Have you ever thought about where your recycled plastics typically end up? In the best-case scenario, plastics are recycled to fleece, then to carpets, and eventually end up in the landfill. The quality of the plastic decreases with each cycle, and the material takes over 400 years to decompose in nature, not making it a very efficient system. However, our current global recycling systems could soon be facing a massive overhaul, with the use of Mother Nature’s most widespread helper: bacteria.
Earlier this year, researchers discovered a naturally occurring enzyme that digests PET plastic. The bacterium from which the enzyme is derived, Ideonella sakaiensis, was first uncovered at a Japanese bottle recycling plant in 2016. British researchers isolated the bacteria and, interested in the enzyme’s evolution, tweaked the structure only to discover that they had inadvertently improved the enzyme’s degradation capacity, speeding up the process by 20%. This news has huge positive implications for the future of plastics across the globe.
Polyethylene terephthalate, or PET, is the synthetic material commonly found in plastic bottles and was developed in the 1940s. The polyester was thought to be a “wonder-product” during its conception for its strength, lightness, and extreme durability, yet its greatest strength is also proving to be its greatest weakness, taking 450-1000 years to degrade fully. To make matters worse, over the years PET plastic has saturated the consumer market, with an estimated one million plastic bottles being sold every minute across the globe.
Thankfully, the discovery of this “plastic-eating” enzyme could revolutionize the plastic recycling and production industries. Functionally, the enzyme works by reversing the manufacturing process. It breaks PET down into its original building blocks, from which plastics can be re-synthesized. The process takes a few days for completion, boasting a vast improvement over the centuries that it typically takes. Additionally, the enzyme ensures that clear plastic bottles can be recycled back into clear plastic, instead of the opaque fibres that we see in current recycling processes. This key element slashes the need to produce virgin plastic from oil, encouraging the close of the plastic recycling loop.
The discovery is generating serious interest among scientists and industry alike. The 20% increase in function confirms that the enzyme is not fully optimized yet, and there is vast potential for further molecular engineering. This has inspired the researchers at Britain’s University of Portsmouth to continue digging into the matter. Another suggested research avenue suggests transplanting the enzyme into an “extremophile” bacterium that can survive at high temperatures. When heated above 70C, PET changes from a glassy to a viscous state, making it likely to degrade 10-100 times faster. Eventually, scientists are hopeful that these plastic-eating bacteria will be put to work on the massive garbage patches that pervade the world’s oceans.
Certainly, challenges exist in transforming the research into industrial applications, such as the development of a cheap method for producing the enzyme. Potential funding for this research is not known as of yet. However, it begs the question of whether the responsibility lies in the hands of big plastic producers, such as Coca-Cola, to close the loop on their production cycle.
The recent “PET-ase” enzyme is a startling discovery that has awed scientists across the globe. Plastic pollution has reached unprecedented proportions, and this bacterial enzyme presents a potential solution for reducing plastic in landfills and in the environment. Effectively, the future of plastic pollution is up against a new, Nature-made competitor with vast hidden potential.
Carrington, D. (2018, April18). Scientists accidentally create mutant enzyme that eats plastic bottles. The Guardian. Retrieved from: https://bit.ly/2HCCZOX
Halton, M. (2018, April 16). Recycling hope for plastic-eating enzyme. BBC News. Retrieved from: https://bbc.in/2JOAc62
Kellandd, K., McDill, S. (2018, April 16). Plastic-eating enzyme holds promise in fighting pollution. Reuters. Retrieved from: https://reut.rs/2qGuF8T
Nace, T. (2017, July 26). We’re now at a million plastic bottles per minute – 91% of which are not recycled. Forbes Magazine. Retrieved from: https://bit.ly/2jLAwqz
PET Resin Association. (2015). About PET. Retrieved from: https://bit.ly/2G2iFEm
Yoshida, S., Hiraga, K., Takehana, T., Taniguchi, I., Yamaji, H., Maeda, Y.& Oda, K. (2016). A bacterium that degrades and assimilates poly (ethylene terephthalate). Science, 351(6278), 1196-1199.