A worm that eats and digests styrofoam
Hundreds of millions of tons of plastic are produced worldwide every year; according to estimates, only about one tenth of this is recycled. The mechanical and chemical processes are very costly, in some cases quite energy-intensive and sometimes harmful to the environment. For years, therefore, the search has been on for alternative biological methods that can be used to break down and, in the best case, recycle the mountains of waste that are produced.
As early as 2016, a Japanese team reported on a bacterium that can degrade polyethylene terephthalate (PET) with the help of two enzymes. Since then, enzymes that can break down various plastics have been identified again and again, including in the body of a caterpillar that eats plastic bags or in cow stomachs. Work is now underway to make the naturally occurring enzymes even more efficient, because degradation is still usually quite slow.
Australian researchers have now discovered another candidate for such a biodegradation process: a worm with an appetite for polystyrene, which is known primarily in its expanded form under the brand name Styropor. Dubbed the “superworm,” Zophobas morio is actually a large black beetle in the larval stage.
The team, led by Chris Rinke of the University of Queensland, fed the animals Styrofoam for three weeks. A comparison group was given bran, and another was put on a diet. “We found that the Styrofoam-fed worms not only survived, they had actually gained some weight,” Rinke said in a release about the study, which has now appeared in the journal Microbial Genomics. This shows that the worms can even obtain energy from the polystyrene.
Using metagenomic methods, the team identified the enzymes with which the worms’ intestinal bacteria were able to utilize the plastic. They are now continuing to work with this in the laboratory, with the aim of one day being able to apply the degradation process on a large scale. “The superworms are like little recycling plants; first the Styrofoam is broken down with their mouths and then fed to the gut bacteria,” Rinke said. In a recycling plant, the process would be quite similar: First would come the mechanical shredding, then the degradation with the help of enzymes. The degradation products could then be used to make bioplastics.