Rewriting E. coli’s Genome: A New Biotech Path to Tackle Nanoplastic Pollution

Redacción HC
12/09/2025

Plastics are among the most enduring pollutants of the 21st century. Among them, polyethylene terephthalate (PET) stands out for its ubiquity in bottles, textiles, and packaging. Over time, PET breaks down into microscopic and nanoscopic fragments that infiltrate ecosystems and food webs. These nanoplastics (nPET) are particularly concerning because they are nearly impossible to recover through conventional recycling or filtration methods, posing risks to both environmental and human health.

A recent study published in Trends in Biotechnology introduces a breakthrough approach: computationally guided genome rewiring of Escherichia coli. Instead of inserting foreign DNA, researchers redesigned the bacterium’s native proteins to give them the ability to degrade PET and even channel the byproducts into valuable compounds. This method represents a paradigm shift in biotechnology, potentially bypassing regulatory hurdles while tackling one of the world’s most pressing waste problems.

Why Nanoplastics Matter

PET is one of the most widely produced plastics globally, and its persistence in the environment has long been a concern. As larger plastics fragment, the resulting nanoplastics disperse widely in water, soil, and even the atmosphere. Their small size allows them to be ingested by organisms ranging from plankton to humans, raising alarm over possible toxicological effects.

While enzymes capable of degrading PET have been identified in certain bacteria, transferring these enzymes into model organisms like Escherichia coli has raised safety and regulatory concerns. The team behind this study asked a fundamental question: could native Escherichia coli proteins be repurposed to degrade PET without the need to insert external genes?

The Computational-to-Experimental Workflow

The researchers built a four-step pipeline that blends computational biology with genome editing:

1. In silico screening – Native Escherichia coli proteins were computationally scanned for structural potential to adopt PETase-like activity.
2. Rational design – Simulated mutations were introduced to optimize binding and catalytic activity against PET fragments.
3. Genome rewiring via CRISPR/Cas9 – Native genes were replaced by redesigned versions, maintaining the bacterium’s genomic integrity without foreign DNA insertion.
4. Functional testing – Engineered Escherichia coli strains were evaluated for their ability to degrade PET and nanoplastics, while also assessing their ability to metabolize the degradation products.

Key Findings

A particularly compelling case emerged with the periplasmic transport protein LsrB. Computational modeling suggested that LsrB could be redesigned to bind PET fragments. After targeted mutations and genomic substitution, the modified protein displayed PET and nPET degradation activity in laboratory tests.

Crucially, some engineered variants functioned at 37 °C, making them suitable for industrial fermentation processes. The bacteria not only degraded nanoplastics but also repurposed the breakdown products into useful metabolites, demonstrating both biodegradation and upcycling.

Quantitatively, while the modified enzymes were less efficient than naturally evolved PETases from specialized bacteria, they still showed significant catalytic activity. More importantly, the approach validates a concept: reprogramming native cellular machinery rather than importing foreign genes.

Practical and Industrial Implications

If scaled successfully, this technique could transform how we address plastic waste. Instead of exporting PET waste or relying solely on physical recycling, industries could deploy biorefineries using reprogrammed Escherichia coli to process plastics into valuable products such as precursors for bioplastics or specialty chemicals.

The study highlights that avoiding foreign DNA could ease public and regulatory acceptance. Nevertheless, strict safeguards would remain essential, such as kill-switches to prevent unintended release and careful monitoring for gene transfer risks.

In Latin America, where plastic waste management poses urgent challenges, this strategy could be integrated into regional recycling plants. By transforming PET locally, the method could strengthen circular economies while creating value-added products.

Next Steps for Research

• Improving enzyme efficiency through directed evolution.
• Scaling production in bioreactors under industrial conditions.
• Testing performance on mixed plastic waste streams rather than purified PET.
• Conducting life-cycle assessments to verify environmental net benefits.

They also emphasize the importance of developing regulatory frameworks tailored to organisms that are genetically rewired without foreign DNA, a relatively uncharted field in biotechnology governance.

Conclusion

By reprogramming Escherichia coli to degrade and recycle plastics, scientists have opened a promising new frontier in the fight against plastic pollution. The approach blends computational power, genome editing, and environmental biotechnology to tackle an urgent global issue.

While still at the proof-of-concept stage, this strategy could reshape how societies handle PET waste, shifting from disposal to transformation. The balance between innovation, safety, and regulation will determine how quickly this technology moves from the lab to industrial applications.

Topics of interest

Technology