Converting an Untransformable <i>Vibrio parahaemolyticus</i> Isolate into a Fast Genetic Engineering Platform

The pathogenic bacterium <i>Vibrio parahaemolyticus</i> represents a substantial economic and public health concern; however, elucidating its virulence mechanisms has been significantly impeded by its inherent resistant to genetic manipulation, primarily attributed to sophisticated immune defense systems including restriction-modification (R-M) modules, CRISPR-Cas systems, standalone DNases, and DdmDE systems. Paradoxically, while genetic modification is essential for overcoming these barriers, the very barriers themselves obstruct DNA introduction. Our investigation focused on the <i>V. parahaemolyticus</i> X1 strain, where initial plasmid transformation attempts proved unsuccessful. However, low-efficiency conjugation allowed knockout of defense genes, thereby silencing the host's defense mechanisms. Our findings revealed a standalone DNase, Vpn, as the predominant obstacle to foreign DNA entry in the X1 strain, while a DdmDE system executes elimination of invaded plasmids. Leveraging these insights, we created the <i>V. parahaemolyticus</i> X2 strain via sequential depletion of the Vpn nuclease and the DdmDE system. Capitalizing on the bacterium's exceptional growth rate, characterized by a generation time of approximately 10.5 min, we established a highly efficient molecular cloning platform capable of creating a new plasmid construct within a single day. This work not only presents a strategic framework for genetic manipulation of previously recalcitrant bacterial species but also underscores the potential of fast-growing marine bacteria as promising candidates for next-generation biotechnological applications.