Superworms: how plastic-eating larvae sparked a scientific breakthrough

15 Nov 2022
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Superworms have an appetite for polystyrene and could be the key to plastic recycling on a mass scale.


Microbiologist Dr Christian Rinke is in his office at The University of Queensland answering an email from a high school biology teacher in New York City.

Brittany Beck and her class got in touch after seeing a New York Times article about his team’s groundbreaking study that found common ‘superworms’ can digest polystyrene.

The teenagers have been conducting their own classroom experiments, but with mealworms, and excitedly asked Dr Rinke to consider helping them submit their findings to a scientific journal.

It’s a full circle moment for the Austrian native.

In Graz, southwest of Vienna, Dr Rinke's own high school biology teacher, Mrs Berger, first sparked his interest in science that has led to research into some of the tiniest living things on the planet.

“Microbes are really important players in the ecosystem,” Dr Rinke said.

“If you go back into earth history it was cyanobacteria that started to produce oxygen, and changed the whole climate.”

Dr Christian Rinke

Dr Christian Rinke

Dr Rinke said microscopic organisms often don’t get the credit they’re due for looking after the planet.

“Yes, we should protect the rainforests but if you see who does the most carbon fixation, it's actually the microbes in the ocean,” he said.

“Without them, our climate would be quite different.

“I would argue the planet is mostly run by microbes, because they produce oxygen, consume and release greenhouse gases and recycle organic matter.”

They could also hold the key to a huge environmental conundrum – what we do with our plastic waste.

Enter the Zophobas morio "superworm".

Several dozen of these worms – technically the larvae of the darkling beetle – are munching away on chunks of polystyrene inside a clear storage box in Dr Rinke’s lab on the fifth floor of the Molecular Biosciences building at UQ’s St Lucia campus.

With the lid off, the communal chewing sounds like the moment milk is poured onto a bowl of Rice Bubbles, or when popping candy lands on the tongue.

Superworms are not only eating and digesting polystyrene, they are also gaining weight from it.

Superworms are not only eating and digesting polystyrene, they are also gaining weight from it.

These aren’t the worms used in the experiment, but were brought in "fresh" to demonstrate the process at the time of the paper’s publication.

The media interest has been intense, and the worms have been a hit.

TV and radio microphones have been lowered to capture audio of the mastication and a GIF of the hungry wrigglers has been re-tweeted countless times.

The study's findings have been reported in scientific publications and major news outlets across the globe.

Dr Rinke is surprised and delighted with the response, after first proposing the study in a project pitch competition among colleagues at UQ’s Australian Centre for Ecogenomics.

“I had read a previous scientific paper about the waxworm insect larvae, that could eat plastic bags,” he said.

“Another study looked at the regular mealworm, but they’re only small.

“My idea was to try it with a larger species, the superworm – which is commonly used as pet food here in Queensland - that could eat way more plastic.”
Dr Christian Rinke

Dr Rinke’s pitch was voted the winner and secured some modest funding.

He and PhD candidate Jiarui Sun found that superworms that were fed just polystyrene for three weeks not only survived but put on weight, suggesting they can derive energy from a purely plastic diet.

“We used metagenomics to find several encoded enzymes in their gut with the ability to degrade the plastic,” Dr Rinke said.

It’s hoped those enzymes can be engineered so plastic waste can be broken down on a mass scale in recycling plants, reducing landfill.

The experiment was partly inspired by Dr Rinke’s unconventional journey to Australia.

He and wife Alena, also a microbiologist, sailed into Bundaberg aboard their 34-foot yacht Green Panther in November 2014.

The trip had begun on the west coast of the United States, where Dr Rinke worked at the Department of Energy's Joint Genome Institute in San Francisco.

The newlyweds gave away their home contents and packed up for life at sea and the vague promise of a job for Dr Rinke in Brisbane.

After crossing the Pacific, they spent a week anchored off a tiny island on the atoll of Raroia in French Polynesia, snorkelling and swimming in crystal clear water.

“We decided to thank the island for hosting us with a beach clean-up,” Dr Rinke said.

Dr Rinke with his wife during their trip across the Pacific.

Dr Rinke with his wife Alena during their trip across the Pacific.

The pair rowed their dinghy ashore with two large garbage bags, which were quickly filled with plastic bottles, styrofoam, nylon fishing line and random shoes.

“I was just sad to see so much garbage had made it onto the shores of a tiny uninhabited island in the middle of the ocean.”

The experience stayed with Dr Rinke and helped inspire his current work.

“I’m waiting to find out if I’ve secured more funding to further research the superworm’s gut enzymes,” he said.

“The potential of this project could take five-plus years to become viable, but I’d love to see it through.”

Dr Rinke says the scientific support for his project has been gratifying, but capturing the interest of the general public could be the key to driving it forward.

He’s already achieved that goal with Ms Beck and her class in New York.

After watching a video presentation of mealworms in action in a Brooklyn classroom, Dr Rinke tells the students he’s happy to help get their experiments published.

In the lab down the hallway, glistening superworms wriggle in their box and continue digesting their plastic dinner.


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