A bacterial enzyme found in composting heaps has been found to be partial to chowing down on more than just decaying leaves. The study published in the journal Nature hypothesizes that the breakthrough will provide a green avenue for processing plastic bottles so that they can be used again.
Around 359 million tons of plastics are produced annually, 150-200 million tons of which end up in the landfill or the environment. Man-made plastics have been found almost everywhere, from remote beaches to the bottom of the deepest known point of the ocean.
Polyethylene terephthalate (PET) is the most abundant polyester plastic, with almost 70 million tons manufactured worldwide every year for use in everything from packaging to textiles. Existing recycling technologies are able to process the sorts of plastic bottles we accrue when enjoying fizzy drinks or bottles of water, but previously the product yielded at the end of processing was only fit for use in clothing or carpets. The bacterial enzyme uncovered in composting is capable of breaking down plastic bottles to chemical building blocks that can be manipulated back into a bottle, making 100 percent recyclable plastic bottles an aim for the first time.
The discovery was made by researchers from the University of Toulouse after 100,000 microorganisms were studied to highlight any potential candidates for the role, and a bacterium involved in leaf composting was one of those chosen. The researchers introduced mutations in an attempt to encourage the bacterial enzyme’s efficacy for processing PET. When tested on one ton of plastic bottles, the enzyme successfully degraded 90 percent of the PET in just 10 hours.
While reducing plastic use in our daily lives is a vital step in clawing back the plague of plastic currently inflicting the globe, this hardy material still plays a role in modern life. As a hardy and light-weight material, there are certain functions that just can’t yet be fulfilled by some of the “greener” alternatives such as glass and metal (for example, in medicine where cost-effective equipment is key).
While the improvement in processing yield is a big step forward, the research still has some way to go before it's ready to take on the world's plastic plague. In light of the discovery, the research team has partnered with plastic-bottle aficionados Pepsi and L’Oréal. Together, they hope to fast-track refining the details of the process so that industrial-scale recycling can be achieved within five years. The time taken to achieve the breakdown is promising for scaling up the process, but it will still need to be refined in order to meet the demands of the world's plastic waste.