Genome-wide analysis of quorum sensing regulon in marine fish pathogen Vibrio scophthalmi

Opportunistic fish pathogen Vibrio scophthalmi frequently infects olive flounder and turbot, which are primary marine species cultured for seafood production in Far East Asia. These infections cause substantial yield reductions and significant economic losses. Although quorum sensing (QS) genes were previously reported in V. scophthalmi, the impacts of QS on genome-wide gene expression and consequent behaviors and physiological traits have remained largely unexplored. In this study, we conducted genomic and transcriptomic analyses to uncover the global regulatory network governed by LuxR_Vs, a QS master regulator in V. scophthalmi. By comparing the wild-type strain and a luxR_Vs deletion mutant strain, we found that LuxR_Vs positively regulates biosynthetic genes for poly-hydroxyalkanoate (PHA) while negatively controlling genes for biofilm formation. Quantification of intracellular PHAs and biofilm biomass on borosilicate tubes confirmed these results. Gene set enrichment analyses further demonstrated that LuxR_Vs also governs genes related to osmoprotection and defense against reactive oxygen species. Overall, these findings indicate that LuxR_Vs acts as a global transcriptional regulator, controlling a wide range of physiological processes in V. scophthalmi. Targeting LuxR_Vs could therefore be a promising strategy for improving seafood production by disrupting diverse physiological and pathogenic traits in this fish pathogen.