Scientists identify a “supercharger” capable of eating plastic

The so-called “superhar” has its new superpower for science: consuming and breaking down plastic products such as polystyrene.

Zophobas died It is a species of dark larval beetle, native to a variety of North American habitats, from deserts to forests and all in between. According to a study published in June 2022, the insect has a special bacterial enzyme that is unique to the intestines and a unique hunger for polystyrene – a type of plastic commonly found in polystyrene and other plastic appliances.

Dark beetles survive in many habitats, including plastics. Because they are cheap and durable, plastics, which are made from organic polymers, can take decades to degrade. Polystyrene, a very common polystyrene, is one of the most widely produced plastics in the world and can last for decades in the environment. In 2018 alone, the latest available data, in this writing, plastic production reached 396 million tonnes (360 million tonnes), according to the European trade association Plastics Europe, and demand is expected to grow only while recycling rates remain low. That’s why scientists are exploring different ways to break down plastics.

The result is a superhero.

Over the course of several weeks, researchers at the University of Queensland in Brisbane, Australia, divided a total of 171 worms into three groups: one that ate only organic wheat balance, one that fed on a polystyrene diet, and a third group. he was not fed at all. Scientists tracked worms, their eating habits, and their weight.

The worms on each diet completed the life cycle and, surprisingly, among the worms that had only a plastic diet, more than 95% survived the research trajectory, a survival rate comparable to other groups.

“We found that the worms that fed the polystyrene diet not only survived, but also had low weight gain,” research author Chris Rinke said in a news release. “This suggests that worms can get energy from polystyrene, probably with the help of intestinal microbes.”

But how could an organic organism live on a pure plastic diet? To find out, the researchers performed a type of DNA analysis known as metagenomics. This field of study identifies the genomes of microorganisms, such as those that live in the intestines of supercars, to determine certain enzymes, which are proteins used to accelerate the chemical reaction of a cell.

In short, insects provide two physical and biochemical chops for breaking plastic. First, they use their mouths to cut the material into smaller pieces. Second, superworms ingest plastic particles that degrade the microbial community of the digestive tract more and more.

These plastic-degrading enzymes described in Microbial Genomics are also found in other species associated with polystyrene degradation. These species include a type of bacterium and human pathogen called Pseudomonas, which often causes pneumonia in foals, a disease known as Rhodococcus, and dozens of Corynebacterium, a bacterium that infects humans.

The ability to break plastic is seen in other species. For example, wax worms, known as Indian food moths, (Plodia interpunctella) are capable of degrading polyethylene as well Gallery mellonella, a honeycomb moth found all over the world. Meal worms are also able to survive on a polystyrene diet and have been shown to degrade plastic molecules in the digestive system, turning about half of the plastic into carbon dioxide and the other half into feces.

However, researchers in superworm research indicated that their findings raised many new questions: The findings opened a new can of worms, so to speak.

Chris Rinke / University of Queensland

“Which members of the microbial community are active, and which genes are transcribed a [polystyrene] diet compared to regular diet? What are the complete pathways of degradation of polystyrene and styrene used by intestinal microbes? Can some bacteria conserve energy by using non-polystyrene components? they wrote, adding that all of these questions may one day be areas of future study.

One goal, for example, would be to engineer intestinal enzymes into supercars at some point, to degrade plastic waste in large-scale recycling plants, a process known as enzymatic biodegradation. To that end, the research team predicts the growth of intestinal bacteria in the superworm study, leaving the worms aside, to test its ability to degrade polystyrene.

“Superworms are like low-recycling plants, they shred polystyrene with their mouths and then feed it to intestinal bacteria,” Rink said. “The breakdown products of this reaction can be used by other microbes to create high-value compounds such as bioplastics.”

The notion plays on the idea of ​​a circular waste economy that recycles materials instead of throwing them away. This “bio-recycling” of plastic waste can help reduce landfills and increase the degradation and recycling capacity of plastics.


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