Engineered microbes to enable a circular economy for biodegradable plastics

Area of Science:

• Biotechnology and Biochemical Engineering
• Environmental Science and Sustainability
• Polymer Science

Background:

• Plastic pollution from fossil-derived polymers is a global challenge.
• Biodegradable plastics offer alternatives but face limitations like incomplete degradation and infrastructure gaps, hindering true circularity.
• Current approaches often overlook the potential for upcycling plastic monomers into valuable products.

Purpose of the Study:

• To advance a circular bioeconomy framework for biodegradable and synthetic plastics using engineered depolymerization and metabolic bio-funneling.
• To review progress in enzyme-mediated plastic breakdown and microbial upcycling strategies.
• To evaluate chemo-biological hybrid systems and techno-economic aspects for scalable plastic upcycling.

Main Methods:

• Enzyme-mediated depolymerization of polyesters using hydrolases and oxidoreductases.
• Metabolic bio-funneling of plastic-derived monomers into central metabolic pathways (pyruvate, acetyl-CoA, aromatic/dicarboxylate).
• Application of systems biology, adaptive laboratory evolution, synthetic consortia, and machine learning for microbial platform development.

Main Results:

• Demonstrated strategies for redirecting plastic monomers toward platform chemicals, fuels, and biopolymers via pathway engineering.
• Evaluated chemo-biological hybrid systems and key techno-economic factors like enzyme cost and process efficiency.
• Highlighted advanced tools for accelerating the development of microbial platforms for plastic upcycling.

Conclusions:

• Biodegradable plastics can be viewed as programmable carbon reservoirs, not just disposable materials.
• Engineered bio-upcycling provides a practical route to close the loop, aligning plastic utility with environmental sustainability.
• This approach is crucial for achieving a truly circular bioeconomy and mitigating plastic pollution.