Nearly complete depolymerization of untreated post-consumer plastic with an immobilized and reusable PET hydrolase

Area of Science:

• Biotechnology
• Environmental Science
• Materials Science

Background:

• Plastic accumulation, particularly polyethylene terephthalate (PET), poses a significant environmental challenge.
• Enzyme-based biodegradation offers a sustainable route for PET recycling, but industrial application is hindered by biocatalyst immobilization and reusability issues.

Purpose of the Study:

• To introduce IC-Tagging, a novel one-step method for "in cellulo" self-immobilization of PET-degrading enzymes.
• To evaluate the performance of immobilized enzymes in terms of activity, stability, and reusability for PET depolymerization.

Main Methods:

• Utilized IC-Tagging for the self-immobilization of LCC^ICCG enzyme within protein nanospheres.
• Assessed the activity of immobilized LCC^ICCG against soluble substrates.
• Investigated the thermal resistance, storage stability, and reusability of the immobilized enzyme over multiple cycles.
• Evaluated the depolymerization efficiency of post-consumer PET materials under various temperature conditions.

Main Results:

• Immobilized LCC^ICCG retained 58% activity after 3 months at room temperature and showed minor activity loss over 10 reuse cycles.
• Achieved over 90% depolymerization of untreated post-consumer PET materials at temperatures ranging from 50-70 °C.
• Demonstrated nearly complete degradation of two consecutive PET batches within 6 days through repeated enzyme reutilization, outperforming existing lab-scale immobilized biocatalysts.

Conclusions:

• IC-Tagging is a versatile platform for producing, immobilizing, and reusing high-performance PET hydrolases.
• This method significantly enhances enzyme stability and reusability, crucial for industrial PET recycling.
• The approach contributes to the sustainable management of plastic waste by enabling efficient PET biodegradation.