Microbial enzymes for plastic degradation: a comprehensive review of current status and emerging trends

The escalating global plastic pollution crisis poses an unprecedented threat to ecosystems and human well-being. Plastic waste that has accumulated over decades remains undegraded and continuously leaches toxic additives and microplastics into the environment. Harnessing the metabolic diversity of microorganisms and their complex enzyme systems can be a sustainable, rapid and cost-effective alternative to conventional plastic waste management. Microbial enzymes that can cleave polymeric chains into valuable biochemicals or monomers opened an encouraging footing to provide a promising foundation for promoting a circular plastic economy. This review outlines the major milestones in enzymatic plastic biodegradation, emphasising the underlying mechanisms, enzyme discovery strategies, and existing challenges and opportunities in this emerging field. Particular focus is given to recent trends in computational, in silico, machine and AI-assisted enzyme discovery. Furthermore, we evaluated current literature on the enzymatic degradation of the most widely used commercial plastics, including polyethylene terephthalate, polyurethane, polyethylene, polystyrene, polypropylene, and polyvinyl chloride. The review ends with a critical analysis of the scope and challenges of the enzymatic degradation of plastics.