A mutant enzyme that breaks down plastic in hours
A new breed of plastic-eating bacterial enzymes could be used to create high quality new bottles for recycling in the near future.
The enzyme breaks down plastic in a matter of hours and is already being speculated to reduce plastic waste by breaking it down to its chemical building blocks, which can then be used to make other products.
Carbios, the company behind the breakthrough, announced their intent to have this produced on an industrial scale within five years when they partnered with several other companies, including Nestlé and Pepsi in April of last year. [1]
The new enzyme, PETase – able to break down the plastic polymer Polyethylene terephthalate (PET) – was revealed in research published on Wednesday [2], and is based on prior research into thousands of micro-organisms dating back to 2012, with the enzyme itself being reported in an issue of Proceedings of the National Academy of Sciences Journal in 2018. [3]
With over 8 million tonnes of plastic being dumped into the oceans every year, [4] there has been a rallying cry by governments across the globe to reduce dependency on plastics by 2030, with independent experts calling this a major advance in carbon-neutral plastic production and the enabling of true recycling.
The enzyme was found in a compost heap of leaves and went under the radar until the research team funded by Carbios screened it before the breakthrough.
Professor Alain Marty, the chief science officer at Carbios said: “It had been completely forgotten and it turned out to be the best. The scientists analysed the enzyme and introduced mutations to improve its capability to break down the PET polymer from which the majority of plastic bottles are made.
“These mutations also made it stable at 72°C, which is very close to the perfect temperature for fast degradation.”
The team used the enzyme to break down a tonne of plastic, which had degraded by 90% within 10 hours. This material was then used in the creation of food-grade plastic bottles.
With the estimation that there will be more plastic than fish in the ocean by 2050 [5], the race is on to provide a completely sustainable form of plastic production.
However, plastic recycling is not without its problems. 91% of all plastic bottles used are not recycled [6] and demand for all plastic goods fluctuates every year.
The EU’s recent ban on plastic straws [7] is hoped to reduce levels of plastic waste entering the oceans, predominantly due to the fact that very few of them enter the recycling process [8] and many have an expected biodegrade time of approximately 200 years. Unfortunately, not enough time has elapsed to fully comprehend its effects.
There is also the adverse effect that many plastics are created from petrochemicals produced by oil and gas [9], meaning that plastic’s inextricable link to fossil fuels further proves its danger to the environment in the wake of renewable energy sources coming into the foreground.
Back in 2018, another research group stated they had accidentally created an enzyme that breaks down plastic drinks bottles [10] based on the discovery of plastic-eating bugs found at a Japanese landfill.
Professor John McGeehan, the director of the Centre for Enzyme Innovation at the University of Portsmouth said that Carbios were the leading innovators in mass-producing enzymes to break down PET-based plastics.
He said: “It makes the possibility of true industrial-scale biological recycling of PET a possibility. This is a huge advancement in the field.
“It represents a significant step in reducing our reliance on oil, cutting carbon emissions and energy use, and also incentivises the collection and recycling of waste plastic.”
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