Every year, eight million tonnes of plastic waste either end up in the sea, or as landfill. Is there a sustainable solution to stop this cycle? Or, at the very least, to slow it down? Recent research has provided results that might just contain the answer we’ve been looking for.
Two years ago, Federica Bertocchini – amateur beekeeper, as well as science researcher – made a curious discovery. The larvae of wax moths (Galleria mellonella) are not only known for their use as fishing bait, but also for the problems they cause to beekeepers (the creatures live on beeswax). Bertocchini, having placed the larvae into a plastic bag to prevent them from swarming her hives, found that the larvae were able to chew their way out. “I went back to the room where I had left the worms and I found that they were everywhere, the bag was full of holes,” Bertocchini said.
This discovery prompted Bertocchini and other scientists at Cambridge University to begin examining the eating patterns of waxworms. Upon placing the larvae upon polyethylene plastic, they discovered that each worm could create almost two holes per hour. To put this into context – in under a month, 100 worms could degrade (on average) 5.5 grams of plastic! This far exceeds previous bacteria-based attempts, that managed to degrade only 0.13mg of plastic per day.
To prove that the worms weren’t simply releasing smaller pieces of plastic (due to the mechanical movement of the masticatory system), Bertocchini and colleagues smeared blended larvae onto the plastic and then… waited. Surprisingly, they found that even the waxworms liquid could create holes in the plastic. This outcome convinced the team that it was either an enzyme (in their saliva, or their gut) or bacteria in the larvae that were capable of degrading plastic.
…this discovery might just turn the tables on the ways in which the battle against plastic waste is being fought
Spectroscopy analysis – measuring the light absorbed, emitted or dispersed by a material – was used to confirm the degradation of plastic following contact with homogenate larvae. The scientists concluded that waxworms could breakdown plastic using the same enzymes that they use to eat beeswax; by attacking the chemical bonds within polyethylene, the worms transform it into an “un-bonded” material named ethylene glycol (a chemical regularly used within antifreeze). A very high-resolution type of skimming probe microscopy only provided more evidence supporting the idea that the larvae are capable of modifying the unity of polyethylene.
Commenting on these findings, Paolo Bombelli (a biochemist at Cambridge University) said, “…if a single enzyme is responsible for this chemical process, its reproduction on a large scale using biotechnological methods should be achievable.” Bombelli seems to believe that the results of this research are promising, and have the potential to lead to a solution for the problem of plastic waste.
From here, the next step is finding which enzyme specifically is involved in the degeneration. And… after that? The range of possibilities is wide. The compound could be inserted into either bacteria or phytoplankton, in order to reduce the amount of plastic waste in uninhabited regions. Furthermore, the findings could potentially be tailored to an industrial scale (considering the larvae’s ability to degrade even the hardest of plastics). Finally, the enzymes might be spattered directly onto locations such as landfill sites.
This discovery might just turn the tables on the ways in which the battle against plastic waste is being fought. I am hopeful that it provides the possibility of moving away from the endless accumulation of plastic in landfills and seas, and towards the biodegradation of plastics. For the time being, however – let’s carry on trying to reuse more, and produce less.