Cooperative enzymatic depolymerization of poly(lactic acid) nonwoven fabrics using a newly identified cutinase Cr14CLE and proteinase K

Abstract

The development of efficient enzymatic strategies for poly(lactic acid) (PLA) recycling remains limited by the insufficient catalytic performance of single enzymes and the lack of mechanistic understanding of multi-enzyme cooperation. In this study, a newly screened cutinase, Cr14CLE, was characterized and, for the first time, systematically combined with proteinase K to investigate their cooperative degradation of PLA nonwoven fabric. Comprehensive structural and physicochemical analyses, including GPC, FT-IR, XRD, SEM, and thermal analysis, were employed to track the dynamic evolution of PLA during enzymatic hydrolysis. Notably, the dual-enzyme system exhibited a significantly enhanced degradation efficiency, achieving 71.3% degradation within 12 h at a total enzyme loading of 300 U, which exceeded the theoretical additive effects of individual enzymes. This enhancement was quantitatively attributed to a complementary catalytic interplay between Cr14CLE and proteinase K. Importantly, this study reveals a previously uncharacterized multistage degradation pathway, involving initial activation of less ordered regions, followed by destabilization of crystalline domains and eventual fiber fragmentation. These findings not only introduce Cr14CLE as a promising biocatalyst but also establish a mechanistic framework for designing synergistic enzymatic systems for efficient PLA biorecycling.