Mutant, plastic-eating enzyme joins the bottle party
The discovery has been met with euphoria - and a word of caution - by environmental groups
It happened by accident: scientists have improved on a naturally occurring enzyme, and discovered that it can digest some of our worst plastics that are polluting the world at unprecedented rates.
This could, further along the line, have a major impact in South Africa.
PET, the plastic mainly used for bottles, takes hundreds of years to be broken down in the environment. The new enzyme, PETase, can break down the material in just a few days.
Behind the revolutionary research are the University of Portsmouth and the US Department of Energy’s National Renewable Energy Laboratory.
Professor John McGeehan, of the University of Portsmouth, and the team were studying the crystal structure of an enzyme that occurs in nature to see how it slowly eats away at the bottles.
During the research the team engineered a mutant version purely by accident, and discovered it did the work of eating at the plastic much faster than the one mother nature had designed.The researchers at the National Renewable Energy Laboratory in the US said that “while the invention of highly durable plastics has had positive impacts for humankind’s quality of life”, it was that very same durability that was “causing the plastics pollution problem”.
The structure of PET is too crystalline to be easily broken down and, while PET can be recycled, most of it is not, and furthermore, although bio-based, the plastic is not biodegradable and “would still end up as waste in landfills and in the seas”.
Because of this massive global pollution problem on account of PET, the accidental discovery has been met with euphoria across science and environmental groups alike.A few voices of caution, however, have risen above the hype and excitement. One such voice is Don Loepp, author of The Plastics Blog.
“Don’t get me wrong ... This could be a low-cost way to recycle PET back into brand-new, virgin-quality resin,” he wrote, “But let’s keep this in mind: The big issue with PET recycling isn't a technological barrier or even a litter problem.
“PET bottles are easy to recycle, and there’s a big market for them.
“The big problem with PET bottles is that people don’t put them all in their recycling bins. And fortunately for us, we know how to solve the problem because there are systems set up all over the world that work. They’re called bottle deposits.”
Petco, the South African recycling PET company, has urged South Africans to climb on board the recycling wagon.
The organisation said “plastic bottles are not trash” and PET bottles are a “valuable resource”.But, “when discarded on landfill sites, instead of recycled, that value is lost”. Recycling one ton of PET bottles saves 1.5 tons of CO2 emissions.
“There are many different ways of recycling plastic bottles. Curbside recycling takes place in some areas, or sometimes you have to take your recyclables to a nearby drop-off centre.”
Recycling plastic bottles “decreases the need for raw materials and saves energy. Do not let your plastic bottles end their valuable lives on a landfill,” the organisation urged.
Where to now?
The goal of the team responsible for the latest research is “to use their findings to continue to improve the new enzymes to break down these man-made plastics, but in a fraction of the time of current methods”.
“Few could have predicted that in the space of 50 years, single-use plastics such as drink bottles would be found washed up on beaches across the globe,” said McGeehan.
“We can all play a significant part in dealing with the plastic problem. But the scientific community who ultimately created these ‘wonder materials’ must now use all the technology at their disposal to develop real solutions.”