Identification and characterization of low density polyethylene-degrading bacteria isolated from soils of waste disposal sites

Abstract

The current study focused on an environment friendly method for degradation of Low Density Polyethylene (LDPE) using bacteria. A total of 36 bacterial strains were isolated from waste disposal sites in which six strains showed potential biodegradation activities. In this study, we reported 2 new strains i.e. Bacillus siamensis and Bacillus wiedmannii for LDPE degradation. The percent weight loss of LDPE films for isolates was; B. siamensis (8.46 +/- 0.3%), B. cereus (6.33 +/- 0.2%), B. wiedmannii (5.39 +/- 0.3%), B. subtilis (3.75 +/- 0.1%), P. aeruginosa (1.15 +/- 0.1%) and A. iwoffii (0.76 +/- 0.1%) after 90 d of incubation. The LDPE films showed slight surface disruption as observed in Field Emission Scanning Electron Microscopy (FE-SEM) and Fourier Transform Infrared Spectroscopy (FTIR) showed formation of typical carbonyl peaks which were markedly reduced after incubation as measured by carbonyl index. The X-Ray Diffraction (XRD) analysis presented an increase in percent crystallinity and there was no apparent change in total carbon percentage. Different genes responsible for degradation of LDPE like Laccase (167 bp), Alk1 (330 bp) and Alk2 (185 bp) were identified in bacterial isolates and further sequenced. The low degradation values in this study indicate that LDPE degradation is a slow, continuous and time dependent process.