Poster Presentation Australian Microbial Ecology 2017

Atlantic Salmon Gut Microbiome Growth Dynamics (#107)

John P Bowman 1 , Barbara Nowak 2 , Victoria Percival 3 , Steve Percival 3
  1. Tasmania Institute Of Agricultural Research, Hobart, TAS, Australia
  2. Insitute of Marine and Antarctic Science, University of Tasmania, Launceston, Tasmania, Australia
  3. Huon Aquaculture Pty., Ltd., Hobart, Tasmania, Australia

Fifteen diet formulations that included  supplementation of different monoturpene essential oils at different doses, provided in encapsulated and non-encapsulated forms, in the presence or absence of probiotic supplements were fed for 6-12 weeks to Atlantic salmon (Salmo salar L.) to determine if these diets could systematically alter hind gut microbiome structure. The feeding trials were conducted during summer to early autumn in replicated cage designs. The effect of diets on salmon growth performance was analysed along with analysis of GI tract morphological characteristics. The bacterial community present in hindgut faecal samples was determined by analysis of 16S rRNA gene amplicons via automated ribosomal integral spacer analysis and with the Illumina MiSeq  sequencing platform. The results indicated that individual diets could affect growth performance, feeding rates and GI tract morphometric characteristics in younger fish (<1.6 kg), however these affects were not discernable as fish grew past 2.5 kg. The hindgut microbiome was found to be overall unaffected statistically by any diet including diets that had an initially observable affect in initial trials of 6 weeks and repeated with larger fish in feeding trials that lasted for 12 weeks. It was observed that digesta microbial growth dynamics over short term scales obscured more subtle effects on the gut microbiome that might be caused by the diets, and that core taxa predominated regardless of supplementation type. A separate experiment determined that freshwater bathing used for anti-amoebic gill disease treatment also had no discernable effect on the community structure confirming previous findings that changes in salinity does not impact hindgut microbiomes in fish, including salmon. The overall results suggests that though the Atlantic salmon hindgut community structure is highly dynamic, the core components and general structure are stable, and that growth during the hind gut resident time represesents the primary source of dynamic change and specimen-to-specimen variability.