1st September 2025 (15 Topics)
1
Sep
Sundarbans Microbes and Plastics
Context:
A study by IISER Kolkata reveals Sundarbans’ microbial communities can degrade plastics but may also carry antibiotic and metal resistance genes.
Microplastics and Nanoplastics:
- Plastics do not biodegrade naturally and fragment into microplastics (<5 mm) and nanoplastics (<1 µm), which persist in ecosystems for decades, accumulate pollutants, and act as carriers of antibiotic resistance genes (ARGs).
Role of Microbes:
- Certain microbes produce enzymes, such as PETase from Ideonellasakaiensis, capable of breaking down plastic polymers like PET. Biodegradation offers a potential natural solution to plastic pollution.
Sundarbans Focus:
- The Sundarbans, the world’s largest mangrove forest spanning India and Bangladesh, receives ~3 billion microplastic particles daily via rivers feeding the Bay of Bengal. Microbial communities in this environment have adapted to high plastic exposure.
Study Methodology:
- IISER Kolkata collected surface water monthly (2020–21) from the Mooriganga estuary, filtered microbial cells, extracted DNA, and performed metagenomic sequencing. Plastic-degrading enzyme (PDE) genes were identified via PlasticDB, while ARGs, metal resistance genes (MRGs), and mobile genetic elements were detected using specialized databases.
Key Findings:
- 838 PDE hits were identified, acting on 17 plastic polymers; 73% targeted synthetic plastics.
- Most abundant PDEs degraded PEG, indicating contamination from biomedical and industrial sources.
- PDE abundance peaked during the monsoon, linked to nutrient and microplastic inflow from inland waters.
AMR and Metal Resistance Co-occurrence:
- Microbes with PDEs often carried ARGs (aminoglycoside resistance) and MRGs (zinc resistance). Co-occurrence network analysis suggests selective pressures from plastic additives, metals, and pollutants drive simultaneous adaptation.
Implications:
- Positive: Microbial plastic degradation offers natural remediation pathways for environmental plastic pollution.
- Negative: Microbes capable of degrading plastics may act as reservoirs of ARGs and MRGs, posing risks to One Health and public health via horizontal gene transfer. Climate change may exacerbate ARG dissemination.
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