Environmental monitoring of a climate change indicator (Vibrio vulnificus) in coastal wetland water samples based on field-deployable detection

Global warming is driving rapid changes across all ecological scales, including shifts in the distribution patterns and virulence potential of some pathogenic bacteria. A relevant pathogen affected by climate change is Vibrio vulnificus, a species considered a valuable biomarker because rising temperatures and changes in salinity strongly influence its prevalence and distribution. Comprehensive surveillance at local scales is required to provide precise environmental understanding. However, current monitoring methods are often inaccessible or cost-prohibitive, highlighting the need for fast, field-deployable alternatives. This study hypothesized that combining lateral flow assay with isothermal DNA amplification can enable rapid, on-site detection with minimal instrumentation. To validate the approach, V. vulnificus was monitored in a Mediterranean coastal wetland, a sensitive ecosystem where changes impact biodiversity and may lead to waterborne diseases. The campaign was based on water sampling, an enrichment step, and a DNA-based assay integrated into a microfluidic chip. Species-specific vvhA gene was amplified through recombinase polymerase amplification (RPA), detected on a lateral flow strip, and quantified by a smartphone. The monitoring campaign identified locations within the wetland exhibiting a significant increase in bacterial concentrations, up to 300 times, depending on the sampling site. The bacterium was detected in brackish water areas and inflow/outflow points, showing excellent performance. These promising results suggest that the new procedure can help detect microenvironments that favor or inhibit bacterial growth. The surveillance strategy could be effectively applied on a global scale to assess risks, examine variations associated with climate change, and implement measures against Vibrio infections.