From food to plastic, a bacterium will save us
by Andrea Barchiesi
They call it “superworm” because it is similar to the flour maggot (the miller darkness), but exceeds it in tonnage. And it has been proposed, in several nutritional studies, as an alternative food, both for farms and for the human diet due to the high content of proteins and fats. But for some time he has also been known for his “superpower”: eat plastic. To be precise, it appears to be greedy for polystyrene. A group of Filipino high school students first noticed this a few years ago. Since then, the ability of the larvae to Zophobas morio, its scientific name, of eating polystyrene, has become a subject of study. New research from the Australian University of Queensland reveals how plastic disposal plants could be built by exploiting these capabilities.
by Andrea Barchiesi
Chris Rinke and researchers from the Australian University’s School of Chemistry and Molecular Biosciences have put this talent to the test. The larvae of Zophobas morio they grow up by eating a variety of things, but mostly wheat bran and other grains. Their life cycle, like all larvae, foresees that at some point they form a cocoon, become pupae, and reappear as an adult individual. In their case, a black beetle. This happens if they remain isolated. But if kept in large groups, they remain larvae and continue to eat.
Rinke and colleagues then fed one group of larvae with bran for three weeks, another group with Styrofoam alone, and left another to fast. According to the results, presented in a paper published in the journal Microbial Genomics“the superworms who ate styrofoam not only survived, but also gained some weight – says the team coordinator – this means that the worms can obtaining energy from polystyrenemore likely with the help of the microbes inside them. “
And here’s where we go to investigate. “The researchers used a technique called metagenomics to find different enzymes encoded with the ability to degrade polystyrene and styrene “, reads the press release of the study. Although polystyrene, according to recent studies, appears to degrade in” just “a hundred years in sunlight, they they can do the same in few days. And if the “superworms” are, in Rinke’s words, like “small recycling plants, which shred the polystyrene with their mouths and then feed it to the bacteria in their bellies”, you have to create something similar, but bigger.
Instead of filling giant tanks with millions of superworms that open their jaws waiting for a cascade of white polystyrene (a fascinating but impractical idea), one thinks rather of imitate their functioning. Chopping the material and then feeding it to the replicated enzymes thanks to the study of Zophobas morio. Then grow gut bacteria in the lab and further test their abilities to degrade polystyrene and “raise this process to a level required for an entire recycling plant,” he said. Jiarui Sun, PhD student and second signature of the study. And what remains at the bottom of this process? According to Rinke “the degradation products of this reaction can be used by other microbes to create high-value compounds such as bioplastics”.
Zophobas morio it is just one of the invertebrates that promise to help us, if not to solve, at least to mitigate the problem of the billions of tons of plastic that are produced every year and are dispersed in the environment all over the world. Even the Tenebrio Molitor, for example, it has these capabilities. In 2017 an Italian biologist (and beekeeper) Federica Bertocchini, from the Spanish Institute of Biomedicine and Biotechnology of Cantabria, discovered the caterpillar that eats plastic, in this case polyethylene. It is the larva of the Galleria mellonella, called wax moth. While all over the world, research institutes and companies are studying enzymes obtained from insects and microorganisms found in compost and landfills, which have the “superpower” to degrade plastic.
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