Biological and synthetic biology strategies for polystyrene degradation: mechanisms, microbial advances, and circular economy perspectives.

Polystyrene (PS), a petroleum-based synthetic polymer which is extensively used in packaging, insulation, and consumer goods, has emerged as a major environmental pollutant. This report provides a comprehensive overview of recent advances in biological and synthetic biology strategies for novel PS-degrading microorganisms, including bacteria and fungi isolated from unique ecosystems such as insect gut microbiomes and extreme environments. Insects like mealworms and superworms have demonstrated the ability to ingest and degrade PS through symbiotic microbial activity, while fungi such as Aspergillus tubingensis and marine-derived fungi contribute enzymatically to polymer breakdown. Advances in enzymology involving oxidative enzymes like laccases and peroxidases have improved our understanding of PS degradation at the molecular level, supported by innovations in enzyme engineering and immobilization. The paper also examines the biodegradation abilities of bacteria, fungi, and microbes associated with insects and critically analyzes the methods used for degradation assessments, differentiating between genuine biodegradation and mineralization versus surface oxidation, fragmentation, and reduction in polymer weight. Moreover, the advancements in synthetic biology, which include metabolic engineering and engineered microbial consortia, and the biological upcycling of PS intermediates to valuable products, are also covered in light of the circular economy approach.