The Gut Microbiome of the Wild Baltic Salmon (Salmo salar L.) Parr: Metagenomic Analysis

The gut content microbiome of the wild Baltic salmon (a sub-population of the Atlantic salmon Salmo salar) parr, was first analyzed/using microbial profiling and high taxonomic richness was revealed. At the phylum level, the gut microbiota was dominated by Firmicutes, Actinobacteria, Proteobacteria, Firmicutes being the most abundant. In addition, the relative abundance of Cyanobacteria in the microbiota of the Baltic salmon parr was found to be higher than that in the microbiota of the North - and East- Atlantic salmon, where it was lower or even absent. The phylum Tenericutes (mainly assigned to Mycoplasmataceae), which is common both in the wild North - and East - Atlantic salmon, was not detected in the Baltic salmon. Across all samples, unique amplicon sequence variants (ASVs) belonging to unclassified Bacilli, Actinomycetales, and Rhizobiales were identified as the major taxa. At the genus level, Mycobacterium, Clostridium sensu stricto, and Hyphomicrobium were recorded in all samples but at low levels. Our study has revealed that the microbial communities present in the wild Baltic salmon parr gut differ from those in the wild North - and East- Atlantic salmon.