Discover the “superver” that can digest plastic
Polystyrene is perhaps the most notorious of all the polymers we collectively call “plastics”. They are used in the packaging of peanuts and polystyrene containers, in bottles and disposal cutlery and jewelry boxes. In other words, polystyrene is absolutely everywhere – and, like so many other plastic products, lasts for millennia. Its inability to break down in the environment is one of the main reasons humans have lost control of plastic pollution and are looking for technology that could solve the problem.
Enter a species of mealworm larvae known as Zophobas morio. While the so-called “supervers” look like elongated, slippery orange caterpillars and are frequently used as food for pet reptiles, a new study in the scientific journal Microbial Genomics reveals that Zophobas morio has a bacterial enzyme in its gut that could put humans on the right track. In particular, the scientists found that “genera including Pseudomonas, Rhodococcus, and Corynebacterium that possess genes associated with polystyrene degradation.”
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The method behind the study was simple: researchers took various samples from Zophobas morio and raised them either on a bran diet, or on a polystyrene diet, or on a starvation diet. In doing so, they saw what kinds of enzymes were growing in the guts of superverses and discovered that many of them did indeed have the ability to degrade both styrenes and polystyrenes.
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At the same time, scientists noted that worms that survived on a strict polystyrene diet suffered from a loss of microbial diversity in their guts. This could outweigh the potential benefits of using this method to fight plastic pollution, if it makes the worms less healthy.
“Our results support previous suggestions that supervers can help reduce [polystyrene] waste,” the authors write. But, they noted, the worms did not derive many nutrients from a polystyrene diet. The “minimal weight gain” of the larvae is likely to “hinder their utilization in the [polystyrene] recycling process,” they continue. It may also mean that it might be difficult to use the worms’ natural abilities for biodiesel production, which can be done with ‘superworms raised on a regular diet’. Superworms (Zophobas morio), larvae (Getty Images/Mirek Kijewski)The authors added that one trick that could help is to diversify the diets of the worms to produce the necessary enzymes: specifically, by isolating microbes that degrade polystyrene and then engineering them on a large scale, they could “use the superver’s microbiome” to degrade polystyrene on a large scale.
In short, while their study demonstrated that these creepy-crawlies could help humans fight plastic pollution, it also raises many other challenges.
Plastic pollution is one of the main threats to the future of the Earth, clogging the oceans and terrestrial nature in equal measure. Among the many problems caused by plastic pollution, plastics are also linked to infertility. Declining sperm count has already been attributed, at least in part, to chemicals found in many types of plastic products, and experts fear humanity is facing a mass infertility crisis.
“Chemicals in plastic (phthalates, bisphenols and others) along with pesticides, lead and other environmental exposures are linked to impaired reproduction, including sperm count and quality,” Dr. Shanna Swan, professor of environmental medicine and public health at Mount Sinai School. of medicine in New York, Salon said in March. “Some, like phthalates and BPA, have a short half-life in the body (4-6 hours), so it’s possible to reduce body exposure if we can stop using products that contain them. “
Superverses aren’t the first organism to be seen as a possible savior in the plastic crisis. In April, scientists published an article about efforts to create bacteria that produce plastic-dissolving enzymes. They specifically discovered that there is an enzyme that targets polyethylene terephthalate after finding bacteria “eating” bottles outside a factory in Osaka, Japan.
“The new species, Ideonella sakaiensis, breaks down plastic using two enzymes to hydrolyze PET and a primary reaction intermediate, ultimately producing building blocks for growth,” the scientists explained. They added that “plastic pollution represents a global environmental crisis. In response, the microbes develop the ability to use synthetic polymers as carbon and energy sources.”
For more articles from the Salon on plastic pollution: