Quantcast
Environmental News for a Healthier Planet and Life

Help Support EcoWatch

Mutant Enzyme Recycles Plastic in Hours, Could Revolutionize Recycling Industry

Science
Mutant Enzyme Recycles Plastic in Hours, Could Revolutionize Recycling Industry

A garbage yard in Lucknow, India where plastic bottles are dumped before being sent to recycling. Abhimanyu Kumar Sharma / Moment / Getty Images

Scientists have engineered a mutant enzyme that converts 90 percent of plastic bottles back to pristine starting materials that can then be used to produce new high-quality bottles in just hours. The discovery could revolutionize the recycling industry, which currently saves about 30 percent of PET plastics from landfills, reported Science Magazine.



Poly(ethylene terephthalate) (PET) is the plastic used in soda bottles, textiles and packaging. With almost 70 million tons manufactured annually worldwide, it is also the most abundant polyester plastic because it is strong and lightweight, explains the study's abstract, which was published in Nature.

Unfortunately, current PET recycling is inefficient. When plastics of different colors are melted down during the recycling process, a gray or black plastic starting material results that few companies want to purchase to package their products, explained Science Magazine. The process results in low-grade plastic fibers only good enough for clothing and carpets, reported The Guardian. These eventually end up in a landfill or incinerated, added Science Magazine.

"It's not really recycling at all," explained professor John McGeehan, the director of the Centre for Enzyme Innovation at the University of Portsmouth, to Science Magazine.

McGeehan, who was not involved in the research, called the new enzyme "a huge step forward," reported Science Magazine. He also noted that Carbios, the French sustainable plastics company behind the breakthrough, is the industry leader in engineering enzymes to break down PET at large scale, reported The Guardian.

For years, scientists at the forefront of the cultural war on plastic waste have searched for microbial enzymes that could break down PET and other plastics. Recently, a group of German scientists discovered a bacterium that breaks down polyurethane plastic and uses it for food to fuel the process, but cautioned it might be a decade before commercial scale could be reached. Similarly, in 2018, researchers led by McGeehan accidentally discovered an enzyme that digests PET, but noted that it doesn't do so very quickly (a few days). Even the base enzyme used in Carbios' research, leaf-branch compost cutinase (LLC) has been studied since 2012, when it was discovered in a compost heap of leaves by researchers at Osaka University, reported Science Magazine.

The team at Carbios screened 100,000 micro-organisms for promising candidates, and eventually began introducing mutations to LLC. Native LLC falls apart after just a few days of working at 65°C, the temperature at which PET begins to soften but not yet melt, explained Science Magazine.

The researchers re-engineered LLC to work faster and at higher temperatures. Alain Marty, Carbios' chief scientific officer, teamed up with Isabelle Andre, an enzyme engineering expert at the University of Toulouse, to isolate an optimized enzyme that is 10,000 times more efficient at breaking down the chemical bonds in PET than native LLC, reported Science Magazine. It also functions at 72°C, close to the temperature at which PET melts, making the process even more efficient.

The mutant enzyme broke down 90% of 200 grams of PET in a small reactor in just 10 hours. Different colors didn't matter because the enzyme can ignore dyes and other plastics in the molten mix. The researchers were able to use the resultant chemical building blocks to produce new PET and food-grade plastic bottles that were just as strong as those made from virgin plastics, reported Science Magazine.

"It's a real breakthrough in the recycling and manufacturing of PET," said Dr. Saleh Jabarin, a member of Carbios' scientific committee in a company statement about the discovery. "Thanks to the innovative technology developed by Carbios, the PET industry will become truly circular, which is the goal for all players in this industry, especially brand-owners, PET producers and our civilization as a whole."

Carbios reports that the enzyme costs just 4% of what virgin plastic made from oil costs, noted The Guardian. The enzyme cannot be added to waste plastic until it is ground up and melted, however, so the recycled PET is still more expensive than virgin plastic. Still, McGeehan noted to Science Magazine that companies may be willing to pay a bit more for a recycled plastic that is as durable and attractive as the virgin material.

Carbios is partnering with major companies, including Pepsi and L'Oréal, to accelerate development and produce the new enzyme at scale, reported The Guardian. It is aiming for industrial-scale recycling within five years. Science Magazine reported that a demonstration plant that can recycle hundreds of tons of PET per year should be online by next year.

"We are the first company to bring this technology on the market," said Martin Stephan, the deputy chief executive at Carbios, to The Guardian. "Our goal is to be up and running by 2024, 2025, at large industrial scale."

McGeehan explained to The Guardian that the discovery could finally make true industrial-scale biological recycling of PET a possibility. The new enzyme is faster, more efficient and more heat-tolerant — qualities that make this such a large advancement for the field, he added.

McGeehan said, "It represents a significant step forward for true circular recycling of PET and has the potential to reduce our reliance on oil, cut carbon emissions and energy use, and incentivize the collection and recycling of waste plastic," reported The Guardian.

EcoWatch Daily Newsletter

A resident works in the vegetable garden of the Favela Nova Esperanca – a "green favela" which reuses everything and is subject to the ethics of permaculture – in the outskirts of Sao Paulo, Brazil, on Feb. 14, 2020. NELSON ALMEIDA / AFP via Getty Images

Farmers are the stewards of our planet's precious soil, one of the least understood and untapped defenses against climate change. Because of its massive potential to store carbon and foundational role in growing our food supply, soil makes farming a solution for both climate change and food security.

