Isolation and Evaluation of Plastic Degrading Bacterial Species from Municipal Waste Dumping Site

The process of biodegradation involves the breakdown of organic materials by microorganisms, primarily bacteria and fungi. Multiple experiments are conducted to determine optimal conditions for biodegradation in various environments. Proper degradation of biodegradable compounds significantly contributes to the reduction of environmental pollution. This study investigates the microbial degradation of plastic waste, employing soil samples collected from a municipal waste disposal site. Bacterial cultures were prepared in Muller Hinton (MH) medium following serial dilution of the collected samples. After incubation, pure bacterial cultures were isolated, and bacterial morphology was identified via Gram staining. The study identified Gram-positive Bacillus spp. and Gram-negative Pseudomonas and Moraxella spp. as effective plastic-degrading microorganisms. Pure strains of these bacteria were co-incubated with polyethylene discs in nutrient broth for at least one month. Following co-incubation, the polyethylene discs exhibited a 46% reduction in weight, compared to their initial weight, per month. The results indicate that Bacillus spp. exhibit the highest degradation potential among the tested microorganisms, achieving 46% and 44% weight reduction of polyethylene discs monthly, underscoring their effectiveness in plastic breakdown.