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Engineered Vibrio natriegens as a living biocatalyst for in-situ biodegradation of microplastics in seawater
Summary
Researchers engineered the fast-growing marine bacterium Vibrio natriegens to display PETase enzymes on its outer membrane, creating a living biocatalyst that degrades PET microplastics directly in seawater conditions, outperforming comparable E. coli-based systems in both growth rate and hydrolytic activity. This halophilic whole-cell approach addresses a key gap in bioremediation — most PETase studies use freshwater organisms that cannot survive the salinity of marine environments where plastic pollution is most severe.
Marine microplastic pollution, particularly from polyethylene terephthalate (PET), presents urgent ecological challenges. Although polyethylene terephthalate hydrolase (PETase) offers a promising avenue, its implementation in saline environments remains limited by host incompatibility and enzyme instability. Here, we present a halophilic whole-cell system that integrates PETase into the fast-growing marine bacterium Vibrio natriegens (Vn). To enhance catalytic robustness and substrate accessibility, we engineered Vn to display PETase on its outer membrane, generating a promising living biocatalyst (Vn-PETase). Under simulated marine conditions (3.5 % NaCl at 30 °C), Vn-PETase demonstrated significantly faster growth (μ = 0.420 h) and higher hydrolytic activity (96.6 % conversion of a model substrate within 6 h) compared with E. coli-based counterparts (μ = 0.018 h and 39.3 % conversion). Building upon this platform, we developed Vn-FastPETase, which displays an engineered PETase variant with enhanced catalytic performance, resulting in markedly improved PET hydrolysis. Vn-FastPETase achieved efficient in-situ depolymerization of PET micro- and nano-particles to mono-(2-hydroxyethyl) terephthalate (MHET) and terephthalic acid (TPA) during cultivation in artificial seawater. This study establishes Vn as a marine-compatible host for in-situ PET biodegradation and demonstrates a proof-of-concept strategy toward developing living biocatalysts for mitigating plastic pollution in ocean environments.