Biodegradation of Polyethylene by Gordonia Sp. C1 and Bacillus Sp. C2 Isolated from Landfill

Abstract

Polyethylene (PE) is among the most widely utilized petroleum-derived polymers, and its persistent accumulation as plastic waste in the environment has escalated into a pressing global issue requiring immediate attention. Biodegradation presents a promising avenue to the pervasive threat posed by PE plastic waste globally. However, efficient microbial degraders for PE remain limited. In this study, we report the isolation of Gordonia sp. C1 and Bacillus sp. C2 from landfill-derived plastic waste, demonstrating their capability to degrade low molecular weight low-density polyethylene (LDPE) powder and commercial polyethylene (PE) mulch films. LDPE powder and PE mulch film inoculated with C1 and C2 were analyzed by scanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (FTIR), Water contact angle (WCA), 13C-NMR, Thermogravimetric, and High-temperature gel permeation chromatography (HT-GPC). These results indicated that the treated PE films deteriorated with cracks on the PE surfaces, the carbonyl indices of LDPE powder degraded by C1 and C2 for 60 days were 0.36 and 0.26, respectively, and similar biodegradation was also identified from PE film. C1 and C2-mediated PE depolymerization resulted in increased hydrophilicity but decreased weight average molecular weight and thermal stability. The appearance of quaternary carbon and increased C=O groups of PE plastic treated by two strain and their supernatant indicated possible microbial oxidation causing the oxidative breakage of carbon-carbon bonds.  Overall, C1 and C2-mediated polyolefin plastic biodegradation offers an alternative approach for managing PE plastic wastes through possible bio-recycling.

Keywords: Polyethylene, Biodegradation, oxidation, Depolymerization