Recent advances and challenges in the biotechnological upcycling of plastic wastes for constructing a circular bioeconomy

•Plastic upcycling is a significant strategy for the remediation of plastic wastes.•Bio-based plastic upcycling includes biodegradation and microbial valorization.•The discovery of PETase has shifted the research paradigm toward plastic upcycling.•The microbial valorization of plastic monomers into useful products is discussed.•Plastic upcycling will contribute to the construction of a circular bioeconomy.