Isolation of a novel microplastic-degrading bacterial strain: a promising agent for low-density polyethylene remediation

This study investigates the biodegradation capabilities of two bacterial strains, Rhodococcus erythropolis and Paenarthrobacter nitroguajacolicus, identifying P. nitroguajacolicus as a novel candidate for its ability to degrade low-density polyethylene (LDPE), a major contributor to plastic pollution. Both strains were isolated from plastic-contaminated environments and cultivated in laboratory conditions with LDPE as the sole carbon source. Viable cell count measurements revealed that P. nitroguajacolicus achieved a peak bacterial count of approximately 2 × 106 CFU/mL, with intermittent increases observed over the 45-day incubation period. In comparison, R. erythropolis exhibited a more stable trend, with a peak count of 5 × 105 CFU/mL. These findings highlight the superior growth potential of P. nitroguajacolicus on LDPE. ATP measurements indicated significant metabolic activity, with P. nitroguajacolicus showing higher vitality with an RLU value of 135 compared to R. erythropolis, which recorded an RLU of 96. This supports the assertion that Pn is metabolically more active in degrading LDPE. Additionally, structural and chemical changes in LDPE were confirmed using Scanning Electron Microscopy (SEM), Nuclear Magnetic Resonance (NMR), and Fourier-transform infrared (FTIR) spectroscopy. R. erythropolis demonstrated more pronounced surface degradation of LDPE, while P. nitroguajacolicus exhibited higher metabolic activity, emphasizing their complementary roles in biodegradation. This study highlights the potential of these bacteria in sustainable bioremediation strategies for mitigating plastic pollution, with P. nitroguajacolicus emerging as a novel and particularly promising candidate due to its degradative capacity for LDPE.