Algae-Powered Plastic Recycling: Green Microalgae Secret PHL7 Enzyme to Tackle PET Pollution

In a world drowning in plastic, scientists at the University of California San Diego have engineered the green algae Chlamydomonas reinhardtii to efficiently secrete a plastic-degrading enzyme called PHL7, capable of breaking down the toughest plastic waste—including PET (polyethylene terephthalate) and bio-based polyurethane.

By using a bioengineered vector system, the research team was able to induce secretion of PHL7 directly into the culture media, offering a low-energy, scalable, and carbon-neutral solution to one of Earth’s most pressing environmental crises.

Why This Matters

Over 450 million tons of plastic are produced annually
Only 5–6% of plastics were recycled in 2021
Microplastics are now found in food, oceans, and even human blood
Current plastic recycling is costly, inefficient, and energy-intensive

This study brings the world a step closer to biological upcycling, where plastic waste is broken down into reusable components using living organisms—and potentially even used as feedstock for new, sustainable bioplastics.

Key Research Highlights

Engineered algae secrete PHL7, eliminating the need for expensive cell lysis and purification

PHL7 degrades PET into terephthalic acid (TPA), verified by mass spectrometry

Algal strains showed high enzymatic activity in degrading Impranil and sPU plastics

Two proposed strategies:

Integrated system: Algae grow and degrade plastic simultaneously
Compartmentalized system: Algae grow separately, and enzymes are harvested for industrial use

Enzyme secretion detected using halo assays, FDA cleavage, and zymogram gel analysis

Supports the circular economy—where algae can secrete enzymes and later be converted into biofuels, bioplastics, or feed

Real-World Impact

The algae-powered enzyme system can be deployed for:

Plastic cleanup in oceans and soil
On-site degradation units at recycling centers
Bioreactors for PET breakdown into monomers
Sustainable production of bioplastic precursors

What’s Next?

The team is currently exploring:

Techno-economic analyses (TEA) and life cycle assessments (LCA)
Metabolic engineering to allow algae to “eat” degraded plastic and grow faster
Integration into bio-industrial supply chains to replace fossil-based plastics

Reference

Dutra Molino, J.V., Saucedo, B., Kang, K. et al. Efficient secretion of a plastic degrading enzyme from the green algae Chlamydomonas reinhardtii. Sci Rep 15, 24690 (2025). https://doi.org/10.1038/s41598-025-09100-0