Polystyrene, which is among the most common types of plastic used in many products such as packaging material, disposable cutlery, CD boxes, is not easy to recycle, and the vast majority of it piles up in landfills or in the oceans where it threatens marine life.
Scientists at Australia’s University of Queensland have discovered that superworms, which are Zophobas morio thrips larvae, are eager to eat this substance and that intestinal enzymes may be key to higher recycling rates.
Chris Rinke, leader of a study recently published in the journal Microbial Genomics, said earlier reports had shown that small wax and mealworms have a good track record of eating plastic, “so we hypothesized that much larger superworms might eat even more.” .
What is a super worm?
Superworms can reach sizes as large as five centimeters and are grown as a food source for reptiles and birds, and even for humans in countries like Thailand and Mexico.
Rinke and his team fed the superworms different diets for a period of three weeks, some of which were made of polystyrene foam, commonly known as styrofoam, and some of which were not fed at all. And here’s the result: “We confirmed that superworms can survive on a polystyrene diet alone and even gain a modest amount of weight compared to the fasting control group – suggesting that the worms can gain energy from eating polystyrene.”
Although the polystyrene-grown superworms completed their life cycles to pupate and then develop into fully adult insects, tests revealed a loss of microbial diversity in their guts and potential pathogens. These findings suggest that although insects can survive on polystyrene, it is not a nutritious diet and affects their health.
Next, the team used a technique called metagenomics to analyze microbial gut life and find out which gene-encoded enzymes are involved in breaking down plastic.
One way to use the findings would be to provide superworms with food waste or agricultural bioproducts to consume alongside polystyrene. “This could be a way to heal worms in a healthy way and to deal with a large amount of food waste, especially in Western countries,” says Rinke.
But while it is possible to grow more worms for this purpose, there is thought to be another way. Opening recycling facilities that mimic the eating processes of the larvae, which can be described as first breaking down the plastic in their mouths and then digesting it through bacterial enzymes.
“At the end of our [research], we want to take superworms out of the equation,” says Rinke, and now plans to organize further research aimed at finding the most efficient enzymes and then further improving them through enzyme engineering.
The degradation products from this reaction can then be fed to other microbes to form high-value compounds such as bioplastics, which he hopes will be an economically viable “upcycle” approach.
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