A Fluorogenic Biosensor for Direct Detection of Vibrio vulnificus, a Climate Change Biomarker.

Vibrio vulnificus, a marine pathogen and climate change biomarker, poses serious risks to human and animal health through seafood consumption and seawater exposure. Rapid detection methods are urgently needed for both vibriosis diagnosis and surveillance in warming coastal waters. We report a fluorogenic biosensor based on nanoporous anodic alumina loaded with rhodamine B and capped with an oligonucleotide probe targeting a unique sequence of the vvhA cytolysin gene, specific to V. vulnificus. In the presence of the target DNA, the probe is displaced, pores open, and the fluorophore is released, generating a measurable signal. The biosensor exhibited high sensitivity and selectivity across diverse matrices, including fish mucus and serum, human serum, sterilized brackish water, and-critically-unprocessed natural lake and seawater samples, without DNA extraction or amplification. Detection limits ranged between 10² and 5 × 10² CFU mL⁻¹, comparable in sensitivity to state-of-the-art qPCR assays. The biosensor outperformed conventional approaches in speed, simplicity, and cost-effectiveness, while maintaining accuracy. These findings underscore the potential of this platform for integrated One Health applications, bridging environmental monitoring with rapid diagnosis of vibriosis in humans and animals. Preliminary results from this study were previously made available as a preprint in SSRN (DOI: https://ssrn.com/abstract=5032822).