iology techniques to analyze its biological information. Fluorescence quantitative PCR technology was used to analyze the expression of exsA after different media stress. [Results] The exsA gene contains an open reading frame (ORF) of 861 bp, encoding 286 amino acids. The physico-chemical analysis shows that the molecular structural formula is C1442H2267N393O441S12, the theoretical molecular weight is 32.549 kD, the theoretical pI value is 6.0, and the protein is non-hydrophilic and unstable. The gene does not contain a transmembrane region, and there is no obvious signal peptide. The prediction result of protein subcellular localization shows that the protein is inside the cell. The deduced amino acid sequence and constructed phylogenetic tree show that V. alginolyticus has a close relationship with Vibrio antiquarius. The qPCR results show that the expression level of exsA in different media is different, highest in TSB medium containing bile salts, followed by DMEM medium, and lowest in ordinary TSB medium. [Conclusions] The gene sequence, molecular structure and isoelectric point of exsA, as well as its expression in three different media were obtained.