Polyethylene terephthalate (PET), a representative general-purpose plastic, is a material used in various applications, including PET bottles, clothing, seat belts, takeaway cups, and vehicle mats. The scientific community is working to find technologies that can easily decompose and recycle PET.
Recently, domestic researchers developed a biocatalyst technology to overcome the limitations of plastic recycling. The Ministry of Science and ICT announced that a research team led by Professor Kim Kyung-jin from Kyungpook National University and representatives from CJ CheilJedang developed the world's highest performance biocatalyst (PET depolymerase, PETase) for decomposing PET plastic. The research results were published in the international journal Science on the 3rd.
Most plastics are reused as intermediate products through 'mechanical recycling,' which involves separating, removing labels, crushing, washing, and refining. However, the quality of recycled materials often deteriorates, ultimately leading to incineration or landfill disposal. Although 'chemical recycling,' which uses chemical catalysts to melt PET plastic with heat or decompose it with solvents to create raw materials, has emerged, its application is limited due to raw material contamination, and it has not established itself as a perfect alternative due to its significant environmental impacts.
To address these issues, Professor Kim Kyung-jin's research team focused on 'biological recycling,' where biocatalysts mediate decomposition reactions, similar to how wood decays in the natural environment. They developed a high-performance biocatalyst (enzyme) that biologically decomposes PET plastic. This biocatalyst selectively reacts with PET, producing pure reaction products with minimal negative environmental impact during the plastic decomposition process, and the quality of the recycled material is excellent.
The research team developed an approach to map the biocatalysts possessed by microorganisms and predict their functions. Using this method, they discovered a new biocatalyst for decomposing PET called "Kubu." Based on Kubu's excellent potential, they also succeeded in developing a stronger improved biocatalyst called "Kubu M12" through enzyme engineering. Kubu M12 demonstrated the world's best performance by decomposing 45% of 1 kg of PET within 1 hour and over 90% in 8 hours, using only 0.58 g.
Professor Kim noted, "Biological recycling through biocatalysts is a groundbreaking technology that enables permanent recycling even for contaminated plastics that cannot be recycled. This research is significant because it recognizes the great potential of nature, and innovations utilizing biocatalysts will occur in various chemical industries in the future."
Reference materials
Science (2024), DOI: https://doi.org/10.1126/science.adp5637