Microbial and Enzymatic Degradation of Polylactic Acid (PLA) and Related Polyesters: Molecular Mechanisms, Marine Environmental Dynamics, and Biotechnological Innovations

Polylactic acid (PLA) is one of the most commercially used biodegradable polymers produced from renewable biomass sources. Even though PLA can be composted under controlled industrial conditions. Still, it persists in marine and natural environments, continues to cause environmental concern. This review examines the microbial and enzymatic pathways responsible for the degradation of PLA and related polyester, focusing on the structural biology of polyester hydrolases, thermophilic depolymerases, marine microbial ecology, degradation kinetics, and strategies in recombinant enzyme development. Advanced analytical techniques, metagenomic screening platforms, and protein engineering approaches are examined to bridge laboratory insights with real-world biodegradation outcomes. The review synthesizes findings from over fifteen peer‑reviewed sources and identifies future directions for sustainable polymer management.