May 1st, 2017
This news has made headlines since 24th April when it was first published in the scientific journal, Current Biology – about the discovery of caterpillars that find munching on plastic, fantastic. There have been wide speculations and hope that they prove to be hungry enough to help us get rid of substantial amounts of plastic, the non-biodegradable pollutant which remains in landfills and oceans for years.
Chance discovery of the caterpillars
The discovery of the plastic eating wax worms was accidental and incidental. It happened when a scientist and amateur beekeeper, Federica Bertocchini of the Institute of Biomedicine and Biotechnology of Cantabria in Spain was disgruntled at seeing one of her beehives at home infested with wax worms. She decided to clean the beehive, keeping the wax worms in a common plastic shopping bag while she went about her business. She had kept the plastic bag with the worms in it in another room. When she returned to the room she was surprised to see the worms crawling everywhere. The plastic bag was riddled with holes. This meant that the wax worms had chewed their way out of the plastic bags at a relatively high speed.
Genesis of a scientific project
This chance discovery gave birth to a properly conducted scientific research in collaboration with scientists at the University of Cambridge in England. Their aim was to determine whether these wax worms could be used to resolve the global plastic crisis, as published in the journal, Current Biology on 24th April 2017.
In the words of Bertocchini and her colleagues, about 100 wax worms had chewed their way out of a polyethylene shopping bag in around 40 minutes. The bag was significantly shredded within a span of just 12 hours.
The researchers wanted to make sure whether the worms were just chewing through the plastic or actually eating it. Hence, they smashed the worms and smeared the plastic with the paste for observation. They noticed that about 13% of the plastic had disappeared after 14 hours!
This led the scientists to believe that there was some compound in the digestive system of the worms that enabled the digestion of the plastic. On thorough analysis of the residual chewed up plastic bag, they also discovered ethylene glycol, the main compound in antifreeze, “confirming [polyethylene] degradation.”
Wax worms are commercially harvested to be used as fishing baits and are commonly found in beehives. They lay eggs in beehives. It is their natural habitat and diet that leads to their ability to break the chemical bond made up of carbon, found in beehives. Scientists are not yet sure of what exactly helps the worms. However, as stated by Paolo Bombelli from Cambridge University, “The caterpillar produces something that breaks the chemical bond, perhaps in its salivary glands or a symbiotic bacteria in its gut.”
It is to be noted that wax has a chemically similar structure to the wax found in beehives. These caterpillars are known to wreck havoc to the beehives by eating their combs. They live off the beehives like parasites.
Implication in terms of plastic waste solution
As stated earlier, about 100 wax worms were able to make holes in a plastic bag within 40 minutes and reduce it by 92 mg in 2 hours. In other words, the plastic-eating bacteria in the worms were capable of biodegrading plastic at a rate of 0.13 mg per day.
If our readers are yet to understand the implication of this speed, polyethylene plastic found in landfills takes 100 to 400 years to degrade. About 1 trillion plastic bags are consumed by people around the world annually, demanding a production of more than 45 million tons of polyethylene plastics in a year.
Given such a scenario, the chance discovery of the capability of wax worms to biodegrade plastic within such a short span of time is nothing less than revolutionary.
Other similar experiments conducted earlier
In order to understand the implications of this discovery better, we need to compare it with the search of other biological “digesters” which could enable plastic degradation in a speedy manner. For example, in 2011, a fungus was discovered with the capacity to erode polyurethane which is another kind of plastic that largely composes the trash heaps and ocean wastes around the globe.
Further, in 2014, a team of researchers had discovered that bacteria within wax worms’ digestive system happened to degrade polyethylene, but only after an interval of two months.
As compared to this, the chance discovery by Bertocchini and the experiments conducted by her collaborators show that the current wax worms are able to speed up the biodegradation at a phenomenal speed.
Although there has been much hype about the plastic-eating property of wax worms, some scientists have warned that the solution of plastic waste is not as simple as it meets the eye. To begin with, these wax worms are known to devastate beehives, thus distressing bee population. Galleria mellonella, the wax worm species on which the current experiment was conducted, is one of the two species of wax worms that are considered to have caused damage to more than £4m worth of damage annually in the United States alone. Chances are that if they are bred in billions, the number required to make any significant dent on the plastic problem, they might harm the neighbouring ecosystem.
The right way
Even though the wax worms have been found to wreck much more damage to plastic than their earlier counterparts, it is still not clear what exactly makes the biodegradation possible. The research team aims to pinpoint whether a single enzyme is responsible for this chemical process. If so, “its reproduction on a large scale using biotechnological methods should be achievable.” This would also be economically more viable than breeding wax worms.
Alternatively, it is being speculated that the bacteria found in wax worms and responsible for biodegrading the plastic would prove to be the key. It would be possible to ferment the bacteria in vats, without depending on wax moth colonies. This would also prevent any damage to the ecosystem.
The Logical Indian team hails the discovery of plastic-eating wax worms and hopes that the research team is able to find a way forward and bring about a major breakthrough in solving the problem of plastic pollutant which is a cause of serious concern for environmentalists across the world!