Enzyme-Assisted Biodegradation of Micro-Nanoplastics: Advances and Future Outlook on the Management of Plastic Pollution

Plastics are non-degradable synthetic polymers used worldwide for their felicitous properties. The accumulation of plastic debris in the environment is becoming increasingly prominent, and the conventional disposal methods are off the mark. The abiotic environmental factors degrade the plastics partially, and some anthropogenic activities are responsible for the production of microplastics (MPs) (<5 mm), which, in turn, are converted into nanoplastics (NPs) (<1 mm). These plastics remain to be a huge threat to the environment, ecosystem and human health. This has been accentuated in recent years, and several eco-friendly methods were explored to address plastic pollution. The discovery of PETase, an enzyme that degrades PET, from Ideonella sakaiensis is an aspiration for the enzyme-assisted biodegradation of plastics, which is a promising green approach for environmental sustainability and circular economy. However, scarcely identified plastic-biodegrading enzymes, slow biodegradation and low stability of enzymes hinder the real-time applications. This review deals with the availability and enzymatic biodegradation of plastics and the employment of different emerging approaches such as gene editing, nanotechnology, synthetic and computational biology to modify and design the enzymes for effective biocatalysis. In addition, the knowledge gap between discovery and application and the necessity of interdisciplinary knowledge for the biotransformation of plastics into valued-added products are discussed.