Into the Wormhole: a plastic-free future?

  • Imagine a sprawling dump with thin bags flapping in the wind, thousands of tonnes of plastic piling up creating mountains… The greatest claim in the last five years is that this vision can be fixed with the most surprising of allies: the worm.  Our common worm is often undervalued when it comes to soil fertility and recycling. Now it not only seems that our wriggling friend will solve global soil infertility issues, but our plastic problems too. In 2016 alone, 320 million tons of plastic was thrown away, some finding its way into landfills or littering thousands of kilometres of road, beach or mountain. However, 80% of these plastics break down, finding their way into marine environments. These microplastics, measuring less than 5mm and coming from a range of synthetic polymers, have even been found embedded in deep Arctic Ice and in deep waters such as the Mariana Trench. The number of seabirds estimated to have ingested plastic increased from 5% in 1960 to 90% in 2015. The far-reaching impact of plastics both on terrestrial life as well as biota at every single trophic level in marine habitats is public knowledge – and scientists have recommended the mighty mealworm and waxworm as our soldiers against plastic. 

    Mealworms, Tenebrio molitor, are the larval form of the mealworm beetle and have been proven to eat polystyrene and Styrofoam with no side effects noted at all. In 2019, scientists even added the toxic flame retardant hexabromocyclododecane and examined the toxic build up within the mealworms. The retardant has led to many health and environmental concerns with humans, causing endocrine disruption and severe neurotoxicity. The effects of this in the mealworm? Absolutely none – all toxicity was excreted within 48 hours, with 90% excreted in the first 24 hours. Even the shrimps which were fed the mealworms showed no signs of toxicity and had the same nutritional value as those fed on normal vegetation-eating mealworms. This opportunity to use plastic as a feed base for mealworms which could then be used as mass feed for chickens or other industry produced animals is ground-breaking – a waste product could be beneficially used and broken down at the same time. These worms break down the plastic using microorganisms in their gut which has led to further research with a different worm altogether: the waxworm.

    Waxworms, Galleria mellonella, live in beehives and break down the waxy polymer carbon chains produced by the bees. By some twist of nature, wax has a similar chemical structure to the plastic polythene the most widely used plastic found in all types of packaging and plastic bags. This fortunate correlation was discovered when a scientist clearing out her beehive, left the waxworms in a plastic bag for some time, and on her return they had chewed their way out. Although the rate at which they can eat polythene is too slow to viably use them in an industrial capacity, what they represent is still an under-researched potential method to seriously attack the plastic problem. It is thought they are able to digest these carbon polymers due to an evolved symbiosis with a bacterium that lives inside their digestive tract. The bacterium thought to be responsible for the breakdown of the plastics was identified by Japanese scientists as Ideonella sakaiensis; it uses two enzymes to biodegrade carbon polymers into terephthalic acid and ethylene glycol. Potential future research is already being discussed; integrating the enzyme-producing genes into E.coli for mass production of the protein would create large amounts of the plastic-eating enzyme, thereby allowing scientists to directly use the enzyme as a plastic-remover.

    These discoveries seem to be nature throwing us lifelines, a way out of a sticky situation choreographed by an unassuming worm. But if you take a moment to pause and reflect, the question remains: is this ethical? Can we justify force-feeding plastic to these worms just because humans are too lazy to manage plastic consumption and safe disposal of toxic materials? Beyond the moral concerns lie profound political complications. The UK is one of the largest plastic waste exporters in the world, leading to a ‘laissez faire’ attitude as the public never see mountains of waste piling up in our green fields. Currently, countries that import the waste, such as China and Malaysia, are tightening up on plastic levels themselves, causing the UK to look elsewhere for a different solution. Perhaps this political complication will lead to the worm being a timely arrival. Yet surely, as well as showing us how ingenious evolution can be for worms to digest complex polymers, these studies also demonstrate how desperate the plastic problem really is and where our focus truly needs to lie: reducing the amount of plastic waste we produce instead of genetically engineering an enzyme to fix the problem for us.