A High-Sensitivity Genetically Encoded Biosensor for Terephthalic Acid Detection in PET Degradation

Area of Science:

• Biotechnology
• Environmental Science
• Synthetic Biology

Background:

• Polyethylene terephthalate (PET) waste accumulation presents a significant environmental challenge due to its recalcitrance.
• Enzymatic hydrolysis of PET is a promising sustainable degradation method.
• Current high-throughput screening tools for PET-degrading enzymes are limited.

Purpose of the Study:

• To develop a genetically encoded biosensor (GEB) for rapid and sensitive detection of terephthalic acid (TPA), a key PET degradation product.
• To engineer an efficient biosensor system in *Escherichia coli* for enhanced TPA detection.
• To establish a scalable platform for identifying and optimizing PET-degrading enzymes.

Main Methods:

• Engineered a TphR-based biosensor in *Escherichia coli* by combining an optimized transcriptional system with diverse TPA uptake transporters.
• Optimized intracellular TPA accumulation through transporter selection and genetic component tuning.
• Validated the biosensor's performance using various PETases and compared results with High-Performance Liquid Chromatography (HPLC) assays.

Main Results:

• Achieved a detection limit of 1 μM TPA, representing a 1,000-fold sensitivity improvement over the initial design.
• The best-performing biosensor configuration demonstrated enhanced signal intensity and a broader detection range.
• Successfully distinguished between different PETase variants based on their hydrolytic activity.

Conclusions:

• The developed GEB provides a rapid, scalable, and ultrasensitive platform for monitoring PET hydrolysis.
• This biosensor serves as a robust, low-cost alternative to conventional analytical methods.
• The engineered biosensor accelerates the discovery and optimization of enzymes for PET upcycling and circular bioeconomy applications.