Biodegradability of polystyrene plastics by bacterial isolates from plastic composted waste soil and molecular characterization of plastic degrading bacterial isolates

This study examined the biodegradability of polystyrene (PS) plastics. Soil samples were collected from Oluku Community in Egor Local Government Area, Benin City, Edo State, Nigeria. Heterotrophic bacteria were enumerated and screened for PS degradation potential. Plastics degrading potential of the isolates was determined by Shake Flask method, degradation of PS plastics was determined by analyzing the formulated PS plastic solution for its additive concentration before and after the degradation process using gas chromatograph with mass spectrometry. Identified bacterial isolates were further characterized using the 16S ribosomal RNA gene. The results from all the parameters indicate that there was active utilization of oxygen and other nutrients available in the test system which is an evidence of PS degradation. The pH had values ranging from 6.5 and 7.4. It was observed that the nutrients and the biochemical oxygen demand decreased considerably with time. There was a reduction in the concentration of bisphenol A (BPA) contingents recorded before (37.04 mg/kg) and after (1.19 mg/kg) the degradation process. The bacterial isolates with codes B1 and B3 belonging to Bacillus while B2 belong to Pseudomonas genera were identified. Two isolates had 99% similarity with Bacillus subtilis strain BS3902 and EU047884.1 respectively, while the third isolate had 100% similarity with Pseudomonas aeruginosa strain KAVKOI. This results shows that the strains have the ability and are able to degrade PS plastics.