Polyvinyl chloride depolymerization and dechlorination by Tenebrio molitor larva-derived bacteria.

Area of Science:

• Environmental Microbiology
• Biotechnology
• Polymer Science

Background:

• Polyvinyl chloride (PVC) is a persistent, ecotoxic plastic causing significant environmental pollution.
• Existing PVC degradation methods are limited, necessitating novel approaches for its remediation.

Purpose of the Study:

• To isolate and characterize microorganisms capable of degrading PVC.
• To elucidate the biochemical pathway and enzymes involved in PVC biodegradation.
• To explore bio-enzymatic strategies for PVC remediation.

Main Methods:

• Isolation of bacterial strains (Acinetobacter sp. PVC-6A, Bacillus sp. PVC-6B) from Tenebrio molitor gut.
• Characterization of PVC degradation using SEM, AFM, ATR-FTIR, and WCA.
• Identification of degradation intermediates and metabolic products via GC-MS.
• Genomic, transcriptomic, and recombinant enzyme analyses to identify key enzymes (CAT, LAC1, LAC2).
• Molecular docking studies to understand enzyme-plastic interactions.

Main Results:

• Bacterial strains demonstrated PVC utilization as a sole carbon source, causing significant weight loss in PVC films.
• A novel biodegradation pathway involving multi-step dechlorination was identified, producing 1-chlorohexadecane and fatty acids.
• Key enzymes, including laccases (LAC1, LAC2) and catalase-peroxidase (CAT), were identified as crucial for PVC degradation.
• Recombinant enzyme treatments confirmed depolymerization and dechlorination, with LAC1 showing high efficacy (13.1% MW reduction, 77% dichlorination).

Conclusions:

• A novel PVC biodegradation pathway mediated by bacterial isolates has been discovered.
• Specific enzymes, particularly laccases, are key players in PVC depolymerization and dechlorination.
• This research provides a foundation for developing effective bio-enzymatic remediation technologies for PVC waste.