Characterization of biochemical properties of the skin mucus of turbot (Scophthalmus maximu) and differential proteomic analysis of skin mucus in response to Vibrio anguillarum

Abstract

Fish mucus is the first defensive barrier to fight off pathogens in teleosts. In this study, we reported the antibacterial activity of turbot (Scophthalmus maximus) skin mucus, and the results showed that mucus exhibited antibacterial effects against both Gram-positive and Gram-negative bacteria. Moreover, biochemical parameters assays suggested that turbot skin mucus exhibited strong total antioxidant capacity (TAC), protease activity and lysozyme activity. To explore the roles of skin mucus in defense against pathogens, we processed proteomic profiling of turbot skin mucus before and after Vibrio anguillarum infection by LC-MS/MS approach. Differentially expressed proteins (DEPs) were identified among V. anguillarum treated turbot skin mucus at 0 h, 4 h and 48 h post-infection, respectively. A total of 3,324,612 secondary spectrograms were obtained, containing 38,681 unique peptides which were corresponded to 4987 proteins. The DEPs were markedly enriched in Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways associated with immunity, biological adhesion and cell junction, revealing complex changes of turbot skin mucus during pathogens infection. Collectively, this study can help us better understand the characteristics of turbot skin mucus in infection immunity and the biological function of skin mucus in response to bacterial invasion.