Value recovery from plastic wastes via biodegradation of low-density polyethylene by Aspergillus, Proteus and Serratia species

Abstract

Daily production and release of enormous quantities of plastic wastes into the environment are on the increase. Being recalcitrant to degradation, they are known to constitute a waste burden to cities and municipalities as they accumulate in the different environmental media. The search of remedies for plastic accumulation and pollution of our Environment and the possibility of recovering value from plastic wastes via the biodegradation potentials of indigenous microorganisms prompted this research work. Using standard microbiological techniques, 3 microorganisms, Aspergillus sydowii, Proteus vulgaris and Serratia marcescens were isolated from different dumpsites in Owerri West Local Government Areas (LGA), Imo State, Nigeria. Incubation of shredded and ground low-density polyethylene sachets with the test isolates was done in mineral salts vitamin medium(MSVM) for 60 days, and their ability to degrade the polyethylene was evaluated using visible spectrophotometer (OD600), fourier transform infra-red spectroscopy (FTIR) and gas chromatography-mass spectrometry (GC-MS) techniques. Results obtained indicated increase in optical densities (OD600) in the media inoculated with the test isolates: A. sydowii, (0.12 – 0.80), P.vulgaris (0.11-0.71) and S.marcescens (0.10-0.69), while the control sample without microbial inoculation remained unchanged. Similarly, the number of functional groups and compounds eluted was low in the control sample (8 and 11), but increased and differed in the three organisms: A.sydowii (11 and 44), P. vulgaris (14 and 48) and S. marcescens (12 and 38) respectively, indicating that the organisms exhibited varying degrees of competence in polyethylene degradation. It was concluded that Indigenous microorganisms were able to degrade low-density polyethylene, and that biodegradation of polyethylene resulted in the release of a variety of chemical compounds with great potentials applicability in various industries. The reactions involved in this biodegradation could be further studied and optimized as a waste-to-wealth strategy towards sustainable environmental management.