Adv Biotechnol (Singap). 2026 Apr 15;4(2):14. doi: 10.1007/s44307-026-00104-z.
ABSTRACT
Enzymatic depolymerization of polyethylene terephthalate (PET), the world’s most widely used polyester, in seawater at ambient temperature offers a promising and energy-efficient route for freshwater-free plastic recycling. While a number of PET hydrolases have been reported in recent years, their potential under saline conditions remains largely unexplored. Here, we screened eight enzymes in artificial seawater at 30 °C and engineered the most active one, IsPETase, using a semi-rational strategy focused on rigidifying flexible sites. The resulting variant M8 showed simultaneous enhancementsin thermostability (ΔTm = + 27.3 °C), activity (1.14-fold increase) and soluble expression yield (14.3-fold increase). The overall depolymerization efficiency of M8 surpassed that of the thermostable benchmark enzymes DuraPETase and LCC-ICCG by 32.2- and 10.4-fold, respectively. Notably, M8 achieved continuous and efficient depolymerization of 15% (w/v) PET powder in natural seawater at 37 °C, yielding monomers at a rate of 15.4 mM/day, a concentration sufficient to support downstream bacterial assimilation. This work provides an efficient enzymatic platform and paves the way for fully integrated, seawater-based plastic bioconversion processes.
PMID:41984279 | DOI:10.1007/s44307-026-00104-z