Abstract
This study assessed the relative contributions of host genetics and diet in shaping the gut microbiota of rainbow trout. Full sibling fish from four unrelated families, each consisting of individuals derived from the mating of one male and one female belonging to a breeding program, were fed diets containing either vegetable proteins or vegetable oils for two months in comparison to a control diet consisting of only fish protein and fish oil. Two parallel approaches were applied on the same samples: transcriptionally active bacterial populations were examined based on RNA analysis and were compared with bacterial populations obtained from DNA analysis. Comparison of temporal temperature gradient gel electrophoresis (TTGE) profiles from DNA and RNA showed important differences, indicating that active bacterial populations were better described by RNA analysis. Results showed that some bacterial groups were significantly (P<0.05) associated with specific families, indicating that microbiota composition may be influenced by the host. In addition, the effect of diet on microbiota composition was dependent on the trout family.
Highlights
The importance of intestinal bacteria in the nutrition and well being of the host has been established for several animals and was recently demonstrated in fish
Each group of fish was fed one of the following diets: diet D1, where 100% of the protein was provided by fish meal and 100% of the oil was provided by fish oil; diet diet 2 (D2), where 50% of the protein was provided by fish meal and 50% was provided by vegetable meal; and diet diet 3 (D3), where 50% of the oil was provided by fish oil and 50% was provided by rapeseed oil (Table 1)
Diet D1 was the control diet, and diets D2 and D3 contained either vegetable protein or vegetable oil, respectively
Summary
The importance of intestinal bacteria in the nutrition and well being of the host has been established for several animals and was recently demonstrated in fish. Navarrete et al [5] used a combined approach based on 16 S rRNA gene- and rpoB-TTGE analysis to reveal that Lactococcus, Citrobacter, Kluyvera, Obesumbacterium and Shewanella dominated the intestinal microbiota While these studies shed light on the composition of the gut microbiota, the available information does not fully clarify the factors involved in determining this composition. The possible involvement of host genotype, as it relates to immuno-phenotype, has been frequently postulated as a major influence on microbiota composition and stability, though this has been difficult to prove In humans, it is currently unclear how the host’s genetic background influences the gut microbiota because the assessment of the role of genetics in the determination of the microbiota is obscured due to environmental factors, primarily diet. The evaluation of the effect of the host on the gut microbiota can be accomplished in fish by studying different non related families of rainbow trout that are fed controlled diets
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