The Planet

Japanese Researchers Discover Plastic-Eating Bacterium

by DJ Pangburn

March 11, 2016
Photo via Flickr user Lisa Risager

While Japanese designers recently created a seaweed-based alternative to plastic packaging, another group of Japanese researchers were busy discovering a novel bacterium that can eat plastic. The engineering team behind the discovery published their findings in a paper Friday in the journal Science.

The bacterium, which they named Ideonella sakaiensis 201-F6, secretes two enzymes—PETase and MHETase—that break down the common plastic polymer polyethylene terephthalate, or PET. As the researchers explained in their paper, both enzymes are required to “enzymatically convert PET efficiently into its two environmentally benign monomers, terephthalic acid and ethylene glycol.” The PETase enzyme breaks down PET into the compound MHET, and the MHETase enzyme breaks it down even further.

“The researchers collected 250 environmental samples, such as soil and sludge, from the yard of a PET bottle-recycling factory and analyzed many different species of bacteria that were growing within the samples,” the American Association for the Advancement of Science, publisher of Science, reported. It noted that Ideonella sakaiensis 201-F6 could almost completely degrade a thin film of PET after six weeks, at a temperature of 86 degrees Fahrenheit.

AAAS added that the Japanese researchers were somewhat surprised at the existence of the plastic-eating bacterium. Their discovery of Ideonella sakaiensis suggests that it is recently evolved.

“We are surprised at the presence of this bacterium that degrades and assimilates PET, whose commercial production was initiated only [a little more than] 60 years ago, meaning that during such a short time the 201-F6 have evolved an efficient system to metabolize PET,” said Keio University’s Shosuke Yoshida, one of the paper’s authors.

While the research is promising, Yoshida cautioned that the bacterium degrades plastic at a level too low for industrial application. That said, he believes this discovery could lead to future breakthroughs in an engineered plastic-eating enzyme.

“We have to answer the fundamental questions such as why PETase is more active and specific to PET compared to other PET-[degrading] enzymes,” he added, “which could lead to creating the engineered enzyme appropriate for the practical use in the future.”

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Japanese Researchers Discover Plastic-Eating Bacterium