The Microbe That Eats Plastic—and Might Save Us All

In the ongoing fight against the global plastic crisis, a microscopic hero has emerged—one that could revolutionize waste management and reshape our environmental future.

Meet Ideonella sakaiensis 201-F6, a bacterium discovered by a team of Japanese scientists in 2016 at a PET bottle recycling facility in Sakai, Japan. This unassuming microbe made headlines when researchers found it could not only survive on polyethylene terephthalate (PET)—the most common type of plastic used in water bottles—but actually break it down and use it as a source of carbon and energy.

According to the World Economic Forum, the world produces approximately 400 million metric tons of plastic waste annually, with over 8 million metric tons entering the world’s oceans every year. PET alone accounts for around 10% of global plastic production. Despite recycling efforts, only about 9% of plastic waste is recycled worldwide, leaving the rest to languish in landfills or pollute the environment for centuries.

Enter I. sakaiensis. In laboratory experiments, researchers observed that this bacterium could degrade a thin film of PET in approximately six weeks—an impressive feat, considering that PET can persist in the environment for 450 years or more. Its secret weapon: a pair of enzymes—PETase and MHETase—that work together to break down PET into its building blocks, which the bacterium then consumes.

Dr. Yuka Matsui, a microbiologist at Kyoto University, explains: “The PETase enzyme effectively breaks apart the polymer chains of PET, while MHETase further degrades the byproducts. Together, they can reduce a plastic bottle into its fundamental components.”

So what happens to those byproducts? As the bacterium’s enzymes work, PET plastic is first broken down into MHET (mono-(2-hydroxyethyl) terephthalic acid). MHETase then breaks that into two main products: terephthalic acid (TPA) and ethylene glycol (EG). Remarkably, both of these substances are non-toxic and are either metabolized by the bacteria as carbon and energy sources—producing carbon dioxide and water in the process—or can be recovered and potentially reused.

This clean breakdown is a huge advantage. Unlike chemical recycling processes, which can produce hazardous byproducts, I. sakaiensis leaves behind nothing dangerous. In industrial settings, the TPA and EG could be captured and purified to produce new PET, effectively creating a closed-loop recycling process. Ethylene glycol, for example, can be used in antifreeze, polyester resins, or other industrial applications, while TPA is a key component for making fresh plastic.

Recent studies have focused on enhancing the efficiency of these enzymes. In 2021, a team at the University of Portsmouth in the UK engineered a “super enzyme” by combining PETase and MHETase into a single molecular unit. This hybrid enzyme accelerated the breakdown process by up to three times, reducing the time needed to degrade PET waste by half. Early trials have shown that this enzyme can degrade PET by 90% in just ten days—a potentially game-changing leap forward.

The implications are staggering. If scaled effectively, these microbes—or their engineered enzymes—could process the 29 million metric tons of PET plastic currently produced every year. Even if they handled just 20% of global PET waste annually, that would amount to nearly 6 million metric tons of plastic diverted from landfills and oceans.

But challenges remain. While the enzymes work well under controlled laboratory conditions, real-world waste streams are often contaminated with dyes, additives, and mixed materials that can inhibit the microbes’ efficiency. “Industrial-scale deployment will require preprocessing steps to remove contaminants and optimize conditions,” notes Dr. Matsui.

Moreover, questions about unintended ecological consequences persist. Could genetically modified microbes escape and disrupt natural ecosystems? Environmental groups have called for strict containment measures and thorough testing before large-scale use.

Despite these hurdles, the excitement surrounding I. sakaiensis and its supercharged enzymes is palpable. At a time when plastic waste threatens marine life, food safety, and even human health—some studies estimate that people ingest up to 5 grams of microplastics per week, equivalent to a credit card’s weight—these tiny organisms offer a glimmer of hope.

As researchers race to refine the technology, one thing is clear: the humble bacterium from a Japanese recycling plant may well be the key to cleaning up a planet drowning in plastic—without leaving a dangerous footprint behind.