Gut microbial and metabolic characterization of Atlantic salmon (Salmon salar) challenged with Aeromonas salmonicida

Abstract

The bacterium Aeromonas salmonicida (A. salmonicida) is a pathogen that causes high mortality of Atlantic salmon (Salmon salar), which results in great economic losses to the aquaculture industry in various countries. In this study, Atlantic salmon were exposed to low (LI) and high concentration A. salmonicida bacterial suspension by intraperitoneal injection for 48 h. The results of 16S rRNA sequencing and untargeted metabolomics showed that A. salmonicida exposure changed the structure and metabolomics of the gut microbiota in Atlantic salmon. Compared with the control group, the relative abundance of Romboutsia, Blautia, Agathobacter, Parasutterella, Fusicatenibacter, Butyricicoccus, Dongia, Clostridium sensu stricto 1, and Bacteroides significantly increased in infection groups, and these changes were closely related to some differential metabolites identified by metabolome analysis. In infection groups, we found that taurocholic acid, taurochenodeoxycholic acid, 7-ketolithocholic acid were significantly up-regulation, and significant down-regulation of Vitamin C, vitamin A, indirubin, and hexanoic acid. These differential metabolites are mainly involved in bile secretion, biosynthesis of antibiotics, inflammatory mediator regulation of transient receptor potential channels, tryptophan metabolism, vitamin digestion and absorption, and the ornithine cycle. Our analysis of the connection between the gut microbiota and metabolism confirmed that the gut microbiota may affect Atlantic salmon resist infection by A. salmonicida by regulating metabolism.