Science

Watch as a ‘Pac-man’ enzyme devours plastic and becomes a solution to one of the world’s biggest environmental disasters

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A protein “similar” to “Pac-Man”, which has a particular appetite for plastic, could pave the way to solving one of the biggest environmental problems in the world: the billions of tons of waste in landfills. Researchers at the University of Texas at Austin, USA, developed this special enzyme to destroy PET (polyethylene terephthalate), a substance commonly used by manufacturers of food and beverage packaging, textiles and fibers .

Its development, the study of which was published in the journal ‘Nature’, offered the hope of helping to solve global pollution, allowing complete recycling of plastic waste, which could allow large industries to recover and reuse products at the molecular level. “The possibilities are endless across all industries to take advantage of this state-of-the-art recycling process,” explained Hal Arper, who was responsible for the study.

“In addition to the obvious waste management industry, it also offers companies in all sectors the opportunity to lead the way in recycling their products. Thanks to these more sustainable enzymatic approaches, we can begin to envisage a true circular economy of plastics,” explains the researcher.

PET accounts for around 12% of all global waste – like all plastics, it is made up of long “string-like” molecules. The enzyme manages to break it down into smaller parts before chemical “recycling”. In some cases, plastics only take 24 to 48 hours to fully decompose. In the oceans, for example, these products can survive for centuries.

The enzyme development process had the collaboration of artificial intelligence (AI), which generated new mutations in a naturally occurring enzyme called PETase, which allows bacteria to degrade PET – the computer neural network identified the most effective mutations below 122 degrees Fahrenheit (50 degrees Celsius), making it portable and affordable. Dozens of discarded plastic items were analyzed, including containers, water bottles, polyester fibers and fabrics – all made with PET. “This work has really demonstrated the power of bringing together different disciplines, from synthetic biology to chemical engineering to artificial intelligence,” says study co-author Andrew Ellington.

In 2020, the world produced 367 million tonnes of plastic, of which less than 10% ended up being recycled. After sending this material to landfills, burning is the second most common method of plastic disposal. However, the environmental consequences are extreme, with the release of harmful gases into the air. Alternative industrial processes exist but are quite energy-intensive, while biological solutions require much less effort.

The study authors revealed they were increasing production of the enzyme to prepare for industrial and environmental applications – the Texas team has filed for a patent and is eyeing several different uses, including landfill cleanup and manufacturing high-end industries to produce greener waste. “When considering environmental cleaning applications, you will need an enzyme that can function in the normal temperature environment. It is in this requirement that our technology has a huge advantage in the future,” concluded Hal Arper.

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