Now we can exploit the unique gut microbiome of tiny plastic-chewing worms to successfully break down problematic materials at scale.Zophobasatratus worms - more precisely, the larvae of the dusky beetle Carabid - are popular pet insect treats in many countries, where they are often raised and sold as food for reptiles. But while they're dubbed superworms for their protein-rich nutritional value, their real superpower may lie in the makeup of their gut bacteria.
In the new study, researchers at Nanyang Technological University in Singapore (NTUSingapore) built on previous studies of the microbiome of these hardy mealworms to build a scalable replica of the organism's specialized gut environment that they believe is capable of sustainably processing large amounts of common plastic.
While scientists have long known about worms' appetite for plastic, the question, as with many biotechnologies, was how to translate it into the real world. The team behind this "supergut" may have cracked the code. Very few worms are harmed in the process.
Associate Professor Cao Bin from Nanyang Technological University said: "A worm can only consume about a few milligrams of plastic in its lifetime, so you can imagine how many worms would be needed if we were to rely on them to dispose of plastic waste. Our method removes this need by taking the worms out of the equation. Our focus is on enhancing useful microorganisms in the worm gut and building an artificial 'worm gut' that can efficiently break down plastic."
The team first fed three groups of worms three different common plastics - high-density polyethylene (HDPE), polypropylene (PP) and polystyrene (PS), which are notoriously difficult to break down - for 30 days (a lucky control group was given oatmeal).
The scientists then extracted the microbiome from the guts of plastic-munching worms and cultured them in flasks filled with synthetic nutrients and three types of plastic, allowing them to develop into artificial guts over six weeks.
They found that the lab-grown worms produced more plastic-degrading bacteria in their guts than control worms, and that each bacteria showed greater efficiency in processing specific materials.
Dr. Liu Yinan, first author of the study, said: "Our study is the first successful attempt to cultivate a plastic-associated bacterial community from the gut microbiome of plastic-fed worms. By exposing the gut microbiome to specific conditions, we were able to increase the abundance of plastic-degrading bacteria in the artificial 'worm gut', indicating that our method is stable and can be replicated on a large scale."
While this is just a proof-of-concept, the researchers believe there are no barriers to growing such artificial "superguts" on a larger scale, and that such artificial "superguts" could be specialized to process specific materials. They are now studying the molecular biology behind the processes in the worm's tough gut, hoping to more easily engineer bacterial communities that break down plastic for commercial use.
The research was published in the journal Environment International.