An accidental discovery may have exciting implications for solving the global crisis caused by plastic pollution noticed that waxworms that she placed in a plastic shopping bag when cleaning out her beehives quickly ate through the bag, leaving it riddled with holes. This type of material is difficult to break down and although plastic recycling definitely helps with the problem, a huge number of plastic bags end up in a landfill or polluting the world’s oceans. Plastic packaging, including plastic bags, is commonly made from polyethylene.
Further research into Ms Bertocchini’s discovery was carried out by Dr Paolo Bombelli from Cambridge University. To confirm that the breakdown of the plastic was not simply due to the chewing mechanism of the waxworms, some of them were “mashed up” by the researchers and smeared onto polyethylene bags, and this proved to have a similar effect of degrading the material.
Waxworms commonly live in beehives, where they digest the wax, and scientists believe that the enzymes in their gut or saliva attack the chemical bonds in the plastic, in the same way as they attack the beeswax. The researchers are hopeful that, if this chemical process is caused by a single enzyme, it may be possible to reproduce it on a large scale for use in existing plastic recycling plants. It could then be used to biodegrade plastics in these plants and in the future, possibly be sprayed on to landfill sites directly or even added to sea plants in order to degrade waste plastic that is already present in the environment.
The scientists at Cambridge University released one hundred waxworms on a plastic supermarket shopping bag. After just forty minutes, holes started appearing and over twelve hours, the waxworms consumed 92 mg of the plastic. This compares very favourably with the results from previous trials using bacteria, in which only 0.13 mg of plastic was consumed in 24 hours.
Using spectroscopic analysis, the Cambridge scientists, together with researchers from the Institute of Biomedicine and Biotechnology of Cantabria, concluded that the chemical bonds in the plastic were broken down through exposure to the waxworms. The polyethylene was transformed into ethylene glycol, an unbounded substance. The study suggested that the process of digesting wax in beehives is a similar process, involving breaking down the same type of bonds.
Despite fairly widespread plastic recycling operations, there is still a great deal of plastic polluting the environment, and British supermarkets have been encouraged to consider introducing plastic free aisles to combat this. According to research from the Ellen MacArthur Foundation, there is likely to be a greater weight of plastic than fish in the oceans by 2050. Scientists have pointed out that, alongside initiatives aimed at degrading plastics, efforts to reduce the amount used in the first place are also very important.
The use of plastic for shopping bags has fallen by as much as 80 percent since October 2015, when a charge of 5 pence for each bag was introduced by retailers with more than 250 employees. A similar charge of up to 20 pence may also soon be levied on plastic bottles, but this would be refundable when they were recycled.