Biodegradation Potential of LDPE-Degrading Bacteria Isolated from Long-Term Plastic Landfills in Madurai
Low-density polyethylene (LDPE) is widely used but poses serious environmental and health risks when improperly discarded, highlighting the need for effective waste management. Conventional disposal methods are inadequate, making microbial bioremediation a promising and sustainable alternative for plastic degradation. This study aimed to investigate the potential of novel bacterial isolates obtained from long-term plastic waste landfills to degrade LDPE by utilizing polyethylene as their sole carbon source. Partial sequencing of the 16S rRNA gene identified Acinetobacter bereziniae (PD6), Staphylococcus epidermidis (PD9), and Bacillus cereus (PD13) as potential LDPE-degrading bacteria among 14 isolates. The biodegradation of LDPE films was evaluated through weight loss analysis, which revealed no significant variation among the isolates: Acinetobacter bereziniae (0.426%), Staphylococcus epidermidis (0.280%), and Bacillus cereus (0.390%) after 90 days of incubation. Fourier-transform infrared (FTIR) analysis exhibited –CH₂ asymmetric and symmetric stretching bands, accompanied by the emergence of new peaks, while scanning electron microscopy (SEM) confirmed morphological changes in LDPE induced by bacterial biofilm formation. Degradation products identified using GC-MS included n-hexadecanoic acid, 2H-2,4a-methanonaphthalen-8(5H)-one, diethyl phthalate, nonanal, 6-octadecenoic acid (Z), palmitic acid, 9-hexadecenyl ester (Z), oleic acid, bis(2-ethylhexyl) phthalate, decanedioic acid, and bis(2-ethylhexyl) ester. This study highlights the isolation of LDPE-degrading bacterial strains from long-term plastic-contaminated landfill soils, suggesting their adaptive evolution and enhanced capability to utilize polyethylene as their sole carbon source.