During smoltification process, Atlantic salmon (Salmo salar ) displayed molecular and physiological changes allowing the parr-smolt transformation. In farmed fish this process can be modulated through controlled temperature and photoperiod conditions . Although fish changes during smoltification process have been studied in different levels , there are few investigations concerning the role of the fish microbiota . Herein, changes in the metabolic requirements, feeding behavior , and osmoregulation suggest a strong microbiota modulation . Th is study aimed to explore how the intestinal microbiota of Atlantic Salmon can be modulated during the parr-smolt transformation.
The experimental design evaluated a group of Atlantic salmon smolts exposed to gradual salinity change (GSC) and other exposed to salinity shock (SS). Intestinal samples were collected in freshwater (FW) , 10, 32 PSU for GSC group and at 32 PSU for SS. DNA extraction was performed using the phenol: chloroform isoamyl alcohol protocol. Follow, the entire 16S rRNA gene were sequencing in the Nanopore MinION platform. Then reads analysis and BLASTN aligned were performed with EPI2ME software package. The results show that FW intestines have a greater presence of the Alteromonadaceae and Moraxellaceae families. Also, during GSC were observed high abundance of Moraxellaceae family. On the other hand, in salmon exposed to SS, the Vibrionaceae family shows evident predominance. To date, the composition of a healthy microbiota in fish has not been established. However, it has been suggested that high bacterial diversity is an indication of animal welfare . These results indicate that a greater diversity of families is observed in GSC fish compared to those subjected to SS .
Funding: ANID-Chile through the Postdoctoral grant FONDECYT (3190320), and FONDAP (#15110027).