More than 220 million tons of plastic are produced each year, and despite greater emphasis on recycling programs, much of it gets dumped in landfills and oceans around the world. The U.S., for example, only recycles about 14% of the nearly 33 million tons of plastic containers and packaging that winds up in American landfills every year.
Now Japanese researchers are debuting what could be a tiny solution to the big plastic problem. Ideonella sakaiensis 201-F6 is a bacteria that eats PET, a polymer commonly used in plastics that’s nearly impossible to biodegrade. (You can see the full study in the March 11 edition of Science.) When placed on PET, I. sakaiensis attaches to the polymer and degrades it into into an intermediate substance called mono(2-hydroxyethyl) terephthalic acid—MHET for short. From there, a second enzyme breaks the MHET into the two basic building blocks of PET. That process may not sound too exciting to people who aren’t hardcore chemistry fans, but I. sakaiensis’ ability to both eliminate PET waste and separate the polymer into its own basic ingredients makes this bacteria twice as useful to scientists.
With I. sakaiensis, "you have the chance to get rid of the PET waste because you can degrade it," says Uwe T. Bornscheuer, a biochemist at Greifswald University in Germany who was not involved in the research. (We couldn't reach the researchers before this article went live.) "The other option is if you don’t want to degrade it, you can break it down to the monomers and you can make new [PET] polymer out of it."
The catch is that I. sakaiensis takes its sweet time. In a lab, the bacteria took six weeks to demolish a thin film of PET, which means that it’s not a quick fix for the mountains of empty shampoo and water bottles piling up in your local landfill. But that may not always be the case. Researchers not only found and isolated the bacteria, they also sequenced its genome, which could allow future researchers to build bigger, better PET-annihilating bugs down the road.
"When we understand the underlying principals, then we can [potentially] improve the strain to make it better and faster," Bornscheuer says, adding that genetically modified bacteria would have to be used in controlled settings to avoid disrupting outside environments. "We can take this information and the knowledge to put it into other microorganisms which we can engineer in the lab."
I. sakaiensis isn’t the only plastic-eating organism created by Mother Nature. Certain varieties of fungi, marine microbes, and worms all break down various components of plastic, but none degraded the substance as thoroughly as I. sakaiensis. That bacterial efficiency in dealing with a man-made compound that was only introduced in the last century may be an indicator of how the Earth is evolving in response to the massive amounts of synthetic waste humans dump on it every day. Unlocking the secrets of plastic-eating organisms like I. sakaiensis could be both a start in cleaning up the plastic problem as well as a tool to help researchers understand how nature adapts to man-made materials and how long that evolution takes Bornscheuer says.
As impressive as the discovery is, don’t count on a single bacteria to end all of the world’s plastic woes. Not all plastics are composed of PET and even the ones that are often contain other compounds that I. sakaiensis can’t vanquish. Bornscheuer isn’t discouraged by those limitations.
"To my knowledge, this is the first bacteria that can fully degrade PET," he says. "…For sure many scientists will see this as a great achievement but also as a new starting point for their own research."