Degradation of polyethylene by three bacteria isolated from coastal beach

Abstract

Polyethylene accumulates due to high production and slow degradation. Microbial degradation offers a promising solution for PE waste treatment. In this study, three bacterial strains, Alloalcanivorax sp. C16-1, Alloalcanivorax sp. C16-2, and Gordonia sp. R-1, were isolated from coastal plastic debris, each capable of utilizing polyethylene powder as the carbon source. After 30 days at 30 °C, low density polyethylene films showed modifications, including bacterial colonization, cracks, and holes as revealed by scanning electron microscopy. The water contact angle decreased, indicating increased hydrophilicity, while attenuated total reflection fourier transform infrared analysis confirmed surface oxidation with the formation of hydroxyl and carbonyl groups. High-temperature gel permeation chromatography showed decreases in the weight-average molecular weight of the films, indicating depolymerization. Nanoscale secondary ion mass spectrometry imaging demonstrated ¹³C assimilation from PE by the three strains at the single-cell level. Genomic analysis revealed that C16–1 and C16-2 were novel Alloalcanivorax species, with genes encoding potential PE-degrading enzymes, such as laccase and alkane hydroxylase, in all three isolates. These strains are widely distributed in marine environments, particularly in plastic accumulation hotspots, offering promising candidates for PE biodegradation research.