Biodegradation of low-density polyethylene by Paenarthrobacter nicotinovorans JPEA-9 and its putative degradation...

Polyethylene is one of the most extensively used plastics worldwide. It is highly resistant to biodegradation, and its accumulation in the environment has become a major global concern. The aim of this study was to isolate an low-density polyethylene (LDPE)-degrading strain and investigate its putative degradation mechanism. The Gram-positive strain, Paenrthrobacter nicotinovorans JPEA-9, which was isolated from plastic waste in a landfill site, degraded LDPE powder and film, causing weight losses of 14.4 ± 0.1% after 20 days and 7.0 ± 0.8% after 120 days, respectively. Among the reported LDPE-degrading strains within the genus Paenarthrobacter, JPEA-9 showed the highest degradation activity. The degradation of LDPE film was characterized using water contact angle measurement, scanning electron microscopy, and Fourier transform infrared spectroscopy, while the degradation products were analyzed using liquid chromatography-tandem mass spectrometry. During the 120-day incubation, the LDPE film showed increased surface roughness, enhanced absorption bands associated with oxygen-containing functional groups and reduced surface hydrophobicity. C₃₅ and C₃₇ fatty acids were identified as degradation products. Genome analysis further revealed four candidate genes encoding cytochrome P450, alcohol dehydrogenase, aldehyde dehydrogenase, and esterase that may be associated with LDPE biodegradation. Based on the combined results of biodegradation characterization and whole-genome analysis, a putative multi-enzyme degradation mechanism was proposed. This study provides the first genome-level insight into LDPE biodegradation by Paenarthrobacter nicotinovorans and broadens the known diversity of LDPE-degrading bacteria, thereby laying a foundation for future studies on microbial bioremediation of plastics.