. Of the more than 45 million tons of plastic trash the U.S. generates every year, it recycles just 8.7 percent, according to data from 2018. If scientists can engineer enzymes that degrade plastic waste, it would be a revolution in the world of plastic recycling.

"Our long-term goal is a detailed characterization of the microbial enzymes in the superworm gut, and to engineer these enzymes for fast degradation of plastic waste in recycling plants through mechanical shredding, followed by enzymatic biodegradation," said Rinke in an email. "The chemical compounds resulting from this biodegradation can then be used to create new, more valuable products, such a bioplastic. This option to upcycle of plastic waste should incentivize plastic recycling and help to reduce the amounts of plastic debris disposed into the environment."

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