Effect of Used Engine Oil and UV-Thermal Pretreatments on Biodegradation of Low-Density Polyethylene by <em>Lysinibacillus fusiformis

Abstract

The present study focused on the impact of Used Engine Oil (UEO) and abiotic pretreatments by ultraviolet (UV) radiation and thermal treatment at 70°C for 144 h on the potential of Lysinibacillus fusiformis TPB isolated from hydrocarbon contaminated soil for the biodegradation of low-density polyethylene (LDPE) in mineral salt medium at 30°C and 150 rpm for 30 days. The isolated L. fusiformis TPB degraded 9.51% of LPDE films without any treatment and used as the sole carbon source for biomass production. The supplementation of used engine oil (0.5% v/v) enhanced biodegradation of untreated LDPE films to 11.96% comparable to a non-ionic surfactant Tween 80. The abiotic pretreatments had also facilitated metabolism of LDPE by L. fusiformis TPB. The biodegradation of UV treated LDPE by L. fusiformis TPB was 13.78% and was significantly higher than thermally treated LDPE with 12.89% biodegradation. The Fourier Transform Infrared spectrum revealed structural and morphological changes in the LDPE films by abiotic pretreatments and were associated with addition of carbonyl groups and change in double bond index. The Scanning Electron Microscopy analysis of LDPE films from UEO and UV-thermal pretreated LDPE supplemented mineral salt media confirmed the improved bacterial colonization and biofilm formation. The isolated L. fusiformis TPB had LDPE degradation potential and biodegradation had improved by UEO supplementation and UV-thermal pretreatments.