Read More Show Less
Once the virus escapes into the air inside a building, you have two options: bring in fresh air from outside or remove the virus from the air inside the building. Halfpoint Images / Getty Images

By Shelly Miller

The vast majority of SARS-CoV-2 transmission occurs indoors, most of it from the inhalation of airborne particles that contain the coronavirus. The best way to prevent the virus from spreading in a home or business would be to simply keep infected people away. But this is hard to do when an estimated 40% of cases are asymptomatic and asymptomatic people can still spread the coronavirus to others.

Read More Show Less
California Senator Kamala Harris endorses Democratic presidential candidate Joe Biden at a campaign rally at Renaissance High School in Detroit, Michigan on March 9, 2020. JEFF KOWALSKY / AFP via Getty Images

Former Vice President Joe Biden made a historic announcement Tuesday when he named California Senator Kamala Harris as his running mate in the 2020 presidential election.

Read More Show Less
An aerial view taken on August 8, 2020 shows a large patch of leaked oil from the MV Wakashio off the coast of Mauritius. STRINGER / AFP / Getty Images

The tiny island nation of Mauritius, known for its turquoise waters, vibrant corals and diverse ecosystem, is in the midst of an environmental catastrophe after a Japanese cargo ship struck a reef off the country's coast two weeks ago. That ship, which is still intact, has since leaked more than 1,000 metric tons of oil into the Indian Ocean. Now, a greater threat looms, as a growing crack in the ship's hull might cause the ship to split in two and release the rest of the ship's oil into the water, NPR reported.

On Friday, Prime Minister Pravind Jugnauth declared a state of environmental emergency.

France has sent a military aircraft carrying pollution control equipment from the nearby island of Reunion to help mitigate the disaster. Additionally, Japan has sent a six-member team to assist as well, the BBC reported.

The teams are working to pump out the remaining oil from the ship, which was believed to be carrying 4,000 metric tons of fuel.

"We are expecting the worst," Mauritian Wildlife Foundation manager Jean Hugues Gardenne said on Monday, The Weather Channel reported. "The ship is showing really big, big cracks. We believe it will break into two at any time, at the maximum within two days. So much oil remains in the ship, so the disaster could become much worse. It's important to remove as much oil as possible. Helicopters are taking out the fuel little by little, ton by ton."

Sunil Dowarkasing, a former strategist for Greenpeace International and former member of parliament in Mauritius, told CNN that the ship contains three oil tanks. The one that ruptured has stopped leaking oil, giving disaster crews time to use a tanker and salvage teams to remove oil from the other two tanks before the ship splits.

By the end of Tuesday, the crew had removed over 1,000 metric tons of oil from the ship, NPR reported, leaving about 1,800 metric tons of oil and diesel, according to the company that owns the ship. So far the frantic efforts are paying off. Earlier today, a local police chief told BBC that there were still 700 metric tons aboard the ship.

The oil spill has already killed marine animals and turned the turquoise water black. It's also threatening the long-term viability of the country's coral reefs, lagoons and shoreline, NBC News reported.

"We are starting to see dead fish. We are starting to see animals like crabs covered in oil, we are starting to see seabirds covered in oil, including some which could not be rescued," said Vikash Tatayah, conservation director at Mauritius Wildlife Foundation, according to The Weather Channel.

While the Mauritian authorities have asked residents to leave the clean-up to officials, locals have organized to help.

"People have realized that they need to take things into their hands. We are here to protect our fauna and flora," environmental activist Ashok Subron said in an AFP story.

Reuters reported that sugar cane leaves, plastic bottles and human hair donated by locals are being sewn into makeshift booms.

Human hair absorbs oil, but not water, so scientists have long suggested it as a material to contain oil spills, Gizmodo reported. Mauritians are currently collecting as much human hair as possible to contribute to the booms, which consist of tubes and nets that float on the water to trap the oil.

A northern mockingbird on June 24, 2016. Renee Grayson / CC BY 2.0

Environmentalists and ornithologists found a friend in a federal court on Tuesday when a judge struck down a Trump administration attempt to allow polluters to kill birds without repercussions through rewriting the Migratory Treaty Bird Act (MBTA).

Read More Show Less
A spiny dogfish shark swims in the Olympic Coast National Marine Sanctuary off the coast of Washington. NOAA / Wikimedia Commons

By Elizabeth Claire Alberts

There are trillions of microplastics in the ocean — they bob on the surface, float through the water column, and accumulate in clusters on the seafloor. With plastic being so ubiquitous, it's inevitable that marine organisms, such as sharks, will ingest them.

Read More Show Less

Trending

A "vessel of opportunity" skims oil spilled after the Deepwater Horizon well blowout in the Gulf of Mexico in April 2010. NOAA / Flickr / CC by 2.0

By Loveday Wright and Stuart Braun

After a Japanese-owned oil tanker struck a reef off Mauritius on July 25, a prolonged period of inaction is threatening to become an ecological disaster.

Read More Show Less