Linear low-density polyethylene plastic degradation by Bacillus cereus, Achromobacter insolitus, and Bacillus stercoris isolated from Kumaraswamy Lake, India

The study aimed to identify LLDPE degrading microorganisms from Kumaraswamy Lake and examine their biodegradation activity over a 60 day period. Out of 15 bacterial isolates, Bacillus cereus , Achromobacter insolitus , and Bacillus stercoris were selected for detailed investigation based on their superior LLDPE film degradation ability after 20 days of exposure. After 60 days, Bacillus cereus IB2.5 exhibited the fastest plastic degradation at 10.84 ± 0.39%, followed by Achromobacter insolitus IBA.6 with 8.25 ± 0.19% and Bacillus stercoris IB2.4 with 6.27 ± 0.29%. FESEM analysis shows that untreated LLDPE remains smooth and uniform, while Bacillus cereus -treated LLDPE exhibits the most degradation, with pits, bioerosion, roughness, cracks, and grooves. EDX analysis reveals significant changes in LLDPE composition after bacterial degradation, with carbon decreasing from 94.56% (control) to 86.96% ( Bacillus cereus ) and 87.19% ( Achromobacter insolitus ), while oxygen increased from 3.52% to 10.99% and 10.75%, respectively. The bacteria-treated LLDPE ATR-FTIR spectrum exhibits significant changes compared to the control LLDPE, indicating biodegradation and structural modifications, including C C stretching and the presence of amide groups, as well as the formation of hydroxyl (-OH) and carbonyl (C O) groups, suggesting oxidation and polymer degradation. Enhanced bacterial growth in LLDPE-treated cultures indicated the utilization of LLDPE as a carbon source. The findings highlight the potential of indigenous freshwater bacteria in the biodegradation of LLDPE plastics and provide a sustainable biological approach for mitigating plastic pollution. Furthermore, the study supports recent evidence that microbial degradation of LLDPE can reduce its ecological toxicity, emphasizing the environmental relevance of biodegradation based remediation strategies.