Rethinking plastics through microbial biodegradation and circular economy innovation – A review

The global plastic crisis has evolved into a complex socio-environmental emergency, driven by unsustainable production patterns, weak waste management infrastructure, and the ecological persistence of synthetic polymers. Microplastics and nanoplastics now permeate terrestrial and aquatic ecosystems, posing chemical and biological risks across trophic levels. This review presents a comprehensive analysis of emerging biotechnological and circular strategies for plastic sustainability, with a particular focus on microbial ecosystems and enzymatic innovation. Abiotic and biotic degradation pathways are examined, detailing how environmental factors such as photodegradation, thermo-oxidation, and hydrolysis facilitate microbial colonization and polymer fragmentation. Key microbial taxa—including bacteria, fungi, actinomycetes, and algae—are evaluated for their roles in enzymatic depolymerization, while consortia-based models demonstrate synergistic potential in degrading complex plastic mixtures. Enzymes such as polyethylene terephthalate hydrolase, mono(2-hydroxyethyl) terephthalate hydrolase, laccases, and peroxidases are discussed alongside computational and synthetic biology approaches for enhancing their catalytic performance. The review further integrates these biological innovations into broader systems-based frameworks, exploring hybrid degradation technologies, bio-based valorization, and alignment with circular economy principles. Policy landscapes and public engagement mechanisms are assessed, along with international efforts to harmonize action through multilateral frameworks and sustainable development goals. Critical gaps in scalability, regulatory coherence, and lifecycle optimization are identified, and a roadmap is proposed for transitioning from linear to bio-integrated plastic economies. Through interdisciplinary synthesis, this review positions microbial and enzymatic biodegradation not as isolated tools, but as keystones in a globally coordinated response to plastic pollution and environmental resilience.