海洋由来微生物によるポリエチレンマイクロプラスチックの分解メカニズムの解明：酵素経路と中間体の同定

The accumulation of polyethylene microplastics (PE-MPs) in marine and coastal environments, particularly mangrove ecosystems, poses significant environmental challenges. To address this, we investigated the bioremediation potential of two bacterial strains, Lysobacter sp. (MAS-1) and Nitratireductor kimnyeongensis (MAS-2), isolated from biofilm-coated PE-film in a Thailand mangrove area. Microbial community analysis revealed a shift toward Proteobacteria (47-92 %) and Actinomycetota (5-41 %) in PE-MP-enriched consortia, indicating niche specialization. Both strains exhibited significant degradation, with MAS-1 achieving 35.4 ± 1.2 % and MAS-2 achieving 23.04 ± 0.8 % weight loss of PE-MPs within 30-days. Biofilm assays confirmed substantial microbial adhesion on PE-MPs, and SEM imaging revealed surface pitting and cracking, indicative of microbial colonization and polymer breakdown. While FT-IR analyses showed oxidative modifications including carbonyl (CO), hydroxyl (-OH), and ether (C-O) groups, enhancing PE surface hydrophilicity. LC-MS/MS identified organic acids and nitrogen- and sulfur-rich compounds in a liquid medium, with in silico BioTransformer 3.0 analysis predicting strain-specific pathways like sulfur oxidation for MAS-1 and dehalogenation of MAS-2. These findings establish the bioremediation potential of mangrove-derived microbes and highlight the strains' distinct metabolic roles in PE-MP degradation.