Meet the Enzyme That Eats Plastic
A mutant enzyme, created accidentally by scientists, eats up plastic waste, potentially helping to solve the planet’s growing plastic problem. Sounds like the stuff of science fiction, right?
Yet it’s exactly what happened at a waste dump in Japan. In 2016, after spending five years searching through piles of waste, Japanese researchers discovered a strain of bacteria that naturally evolved to eat away at one of the most common plastics in the world: polyethylene terephthalate, also known as PET or polyester.
The Japanese research team sifted through hundreds of samples of PET pollution before finding a colony of organisms using the plastic as a food source. After further testing, they found that the bacteria almost completely “ate” low-quality plastic within six weeks—incredibly speedy compared to other bacteria.
The discovery was just the first step in utilizing this biological tool to aid in the fight against plastic pollution. After uncovering the detailed structure of the bacteria found in the Japanese waste dump, an international team of scientists went on to test and tweak the enzyme, studying it further.
The structure of the enzyme looked very similar to one evolved by many bacteria to break down cutin, a natural polymer used as a protective coating by plants. But when the team manipulated the enzyme to explore this connection, they accidentally improved its ability to eat PET.
That’s right: They had only made the plastic-eating bacteria stronger.
Inadvertently, the team had shortened the mutant enzyme’s plastic-eating process from six weeks to mere days. Far faster, of course, than the centuries it takes in our oceans.
Researchers are hopeful this process can be sped up even further, ultimately become a viable large-scale solution to plastic waste.
Professor John McGeehan at the University of Portsmouth, who led the research, told The Guardian his team hopes to use the enzyme to turn plastic back into its original components—literally recycling plastic back into plastic, a process Pregis has built into both our core values and how we do business. “It means we won’t need to dig up any more oil and, fundamentally, it should reduce the amount of plastic in the environment,” McGeehan said.
Worldwide, about one million plastic bottles are sold every minute. Currently, just 14 percent of those bottles are recycled, but even those that do get properly recycled can only be turned into opaque fibers for clothing or carpets. Our current recycling processes mean these polyester materials follow only a downward spiral in terms of quality, losing some of their properties each time they go through the cycle. Bottles become fleeces, then carpets, then...they often end up in landfill.
This mutant enzyme could reverse the manufacturing process, reducing polyesters to their building blocks, ready to be used again.
The plastic-eating enzyme could provide a way to recycle clear plastic bottles back into clear plastic bottles, cutting the need to produce new plastic.
Enzymes are already widely used in washing powders and biofuel production, and even these have been made to work up to 1,000 times faster in the last few years. A patent has been filed on the mutant enzyme by both McGeehan’s team of researchers in Portsmouth, U.K., and those from the U.S. National Renewable Energy Laboratory in Colorado.
One possible improvement being explored is to transplant the mutant enzyme into an “extremophile bacteria,” meaning it can survive higher temperatures and possibly degrade 10-100 times faster.
But even at a much larger scale and faster rate, can the mutant enzyme really solve our planet’s massive plastic problem?
According to the Washington, D.C.-based nonprofit Ocean Conservancy, the answer to that question is no. In their response to the new study, Ocean Conservancy cites the real problem: Not breaking down the plastic, but removing the plastic from the ocean. Instead, the conservancy suggests putting effort into keeping plastics out of the ocean in the first place.
As research has repeatedly shown, plastics are an ever-growing problem for the world’s oceans. A 2015 study found that roughly eight million tons of plastics make it into the ocean each year. All that plastic is detrimental to wildlife, as many seabirds and other marine life mistake plastic for food, get caught and tangled in debris, or worse.
Other challenges lie ahead in turning what is currently a hopeful discovery into a real-world application. Developing a technique for producing the enzyme cheaply will be one key hurdle; another will be to harness its power on an industrial scale.
The plastic-eating enzyme is still a number of years away from being utilized on a such a scale. It will need to degrade plastic faster than its current time of a few days before becoming economically viable as part of the recycling landscape, but McGeehan told The Guardian he’s hopeful.
"There is an urgent need to reduce the amount of plastic that ends up in landfill and the environment, and I think if we can adopt these technologies we actually have a potential solution in the future to doing that, McGeehan said.
Not all researchers see these discoveries, however revolutionary, as the answer to the global pollution crisis, writes CityLab’s Linda Poon. First, there’s the question about practicality. All of the plastic to be eaten would need to be located in one place in order to effectively apply the enzyme. Other criticisms include calls to recycle rather than degrade. Plastic, some critics argue, generally has more value as a recycled material than it does broken down into water and carbon dioxide—the goal of biodegradation. The enzyme McGeehan worked with breaks plastic into its raw materials; if the goal is to use those materials to make new bottles, technology for that already exists.
Technological innovation is important, but the more fundamental issue is how waste is handled, some argue. In the United States, not all cities have made recycling a mandatory element of waste collection. Others view recycling as too pricey, compared to the low- or no-cost short-term solution of simply throwing things away (short-term, of course, because our planet is feeling the effects of such practices). The calls for recycling are even more bleak outside the U.S., particularly in low-income countries where the task falls on informal waste collectors who are both underpaid and underappreciated.
Of course, like nearly all environmental problems, plastic pollution has several dimensions and needs to be tackled from all angles, wrote Poon in her CityLab piece. “If the history of scientific breakthroughs is any indication, the accidental discoveries of super enzymes and plastic-eating worms may, at the very least, leave a footprint in our ongoing battle to save the Earth from waste.”
At Pregis, we’ve teamed up with the Sustainable Packaging Coalition in effort to encourage the proper recycling of packaging material. (Learn more about this partnership and how we make this process happen here!).
As experts stated, recycling remains an incredibly valuable tool in the fight against plastic pollution. Fortunately, your local recycling center is another helpful resource to learn more about how to recycle everyday items in your community. Contact your local recycling center to find out more.