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A novel bacterial consortium isolated from long-term plastic-contaminated soil exhibits efficient biodegradation of polyvinyl chloride microplastics
Summary
Researchers isolated two novel bacterial strains — Stutzerimonas sp. NH2 and Glutamicibacter nicotinae NH27 — from plastic-contaminated soil and found that their combined consortium degraded PVC microplastics by nearly 27% in weight, with SEM, FTIR, and GC-MS analyses confirming structural breakdown and detection of degradation byproducts.
BACKGROUND: Polyvinyl chloride (PVC) is one of the most widely used synthetic polymers globally, and its continuous accumulation in natural ecosystems has emerged as a critical environmental and public health concern. Recently, microbial degradation has been recognized as an efficient and eco-friendly strategy for mitigating plastic pollution. Despite increasing interest, knowledge of bacteria capable of efficiently degrading PVC microplastics (PVC-MPs) remains limited. This gap highlights the urgency of exploring novel bacterial candidates for effective PVC biodegradation. METHODOLOGY: In this study, soil samples collected from plastic-contaminated sites were utilized to isolate PVC-degrading bacteria using enrichment culture techniques. Bacterial isolates showing potential interaction with PVC were selected and molecularly identified. In addition, their efficacy in degrading PVC-MPs was further confirmed through a combination of analytical and spectroscopic techniques, including scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and gas chromatography-mass spectrometry (GC-MS). RESULTS: The two isolates identified as Stutzerimonas sp. NH2 and Glutamicibacter nicotinae NH27 displayed markedly different PVC biodegradation efficiencies. Strain NH2 achieved a PVC-MPs weight loss of 23.41 ± 0.93%, whereas strain NH27 exhibited a lower degradation efficiency of 5.87 ± 2.16%. Notably, the consortium composed of both strains in equal volumes resulted in a greater PVC-MPs weight loss of 26.84 ± 0.94%, representing a significant increase in PVC-MPs degradation compared with each strain alone (p < 0.05). SEM analysis revealed pronounced morphological alterations on PVC surfaces following bacterial exposure, including cracks, fissures, and grooves. FTIR spectra demonstrated a substantial reduction in the intensities of some functional groups, which could be attributed to PVC degradation. TGA analysis showed a measurable decline in thermal stability, further suggesting chemical structural modifications due to bacterial activity. Additionally, GC-MS analysis detected potential degradation products, providing clear chemical evidence of bacterial-driven PVC degradation. CONCLUSION: This study reports, for the first time, the potential involvement of Stutzerimonas sp. NH2 and Glutamicibacter nicotinae NH27 in the transformation of PVC microplastics. The findings also provide initial insights into the combined activity of these two strains on PVC-MPs, supported by multiple physicochemical analyses. These results contribute to the growing understanding of microbial interactions with PVC microplastics and highlight the potential of these bacteria for future bioremediation studies.