Microbial and enzymatic degradation of plastics: Opportunities and constraints for plastic waste remediation

The rapid increase in global plastic production over the past century has led to a severe environmental crisis, characterized by widespread contamination of terrestrial, freshwater, and marine ecosystems. Recently, microbial and enzymatic degradation has emerged as a promising alternative to conventional plastic waste management owing to its environmentally friendly nature and mild operational conditions. However, this approach still faces several critical challenges, including overinterpretation of degradation evidence, incomplete mechanistic understanding, and limited validation of true biodegradation. This review adopts a critical perspective to evaluate whether reported biodegradation is experimentally reliable and biologically meaningful. We synthesize recent advances in the biodegradation of both hydrolysable and non-hydrolysable plastics polymers, with specific emphasis on polymer-specific degradation mechanisms, analytical limitations, and methodological strategies for distinguishing genuine degradation from apparent surface deterioration. We further discuss emerging issues that determine practical relevance, including effects of contaminants in real plastic waste and divergent biodegradation behaviors of macroplastics and microplastics. By integrating mechanistic insights with rigorous evaluation criteria, this review provides a framework for advancing plastic biodegradation research from descriptive screening toward reliable validation and practical application.