Enzymatic and microbial recycling of bio-based plastics (PLA and PHA) into high-value monomers

Overview

This research program develops an enzymatic and microbial recycling platform for bio-based plastics, specifically polylactic acid (PLA) and polyhydroxyalkanoates (PHA), which are increasingly used in sustainable packaging. The process depolymerizes these plastics into their constituent monomers and then ferments those monomers into new polymers or high-value chemicals, creating a circular pathway that diverts bio-based packaging from landfill and reduces reliance on fossil-derived inputs.

The approach addresses two converging market pressures: growing regulatory and consumer demand for genuinely recyclable packaging, and corporate net-zero commitments that require lower-carbon material cycles. The work is intended to validate integration into real packaging operations and demonstrate both environmental and economic viability at scale.

Technical specifications

Recycling workflow:

• Pre-treatment steps including washing and grinding to remove impurities such as food residues, labels, and adhesives
• Enzymatic hydrolysis using proteases, lipases, and PHA depolymerases to break PLA and PHA down into lactic acid and hydroxyalkanoic acid monomers
• Microbial fermentation using lactic acid bacteria and engineered organisms including Amycolatopsis, Saccharothrix, and engineered E. coli to convert monomers into new PLA, new PHA polymers, or other high-value chemicals
• Downstream purification using distillation and chromatography to isolate and purify monomers from impurities
• The process is designed to produce starting materials and high-value-added chemicals rather than fuels, preserving the material value of the recycled plastics

Key features:

• Targets two of the most commercially relevant bio-based packaging polymers
• Combines enzymatic specificity with microbial metabolism for high-yield monomer recovery
• Outputs can feed directly back into polymer manufacturing, enabling closed-loop packaging
• Avoids combustion of recycled plastic, supporting lower greenhouse gas emissions

Technology readiness level

The hypothesis has not yet been validated experimentally. Near-term validation requires detailed laboratory studies on enzymatic and microbial depolymerization efficiency, optimization of fermentation yields, and assessment of economic feasibility and environmental sustainability. The current stage is early-stage applied research, with the next milestone being bench-scale experimental validation of the combined enzymatic and fermentation process.