Isolation and characterization of marine microorganisms capable of degrading plastics

The escalating crisis of global plastic pollution has prompted increasing efforts toward the identification of plastic-degrading microorganisms as environmentally sustainable solutions. Despite marine ecosystems being the most affected, the systematic exploration of culturable plastic-degrading microorganisms remains critically underexplored. Here, we established the largest marine microbial repository for plastic biodegradation, comprising 1,377 bacterial and 202 fungal strains isolated through optimized culture strategies targeting 13 plastic polymers. Methodological benchmarking revealed selective enrichment combined with carbon-supplemented dual-layer plating as the most effective isolation approach. Plastic substrate specificity drove phylogenetic divergence among degraders, with <i>Bacillus altitudinis</i> emerging as the dominant polyurethane (PU)-degrading lineage. Comprehensive functional screening identified five polyethylene terephthalate (PET)-degrading strains (<i>Cerrena</i> sp., <i>Hortaea werneckii</i>, <i>Streptomyces badius</i>, <i>Streptomyces cinereoruber</i>, <i>Cladosporium</i> sp.), five polyethylene (PE) degraders (<i>Qipengyuania citrea</i>, <i>Gordonia mangrovi</i>, <i>Penicillium oxalicum</i>, <i>Penicillium aethiopicum</i>, <i>Streptomyces pluricolorescens</i>), and 130 polyester-based PU-degrading strains spanning <i>Bacillus</i>, <i>Psychrobacter</i>, <i>Priestia</i>, and <i>Cladosporium</i> genera. This work provides both a foundational microbial resource for plastic biodegradation and establishes a methodological framework for the targeted isolation of plastic-degrading pure cultures.IMPORTANCEMarine plastic pollution presents a significant global challenge, with millions of tons entering the oceans each year, threatening marine life and ecosystem integrity. Microbial degradation offers a promising, sustainable solution by leveraging natural biological processes to break down plastics. This study makes a substantial contribution to the field by systematically examining 13 plastic types and establishing the largest known marine microbial resource for plastic degradation. Over 1,500 bacterial and fungal strains were isolated from diverse marine environments through optimized culturing strategies. Key microorganisms capable of degrading commonly used plastics-such as polyethylene terephthalate (bottles), polyurethane (foams), and polyethylene (packaging)-were identified. These findings lay a critical foundation for the development of microbial-based technologies to mitigate plastic pollution, offering scalable and environmentally friendly solutions to protect marine ecosystems.