Integrative frameworks for plastic biodegradation in insect-microbiome systems: mechanistic insights, emerging...

Plastic pollution remains a major global environmental challenge due to the persistence and recalcitrance of synthetic polymers, particularly polyolefins such as polyethylene and polypropylene. Conventional management strategies, including landfilling, incineration, and chemical recycling, are energy-intensive and often fail to achieve complete degradation. Biological approaches offer a promising alternative, yet microbial systems alone are frequently limited by low degradation efficiency, incomplete mineralization, and challenges in scalability. In this context, insect-microbiome systems have emerged as integrated biological platforms in which host physiology and gut microbial communities interact to facilitate polymer transformation. This review synthesizes current knowledge on plastic degradation in insect larvae, with a focus on mechanistic insights into host-microbe interactions. Evidence suggests a multi-step process involving mechanical fragmentation, oxidative modification of polymer chains, microbial depolymerization, and metabolic processing of intermediates. However, the relative contributions of host-derived enzymes and gut microbiota, as well as the extent of true biodegradation versus partial transformation, remain incompletely resolved. Advances in multi-omics approaches have provided important insights into these systems by linking physicochemical changes in polymers to underlying molecular and metabolic processes. At the same time, these data are largely correlative, and direct experimental validation of specific enzymatic roles remains limited. Building on these insights, emerging enzyme engineering and synthetic biology strategies aim to replicate the coordinated, multi-step processes observed in insect systems for improved degradation efficiency. This review highlights insect-microbiome systems as valuable models for understanding complex biodegradation mechanisms and guiding the development of integrated, enzyme-based strategies for sustainable plastic waste management.