By Diana Abbasi, C2ST Intern, Rush University
Plastic pollution has become one of the most overwhelming environmental issues of our time. The effects of this type of pollution are wide-ranging, impacting wildlife, climate, and human health. No one wants to see images of sea turtles trapped in fishing nets or read about hazardous plastic byproducts contaminating our land and animals dying from starvation because their stomachs are filled with indigestible plastic, but that’s the current reality we live in.
Plastics originate as fossil fuels and contribute to greenhouse gas emission from cradle to grave. From refining, manufacturing, and waste management, plastic doesn’t stop polluting our planet once it enters the environment. Research suggests that 12% of our plastic has been destroyed and only 9% of plastic is recycled, leaving 79% of plastic to accumulate in our landfills and oceans. Our planet is choking on plastic, but thanks to a process called biorecycling there may be a light at the end of the tunnel.
Biorecycling is a natural process where organisms convert complex materials into new, useful materials. In 2016, a group of Japanese researchers discovered the first species of bacteria, Ideonella sakaiensis 201-F6, that naturally evolved to enzymatically (note: see definition below) break down the most used form of plastic, polyethylene, the polymer used to create plastic bottles and bags. Since this discovery, a research group at the University of Portsmouth, UK studied this bacteria to understand how the bacteria evolved to produce an enzyme capable of breaking down plastic. In 2018, the UK group accidently created a mutant version of the enzyme that was more efficient at breaking down polyethylene. Their mutant enzyme breaks down plastic within two days, which is faster than the centuries it takes to naturally break down in the ocean or a landfill. Professor John McGeehan, who led this research, hopes to optimize this enzyme and use it on a larger scale to aid the global plastic pollution crisis. He aims to use this enzyme to enable the full recycling of plastic bottles for the first time in history.
However, not all plastic is created equal. Polyurethane, a very commonly used polymer used in items such as sponges, paint, shoes, and foam insulation, is often sent to landfills because it is too tough to recycle. When broken down, this form of plastic releases toxic and carcinogenic chemicals and would kill most bacteria strains. In 2020, researchers at Helmholtz Centre for Environmental Research-UFZ in Leipzig, Germany published their discovery of the first bacteria that is able to break down polyurethane and use the plastic as a source of carbon, nitrogen, and energy to facilitate the degradation process. The bacteria is a new strain of Pseudomonas bacteria, a family of bacteria known for its ability to withstand extreme conditions such as highly acidic environments and can potentially be used to solve the issue of polyurethane plastics accumulating in our landfills. A major question raised by scientists is why these various bacteria strains naturally evolve to break down plastic. The reality is, many scientists believe that this is evolution being combative against the waste we’re producing.
The use of biorecycling for plastic pollution management is still in pioneer stages of research, but nonetheless, it is a promising method for environmental cleanup. That being said, biorecycling will not provide us with an end-all be-all solution to the problem of plastic pollution. It remains vitally important that we stop pollution before it happens by curbing the release of plastic into the environment.
Enzyme: proteins produced by a living organism that are used as catalysts to speed up the rate of a chemical reaction. In the context of this article, the bacteria, Ideonella sakaiensis 201-F6, uses its two enzymes, ISF6_4831 and ISFG_0224, to break down polyethylene as its major energy and carbon source.