Complete bio-degradation of poly(butylene adipate-co-terephthalate) via engineered cutinases

Area of Science:

• Biotechnology
• Polymer Science
• Environmental Science

Background:

• Poly(butylene adipate-co-terephthalate) (PBAT) is a widely used plastic that contributes to global environmental waste.
• Effective biodegradation of PBAT requires potent enzymes, and cutinases are being investigated for this purpose.

Purpose of the Study:

• To evaluate the efficacy of cutinases in degrading PBAT.
• To engineer cutinases for improved PBAT decomposition rates.
• To elucidate the mechanism of cutinase-mediated PBAT degradation.

Main Methods:

• Enzymatic degradation assays using PBAT films.
• Protein engineering via site-directed mutagenesis (double mutation strategy).
• X-ray crystallography to determine enzyme-substrate complex structures.
• Biochemical analyses to understand degradation mechanisms.

Main Results:

• Cutinases demonstrated complete decomposition of PBAT films within 48 hours.
• Engineered cutinases with modified substrate-binding pockets exhibited significantly higher degradation rates.
• Terephthalic acid (TPA) was identified as the major end-product of degradation by engineered variants.
• Crystal structures revealed substrate-binding modes of wild-type and engineered cutinases.

Conclusions:

• Cutinases are effective biocatalysts for PBAT degradation.
• Enzyme engineering can enhance PBAT decomposition efficiency.
• The production of TPA offers potential for a circular plastic economy and recycling.