Indigenous LDPE degradation bacteria from plastic dumping soils of Thoothukudi coast: isolation, characterization and...

An experiment was conducted to isolate, identify, and characterize the soil bacteria capable of biodegrading untreated Low Density Polyethylene (LDPE) from selected locations of municipal corporation dumping stations in Thoothukudi, Southeast coast of Tamil Nadu, India. A total of 29 distinct bacteria were isolated using Tryptic Soya Agar (TSA) after enrichment of soil samples from the selected sites. Of which, two isolates produced maximum zone of clearance during screening and formed biofilm after 21 days of incubation. The 16 S rRNA sequencing confirmed that the isolates were identified as Paenibacillus timonensis (PX106822) and Cupriavidus nantongensis (PX106762) which resulted in the weight reductions of 3.15% and 1.83% respectively on untreated LDPE after 30 days of incubation. During degradation, the pH of the Mineral Salt Medium (MSM) increased from 6.73 to 8.06 and 8.11 respectively by the two isolates. In the present study, it was observed that the two isolates had increased viable cell count of 7.07 × 10⁸ and 3.83 × 10⁷ CFU/ml respectively with the initial attachment onto the LDPE films followed by biofilm formation, which favoured biodegradation of LDPE. Fourier Transform Infrared (FTIR) spectroscopy and Field Emission Scanning Electron Microscopy (FE-SEM) analysis also confirmed that the two isolates had adhered and attacked on the surface of LDPE film thus serving as evidence for bacterial degradation of LDPE. This study concluded that the isolates had more capability in LDPE biodegradation and will serve as a baseline data for plastic litter management.