PETase: an introduction

“Plastic disposal not only pollutes the land but the water and the air, the three primary elements for any living being on the Earth” - Sir P.S. Jagadeesh Kumar

Discovery and First Usage


PETase was discovered in Ideonella sakaiensis, a bacterium found in a Japanese recycling plant in 2016 by Shosuke Yoshida and his team at the Kyoto Institute of Technology. (The Story of PETase, the Plastic Eating Enzyme, 2018) PETase represented the first natural enzyme shown to directly break down PET into its basic monomers, terephthalic acid and ethylene glycol, that are more easily biodegradable than PET (Science, 2016). The researchers not only discovered the enzyme but also proved its ability to break down PET plastic under controlled laboratory circumstances. This was the first evidence that a natural enzyme (PETase) could directly target and degrade PET. (Yoshida et al., 2016)

Conditions Leading to the Evolution of PETase


PETase evolution was shaped by human-made conditions, specifically the buildup of polyethylene terephthalate (PET) in ecosystems. Since the 1970s, huge amounts of PET have been generated and thrown in landfills, rivers, and soils, resulting in plastic-rich environments where microorganisms are continually exposed to this synthetic polymer (Soong et al., 2024). At a PET bottle recycling facility in Japan, I. sakaiensis was shown to have gained the ability to use PET as a carbon source, showing selective pressure created by plastic waste (Yoshida et al., 2016).

Availability


PETase is naturally very rare and only found in I. sakaiensis. Today, the PETase gene has been cloned so that researchers can produce it in lab organisms like Escherichia coli (Kim et al., 2016). Engineered and more efficient versions exist and are being tested for industrial use; however, they are not yet sold as a general commercial enzyme.

PETase Influence in Biodegradation


The discovery of PETase for I. sakaiensis in 2016 was an influential turning point in the field of biodegradation and plastic recycling. Before its discovery, PET, one of the most commonly used plastics, was thought to be highly resistant to natural degradation, contributing significantly to global plastic pollution (Yoshida et al., 2016). Yoshida et al. showed for the first time that a bacterium could not only break down but also use PET as a carbon source, indicating that microbes may adapt to man-made polymers. This result sparked a surge of interest in enzyme-based recycling as an alternative to the existing mechanical and chemical processes, which are frequently expensive (energy consumption) and inefficient (Hampson, 2016). Thailand-RIS aims to continue this legacy through novel expression of PETase in a eukaryotic organism, namely plants, to act as agents of bioremediation.

References:

  1. GROUP, C. (2018). The Story of PETase, the Plastic Eating Enzyme. Agchemigroup.eu. https://www.agchemigroup.eu/tr/blog/post/story-petase-plastic-eating-enzyme
  2. Hampson, M. (2016, March 9). Science: Newly Identified Bacteria Break Down Tough Plastic | American Association for the Advancement of Science. Www.aaas.org. https://www.aaas.org/news/science-newly-identified-bacteria-break-down-tough-plastic
  3. Kim, J. W., Park, S.-B., Tran, Q.-G., Cho, D.-H., Choi, D.-Y., Lee, Y. J., & Kim, H.-S. (2020). Functional expression of polyethylene terephthalate-degrading enzyme (PETase) in green microalgae. Microbial Cell Factories, 19(1). https://doi.org/10.1186/s12934-020-01355-8
  4. Soong, Y.-H. V., Sobkowicz, M. J., & Xie, D. (2022). Recent Advances in Biological Recycling of Polyethylene Terephthalate (PET) Plastic Wastes. Bioengineering, 9(3), 98. https://doi.org/10.3390/bioengineering9030098
  5. Yoshida, S., Hiraga, K., Takehana, T., Taniguchi, I., Yamaji, H., Maeda, Y., Toyohara, K., Miyamoto, K., Kimura, Y., & Oda, K. (2016). A Bacterium That Degrades and Assimilates poly(ethylene terephthalate). Science, 351(6278), 1196–1199. https://doi.org/10.1126/science.aad6359