In 2016, workers at a recycling plant in Sakai, Japan found that their plastics were degrading or in organic terms rotting away.
This was very unusual because plastic bottles are made from polyethylene terephthalate (PET), and it is notoriously difficult for microbes to break it down because PET’s molecular string is too large for the microbes, in simple terms, to swallow, and digest.
Because of this, many are concerned that our landfills and oceans will simply continue to fill with plastic.
But ‘rotting’ plastic had everyone’s attention and after researchers took a closer look, they discovered it was being caused by a plastic-eating bacteria.
Most plastics are insurmountable obstacles for microbes because plastics are large chains of repeating molecules called polymers. The entire chain is far larger than the individual microbe. “So the organism can’t take it inside the cell to metabolize it,” says John Coates, a microbiologist at the University of California, Berkeley who was not involved with the work. Imagine a baby trying to eat an enormous pizza from the middle. It can’t do it. The pie is too big.
But Ideonella sakaiensis, which we here at NPR have decided to call “the polymer chomper,” has two enzymes that can slice and dice the plastic polymer into smaller pieces. In other words, the baby gets a pizza cutter. The bacterium can then take the pieces and eat them, eventually converting the plastic into carbon dioxide and water.