Newly Identified Bacteria Degrades Common Plastic
A new species of bacteria able to degrade one of the world's most common plastics has been discovered by Japanese scientists. Polyethylene terephthalate, or PET, is the plastic usually found in disposable water bottles. The discovery by researchers from Kyoto Institute of Technology and Keio University indicates that the biodegradation of plastics by specialized bacteria could be a viable bioremediation strategy.
To find the bacteria, the team of researchers led by Shosuke Yoshida collected 250 PET-contaminated samples including sediment, soil and wastewater from a plastic bottle recycling site. Using these samples, they screened for microorganisms that could use low-crystallinity PET film as the major carbon source for growth. They found a consortium of microbes that appeared to break down the PET film, however just one of the bacteria species, named Ideonella sakaiensis, was responsible for PET degradation.
When grown on PET, I. sakaiensis produces two enzymes capable of hydrolyzing PET and the reaction intermediate, mono(2-hydroxyethyl) terephthalic acid. Both enzymes – a PETase and a MHETase – are required to enzymatically convert PET efficiently into its two environmentally benign monomers, terephthalic acid and ethylene glycol.
Although previous studies have detected species of fungi able to grow on PET, this is the first time microbes able to consume the substance have ever been discovered.
S. Yoshida, K. Hiraga, T. Takehana, I. Taniguchi, H. Yamaji, Y. Maeda, K. Toyohara, K. Miyamoto, Y. Kimura, K. Oda, A bacterium that degrades and assimilates poly(ethylene terephthalate) – DOI: 10.1126/science.aad6359