Biodegradation of Plastics by Bacteria Isolated from Freshwater Habitat in Kaduna Metropolis, Nigeria.

The extensive use of plastics poses severe environmental threats to both terrestrial and aquatic ecosystems, as they are poorly degradable and accumulate in large volumes after disposal. While most plastic-related research has focused on marine environments, few studies focused and examined freshwater systems. This study aimed to isolate and characterize bacteria colonizing plastics in freshwater environments and assess their plastic biodegradation potential. Water samples were collected from the Kaduna River, Nigeria. Physicochemical parameters were determined using standard methods, and bacteria colonizing plastics were isolated using standard spread plate techniques. Low-density polyethylene (LDPE) and high-density polyethylene (HDPE) samples were obtained from commercial sources and use as plastic sources. Mineral salt broth was used to screen bacterial isolates for polyethylene degradation ability, with growth assessed visually after 16 days by comparing turbidity levels with control samples. The physicochemical parameters of freshwater samples were within acceptable limits established by WHO and NSDWQ. Five bacterial genera were identified from plastic-associated isolates: Bacillus, Staphylococcus, Streptococcus, Micrococcus, and Proteus. Staphylococcus aureus showed the highest occurrence (39.29%), followed by Bacillus species (21.43%), Micrococcus species (17.86%), Streptococcus species (14.28%), and Proteus species (7.14%). No significant differences were observed between bacterial isolates in their biodegradation potential for LDPE and HDPE plastics (p > 0.05). However, turbidity measurements for LDPE degradation varied significantly across treatment days (p < 0.05), as did pH and turbidity values for HDPE degradation over the treatment period (p < 0.05). The results contribute to understanding microbial plastic degradation in understudied freshwater ecosystems and suggest promising avenues for bioremediation applications. These findings demonstrate that bacteria in freshwater environments possess distinct metabolic capabilities that offer potential for biodegradation of plastics and other pollutants in aquatic systems.