Session: Government Agency Student Posters

Paper Number: 173156

Engineering Erwinia Sp. Ljjl01 as a Next-Generation Microbial Cell Factory for Pet Upcycling to Enable a Circular Bioeconomy. 

Each year, over 175 million metric tons of plastic waste accumulate in landfills and marine environments worldwide, with polyethylene terephthalate (PET) accounting for a significant portion due to its high durability and persistently low recycling rates. Traditional recycling methods often face economic and technical limitations, underscoring the urgent need for biochemical technology that can provide circular economy solutions, enabling the selective depolymerization of plastics and their upcycling into sustainable, high-value products. In this context, we present Erwinia sp. LJJL01 as a new, robust microbial chassis aimed at integrating biological PET depolymerization with the bioconversion of degraded monomers into valuable platform chemicals.

The genomic and phenomic studies unveiled that Erwinia sp. LJJL01 can be engineered to utilize the PET hydrolysate containing terephthalic acid and ethylene glycol for bio-upcycling into high-value di-acids (e.g., cis,cis-muconate). Notably, toxicity tolerance assays revealed high EC₅₀ values for ethylene glycol (663.3 mM), terephthalic acid (94.5 mM), adipic acid (121.6 mM), and glycolaldehyde (33.3 mM), an intermediate compound. These results reinforce its suitability as a robust microbial host for plastic upcycling.

To harness its capacity, we developed a tailored synthetic biology toolkit for Erwinia sp. LJJL01, including stable plasmid expression systems, characterized promoter libraries, and CRISPR-Cas9/CRISPRi genome editing. We successfully achieved the heterologous expression of a thermostable variant of the leaf-branch compost cutinase (LCC) enzyme. Bench-scale PET film and Bis (2-hydroxyethyl) terephthalate degradation assays confirmed the effectiveness of enzymatic depolymerization under both mesophilic and thermophilic conditions. We are currently working to enhance the enzyme secretion and reduce feedback inhibition by PET-derived monomers.

To guide the engineering of rational pathways, we combined transcriptomics (RNA seq) and proteomics to map the regulatory responses under PET-monomer exposure. These multi-omics data reveal oxidative stress responses, membrane transport systems, and activation of aromatic catabolism, providing a system-level basis for resolving metabolic bottlenecks. Aligned with circular economy principles, our downstream engineering efforts focus on channeling PET-derived monomers and aromatic intermediates into high-value platform chemicals such as cis,cis-muconic acid, 3-hydroxypropionic acid, and β-ketoadipic acid. These compounds are critical precursors for renewable bioplastics, synthetic fibers, and biodegradable solvents, creating closed-loop pathways that minimize waste and extend product life cycles. We envision that ongoing omics-based metabolic engineering efforts will make the strain more resilient for upcycling PET at an industrially applicable scale.

In conclusion, this study emphasizes Erwinia sp. LJJL01 as a promising next-generation microbial cell factory for upcycling PET. By integrating comprehensive metabolic characterization with advanced synthetic biology tools and omics-guided design, we demonstrate the potential of converting post-consumer PET into valuable platform chemicals. This approach supports a sustainable bioeconomy and contributes to establishing a circular economy for PET.

Keywords: Erwinia sp. LJJL01, PET biodegradation, circular bioeconomy, CRISPR-Cas9, RNA-Seq, plastic upcycling, cis,cis-muconic acid.

Presenting Author: Dushmantha Madushanka Southern Illinois University Carbondale

Presenting Author Biography: - Graduate Research Assistant, Department of Microbiology, Southern Illinois University Carbondale, USA.
- MSc. in Molecular Biology, Microbiology & Biochemistry(reading), Southern Illinois University Carbondale, USA.
- BSc. (Hons) in Agricultural Technology & Management (Specialized in Animal Science), University of Peradeniya, Sri Lanka.
- Working on developing synthetic biological tools (engineered bacteria) for consolidate bioprocessing of plastic.

Authors:

Dushmantha Madushanka Southern Illinois University Carbondale
Lakshika Dissanayake Southern Illinois University Carbondale
Saptarshi Ghosh Southern Illinois University Carbondale
Bhagya Sri Kolitha Southern Illinois University Carbondale
Lahiru N. Jayakody Southern Illinois University Carbondale