Scientists Discover ‘Supervers’ Eat Plastic and May Help Tackle Pollution Crisis

The beetle larvae survived on a diet of only polystyrene due to enzymes in their guts, which could eventually be harnessed in plastic recycling bioreactors.

Image: The University of Queensland

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Plastic waste is so ubiquitous that particles have been detected in the air we breathethe food we eatand even our blood. Human consumption and disposal of plastic products has also polluted habitats across the planet, including almost every corner oceans, which is particularly pernicious because plastics can take centuries or even millennia to biodegrade.

As plastic pollution is expected to increase over the coming decades, it is imperative to develop sustainable recycling and upcycling processes for this waste, which includes polystyrene, a common material used to make polystyrene. Enter: the super verses.

Now, scientists have demonstrated that the larvae of the mealworm species Zophobas the dyingknown as “supervers”, can “survive on polystyrene foods” thanks to microbes in their guts, a finding that “will provide a basis for future investigations into microbial recycling of plastic waste”, according to a published study Thursday at Microbial genomics.

“Insect larvae actually have a good history of damaging and consuming plastics,” said Chris Rinke, senior lecturer at the Australian Center for Ecogenomics (ACE) at the University of Queensland and lead author of the paper. study, in an e-mail. “Initial studies, by other authors, reported that waxworms and common mealworms can eat plastic, so we thought that if these rather small larvae could do this, then the large superworms (up to 5.5cm) might be even better at chewing plastic.”

“It turned out that the supervers have a big appetite for polystyrene,” he added. “So we didn’t know if superverses could survive on plastic when we started our experiments, but we had high hopes.”

To reach this conclusion, Rinke and his colleagues divided 171 superworms into three groups with different diets: one ate only polystyrene, another ate bran, and a third was subjected to strict fasting. In a grisly twist, the team notes that instances of cannibalism among fasted superworms “led to our modified experimental design housing the starved control group animals in isolation, while animals from the other two groups were housed together for the duration of the experiment. ‘feeding trial’, according to the study.

In addition to observing the worms throughout the trial, the team also used gene sequencing to identify numerous genetic pathways associated with plastic-eating powers. As a result, the experiment provided “the first metagenomic analysis of a plastic-associated insect microbiome,” according to the study.

Super worms are hardy creatures and over 95% of each group survived their respective three-week diets. The bran-fed worms gained the most weight, but the larvae on the polystyrene diet also became slightly heavier and showed more activity compared to the starved worms, suggesting they may have gotten their nutrition from the waste. plastics, even if it came at a cost. to their health.

“The supervers raised on polystyrene gained only a small amount of weight and their gut microbiome diversity decreased, two signs that polystyrene is, as expected, a rather poor diet,” Rinke said. “We also found evidence of potential pathogenic bacteria, indicating that the polystyrene diet has negative effects on worm health. Supplying food waste or agricultural bioproducts with polystyrene could be one way to improve worm health.

While supervers may play a role in mitigating plastic waste, Rinke noted that the focus is on gut microbes in larvae, as their digestive secrets could be artificially mimicked and exploited on a large scale for use in bioreactors and other plastic processing facilities.

“We now have a catalog of all the bacterial enzymes encoded in the superver’s gut and plan to further investigate enzymes with polystyrene-degrading capabilities,” Rinke said. “We will characterize them in more detail over the next few years to find the most effective enzymes, which can then be further improved through enzyme engineering.”

“Ultimately, we want to eliminate superverses from the equation and mechanically shred plastic waste, followed by microbial degradation in bioreactors and subsequent microbial production of higher value compounds such as bioplastic,” said he concluded. “This recycling approach will make plastic recycling more economically feasible and should encourage plastic recycling.”

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