Plastic Eating Worms Show Promise for Plant-Scale Recycling

The Zophobas morio ‘superworm’ can eat through polystyrene. Image supplied by University of Queensland

Researchers at the University of Queensland have found that a common species of worm with a taste for polystyrene may significantly contribute to plastic recycling.

The team, led by Dr Chris Rinke from UQ’s School of Chemistry and Molecular Biosciences, found that the Zophobas morio—known as ’superworm'—enjoys munching on polystyrene and can metabolise it due to a particular bacterial enzyme in its gut.

Superworms are the larvae of the Zophobas morio beetle, native to Central and tropical parts of South America, and grow up to 60 millimetres (2.5 inches) in length.

The worms were fed diets of either polystyrene foam, wheat bran or put on fasting diets over a three-week period.

“We found the superworms fed a diet of just polystyrene not only survived but even had marginal weight gains,” Rinke said.

“This suggests the worms can derive energy from the polystyrene, most likely with the help of their gut microbes.”

The team found the worms contained several encoded enzymes capable of degrading polystyrene and styrene, so their goal now is to engineer such enzymes to degrade plastic waste in recycling plants via mechanical shedding and subsequent enzymatic biodegradation.

Rinke said the superworms are mini recycling plants that shred the polystyrene with their mouths and then feed it to their gut bacteria.

“The breakdown products from this reaction can then be used by other microbes to create high-value compounds such as bioplastics.”

Dr Chris Rinke from the University of Queensland's School of Chemistry and Molecular Biosciences. Image supplied by University of Queensland

Researchers hope that this form of bio-upcycling will be utilised in plastic waste recycling to reduce landfill around the world.

Co-author of the research, PhD candidate Jiarui Sun, said the plan is to grow the gut bacteria in a lab and further test its ability to degrade polystyrene.

“We can then look into how we can upscale this process to a level required for an entire recycling plant,” he said.

Rinke told the Epoch Times that on a recycling plant scale, the polystyrene would be shredded and then immersed in an enzyme cocktail like a large bioreactor, but the ideal conditions for the enzymes to survive still need to be determined.

‘That’s one of the big bottlenecks. We have an idea what the enzymes are, but they are not very well characterised,” he said.

“That’s something we want to do over the next year to actually express those enzymes in our laboratory in larger quantities and characterise them in great detail, so we know exactly what’s the right temperature, what’s the right pH.

“So that’s a lot of research needs to be done,” Rinke said.