Biodegradation of plastic materials obtained from solid waste dumpsites in Nigeria, using native bacterial strains

Plastic packaging materials constitute a major potential environmental pollutant due to their slow degradation rates. This study aimed to isolate the plastic-degrading bacteria from the solid waste dumpsites of Abuja, Nigeria. Soil samples (n= 72) and plastic materials (bottles and bags) were collected from the dumpsites using soil augers and manual picking, respectively. Bacteriological analysis of the soil samples revealed the recovery of a total of 54 bacterial isolates, which were distributed among the genera of; Proteus sp. (33.3 %), Providencia sp. (29.63 %), Pseudomonas sp. (16.67 %), Bacillus sp. (9.26 %), Micrococcus sp. (5.56 %), Escherichia coli (1.85 %), Enterobacter sp. (1.85 %), and Serratia sp. (1.85 %). The bacterial isolates were inoculated into a series of shake flasks containing nutrient broth and pre-sterilized strips (1×1 cm) of plastic bags (0.05-0.0514 g) and plastic bottles (0.05-0.0529 g), and then incubated at 30 o C for 60 d to monitor their biodegradation using the weight loss method. The strips of bottles (0.58-49.00 %) were more susceptible to biodegradation than the plastic bags (0.78-15.40 %) after 60 d of incubation. The results demonstrated that about 6 of the bacterial isolates belong to the two genera of Proteus sp. and Providencia spp., and were considered the best bio-degraders. Molecular characterization of these potent isolates has identified them as Proteus mirabilis strain PPB3 (49.00 %), Proteus mirabilis strain UPMSD3 (32.07 %), Proteus mirabilis strain HH133 (20.41 %), Proteus mirabilis strain SSBIKEN (15.40 %), Providencia vermicola strain M4 (14.96 %), and Providencia vermicola strain 11 (12.20 %). These strains could be considered as potential biodegradation agents for the plastic materials that are prevalent in dumpsites.