Biotechnological Routes for Microplastic Mitigation: Current Challenges and Future Opportunities in the Enzymatic Degradation of Synthetic Textile Waste

The exponential growth of the global textile industry, largely driven by the demand for synthetic polymers such as poly(ethylene terephthalate) (PET), polyamides, and polyurethanes, has led to severe environmental consequences, notably the accumulation of persistent microplastics and solid waste. While conventional mechanical and chemical recycling methods are widely employed, they are often hindered by harsh processing conditions and the deterioration of material properties. Consequently, there is a critical need for sustainable end-of-life management strategies. This review provides a comprehensive analysis of the biodegradability of synthetic textile fibres, with a primary focus on emerging biotechnological and enzymatic recycling approaches. It systematically examines the intrinsic polymer characteristics that govern biodegradation—including molecular orientation, crystallinity, functional groups, and fibre chemistry—as well as extrinsic factors such as textile finishings, yarn twist, polymer blends, and chemical additives. Furthermore, the current landscape of microbial and enzymatic degradation routes is critically assessed, highlighting the specific mechanisms of biocatalysts (e.g., lipases, cutinases, PETase, and MHETase) in depolymerising complex synthetic matrices into recoverable monomers. Finally, this review identifies the existing literature gap between bulk plastic and textile-specific biodegradation, discussing future perspectives. By bridging polymer science and textile engineering, this work underscores the potential of enzymatic recycling to close the loop in synthetic fibre production and advance the transition toward a circular economy.