Two-step conversion of polyethylene into recombinant proteins using a microbial platform

Journal Article · 16 October 2023 · Microbial Cell Factories

DOI: https://doi.org/10.1186/s12934-023-02220-0 · OSTI ID:2202715

Connor, Alexander; Lamb, Jessica V.; Delferro, Massimiliano; Koffas, Mattheos; Zha, R. Helen

Abstract Background The increasing prevalence of plastic waste combined with the inefficiencies of mechanical recycling has inspired interest in processes that can convert these waste streams into value-added biomaterials. To date, the microbial conversion of plastic substrates into biomaterials has been predominantly limited to polyhydroxyalkanoates production. Expanding the capabilities of these microbial conversion platforms to include a greater diversity of products generated from plastic waste streams can serve to promote the adoption of these technologies at a larger scale and encourage a more sustainable materials economy. Results Herein, we report the development of a new strain of Pseudomonas bacteria capable of converting depolymerized polyethylene into high value bespoke recombinant protein products. Using hexadecane, a proxy for depolymerized polyethylene, as a sole carbon nutrient source, we optimized media compositions that facilitate robust biomass growth above 1 × 10 ⁹  cfu/ml, with results suggesting the benefits of lower hydrocarbon concentrations and the use of NH ₄ Cl as a nitrogen source. We genomically integrated recombinant genes for green fluorescent protein and spider dragline-inspired silk protein, and we showed their expression in Pseudomonas aeruginosa , reaching titers of approximately 10 mg/L when hexadecane was used as the sole carbon source. Lastly, we demonstrated that chemically depolymerized polyethylene, comprised of a mixture of branched and unbranched alkanes, could be converted into silk protein by Pseudomonas aeruginosa at titers of 11.3 ± 1.1 mg/L. Conclusion This work demonstrates a microbial platform for the conversion of a both alkanes and plastic-derived substrates to recombinant, protein-based materials. The findings in this work can serve as a basis for future endeavors seeking to upcycle recalcitrant plastic wastes into value-added recombinant proteins.

• Sponsoring Organization: USDOE
• Grant/Contract Number: AC02-06CH11357
• OSTI ID: 2202715
• Alternate ID(s): OSTI ID: 2469964; OSTI ID: 2477362
• Journal Information: Microbial Cell Factories, Journal Name: Microbial Cell Factories Journal Issue: 1 Vol. 22; ISSN 1475-2859
• Publisher: Springer Science + Business MediaCopyright Statement
• Country of Publication: United Kingdom
• Language: English