Polyethylene Degradation by a Rhodococcous Strain Isolated from Naturally Weathered Plastic Waste Enrichment

Abstract

Polyethylene (PE) is the most widely produced synthetic polymer and the most abundant plastic waste worldwide due to its recalcitrance to biodegradation and low recycle rate. Microbial degradation of PE has been reported, but the underlying mechanisms are poorly understood. Here, we isolated a Rhodococcus strain A34 from 609 day enriched cultures derived from naturally weathered plastic waste and identified the potential key PE degradation enzymes. After 30 days incubation with A34, 1% weight loss was achieved. Decreased PE molecular weight, appearance of C–O and CO on PE, palmitic acid in the culture supernatant, and pits on the PE surface were observed. Proteomics analysis identified multiple key PE oxidation and depolymerization enzymes including one multicopper oxidase, one lipase, six esterase, and a few lipid transporters. Network analysis of proteomics data demonstrated the close relationships between PE degradation and metabolisms of phenylacetate, amino acids, secondary metabolites, and tricarboxylic acid cycles. The metabolic roadmap generated here provides critical insights for optimization of plastic degradation condition and assembly of artificial microbial communities for efficient plastic degradation.

Multistep Enzymatic Low-density Polyethylene Degradation via Phenylalanine Monooxygenase and Isocitrate Lyase in Pseudomonas aeruginosa

“…Transporter proteins, such as long-chain fatty acid-transporting porins, facilitate the transport of hydrophobic intermediate molecules into cells, whereas oxidoreductases play a crucial role in plastic degradation 13,22,31 . Among the 247 genes that were upregulated simultaneously in both the transcriptome and proteome, the majority were associated with transporter functions, acyl-CoA dehydrogenase (involved in lipid metabolism), and largely uncharacterized hypothetical proteins (Table S9).…”