Microbial Upcycling of Polyethylene into Recombinant Proteins

Abstract

Abstract Herein, we report the development of a new strain of Pseudomonas bacteria capable of upcycling deconstructed 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, with results suggesting the benefits of lower hydrocarbon concentrations and the use of NH4Cl 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 upcycled into silk protein by Pseudomonas aeruginosa at titers of 11.3 ± 1.1 mg/L. Thus, this work establishes a versatile microbial platform for valorizing recalcitrant plastic waste.