A marine bacterial strain with polyurethane-degrading activity, a potential for plastic waste control in the oceans

Plastic pollution represents a significant global challenge, and diverse strategies, including microbial degradation, are needed to address it. This comprehensive study investigated the potential of the novel deep-sea bacterium Stutzerimonas frequens GOM2 to degrade polyurethane (PU), focusing on its ecological safety, including pathogenicity and survival in zebrafish embryo population controls, and the potential for plastic recycling. The marine isolate exhibited the capacity to grow and present clearance halos in functional screenings using two types of commercial water-based dispersions of polyester-PU (Impranil and Polycrylic). The biodegradation of the PU Impranil by the GOM2 strain was subsequently assessed in marine microcosms by monitoring bacterial growth and metabolic activity over time. Physicochemical analyses (including GPC, FTIR, and GC–MS) were used to monitor polymer breakdown by molecular weight loss, changes in functional groups, the disappearance of toxic PU precursors and the appearance of secondary metabolites. GC–MS analysis identified several metabolic intermediates, including plastic and bioplastic precursors, and compounds with potential pharmaceutical applications. Genomic analyses revealed genes encoding enzymes associated with plastic degradation, and the bacterium was found to be nonpathogenic. This strain successfully reversed the embryonic lethality of Impranil in zebrafish via biodegradation of PU, demonstrating the potential for this strain to reduce the toxicity of this plastic. Taken together, our results highlight the potential applicability of S. frequens GOM2 in future biotechnological applications that have significant implications for the blue economy. • Mining marine bacteria adapted to environments where hydrocarbons are ubiquitous enables a more effective search for plastic-degrading microorganisms. • Stutzerimonas frequens GOM2, a newly identified marine bacterium from the Gulf of Mexico, can degrade PU and reduce Impranil-related mortality in zebrafish embryos. • To address the plastic pollution problem from a blue economy perspective, plastic degradation research must adopt a broader approach, incorporating environmental safety assessments such as zebrafish survival assays as complementary tools, in addition to demonstrating polymer degradation and the production of economically valuable compounds. • Continued investigation of PU recycling via the isolation of microbial enzymes involved in robust mechanisms of degradation remains indispensable.