Packaging materials, disposable cutlery, CD cases: Polystyrene is among the most common forms of plastic, but recycling is not easy and most people end up in landfills or find their way to the oceans where it threatens marine life.
Researchers at Australia’s University of Queensland have now discovered that superworms – the larvae of Zophobas morio darkling beetles – are eager to eat on the drug, and their intestinal enzymes may be the key to higher recycling rates.
Chris Rinke, who led a study published in the journal Microbial genomics On Thursday, AFP reported that previous reports had shown that tiny wax worms and mealworms (which are also beetle larvae) had good results when it came to eating plastic, “so we assumed that the much larger superworms could eat even more.”
Superworms grow up to two inches (five centimeters) and are bred as a food source for reptiles and birds, or even for humans in countries such as Thailand and Mexico.
Rinke and his team fed superworms with different diets over a three week period, with some given polystyrene foam, commonly known as styrofoam, some bran and others not fed at all.
“We confirmed that superworms can survive on a diet of Styrofoam, and even gain a small amount of weight – compared to a hunger control group – suggesting that the worms can get energy from eating polystyrene,” he said.
Although the polystyrene-bred superworms completed their life cycle, became pupae and then fully developed adult beetles, tests showed loss of microbial diversity in the intestines and potential pathogens.
These findings suggested that although the insects may survive on polystyrene, it is not a nutritious diet and affects their health.
The team then used a technique called metagenomics to analyze the microbial gut community and find out which gene-encoded enzymes were involved in breaking down the plastic.
One way to use the findings would be to give superworms food waste or agricultural bioproducts to consume along with polystyrene.
“This could be a way to improve the health of the worms and to deal with the large amount of food waste in western countries,” said Rinke.
But while it is possible to breed more worms for this purpose, he envisions another way: to make recycling plants that mimic what the larvae do, which is to first tear up the plastic in the mouth and then digest it through bacterial enzymes.
“Ultimately, we want to take the superworms out of the equation,” he said, and he is now planning more research aimed at finding the most effective enzymes, and then improving them further through enzyme technology.
The degradation products from that reaction can then be fed to other microbes to make high-value compounds, such as bioplastics, in what he hopes would be an economically viable “upcycling” approach.
© Agence France-Presse