A snacking superworm that loves to eat polystyrene may hold the key to helping recycle plastic waste with a bacterial enzyme in its gut, researchers say.
University of Queensland researcher Chris Rinke said previous studies found the superworm, or common Zophobas moria, could eat polystyrene, but his research was taking a different approach.
"Superworms are like mini recycling plants – shredding the polystyrene with their mouths and then feeding it to the bacteria in their gut," Dr Rinke said.
"Usually researchers would … pick out a few microbes and analyse them further, [but] they're really looking for the needle in the haystack."
Bur Dr Rinke said he was taking a different tack, using a method called metagenomics, which extracted and sequenced all the DNA from the microbes.
"Then we can basically make a catalogue of all the genes that are there, all the enzymes that are there," he said.
"We definitely have to collect and characterise them even further so we know what exactly what they're doing, and what conditions they work better, like what temperature."
Enzyme engineering
Dr Rinke said the next step for researchers would be studying those enzymes in the lab in greater quantities, which was "probably going to take a few years".
Dr Finke said it was hoped scientists would be able to develop a kind of "synthetic superworm".
"What we are really after is to kind of mimic the superworm — basically have mechanical shredding that the worm does, and then have like bioreactors where we add the enzymes from the microbes and then degrade that on like a big, big scale," he said.
"That's why I'm excited about a project like this, because then at least as we find possible solutions, we can push those further and make them actually work in the real world," he said.
Dr Rinke said not all of the polystyrene was broken down in the superworm's gut, coming out as "probably half-degraded polystyrene" in its faeces.
"It's [faeces] definitely not something I would want to release in the environment," he said.
"After like 48 hours or so you can see that their faeces is actually changed to becoming from brown bran to like white polystyrene.
"The good thing about superworms is they they're not picky eaters, so you can definitely see superworms eating the faeces of other superworms and then maybe they go for a second round [that breaks down that polystyrene]."
He said though scientists want to add food waste for a more nutritious diet for the worms, because although they can live on polystyrene, "they're not doing super great".
'The big guys'
Similar studies have used mealworms, which are about 2.5 centimetres long, but superworms are "way larger" at about 5 centimetres long.
"Based on that, [superworms] can eat way more polystyrene and I would argue that makes them way more effective — they're the big guys," he said.
He said superworms were the insect larvae of a darkling beetle.
"The common name is superworm — but technically they're not actually worms, which wouldn't have any legs — they are actually insects," he said.
"In a nutshell, the beetle lays eggs and after a week you have the larvae and they are called superworms.
"They are really eating machines and they eat their whole life — it's about at least like five, six months.
"Then if they're big enough, they actually turn into a pupa and then they have metamorphoses like similar to a butterfly and turn into [adult beetles]."
He said there was reports the insect could live as a larvae for more than six months, but was not sure yet for how long.
"But the funny thing is, if you actually give them food and keep them in big numbers close together, as long as they touch each other a lot, they just keep going and so they wouldn't even become a pupa, become a beetle — they just love it so much.
He said the insect was originally from the tropics, like Central and South America.
"I would envision that they actually stick more likely to warmer climates, so you wouldn't see them when it gets too cold," he said.
'Open-roasted, chocolate-covered' superworms
Dr Rinke said some people that use live mealworms as pet food kept them in the fridge, so they developed slower.
"But superworms don't do that as they will die because they need a certain temperature that restricts probably where they are," he said.
He said superworms were also a pet food and in some countries they were actually used for human consumption.
"You could actually in some countries order open-roasted, chocolate-covered superworms if you want," he said.
"They have a very high nutritional value — high protein and also high in fat content so, they're a good snack if you go hiking."
