Biodegradation of poly(ethylene terephthalate): Mechanistic insights, advances, and future innovative strategies

Globally, poly(ethylene terephthalate) (PET) is the most utilized class of thermoplastic single-use polyesters, accumulating in ecosystems and aggravating ecological pollution. There are several physicochemical and thermal treatments available that are energy intensive and further lead to the generation of secondary pollutants, toxic byproducts, and lethal gases. Biological method is an up-rising technique that has a unanimous potential for PET degradation recycling and monomer recovery owing to the presence of hydrolysable ester bonds. However, enzymatic PET degradation still has numerous limitations, such as slow processing times and low degradation rates, which limit competing with upscaling routes to achieve industrial levels. In the present review, PET degradation via microbial and enzymatic pathways is discussed, along with mechanisms and parameters that influence biodegradation. Subsequently, numerous innovative strategies are discussed, including enzyme engineering and modification via mutagenesis, enzyme cooperativity, multiple enzyme utilization, enzyme-substrate interactions, expanded substrate specificity, and improvement of reaction conditions. Lastly, the review concludes with the future perspectives in the biodegradation and subsequent biotransformation of PET wastes to produce value-added compounds with the involvement of computational biology and automation approach including Industry 4.0, deep learning, and IoT.