Evidence of Plastic Biodegradation Potential by a Fungal Isolate from a Sanitary Landfill in Davao Oriental

Abstract

Plastic pollution, particularly from low-density polyethylene (LDPE), remains a major environmental concern due to its resistance to natural degradation. This study aimed to isolate and characterise microorganisms associated with highly degraded LDPE plastic litter collected from the sanitary landfill in Barangay Anitap, Governor Generoso, Davao Oriental, Philippines, and to evaluate their potential to biodegrade LDPE. Five highly degraded LDPE samples were collected and used for microbial isolation. A total of 10 isolates were recovered, comprising 5 bacterial isolates (BS1–BS5) and 5 fungal isolates (FS1–FS5). Morphological characterization was performed using Nutrient Agar for bacteria and Potato Dextrose Agar for fungi. Screening assays identified fungal isolate FS3 as exhibiting the highest LDPE biodegradation potential. Visible changes in FS3-treated LDPE included surface roughening, thinning, deformation, fragmentation, and extensive fungal colonization. Stereomicroscopic examination revealed dense fungal hyphae attached to and penetrating the plastic surface. Scanning Electron Microscopy (SEM) confirmed significant surface deterioration characterized by cracks, pits, grooves, erosion patterns, and fungal penetration compared with the smooth surface of uninoculated controls. Based on morphological and microscopic characteristics, FS3 was tentatively identified as a Fusarium species, with molecular confirmation through Internal Transcribed Spacer (ITS) sequencing currently ongoing. The findings demonstrate that sanitary landfill environments harbor indigenous microorganisms capable of degrading LDPE. This study provides preliminary evidence supporting the use of landfill-derived fungi as promising biological agents for sustainable plastic waste bioremediation and environmentally friendly waste management strategies.